1
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Codagnone MG, Kara N, Ratsika A, Levone BR, van de Wouw M, Tan LA, Cunningham JI, Sanchez C, Cryan JF, O'Leary OF. Inhibition of FKBP51 induces stress resilience and alters hippocampal neurogenesis. Mol Psychiatry 2022; 27:4928-4938. [PMID: 36104438 PMCID: PMC9763121 DOI: 10.1038/s41380-022-01755-9] [Citation(s) in RCA: 2] [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] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 07/07/2022] [Accepted: 08/15/2022] [Indexed: 01/19/2023]
Abstract
Stress-related psychiatric disorders such as depression are among the leading causes of morbidity and mortality. Considering that many individuals fail to respond to currently available antidepressant drugs, there is a need for antidepressants with novel mechanisms. Polymorphisms in the gene encoding FK506-binding protein 51 (FKBP51), a co-chaperone of the glucocorticoid receptor, have been linked to susceptibility to stress-related psychiatric disorders. Whether this protein can be targeted for their treatment remains largely unexplored. The aim of this work was to investigate whether inhibition of FKBP51 with SAFit2, a novel selective inhibitor, promotes hippocampal neuron outgrowth and neurogenesis in vitro and stress resilience in vivo in a mouse model of chronic psychosocial stress. Primary hippocampal neuronal cultures or hippocampal neural progenitor cells (NPCs) were treated with SAFit2 and neuronal differentiation and cell proliferation were analyzed. Male C57BL/6 mice were administered SAFit2 while concurrently undergoing a chronic stress paradigm comprising of intermittent social defeat and overcrowding, and anxiety and depressive -related behaviors were evaluated. SAFit2 increased neurite outgrowth and number of branch points to a greater extent than brain derived neurotrophic factor (BDNF) in primary hippocampal neuronal cultures. SAFit2 increased hippocampal NPC neurogenesis and increased neurite complexity and length of these differentiated neurons. In vivo, chronic SAFit2 administration prevented stress-induced social avoidance, decreased anxiety in the novelty-induced hypophagia test, and prevented stress-induced anxiety in the open field but did not alter adult hippocampal neurogenesis in stressed animals. These data warrant further exploration of inhibition of FKBP51 as a strategy to treat stress-related disorders.
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Affiliation(s)
- Martin G Codagnone
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Instituto de Biología Celular y Neurociencia "de Robertis" IBCN (UBA-CONICET), Buenos Aires, Argentina
| | - Nirit Kara
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Anna Ratsika
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Brunno Rocha Levone
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Marcel van de Wouw
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | | | | | | | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
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2
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Harris EP, Villalobos-Manriquez F, Melo TG, Clarke G, O'Leary OF. Stress during puberty exerts sex-specific effects on depressive-like behavior and monoamine neurotransmitters in adolescence and adulthood. Neurobiol Stress 2022; 21:100494. [DOI: 10.1016/j.ynstr.2022.100494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 11/15/2022] Open
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3
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Abstract
Gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the brain, acts at the ionotropic GABAA and GABAC receptors, and the metabotropic GABAB receptor. This chapter summarizes the studies that have investigated the role of the GABAB receptor in stress-related psychiatric disorders including anxiety and mood disorders. Overall, clinical and preclinical evidences strongly suggest that the GABAB receptor is a therapeutic candidate for depression and anxiety disorders. However, the clinical development of GABAB receptor-based drugs to treat these disorders has been hampered by their potential side-effects, particularly those of agonists. Nevertheless, the discovery of novel GABAB receptor allosteric modulators, and increasing understanding of the influence of specific intracellular GABAB receptor-associated proteins on GABAB receptor activity, may now pave the way towards GABAB receptor therapeutics in the treatment of mood and anxiety disorders.
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Affiliation(s)
- Daniela Felice
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
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4
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Nicolas S, McGovern AJ, Hueston CM, O'Mahony SM, Cryan JF, O'Leary OF, Nolan YM. Prior maternal separation stress alters the dendritic complexity of new hippocampal neurons and neuroinflammation in response to an inflammatory stressor in juvenile female rats. Brain Behav Immun 2022; 99:327-338. [PMID: 34732365 DOI: 10.1016/j.bbi.2021.10.016] [Citation(s) in RCA: 5] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 10/19/2021] [Accepted: 10/23/2021] [Indexed: 12/11/2022] Open
Abstract
Stress during critical periods of neurodevelopment is associated with an increased risk of developing stress-related psychiatric disorders, which are more common in women than men. Hippocampal neurogenesis (the birth of new neurons) is vulnerable to maternal separation (MS) and inflammatory stressors, and emerging evidence suggests that hippocampal neurogenesis is more sensitive to stress in the ventral hippocampus (vHi) than in the dorsal hippocampus (dHi). Although research into the effects of MS stress on hippocampal neurogenesis is well documented in male rodents, the effect in females remains underexplored. Similarly, reports on the impact of inflammatory stressors on hippocampal neurogenesis in females are limited, especially when female bias in the prevalence of stress-related psychiatric disorders begins to emerge. Thus, in this study we investigated the effects of MS followed by an inflammatory stressor (lipopolysaccharide, LPS) in early adolescence on peripheral and hippocampal inflammatory responses and hippocampal neurogenesis in juvenile female rats. We show that MS enhanced an LPS-induced increase in the pro-inflammatory cytokine IL-1β in the vHi but not in the dHi. However, microglial activation was similar following LPS alone or MS alone in both hippocampal regions, while MS prior to LPS reduced microglial activation in both dHi and vHi. The production of new neurons was unaffected by MS and LPS. MS and LPS independently reduced the dendritic complexity of new neurons, and MS exacerbated LPS-induced reductions in the complexity of distal dendrites of new neurons in the vHi but not dHi. These data highlight that MS differentially primes the physiological response to LPS in the juvenile female rat hippocampus.
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Affiliation(s)
- Sarah Nicolas
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Andrew J McGovern
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Cara M Hueston
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Siobhain M O'Mahony
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland.
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5
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Harris EP, McGovern AJ, Melo TG, Barron A, Nola YM, O'Leary OF. Juvenile Stress Exerts Sex-independent Effects on Anxiety, Antidepressant-like Behaviours and Dopaminergic Innervation of the Prelimbic Cortex in Adulthood and Does Not Alter Hippocampal Neurogenesis. Behav Brain Res 2021; 421:113725. [PMID: 34929235 DOI: 10.1016/j.bbr.2021.113725] [Citation(s) in RCA: 4] [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] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 11/24/2021] [Accepted: 12/15/2021] [Indexed: 11/26/2022]
Abstract
Stress, particularly during childhood, is a major risk factor for the development of depression. Depression is twice as prevalent in women compared to men, which suggests that that biological sex also contributes to depression susceptibility. However, the neurobiology underpinning sex differences in the long-term consequences of childhood stress remains unknown. Thus, the aim of this study was to determine whether stress applied during the prepubertal juvenile period (postnatal day 27-29) in rats induces sex-specific changes in anxiety-like behaviour, anhedonia, and antidepressant-like behaviour in adulthood in males and females. The impact of juvenile stress on two systems in the brain associated with these behaviours and that develop during the juvenile period, the mesocorticolimbic dopaminergic system and hippocampal neurogenesis, were also investigated. Juvenile stress altered escape-oriented behaviours in the forced swim test in both sexes, decreased latency to drink a palatable substance in a novel environment in the novelty-induced hypophagia test in both sexes, and decreased open field supported rearing behavior in females. These behavioural changes were accompanied by stress-induced increases in tyrosine hydroxylase immunoreactivity in the prefrontal cortex of both sexes, but not other regions of the mesocorticolimbic dopaminergic system. Juvenile stress did not impact anhedonia in adulthood as measured by the saccharin preference test and had no effect hippocampal neurogenesis across the longitudinal axis of the hippocampus. These results suggest that juvenile stress has long-lasting impacts on antidepressant-like and reward-seeking behaviour in adulthood and these changes may be due to alterations to catecholaminergic innervation of the medial prefrontal cortex.
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Affiliation(s)
- Erin P Harris
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Andrew J McGovern
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Thieza G Melo
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Aaron Barron
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Yvonne M Nola
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland.
