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Pagliusi M, Amorim-Marques AP, Lobo MK, Guimarães FS, Lisboa SF, Gomes FV. The rostral ventromedial medulla modulates pain and depression-related behaviors caused by social stress. Pain 2024:00006396-990000000-00582. [PMID: 38661577 DOI: 10.1097/j.pain.0000000000003257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/18/2023] [Indexed: 04/26/2024]
Abstract
ABSTRACT The rostral ventromedial medulla (RVM) is a crucial structure in the descending pain modulatory system, playing a key role as a relay for both the facilitation and inhibition of pain. The chronic social defeat stress (CSDS) model has been widely used to study stress-induced behavioral impairments associated with depression in rodents. Several studies suggest that CSDS also causes changes related to chronic pain. In this study, we aimed to investigate the involvement of the RVM in CSDS-induced behavioral impairments, including those associated with chronic pain. We used chemogenetics to activate or inhibit the RVM during stress. The results indicated that the RVM is a vital hub influencing stress outcomes. Rostral ventromedial medulla activation during CSDS ameliorates all the stress outcomes, including social avoidance, allodynia, hyperalgesia, anhedonia, and behavioral despair. In addition, RVM inhibition in animals exposed to a subthreshold social defeat stress protocol induces a susceptible phenotype, facilitating all stress outcomes. Finally, chronic RVM inhibition-without any social stress stimulus-induces chronic pain but not depressive-like behaviors. Our findings provide insights into the comorbidity between chronic pain and depression by indicating the involvement of the RVM in establishing social stress-induced behavioral responses associated with both chronic pain and depression.
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Affiliation(s)
- Marco Pagliusi
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Anna P Amorim-Marques
- Department of Biomolecular Sciences, Ribeirão Preto Pharmaceutical Sciences School, University of São Paulo, Ribeirão Preto, Brazil
| | - Mary Kay Lobo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Francisco S Guimarães
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Sabrina F Lisboa
- Department of Biomolecular Sciences, Ribeirão Preto Pharmaceutical Sciences School, University of São Paulo, Ribeirão Preto, Brazil
| | - Felipe V Gomes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
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2
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Activation of 5-HT3 receptors in the medulla oblongata is involved in the phasic control of urinary bladder. Neurosci Lett 2022; 790:136886. [PMID: 36179901 DOI: 10.1016/j.neulet.2022.136886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/13/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022]
Abstract
The control of micturition depends on reflex mechanisms, however, it undergoes modulation from cortex, pons and medullary areas. This study investigated if the activation of 5-HT3 receptors in the medulla influences the urinary bladder (UB) regulation in rats. Isoflurane female Wistar rats were submitted to catheterization of the femoral artery and vein for mean arterial pressure (MAP) and heart rate (HR) recordings and injection of drugs, respectively. The UB was cannulated for intravesical pressure (IP) measurement. The Doppler flow probe was placed around the left renal artery for renal conductance (RC) recordings. Phenylbiguanide (PB) and granisetron (GN) were injected into the 4th brain ventricle in rats with guide cannulas implanted 5 days prior to the experiments; or PB and GN were randomly injected intravenously or applied topically (in situ) on the UB. PB injection into 4th V significantly increased IP (68.67 ± 11.70%) and decreased MAP (-29 ± 6 mmHg) compared to saline (0.34 ± 0.64% and -2 ± 2 mmHg), with no changes in the HR and RC. GN injection into the 4th V did not significantly change the IP and RC compared to saline, nevertheless, significantly increased MAP (25 ± 4 mmHg) and heart rate (36 ± 9 bpm) compared to saline. Intravenous PB and GN only produced cardiovascular effects, whilst PB but not GN in situ on the UB evoked increase in IP (111.60 ± 30.36%). Therefore, the activation of 5HT-3 receptors in medullary areas increases the intravesical pressure and these receptors are involved in the phasic control of UB. In contrast, 5-HT3 receptors in the medulla oblongata are involved in the pathways of the tonic control of the cardiovascular system. The activation of 5-HT3 receptors in the bladder cause increase in intravesical pressure and this regulation seem to be under phasic control as the blockade of such receptors elicits no changes in baseline intravesical pressure.
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3
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Behl T, Kaur I, Sehgal A, Singh S, Makeen HA, Albratty M, Alhazmi HA, Bhatia S, Bungau S. The Locus Coeruleus - Noradrenaline system: Looking into Alzheimer's therapeutics with rose coloured glasses. Biomed Pharmacother 2022; 151:113179. [PMID: 35676784 DOI: 10.1016/j.biopha.2022.113179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/17/2022] [Accepted: 05/22/2022] [Indexed: 11/16/2022] Open
Abstract
Owing to the challenging ethos of global healthcare system, the Alzheimer's Disease (AD) researchers are consistently striving for a suitable target for disease amelioration. Besides the neurotransmitter release by neurons, the cells release tau proteins and amyloid peptides, within the extracellular vacancies, aggregating into tangles and plaques (AD pathological hallmarks). During neuro-stimulation, release of neuromodulator noradrenaline (NA), contained in the locus coeruleus (LC), exerts a significant impact on the neurons and microglia. The production of amyloid-β (Aβ) and hyperphosphorylation of tau proteins are affected by the α2A and β adrenoreceptors, parallel to influencing their clearance. The manuscript entails a detailed understanding of the LC-NA system, as a possible avenue in AD management. The authors provide a comprehensive data on AD pathology and its link with LC neuroanatomical projections, followed by the pathogenic implications of LC-NA system in AD. The data also integrates numerous studies from online databases, evidently supporting the loss of the system integrity in AD patients, and the impact of the sympathetic system on specific AD hallmarks. Thus, the objective of this review is to compile a wide compendium of studies, for the convenience of the neuro-researchers, aiding in the establishment of a suitable therapeutic regimen for AD treatment.
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Affiliation(s)
- Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania.
| | - Ishnoor Kaur
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Sukhbir Singh
- Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Hafiz A Makeen
- Pharmacy Practice Research Unit, Clinical Pharmacy Department, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Mohammed Albratty
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Hassan A Alhazmi
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, Jazan, Saudi Arabia; Substance Abuse and Toxicology Research Centre, Jazan University, Jazan, Saudi Arabia; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Saurabh Bhatia
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman; School of Health Science, University of Petroleum and Energy Studies, Dehradun, India; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea, Romania; Doctoral School of Biomedical Sciences, University of Oradea, Oradea, Romania.
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Singh K, García-Gomar MG, Cauzzo S, Staab JP, Indovina I, Bianciardi M. Structural connectivity of autonomic, pain, limbic, and sensory brainstem nuclei in living humans based on 7 Tesla and 3 Tesla MRI. Hum Brain Mapp 2022; 43:3086-3112. [PMID: 35305272 PMCID: PMC9188976 DOI: 10.1002/hbm.25836] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/09/2022] [Accepted: 03/06/2022] [Indexed: 11/18/2022] Open
Abstract
Autonomic, pain, limbic, and sensory processes are mainly governed by the central nervous system, with brainstem nuclei as relay centers for these crucial functions. Yet, the structural connectivity of brainstem nuclei in living humans remains understudied. These tiny structures are difficult to locate using conventional in vivo MRI, and ex vivo brainstem nuclei atlases lack precise and automatic transformability to in vivo images. To fill this gap, we mapped our recently developed probabilistic brainstem nuclei atlas developed in living humans to high‐spatial resolution (1.7 mm isotropic) and diffusion weighted imaging (DWI) at 7 Tesla in 20 healthy participants. To demonstrate clinical translatability, we also acquired 3 Tesla DWI with conventional resolution (2.5 mm isotropic) in the same participants. Results showed the structural connectome of 15 autonomic, pain, limbic, and sensory (including vestibular) brainstem nuclei/nuclei complex (superior/inferior colliculi, ventral tegmental area‐parabrachial pigmented, microcellular tegmental–parabigeminal, lateral/medial parabrachial, vestibular, superior olivary, superior/inferior medullary reticular formation, viscerosensory motor, raphe magnus/pallidus/obscurus, parvicellular reticular nucleus‐alpha part), derived from probabilistic tractography computation. Through graph measure analysis, we identified network hubs and demonstrated high intercommunity communication in these nuclei. We found good (r = .5) translational capability of the 7 Tesla connectome to clinical (i.e., 3 Tesla) datasets. Furthermore, we validated the structural connectome by building diagrams of autonomic/pain/limbic connectivity, vestibular connectivity, and their interactions, and by inspecting the presence of specific links based on human and animal literature. These findings offer a baseline for studies of these brainstem nuclei and their functions in health and disease, including autonomic dysfunction, chronic pain, psychiatric, and vestibular disorders.
