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Pierson SR, Kolling LJ, James TD, Pushpavathi SG, Marcinkiewcz CA. Serotonergic dysfunction may mediate the relationship between alcohol consumption and Alzheimer's disease. Pharmacol Res 2024; 203:107171. [PMID: 38599469 DOI: 10.1016/j.phrs.2024.107171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024]
Abstract
The impact of Alzheimer's disease (AD) and its related dementias is rapidly expanding, and its mitigation remains an urgent social and technical challenge. To date there are no effective treatments or interventions for AD, but recent studies suggest that alcohol consumption is correlated with the risk of developing dementia. In this review, we synthesize data from preclinical, clinical, and epidemiological models to evaluate the combined role of alcohol consumption and serotonergic dysfunction in AD, underscoring the need for further research on this topic. We first discuss the limitations inherent to current data-collection methods, and how neuropsychiatric symptoms common among AD, alcohol use disorder, and serotonergic dysfunction may mask their co-occurrence. We additionally describe how excess alcohol consumption may accelerate the development of AD via direct effects on serotonergic function, and we explore the roles of neuroinflammation and proteostasis in mediating the relationship between serotonin, alcohol consumption, and AD. Lastly, we argue for a shift in current research to disentangle the pathogenic effects of alcohol on early-affected brainstem structures in AD.
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Affiliation(s)
- Samantha R Pierson
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | - Louis J Kolling
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | - Thomas D James
- Department of Neuroscience and Pharmacology, University of Iowa, United States
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2
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Ramkumar R, Edge-Partington M, Terstege DJ, Adigun K, Ren Y, Khan NS, Rouhi N, Jamani NF, Tsutsui M, Epp JR, Sargin D. Long-Term Impact of Early Life Stress on Serotonin Connectivity. Biol Psychiatry 2024:S0006-3223(24)00073-8. [PMID: 38316332 DOI: 10.1016/j.biopsych.2024.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 01/04/2024] [Accepted: 01/19/2024] [Indexed: 02/07/2024]
Abstract
BACKGROUND Chronic childhood stress is a prominent risk factor for developing affective disorders, yet mechanisms underlying this association remain unclear. Maintenance of optimal serotonin (5-HT) levels during early postnatal development is critical for the maturation of brain circuits. Understanding the long-lasting effects of early life stress (ELS) on serotonin-modulated brain connectivity is crucial to develop treatments for affective disorders arising from childhood stress. METHODS Using a mouse model of chronic developmental stress, we determined the long-lasting consequences of ELS on 5-HT circuits and behavior in females and males. Using FosTRAP mice, we cross-correlated regional c-Fos density to determine brain-wide functional connectivity of the raphe nucleus. We next performed in vivo fiber photometry to establish ELS-induced deficits in 5-HT dynamics and optogenetics to stimulate 5-HT release to improve behavior. RESULTS Adult female and male mice exposed to ELS showed heightened anxiety-like behavior. ELS further enhanced susceptibility to acute stress by disrupting the brain-wide functional connectivity of the raphe nucleus and the activity of 5-HT neuron population, in conjunction with increased orbitofrontal cortex (OFC) activity and disrupted 5-HT release in medial OFC. Optogenetic stimulation of 5-HT terminals in the medial OFC elicited an anxiolytic effect in ELS mice in a sex-dependent manner. CONCLUSIONS These findings suggest a significant disruption in 5-HT-modulated brain connectivity in response to ELS, with implications for sex-dependent vulnerability. The anxiolytic effect of the raphe-medial OFC circuit stimulation has potential implications for developing targeted stimulation-based treatments for affective disorders that arise from early life adversities.
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Affiliation(s)
- Raksha Ramkumar
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Moriah Edge-Partington
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Dylan J Terstege
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Kabirat Adigun
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Yi Ren
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nazmus S Khan
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Nahid Rouhi
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Naila F Jamani
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Mio Tsutsui
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jonathan R Epp
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Derya Sargin
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
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Aklan I, Sayar-Atasoy N, Deng F, Kim H, Yavuz Y, Rysted J, Laule C, Davis D, Li Y, Atasoy D. Dorsal raphe serotonergic neurons suppress feeding through redundant forebrain circuits. Mol Metab 2023; 69:101676. [PMID: 36682413 PMCID: PMC9923194 DOI: 10.1016/j.molmet.2023.101676] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/04/2022] [Accepted: 01/13/2023] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE Serotonin (5HT) is a well-known anorexigenic molecule, and 5HT neurons of dorsal raphe nucleus (DRN) have been implicated in suppression of feeding; however, the downstream circuitry is poorly understood. Here we explored major projections of DRN5HT neurons for their capacity to modulate feeding. METHODS We used optogenetics to selectively activate DRN5HT axonal projections in hypothalamic and extrahypothalamic areas and monitored food intake. We next used fiber photometry to image the activity dynamics of DRN5HT axons and 5HT levels in projection areas in response feeding and metabolic hormones. Finally, we used electrophysiology to determine how DRN5HT axons affect downstream neuron activity. RESULTS We found that selective activation of DRN5HT axons in (DRN5HT → LH) and (DRN5HT → BNST) suppresses feeding whereas activating medial hypothalamic projections has no effect. Using in vivo imaging, we found that food access and satiety hormones activate DRN5HT projections to LH where they also rapidly increase extracellular 5HT levels. Optogenetic mapping revealed that DRN5HT → LHvGAT and DRN5HT → LHvGlut2 connections are primarily inhibitory and excitatory respectively. Further, in addition to its direct action on LH neurons, we found that 5HT suppresses GABA release from presynaptic terminals arriving from AgRP neurons. CONCLUSIONS These findings define functionally redundant forebrain circuits through which DRN5HT neurons suppress feeding and reveal that these projections can be modulated by metabolic hormones.
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Affiliation(s)
- Iltan Aklan
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Nilufer Sayar-Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Fei Deng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Hyojin Kim
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yavuz Yavuz
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA,Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Jacob Rysted
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Connor Laule
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Debbie Davis
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Deniz Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA; Fraternal Order of Eagles Diabetes Research Center (FOEDRC), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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Khan KM, Bierlein-De La Rosa G, Biggerstaff N, Pushpavathi Selvakumar G, Wang R, Mason S, Dailey ME, Marcinkiewcz CA. Adolescent ethanol drinking promotes hyperalgesia, neuroinflammation and serotonergic deficits in mice that persist into adulthood. Brain Behav Immun 2023; 107:419-431. [PMID: 35907582 PMCID: PMC10289137 DOI: 10.1016/j.bbi.2022.07.160] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 07/19/2022] [Accepted: 07/23/2022] [Indexed: 02/09/2023] Open
Abstract
Adolescent alcohol use can permanently alter brain function and lead to poor health outcomes in adulthood. Emerging evidence suggests that alcohol use can predispose individuals to pain disorders or exacerbate existing pain conditions, but the underlying neural mechanisms are currently unknown. Here we report that mice exposed to adolescent intermittent access to ethanol (AIE) exhibit increased pain sensitivity and depressive-like behaviors that persist for several weeks after alcohol cessation and are accompanied by elevated CD68 expression in microglia and reduced numbers of serotonin (5-HT)-expressing neurons in the dorsal raphe nucleus (DRN). 5-HT expression was also reduced in the thalamus, anterior cingulate cortex (ACC) and amygdala as well as the lumbar dorsal horn of the spinal cord. We further demonstrate that chronic minocycline administration after AIE alleviated hyperalgesia and social deficits, while chemogenetic activation of microglia in the DRN of ethanol-naïve mice reproduced the effects of AIE on pain and social behavior. Chemogenetic activation of microglia also reduced tryptophan hydroxylase 2 (Tph2) expression and was negatively correlated with the number of 5-HT-immunoreactive cells in the DRN. Taken together, these results indicate that microglial activation in the DRN may be a primary driver of pain, negative affect, and 5-HT depletion after AIE.
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Affiliation(s)
- Kanza M Khan
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | | | - Natalie Biggerstaff
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | | | - Ruixiang Wang
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | - Suzanne Mason
- Department of Neuroscience and Pharmacology, University of Iowa, United States
| | - Michael E Dailey
- Iowa Neuroscience Institute, University of Iowa, United States; Department of Biology, University of Iowa, United States
| | - Catherine A Marcinkiewcz
- Department of Neuroscience and Pharmacology, University of Iowa, United States; Iowa Neuroscience Institute, University of Iowa, United States.
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Glover ME, Unroe KA, Moughnyeh MM, McCoy C, Kerman IA, Clinton SM. Structural and metabolic activity differences in serotonergic cell groups in a rat model of individual differences of emotionality and stress reactivity. Neurosci Lett 2022; 784:136752. [PMID: 35753615 DOI: 10.1016/j.neulet.2022.136752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 11/27/2022]
Abstract
Serotonin regulates a diverse set of functions, including emotional behavior, cognition, sociability, appetite, and sleep. Serotonin is also a key trophic factor that shapes neurodevelopmental processes. Genetic and environmental factors that drive individual differences in the serotonergic system have the capacity to impact brain structure and behavior, and likely contribute to pathophysiological processes involved in neuropsychiatric disorders. Using adult rats selectively bred for low novelty exploration (Low Responders, LR), we previously demonstrated pronounced increases in the levels of their anxiety- and depression- relevant behaviors as compared to the selectively bred High Novelty Responder (HR) rats. These behavioral differences were accompanied by alterations in the expression of genes that regulate serotonin synthesis in the brainstem, and its signaling in the forebrain. The present study extends these observations with a focus on the organization and the metabolism of brainstem serotonin cell groups that provide serotonergic innervation of the hippocampus and other limbic regions of male HR/LR rats. Using design-based stereology, we found the median raphe (MnR) in adult male LR rats contains increased number of serotonergic neurons as compared to the HRs. This is preceded by an increase in the metabolic activity of the caudal dorsal raphe (DRC) and the intrafascicular DR (DRI) during early postnatal development. These findings suggest that structural and functional differences in the raphe-limbic projections shape behavioral inhibition throughout the lifespan.
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Affiliation(s)
| | - Keaton A Unroe
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA; Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA, USA
| | | | - Chelsea McCoy
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
| | - Ilan A Kerman
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA; Behavioral Health Service Line, Veterans Affairs Pittsburgh Health System, Pittsburgh, PA 15240, USA
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Abstract
Up to 20% of women experience stress-related disorders during the postpartum period; however, little is known about the specific neural circuitry by which maternal stress exerts its negative impacts on mental health and maternal caregiving behavior. Theoretically, such a circuitry should serve as an interface between the stress response system and maternal neural network, transmitting stress signals to the neural circuitry that mediates maternal behavior. In this paper, I propose that the lateral habenula (LHb) serves this interface function. Evidence shows that the LHb plays a key role in encoding stress-induced effects and in the pathophysiology of major depression and stress-related anxiety, and thus may play a role in maternal behavior as part of the maternal brain network. I hypothesize that maternal stress acts upon the LHb and two of its major downstream targets, i.e., ventral tegmental area (VTA) and dorsal raphe nucleus (DRN), compromising the maternal care and contributing to postpartum mental disorders. This hypothesis makes three predictions: (1) maternal stress enhances LHb neuronal activity; (2) activation of DRN- and VTA-projecting neurons in the LHb mimics the detrimental effects of maternal stress on maternal behavior; and (3) suppression of DRN- and VTA-projecting neurons in the LHb attenuates the detrimental effects of maternal stress on maternal care in stressed mothers. Confirmation of this hypothesis is expected to enhance our understanding of the neurocircuit mechanisms mediating stress effects on maternal behavior.
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Affiliation(s)
- Ming Li
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. E-mail:
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7
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Pomrenze MB, Walker LC, Giardino WJ. Gray areas: Neuropeptide circuits linking the Edinger-Westphal and Dorsal Raphe nuclei in addiction. Neuropharmacology 2021; 198:108769. [PMID: 34481834 PMCID: PMC8484048 DOI: 10.1016/j.neuropharm.2021.108769] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 01/16/2023]
Abstract
The circuitry of addiction comprises several neural networks including the midbrain - an expansive region critically involved in the control of motivated behaviors. Midbrain nuclei like the Edinger-Westphal (EW) and dorsal raphe (DR) contain unique populations of neurons that synthesize many understudied neuroactive molecules and are encircled by the periaqueductal gray (PAG). Despite the proximity of these special neuron classes to the ventral midbrain complex and surrounding PAG, functions of the EW and DR remain substantially underinvestigated by comparison. Spanning approximately -3.0 to -5.2 mm posterior from bregma in the mouse, these various cell groups form a continuum of neurons that we refer to collectively as the subaqueductal paramedian zone. Defining how these pathways modulate affective behavioral states presents a difficult, yet conquerable challenge for today's technological advances in neuroscience. In this review, we cover the known contributions of different neuronal subtypes of the subaqueductal paramedian zone. We catalogue these cell types based on their spatial, molecular, connectivity, and functional properties and integrate this information with the existing data on the EW and DR in addiction. We next discuss evidence that links the EW and DR anatomically and functionally, highlighting the potential contributions of an EW-DR circuit to addiction-related behaviors. Overall, we aim to derive an integrated framework that emphasizes the contributions of EW and DR nuclei to addictive states and describes how these cell groups function in individuals suffering from substance use disorders. This article is part of the special Issue on 'Neurocircuitry Modulating Drug and Alcohol Abuse'.