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6
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Levone BR, Cryan JF, O'Leary OF. Specific sub-regions of the longitudinal axis of the hippocampus mediate behavioural responses to chronic psychosocial stress. Neuropharmacology 2021; 201:108843. [PMID: 34666075 DOI: 10.1016/j.neuropharm.2021.108843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/14/2021] [Accepted: 10/14/2021] [Indexed: 12/29/2022]
Abstract
Accumulating evidence suggests that the hippocampus is functionally segregated along its longitudinal axis into a dorsal (dHi) sub-region, shown to play roles in learning & memory and a ventral sub-region (vHi), involved in anxiety and antidepressant action. Recent studies also suggest that the intermediate hippocampus (iHi) might be functionally independent, but it has received relatively little attention. We recently found that the iHi is involved in the behavioural effects of chronic treatment with the antidepressant fluoxetine in the forced swim test. However, the roles of specific sub-regions of the longitudinal axis of the hippocampus in the response to chronic stress, a risk factor for depression and anxiety disorders, has not yet been investigated. Therefore, we used excitotoxic lesions of the dHi, iHi or vHi in male C57BL/6 mice to investigate the roles of these sub-regions in the behavioural (anxiety, anhedonia, depression) responses to chronic psychosocial stress. We found that stress-induced increases in anxiety in the novelty-induced hypophagia and marble burying tests were prevented by each of the sub-region lesions, but only vHi lesions attenuated stress-induced anxiety in the open field test. Stress-induced anhedonia was reduced in dHi- and vHi- but not iHi-lesioned mice. In stressed mice, only vHi lesions induced an antidepressant-like effect in the forced swim test and prolonged latency to adopt a defeat posture during social defeat, suggesting an increase in stress resilience. Interestingly, iHi lesions increased stress-induced social avoidance in the social interaction test. In summary, we found that all hippocampal sub-regions are involved in the anxiogenic effects of chronic stress but that the iHi plays a predominant role in stress-induced social avoidance and the vHi has a predominant role in active coping behaviours and antidepressant-like behaviour following chronic stress.
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Affiliation(s)
- Brunno Rocha Levone
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland.
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7
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Boehme M, Guzzetta KE, Bastiaanssen TFS, van de Wouw M, Moloney GM, Gual-Grau A, Spichak S, Olavarría-Ramírez L, Fitzgerald P, Morillas E, Ritz NL, Jaggar M, Cowan CSM, Crispie F, Donoso F, Halitzki E, Neto MC, Sichetti M, Golubeva AV, Fitzgerald RS, Claesson MJ, Cotter PD, O'Leary OF, Dinan TG, Cryan JF. Microbiota from young mice counteracts selective age-associated behavioral deficits. Nat Aging 2021; 1:666-676. [PMID: 37117767 DOI: 10.1038/s43587-021-00093-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 06/25/2021] [Indexed: 04/30/2023]
Abstract
The gut microbiota is increasingly recognized as an important regulator of host immunity and brain health. The aging process yields dramatic alterations in the microbiota, which is linked to poorer health and frailty in elderly populations. However, there is limited evidence for a mechanistic role of the gut microbiota in brain health and neuroimmunity during aging processes. Therefore, we conducted fecal microbiota transplantation from either young (3-4 months) or old (19-20 months) donor mice into aged recipient mice (19-20 months). Transplant of a microbiota from young donors reversed aging-associated differences in peripheral and brain immunity, as well as the hippocampal metabolome and transcriptome of aging recipient mice. Finally, the young donor-derived microbiota attenuated selective age-associated impairments in cognitive behavior when transplanted into an aged host. Our results reveal that the microbiome may be a suitable therapeutic target to promote healthy aging.
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Affiliation(s)
- Marcus Boehme
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Katherine E Guzzetta
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Thomaz F S Bastiaanssen
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Gerard M Moloney
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Simon Spichak
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | | | | | - Nathaniel L Ritz
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Minal Jaggar
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | | | - Fiona Crispie
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
| | - Francisco Donoso
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - Evelyn Halitzki
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Marta C Neto
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Marzia Sichetti
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Anna V Golubeva
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Rachel S Fitzgerald
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Marcus J Claesson
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- School of Microbiology, University College Cork, Cork, Ireland
| | - Paul D Cotter
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
| | - Olivia F O'Leary
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Timothy G Dinan
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F Cryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland.
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
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8
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Levone BR, Moloney GM, Cryan JF, O'Leary OF. Specific sub-regions along the longitudinal axis of the hippocampus mediate antidepressant-like behavioral effects. Neurobiol Stress 2021; 14:100331. [PMID: 33997156 PMCID: PMC8100619 DOI: 10.1016/j.ynstr.2021.100331] [Citation(s) in RCA: 4] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/02/2021] [Accepted: 04/17/2021] [Indexed: 01/15/2023] Open
Abstract
Current antidepressants are suboptimal due incomplete understanding of the neurobiology underlying their behavioral effects. However, imaging studies suggest the hippocampus is a key brain region underpinning antidepressant action. There is increasing attention on the functional segregation of the hippocampus into a dorsal region (dHi) predominantly involved in spatial learning and memory, and a ventral region (vHi) which regulates anxiety, a symptom often co-morbid with depression. However, little is known about the roles of these hippocampal sub-regions in the antidepressant response. Moreover, the area between them, the intermediate hippocampus (iHi), has received little attention. Here, we investigated the impact of dHi, iHi or vHi lesions on anxiety- and depressive-like behaviors under baseline or antidepressant treatment conditions in male C57BL/6 mice (n = 8-10). We found that in the absence of fluoxetine, vHi lesions reduced anxiety-like behavior, while none of the lesions affected other antidepressant-sensitive behaviors. vHi lesions prevented the acute antidepressant-like behavioral effects of fluoxetine in the tail suspension test and its anxiolytic effects in the novelty-induced hypophagia test. Intriguingly, only iHi lesions prevented the antidepressant effects of chronic fluoxetine treatment in the forced swim test. dHi lesions did not impact any behaviors either in the absence or presence of fluoxetine. In summary, we found that vHi plays a key role in anxiety-like behavior and its modulation by fluoxetine, while both iHi and vHi play distinct roles in fluoxetine-induced antidepressant-like behaviors.
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Affiliation(s)
- Brunno Rocha Levone
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Gerard M Moloney
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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9
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Pawley LC, Hueston CM, O'Leary JD, Kozareva DA, Cryan JF, O'Leary OF, Nolan YM. Chronic intrahippocampal interleukin-1β overexpression in adolescence impairs hippocampal neurogenesis but not neurogenesis-associated cognition. Brain Behav Immun 2020; 83:172-179. [PMID: 31604142 DOI: 10.1016/j.bbi.2019.10.007] [Citation(s) in RCA: 16] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/02/2019] [Accepted: 10/05/2019] [Indexed: 02/06/2023] Open
Abstract
Both neuroinflammation and adult hippocampal neurogenesis (AHN) are implicated in many neurodegenerative disorders as well as in neuropsychiatric disorders, which often become symptomatic during adolescence. A better knowledge of the impact that chronic neuroinflammation has on the hippocampus during the adolescent period could lead to the discovery of new therapeutics for some of these disorders. The hippocampus is particularly vulnerable to altered concentrations of the pro-inflammatory cytokine interleukin-1β (IL-1β), with elevated levels implicated in the aetiology of neurodegenerative disorders such as Alzheimer's and Parkinson's, and stress-related disorders such as depression. The effect of acutely and chronically elevated concentrations of hippocampal IL-1β have been shown to reduce AHN in adult rodents. However, the effect of exposure to chronic overexpression of hippocampal IL-1β during adolescence, a time of increased vulnerability, hasn't been fully interrogated. Thus, in this study we utilized a lentiviral approach to induce chronic overexpression of IL-1β in the dorsal hippocampus of adolescent male Sprague Dawley rats for 5 weeks, during which time its impact on cognition and hippocampal neurogenesis were examined. A reduction in hippocampal neurogenesis was observed along with a reduced level of neurite branching on hippocampal neurons. However, there was no effect of IL-1β overexpression on performance in pattern separation, novel object recognition or spontaneous alternation in the Y maze. Our study has highlighted that chronic IL-1β overexpression in the hippocampus during the adolescent period exerts a negative impact on neurogenesis independent of cognitive performance, and suggests a degree of resilience of the adolescent hippocampus to inflammatory insult.
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Affiliation(s)
- Lauren C Pawley
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Cara M Hueston
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - James D O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Danka A Kozareva
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland.