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Affiliation(s)
- Kavita Singh
- Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - María Guadalupe García-Gomar
- Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.,Escuela Nacional de Estudios Superiores, Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Mexico
| | - Simone Cauzzo
- Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.,Life Sciences Institute, Sant'Anna School of Advanced Studies, Pisa, Italy.,Research Center E. Piaggio, University of Pisa, Pisa, Italy
| | - Jeffrey P Staab
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Otorhinolaryngology - Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Iole Indovina
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy.,Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Marta Bianciardi
- Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.,Division of Sleep Medicine, Harvard University, Boston, Massachusetts, USA
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Costa-Pereira JT, Ribeiro J, Martins I, Tavares I. Role of Spinal Cord α 2-Adrenoreceptors in Noradrenergic Inhibition of Nociceptive Transmission During Chemotherapy-Induced Peripheral Neuropathy. Front Neurosci 2020; 13:1413. [PMID: 32009887 PMCID: PMC6974806 DOI: 10.3389/fnins.2019.01413] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a problem during cancer treatment and for cancer survivors but the central mechanisms underlying CIPN remain understudied. This study aims to determine if CIPN is associated with alterations of noradrenergic modulation of nociceptive transmission at the spinal cord. CIPN was induced in male Wistar rats by paclitaxel injections. One month after CIPN induction, the behavioral effects of the administration of reboxetine (noradrenaline reuptake inhibitor), clonidine (agonist of α2-adrenoreceptors; α2–AR) and atipamezole (antagonist of α2–AR) were evaluated using the von Frey and cold plate tests. Furthermore, we measured the expression of the noradrenaline biosynthetic enzyme dopamine-β-hydroxylase (DBH) and of α2–AR in the spinal dorsal horn. Reboxetine and clonidine reversed the behavioral signs of CIPN whereas the opposite occurred with atipamezole. In the 3 pharmacological approaches, a higher effect was detected in mechanical allodynia, the pain modality which is under descending noradrenergic control. DBH expression was increased at the spinal dorsal horn of paclitaxel-injected animals. The enhanced noradrenergic inhibition during CIPN may represent an adaptation of the descending noradrenergic pain control system to the increased arrival of peripheral nociceptive input. A potentiation of the α2–AR mediated antinociception at the spinal cord may represent a therapeutic opportunity to face CIPN.
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Affiliation(s)
- José Tiago Costa-Pereira
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Joana Ribeiro
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Isabel Martins
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Isaura Tavares
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
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6
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Vila-Pueyo M, Hoffmann J, Romero-Reyes M, Akerman S. Brain structure and function related to headache: Brainstem structure and function in headache. Cephalalgia 2018; 39:1635-1660. [PMID: 29969040 DOI: 10.1177/0333102418784698] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE To review and discuss the literature relevant to the role of brainstem structure and function in headache. BACKGROUND Primary headache disorders, such as migraine and cluster headache, are considered disorders of the brain. As well as head-related pain, these headache disorders are also associated with other neurological symptoms, such as those related to sensory, homeostatic, autonomic, cognitive and affective processing that can all occur before, during or even after headache has ceased. Many imaging studies demonstrate activation in brainstem areas that appear specifically associated with headache disorders, especially migraine, which may be related to the mechanisms of many of these symptoms. This is further supported by preclinical studies, which demonstrate that modulation of specific brainstem nuclei alters sensory processing relevant to these symptoms, including headache, cranial autonomic responses and homeostatic mechanisms. REVIEW FOCUS This review will specifically focus on the role of brainstem structures relevant to primary headaches, including medullary, pontine, and midbrain, and describe their functional role and how they relate to mechanisms of primary headaches, especially migraine.
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Affiliation(s)
- Marta Vila-Pueyo
- Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Jan Hoffmann
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marcela Romero-Reyes
- Department of Neural and Pain Sciences, University of Maryland Baltimore, Baltimore, MD, USA
| | - Simon Akerman
- Department of Neural and Pain Sciences, University of Maryland Baltimore, Baltimore, MD, USA
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7
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A Pontine Region is a Neural Correlate of the Human Affective Processing Network. EBioMedicine 2016; 2:1799-805. [PMID: 26870804 PMCID: PMC4740328 DOI: 10.1016/j.ebiom.2015.10.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/15/2015] [Accepted: 10/19/2015] [Indexed: 11/22/2022] Open
Abstract
The in vivo neural activity of the pons during the perception of affective stimuli has not been studied despite the strong implications of its role in affective processing. To examine the activity of the pons during the viewing of affective stimuli, and to verify its functional and structural connectivity with other affective neural correlates, a multimodal magnetic resonance imaging methodology was employed in this study. We observed the in vivo activity of the pons when viewing affective stimuli. Furthermore, small-world connectivity indicated that the functional connectivity (FC) between the pons and the cortico-limbic affective regions was meaningful, with the coefficient λ being positively associated with self-reported emotional reactivity. The FC between the pons and the cortico-limbic-striatal areas was related to self-reported negative affect. Corroborating this finding was the observation that the tract passing through the pons and the left hippocampus was negatively related to self-reported positive affect and positively correlated with emotional reactivity. Our findings support the framework that the pons works conjunctively with the distributed cortico-limbic-striatal systems in shaping individuals' affective states and reactivity. Our work paves the path for future research on the contribution of the pons to the precipitation and maintenance of affective disorders.
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8
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Lopes LT, Patrone LGA, Li KY, Imber AN, Graham CD, Gargaglioni LH, Putnam RW. Anatomical and functional connections between the locus coeruleus and the nucleus tractus solitarius in neonatal rats. Neuroscience 2016; 324:446-68. [PMID: 27001176 PMCID: PMC4841468 DOI: 10.1016/j.neuroscience.2016.03.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/25/2016] [Accepted: 03/14/2016] [Indexed: 11/29/2022]
Abstract
This study was designed to investigate brain connections among chemosensitive areas in newborn rats. Rhodamine beads were injected unilaterally into the locus coeruleus (LC) or into the caudal part of the nucleus tractus solitarius (cNTS) in Sprague-Dawley rat pups (P7-P10). Rhodamine-labeled neurons were patched in brainstem slices to study their electrophysiological responses to hypercapnia and to determine if chemosensitive neurons are communicating between LC and cNTS regions. After 7-10 days, retrograde labeling was observed in numerous areas of the brainstem, including many chemosensitive regions, such as the contralateral LC, cNTS and medullary raphe. Whole-cell patch clamp was done in cNTS. In 4 of 5 retrogradely labeled cNTS neurons that projected to the LC, firing rate increased in response to hypercapnic acidosis (15% CO2), even in synaptic blockade medium (SNB) (high Mg(2+)/low Ca(2+)). In contrast, 2 of 3 retrogradely labeled LC neurons that projected to cNTS had reduced firing rate in response to hypercapnic acidosis, both in the presence and absence of SNB. Extensive anatomical connections among chemosensitive brainstem regions in newborn rats were found and at least for the LC and cNTS, the connections involve some CO2-sensitive neurons. Such anatomical and functional coupling suggests a complex central respiratory control network, such as seen in adult rats, is already largely present in neonatal rats by at least day P7-P10. Since the NTS and the LC play a major role in memory consolidation, our results may also contribute to the understanding of the development of memory consolidation.
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Affiliation(s)
- L T Lopes
- Dept of Animal Morphology and Physiology. São Paulo State University, FCAV, Jaboticabal, SP, Brazil
| | - L G A Patrone
- Dept of Animal Morphology and Physiology. São Paulo State University, FCAV, Jaboticabal, SP, Brazil
| | - K-Y Li
- Dept of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - A N Imber
- Dept of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - C D Graham
- Dept of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - L H Gargaglioni
- Dept of Animal Morphology and Physiology. São Paulo State University, FCAV, Jaboticabal, SP, Brazil
| | - R W Putnam
- Dept of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA.