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Affiliation(s)
- Matthew B Pomrenze
- Dept. of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305-5453, USA
| | - Leigh C Walker
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3052, Australia
| | - William J Giardino
- Dept. of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305-5453, USA; Wu Tsai Neurosciences Institute, Stanford University School of Medicine, Stanford, CA, 94305-5453, USA.
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Grieb ZA, Ford EG, Yagan M, Lau BYB, Manfredsson FP, Krishnan K, Lonstein JS. Oxytocin receptors in the midbrain dorsal raphe are essential for postpartum maternal social and affective behaviors. Psychoneuroendocrinology 2021; 131:105332. [PMID: 34182251 PMCID: PMC8405581 DOI: 10.1016/j.psyneuen.2021.105332] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/07/2021] [Accepted: 06/15/2021] [Indexed: 01/23/2023]
Abstract
Oxytocin receptors (OTRs) in the midbrain dorsal raphe (DR; the source of most forebrain serotonin) have recently been identified as a potential pharmacological target for treating numerous psychiatric disorders. However, almost all research on this topic has been conducted on males and the role of DR OTRs in female social and affective behaviors is mostly unknown. This may be particularly relevant during early motherhood, which is a time of high endogenous oxytocin signaling, but also a time of elevated risk for psychiatric dysfunction. To investigate whether OTRs in the DR are necessary for postpartum female social and affective behaviors, we constructed and then injected into the DR an adeno-associated virus permanently expressing an shRNA targeting OTR mRNA. We then observed a suite of social and affective behaviors postpartum. OTR knockdown in the maternal DR led to pup loss after parturition, decreased nursing, increased aggression, and increased behavioral despair. These effects of OTR knockdown in the DR may be due to disrupted neuroplasticity in the primary somatosensory cortex (S1), which mediates maternal sensitivity to the tactile cues from young, as we found significantly more plasticity-restricting perineuronal nets (PNNs) in the S1 rostral barrel field and fewer PNNs in the caudal barrel field of OTR-knockdown mothers. These results demonstrate that OTRs in the midbrain DR are essential for postpartum maternal social and affective behaviors, are involved in postpartum cortical plasticity, and suggest that pharmacotherapies targeting OTRs in the DR could be effective treatments for some peripartum affective disorders.
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Affiliation(s)
- Zachary A Grieb
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA.
| | - Emma G Ford
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA
| | - Mahircan Yagan
- Deparment of Biochemistry & Cellular and Molecular Biology, University of Tennessee, 1311 Cumberland Avenue, Knoxville, TN 37996, USA
| | - Billy Y B Lau
- Deparment of Biochemistry & Cellular and Molecular Biology, University of Tennessee, 1311 Cumberland Avenue, Knoxville, TN 37996, USA
| | - Fredric P Manfredsson
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI 49503, USA
| | - Keerthi Krishnan
- Deparment of Biochemistry & Cellular and Molecular Biology, University of Tennessee, 1311 Cumberland Avenue, Knoxville, TN 37996, USA
| | - Joseph S Lonstein
- Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA
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Harley CW, Walling SG, Yuan Q, Martin GM. The 'a, b, c's of pretangle tau and their relation to aging and the risk of Alzheimer's Disease. Semin Cell Dev Biol 2021; 116:125-34. [PMID: 33674223 DOI: 10.1016/j.semcdb.2020.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/07/2020] [Accepted: 12/21/2020] [Indexed: 12/11/2022]
Abstract
Braak has described the beginnings of Alzheimer's Disease as occurring in the locus coeruleus. Here we review these pretangle stages and relate their expression to recently described normal features of tau biology. We suggest pretangle tau depends on characteristics of locus coeruleus operation that promote tau condensates. We examine the timeline of pretangle and tangle appearance in locus coeruleus. We find catastrophic loss of locus coeruleus neurons is a late event. The strong relationship between locus coeruleus neuron number and human cognition underscores the utility of a focus on locus coeruleus. Promoting locus coeruleus health will benefit normal aging as well as aid in the prevention of dementia. Two animal models offering experimental approaches to understanding the functional change initiated by pretangles in locus coeruleus neurons are discussed.
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10
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Li C, McCloskey N, Phillips J, Simmons SJ, Kirby LG. CRF-5-HT interactions in the dorsal raphe nucleus and motivation for stress-induced opioid reinstatement. Psychopharmacology (Berl) 2021; 238:29-40. [PMID: 33231727 DOI: 10.1007/s00213-020-05652-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/20/2020] [Indexed: 01/17/2023]
Abstract
RATIONALE The serotonin (5-hydroxytryptamine, 5-HT) system plays an important role in stress-related psychiatric disorders and substance abuse. Our previous data show that stressors can inhibit 5-HT neuronal activity and release by stimulating the release of the stress neurohormone corticotropin-releasing factor (CRF) within the serotonergic dorsal raphe nucleus (DRN). The inhibitory effects of CRF on 5-HT DRN neurons are indirect, mediated by CRF-R1 receptors located on GABAergic afferents. OBJECTIVES We tested the hypothesis that DRN CRF-R1 receptors contribute to stress-induced reinstatement of morphine-conditioned place preference (CPP). We also examined the role of this circuitry in stress-induced negative affective state with 22-kHz distress ultrasonic vocalizations (USVs), which are naturally emitted by rats in response to environmental challenges such as pain, stress, and drug withdrawal. METHODS First, we tested if activation of CRF-R1 receptors in the DRN with the CRF-R1-preferring agonist ovine CRF (oCRF) would reinstate morphine CPP and then if blockade of CRF-R1 receptors in the DRN with the CRF-R1 antagonist NBI 35965 would attenuate swim stress-induced reinstatement of morphine CPP. Second, we tested if intra-DRN pretreatment with NBI 35965 would attenuate foot shock stress-induced 22-kHz USVs. RESULTS Intra-DRN injection of oCRF reinstated morphine CPP, while intra-DRN injection of NBI 35965 attenuated swim stress-induced reinstatement. Moreover, intra-DRN pretreatment with NBI 35965 significantly reduced 22-kHz distress calls induced by foot shock. CONCLUSIONS These data provide evidence that stress-induced negative affective state is mediated by DRN CRF-R1 receptors and may contribute to reinstatement of morphine CPP.
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Belliveau S, Kang W, Bovaird S, Hamadjida A, Bédard D, Dancause N, Stroh T, Huot P. Stereological investigation of 5-HT 3 receptors in the substantia nigra and dorsal raphe nucleus in the rat. J Chem Neuroanat 2020; 111:101881. [PMID: 33160048 DOI: 10.1016/j.jchemneu.2020.101881] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Serotonin (5-HT) is a common neurotransmitter in mammals, playing a central role in the regulation of various processes such as sleep, perception, cognitive and autonomic functions in the nervous system. Previous studies have demonstrated that 5-HT type 3 (5-HT3) receptors are expressed in either or both the substantia nigra (SN) and the dorsal raphe nucleus (DRN) in humans, marmosets, rats and Syrian hamsters. Here, we quantify the distribution of 5-HT3 receptors across these regions in the adult rat. Fluorescent immunohistochemistry was performed on sections of rat brain covering the entire rostro-caudal extent of the SN and DRN with antibodies specific to the 5-HT3A receptor subunit, as well as others targeting the monoaminergic markers tyrosine hydroxylase (TH) and the 5-HT transporter (SERT). The number of 5-HT3A receptor-positive, TH-positive (n = 28,428 ± 888, Gundersen's m = 1 coefficient of error [CE] = 0.05) and SERT-positive (n = 12,852 ± 462, CE = 0.06) cells were estimated in both the SN and the DRN using stereology. We found that 5-HT3A receptor-positive cells are present in the SNr (n = 1250 ± 64, CE = 0.24), but they did not co-localise with TH-positive cells, nor were they present in the SNc. In contrast, no 5-HT3A receptor-positive cells were found in the DRN. These results support the presence of 5-HT3 receptors in the SN, but not in the DRN, and do not support their expression on monoaminergic cells within these two brain areas.
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Affiliation(s)
| | - Woojin Kang
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada
| | - Samantha Bovaird
- Department of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Adjia Hamadjida
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada
| | - Dominique Bédard
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada
| | - Numa Dancause
- Département de Neurosciences, Université de Montréal, Montreal, QC, Canada
| | - Thomas Stroh
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada
| | - Philippe Huot
- Montreal Neurological Institute and Hospital, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; Department of Neurosciences, McGill University Health Centre, Montreal, QC, Canada.
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12
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Bagge EK, Fujimori-Tonou N, Kubota-Sakashita M, Kasahara T, Kato T. Unbiased PCR-free spatio-temporal mapping of the mtDNA mutation spectrum reveals brain region-specific responses to replication instability. BMC Biol 2020; 18:150. [PMID: 33097039 PMCID: PMC7585204 DOI: 10.1186/s12915-020-00890-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 10/06/2020] [Indexed: 12/24/2022] Open
Abstract
Background The accumulation of mtDNA mutations in different tissues from various mouse models has been widely studied especially in the context of mtDNA mutation-driven ageing but has been confounded by the inherent limitations of the most widely used approaches. By implementing a method to sequence mtDNA without PCR amplification prior to library preparation, we map the full unbiased mtDNA mutation spectrum across six distinct brain regions from mice. Results We demonstrate that ageing-induced levels of mtDNA mutations (single nucleotide variants and deletions) reach stable levels at 50 weeks of age but can be further elevated specifically in the cortex, nucleus accumbens (NAc), and paraventricular thalamic nucleus (PVT) by expression of a proof-reading-deficient mitochondrial DNA polymerase, PolgD181A. The increase in single nucleotide variants increases the fraction of shared SNVs as well as their frequency, while characteristics of deletions remain largely unaffected. In addition, PolgD181A also induces an ageing-dependent accumulation of non-coding control-region multimers in NAc and PVT, a feature that appears almost non-existent in wild-type mice. Conclusions Our data provide a novel view of the spatio-temporal accumulation of mtDNA mutations using very limited tissue input. The differential response of brain regions to a state of replication instability provides insight into a possible heterogenic mitochondrial landscape across the brain that may be involved in the ageing phenotype and mitochondria-associated disorders.
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Affiliation(s)
- Emilie Kristine Bagge
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Noriko Fujimori-Tonou
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Saitama, Japan.,Current address: Support Unit for Bio-Material Analysis, Research Resources Division, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Mie Kubota-Sakashita
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Takaoki Kasahara
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Saitama, Japan.,Current address: Career Development Program, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Tadafumi Kato
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Saitama, Japan. .,Department of Psychiatry and Behavioral Science, Juntendo University, Graduate School of Medicine, Hongo 2-1-1, Bunkyo, Tokyo 113-8421, Japan.
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13
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Abstract
A recent cluster of reports have considerably deepened our understanding of the transcriptional diversity of serotonin neurons of the dorsal raphe nucleus (DR). In this commentary a subset of implications from these studies is highlighted such as: serotonin neurons in the lateral wings have a newly discovered close relationship with those in rostral and dorsal locations and that cre-lines may be just as likely to cut across several transcriptional subtypes as to define a single subtype. To evolve understanding of DR organization, it may be prudent to correlate transcriptional snapshots in time with other known features of DR neurons. Here we bring together new and old information on serotonin neuron diversity with the goal of developing increasingly useful schemes of DR organization.
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14
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Rigney N, Beaumont R, Petrulis A. Sex differences in vasopressin 1a receptor regulation of social communication within the lateral habenula and dorsal raphe of mice. Horm Behav 2020; 121:104715. [PMID: 32067962 PMCID: PMC7249673 DOI: 10.1016/j.yhbeh.2020.104715] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/04/2020] [Accepted: 02/09/2020] [Indexed: 02/06/2023]
Abstract
The neuropeptide arginine-vasopressin (AVP) has long been implicated in the regulation of social behavior and communication in diverse taxa, often through its actions on the V1a receptor (V1aR) and in a sex-different and steroid-dependent way. One source of sex-different brain AVP is the steroid-sensitive and sexually-dimorphic AVP neurons in the bed nucleus of the stria terminalis (BNST), a cell population that regulates social behavior in a sex-dependent manner. Potential targets of these BNST-AVP cells include the lateral habenula (LHb) and dorsal raphe (DR), areas known to be important for social behavior, yet few studies have investigated AVP action within these regions. Consequently, to test if V1aR action in the LHb or DR controls social behavior in a sexually dimorphic manner, we administered a highly-specific V1aR antagonist (or saline vehicle) in the LHb or DR of C57BL/6 male and female mice and tested its effects on social investigation, social communication (urine marking, ultrasonic vocalizations), and territorial aggression. V1aR antagonism of the LHb or DR decreased male urine marking toward unfamiliar males, but not toward unfamiliar females. Additionally, V1aR blockade of the LHb decreased ultrasonic vocalizations generated in the presence of females. Social investigation, locomotion and aggressive behavior were not altered by V1aR antagonism in either area. Blocking V1aR in the LHb or DR of females had no effect, indicating V1aR action in the DR and LHb drives sex differences in social communication.