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10
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O'Donovan SM, Crowley EK, Brown JRM, O'Sullivan O, O'Leary OF, Timmons S, Nolan YM, Clarke DJ, Hyland NP, Joyce SA, Sullivan AM, O'Neill C. Nigral overexpression of α-synuclein in a rat Parkinson's disease model indicates alterations in the enteric nervous system and the gut microbiome. Neurogastroenterol Motil 2020; 32:e13726. [PMID: 31576631 DOI: 10.1111/nmo.13726] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [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: 04/20/2019] [Revised: 09/02/2019] [Accepted: 09/02/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND A hallmark feature of Parkinson's disease (PD) is the build-up of α-synuclein protein aggregates throughout the brain; however α-synuclein is also expressed in enteric neurons. Gastrointestinal (GI) symptoms and pathology are frequently reported in PD, including constipation, increased intestinal permeability, glial pathology, and alterations to gut microbiota composition. α-synuclein can propagate through neuronal systems but the site of origin of α-synuclein pathology, whether it be the gut or the brain, is still unknown. Physical exercise is associated with alleviating symptoms of PD and with altering the composition of the gut microbiota. METHODS This study investigated the effects of bilateral nigral injection of adeno-associated virus (AAV)-α-synuclein on enteric neurons, glia and neurochemistry, the gut microbiome, and bile acid metabolism in rats, some of whom were exposed to voluntary exercise. KEY RESULTS Nigral overexpression of α-synuclein resulted in significant neuronal loss in the ileal submucosal plexus with no change in enteric glia. In contrast, the myenteric plexus showed a significant increase in glial expression, while neuronal numbers were maintained. Concomitant alterations were observed in the gut microbiome and related bile acid metabolism. Voluntary running protected against neuronal loss, increased enteric glial expression, and modified gut microbiome composition in the brain-injected AAV-α-synuclein PD model. CONCLUSIONS AND INFERENCES These results show that developing nigral α-synuclein pathology in this PD model exerts significant alterations on the enteric nervous system (ENS) and gut microbiome that are receptive to modification by exercise. This highlights brain to gut communication as an important mechanism in PD pathology.
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Affiliation(s)
- Sarah M O'Donovan
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland
| | - Erin K Crowley
- Cork Neuroscience Centre, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Orla O'Sullivan
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Teagasc Food Research Centre Moorepark, Cork, Ireland
| | - Olivia F O'Leary
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Suzanne Timmons
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland.,Centre of Gerontology and Rehabilitation, University College Cork, Cork, Ireland
| | - Yvonne M Nolan
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - David J Clarke
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
| | - Niall P Hyland
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Department of Physiology, University College Cork, Cork, Ireland
| | - Susan A Joyce
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Aideen M Sullivan
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Cora O'Neill
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.,Cork Neuroscience Centre, University College Cork, Cork, Ireland
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11
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Abstract
Depression remains one of the most prevalent psychiatric disorders, with many patients not responding adequately to available treatments. Chronic or early-life stress is one of the key risk factors for depression. In addition, a growing body of data implicates chronic inflammation as a major player in depression pathogenesis. More recently, the gut microbiota has emerged as an important regulator of brain and behavior and also has been linked to depression. However, how this holy trinity of risk factors interact to maintain physiological homeostasis in the brain and body is not fully understood. In this review, we integrate the available data from animal and human studies on these three factors in the etiology and progression of depression. We also focus on the processes by which this microbiota-immune-stress matrix may influence centrally mediated events and on possible therapeutic interventions to correct imbalances in this triune.
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Affiliation(s)
- Joana S Cruz-Pereira
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , , .,Department of Anatomy and Neuroscience, University College Cork, Cork T12 K8AF, Ireland
| | - Kieran Rea
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , ,
| | - Yvonne M Nolan
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , , .,Department of Anatomy and Neuroscience, University College Cork, Cork T12 K8AF, Ireland
| | - Olivia F O'Leary
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , , .,Department of Anatomy and Neuroscience, University College Cork, Cork T12 K8AF, Ireland
| | - Timothy G Dinan
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , , .,Department of Psychiatry and Neurobehavioral Science, University College Cork, Cork T12 K8AF, Ireland
| | - John F Cryan
- APC Microbiome Ireland, University College Cork, Cork T12 K8AF, Ireland; , , , , , .,Department of Anatomy and Neuroscience, University College Cork, Cork T12 K8AF, Ireland
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12
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Ramos Costa AP, Levone BR, Gururajan A, Moloney G, Hoeller AA, Lino-de-Oliveira C, Dinan TG, O'Leary OF, Monteiro de Lima TC, Cryan JF. Enduring effects of muscarinic receptor activation on adult hippocampal neurogenesis, microRNA expression and behaviour. Behav Brain Res 2019; 362:188-198. [PMID: 30650342 DOI: 10.1016/j.bbr.2018.12.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [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: 09/25/2018] [Revised: 12/17/2018] [Accepted: 12/22/2018] [Indexed: 12/27/2022]
Abstract
The cholinergic system is one of the most important neurotransmitter systems in the brain with key roles in autonomic control and the regulation of cognitive and emotional responses. However, the precise mechanism by which the cholinergic system influences behaviour is unclear. Adult hippocampal neurogenesis (AHN) is a potential mediator in this context based on evidence, which has identified this process as putative mechanism of antidepressant action. More recently, post-transcriptional regulation by microRNAs is another candidate mechanism based on its involvement in the regulation of AHN and neurotransmission. Taking into account this background, we evaluated the behavioural effects of a non-convulsant dose of pilocarpine - a non-selective muscarinic receptor (mAChR) agonist - in adult Wistar rats. Furthermore, we quantified the expression of different microRNAs implicated in the regulation of AHN. Our results suggests that pilocarpine treatment increases AHN in the granular cell layer but also induced ectopic neurogenesis. Pilocarpine treatment reduced immobility time in forced swimming test but did not affect fear conditioning response, sucrose preference or novelty supressed feeding behaviour. In addition, treatment with pilocarpine down-regulated the expression of 6 microRNAs implicated in the regulation of neurotrophin signalling and axon guidance pathways. Therefore, we suggest that the low-dose stimulation of the cholinergic system is sufficient to alter AHN of rats through post-transcriptional mechanisms, which might contribute to long-lasting behavioural effects.
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Affiliation(s)
- Ana Paula Ramos Costa
- APC Microbiome Ireland, University College Cork, Ireland; Graduate Program in Medical Sciences, Federal University of Santa Catarina, Brazil
| | | | - Anand Gururajan
- APC Microbiome Ireland, University College Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Gerard Moloney
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Alexandre A Hoeller
- Graduate Program in Medical Sciences, Federal University of Santa Catarina, Brazil
| | | | | | - Olivia F O'Leary
- APC Microbiome Ireland, University College Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Ireland
| | | | - John F Cryan
- APC Microbiome Ireland, University College Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Ireland.
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13
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Codagnone MG, Spichak S, O'Mahony SM, O'Leary OF, Clarke G, Stanton C, Dinan TG, Cryan JF. Programming Bugs: Microbiota and the Developmental Origins of Brain Health and Disease. Biol Psychiatry 2019; 85:150-163. [PMID: 30064690 DOI: 10.1016/j.biopsych.2018.06.014] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [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: 03/15/2018] [Revised: 05/29/2018] [Accepted: 06/18/2018] [Indexed: 02/06/2023]
Abstract
It has been nearly 30 years since Dr. David Barker first highlighted the importance of prenatal factors in contributing to the developmental origins of adult disease. This concept was later broadened to include postnatal events. It is clear that the interaction between genetic predisposition and early life environmental exposures is key in this regard. However, recent research has also identified another important factor in the microbiota-the trillions of microorganisms that inhabit key body niches, including the vagina and gastrointestinal tract. Because the composition of these maternal microbiome sites has been linked to maternal metabolism and is also vertically transmitted to offspring, changes in the maternal microbiota are poised to significantly affect the newborn. In fact, several lines of evidence show that the gut microbiota interacts with diet, drugs, and stress both prenatally and postnatally and that these exogenous factors could also affect the dynamic changes in the microbiota composition occurring during pregnancy. Animal models have shown great utility in illuminating how these disruptions result in behavioral and brain morphological phenotypes reminiscent of psychiatric disorders (anxiety, depression, schizophrenia, and autism spectrum disorders). Increasing evidence points to critical interactions among the microbiota, host genetics, and both the prenatal and postnatal environments to temporally program susceptibility to psychiatric disorders later in life. Sex-specific phenotypes may be programmed through the influence of the microbiota on the hypothalamic-pituitary-adrenal axis and neuroimmune system.