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Baker PM, Oh SE, Kidder KS, Mizumori SJY. Ongoing behavioral state information signaled in the lateral habenula guides choice flexibility in freely moving rats. Front Behav Neurosci 2015; 9:295. [PMID: 26582981 PMCID: PMC4631824 DOI: 10.3389/fnbeh.2015.00295] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/19/2015] [Indexed: 12/18/2022] Open
Abstract
The lateral habenula (LHb) plays a role in a wide variety of behaviors ranging from maternal care, to sleep, to various forms of cognition. One prominent theory with ample supporting evidence is that the LHb serves to relay basal ganglia and limbic signals about negative outcomes to midbrain monoaminergic systems. This makes it likely that the LHb is critically involved in behavioral flexibility as all of these systems have been shown to contribute when flexible behavior is required. Behavioral flexibility is commonly examined across species and is impaired in various neuropsychiatric conditions including autism, depression, addiction, and schizophrenia; conditions in which the LHb is thought to play a role. Therefore, a thorough examination of the role of the LHb in behavioral flexibility serves multiple functions including understanding possible connections with neuropsychiatric illnesses and additional insight into its role in cognition in general. Here, we assess the LHb’s role in behavioral flexibility through comparisons of the roles its afferent and efferent pathways are known to play. Additionally, we provide new evidence supporting the LHb contributions to behavioral flexibility through organization of specific goal directed actions under cognitively demanding conditions. Specifically, in the first experiment, a majority of neurons recorded from the LHb were found to correlate with velocity on a spatial navigation task and did not change significantly when reward outcomes were manipulated. Additionally, measurements of local field potential (LFP) in the theta band revealed significant changes in power relative to velocity and reward location. In a second set of experiments, inactivation of the LHb with the gamma-aminobutyric acid (GABA) agonists baclofen and muscimol led to an impairment in a spatial/response based repeated probabilistic reversal learning task. Control experiments revealed that this impairment was likely due to the demands of repeated switching behaviors as rats were unimpaired on initial discrimination acquisition or retention of probabilistic learning. Taken together, these novel findings compliment other work discussed supporting a role for the LHb in action selection when cognitive or emotional demands are increased. Finally, we discuss future mechanisms by which a superior understanding of the LHb can be obtained through additional examination of behavioral flexibility tasks.
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Affiliation(s)
- Phillip M Baker
- Department of Psychology, University of Washington Seattle, WA, USA
| | - Sujean E Oh
- Department of Psychology, University of Washington Seattle, WA, USA
| | - Kevan S Kidder
- Department of Psychology, University of Washington Seattle, WA, USA
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Hosford PS, Millar J, Ramage AG. Cardiovascular afferents cause the release of 5-HT in the nucleus tractus solitarii; this release is regulated by the low- (PMAT) not the high-affinity transporter (SERT). J Physiol 2015; 593:1715-29. [PMID: 25694117 PMCID: PMC4386968 DOI: 10.1113/jphysiol.2014.285312] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/16/2015] [Indexed: 12/31/2022] Open
Abstract
The nucleus tractus solitarii (NTS) integrates inputs from cardiovascular afferents and thus is crucial for cardiovascular homeostasis. These afferents primarily release glutamate, although 5-HT has also been shown to play a role in their actions. Using fast-cyclic voltammetry, an increase in 5-HT concentrations (range 12-50 nm) could be detected in the NTS in anaesthetized rats in response to electrical stimulation of the vagus and activation of cardiopulmonary, chemo- and baroreceptor reflexes. This 5-HT signal was not potentiated by the serotonin transporter (SERT) or the noradrenaline transporter (NET) inhibitors citalopram and desipramine (1 mg kg(-1) ). However, decynium-22 (600 μg kg(-1) ), an organic cation 3 transporter (OCT3)/plasma membrane monoamine transporter (PMAT) inhibitor, increased the 5-HT signal by 111 ± 21% from 29 ± 10 nm. The effectiveness of these inhibitors was tested against the removal time of 5-HT and noradrenaline applied by microinjection to the NTS. Citalopram and decynium-22 attenuated the removal of 5-HT but not noradrenaline, whereas desipramine had the reverse action. The OCT3 inhibitor corticosterone (10 mg kg(-1) ) had no effect. Blockade of glutamate receptors with topical kynurenate (10-50 nm) reduced the vagally evoked 5-HT signal by 50%, indicating that this release was from at least two sources. It is concluded that vagally evoked 5-HT release is under the regulation of the high-capacity, low-affinity transporter PMAT, not the low-capacity, high-affinity transporter SERT. This is the first demonstration that PMAT may be playing a physiological role in the regulation of 5-HT transmission and this could indicate that 5-HT is acting, in part, as a volume transmitter within the NTS.
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Affiliation(s)
- Patrick S Hosford
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London, WC1E 6BT, UK
| | - Julian Millar
- Department of Medical Education, Queen Mary's School of Medicine and DentistryWhitechapel, London, E1 2AD, UK
| | - Andrew G Ramage
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London, WC1E 6BT, UK
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Wang G, Erpelding N, Davis KD. Sex differences in connectivity of the subgenual anterior cingulate cortex. Pain 2014; 155:755-763. [DOI: 10.1016/j.pain.2014.01.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/23/2013] [Accepted: 01/10/2014] [Indexed: 01/08/2023]
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12
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Hosford PS, Mifflin SW, Ramage AG. 5-Hydroxytryptamine–Mediated Neurotransmission Modulates Spontaneous and Vagal-Evoked Glutamate Release in the Nucleus of the Solitary Tract Effect of Uptake Blockade. J Pharmacol Exp Ther 2014; 349:288-96. [DOI: 10.1124/jpet.113.211334] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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13
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Balaban CD, Ogburn SW, Warshafsky SG, Ahmed A, Yates BJ. Identification of neural networks that contribute to motion sickness through principal components analysis of fos labeling induced by galvanic vestibular stimulation. PLoS One 2014; 9:e86730. [PMID: 24466215 PMCID: PMC3900607 DOI: 10.1371/journal.pone.0086730] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 12/15/2013] [Indexed: 02/01/2023] Open
Abstract
Motion sickness is a complex condition that includes both overt signs (e.g., vomiting) and more covert symptoms (e.g., anxiety and foreboding). The neural pathways that mediate these signs and symptoms are yet to identified. This study mapped the distribution of c-fos protein (Fos)-like immunoreactivity elicited during a galvanic vestibular stimulation paradigm that is known to induce motion sickness in felines. A principal components analysis was used to identify networks of neurons activated during this stimulus paradigm from functional correlations between Fos labeling in different nuclei. This analysis identified five principal components (neural networks) that accounted for greater than 95% of the variance in Fos labeling. Two of the components were correlated with the severity of motion sickness symptoms, and likely participated in generating the overt signs of the condition. One of these networks included neurons in locus coeruleus, medial, inferior and lateral vestibular nuclei, lateral nucleus tractus solitarius, medial parabrachial nucleus and periaqueductal gray. The second included neurons in the superior vestibular nucleus, precerebellar nuclei, periaqueductal gray, and parabrachial nuclei, with weaker associations of raphe nuclei. Three additional components (networks) were also identified that were not correlated with the severity of motion sickness symptoms. These networks likely mediated the covert aspects of motion sickness, such as affective components. The identification of five statistically independent component networks associated with the development of motion sickness provides an opportunity to consider, in network activation dimensions, the complex progression of signs and symptoms that are precipitated in provocative environments. Similar methodology can be used to parse the neural networks that mediate other complex responses to environmental stimuli.