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Affiliation(s)
- Nicole Rigney
- Neuroscience Institute, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA; Center for Behavioral Neuroscience, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA.
| | - Rachael Beaumont
- Neuroscience Institute, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA; Center for Behavioral Neuroscience, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA.
| | - Aras Petrulis
- Neuroscience Institute, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA; Center for Behavioral Neuroscience, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA 30303, USA.
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15
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Adidharma W, Deats SP, Ikeno T, Lipton JW, Lonstein JS, Yan L. Orexinergic modulation of serotonin neurons in the dorsal raphe of a diurnal rodent, Arvicanthis niloticus. Horm Behav 2019; 116:104584. [PMID: 31445011 PMCID: PMC6885537 DOI: 10.1016/j.yhbeh.2019.104584] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/02/2019] [Accepted: 08/20/2019] [Indexed: 01/22/2023]
Abstract
The hypothalamic neuropeptide, orexin (or hypocretin), is implicated in numerous physiology and behavioral functions, including affective states such as depression and anxiety. The underlying mechanisms and neural circuits through which orexin modulates affective responses remain unclear. The objective of the present study was to test the hypothesis that the serotonin (5-HT) system of the dorsal raphe nucleus (DRN) is a downstream target through which orexin potentially manifests its role in affective states. Using a diurnal rodent, the Nile grass rat (Arvicanthis niloticus), we first characterized the expression of the orexin receptors OX1R and OX2R in the DRN using in situ hybridization. The results revealed distinct distributions of OX1R and OX2R mRNAs, with OX1R predominantly expressed in the dorsal and lateral wings of the DRN that are involved in affective processes, while OX2R was mostly found in the ventral DRN that is more involved in sensory-motor function. We next examined how the orexin-OX1R pathway regulates 5-HT in the DRN and some of its projection sites using a selective OX1R antagonist SB-334867 (10 mg/kg, i.p.). A single injection of SB-334867 decreased 5-HT-ir fibers within the anterior cingulate cortex (aCgC); five once-daily administrations of SB-334867 decreased 5-HT-ir not only in the aCgC but also in the DRN, oval bed nucleus of the stria terminalis (ovBNST), nucleus accumbens shell (NAcSh), and periaqueductal gray (PAG). HPLC analysis revealed that five once-daily administrations of SB-334867 did not affect 5-HT turnover to any of the five sites, although it increased the levels of both 5-HT and 5-HIAA in the NAcSh. These results together suggest that orexinergic modulation of DRN 5-HT neurons via OX1Rs may be one pathway through which orexin regulates mood and anxiety, as well as perhaps other neurobiological processes.
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Affiliation(s)
- Widya Adidharma
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA
| | - Sean P Deats
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA
| | - Tomoko Ikeno
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - Jack W Lipton
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA; Department of Translational Science & Molecular Medicine, Michigan State University, Grand Rapids, MI, 49503, USA
| | - Joseph S Lonstein
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - Lily Yan
- Department of Psychology, Michigan State University, East Lansing, MI 48824, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
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16
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Ross AP, McCann KE, Larkin TE, Song Z, Grieb ZA, Huhman KL, Albers HE. Sex-dependent effects of social isolation on the regulation of arginine-vasopressin (AVP) V1a, oxytocin (OT) and serotonin (5HT) 1a receptor binding and aggression. Horm Behav 2019; 116:104578. [PMID: 31449813 PMCID: PMC6885541 DOI: 10.1016/j.yhbeh.2019.104578] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/29/2019] [Accepted: 08/20/2019] [Indexed: 11/20/2022]
Abstract
It is widely held that social isolation produces higher rates of mortality and morbidity and has deleterious effects on an individual's sociality. Relatedly, it is widely observed that socially isolated adult rodents display significantly higher levels of aggression when placed in a social situation than do their conspecifics living in social groups. In the following study, we investigated the effects of social isolation on several neurochemical signals that play key roles in the regulation of social behavior in adults. More specifically, we examined the effects of social isolation on vasopressin (AVP) V1a, oxytocin (OT) and serotonin (5-HT)1a receptor binding within the neural circuit controlling social behavior. Male and female Syrian hamsters were housed individually or with two other hamsters for four weeks and were then tested with a same-sex nonaggressive intruder in a neutral arena for 5 min. Social isolation significantly increased aggression in both males and females and altered receptor binding in several brain regions in a sex-dependent manner. For example, V1a receptor binding was greater in socially isolated males in the anterior hypothalamus than it was in any other group. Taken together, these data provide substantial new support for the proposition that the social environment can have a significant impact on the structural and neurochemical mechanisms regulating social behavior and that the amount and type of social interactions can produce differential effects on the circuit regulating social behavior in a sex-dependent manner.
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Affiliation(s)
- Amy P Ross
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - Katharine E McCann
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - Tony E Larkin
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - Zhimin Song
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - Zachary A Grieb
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - Kim L Huhman
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America
| | - H Elliott Albers
- Neuroscience Institute, Georgia State University, United States of America; Center for Behavioral Neuroscience, Atlanta, GA, United States of America.
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17
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Finnell JE, Moffitt CM, Hesser LA, Harrington E, Melson MN, Wood CS, Wood SK. The contribution of the locus coeruleus-norepinephrine system in the emergence of defeat-induced inflammatory priming. Brain Behav Immun 2019; 79:102-113. [PMID: 30707932 PMCID: PMC6591045 DOI: 10.1016/j.bbi.2019.01.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 12/21/2018] [Accepted: 01/21/2019] [Indexed: 12/14/2022] Open
Abstract
Exposure to psychosocial stress is known to precipitate the emergence of stress related psychiatric disorders such as depression and anxiety. While mechanisms by which this occurs remain largely unclear, recent evidence points towards a causative role for inflammation. Neurotransmitters, such as norepinephrine (NE), are capable of regulating expression of proinflammatory cytokines and thus may contribute to the emergence of stress-related disorders. The locus coeruleus (LC) is the major source of norepinephrine (NE) to the brain and therefore the current study utilized N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), an LC selective noradrenergic neurotoxin, to determine the discrete involvement of the LC-NE system in social defeat-induced inflammation in LC projection regions including the central amygdala (CeA), dorsal raphe (DR) and plasma. In the current study, rats were exposed to brief social defeat or control manipulations on 5 consecutive days. To determine whether a history of social defeat enhanced or "primed" the inflammatory response to a subsequent defeat exposure, all rats regardless of stress history were exposed to an acute social defeat challenge immediately preceeding tissue collection. As anticipated, prior history of social defeat primed inflammatory responses in the plasma and CeA while neuroinflammation in the DR was markedly reduced. Notably, DSP-4 treatment suppressed stress-induced circulating inflammatory cytokines independent of prior stress history. In contrast, neuroinflammation in the CeA and DR were greatly augmented selectively in DSP-4 treated rats with a history of social defeat. Together these data highlight the dichotomous nature of NE in stress-induced inflammatory priming in the periphery and the brain and directly implicate the LC-NE system in these processes.
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Affiliation(s)
- Julie E Finnell
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Casey M Moffitt
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - L Ande Hesser
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Evelynn Harrington
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Michael N Melson
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Christopher S Wood
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Susan K Wood
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States.
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18
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Park SS, Park HS, Kim CJ, Baek SS, Kim TW. Exercise attenuates maternal separation-induced mood disorder-like behaviors by enhancing mitochondrial functions and neuroplasticity in the dorsal raphe. Behav Brain Res 2019; 372:112049. [PMID: 31229645 DOI: 10.1016/j.bbr.2019.112049] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 06/05/2019] [Accepted: 06/20/2019] [Indexed: 01/28/2023]
Abstract
Loss of the mother-infant relationship during early childhood affects infant development and is known to increase the infant's vulnerability to neuropsychiatric disorders throughout life. Serotonin deficits and mitochondrial dysfunction in the dorsal raphe may underlie mood disorders such as anxiety and depression. Exercise is known to have a positive effect on brain function. In this study, we investigated the effect of exercise on mitochondrial function, apoptosis, and serotonin levels in the dorsal raphe as well as behavioral changes in cases of maternal separation. Exposure to the stress of maternal separation resulted in mitochondrial dysfunction in the dorsal raphe, including impaired Ca2+ homeostasis, an increase in reactive oxygen species such as H2O2, and a decrease in the O2 respiration rate. Exposure to maternal separation stress also decreased tryptophan hydroxylase and 5-hydroxytryptamine positive cells and increased apoptosis, anxiety, and depression. The impairments in mitochondrial function, apoptosis, and serotonin in the dorsal raphe, as well as anxiety and depression, were all improved by exercise. Exercise might alter mitochondrial function, serotonin levels, and the rate of apoptosis in the dorsal raphe. Therefore, exercise might be an important non-pharmacological intervention for the prevention and treatment of the adverse effects of maternal separation.
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Affiliation(s)
- Sang-Seo Park
- Department of physiology, college of medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Hey-Sang Park
- Department of Kinesiology, College of public health and Cardiovascular Research Center, Lewis Katz school of Medicine, Temple University, Philadelphia, PA, USA
| | - Chang-Ju Kim
- Department of physiology, college of medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Seung-Soo Baek
- Exercise Rehabilitation Research Institute, Department of Exercise & Health Science, Sangmyung University, Seoul, Republic of Korea
| | - Tae-Woon Kim
- Department of physiology, college of medicine, Kyung Hee University, Seoul, Republic of Korea; Exercise Rehabilitation Research Institute, Department of Exercise & Health Science, Sangmyung University, Seoul, Republic of Korea.
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19
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Abstract
Many pregnant and postpartum women worldwide suffer from high anxiety and/or depression, which can have detrimental effects on maternal and infant well-being. The first-line pharmacotherapies for prepartum and postpartum affective disorders continue to be the selective serotonin reuptake inhibitors (SSRIs), despite the lack of large well-controlled studies demonstrating their efficacy in reproducing women and the potential for fetal/neonatal exposure to the drugs. Prepartum or postpartum use of SSRIs or other drugs that modulate the brain's serotonin system is also troubling because very little is known about the typical, let alone the atypical, changes that occur in the female central serotonin system across reproduction. We do know from a handful of studies of women and female laboratory rodents that numerous aspects of the central serotonin system are naturally dynamic across reproduction and are also affected by pregnancy stress (a major predisposing factor for maternal psychopathology). Thus, it should not be assumed that the maternal central serotonin system being targeted by SSRIs is identical to non-parous females or males. More information about the normative and stress-derailed changes in the maternal central serotonin system is essential for understanding how serotonin is involved in the etiology of, and the best use of SSRIs for potentially treating, affective disorders in the pregnant and postpartum populations.
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Affiliation(s)
- Joseph S. Lonstein
- Department of Psychology & Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA
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20
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Sellnow RC, Newman JH, Chambers N, West AR, Steece-Collier K, Sandoval IM, Benskey MJ, Bishop C, Manfredsson FP. Regulation of dopamine neurotransmission from serotonergic neurons by ectopic expression of the dopamine D2 autoreceptor blocks levodopa-induced dyskinesia. Acta Neuropathol Commun 2019; 7:8. [PMID: 30646956 PMCID: PMC6332643 DOI: 10.1186/s40478-018-0653-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 12/01/2022] Open
Abstract
Levodopa-induced dyskinesias (LID) are a prevalent side effect of chronic treatment with levodopa (L-DOPA) for the motor symptoms of Parkinson’s disease (PD). It has long been hypothesized that serotonergic neurons of the dorsal raphe nucleus (DRN) are capable of L-DOPA uptake and dysregulated release of dopamine (DA), and that this “false neurotransmission” phenomenon is a main contributor to LID development. Indeed, many preclinical studies have demonstrated LID management with serotonin receptor agonist treatment, but unfortunately, promising preclinical data has not been translated in large-scale clinical trials. Importantly, while there is an abundance of convincing clinical and preclinical evidence supporting a role of maladaptive serotonergic neurotransmission in LID expression, there is no direct evidence that dysregulated DA release from serotonergic neurons impacts LID formation. In this study, we ectopically expressed the DA autoreceptor D2Rs (or GFP) in the DRN of 6-hydroxydopamine (6-OHDA) lesioned rats. No negative impact on the therapeutic efficacy of L-DOPA was seen with rAAV-D2Rs therapy. However, D2Rs treated animals, when subjected to a LID-inducing dose regimen of L-DOPA, remained completely resistant to LID, even at high doses. Moreover, the same subjects remained resistant to LID formation when treated with direct DA receptor agonists, suggesting D2Rs activity in the DRN blocked dyskinesogenic L-DOPA priming of striatal neurons. In vivo microdialysis confirmed that DA efflux in the striatum was reduced with rAAV-D2Rs treatment, providing explicit evidence that abnormal DA release from DRN neurons can affect LID. This is the first direct evidence of dopaminergic neurotransmission in DRN neurons and its modulation with rAAV-D2Rs gene therapy confirms the serotonin hypothesis in LID, demonstrating that regulation of serotonergic neurons achieved with a gene therapy approach offers a novel and potent antidyskinetic therapy.