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Affiliation(s)
- Martin G Codagnone
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Simon Spichak
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Siobhain M O'Mahony
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Olivia F O'Leary
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Gerard Clarke
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland; Irish Centre for Fetal and Neonatal Translational Research and Cork University Maternity Hospital, University College Cork, Cork, Ireland
| | - Catherine Stanton
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Irish Centre for Fetal and Neonatal Translational Research and Cork University Maternity Hospital, University College Cork, Cork, Ireland; Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
| | - Timothy G Dinan
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F Cryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
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14
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O'Leary JD, Hoban AE, Murphy A, O'Leary OF, Cryan JF, Nolan YM. Differential effects of adolescent and adult-initiated exercise on cognition and hippocampal neurogenesis. Hippocampus 2018; 29:352-365. [PMID: 30844139 DOI: 10.1002/hipo.23032] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/14/2018] [Accepted: 09/13/2018] [Indexed: 12/12/2022]
Abstract
Adolescence is a critical period for postnatal brain maturation and thus a time when environmental influences may affect cognitive processes in later life. Exercise during adulthood has been shown to increase hippocampal neurogenesis and enhance cognition. However, the impact of exercise initiated in adolescence on the brain and behavior in adulthood is not fully understood. The aim of this study was to compare the impact of voluntary exercise that is initiated during adolescence or early adulthood on cognitive performance in hippocampal-dependent and -independent processes using both object-based and touchscreen operant paradigms. Adult (8 week) and adolescent (4 week) male Sprague-Dawley rats had access to a running wheel (exercise) or were left undisturbed (sedentary control) for 4 weeks prior to behavioral testing and for the duration of the experiment. Results from touchscreen-based tasks showed that reversal learning was enhanced by both adult and adolescent-initiated exercise, while only exercise that began in adolescence induced a subtle but transient increase in performance on a location discrimination task. Spontaneous alternation in the Y-maze was impaired following adolescent onset exercise, while object memory was unaffected by either adult or adolescent-initiated exercise. Adolescent-initiated exercise increased the number of hippocampal DCX cells, an indicator of neurogenesis. It also promoted the complexity of neurites on DCX cells, a key process for synaptic integration, to a greater degree than adult-initiated exercise. Together the data here show that exercise during the adolescent period compared to adulthood differentially affects cognitive processes and the development of new hippocampal neurons in later life.
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Affiliation(s)
- James D O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Alan E Hoban
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Ashley Murphy
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
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15
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Hueston CM, O'Leary JD, Hoban AE, Kozareva DA, Pawley LC, O'Leary OF, Cryan JF, Nolan YM. Chronic interleukin-1β in the dorsal hippocampus impairs behavioural pattern separation. Brain Behav Immun 2018; 74:252-264. [PMID: 30217534 DOI: 10.1016/j.bbi.2018.09.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [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: 06/21/2018] [Revised: 08/31/2018] [Accepted: 09/10/2018] [Indexed: 02/04/2023] Open
Abstract
Understanding the long-term consequences of chronic inflammation in the hippocampus may help to develop therapeutic targets for the treatment of cognitive disorders related to stress, ageing and neurodegeneration. The hippocampus is particularly vulnerable to increases in the pro-inflammatory cytokine interleukin-1β (IL-1β), a mediator of neuroinflammation, with elevated levels implicated in the aetiology of neurodegenerative diseases such as Alzheimer's and Parkinson's, and in stress-related disorders such as depression. Acute increases in hippocampal IL-1β have been shown to impair cognition and reduce adult hippocampal neurogenesis, the birth of new neurons. However, the impact of prolonged increases in IL-1β, as evident in clinical conditions, on cognition has not been fully explored. Therefore, the present study utilized a lentiviral approach to induce long-term overexpression of IL-1β in the dorsal hippocampus of adult male Sprague Dawley rats and examine its impact on cognition. Following three weeks of viral integration, pattern separation, a process involving hippocampal neurogenesis, was impaired in IL-1β-treated rats in both object-location and touchscreen operant paradigms. This was coupled with a decrease in the number and neurite complexity of immature neurons in the hippocampus. Conversely, tasks involving the hippocampus, but not sensitive to disruption of hippocampal neurogenesis, including spontaneous alternation, novel object and location recognition were unaffected. Touchscreen operant visual discrimination, a cognitive task involving the prefrontal cortex, was largely unaffected by IL-1β overexpression. In conclusion, these findings suggest that chronically elevated IL-1β in the hippocampus selectively impairs pattern separation. Inflammatory-mediated disruption of adult hippocampal neurogenesis may contribute to the cognitive decline associated with neurodegenerative and stress-related disorders.
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Affiliation(s)
- Cara M Hueston
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - James D O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Alan E Hoban
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Danka A Kozareva
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Lauren C Pawley
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland.
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16
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O'Leary JD, Hoban AE, Cryan JF, O'Leary OF, Nolan YM. Differential effects of adolescent and adult-initiated voluntary exercise on context and cued fear conditioning. Neuropharmacology 2018; 145:49-58. [PMID: 29793890 DOI: 10.1016/j.neuropharm.2018.05.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [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: 12/03/2017] [Revised: 04/19/2018] [Accepted: 05/06/2018] [Indexed: 12/20/2022]
Abstract
Adolescence is a critical period for postnatal brain maturation and a time during which there is increased susceptibility to developing emotional and cognitive-related disorders. Exercise during adulthood has been shown to increase hippocampal plasticity and enhance cognition. However, the impact of exercise initiated in adolescence, on brain and behaviour in adulthood is not yet fully explored or understood. The aim of this study was to compare the impact of voluntary exercise that was initiated either during adolescence or early adulthood on cognitive performance in hippocampal and amygdala-dependent fear conditioning tasks in adulthood. Adult (eight weeks old) and adolescent (four weeks old) male Sprague Dawley rats had access to a running wheel (exercise) or were left undisturbed (sedentary control) for seven weeks. Adult-initiated exercise enhanced both contextual and cued fear conditioning, while conversely, exercise that began in adolescence did not affect performance in these tasks. These behaviours were accompanied by differential expression of plasticity-related genes in the hippocampus and amygdala in adulthood. Specifically, adolescent-initiated exercise increased the expression of an array of plasticity related genes in the hippocampus including BDNF, synaptophysin, Creb, PSD-95, Arc, TLX and DCX, while adult-initiated exercise did not affect hippocampal plasticity related genes. Together results show that exercise initiated during adolescence has a differential effect on hippocampal and amygdala-dependent behaviour and neuronal plasticity compared to when exercise was initiated in adulthood. These findings reinforce adolescence as a period during which environmental influences have a distinct impact on neuronal plasticity and cognition. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".
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Affiliation(s)
- James D O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - Alan E Hoban
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Ireland, University College Cork, Ireland.
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17
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Kozareva DA, O'Leary OF, Cryan JF, Nolan YM. Cover Image, Volume 28, Issue 1. Hippocampus 2017. [DOI: 10.1002/hipo.22770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Danka A. Kozareva
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - Olivia F. O'Leary
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - John F. Cryan
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - Yvonne M. Nolan
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
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18
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Kozareva DA, O'Leary OF, Cryan JF, Nolan YM. Deletion of TLX and social isolation impairs exercise-induced neurogenesis in the adolescent hippocampus. Hippocampus 2017; 28:3-11. [DOI: 10.1002/hipo.22805] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 09/07/2017] [Accepted: 09/20/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Danka A. Kozareva
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - Olivia F. O'Leary
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - John F. Cryan
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
| | - Yvonne M. Nolan
- Department of Anatomy and Neuroscience; University College Cork; Ireland
- APC Microbiome Institute; University College Cork; Ireland
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19
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Moloney GM, O'Leary OF, Salvo-Romero E, Desbonnet L, Shanahan F, Dinan TG, Clarke G, Cryan JF. Microbial regulation of hippocampal miRNA expression: Implications for transcription of kynurenine pathway enzymes. Behav Brain Res 2017; 334:50-54. [PMID: 28736331 DOI: 10.1016/j.bbr.2017.07.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 01/15/2023]
Abstract
Increasing evidence points to a functional role of the enteric microbiota in brain development, function and behaviour including the regulation of transcriptional activity in the hippocampus. Changes in CNS miRNA expression may reflect the colonisation status of the gut. Given the pivotal impact of miRNAs on gene expression, our study was based on the hypothesis that gene expression would also be altered in the germ-free state in the hippocampus. We measured miRNAs in the hippocampus of Germ free (GF), conventional (C) and Germ free colonised (exGF) Swiss Webster mice. miRNAs were selected for follow up based on significant differences in expression between groups according to sex and colonisation status. The expression of miR-294-5p was increased in male germ free animals and was normalised following colonisation. Targets of the differentially expressed miRNAs were over-represented in the kynurenine pathway. We show that the microbiota modulates the expression of miRNAs associated with kynurenine pathway metabolism and, demonstrate that the gut microbiota regulates the expression of kynurenine pathway genes in the hippocampus. We also show a sex-specific role for the microbiota in the regulation of miR-294-5p expression in the hippocampus. The gut microbiota plays an important role in modulating small RNAs that influence hippocampal gene expression, a process critical to hippocampal development.