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Affiliation(s)
- Carey D. Balaban
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Communication Sciences and Disorders, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sarah W. Ogburn
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Susan G. Warshafsky
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Abdul Ahmed
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bill J. Yates
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Liu XH, Sun N, Du JQ, Tang JS, Han M, Zhu JX, Huo FQ. Chemical lesioning and glutamate administration reveal a major role for the nucleus tractus solitarius in the cardiac-somatic reflex in rats. Neuroscience 2012; 207:326-32. [PMID: 22326452 DOI: 10.1016/j.neuroscience.2012.01.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 01/21/2012] [Accepted: 01/23/2012] [Indexed: 12/14/2022]
Abstract
Many patients suffer from secondary muscle hyperalgesia after experiencing angina pectoris. In this study, we examined the role of the nucleus tractus solitarius (NTS) and glutamate receptors in modulating cardiac-evoked muscle hyperalgesia induced by pericardial capsaicin, which was monitored by recording electromyogram (EMG) activity from the spinotrapezius muscle in the anesthetized rat. Unilateral chemical lesioning of the commissural NTS with the neurotoxin ibotenic acid significantly depressed the cardiac-somatic reflex; the EMG responses decreased to 56.4 ± 6.9% of that of the controls (5 of 5). Microinjection of the excitatory amino acid glutamate, at 10, 20, and 50 nmol, into the commissural NTS increased the EMG response, in a dose-dependent manner, to 116.9 ± 4.9%, 143.9 ± 10.2%, and 214.2 ± 15.8% (n=8), respectively, of that of the controls. In contrast, microinjection of the N-methyl-D-aspartate (NMDA) receptor antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo [a, d]-cyclohepten-5,10-imine maleate (MK-801) at 4 and 6 nmol, decreased the EMG response to 45.2 ± 10.6% and 36.8 ± 14.3%, respectively, of that of the controls (n=8 for each dose). Similarly, the metabotropic glutamate receptor (mGluR) antagonist (RS)-a-methyl-4-carboxyphenylglycine (MCPG), at 2.5 and 5 nmol, decreased the EMG response to 65.2 ± 16.3% and 57.0 ± 4.2%, respectively, of that of the controls. When a combination of MK-801 and MCPG was administrated, the EMG response further decreased to 22.5 ± 13.2% (n=6) of that of the controls. However, administration of a non-NMDA receptor antagonist 6, 7-dinitroquinoxaline-2, 3-dione (DNQX), at 2 and 5 nmol, had no effect on the EMG response. These results suggest that the NTS is involved in the facilitation of the cardiac-somatic reflex, and that the NMDA receptor and mGluRs play an important role in mediating this effect.
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Affiliation(s)
- X-H Liu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, 76# Yanta Road W, Xi'an, Shaanxi 710061, PR China
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15
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Samuels ER, Szabadi E. Functional neuroanatomy of the noradrenergic locus coeruleus: its roles in the regulation of arousal and autonomic function part I: principles of functional organisation. Curr Neuropharmacol 2010; 6:235-53. [PMID: 19506723 PMCID: PMC2687936 DOI: 10.2174/157015908785777229] [Citation(s) in RCA: 462] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 02/25/2008] [Accepted: 06/06/2008] [Indexed: 01/09/2023] Open
Abstract
The locus coeruleus (LC) is the major noradrenergic nucleus of the brain, giving rise to fibres innervating extensive areas throughout the neuraxis. Recent advances in neuroscience have resulted in the unravelling of the neuronal circuits controlling a number of physiological functions in which the LC plays a central role. Two such functions are the regulation of arousal and autonomic activity, which are inseparably linked largely via the involvement of the LC. The LC is a major wakefulness-promoting nucleus, resulting from dense excitatory projections to the majority of the cerebral cortex, cholinergic neurones of the basal forebrain, cortically-projecting neurones of the thalamus, serotoninergic neurones of the dorsal raphe and cholinergic neurones of the pedunculopontine and laterodorsal tegmental nucleus, and substantial inhibitory projections to sleep-promoting GABAergic neurones of the basal forebrain and ventrolateral preoptic area. Activation of the LC thus results in the enhancement of alertness through the innervation of these varied nuclei. The importance of the LC in controlling autonomic function results from both direct projections to the spinal cord and projections to autonomic nuclei including the dorsal motor nucleus of the vagus, the nucleus ambiguus, the rostroventrolateral medulla, the Edinger-Westphal nucleus, the caudal raphe, the salivatory nuclei, the paraventricular nucleus, and the amygdala. LC activation produces an increase in sympathetic activity and a decrease in parasympathetic activity via these projections. Alterations in LC activity therefore result in complex patterns of neuronal activity throughout the brain, observed as changes in measures of arousal and autonomic function.
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Affiliation(s)
- E R Samuels
- Psychopharmacology Section, University of Nottingham, Division of Psychiatry, Queen's Medical Centre, Nottingham, NG7 2UH, UK
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Viisanen H, Pertovaara A. Antinociception by motor cortex stimulation in the neuropathic rat: does the locus coeruleus play a role? Exp Brain Res 2009; 201:283-96. [PMID: 19826796 DOI: 10.1007/s00221-009-2038-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 09/24/2009] [Indexed: 11/29/2022]
Abstract
We studied whether stimulation of the primary motor cortex (M1) attenuates pain-related spinal withdrawal responses of neuropathic and healthy control rats, and whether the descending antinociceptive effect is relayed through the noradrenergic locus coeruleus (LC). The assessments of the noxious heat-evoked limb withdrawals reflecting spinal nociception and recordings of single LC units were performed in spinal nerve-ligated neuropathic and sham-operated control rats under light pentobarbital anesthesia. Electric stimulation of M1 produced equally strong spinal antinociception in neuropathic and control rats. Following microinjection into M1, a group I metabotropic glutamate receptor agonist (DHPG; 10 nmol) and a high (25 nmol) but not low (2.5 nmol) dose of glutamate slightly increased on-going discharge rates of LC neurons in neuropathic but not in control animals. Influence of electric stimulation of M1 on LC neurons was studied only in the neuropathic group, in which discharge rates of LC neurons were increased by electric M1 stimulation. Lidocaine block of the LC or block of descending noradrenergic influence by intrathecal administration of a alpha(2)-adrenoceptor antagonist failed to produce a significant attenuation of the spinal antinociceptive effect induced by electric M1 stimulation in the neuropathic or the sham group. The results indicate that stimulation of the rat M1 induces spinal antinociception in neuropathic as well as control conditions. While M1 stimulation may activate the LC, particularly in the neuropathic group, the contribution of coeruleospinal noradrenergic pathways may not be critical for the spinal antinociceptive effect induced by M1 stimulation.
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Affiliation(s)
- Hanna Viisanen
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, POB 63, University of Helsinki, 00014, Helsinki, Finland
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Oskutyte D, Jordan D, Ramage AG. Evidence that 5-hydroxytryptamine(7) receptors play a role in the mediation of afferent transmission within the nucleus tractus solitarius in anaesthetized rats. Br J Pharmacol 2009; 158:1387-94. [PMID: 19785653 DOI: 10.1111/j.1476-5381.2009.00410.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Central 5-hydroxytryptamine (5-HT)-containing pathways utilizing 5-HT(7) receptors are known to be critical for the mediation of cardiovascular reflexes. The nucleus tractus solitarius (NTS) is a site involved in the integration of cardiovascular afferent information. The present experiments examined the involvement of the 5-HT(7) receptor in the processing of cardiovascular reflexes in the NTS. EXPERIMENTAL APPROACH In anaesthetized rats extracellular recordings were made from 104 NTS neurones that were excited by electrical stimulation of the vagus nerve and/or activation of cardiopulmonary afferents. Drugs were applied ionophoretically in the vicinity of these neurones. KEY RESULTS The non-selective 5-HT(7) receptor agonist 5-carboxamidotryptamine maleate (5-CT) applied to 78 neurones increased the firing rate in 18 by 59% and decreased it in 38 neurones by 47%. Similarly, the 5-HT(1A) agonist 8-OH-DPAT applied to 20 neurones had an excitatory (8), inhibitory (7) or no effect (5) on the 20 neurones tested. In the presence of the 5-HT(7) antagonist SB 258719 the 5-CT excitation was attenuated. Furthermore, the excitatory response of NTS neurones evoked by electrical stimulation of the vagus nerve or activation of cardiopulmonary afferents with intra atrial phenylbiguanide was attenuated by SB 258719. The inhibitory action of 5-CT was unaffected by SB 258719 and the 5-HT(1A) antagonist WAY-100635. WAY-100635 failed to have any effect on 5-CT and vagal afferent-evoked excitations. CONCLUSIONS AND IMPLICATIONS Vagal afferent-evoked excitation of NTS neurones can be blocked by SB 258719, a selective 5-HT(7) antagonist. This observation further supports the involvement of 5-HT neurotransmission in NTS afferent processing.