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21
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Cathala A, Devroye C, Drutel G, Revest JM, Artigas F, Spampinato U. Serotonin 2B receptors in the rat dorsal raphe nucleus exert a GABA-mediated tonic inhibitory control on serotonin neurons. Exp Neurol 2018; 311:57-66. [PMID: 30257183 DOI: 10.1016/j.expneurol.2018.09.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/10/2018] [Accepted: 09/22/2018] [Indexed: 11/30/2022]
Abstract
The central serotonin2B receptor (5-HT2BR) is a well-established modulator of dopamine (DA) neuron activity in the rodent brain. Recent studies in rats have shown that the effect of 5-HT2BR antagonists on accumbal and medial prefrontal cortex (mPFC) DA outflow results from a primary action in the dorsal raphe nucleus (DRN), where they activate 5-HT neurons innervating the mPFC. Although the mechanisms underlying this interaction remain largely unknown, data in the literature suggest the involvement of DRN GABAergic interneurons in the control of 5-HT activity. The present study examined this hypothesis using in vivo (intracerebral microdialysis) and in vitro (immunohistochemistry coupled to reverse transcription-polymerase chain reaction) experimental approaches in rats. Intraperitoneal (0.16 mg/kg) or intra-DRN (1 μM) administration of the selective 5-HT2BR antagonist RS 127445 increased 5-HT outflow in both the DRN and the mPFC, these effects being prevented by the intra-DRN perfusion of the GABAA antagonist bicuculline (100 μM), as well as by the subcutaneous (0.16 mg/kg) or the intra-DRN (0.1 μM) administration of the selective 5-HT1AR antagonist WAY 100635. The increase in DRN 5-HT outflow induced by the intra-DRN administration of the selective 5-HT reuptake inhibitor citalopram (0.1 μM) was potentiated by the intra-DRN administration (0.5 μM) of RS 127445 only in the absence of bicuculline perfusion. Finally, in vitro experiments revealed the presence of the 5-HT2BR mRNA on DRN GABAergic interneurons. Altogether, these results show that, in the rat DRN, 5-HT2BRs are located on GABAergic interneurons, and exert a tonic inhibitory control on 5-HT neurons innervating the mPFC.
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Affiliation(s)
- Adeline Cathala
- Inserm U1215, Neurocentre Magendie, Physiopathology and therapeutic approaches of stress-related diseases, Bordeaux F-33000, France; Université de Bordeaux, Bordeaux F-33000, France.
| | - Céline Devroye
- Inserm U1215, Neurocentre Magendie, Physiopathology and therapeutic approaches of stress-related diseases, Bordeaux F-33000, France; Université de Bordeaux, Bordeaux F-33000, France.
| | - Guillaume Drutel
- Inserm U1215, Neurocentre Magendie, Physiopathology and therapeutic approaches of stress-related diseases, Bordeaux F-33000, France; Université de Bordeaux, Bordeaux F-33000, France.
| | - Jean-Michel Revest
- Inserm U1215, Neurocentre Magendie, Physiopathology and therapeutic approaches of stress-related diseases, Bordeaux F-33000, France; Université de Bordeaux, Bordeaux F-33000, France.
| | - Francesc Artigas
- Department of Neurochemistry and Neuropharmacology, Institut d'Investigacions Biomèdiques de Barcelona, CSIC-IDIBAPS, Rosselló 161, 08036 Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Spain.
| | - Umberto Spampinato
- Inserm U1215, Neurocentre Magendie, Physiopathology and therapeutic approaches of stress-related diseases, Bordeaux F-33000, France; Université de Bordeaux, Bordeaux F-33000, France.
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22
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Ehlinger DG, Commons KG. Cav1.2 L-type calcium channels regulate stress coping behavior via serotonin neurons. Neuropharmacology 2018; 144:282-290. [PMID: 30176250 DOI: 10.1016/j.neuropharm.2018.08.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 08/23/2018] [Accepted: 08/25/2018] [Indexed: 01/15/2023]
Abstract
Human genetic variation in the gene CACNA1C, which codes for the alpha-1c subunit of Cav1.2 L-type calcium channels (LTCCs), has been broadly associated with enhanced risk for neuropsychiatric disorders including major depression, bipolar and schizophrenia. Little is known about the specific neural circuits through which CACNA1C and Cav1.2 LTCCs impact disease etiology. However, serotonin (5-HT) neurotransmission has been consistently implicated in these neuropsychiatric disorders and Cav1.2 LTCCs may influence 5-HT neuron activity during relevant behavioral states such as stress. We utilized a temporally controlled and 5-HT neuron specific Cacna1c knockout mouse model to assess stress-coping behavior using the forced swim test and dorsal raphe (DR) 5-HT neuron Fos activation. Furthermore, we assessed 5-HT1A receptor function and feedback inhibition of the DR following administration of the 5-HT1A antagonist WAY-100635. We find that 5-HT neuron Cacna1c knockout disrupts active-coping behavior in the forced swim test and that this behavioral effect is rescued by blocking 5-HT1A receptors. Moreover, Cacna1c knockout mice display enhanced Fos expression in caudal DR 5-HT neurons and an enhanced response to a 5-HT1A receptor antagonist in rostral DR 5-HT neurons, indicating that loss of Cacna1c disrupts both 5-HT neuron activation and 5-HT1A dependent feedback inhibition across the caudal to rostral DR. Collectively, these results reveal an important role for 5-HT neuron Cav1.2 LTCCs in stress-coping behavior and 5-HT1A receptor function. This suggests that alterations in CACNA1C function or expression could influence the development or treatment of neuropsychiatric disorder through serotonergic mechanisms.
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Affiliation(s)
- Daniel G Ehlinger
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Anesthesia, Harvard Medical School, Boston, MA, USA.
| | - Kathryn G Commons
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Anesthesia, Harvard Medical School, Boston, MA, USA
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23
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Ellegood J, Yee Y, Kerr TM, Muller CL, Blakely RD, Henkelman RM, Veenstra-VanderWeele J, Lerch JP. Analysis of neuroanatomical differences in mice with genetically modified serotonin transporters assessed by structural magnetic resonance imaging. Mol Autism 2018; 9:24. [PMID: 29651330 PMCID: PMC5894125 DOI: 10.1186/s13229-018-0210-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/21/2018] [Indexed: 02/03/2023] Open
Abstract
Background The serotonin (5-HT) system has long been implicated in autism spectrum disorder (ASD) as indicated by elevated whole blood and platelet 5-HT, altered platelet and brain receptor and transporter binding, and genetic linkage and association findings. Based upon work in genetically modified mice, 5-HT is known to influence several aspects of brain development, but systematic neuroimaging studies have not previously been reported. In particular, the 5-HT transporter (serotonin transporter, SERT; 5-HTT) gene, Slc6a4, has been extensively studied. Methods Using a 7-T MRI and deformation-based morphometry, we assessed neuroanatomical differences in an Slc6a4 knockout mouse on a C57BL/6 genetic background, along with an Slc6a4 Ala56 knockin mouse on two different genetic backgrounds (129S and C57BL/6). Results Individually (same sex, same background, same genotype), the only differences found were in the female Slc6a4 knockout mouse; all the others had no significant differences. However, an analysis of variance across the whole study sample revealed a significant effect of Slc6a4 on the amygdala, thalamus, dorsal raphe nucleus, and lateral and frontal cortices. Conclusions This work shows that an increase or decrease in SERT function has a significant effect on the neuroanatomy in 5-HT relevant regions, particularly the raphe nuclei. Notably, the Slc6a4 Ala56 knockin alone appears to have an insignificant, but suggestive, effect compared to the KO, which is consistent with Slc6a4 function. Despite the small number of 5-HT neurons and their localization to the brainstem, it is clear that 5-HT plays an important role in neuroanatomical organization. Electronic supplementary material The online version of this article (10.1186/s13229-018-0210-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jacob Ellegood
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada
| | - Yohan Yee
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
| | - Travis M Kerr
- 3Department of Psychiatry, Vanderbilt University, Nashville, TN 37235 USA
| | | | - Randy D Blakely
- 2Department of Pharmacology, Vanderbilt University, Nashville, TN 37235 USA.,3Department of Psychiatry, Vanderbilt University, Nashville, TN 37235 USA.,5Department of Biomedical Science and Brain Institute, Florida Atlantic University, Jupiter, FL 33431 USA
| | - R Mark Henkelman
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
| | - Jeremy Veenstra-VanderWeele
- 2Department of Pharmacology, Vanderbilt University, Nashville, TN 37235 USA.,6Department of Psychiatry, Columbia University, New York, NY 10027 USA
| | - Jason P Lerch
- 1Mouse Imaging Centre (MICe), Hospital for Sick Children, 25 Orde Street, Toronto, Ontario M5T 3H7 Canada.,4Department of Medical Biophysics, University of Toronto, Toronto, ON M5S Canada
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Mlinar B, Montalbano A, Waider J, Lesch KP, Corradetti R. Increased functional coupling of 5-HT 1A autoreceptors to GIRK channels in Tph2 -/- mice. Eur Neuropsychopharmacol 2017; 27:1258-1267. [PMID: 29126768 DOI: 10.1016/j.euroneuro.2017.10.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 10/14/2017] [Accepted: 10/22/2017] [Indexed: 10/18/2022]
Abstract
Firing activity of serotonergic neurons is under regulatory control by somatodendritic 5-HT1A autoreceptors (5-HT1AARs). Enhanced 5-HT1AAR functioning may cause decreased serotonergic signaling in brain and has thereby been implicated in the etiology of mood and anxiety disorders. Tryptophan hydroxylase-2 knockout (Tph2-/-) mice exhibit sensitization of 5-HT1A agonist-induced inhibition of serotonergic neuron firing and thus represents a unique animal model of enhanced 5-HT1AAR functioning. To elucidate the mechanisms underlying 5-HT1AAR supersensitivity in Tph2-/- mice, we characterized the activation of G protein-coupled inwardly-rectifying potassium (GIRK) conductance by the 5-HT1A receptor agonist 5-carboxamidotryptamine using whole-cell recordings from serotonergic neurons in dorsal raphe nucleus. Tph2-/- mice exhibited a mean twofold leftward shift of the agonist concentration-response curve (p < 0.001) whereas the maximal response, proportional to the 5-HT1AAR number, was not different (p = 0.42) compared to Tph2+/- and Tph2+/+ littermates. No differences were found in the basal inwardly-rectifying potassium conductance, determined in the absence of agonist, (p = 0.80) nor in total GIRK conductance activated by intracellular application of GTP-γ-S (p = 0.69). These findings indicate increased functional coupling of 5-HT1AARs to GIRK channels in Tph2-/- mice without a concomitant increase in 5-HT1AARs and/or GIRK channel density. In addition, no changes were found in α1-adrenergic facilitation of firing (p = 0.72) indicating lack of adaptive changes Tph2-/- mice. 5-HT1AAR supersensitivity may represents a previously unrecognized cause of serotonergic system hypofunction and associated disorders and provides a possible explanation for conflicting results on the correlation between 5-HT1AAR density and depression in clinical imaging studies.
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Affiliation(s)
- Boris Mlinar
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy.
| | - Alberto Montalbano
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Jonas Waider
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Center of Mental Health, University of Wuerzburg, Wuerzburg, Germany; Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia; Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
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Zahm DS, Root DH. Review of the cytology and connections of the lateral habenula, an avatar of adaptive behaving. Pharmacol Biochem Behav 2017; 162:3-21. [PMID: 28647565 PMCID: PMC5659881 DOI: 10.1016/j.pbb.2017.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 05/02/2017] [Accepted: 06/13/2017] [Indexed: 12/21/2022]
Abstract
The cytology and connections of the lateral habenula (LHb) are reviewed. The habenula is first introduced, after which the cytology of the LHb is discussed mainly with reference to cell types, general topography and descriptions of subnuclei. An overview of LHb afferent connections is given followed by some details about the projections to LHb from a number of structures. An overview of lateral habenula efferent connections is given followed by some details about the projections from LHb to a number of structures. In considering the afferent and efferent connections of the LHb some attention is given to the relative validity of regarding it as a bi-partite structure featuring 'limbic' and 'pallidal' parts. The paper ends with some concluding remarks about the relative place of the LHb in adaptive behaving.
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Affiliation(s)
- Daniel S Zahm
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, 1402 S. Grand Blvd., Saint Louis, MO 63104, United States.
| | - David H Root
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, United States.