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Affiliation(s)
- Gerard M Moloney
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
| | - Eloisa Salvo-Romero
- Laboratory of Neuro-Immuno-Gastroenterology, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca, Department of Gastroenterology, Hospital Universitario Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Lieve Desbonnet
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
| | - Fergus Shanahan
- APC Microbiome Institute, University College Cork, Cork, Ireland.
| | - Timothy G Dinan
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
| | - Gerard Clarke
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
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20
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Cussotto S, Cryan JF, O'Leary OF. The hippocampus and dorsal raphe nucleus are key brain areas associated with the antidepressant effects of lithium augmentation of desipramine. Neurosci Lett 2017; 648:14-20. [PMID: 28351776 DOI: 10.1016/j.neulet.2017.03.040] [Citation(s) in RCA: 3] [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] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 02/09/2017] [Accepted: 03/23/2017] [Indexed: 11/25/2022]
Abstract
Approximately 50% of depressed individuals fail to achieve remission with first-line antidepressant drugs and a third remain treatment-resistant. When first-line antidepressant treatment is unsuccessful, second-line strategies include dose optimisation, switching to another antidepressant, combination with another antidepressant, or augmentation with a non-antidepressant medication. Much of the evidence for the efficacy of augmentation strategies comes from studies using lithium to augment the effects of tricyclic antidepressants. The neural circuitry underlying the therapeutic effects of lithium augmentation is not yet fully understood. Recently, we reported that chronic treatment with a combination of lithium and the antidepressant desipramine, exerted antidepressant-like behavioural effects in a mouse strain (BALB/cOLaHsd) that did not exhibit an antidepressant-like behavioural response to either drug alone. In the present study, we used this model in combination with ΔFosB/FosB immunohistochemistry to identify brain regions chronically affected by lithium augmentation of desipramine when compared to either treatment alone. The data suggest that the dorsal raphe nucleus and the CA3 regions of the dorsal hippocampus are key nodes in the neural circuitry underlying antidepressant action of lithium augmentation of desipramine. These data give new insight into the neurobiology underlying the mechanism of lithium augmentation in the context of treatment-resistant depression.
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Affiliation(s)
- Sofia Cussotto
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland.
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21
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O'Leary JD, O'Leary OF, Cryan JF, Nolan YM. Regulation of behaviour by the nuclear receptor TLX. Genes Brain Behav 2016; 17:e12357. [PMID: 27790850 DOI: 10.1111/gbb.12357] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 09/15/2016] [Accepted: 10/25/2016] [Indexed: 01/10/2023]
Abstract
The orphan nuclear receptor Tlx (Nr2e1) is a key regulator of both embryonic and adult hippocampal neurogenesis. Several different mouse models have been developed which target Tlx in vivo including spontaneous deletion models (from birth) and targeted and conditional knockouts. Although some conflicting findings have been reported, for the most part studies have demonstrated that Tlx is important in regulating processes that underlie neurogenesis, spatial learning, anxiety-like behaviour and interestingly, aggression. More recent data have demonstrated that disrupting Tlx during early life induces hyperactivity and that Tlx plays a role in emotional regulation. Moreover, there are sex- and age-related differences in some behaviours in Tlx knockout mice during adolescence and adulthood. Here, we discuss the role of Tlx in motor-, cognitive-, aggressive- and anxiety-related behaviours during adolescence and adulthood. We examine current evidence which provides insight into Tlx during neurodevelopment, and offer our thoughts on the function of Tlx in brain and behaviour. We further hypothesize that Tlx is a key target in understanding the emergence of neurobiological disorders during adolescence and early adulthood.
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Affiliation(s)
- J D O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - O F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Institute, University College Cork, Cork, Ireland
| | - J F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Institute, University College Cork, Cork, Ireland
| | - Y M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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22
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Crowley T, Cryan JF, Downer EJ, O'Leary OF. Inhibiting neuroinflammation: The role and therapeutic potential of GABA in neuro-immune interactions. Brain Behav Immun 2016; 54:260-277. [PMID: 26851553 DOI: 10.1016/j.bbi.2016.02.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [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: 10/29/2015] [Revised: 01/22/2016] [Accepted: 02/02/2016] [Indexed: 12/25/2022] Open
Abstract
The central nervous system, once thought to be a site of immunological privilege, has since been found to harbour immunocompetent cells and to communicate with the peripheral nervous system. In the central nervous system (CNS), glial cells display immunological responses to pathological and physiological stimuli through pro- and anti-inflammatory cytokine and chemokine signalling, antigen presentation and the clearing of cellular debris through phagocytosis. While this neuroinflammatory signalling can act to reduce neuronal damage and comprises a key facet of CNS homeostasis, persistent inflammation or auto-antigen-mediated immunoreactivity can induce a positive feedback cycle of neuroinflammation that ultimately results in necrosis of glia and neurons. Persistent neuroinflammation has been recognised as a major pathological component of virtually all neurodegenerative diseases and has also been a focus of research into the pathology underlying psychiatric disorders. Thus, pharmacological strategies to curb the pathological effects of persistent neuroinflammation are of interest for many disorders of the CNS. Accumulating evidence suggests that GABAergic activities are closely bound to immune processes and signals, and thus the GABAergic neurotransmitter system might represent an important therapeutic target in modulating neuroinflammation. Here, we review evidence that inflammation induces changes in the GABA neurotransmitter system in the CNS and that GABAergic signalling exerts a reciprocal influence over neuroinflammatory processes. Together, the data support the hypothesis that the GABA system is a potential therapeutic target in the modulation of central inflammation.
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Affiliation(s)
- Tadhg Crowley
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland
| | - Eric J Downer
- School of Medicine, Discipline of Physiology, Trinity Biomedical Sciences Institute, Trinity College, Dublin 2, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland.
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23
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Ogbonnaya ES, Clarke G, Shanahan F, Dinan TG, Cryan JF, O'Leary OF. Adult Hippocampal Neurogenesis Is Regulated by the Microbiome. Biol Psychiatry 2015; 78:e7-9. [PMID: 25700599 DOI: 10.1016/j.biopsych.2014.12.023] [Citation(s) in RCA: 293] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 12/30/2014] [Indexed: 12/19/2022]
Affiliation(s)
- Ebere S Ogbonnaya
- Departments of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Gerard Clarke
- Departments of Psychiatry, University College Cork, Cork, Ireland; Departments of Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - Fergus Shanahan
- Departments of Medicine, University College Cork, Cork, Ireland; Departments of Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - Timothy G Dinan
- Departments of Psychiatry, University College Cork, Cork, Ireland; Departments of Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
| | - John F Cryan
- Departments of Anatomy and Neuroscience, University College Cork, Cork, Ireland; Departments of Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Departments of Anatomy and Neuroscience, University College Cork, Cork, Ireland; Departments of Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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Crowley T, Fitzpatrick JM, Kuijper T, Cryan JF, O'Toole O, O'Leary OF, Downer EJ. Modulation of TLR3/TLR4 inflammatory signaling by the GABAB receptor agonist baclofen in glia and immune cells: relevance to therapeutic effects in multiple sclerosis. Front Cell Neurosci 2015; 9:284. [PMID: 26283920 PMCID: PMC4516894 DOI: 10.3389/fncel.2015.00284] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [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: 05/14/2015] [Accepted: 07/10/2015] [Indexed: 12/11/2022] Open
Abstract
The GABAB receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in a number of disorders including multiple sclerosis (MS), but its precise mechanism of action is unknown. Neuroinflammation drives the central pathology in MS and is mediated by both immunoreactive glial cells and invading lymphocytes. Furthermore, a body of data indicates that the Toll-like receptor (TLR) family of innate immune receptors is implicated in MS progression. In the present study we investigated whether modulation of GABAB receptors using baclofen can exert anti-inflammatory effects by targeting TLR3 and(or) TLR4-induced inflammatory signaling in murine glial cells and human peripheral blood mononuclear cells (PBMCs) isolated from healthy control individuals and patients with the relapse-remitting (RR) form of MS. TLR3 and TLR4 stimulation promoted the nuclear sequestration of NF-κB and pro-inflammatory cytokine expression in murine glia, while TLR4, but not TLR3, promoted pro-inflammatory cytokine expression in PBMCs isolated from both healthy donors and RR-MS patients. Importantly, this effect was exacerbated in RR-MS patient immune cells. We present further evidence that baclofen dose-dependently attenuated TLR3- and TLR4-induced inflammatory signaling in primary glial cells. Pre-exposure of PBMCs isolated from healthy donors to baclofen attenuated TLR4-induced TNF-α expression, but did not affect TLR4-induced TNF-α expression in RR-MS patient PBMCs. Interestingly, mRNA expression of the GABAB receptor was reduced in PBMCs from RR-MS donors when compared to healthy controls, an effect that might contribute to the differential sensitivity to baclofen seen in healthy and RR-MS patient cells. Overall these findings indicate that baclofen differentially regulates TLR3 and TLR4 signaling in glia and immune cells, and offers insight on the role of baclofen in the treatment of neuroinflammatory disease states including MS.