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Affiliation(s)
- Diana Oskutyte
- Research Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London, UK
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18
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Hellman KM, Mendelson SJ, Mendez-Duarte MA, Russell JL, Mason P. Opioid microinjection into raphe magnus modulates cardiorespiratory function in mice and rats. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1400-8. [PMID: 19710394 DOI: 10.1152/ajpregu.00140.2009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The raphe magnus (RM) participates in opioid analgesia and contains pain-modulatory neurons with respiration-related discharge. Here, we asked whether RM contributes to respiratory depression, the most prevalent lethal effect of opioids. To investigate whether opioidergic transmission in RM produces respiratory depression, we microinjected a mu-opioid receptor agonist, DAMGO, or morphine into the RM of awake rodents. In mice, opioid microinjection produced sustained decreases in respiratory rate (170 to 120 breaths/min), as well as heart rate (520 to 400 beats/min). Respiratory sinus arrhythmia, indicative of enhanced parasympathetic activity, was prevalent in mice receiving DAMGO microinjection. We performed similar experiments in rats but observed no changes in breathing rate or heart rate. Both rats and mice experienced significantly more episodes of bradypnea, indicative of impaired respiratory drive, after opioid microinjection. During spontaneous arousals, rats showed less tachycardia after opioid microinjection than before microinjection, suggestive of an attenuated sympathetic tone. Thus, activation of opioidergic signaling within RM produces effects beyond analgesia, including the unwanted destabilization of cardiorespiratory function. These adverse effects on homeostasis consequent to opioid microinjection imply a role for RM in regulating the balance of sympathetic and parasympathetic tone.
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Affiliation(s)
- Kevin M Hellman
- Department of Neurobiology and 2Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637, USA
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Tillu DV, Gebhart GF, Sluka KA. Descending facilitatory pathways from the RVM initiate and maintain bilateral hyperalgesia after muscle insult. Pain 2008; 136:331-339. [PMID: 17764841 PMCID: PMC2519171 DOI: 10.1016/j.pain.2007.07.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 06/27/2007] [Accepted: 07/17/2007] [Indexed: 11/19/2022]
Abstract
The rostral ventromedial medulla (RVM) is involved in facilitation of spinal nociceptive processing and generation of hyperalgesia in inflammatory and neuropathic pain models. We hypothesized that the bilateral hyperalgesia that develops after repeated intramuscular injections of acidic saline is initiated and maintained by activation of descending facilitatory pathways from the RVM. Male Sprague-Dawley rats were implanted with intracerebral guide cannulae into the nucleus raphe magnus (NRM) or the nucleus gigantocellularis (Gi). Two injections of acidic saline into one gastrocnemius muscle 5 days apart lead to robust hyperalgesia after the second injection. Either ropivacaine (local anesthetic) or vehicle (control) was microinjected into the RVM prior to the first intramuscular acid injection, prior to the second injection, or 24h after the second injection. Mechanical withdrawal thresholds of the paw (von Frey filaments) and the muscle (tweezer) were measured before and 24h after induction of hyperalgesia. The withdrawal thresholds for both the paw (cutaneous secondary hyperalgesia) and muscle (primary hyperalgesia) were decreased 24h after the second intramuscular acid injection in the vehicle control groups. Administration of ropivacaine prior to the first intramuscular acid injection had no effect on development of either cutaneous or muscle hyperalgesia that develops after the second injection. However, neither cutaneous nor muscle hyperalgesia developed in the group treated with ropivacaine prior to the second intramuscular injection. Ropivacaine also significantly reversed the hyperalgesia in the group treated 24h after the second intramuscular acid injection. Thus, the RVM is critical for both the development and maintenance of hyperalgesia after muscle insult.
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Affiliation(s)
- D V Tillu
- Graduate Program in Physical Therapy and Rehabilitation Science, Pain Research Program, University of Iowa, Iowa City, IA 52242, USA Pittsburgh Center for Pain Research, Departments of Anesthesiology, Neurobiology and Pharmacology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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20
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Brown JW, Sirlin EA, Benoit AM, Hoffman JM, Darnall RA. Activation of 5-HT1A receptors in medullary raphé disrupts sleep and decreases shivering during cooling in the conscious piglet. Am J Physiol Regul Integr Comp Physiol 2008; 294:R884-94. [DOI: 10.1152/ajpregu.00655.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of 5-HT1A receptors in the medullary raphé decreases sympathetically mediated brown adipose tissue (BAT) thermogenesis and peripheral vasoconstriction when previously activated with leptin, LPS, prostaglandins, or cooling. It is not known whether shivering is also modulated by medullary raphé 5-HT1A receptors. We previously showed in conscious piglets that activation of 5-HT1A receptors with (±)-8-hydroxy-2-(dipropylamino)-tetralin (8-OH-DPAT) in the paragigantocellularis lateralis (PGCL), a medullary region lateral to the raphé that contains substantial numbers of 5-HT neurons, eliminates rapid eye movement (REM) sleep and decreases shivering in a cold environment, but does not attenuate peripheral vasoconstriction. Hoffman JM, Brown JW, Sirlin EA, Benoit AM, Gill WH, Harris MB, Darnall RA. Am J Physiol Regul Integr Comp Physiol 293: R518–R527, 2007. We hypothesized that, during cooling, activation of 5-HT1A receptors in the medullary raphé would also eliminate REM sleep and, in contrast to activation of 5-HT1A receptors in the PGCL, would attenuate both shivering and peripheral vasoconstriction. In a continuously cool environment, dialysis of 8-OH-DPAT into the medullary raphé resulted in alternating brief periods of non-REM sleep and wakefulness and eliminated REM sleep, as observed when 8-OH-DPAT is dialyzed into the PGCL. Moreover, both shivering and peripheral vasoconstriction were significantly attenuated after 8-OH-DPAT dialysis into the medullary raphé. The effects of 8-OH-DPAT were prevented after dialysis of the selective 5-HT1A receptor antagonist WAY-100635. We conclude that, during cooling, exogenous activation of 5-HT1A receptors in the medullary raphé decreases both shivering and peripheral vasoconstriction. Our data are consistent with the hypothesis that neurons expressing 5-HT1A receptors in the medullary raphé facilitate spinal motor circuits involved in shivering, as well as sympathetic stimulation of other thermoregulatory effector mechanisms.
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21
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Pinto-Ribeiro F, Ansah OB, Almeida A, Pertovaara A. Influence of arthritis on descending modulation of nociception from the paraventricular nucleus of the hypothalamus. Brain Res 2008; 1197:63-75. [DOI: 10.1016/j.brainres.2007.12.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 12/12/2007] [Accepted: 12/12/2007] [Indexed: 01/22/2023]
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Governo RJM, Prior MJW, Morris PG, Marsden CA, Chapman V. Validation of an automated punctate mechanical stimuli delivery system designed for fMRI studies in rodents. J Neurosci Methods 2007; 163:31-7. [PMID: 17368787 DOI: 10.1016/j.jneumeth.2007.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 02/11/2007] [Indexed: 10/23/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is increasingly being used for animal studies studying the transmission of nociceptive information. Application of noxious mechanical stimuli is widely used for animal and human assessment of pain processing. Any accessory hardware used in animal imaging studies must, however, be sufficiently small to fit in the magnet bore diameter and be non-magnetic. We have developed a system that can apply mechanical stimuli simultaneously with fMRI. This system consists of a standardized instrument to deliver mechanical stimuli (VonFrey monofilament) and a gas-pressured mechanical transducer. These components were integrated with a computer console that controlled the period of stimuli to match acquisition scans. Preliminary experiments demonstrated that the force-stimulus transducer did not influence MRI signal to noise ratio. Mechanical stimulation of the hindpaw significantly increased blood oxygen level dependent (BOLD) signal intensity in several midbrain regions involved in the processing of nociceptive information in the rat (p<0.001, uncorrected for multiple comparisons). This system can be applied to both animal and human imaging studies and has a wide range of applications for studies of nociceptive processing.