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Maia GH, Brazete CS, Soares JI, Luz LL, Lukoyanov NV. Serotonin depletion increases seizure susceptibility and worsens neuropathological outcomes in kainate model of epilepsy. Brain Res Bull 2017; 134:109-20. [PMID: 28716398 DOI: 10.1016/j.brainresbull.2017.07.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 11/22/2022]
Abstract
Serotonin is implicated in the regulation of seizures, but whether or not it can potentiate the effects of epileptogenic factors is not fully established. Using the kainic acid model of epilepsy in rats, we tested the effects of serotonin depletion on (1) susceptibility to acute seizures, (2) development of spontaneous recurrent seizures and (3) behavioral and neuroanatomical sequelae of kainic acid treatment. Serotonin was depleted by pretreating rats with p-chlorophenylalanine. In different groups, kainic acid was injected at 3 different doses: 6.5mg/kg, 9.0mg/kg or 12.5mg/kg. A single dose of 6.5mg/kg of kainic acid reliably induced status epilepticus in p-chlorophenylalanine-pretreated rats, but not in saline-pretreated rats. The neuroexcitatory effects of kainic acid in the p-chlorophenylalanine-pretreated rats, but not in saline-pretreated rats, were associated with the presence of tonic-clonic convulsions and high lethality. Compared to controls, a greater portion of serotonin-depleted rats showed spontaneous recurrent seizures after kainic acid injections. Loss of hippocampal neurons and spatial memory deficits associated with kainic acid treatment were exacerbated by prior depletion of serotonin. The present findings are of particular importance because they suggest that low serotonin activity may represent one of the major risk factors for epilepsy and, thus, offer potentially relevant targets for prevention of epileptogenesis.
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Park HS, Lee JM, Cho HS, Park SS, Kim TW. Physical exercise ameliorates mood disorder-like behavior on high fat diet-induced obesity in mice. Psychiatry Res 2017; 250:71-7. [PMID: 28142069 DOI: 10.1016/j.psychres.2017.01.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/05/2016] [Accepted: 01/03/2017] [Indexed: 01/17/2023]
Abstract
Obesity is associated with mood disorders such as depression and anxiety. The aim of this study was to investigate whether treadmill exercise had any benefits on mood disorder by high fat diet (HFD) induced obesity. Mice were randomly divided into four groups: control, control and exercise, high fat diet (HFD), and HFD and exercise. Obesity was induced by a 20-week HFD (60%). In the exercise groups, exercise was performed 6 times a week for 12 weeks, with the exercise duration and intensity gradually increasing at 4-week intervals. Mice were tested in tail suspension and elevated plus maze tasks in order to verify the mood disorder like behavior such as depression and anxiety on obesity. In the present study, the number of 5-HT- and TPH-positive cells, and expression of 5-HT1A and 5-HTT protein decreased in dorsal raphe, and depression and anxiety like behavior increased in HFD group compared with the CON group. In contrast, treadmill exercise ameliorated mood disorder like behavior by HFD induced obesity and enhanced expression of the serotonergic system in the dorsal raphe. We concluded that exercise increases the capacity of the serotonergic system in the dorsal raphe, which improves the mood disorders associated with HFD-induced obesity.
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Holschbach MA, Lonstein JS. Motherhood and infant contact regulate neuroplasticity in the serotonergic midbrain dorsal raphe. Psychoneuroendocrinology 2017; 76:97-106. [PMID: 27898359 PMCID: PMC5272870 DOI: 10.1016/j.psyneuen.2016.10.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 10/03/2016] [Accepted: 10/25/2016] [Indexed: 12/22/2022]
Abstract
The adult brain shows remarkable neuroplasticity in response to hormones and the socioemotional modifications that they influence. In females with reproductive and maternal experience, this neuroplasticity includes the birth and death of cells in several forebrain regions involved in maternal caregiving and postpartum affective state. Such plasticity in midbrain sites critical for these behavioral and emotional processes has never been examined, though. By visualizing bromodeoxyuridine (BrdU) to label mitotic cells, NeuroD for neuronal precursors, and TUNEL to identify dying cells, we found that the midbrain dorsal raphe nucleus (DR, the source of most ascending serotoninergic projections) exhibited significant neuroplasticity in response to motherhood. Specifically, BrdU analyses revealed that DR newborn cell survival (but not proliferation) was regulated by reproductive state, such that cells born early postpartum were less likely to survive 12 days to reach the late postpartum period compared to cells born during late pregnancy that survived 12 days to reach the early postpartum period. Many of the surviving cells in the DR were NeuN immunoreactive, suggesting a neuronal phenotype. Consistent with these findings, late postpartum rats had fewer NeuroD-immunoreactive DR cells than early postpartum rats. Maternal experience contributed to the late postpartum reduction in DR newborn cell survival because removing the litter at parturition increased cell survival as well as reduced cell death. Unlike cytogenesis in the maternal hippocampus, which is reduced by circulating glucocorticoids, DR newborn cell survival was unaffected by postpartum adrenalectomy. These effects of reproductive state and motherhood on DR plasticity were associated with concurrent changes in DR levels of serotonin's precursor, 5-HTP, and its metabolite, 5-HIAA. Our results demonstrate for the first time that cytogenesis occurs in the midbrain DR of any adult mammal, that DR plasticity is influenced by female reproductive state and maternal experience, and that this plasticity is accompanied by changes in DR serotonergic function. Because serotonin is critical for postpartum caregiving behaviors and maternal affective state, plasticity in the DR may contribute to the neurochemical changes necessary for successful motherhood.
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Affiliation(s)
- M Allie Holschbach
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824, USA.
| | - Joseph S Lonstein
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824, USA
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Khalilzadeh E, Saiah GV. The possible mechanisms of analgesia produced by microinjection of morphine into the lateral habenula in the acute model of trigeminal pain in rats. Res Pharm Sci 2017. [PMID: 28626482 PMCID: PMC5465833 DOI: 10.4103/1735-5362.207205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This study aimed to assess the effect of intra-habenular injection of morphine on acute trigeminal pain in rats. Also here, we examined the involvement of raphe nucleus opioid and 5HT3 receptors on the antinociceptive activity of intra habenular morphine to explore the possibility of existence of descending antinociceptive relay between the habenula and raphe nucleus. The numbers of eye wiping response elicited by applying a drop (40 μL) of NaCl (5 M) solution on the corneal surface were taken as an index of acute trigeminal nociception. Intra habenular microinjection of morphine at a dose of 2 μg was without effect, whereas at doses of 5 and 8 μg significantly produced antinociception. Microinjection of naltrexone (4 μg) and ondansetron (1 μg) into the dorsal raphe nucleus prior to intra-habenular saline did not produce any significant effect on corneal pain perception. Pretreatment of the raphe nucleus with ondansetron but not naltrexone prevented intra habenular morphine (8 μg) induced antinociception. Also, intra habenular injection of lidocaine (2%, 0.5 μL reduced corneal pain response. Moreover, intra-habenular microinjection of L-glutamic acid (1 and 2 μg/site) did not produce any analgesic activity in this model of pain. In conclusion, the present results suggest that the activation of the habenular μ opioid receptor by microinjection of morphine or inhibition of habenular neurons by microinjection of lidocaine produced an analgesic effect in the acute trigeminal model of pain in rats. The analgesic effect of intra habenular morphine was blocked by intra-dorsal raphe injection of serotonin 5-HT3 antagonist.
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Affiliation(s)
- Emad Khalilzadeh
- Division of Physiology, Department of Basic Science, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, I.R. Iran
| | - Gholamreza Vafaei Saiah
- Division of Physiology, Department of Basic Science, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, I.R. Iran
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Kharas N, Whitt H, Reyes-Vasquez C, Dafny N. Methylphenidate modulates dorsal raphe neuronal activity: Behavioral and neuronal recordings from adolescent rats. Brain Res Bull 2016; 128:48-57. [PMID: 27889580 DOI: 10.1016/j.brainresbull.2016.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 01/09/2023]
Abstract
Methylphenidate (MPD) is a widely prescribed psychostimulants used for the treatment of attention deficit hyperactive disorder (ADHD). Unlike the psychostimulants cocaine and amphetamine, MPD does not exhibit direct actions on the serotonin transporter, however there is evidence suggesting that the therapeutic effects of MPD may be mediated in part by alterations in serotonin transmission. This study aimed to investigate the role of the dorsal raphe (DR) nucleus, one of the major sources of serotonergic innervation in the mammalian brain, in the response to MPD exposure. Freely behaving adolescent rats previously implanted bilaterally with permanent electrodes were used. An open field assay and a wireless neuronal recording system were used to concomitantly record behavioral and DR electrophysiological activity following acute and chronic MPD exposure. Four groups were used: one control (saline) and three experimental groups treated with 0.6, 2.5, and 10.0mg/kg MPD respectively. Animals received daily MPD or saline injections on experimental days 1-6, followed by 3 washout days and MPD rechallenge dose on experimental day (ED)10. The same chronic dose of MPD resulted in either behavioral sensitization or tolerance, and we found that neuronal activity recorded from the DR neuronal units of rats expressing behavioral sensitization to chronic MPD exposure responded significantly differently to MPD rechallenge on ED10 compared to the DR unit activity recorded from animals that expressed behavioral tolerance. This correlation between behavioral response and DR neuronal activity following chronic MPD exposure provides evidence that the DR is involved in the acute effects as well as the chronic effects of MPD in adolescent rats.
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Affiliation(s)
- Natasha Kharas
- The University of Texas Health Science Center, Medical School at Houston, Department of Neurobiology and Anatomy, 6431 Fannin St., MSB 7.208B, Houston, TX 77030, USA
| | - Holly Whitt
- The University of Texas Health Science Center, Medical School at Houston, Department of Neurobiology and Anatomy, 6431 Fannin St., MSB 7.208B, Houston, TX 77030, USA
| | - Cruz Reyes-Vasquez
- Departmento de Fisiologia Division de Investigacion Universidad Nacional Autonoma de Mexico Mexico City, Mexico
| | - Nachum Dafny
- The University of Texas Health Science Center, Medical School at Houston, Department of Neurobiology and Anatomy, 6431 Fannin St., MSB 7.208B, Houston, TX 77030, USA.
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Cohen JL, Ata AE, Jackson NL, Rahn EJ, Ramaker RC, Cooper S, Kerman IA, Clinton SM. Differential stress induced c-Fos expression and identification of region-specific miRNA-mRNA networks in the dorsal raphe and amygdala of high-responder/low-responder rats. Behav Brain Res 2016; 319:110-123. [PMID: 27865919 DOI: 10.1016/j.bbr.2016.11.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 10/19/2016] [Accepted: 11/08/2016] [Indexed: 01/03/2023]
Abstract
Chronic stress triggers a variety of physical and mental health problems, and how individuals cope with stress influences risk for emotional disorders. To investigate molecular mechanisms underlying distinct stress coping styles, we utilized rats that were selectively-bred for differences in emotionality and stress reactivity. We show that high novelty responding (HR) rats readily bury a shock probe in the defensive burying test, a measure of proactive stress coping behavior, while low novelty responding (LR) rats exhibit enhanced immobility, a measure of reactive coping. Shock exposure in the defensive burying test elicited greater activation of HR rats' caudal dorsal raphe serotonergic cells compared to LRs, but lead to more pronounced activation throughout LRs' amygdala (lateral, basolateral, central, and basomedial nuclei) compared to HRs. RNA-sequencing revealed 271 mRNA transcripts and 33 microRNA species that were differentially expressed in HR/LR raphe and amygdala. We mapped potential microRNA-mRNA networks by correlating and clustering mRNA and microRNA expression and identified networks that differed in either the HR/LR dorsal raphe or amygdala. A dorsal raphe network linked three microRNAs which were down-regulated in LRs (miR-206-3p, miR-3559-5p, and miR-378a-3p) to repression of genes related to microglia and immune response (Cd74, Cyth4, Nckap1l, and Rac2), the genes themselves were up-regulated in LR dorsal raphe. In the amygdala, another network linked miR-124-5p, miR-146a-5p, miR-3068-3p, miR-380-5p, miR-539-3p, and miR-7a-1-3p with repression of chromatin remodeling-related genes (Cenpk, Cenpq, Itgb3bp, and Mis18a). Overall this work highlights potential drivers of gene-networks and downstream molecular pathways within the raphe and amygdala that contribute to individual differences in stress coping styles and stress vulnerabilities.
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Affiliation(s)
- Joshua L Cohen
- Medical Scientist Training Program, University of Alabama-Birmingham, USA
| | - Anooshah E Ata
- University of Alabama-Birmingham School of Medicine, USA
| | - Nateka L Jackson
- Department of Neurobiology, University of Alabama-Birmingham, USA
| | - Elizabeth J Rahn
- Department of Neurobiology, University of Alabama-Birmingham, USA
| | - Ryne C Ramaker
- Medical Scientist Training Program, University of Alabama-Birmingham, USA; HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - Sara Cooper
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - Ilan A Kerman
- School of Neuroscience, Virginia Tech University, USA; Department of Psychiatry & Behavioral Medicine, Carilion Clinic, Virginia Tech Carilion School of Medicine, USA
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Haugas M, Tikker L, Achim K, Salminen M, Partanen J. Gata2 and Gata3 regulate the differentiation of serotonergic and glutamatergic neuron subtypes of the dorsal raphe. Development 2016; 143:4495-4508. [PMID: 27789623 DOI: 10.1242/dev.136614] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 10/18/2016] [Indexed: 12/18/2022]
Abstract
Serotonergic and glutamatergic neurons of the dorsal raphe regulate many brain functions and are important for mental health. Their functional diversity is based on molecularly distinct subtypes; however, the development of this heterogeneity is poorly understood. We show that the ventral neuroepithelium of mouse anterior hindbrain is divided into specific subdomains giving rise to serotonergic neurons as well as other types of neurons and glia. The newly born serotonergic precursors are segregated into distinct subpopulations expressing vesicular glutamate transporter 3 (Vglut3) or serotonin transporter (Sert). These populations differ in their requirements for transcription factors Gata2 and Gata3, which are activated in the post-mitotic precursors. Gata2 operates upstream of Gata3 as a cell fate selector in both populations, whereas Gata3 is important for the differentiation of the Sert+ precursors and for the serotonergic identity of the Vglut3+ precursors. Similar to the serotonergic neurons, the Vglut3-expressing glutamatergic neurons, located in the central dorsal raphe, are derived from neural progenitors in the ventral hindbrain and express Pet1 Furthermore, both Gata2 and Gata3 are redundantly required for their differentiation. Our study demonstrates lineage relationships of the dorsal raphe neurons and suggests that functionally significant heterogeneity of these neurons is established early during their differentiation.