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Affiliation(s)
- Tadhg Crowley
- Department of Anatomy and Neuroscience, University College Cork Cork, Ireland
| | | | - Teun Kuijper
- Department of Anatomy and Neuroscience, University College Cork Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork Cork, Ireland ; Alimentary Pharmabiotic Centre, University College Cork Cork, Ireland
| | | | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork Cork, Ireland ; Alimentary Pharmabiotic Centre, University College Cork Cork, Ireland
| | - Eric J Downer
- Department of Anatomy and Neuroscience, University College Cork Cork, Ireland ; School of Medicine, Discipline of Physiology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland
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Levone BR, Cryan JF, O'Leary OF. Role of adult hippocampal neurogenesis in stress resilience. Neurobiol Stress 2014; 1:147-55. [PMID: 27589664 PMCID: PMC4721321 DOI: 10.1016/j.ynstr.2014.11.003] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [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: 08/20/2014] [Revised: 10/30/2014] [Accepted: 11/03/2014] [Indexed: 02/04/2023] Open
Abstract
There is a growing appreciation that adult hippocampal neurogenesis plays a role in emotional and cognitive processes related to psychiatric disorders. Although many studies have investigated the effects of stress on adult hippocampal neurogenesis, most have not focused on whether stress-induced changes in neurogenesis occur specifically in animals that are more resilient or more susceptible to the behavioural and neuroendocrine effects of stress. Thus, in the present review we explore whether there is a clear relationship between stress-induced changes in adult hippocampal neurogenesis, stress resilience and antidepressant-induced recovery from stress-induced changes in behaviour. Exposure to different stressors is known to reduce adult hippocampal neurogenesis, but some stressors have also been shown to exert opposite effects. Ablation of neurogenesis does not lead to a depressive phenotype, but it can enhance responsiveness to stress and affect stress susceptibility. Monoaminergic-targeted antidepressants, environmental enrichment and adrenalectomy are beneficial for reversing stress-induced changes in behaviour and have been shown to do so in a neurogenesis-dependant manner. In addition, stress and antidepressants can affect hippocampal neurogenesis, preferentially in the ventral hippocampus. Together, these data show that adult hippocampal neurogenesis may play a role in the neuroendocrine and behavioural responses to stress, although it is not yet fully clear under which circumstances neurogenesis promotes resilience or susceptibility to stress. It will be important that future studies carefully examine how adult hippocampal neurogenesis can contribute to stress resilience/susceptibility so that it may be appropriately exploited for the development of new and more effective treatments for stress-related psychiatric disorders. Ablation of adult hippocampal NG can affect stress susceptibility. Increased hippocampal NG is associated with both susceptibility and resilience. Adult hippocampal NG can influence stress-induced alterations in HPA-axis activity. Behavioural effects of some but not all antidepressants are neurogenesis-dependent. Stress and antidepressants can affect NG preferentially in the ventral hippocampus.
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Affiliation(s)
- Brunno R Levone
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Ireland
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Ireland
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O'Leary OF, Cryan JF. A ventral view on antidepressant action: roles for adult hippocampal neurogenesis along the dorsoventral axis. Trends Pharmacol Sci 2014; 35:675-87. [PMID: 25455365 DOI: 10.1016/j.tips.2014.09.011] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [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: 07/26/2014] [Revised: 09/29/2014] [Accepted: 09/30/2014] [Indexed: 11/26/2022]
Abstract
Adult hippocampal neurogenesis is implicated in antidepressant action, stress responses, and cognitive functioning. The hippocampus is functionally segregated along its longitudinal axis into dorsal (dHi) and ventral (vHi) regions in rodents, and analogous posterior and anterior regions in primates, whereby the vHi preferentially regulates stress and anxiety, while the dHi preferentially regulates spatial learning and memory. Given the role of neurogenesis in functions preferentially regulated by the dHi or vHi, it is plausible that neurogenesis is preferentially regulated in either the dHi or vHi depending upon the stimulus. We appraise here the literature on the effects of stress and antidepressants on neurogenesis along the hippocampal longitudinal axis and explore whether preferential regulation of neurogenesis in the vHi/anterior hippocampus contributes to stress resilience and antidepressant action.
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Affiliation(s)
- Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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O'Leary OF, O'Brien FE, O'Connor RM, Cryan JF. Drugs, genes and the blues: Pharmacogenetics of the antidepressant response from mouse to man. Pharmacol Biochem Behav 2014; 123:55-76. [DOI: 10.1016/j.pbb.2013.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 10/04/2013] [Accepted: 10/16/2013] [Indexed: 12/11/2022]
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Naughton M, Clarke G, O'Leary OF, Cryan JF, Dinan TG. A review of ketamine in affective disorders: current evidence of clinical efficacy, limitations of use and pre-clinical evidence on proposed mechanisms of action. J Affect Disord 2014; 156:24-35. [PMID: 24388038 DOI: 10.1016/j.jad.2013.11.014] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [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: 10/06/2013] [Revised: 11/19/2013] [Accepted: 11/21/2013] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Recent research has seen low-dose ketamine emerge as a novel, rapid-acting antidepressant. Ketamine, an N-methy-d-aspartate (NMDA) receptor antagonist, leads to effects on the glutamatergic system and abnormalities in this neurotransmittor system are present in depression. This article aims to (1) review the clinical literature on low-dose ketamine as a rapid-acting antidepressant in affective disorders, (2) provide a critical overview of the limitations of ketamine and research attempts to overcome these (3) discuss the proposed mechanisms of action of ketamine and (4) point towards future research directions. METHOD The electronic database Pubmed, Web of Science and sciencedirect were searched using the keywords: ketamine, N-methyl-d-aspartate receptor antagonist, rapid-acting antidepressant, depression, treatment-resistant depression, bipolar depression, suicidal ideation, electroconvulsive therapy, mechanism of action. RESULT The literature demonstrates evidence supporting a rapid-acting antidepressant effect of low-dose intravenous ketamine in major depressive disorder, in bipolar depression and in depression with suicidal ideation. There are mixed results as to whether ketamine leads to a reduction in time to remission in patients undergoing electroconvulsive therapy (ECT). Efforts to unravel ketamine's therapeutic mechanism of action have implicated the mammalian target of rapamycin (mTOR)-dependent synapse formation in the rat prefrontal cortex, eukaryotic elongation factor 2 phosphorylation (p-eEF2) and glycogen synthase kinase (GSK-3). Ketamine's limiting factors are the transient nature of its antidepressant effect and concerns regarding abuse, and research efforts to overcome these are reviewed. CONCLUSION Current and future research studies are using ketamine as a promising tool to evaluate the glutamatergic neurotransmittor system to learn more about the pathophysiology of depression and develop more specific rapid-acting antidepressant treatments.
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Affiliation(s)
- Marie Naughton
- Department of Psychiatry, University College Cork, Western Road, Cork City, Cork, Ireland.
| | - Gerard Clarke
- Department of Psychiatry, University College Cork, Western Road, Cork City, Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
| | - Olivia F O'Leary
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
| | - John F Cryan
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
| | - Timothy G Dinan
- Department of Psychiatry, University College Cork, Western Road, Cork City, Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
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Abstract
Rodent models of depression have been developed in an effort to identify novel antidepressant compounds and to further our understanding of the pathophysiology of depression. Various rodent models of depression and antidepressant-like behaviour are currently used but, clearly, none of these current models fully recapitulate all features of depression. Moreover, these models have not resulted in the development of novel non-monoaminergic-based antidepressants with clinical efficacy. Thus, a refinement of the current models of depression is required. The present review outlines the most commonly used models of depression and antidepressant drug-like activity and suggests several factors that should be considered when refining these models.
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Affiliation(s)
- Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland,
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O'Connor RM, Pusceddu MM, O'Leary OF, Savignac HM, Bravo JA, El Yacoubi M, Vaugeois JM, Dinan TG, Cryan JF. Hippocampal group III mGlu receptor mRNA levels are not altered in specific mouse models of stress, depression and antidepressant action. Pharmacol Biochem Behav 2013; 103:561-7. [DOI: 10.1016/j.pbb.2012.09.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 08/31/2012] [Accepted: 09/23/2012] [Indexed: 12/31/2022]
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Felice D, O'Leary OF, Pizzo RC, Cryan JF. Blockade of the GABAB receptor increases neurogenesis in the ventral but not dorsal adult hippocampus: Relevance to antidepressant action. Neuropharmacology 2012; 63:1380-8. [DOI: 10.1016/j.neuropharm.2012.06.066] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 05/25/2012] [Accepted: 06/28/2012] [Indexed: 11/29/2022]
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Moloney RD, O'Leary OF, Felice D, Bettler B, Dinan TG, Cryan JF. Early-life stress induces visceral hypersensitivity in mice. Neurosci Lett 2012; 512:99-102. [PMID: 22326388 DOI: 10.1016/j.neulet.2012.01.066] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/26/2012] [Accepted: 01/27/2012] [Indexed: 12/23/2022]
Abstract
Early-life stress is a risk factor for irritable bowel syndrome (IBS), a common and debilitating functional gastrointestinal disorder that is often co-morbid with stress-related psychiatric disorders. In the rat, maternal separation (MS) stress has been shown to induce visceral hypersensitivity in adulthood and thus has become a useful model of IBS. However, development of mouse models of maternal separation has been difficult. Given the advent of transgenic mouse technology, such models would be useful to further our understanding of the pathophysiology of IBS and to develop new pharmacological treatments. Thus, the present study aimed to develop a mouse model of MS stress-induced visceral hyperalgesia as measured using manometric recordings of colorectal distension (CRD). Moreover, since the GABA(B) receptor has been reported to play a role in pain processes, we also assessed its role in visceral nociception using novel GABA(B(1b)) receptor subunit knockout mice. CRD was performed in adult male wildtype and GABA(B(1b)) receptor knockout mice that had undergone unpredictable MS combined with unpredictable maternal stress (MSUS) from postnatal day 1 through 14 (PND 1-14). MSUS induced visceral hypersensitivity in both wildtype and GABA(B(1b)) receptor knockout mice when compared with non-stressed mice. Wildtype and GABA(B(1b)) receptor knockout mice did not differ in baseline or stress-induced visceral sensitivity. To the best of our knowledge, this is the first study to show that early-life stress induces visceral hypersensitivity in a mouse model. These findings may provide a novel mouse model of visceral hypersensitivity which may aid our understanding of its underlying mechanisms in future studies.