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da Silva LFS, Menescal-de-Oliveira L. Role of opioidergic and GABAergic neurotransmission of the nucleus raphe magnus in the modulation of tonic immobility in guinea pigs. Brain Res Bull 2007; 72:25-31. [PMID: 17303504 DOI: 10.1016/j.brainresbull.2006.12.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2006] [Revised: 12/06/2006] [Accepted: 12/13/2006] [Indexed: 11/19/2022]
Abstract
Tonic immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. Previous results from our laboratory have demonstrated that nucleus raphe magnus (NRM) is also a structure involved in the modulation of TI behavior, as chemical stimulation through carbachol decreases the duration of TI in guinea pigs. In view of the fact that GABAergic and opioidergic circuits participate in the regulation of neuronal activity in the NRM and since these neurotransmitters are also involved in the modulation of TI, the objective of the present study was to evaluate the role of these circuits of the NRM in the modulation of the behavioral TI response. Microinjection of morphine (4.4 nmol/0.2 microl) or bicuculline (0.4 nmol/0.2 microl) into the NRM increased the duration of TI episodes while muscimol (0.5 nmol/0.2 microl) decreased it. The effect of morphine injection into the NRM was blocked by previous microinjection of naloxone (2.7 nmol/0.2 microl). Muscimol at 0.25 nmol did not produce any change in TI duration; however, it blocked the increased response induced by morphine. Our results indicate a facilitatory role of opioidergic neurotransmission in the modulation of the TI response within the NRM, whereas GABAergic activity plays an inhibitory role. In addition, in the present study the modulation of TI in the NRM possibly occurred via an interaction between opioidergic and GABAergic systems, where the opioidergic effect might be due to inhibition of tonically active GABAergic interneurons.
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Affiliation(s)
- Luis Felipe Souza da Silva
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, 14049-900 Ribeirão Preto, SP, Brazil
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24
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Pertovaara A. Noradrenergic pain modulation. Prog Neurobiol 2006; 80:53-83. [PMID: 17030082 DOI: 10.1016/j.pneurobio.2006.08.001] [Citation(s) in RCA: 390] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 08/25/2006] [Accepted: 08/30/2006] [Indexed: 11/18/2022]
Abstract
Norepinephrine is involved in intrinsic control of pain. Main sources of norepinephrine are sympathetic nerves peripherally and noradrenergic brainstem nuclei A1-A7 centrally. Peripheral norepinephrine has little influence on pain in healthy tissues, whereas in injured tissues it has variable effects, including aggravation of pain. Its peripheral pronociceptive effect has been associated with injury-induced expression of novel noradrenergic receptors, sprouting of sympathetic nerve fibers, and pronociceptive changes in the ionic channel properties of primary afferent nociceptors, while an interaction with the immune system may contribute in part to peripheral antinociception induced by norepinephrine. In the spinal cord, norepinephrine released from descending pathways suppresses pain by inhibitory action on alpha-2A-adrenoceptors on central terminals of primary afferent nociceptors (presynaptic inhibition), by direct alpha-2-adrenergic action on pain-relay neurons (postsynaptic inhibition), and by alpha-1-adrenoceptor-mediated activation of inhibitory interneurons. Additionally, alpha-2C-adrenoceptors on axon terminals of excitatory interneurons of the spinal dorsal horn possibly contribute to spinal control of pain. At supraspinal levels, the pain modulatory effect by norepinephrine and noradrenergic receptors has varied depending on many factors such as the supraspinal site, the type of the adrenoceptor, the duration of the pain and pathophysiological condition. While in baseline conditions the noradrenergic system may have little effect, sustained pain induces noradrenergic feedback inhibition of pain. Noradrenergic systems may also contribute to top-down control of pain, such as induced by a change in the behavioral state. Following injury or inflammation, the central as well as peripheral noradrenergic system is subject to various plastic changes that influence its antinociceptive efficacy.
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Affiliation(s)
- Antti Pertovaara
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, PO Box 63, University of Helsinki, FIN-00014 Helsinki, Finland.
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25
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Taylor NC, Li A, Nattie EE. Ventilatory effects of muscimol microdialysis into the rostral medullary raphé region of conscious rats. Respir Physiol Neurobiol 2006; 153:203-16. [PMID: 16338178 DOI: 10.1016/j.resp.2005.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 11/08/2005] [Accepted: 11/08/2005] [Indexed: 11/26/2022]
Abstract
We hypothesized that inhibition of the rostral medullary raphe region (MRR), a putative central chemoreceptor location, with the GABA(A) receptor agonist muscimol would decrease ventilatory responses to hypercapnia and hypoxia in conscious rats, and that its known effect at this site on body temperature might alter its effect upon these ventilatory responses. At ambient temperatures of 24.5-26.5 degrees C (Cool), microdialysis of 1mM muscimol into the MRR significantly decreased body temperature by approximately 0.5 degrees C, increased the ventilatory response to 7% CO(2) and decreased the response to 10% O(2). At ambient temperatures of 29.5-30.5 degrees C (Warm), 1 mM muscimol microdialysis no longer decreased body temperature and increased the ventilatory response to hypercapnia and to hypoxia. Muscimol did not significantly affect the VE/VO2 ratio at either temperature. Muscimol significantly increased the hypercapnic ventilatory responses in Cool and Warm conditions and the hypoxic response in Warm conditions, which indicates the presence of an inhibitory effect of rostral MRR neurons sensitive to muscimol. In the Cool condition the ventilatory response to hypoxia is inhibited but appropriately so for the lower VO2 .
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Affiliation(s)
- Natalie C Taylor
- Department of Physiology, Dartmouth-Hitchcock Medical Center, Borwell Bldg., Lebanon, NH 03756-0001, USA
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Wei H, Pertovaara A. 5-HT1A receptors in endogenous regulation of neuropathic hypersensitivity in the rat. Eur J Pharmacol 2006; 535:157-65. [PMID: 16545367 DOI: 10.1016/j.ejphar.2006.02.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 02/09/2006] [Accepted: 02/13/2006] [Indexed: 11/28/2022]
Abstract
The role of medullary and spinal 5-HT(1A) receptors in endogenous regulation of neuropathic hypersensitivity was studied. When administered in the rostroventromedial medulla or subcutaneously, WAY-100635, a 5-HT(1A) receptor antagonist, attenuated mechanical hypersensitivity in rats with a spinal nerve injury. Thermal or mechanical nociception outside of the injured area was not influenced by medial medullary or subcutaneous administration of WAY-100635. Intrathecal administration of WAY-100635 had no significant effect on pain-related behavior. Suppression of mechanical hypersensitivity induced by medial medullary administration of WAY-100635 was reversed by intrathecal administration of WAY-100635 or atipamezole, an alpha2-adrenoceptor antagonist, but not by naloxone, an opioid receptor antagonist. The results indicate that endogenous release of 5-HT, via action on medial medullary 5-HT(1A) receptors, tonically suppresses descending inhibition in neuropathic animals. Following medial medullary administration of a 5-HT(1A) receptor antagonist, descending pain regulatory pathways are disinhibited. This leads to selective attenuation of neuropathic hypersensitivity, due to action on spinal 5-HT(1A) receptors and alpha2-adrenoceptors.
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Affiliation(s)
- Hong Wei
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, POB 63, 00014 University of Helsinki, Finland
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Kishi R, Bongiovanni R, de Nadai TR, Freitas RL, de Oliveira R, Ferreira CMDR, Coimbra NC. Dorsal raphe nucleus and locus coeruleus neural networks and the elaboration of the sweet-substance-induced antinociception. Neurosci Lett 2006; 395:12-7. [PMID: 16289556 DOI: 10.1016/j.neulet.2005.10.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 09/16/2005] [Accepted: 10/17/2005] [Indexed: 11/26/2022]
Abstract
In order to investigate the effects of monoaminergic neurons of the dorsal raphe nucleus (DRN) and locus coeruleus (LC) on the elaboration and control of sweet-substance-induced antinociception, male albino Wistar rats weighing 180-200 g received sucrose solution (250 g/L) for 7-14 days as their only source of liquid. After the chronic consumption of sucrose solution, each animal was pretreated with unilateral microinjection of ibotenic acid (1.0 microg/0.2 microL) in the DRN or in the LC. The tail withdrawal latencies of the rats in the tail-flick test were measured immediately before and 7 days after this treatment. The neurochemical lesion of locus coeruleus, but not of DRN neural networks with ibotenic acid, after the chronic intake of sweetened solution, decreased the sweet-substance-induced antinociception. These results indicate the involvement of noradrenaline-containing neurons of the LC in the sucrose-induced antinociception. We also consider the possibility of DRN serotonergic neurons exerting some inhibitory effect on the LC neural networks involved with the elaboration of the sweet-substance-induced antinociception.