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Affiliation(s)
- Maarja Haugas
- Department of Biosciences, P.O. Box 56, Viikinkaari 9, FIN00014-University of Helsinki, Helsinki, Finland
| | - Laura Tikker
- Department of Biosciences, P.O. Box 56, Viikinkaari 9, FIN00014-University of Helsinki, Helsinki, Finland
| | - Kaia Achim
- EMBL Developmental Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Marjo Salminen
- Department of Veterinary Biosciences, P.O. Box 66, Agnes Sjobergin katu 2, FIN00014-University of Helsinki, Helsinki, Finland
| | - Juha Partanen
- Department of Biosciences, P.O. Box 56, Viikinkaari 9, FIN00014-University of Helsinki, Helsinki, Finland
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Yoshimura Y, Ishikawa C, Kasegai H, Masuda T, Yoshikawa M, Shiga T. Roles of 5-HT 1A receptor in the expression of AMPA receptor and BDNF in developing mouse cortical neurons. Neurosci Res 2016; 115:13-20. [PMID: 27702575 DOI: 10.1016/j.neures.2016.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 09/13/2016] [Accepted: 09/21/2016] [Indexed: 11/29/2022]
Abstract
The possible interactions between serotonergic and glutamatergic systems during neural development and under the pathogenesis of depression remain unclear. We now investigated roles of 5-HT1A receptor in the mRNA expression of AMPA receptor subunits (GluR1 and GluR2) and brain-derived neurotrophic factor (BDNF) using primary culture of cerebral cortex of mouse embryos. Neurons at embryonic day 18 were cultured for 3days or 14days and then treated with 5-HT1A receptor agonist (8-OH-DPAT) for 3h or 24h. In neurons cultured for 3 days, 8-OH-DPAT treatment for both 3h and 24h increased the mRNA levels of BDNF and GluR1, but not GluR2. In neurons cultured for 14 days, however, 8-OH-DPAT had no effects on these mRNA levels. Next, we examined in vivo roles of 5-HT1A receptor by administration of 8-OH-DPAT to newborn mice. Twenty-four hours after the oral administration of 8-OH-DPAT, the mRNA expression of BDNF was decreased in the frontal cortex, but had no effects on the mRNA expression of GluR1 and GluR2. Taken together, the present study suggests that 5-HT1A receptor activation modulates mRNA expression of AMPA receptor subunit and BDNF in cortical neurons, and the effects are different between in vitro and in vivo.
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Affiliation(s)
- Yuko Yoshimura
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
| | - Chihiro Ishikawa
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
| | - Haruki Kasegai
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
| | - Tomoyuki Masuda
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan; Department of Neurobiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
| | - Masaaki Yoshikawa
- Division of Anatomical Science, Department of Functional Morphology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi, Tokyo 173-8610, Japan
| | - Takashi Shiga
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan; Department of Neurobiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan.
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Mika A, Rumian N, Loughridge AB, Fleshner M. Exercise and Prebiotics Produce Stress Resistance: Converging Impacts on Stress-Protective and Butyrate-Producing Gut Bacteria. Int Rev Neurobiol 2016; 131:165-91. [PMID: 27793217 DOI: 10.1016/bs.irn.2016.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The gut microbial ecosystem can mediate the negative health impacts of stress on the host. Stressor-induced disruptions in microbial ecology (dysbiosis) can lead to maladaptive health effects, while certain probiotic organisms and their metabolites can protect against these negative impacts. Prebiotic diets and exercise are feasible and cost-effective strategies that can increase stress-protective bacteria and produce resistance against the detrimental behavioral and neurobiological impacts of stress. The goal of this review is to describe research demonstrating that both prebiotic diets and exercise produce adaptations in gut ecology and the brain that arm the organism against inescapable stress-induced learned helplessness. The results of this research support the novel hypothesis that some of the stress-protective effects of prebiotics and exercise are due to increases in stress-protective gut microbial species and their metabolites. In addition, new evidence also suggests that prebiotic diet or exercise interventions are most effective if given early in life (juvenile-adolescence) when both the gut microbial ecosystem and the brain are plastic. Based on our new understanding of the mechanistic convergence of these interventions, it is feasible to propose that in adults, both interventions delivered in combination may elevate their efficacy to promote a stress-resistant phenotype.
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Roh JH, Ko IG, Kim SE, Lee JM, Ji ES, Kim JH, Chang HK, Lee SK, Kim KH. Treadmill exercise ameliorates intracerebral hemorrhage-induced depression in rats. J Exerc Rehabil 2016; 12:299-307. [PMID: 27656626 PMCID: PMC5031381 DOI: 10.12965/jer.1632692.346] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 07/23/2016] [Indexed: 11/24/2022] Open
Abstract
Intracerebral hemorrhage (ICH) is a severe type of stroke causing neurological dysfunction with high mortality rate. Depression is one of the most common complications of ICH. In the present study, the effects of treadmill exercise on ICH-induced depressive symptoms in relation with apoptosis were investigated using rats. ICH rat model was induced by injection of collagenase into the hippocampus using stereotaxic instrument. Open field test for activity and forced swimming test for depressive symptoms were conducted. Apoptosis in the hippocampus was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunohistochemistry for caspase-3, and western blot for Bcl-2 and Bax. Western blot analysis for 5-hydroxy-tryptamine (5-HT, serotonin) and tryptophan hydroxylase (TPH) in the dorsal raphe was also conducted for biomarkers of depression. In the present results, immobility time was increased and climbing time was decreased by induction of ICH and treadmill exercise inhibited immobility time and increased climbing time in ICH rats. DNA fragmentation and caspase-3 expression in the hippocampal dentate gyrus were enhanced by induction of ICH and treadmill exercise suppressed ICH-induced DNA fragmentation and caspase-3 expression. Bax expression in the hippocampus was increased by induction of ICH and treadmill exercise inhibited Bax expression in the ICH rats. Expressions of 5-HT and TPH in the dorsal raphe were decreased by induction of ICH and treadmill exercise increased expressions of 5-HT and TPH in the ICH rats. In the present study, treadmill exercise ameliorated depressive symptoms through inhibiting apoptosis.
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Affiliation(s)
- Joo Hwan Roh
- Department of Urology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Korea
| | - Il-Gyu Ko
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Sung-Eun Kim
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Jae-Min Lee
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Eun-Sang Ji
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Ju Ho Kim
- Department of Urology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Korea
| | - Hyun-Kyung Chang
- Department of Urology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Korea
| | - Seung Kyu Lee
- Department of Urology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Korea
| | - Khae Hawn Kim
- Department of Urology, Gachon University Gil Medical Center, Gachon University School of Medicine, Incheon, Korea
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Johnson PL, Molosh A, Fitz SD, Arendt D, Deehan GA, Federici LM, Bernabe C, Engleman EA, Rodd ZA, Lowry CA, Shekhar A. Pharmacological depletion of serotonin in the basolateral amygdala complex reduces anxiety and disrupts fear conditioning. Pharmacol Biochem Behav 2016; 138:174-9. [PMID: 26476009 DOI: 10.1016/j.pbb.2015.09.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 01/12/2023]
Abstract
The basolateral and lateral amygdala nuclei complex (BLC) is implicated in a number of emotional responses including conditioned fear and social anxiety. Based on previous studies demonstrating that enhanced serotonin release in the BLC leads to increased anxiety and fear responses, we hypothesized that pharmacologically depleting serotonin in the BLC using 5,7-dihydroxytryptamine (5,7-DHT) injections would lead to diminished anxiety and disrupted fear conditioning. To test this hypothesis, 5,7-DHT(a serotonin-depleting agent) was bilaterally injected into the BLC. Desipramine (a norepinephrine reuptake inhibitor) was systemically administered to prevent non-selective effects on norepinephrine. After 5days, 5-7-DHT-treated rats showed increases in the duration of social interaction (SI) time, suggestive of reduced anxiety-like behavior. We then used a cue-induced fear conditioning protocol with shock as the unconditioned stimulus and tone as the conditioned stimulus for rats pretreated with bilateral 5,7-DHT, or vehicle, injections into the BLC. Compared to vehicle-treated rats, 5,7-DHT rats had reduced acquisition of fear during conditioning (measured by freezing time during tone), also had reduced fear retrieval/recall on subsequent testing days. Ex vivo analyses revealed that 5,7-DHT reduced local 5-HT concentrations in the BLC by ~40% without altering local norepinephrine or dopamine concentrations. These data provide additional support for 5-HT playing a critical role in modulating anxiety-like behavior and fear-associated memories through its actions within the BLC.
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Affiliation(s)
- Philip L Johnson
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA,.
| | - Andrei Molosh
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Stephanie D Fitz
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Dave Arendt
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gerald A Deehan
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Lauren M Federici
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cristian Bernabe
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Eric A Engleman
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Zachary A Rodd
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Christopher A Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Anantha Shekhar
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
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Petschner P, Juhasz G, Tamasi V, Adori C, Tothfalusi L, Hökfelt T, Bagdy G. Chronic venlafaxine treatment fails to alter the levels of galanin system transcripts in normal rats. Neuropeptides 2016; 57:65-70. [PMID: 26891823 DOI: 10.1016/j.npep.2016.01.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 01/22/2016] [Accepted: 01/31/2016] [Indexed: 11/16/2022]
Abstract
It is widely accepted that efficacy and speed of current antidepressants' therapeutic effect are far from optimal. Thus, there is a need for the development of antidepressants with new mechanisms of action. The neuropeptide galanin and its receptors (GalR1, GalR2 and GalR3) are among the promising targets. However, it is not clear whether or not the galanin system is involved in the antidepressant effect exerted by the currently much used inhibitors of the reuptake of serotonin and/or noradrenaline. To answer this question we administered the selective serotonin and noradrenaline reuptake inhibitor (SNRI) venlafaxine (40mg/kg/day via osmotic minipumps) to normal rats and examined the levels of the transcripts for galanin and GalR1-3 after a 3-week venlafaxine treatment in the dorsal raphe, hippocampus and frontal cortex. These areas are known to be involved in the effects of antidepressants and in depression itself. Venlafaxine failed to alter the expression of any of the galanin system genes in these areas. Our results show that one of the most efficient, currently used SNRIs does not alter transcript levels of galanin or its three receptors in normal rats. These findings suggest that the pro- and antidepressive-like effects of galanin reported in animal experiments may employ a novel mechanism(s).
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Affiliation(s)
- Peter Petschner
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Gabriella Juhasz
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE-NAP B Genetic Brain Imaging Migraine Research Group, Hungarian Academy of Sciences, Semmelweis University, Hungary
| | - Viola Tamasi
- Department of Genetics-, Cell and Immunobiology, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Csaba Adori
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; Retzius Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden
| | - Laszlo Tothfalusi
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Tomas Hökfelt
- Retzius Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden
| | - Gyorgy Bagdy
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary.
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Abstract
Forebrain serotonin relevant for many psychological disorders arises in the hindbrain, primarily within the dorsal and median raphe nuclei (DR and MR). These nuclei are heterogeneous, containing several distinct groups of serotonin neurons. Here, new insight into the afferent and efferent connectivity of these areas is reviewed in correlation with their developmental origin. These data suggest that the caudal third of the DR, the area originally designated B6, may be misidentified as part of the DR as it shares many features of connectivity with the MR. By considering the rostral DR independently and affiliating the B6 to the MR, the diverse subgroups of serotonin neurons can be arranged with more coherence into two umbrella groups, each with distinctive domains of influence. Serotonin neurons within the rostral DR are uniquely interconnected with brain areas associated with emotion and motivation such as the amygdala, accumbens and ventral pallidum. In contrast serotonin neurons in the B6 and MR are characterized by their dominion over the septum and hippocampus. This distinction between the DR and B6/MR parallels their developmental origin and likely impacts their role in both behavior and psychopathology. Implications and further subdivisions within these areas are discussed.
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Affiliation(s)
- Kathryn G Commons
- Department of Anesthesiology, Perioperative, and Pain Medicine, Boston Children's Hospital, 300 Longwood Ave., Boston, MA, 02115, USA. .,Department of Anaesthesia, Harvard Medical School, Boston, USA.