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Affiliation(s)
- Rachel D Moloney
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Ireland
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Affiliation(s)
- John F Cryan
- School of Pharmacy, Department of Pharmacology and Therapeutics, Alimentary Pharmabiotic Centre, University College Cork, College Road, Cork, Ireland.
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O'Leary OF, Wu X, Castren E. Chronic fluoxetine treatment increases expression of synaptic proteins in the hippocampus of the ovariectomized rat: role of BDNF signalling. Psychoneuroendocrinology 2009; 34:367-81. [PMID: 18977602 DOI: 10.1016/j.psyneuen.2008.09.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/23/2008] [Accepted: 09/24/2008] [Indexed: 01/27/2023]
Abstract
Antidepressant drugs have been suggested to regulate synaptic transmission and structure. We hypothesised that antidepressant-induced changes in synapses and their associated proteins might become more apparent if they were measured under conditions of reduced synapse density. Therefore, in the present study, we examined whether chronic treatment with the antidepressant, fluoxetine alters expression of synaptic proteins in the hippocampus of rodents that underwent ovariectomy, a procedure which reportedly decreases synapse density in the CA1 region of the rat hippocampus. Using Western blotting, we measured changes in hippocampal expression of proteins associated with synapse structure, strength and activity namely, postsynaptic density protein 95 (PSD-95), the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) subunit GluR1 and phosphosynapsin (Ser9), respectively. We found that fluoxetine treatment increased expression of phosphosynapsin, PSD-95 and synaptic GluR1 (but not total GluR1) in the hippocampus of ovariectomized but not sham rats. Since BDNF and signalling at its receptor, TrkB, can mediate behavioural responses to antidepressants and induce neuronal plasticity, we investigated the contribution of TrkB signalling to fluoxetine-induced changes in synaptic protein expression by using a transgenic mouse model overexpressing a truncated form of the TrkB receptor (TrkB.T1). Fluoxetine produced a small but significant increase in hippocampal PSD-95 in ovariectomized wildtype mice but not in ovariectomized TrkB.T1 mice or sham mice. In contrast to rats, fluoxetine did not alter expression of synaptic GluR1 and did not reverse ovariectomy-induced decreases in hippocampal phosphosynapsin in either genotype. Taken together, these results suggest that chronic fluoxetine treatment can increase synaptic protein expression in the hippocampus and at least some of these effects require TrkB signalling. Moreover, these effects were only observed in ovariectomized animals, thus suggesting that fluoxetine-induced increases in synaptic protein levels might only occur or become detectable when hippocampal synaptic connectivity is perturbed.
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Maya Vetencourt JF, Sale A, Viegi A, Baroncelli L, De Pasquale R, O'Leary OF, Castrén E, Maffei L. The antidepressant fluoxetine restores plasticity in the adult visual cortex. Science 2008; 320:385-8. [PMID: 18420937 DOI: 10.1126/science.1150516] [Citation(s) in RCA: 653] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We investigated whether fluoxetine, a widely prescribed medication for treatment of depression, restores neuronal plasticity in the adult visual system of the rat. We found that chronic administration of fluoxetine reinstates ocular dominance plasticity in adulthood and promotes the recovery of visual functions in adult amblyopic animals, as tested electrophysiologically and behaviorally. These effects were accompanied by reduced intracortical inhibition and increased expression of brain-derived neurotrophic factor in the visual cortex. Cortical administration of diazepam prevented the effects induced by fluoxetine, indicating that the reduction of intracortical inhibition promotes visual cortical plasticity in the adult. Our results suggest a potential clinical application for fluoxetine in amblyopia as well as new mechanisms for the therapeutic effects of antidepressants and for the pathophysiology of mood disorders.
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O'Leary OF, Bechtholt AJ, Crowley JJ, Hill TE, Page ME, Lucki I. Depletion of serotonin and catecholamines block the acute behavioral response to different classes of antidepressant drugs in the mouse tail suspension test. Psychopharmacology (Berl) 2007; 192:357-71. [PMID: 17318507 DOI: 10.1007/s00213-007-0728-9] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 01/26/2007] [Indexed: 11/29/2022]
Abstract
RATIONALE Few studies have investigated whether the behavioral effects elicited by different types of antidepressant drugs are mediated by either serotonin (5-HT) or the catecholamines norepinephrine (NE) and dopamine (DA). OBJECTIVES By depleting 5-HT, or NE and DA, the present study investigated the contributions of these monoamines to the acute behavioral effects of selective serotonin reuptake inhibitors (SSRIs; fluoxetine and citalopram) and norepinephrine reuptake inhibitors (NRIs; desipramine and reboxetine) in the mouse tail suspension test (TST). RESULTS Depletion of 5-HT tissue content by para-chlorophenylalanine (PCPA), an inhibitor of tryptophan hydroxylase, completely blocked reductions of immobility by the SSRIs in the TST. In contrast, PCPA did not alter the behavioral effects of the NRIs. Inhibition of catecholamine synthesis by alpha-methyl-para-tyrosine (AMPT) reduced brain NE and DA tissue content, whereas disruption of vesicular storage with reserpine decreased brain NE, DA and 5-HT tissue content. However, neither treatment completely prevented responses to desipramine, fluoxetine, or citalopram in the TST. Depleting both newly synthesized and vesicular components of NE and DA transmission with a combination of reserpine and AMPT completely prevented the behavioral effects of desipramine, reboxetine, and fluoxetine and attenuated those of citalopram. Although PCPA did not alter baseline immobility, AMPT and reserpine increased baseline values in the TST. CONCLUSIONS These studies demonstrated that endogenous 5-HT synthesis mediates the behavioral effects of SSRIs, but not NRIs, in the TST. In contrast, disruption of the behavioral effects of NRI and SSRI antidepressants required disruption of both catecholamine synthesis and vesicular storage and release mechanisms.
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Affiliation(s)
- Olivia F O'Leary
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA
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O'Leary OF, Bechtholt AJ, Crowley JJ, Valentino RJ, Lucki I. The role of noradrenergic tone in the dorsal raphe nucleus of the mouse in the acute behavioral effects of antidepressant drugs. Eur Neuropsychopharmacol 2007; 17:215-26. [PMID: 16997535 DOI: 10.1016/j.euroneuro.2006.06.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 05/25/2006] [Accepted: 06/20/2006] [Indexed: 10/24/2022]
Abstract
Serotonin neurons of the dorsal raphe nucleus (DRN) receive dense noradrenergic innervation and are under tonic activation by noradrenergic input. Thus, afferent noradrenergic input to the DRN could modify the antidepressant effects of selective serotonin reuptake inhibitors (SSRIs) by regulating serotonergic transmission. This study investigated whether noradrenergic innervation of the DRN contributes to the acute behavioral effects of different types of antidepressant drugs in the mouse tail suspension test (TST). Noradrenergic terminals in the DRN were destroyed selectively by the local application of 6-hydroxydopamine (6-OHDA). Immunohistochemical analysis confirmed the presence of noradrenergic fibers in the mouse DRN, that 6-OHDA-induced destruction of noradrenergic terminals was confined to the DRN, and serotonergic cell bodies were not affected by 6-OHDA treatment. The antidepressants tested included the SSRIs, fluoxetine and citalopram, and the norepinephrine reuptake inhibitor (NRI) desipramine. The behavioral effects of fluoxetine (20 mg/kg, IP) were blocked by the destruction of noradrenergic terminals. In contrast, pretreatment with 6-OHDA did not alter the ability of citalopram (20 mg/kg, IP) or desipramine (10 mg/kg, IP) to reduce immobility in the TST. Destruction of noradrenergic projections from the locus ceruleus (LC) by DSP-4 treatment did not alter the behavioral effects of any of the antidepressants tested, or the presence of noradrenergic terminals in the DRN, thus indicating that noradrenergic pathways originating from the LC do not mediate the acute behavioral effects of antidepressants in this test. Thus, afferent noradrenergic activity at the level of the DRN can modulate serotonergic transmission in forebrain structures and the behavioral effects of SSRIs, such as fluoxetine, which use noradrenergic input to the DRN to increase forebrain serotonin.