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Affiliation(s)
- Renato Kishi
- Laboratório de Neuroanatomia e Neuropsicobiologia, Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP-USP), Avenida dos Bandeirantes, 3900 Ribeirão Preto (SP) 14049-900, Brasil
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Pertovaara A, Almeida A. Chapter 13 Descending inhibitory systems. HANDBOOK OF CLINICAL NEUROLOGY 2006; 81:179-192. [PMID: 18808835 DOI: 10.1016/s0072-9752(06)80017-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Zhang L, Sykes KT, Buhler AV, Hammond DL. Electrophysiological heterogeneity of spinally projecting serotonergic and nonserotonergic neurons in the rostral ventromedial medulla. J Neurophysiol 2005; 95:1853-63. [PMID: 16338998 DOI: 10.1152/jn.00883.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study examined the passive membrane and action potential properties of serotonergic and nonserotonergic neurons in the rostral ventromedial medulla (RVM) of the rat using whole cell patch-clamp recording techniques in the slice. Serotonergic neurons were identified by immunoreactivity for tryptophan hydroxylase (TrpH). Spinally projecting neurons were retrogradely labeled with 1'-dioactadecyl-3,3,3',3'-tetramethylindocarbodyanine perchlorate (DiI). Three types of neurons were identified within both spinally projecting serotonergic and nonserotonergic populations. Type 1 neurons exhibited irregular or sporadic spontaneous activity interspersed with periods of quiescence. Type 2 neurons were not spontaneously active and were additionally discriminated by a more negative resting membrane potential and a larger-amplitude action potential. Type 3 neurons fired repetitively without pause. Serotonergic neurons had a higher membrane resistance and greater action potential half-width than their nonserotonergic counterparts and rarely exhibited a fast afterhyperpolarization. Serotonergic type 3 neurons also fired more slowly and regularly than nonserotonergic type 3 neurons. Comparison of electrophysiological and immunohistochemical characteristics suggested that the smallest type 3 serotonergic neurons had an increased risk of immunohistochemical "misclassification" due to failure to detect TrpH, possibly due to more complete dialysis of intracellular contents during lengthy recordings. This risk was minimal for type 1 or 2 serotonergic neurons. The three different types of spinally projecting serotonergic neurons also differed markedly in their responsiveness to the mu opioid receptor agonist D-Ala2, NMePhe4, Gly5-ol]enkephalin. These results provide important new electrophysiological and pharmacological evidence for a significant heterogeneity among spinally projecting serotonergic RVM neurons. They may also provide a basis for resolving the controversy concerning the role of serotonergic RVM neurons in opioid analgesia.
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Affiliation(s)
- Liang Zhang
- Dept. of Anesthesia, University of Iowa, 200 Hawkins Dr., 6 JCP, Iowa City, IA 52242, USA
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Gamboa-Esteves FO, Tavares I, Almeida A, Batten TF, McWilliam PN, Lima D. Projection sites of superficial and deep spinal dorsal horn cells in the nucleus tractus solitarii of the rat. Brain Res 2001; 921:195-205. [PMID: 11720726 DOI: 10.1016/s0006-8993(01)03118-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
By using anterograde transport of biotin dextran amine injected into the cervical spinal dorsal horn, we have shown that fibres from superficial and deep dorsal horn project to the nucleus tractus solitarii via two distinct pathways. Afferent fibres from the superficial lamina (I-III) were found to course in the dorsal funiculus and terminate bilaterally in the caudal zone of the nucleus tractus solitarii (NTS), mainly within the commissural subnucleus. In contrast, afferents from the deeper dorsal horn laminae (IV-V) were found to course in the dorsolateral fasciculus and terminate ipsilaterally, mostly in the lateral areas of the caudal nucleus tractus solitarii. Similar, but more extensive patterns of labelled fibres were produced by injections into the white matter of the dorsal funiculus and dorsolateral fasciculus, respectively. These observations suggest that the caudal NTS not only serves as a location of visceral afferent convergence and integration, but may also be a receptive area for monosynaptic projections from dorsal horn neurons receiving sensory afferent inputs. Such projections may represent pathways through which NTS neurons are influenced by nociceptive and non-nociceptive information from the dorsal horn and thereby can co-ordinate the appropriate autonomic response, including adjustments in cardiorespiratory reflex output.
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Affiliation(s)
- F O Gamboa-Esteves
- Institute for Cardiovascular Research, School of Medicine, Worsley Building, University of Leeds, Leeds LS2 9JT, UK
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31
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Grabow TS, Hurley RW, Banfor PN, Hammond DL. Supraspinal and spinal delta(2) opioid receptor-mediated antinociceptive synergy is mediated by spinal alpha(2) adrenoceptors. Pain 1999; 83:47-55. [PMID: 10506671 DOI: 10.1016/s0304-3959(99)00084-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Concurrent administration of low doses of [D-Ala(2), Glu(4)]deltorphin (DELT) in the spinal cord and rostral ventromedial medulla of the rat produces a synergistic antinociception in the tail-flick test. It was postulated that the synergistic antinociception results from an interaction of the intrathecally-administered DELT with norepinephrine released in the spinal cord as a result of the microinjection of DELT in the rostral ventromedial medulla. Three approaches were taken to test this hypothesis. The first experiment determined that microinjection of DELT in the rostral ventromedial medulla produced an increase in tail-flick latency that was partially attenuated by intrathecal administration of the alpha(2)-adrenoceptor antagonist yohimbine. These data indicated that microinjection of DELT in the medulla causes a release of norepinephrine in the spinal cord. The second experiment determined that intrathecal co-administration of DELT with the alpha(2)-adrenoceptor agonist dexmedetomidine in a 2:1 fixed dose ratio produced a synergistic antinociception in the tail-flick test. The final experiment determined that the antinociception produced by concurrent medullary and intrathecal administration of DELT was completely antagonized by intrathecal administration of yohimbine. Taken together, these findings support the hypothesis that the synergistic antinociception produced by concurrent activation of medullary and spinal delta(2) opioid receptors is mediated, in part, by endogenous norepinephrine release in the spinal cord. The norepinephrine, acting at alpha(2)-adrenoceptors, interacts in a synergistic manner with intrathecally administered DELT, acting at spinal delta(2) opioid receptors, to produce antinociception.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/pharmacology
- Anesthesia, Spinal
- Animals
- Dexmedetomidine/pharmacology
- Drug Synergism
- Injections, Spinal
- Male
- Nociceptors/drug effects
- Nociceptors/physiology
- Norepinephrine/pharmacology
- Norepinephrine/physiology
- Oligopeptides/administration & dosage
- Oligopeptides/pharmacology
- Pain Measurement
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/physiology
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, delta/physiology
- Spinal Cord/drug effects
- Spinal Cord/physiology
- Yohimbine/pharmacology
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Affiliation(s)
- T S Grabow
- Department of Anesthesiology and Critical Care, University of Chicago, 5841 South Maryland Avenue M/C 4028, Chicago, USA
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Morin LP, Meyer-Bernstein EL. The ascending serotonergic system in the hamster: comparison with projections of the dorsal and median raphe nuclei. Neuroscience 1999; 91:81-105. [PMID: 10336062 DOI: 10.1016/s0306-4522(98)00585-5] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ascending serotonergic projections are derived largely from the midbrain median and dorsal raphe nuclei, and contribute to the regulation of many behavioral and physiological systems. Serotonergic innervation of the hamster circadian system has been shown to be substantially different from earlier results obtained with other methods and species. The present study was conducted to determine whether similar differences are observed in other brain regions. Ascending projections from the hamster dorsal or median raphe were identified using an anterograde tracer, Phaseolus vulgans leucoagglutinin, injected by iontophoresis into each nucleus. Brains were processed for tracer immunoreactivity, and drawings were made of the median raphe and dorsal raphe efferent projection patterns. The efferents were also compared to the distribution of normal serotonergic innervation of the hamster midbrain and forebrain. The results show widespread, overlapping projection patterns from both the median and dorsal raphe, with innervation generally greater from the dorsal raphe. In several brain regions, including parts of the pretectum, lateral geniculate and basal forebrain, nuclei are innervated by the dorsal, but not the median, raphe. The hypothalamic suprachiasmatic nucleus is the only site innervated exclusively by the median and not by the dorsal raphe. The pattern of normal serotonin fiber and terminal distribution is generally more robust than would be inferred from the anterograde tracer material. However, there is good qualitative similarity between the two sets of data. The oculomotor nucleus and the medial habenula are unusual to the extent that each has a moderately dense serotonin terminal plexus, although neither receives innervation from the median or dorsal raphe. In contrast, the centrolateral thalamic nucleus and lateral habenula have little serotonergic innervation, but receive substantial other neural input from the raphe nuclei. The normal serotonergic innervation of the hamster brain is similar to that in the rat, although there are exceptions. The anterograde tracing of ascending median or dorsal raphe projections reveals a high, but imperfect, degree of correspondence with the serotonin innervation data, and with data from rats derived from immunohistochemical and autoradiographic tract-tracing techniques.