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Krzyżanowska M, Steiner J, Brisch R, Mawrin C, Busse S, Braun K, Jankowski Z, Bernstein HG, Bogerts B, Gos T. Ribosomal DNA transcription in dorsal raphe nucleus neurons is increased in residual schizophrenia compared to depressed patients with affective disorders. Psychiatry Res 2015; 230:233-41. [PMID: 26350704 DOI: 10.1016/j.psychres.2015.08.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 08/13/2015] [Accepted: 08/30/2015] [Indexed: 11/15/2022]
Abstract
The central serotonergic system is implicated differentially in the pathogenesis of depression and schizophrenia. The dorsal raphe nucleus (DRN) is the main source of serotonergic innervation of forebrain limbic structures disturbed in both disorders. The study was carried out on paraffin-embedded brains from 27 depressed (15 major depressive disorder, MDD and 12 bipolar disorder, BD) and 17 schizophrenia (9 residual and 8 paranoid) patients and 28 matched controls without mental disorders. The transcriptional activity of ribosomal DNA (rDNA) in DRN neurons was evaluated by the AgNOR silver staining method. A significant effect of diagnosis on rDNA activity was found in the cumulative analysis of all DRN subnuclei. Further analysis revealed an increase in this activity in residual (but not paranoid) schizophrenia compared to depressed (both MDD and BD) patients. The effect was most probably neither confounded by suicide nor related to antidepressant and antipsychotic medication. Our findings suggest that increased activity of rDNA in DRN neurons is a distinct phenomenon in residual schizophrenia, related presumably to differentially disturbed inputs to the DRN and/or their local transformation compared with depressive episodes in patients with affective disorders.
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Affiliation(s)
- Marta Krzyżanowska
- Department of Forensic Medicine, Medical University of Gdańsk, ul. Dębowa 23, 80-204 Gdańsk, Poland
| | - Johann Steiner
- Department of Psychiatry, Otto-von-Guericke-University, Magdeburg, Germany
| | - Ralf Brisch
- Department of Forensic Medicine, Medical University of Gdańsk, ul. Dębowa 23, 80-204 Gdańsk, Poland
| | - Christian Mawrin
- Institute of Neuropathology, Otto-von-Guericke-University, Magdeburg, Germany
| | - Stefan Busse
- Department of Psychiatry, Otto-von-Guericke-University, Magdeburg, Germany
| | - Katharina Braun
- Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany
| | - Zbigniew Jankowski
- Department of Forensic Medicine, Medical University of Gdańsk, ul. Dębowa 23, 80-204 Gdańsk, Poland
| | | | - Bernhard Bogerts
- Department of Psychiatry, Otto-von-Guericke-University, Magdeburg, Germany
| | - Tomasz Gos
- Department of Forensic Medicine, Medical University of Gdańsk, ul. Dębowa 23, 80-204 Gdańsk, Poland; Department of Psychiatry, Otto-von-Guericke-University, Magdeburg, Germany; Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany.
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Montalbano A, Waider J, Barbieri M, Baytas O, Lesch KP, Corradetti R, Mlinar B. Cellular resilience: 5-HT neurons in Tph2(-/-) mice retain normal firing behavior despite the lack of brain 5-HT. Eur Neuropsychopharmacol 2015; 25:2022-35. [PMID: 26409296 DOI: 10.1016/j.euroneuro.2015.08.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/23/2015] [Accepted: 08/27/2015] [Indexed: 11/24/2022]
Abstract
Considerable evidence links dysfunction of serotonin (5-hydroxytryptamine, 5-HT) transmission to neurodevelopmental and psychiatric disorders characterized by compromised "social" cognition and emotion regulation. It is well established that the brain 5-HT system is under autoregulatory control by its principal transmitter 5-HT via its effects on activity and expression of 5-HT system-related proteins. To examine whether 5-HT itself also has a crucial role in the acquisition and maintenance of characteristic rhythmic firing of 5-HT neurons, we compared their intrinsic electrophysiological properties in mice lacking brain 5-HT, i.e. tryptophan hydroxylase-2 null mice (Tph2(-/-)) and their littermates, Tph2(+/-) and Tph2(+/+), by using whole-cell patch-clamp recordings in a brainstem slice preparation and single unit recording in anesthetized animals. We report that the active properties of dorsal raphe nucleus (DRN) 5-HT neurons in vivo (firing rate magnitude and variability; the presence of spike doublets) and in vitro (firing in response to depolarizing current pulses; action potential shape) as well as the resting membrane potential remained essentially unchanged across Tph2 genotypes. However, there were subtle differences in subthreshold properties, most notably, an approximately 25% higher input conductance in Tph2(-/-) mice compared with Tph2(+/-) and Tph2(+/+) littermates (p<0.0001). This difference may at least in part be a consequence of slightly bigger size of the DRN 5-HT neurons in Tph2(-/-) mice (approximately 10%, p<0.0001). Taken together, these findings show that 5-HT neurons acquire and maintain their signature firing properties independently of the presence of their principal neurotransmitter 5-HT, displaying an unexpected functional resilience to complete brain 5-HT deficiency.
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Affiliation(s)
- Alberto Montalbano
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Jonas Waider
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Mario Barbieri
- Department of Medical Sciences, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Ozan Baytas
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg, Germany
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Boris Mlinar
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy.
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Fakhoury M, Rompré PP, Boye SM. Role of the dorsal diencephalic conduction system in the brain reward circuitry. Behav Brain Res 2016; 296:431-41. [PMID: 26515931 DOI: 10.1016/j.bbr.2015.10.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 12/13/2022]
Abstract
Previous work with psychophysically based studies suggests that electrolytic lesion of the habenula, which lies in the dorsal diencephalic conduction system (DDC), degrades the intracranial self-stimulation (ICSS). This experiment was aimed at studying the importance of the DDC in brain stimulation reward, and its connections with other areas that support operant responding for brain stimulation. For this purpose, rats were implanted with stimulating electrodes at the dorsal raphe (DR) and lateral hypothalamus (LH), and lesioning electrodes in the medial forebrain bundle (MFB) and the DDC. Rats were trained to self-administer the stimulation at three different current intensities and were tested daily for changes in reward thresholds, defined as the pulse frequency required for half-maximal responding. The lesions were done at the DDC and the MFB, and were separated by two weeks interval during which the rats were tested for self-stimulation. At the end of the experiment, rats were transcardially perfused and their brains collected to determine the extent of the lesions and the locations of the stimulation sites. Results show that lesions at both the DDC and MFB produce larger and longer-lasting increases in the reward thresholds (upto 0.40 log10 units) than lesions at either pathway alone (upto 0.25 log10 units), and were more effective in attenuating the reward induced by the LH stimulation. These results suggest that there exist two parallel pathways, the MFB and the DDC, which could constitute a viable route for the reward signal triggered by ICSS.
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Bethea CL, Kohama SG, Reddy AP, Urbanski HF. Ovarian steroids regulate gene expression in the dorsal raphe of old female macaques. Neurobiol Aging 2015; 37:179-191. [PMID: 26686671 DOI: 10.1016/j.neurobiolaging.2015.10.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 09/18/2015] [Accepted: 10/05/2015] [Indexed: 11/18/2022]
Abstract
With extended life spans in modern humans, menopause has become a significant risk factor for depression, anxiety, loss of cognitive functions, weight gain, metabolic disease, osteoporosis, cardiovascular disease, and neurodegenerative diseases. Clinical studies have found beneficial neural effects of ovarian steroid hormone therapy (HT) during the menopausal transition and data are emerging that it can be continued long term. To further understand molecular underpinnings of the clinical studies, we used quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) to examine gene expression in the serotonergic dorsal raphe of old (>18 years) rhesus macaques, focusing on genes related to depression, cellular resilience, and neurodegenerative diseases. The animals were ovariectomized (Ovx, surgically menopausal) and subjected to either estradiol or estradiol plus progesterone HT, or to placebo, starting 2 months after Ovx and continuing for ∼ 4 years. Significant changes were observed in 36 of 48 genes examined that encode proteins supporting serotonin neurotransmission, synapse assembly, glutamate neurotransmission, DNA repair, chaperones, ubiquinases and transport motors, as well as genes encoding proteins that have potential to delay the onset of neuropathologies. The data reveal important gene targets for chronic HT that contribute to neural health. Alternatively, the loss of ovarian steroids may lead to loss of functions at the gene level that contribute to many of the observable neural deficits after menopause.
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Affiliation(s)
- Cynthia L Bethea
- Division of Reproductive Sciences, Oregon National Primate Research Center, Beaverton, OR, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA; Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR, USA.
| | - Steven G Kohama
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA
| | - Arubala P Reddy
- Division of Reproductive Sciences, Oregon National Primate Research Center, Beaverton, OR, USA; Department of Internal Medicine, Texas Tech Health Science Center, Lubbock, TX, USA
| | - Henryk F Urbanski
- Division of Reproductive Sciences, Oregon National Primate Research Center, Beaverton, OR, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA; Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, USA
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Alter SP, Stout KA, Lohr KM, Taylor TN, Shepherd KR, Wang M, Guillot TS, Miller GW. Reduced vesicular monoamine transport disrupts serotonin signaling but does not cause serotonergic degeneration. Exp Neurol 2015; 275 Pt 1:17-24. [PMID: 26428905 DOI: 10.1016/j.expneurol.2015.09.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/11/2015] [Accepted: 09/26/2015] [Indexed: 10/23/2022]
Abstract
We previously demonstrated that mice with reduced expression of the vesicular monoamine transporter 2 (VMAT2 LO) undergo age-related degeneration of the catecholamine-producing neurons of the substantia nigra pars compacta and locus ceruleus and exhibit motor disturbances and depressive-like behavior. In this work, we investigated the effects of reduced vesicular transport on the function and viability of serotonin neurons in these mice. Adult (4-6 months of age), VMAT2 LO mice exhibit dramatically reduced (90%) serotonin release capacity, as measured by fast scan cyclic voltammetry. We observed changes in serotonin receptor responsivity in in vivo pharmacological assays. Aged (months) VMAT2 LO mice exhibited abolished 5-HT1A autoreceptor sensitivity, as determined by 8-OH-DPAT (0.1 mg/kg) induction of hypothermia. When challenged with the 5HT2 agonist, 2,5-dimethoxy-4-iodoamphetamine (1 mg/kg), VMAT2 LO mice exhibited a marked increase (50%) in head twitch responses. We observed sparing of serotonergic terminals in aged mice (18-24 months) throughout the forebrain by SERT immunohistochemistry and [(3)H]-paroxetine binding in striatal homogenates of aged VMAT2 LO mice. In contrast to their loss of catecholamine neurons of the substantia nigra and locus ceruleus, aged VMAT2 LO mice do not exhibit a change in the number of serotonergic (TPH2+) neurons within the dorsal raphe, as measured by unbiased stereology at 26-30 months. Collectively, these data indicate that reduced vesicular monoamine transport significantly disrupts serotonergic signaling, but does not drive degeneration of serotonin neurons.
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Affiliation(s)
- Shawn P Alter
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Kristen A Stout
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Kelly M Lohr
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Tonya N Taylor
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Kennie R Shepherd
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Minzheng Wang
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Thomas S Guillot
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Gary W Miller
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States; Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, GA, United States.
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Challis C, Berton O. Top-Down Control of Serotonin Systems by the Prefrontal Cortex: A Path toward Restored Socioemotional Function in Depression. ACS Chem Neurosci 2015; 6:1040-54. [PMID: 25706226 DOI: 10.1021/acschemneuro.5b00007] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Social withdrawal, increased threat perception, and exaggerated reassurance seeking behaviors are prominent interpersonal symptoms in major depressive disorder (MDD). Altered serotonin (5-HT) systems and corticolimbic dysconnectivity have long been suspected to contribute to these symptomatic facets; however, the underlying circuits and intrinsic cellular mechanisms that control 5-HT output during socioemotional interactions remain poorly understood. We review literature that implicates a direct pathway between the ventromedial prefrontal cortex (vmPFC) and dorsal raphe nucleus (DRN) in the adaptive and pathological control of social approach-avoidance behaviors. Imaging and neuromodulation during approach-avoidance tasks in humans point to the cortical control of brainstem circuits as an essential regulator of socioemotional decisions and actions. Parallel rodent studies using viral-based connectomics and optogenetics are beginning to provide a cellular blueprint of the underlying circuitry. In these studies, manipulations of vmPFC synaptic inputs to the DRN have revealed bidirectional influences on socioaffective behaviors via direct monosynaptic excitation and indirect disynaptic inhibition of 5-HT neurons. Additionally, adverse social experiences that result in permanent avoidance biases, such as social defeat, drive long-lasting plasticity in this microcircuit, potentiating the indirect inhibition of 5-HT output. Conversely, neuromodulation of the vmPFC via deep brain stimulation (DBS) attenuates avoidance biases by restoring the direct excitatory drive of 5-HT neurons and strengthening a key subset of forebrain 5-HT projections. Better understanding the cellular organization of the vmPFC-DRN pathway and identifying molecular determinants of its neuroplasticity can open fundamentally novel avenues for the treatment of affective disorders.