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Affiliation(s)
- Olivia F O'Leary
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Sairanen M, O'Leary OF, Knuuttila JE, Castrén E. Chronic antidepressant treatment selectively increases expression of plasticity-related proteins in the hippocampus and medial prefrontal cortex of the rat. Neuroscience 2006; 144:368-74. [PMID: 17049169 DOI: 10.1016/j.neuroscience.2006.08.069] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/16/2006] [Accepted: 08/31/2006] [Indexed: 02/07/2023]
Abstract
Antidepressants protect against hippocampal volume loss in humans and reverse stress-induced atrophic changes in animals thus supporting the hypothesis that the pathophysiology of stress-related disorders such as depression involves reductions in neuronal connectivity and this effect is reversible by antidepressant treatment. However, it is unclear which brain areas demonstrate such alterations in plasticity in response to antidepressant treatment. The aim of the present study was to examine the effect of antidepressant treatment on the expression of three plasticity-associated marker proteins, the polysialylated form of nerve cell adhesion molecule (PSA-NCAM), phosphorylated cyclic-AMP response element binding protein (pCREB) and growth-associated protein 43 (GAP-43), in the rat brain. To this end, rats were treated either acutely (60 min) or chronically (21 days) with imipramine (30 and 15 mg/kg, respectively) and the expression of PSA-NCAM, pCREB, and GAP-43 was assessed using immunohistochemistry. Initial mapping revealed that chronic imipramine treatment increased expression of these plasticity-associated proteins in the hippocampus, medial prefrontal cortex and piriform cortex but not in the other brain regions examined. Since PSA-NCAM and pCREB are expressed in recently-generated neurons in the dentate gyrus, it is likely that chronic imipramine treatment increased their expression in the hippocampus at least partially by increasing neurogenesis. In contrast, since chronic imipramine treatment is not associated with neurogenesis in the medial prefrontal cortex, increased expression of PSA-NCAM and pCREB in the prelimbic cortex implicates changes in synaptic connectivity in this brain region. Acute treatment with imipramine increased the number of pCREB positive nuclei in the hippocampus and the prefrontal cortex but did not alter expression of GAP-43 or PSA-NCAM in any of the brain regions examined. Taken together, the results of the present study suggest that antidepressant treatment increases synaptic plasticity and connectivity in brain regions associated with mood disorders.
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Affiliation(s)
- M Sairanen
- Sigrid Jusélius Laboratory, Neuroscience Center, University of Helsinki, P.O. Box 56, 00014 University of Helsinki, Helsinki, Finland
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Crowley JJ, Jones MD, O'Leary OF, Lucki I. Automated tests for measuring the effects of antidepressants in mice. Pharmacol Biochem Behav 2005; 78:269-74. [PMID: 15219767 DOI: 10.1016/j.pbb.2004.03.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Revised: 03/18/2004] [Accepted: 03/29/2004] [Indexed: 11/26/2022]
Abstract
The forced swim test (FST) and the tail suspension test (TST) are used widely for measuring the pharmacological effects of antidepressant drugs or changes in stress-evoked behavior in mice. However, inconsistent scoring techniques and poor reproducibility may result from their reliance on subjective ratings by observers to score behavioral changes. In this paper, automated versions of the mouse FST and TST were characterized and validated against observer ratings. For the FST, a commercially available video tracking system (SMART II; San Diego Instruments) measured the duration that mice swam in water-filled cylinders at a set velocity. For the TST, a commercially available automated device (Med Associates, St. Albans, VT) measured input from a strain gauge to detect movements of mice suspended from an elevated bar. Dose-dependent effects of the antidepressant desipramine on FST and TST immobility were measured in CD-1 mice using both automated devices and manual scoring from videotapes. Similar dose-response curves were obtained using both methods. However, a wide range of correlations for raters in the FST indicated that scoring criteria varied for individual raters despite similar instructions. Automated versions of the mouse FST and TST are now available and provide several advantages, including an opportunity to standardize methods across laboratories.
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Affiliation(s)
- James J Crowley
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Cryan JF, O'Leary OF, Jin SH, Friedland JC, Ouyang M, Hirsch BR, Page ME, Dalvi A, Thomas SA, Lucki I. Norepinephrine-deficient mice lack responses to antidepressant drugs, including selective serotonin reuptake inhibitors. Proc Natl Acad Sci U S A 2004; 101:8186-91. [PMID: 15148402 PMCID: PMC419578 DOI: 10.1073/pnas.0401080101] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mice unable to synthesize norepinephrine (NE) and epinephrine due to targeted disruption of the dopamine beta-hydroxylase gene, Dbh, were used to critically test roles for NE in mediating acute behavioral changes elicited by different classes of antidepressants. To this end, we used the tail suspension test, one of the most widely used paradigms for assessing antidepressant activity and depression-related behaviors in normal and genetically modified mice. Dbh(-/-) mice failed to respond to the behavioral effects of various antidepressants, including the NE reuptake inhibitors desipramine and reboxetine, the monoamine oxidase inhibitor pargyline, and the atypical antidepressant bupropion, even though they did not differ in baseline immobility from Dbh(+/-) mice, which have normal levels of NE. Surprisingly, the effects of the selective serotonin reuptake inhibitors (SSRIs) fluoxetine, sertraline, and paroxetine were also absent or severely attenuated in the Dbh(-/-) mice. In contrast, citalopram (the most selective SSRI) was equally effective at reducing immobility in mice with and without NE. Restoration of NE by using L-threo-3,4-dihydroxyphenylserine reinstated the behavioral effects of both desipramine and paroxetine in Dbh(-/-) mice, thus demonstrating that the reduced sensitivity to antidepressants is related to NE function, as opposed to developmental abnormalities resulting from chronic NE deficiency. Microdialysis studies demonstrated that the ability of fluoxetine to increase hippocampal serotonin was blocked in Dbh(-/-) mice, whereas citalopram's effect was only partially attenuated. These data show that NE plays an important role in mediating acute behavioral and neurochemical actions of many antidepressants, including most SSRIs.
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Affiliation(s)
- John F Cryan
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
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Lucki I, O'Leary OF. Distinguishing roles for norepinephrine and serotonin in the behavioral effects of antidepressant drugs. J Clin Psychiatry 2004; 65 Suppl 4:11-24. [PMID: 15046537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Antidepressant drugs have typically been classified into sets of compounds with actions targeted at serotonin (selective serotonin reuptake inhibitors [SSRIs]), norepinephrine (norepinephrine reuptake inhibitors [NRIs]), or both neurotransmitters (serotonin-norepinephrine reuptake inhibitors). Their classification has been based predominantly on their acute pharmacologic effects, usually determined by in vitro radioligand binding assays. The pharmacologic selectivity of antidepressants can be altered after their systemic administration, however, by dose, drug metabolism, physiologic interactions between neurotransmitters, and adaptive effects that emerge after chronic administration. This review examines whether pharmacologic selectivity is maintained by different types of antidepressants in vivo and whether pharmacologic selectivity matters for the production of their behavioral effects. Antidepressants increase extracellular levels of neurotransmitters according to their ability to inhibit presynaptic transporters, although physiologic interactions among neurotransmitters can influence antidepressants' selectivity in certain brain regions. Chronic administration of many antidepressants also causes down-regulation of postsynaptic and presynaptic receptors. The pattern of responses of presynaptic markers suggests that pharmacologic selectivity is maintained after chronic administration of many antidepressants. Behavioral tests indicate that depletion of serotonin (5-HT) is capable of preventing the effects produced by SSRIs but not NRIs. The depletion of catecholamines also inhibits the effects of NRIs, although test results can be complicated by inhibition of motor activity. Depletion of norepinephrine may also inhibit the effects of some SSRIs, but not highly selective SSRIs like citalopram. Although the pattern of results from in vivo tests supports the concept that parallel neurotransmitter mechanisms lead to antidepressant activity, norepinephrine may participate in the effects of some SSRIs. It is also possible that compounds with dual actions at 5-HT and norepinephrine systems may be effective under circumstances in which selective antidepressants are ineffective.
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Affiliation(s)
- Irwin Lucki
- Department of Psychiatry, University of Pennsylvania, Philadelphia 19104, USA.
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