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Affiliation(s)
- Collin Challis
- Department of Psychiatry, ‡Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Olivier Berton
- Department of Psychiatry, ‡Neuroscience Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
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Spiacci A, Pobbe RLH, Matthiesen M, Zangrossi H. 5-HT1A receptors of the rat dorsal raphe lateral wings and dorsomedial subnuclei differentially control anxiety- and panic-related defensive responses. Neuropharmacology 2015; 107:471-479. [PMID: 26145183 DOI: 10.1016/j.neuropharm.2015.06.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 06/24/2015] [Accepted: 06/27/2015] [Indexed: 01/04/2023]
Abstract
The dorsal raphe nucleus (DR), the main source of 5-HT projections to brain areas involved in anxiety regulation, is composed by 5 subnuclei that differ morphologically, functionally and neurochemically. Based on immunohistochemical evidence, it has been proposed that whereas 5-HT cells of the dorsomedial (dmDR) and caudal subnuclei are implicated in the pathophysiology of generalized anxiety disorder (GAD), neurons of the lateral wings (lwDR) are associated with panic disorder (PD). We here tested this hypothesis from a behavioral perspective by investigating the consequences of the non-selective stimulation of neurons within the dmDR and lwDR, or the pharmacological manipulation of 5-HT1A receptors located in these nuclei, of male Wistar rats exposed to the elevated T-maze. This test allows the measurement of both a GAD- (i.e. inhibitory avoidance) and a PD- (i.e. escape) related response in the same animal. Intra-dmDR injection of either the excitatory amino acid kainic acid or the 5-HT1A receptor antagonist WAY-100635 facilitated inhibitory avoidance acquisition, suggesting an anxiogenic effect, and inhibited escape expression, a panicolytic-like effect. Microinjection of the 5-HT1A receptor agonist 8-OH-DPAT caused the opposite effect. Administration of the same drugs into the lwDR only altered escape performance. Whereas kainic acid and 8-OH-DPAT facilitated its expression, WAY-100635 inhibited it. At higher doses, kainic acid administration evoked vigorous escape reactions as measured in an open-field. These findings implicate 5-HT neurons of the dmDR in the regulation of both GAD- and PD-related defensive behaviors. They also support a primary role of the lwDR in the mediation of PD-associated responses.
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Affiliation(s)
- Ailton Spiacci
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil
| | - Roger Luis Henschel Pobbe
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil
| | - Melina Matthiesen
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil
| | - Helio Zangrossi
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, São Paulo, Brazil.
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Beliveau V, Svarer C, Frokjaer VG, Knudsen GM, Greve DN, Fisher PM. Functional connectivity of the dorsal and median raphe nuclei at rest. Neuroimage 2015; 116:187-95. [PMID: 25963733 DOI: 10.1016/j.neuroimage.2015.04.065] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/31/2015] [Accepted: 04/28/2015] [Indexed: 10/23/2022] Open
Abstract
Serotonin (5-HT) is a neurotransmitter critically involved in a broad range of brain functions and implicated in the pathophysiology of neuropsychiatric illnesses including major depression, anxiety and sleep disorders. Despite being widely distributed throughout the brain, there is limited knowledge on the contribution of 5-HT to intrinsic brain activity. The dorsal raphe (DR) and median raphe (MR) nuclei are the source of most serotonergic neurons projecting throughout the brain and thus provide a compelling target for a seed-based probe of resting-state activity related to 5-HT. Here we implemented a novel multimodal neuroimaging approach for investigating resting-state functional connectivity (FC) between DR and MR and cortical, subcortical and cerebellar target areas. Using [(11)C]DASB positron emission tomography (PET) images of the brain serotonin transporter (5-HTT) combined with structural MRI from 49 healthy volunteers, we delineated DR and MR and performed a seed-based resting-state FC analysis. The DR and MR seeds produced largely similar FC maps: significant positive FC with brain regions involved in cognitive and emotion processing including anterior cingulate, amygdala, insula, hippocampus, thalamus, basal ganglia and cerebellum. Significant negative FC was observed within pre- and postcentral gyri for the DR but not for the MR seed. We observed a significant association between DR and MR FC and regional 5-HTT binding. Our results provide evidence for a resting-state network related to DR and MR and comprising regions receiving serotonergic innervation and centrally involved in 5-HT related behaviors including emotion, cognition and reward processing. These findings provide a novel advance in estimating resting-state FC related to 5-HT signaling, which can benefit our understanding of its role in behavior and neuropsychiatric illnesses.
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Affiliation(s)
- Vincent Beliveau
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Rigshospitalet, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claus Svarer
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Rigshospitalet, Copenhagen, Denmark
| | - Vibe G Frokjaer
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Rigshospitalet, Copenhagen, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Rigshospitalet, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Douglas N Greve
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Patrick M Fisher
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Rigshospitalet, Copenhagen, Denmark.
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Llamosas N, Bruzos-Cidón C, Rodríguez JJ, Ugedo L, Torrecilla M. Deletion of GIRK2 Subunit of GIRK Channels Alters the 5-HT1A Receptor-Mediated Signaling and Results in a Depression-Resistant Behavior. Int J Neuropsychopharmacol 2015; 18:pyv051. [PMID: 25956878 PMCID: PMC4756724 DOI: 10.1093/ijnp/pyv051] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 05/04/2015] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Targeting dorsal raphe 5-HT1A receptors, which are coupled to G-protein inwardly rectifying potassium (GIRK) channels, has revealed their contribution not only to behavioral and functional aspects of depression but also to the clinical response to its treatment. Although GIRK channels containing GIRK2 subunits play an important role controlling excitability of several brain areas, their impact on the dorsal raphe activity is still unknown. Thus, the goal of the present study was to investigate the involvement of GIRK2 subunit-containing GIRK channels in depression-related behaviors and physiology of serotonergic neurotransmission. METHODS Behavioral, functional, including in vivo extracellular recordings of dorsal raphe neurons, and neurogenesis studies were carried out in wild-type and GIRK2 mutant mice. RESULTS Deletion of the GIRK2 subunit promoted a depression-resistant phenotype and determined the behavioral response to the antidepressant citalopram without altering hippocampal neurogenesis. In dorsal raphe neurons of GIRK2 knockout mice, and also using GIRK channel blocker tertiapin-Q, the basal firing rate was higher than that obtained in wild-type animals, although no differences were observed in other firing parameters. 5-HT1A receptors were desensitized in GIRK2 knockout mice, as demonstrated by a lower sensitivity of dorsal raphe neurons to the inhibitory effect of the 5-HT1A receptor agonist, 8-OH-DPAT, and the antidepressant citalopram. CONCLUSIONS Our results indicate that GIRK channels formed by GIRK2 subunits determine depression-related behaviors as well as basal and 5-HT1A receptor-mediated dorsal raphe neuronal activity, becoming alternative therapeutic targets for psychiatric diseases underlying dysfunctional serotonin transmission.
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Affiliation(s)
| | | | | | | | - Maria Torrecilla
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of the Basque Country UPV/EHU, Leioa, Spain (Drs Llamosas, Bruzos-Cidón, Ugedo, and Torrecilla); Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain (Dr Rodríguez); Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain (Dr Rodríguez).
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Muzerelle A, Scotto-Lomassese S, Bernard JF, Soiza-Reilly M, Gaspar P. Conditional anterograde tracing reveals distinct targeting of individual serotonin cell groups (B5-B9) to the forebrain and brainstem. Brain Struct Funct 2016; 221:535-61. [PMID: 25403254 DOI: 10.1007/s00429-014-0924-4] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/16/2014] [Indexed: 01/10/2023]
Abstract
Serotoninergic innervation of the central nervous system is provided by hindbrain raphe nuclei (B1–B9). The extent to which each raphe subdivision has distinct topographic organization of their projections is still unclear. We provide a comprehensive description of the main targets of the rostral serotonin (5-HT) raphe subgroups (B5–B9) in the mouse brain. Adeno-associated viruses that conditionally express GFP under the control of the 5-HT transporter promoter were used to label small groups of 5-HT neurons in the dorsal (B7d), ventral (B7v), lateral (B7l), and caudal (B6) subcomponents of the dorsal raphe (DR) nucleus as well as in the rostral and caudal parts of the median raphe (MR) nucleus (B8 and B5, respectively), and in the supralemniscal (B9) cell group. We illustrate the distinctive and largely non-overlapping projection areas of these cell groups: for instance, DR (B7) projects to basal parts of the forebrain, such as the amygdala, whereas MR (B8) is the main 5-HT source to the hippocampus, septum, and mesopontine tegmental nuclei. Distinct subsets of B7 have preferential brain targets: B7v is the main source of 5-HT for the cortex and amygdala while B7d innervates the hypothalamus. We reveal for the first time the target areas of the B9 cell group, demonstrating projections to the caudate, prefrontal cortex, substantia nigra, locus coeruleus and to the raphe cell groups. The broad topographic organization of the different raphe subnuclei is likely to underlie the different functional roles in which 5-HT has been implicated in the brain. The present mapping study could serve as the basis for genetically driven specific targeting of the different subcomponents of the mouse raphe system.
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Bruzos-Cidón C, Miguelez C, Rodríguez JJ, Gutiérrez-Lanza R, Ugedo L, Torrecilla M. Altered neuronal activity and differential sensitivity to acute antidepressants of locus coeruleus and dorsal raphe nucleus in Wistar Kyoto rats: a comparative study with Sprague Dawley and Wistar rats. Eur Neuropsychopharmacol 2014; 24:1112-22. [PMID: 24582527 DOI: 10.1016/j.euroneuro.2014.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 12/27/2022]
Abstract
The Wistar Kyoto rat (WKY) has been proposed as an animal model of depression. The noradrenergic nucleus, locus coeruleus (LC) and the serotonergic nucleus, dorsal raphe (DRN) have been widely implicated in the ethiopathology of this disease. Thus, the goal of the present study was to investigate in vivo the electrophysiological properties of LC and DRN neurons from WKY rats, using single-unit extracellular techniques. Wistar (Wis) and Sprague Dawley (SD) rats were used as control strains. In the LC from WKY rats the basal firing rate was higher than that obtained in the Wis and SD strain, and burst firing activity also was greater compared to that in Wis strain but not in SD. The sensitivity of LC neurons to the inhibitory effect of the α2-adrenoceptor agonist, clonidine and the antidepressant reboxetine was lower in WKY rats compared to Wis, but not SD. Regarding DRN neurons, in WKY rats burst activity was lower than that obtained in Wis and SD rats, although no differences were observed in other firing parameters. Interestingly, while the sensitivity of DRN neurons to the inhibitory effect of the 5-HT1A receptor agonist, 8-OH-DPAT was lower in the WKY strain, the antidepressant fluoxetine had a greater inhibitory potency in this rat strain compared to that recorded in the Wis group. Overall, these results point out important electrophysiological differences regarding noradrenergic and serotonergic systems between Wis and WKY rats, supporting the utility of the WKY rat as an important tool in the research of cellular basis of depression.
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Affiliation(s)
- C Bruzos-Cidón
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - C Miguelez
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain; Department of Pharmacology, School of Pharmacy, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - J J Rodríguez
- Department of Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, 48940 Leioa, Spain
| | - R Gutiérrez-Lanza
- Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, 48940 Leioa, Spain
| | - L Ugedo
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
| | - M Torrecilla
- Department of Pharmacology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
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Vasudeva RK, Waterhouse BD. Cellular profile of the dorsal raphe lateral wing sub-region: relationship to the lateral dorsal tegmental nucleus. J Chem Neuroanat 2014; 57-58:15-23. [PMID: 24704911 DOI: 10.1016/j.jchemneu.2014.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/25/2014] [Accepted: 03/04/2014] [Indexed: 01/09/2023]
Abstract
As one of the main serotonergic (5HT) projections to the forebrain, the dorsal raphe nucleus (DRN) has been implicated in disorders of anxiety and depression. Although the nucleus contains the densest population of 5HT neurons in the brain, at least 50% of cells within this structure are non-serotonergic, including a large population of nitric oxide synthase (NOS) containing neurons. The DRN has a unique topographical efferent organization and can also be divided into sub-regions based on rostro-caudal and medio-lateral dimensions. NOS is co-localized with 5HT in the midline DRN but NOS-positive cells in the lateral wing (LW) of the nucleus do not express 5HT. Interestingly, the NOS LW neuronal population is immediately rostral to and in line with the cholinergic lateral dorsal tegmental nucleus (LDT). We used immunohistochemical methods to investigate the potential serotonergic regulation of NOS LW neurons and also the association of this cell grouping to the LDT. Our results indicate that >75% of NOS LW neurons express the inhibitory 5HT1A receptor and are cholinergic (>90%). The findings suggest this assembly of cells is a rostral extension of the LDT, one that it is subject to regulation by 5HT release. As such the present study suggests a link between 5HT signaling, activation of cholinergic/NOS neurons, and the stress response including the pathophysiology underlying anxiety and depression.
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Affiliation(s)
- Rani K Vasudeva
- Temple University School of Medicine, Center for Substance Abuse Research, MERB 8th Floor, Philadelphia, PA 19140, United States; Drexel University College of Medicine, Department of Neurobiology & Anatomy, Queen Lane Campus, Philadelphia, PA 19129, United States.
| | - Barry D Waterhouse
- Drexel University College of Medicine, Department of Neurobiology & Anatomy, Queen Lane Campus, Philadelphia, PA 19129, United States.
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