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Affiliation(s)
- L P Morin
- Department of Psychiatry, Stony Brook University, NY 11794, USA
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Bernard DG. Cardiorespiratory responses to glutamate microinjected into the medullary raphé. RESPIRATION PHYSIOLOGY 1998; 113:11-21. [PMID: 9776546 DOI: 10.1016/s0034-5687(98)00050-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The involvement of the medullary raphé in modulating cardiorespiratory activity was examined by microinjecting L-glutamate (L-Glu) into the raphé of rats. Animals were vagotomized, paralyzed, artificially ventilated, maintained at 37 degrees C, and instrumented to record arterial blood pressure (BP) and phrenic nerve activity (PNA). Mock cerebrospinal fluid (mCSF, 10 nl, pH 7.4; control) and L-Glu dissolved in mCSF (10, 100, 1000 mM; 10 nl; pH 7.4; experimental) were microinjected into the raphé. L-Glu affected both BP and PNA in a dose dependent manner. Blood pressure was reduced by 6.30 +/- 0.97 and 12.98 +/- 1.29% by 100 and 1000 mM L-Glu, respectively, without affecting heart rate. PNA increased by 23 and 38% with 100 and 1000 mM L-Glu, respectively. Mock CSF and 10 mM L-Glu had no effect. It is concluded that there are sites in the medullary raphé that affect blood pressure only and other sites which can affect both blood pressure and respiration.
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Affiliation(s)
- D G Bernard
- Department of Biology, University of Texas at Arlington, 76019, USA.
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Holden JE, Proudfit HK. Enkephalin neurons that project to the A7 catecholamine cell group are located in nuclei that modulate nociception: ventromedial medulla. Neuroscience 1998; 83:929-47. [PMID: 9483575 DOI: 10.1016/s0306-4522(97)00437-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The location of methionine enkephalin neurons in the medulla oblongata that project to the dorsolateral pontine tegmentum was investigated using anterograde and retrograde tract tracing combined with immunocytochemical neurotransmitter identification. The results of these experiments demonstrate that enkephalinergic neurons from areas known to modulate nociception project to the region of the A7 catecholamine cell group in the dorsolateral pontine tegmentum. The medullary nuclei that contain these enkephalinergic neurons include the nucleus raphe magnus and the nucleus reticularis gigantocellularis pars alpha in the ventromedial medulla. While some of these enkephalinergic axons appose the somata and dendrites of A7 neurons, the majority of these axons appear to contact non-catecholamine neurons in the dorsolateral pontine tegmentum. Unidentified neurons located in the nucleus raphe magnus, the nucleus reticularis gigantocellularis pars alpha, and the nucleus reticularis gigantocellularis also project to the A7 area. Many of the neurons in the nucleus reticularis gigantocellularis pars alpha appear to contact both noradrenergic A7 neurons and non-catecholamine neurons in the dorsolateral pontine tegmentum, whereas most of those in the nucleus raphe magnus appear to contact non-catecholamine neurons. The anatomical findings described in this report and the results of preliminary behavioral studies provide evidence to support a model in which activation of the enkephalin-containing neurons in the ventromedial medulla facilitates nociception, while the non-enkephalin neurons mediate part of the antinociception produced by stimulating sites in the ventromedial medulla.
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Affiliation(s)
- J E Holden
- Department of Pharmacology, University of Illinois at Chicago 60612, USA
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35
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Wiertelak EP, Roemer B, Maier SF, Watkins LR. Comparison of the effects of nucleus tractus solitarius and ventral medial medulla lesions on illness-induced and subcutaneous formalin-induced hyperalgesias. Brain Res 1997; 748:143-50. [PMID: 9067455 DOI: 10.1016/s0006-8993(96)01289-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have previously demonstrated that illness-inducing agents (lipopolysaccharide (LPS)) and inflammatory agents (subcutaneous (s.c.) formalin) induce hyperalgesia by similar pathways. The present series of experiments compared the effects of medullary lesions on these phenomena. These experiments demonstrate that s.c. formalin-induced hyperalgesia, like illness-induced hyperalgesia, is dependent on the nucleus raphe magnus (NRM) but independent of the nucleus reticularis paragigantocellularis (NRPgc). However, these two forms of hyperalgesia differ with regards to their dependence on the nucleus tractus solitarius (NTS). Illness-induced hyperalgesia is abolished by unilateral (left) NTS lesions, whereas formalin-induced hyperalgesia remains unaffected by this procedure. These data provide further evidence that hyperalgesias induced by illness agents and by inflammatory agents are mediated by similar but not identical pathways. They also illustrate that neural structures have the capacity for opposed actions, in that both the NTS and NRM are documented to underlie hyperalgesia as well as analgesia. This capacity for opposed action may prove to be characteristic of structures involved in pain modulation.
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Affiliation(s)
- E P Wiertelak
- Department of Psychology, Macalester College, St. Paul, MN 55105, USA.
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Abstract
The major functions of the midbrain periaqueductal gray (PAG), including pain and analgesia, fear and anxiety, vocalization, lordosis and cardiovascular control are considered in this review article. The PAG is an important site in ascending pain transmission. It receives afferents from nociceptive neurons in the spinal cord and sends projections to thalamic nuclei that process nociception. The PAG is also a major component of a descending pain inhibitory system. Activation of this system inhibits nociceptive neurons in the dorsal horn of the sinal cord. The dorsal PAG is a major site for processing of fear and anxiety. It interacts with the amygdala and its lesion alters fear and anxiety produced by stimulation of amygdala. Stimulation of PAG produces vocalization and its lesion produces mutism. The firing of many cells within the PAG correlates with vocalization. The PAG is a major site for lordosis and this role of PAG is mediated by a pathway connecting the medial preoptic with the PAG. The cardiovascular controlling network within the PAG are organized in columns. The dorsal column is involved in pressor and the ventrolateral column mediates depressor responses. The major intrinsic circuit within the PAG is a tonically-active GABAergic network and inhibition of this network is an important mechanism for activation of outputs of the PAG. The various functions of the PAG are interrelated and there is a significant interaction between different functional components of the PAG. Using the current information about the anatomy, physiology, and pharmacology of the PAG, a model is proposed to account for the interactions between these different functional components.
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Affiliation(s)
- M M Behbehani
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, OH 45267-0576, USA
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37
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Murphy AZ, Behbehani MM. Role of norepinephrine in the interaction between the lateral reticular nucleus and the nucleus raphe magnus: an electrophysiological and behavioral study. Pain 1993; 55:183-193. [PMID: 8309708 DOI: 10.1016/0304-3959(93)90147-h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have previously demonstrated that the nucleus raphe magnus (NRM) sends a predominantly inhibitory projection to the lateral reticular nucleus (LRN); however, the pharmacology of this pathway is not known. The purpose of this study was to examine the role of norepinephrine in the NRM-LRN system using both electrophysiological and behavioral techniques. Sixty-nine LRN cells were recorded extracellularly. Cells were tested for their response to noxious and innocuous peripheral stimulation applied to the dorsal body surface. The majority of cells were classified as wide dynamic range, with inhibition being the predominant response; receptive fields were located primarily on the tail and hind limbs. The effect of excitatory amino acid glutamate (GLU) administration into NRM (GLU-NRM) was tested on all 69 cells. GLU-NRM inhibited 55 of 69 LRN cells tested; 7 cells were excited and 7 cells did not respond. Thirty-nine LRN cells were tested for their response to norepinephrine (NE) iontophoretically applied in LRN (NE-LRN). Two distinct types of effects were noted. In 9 cells, both NE-LRN and GLU-NRM produced a strong inhibition, with the magnitude of effect between the 2 drugs significantly correlated. In a second group of cells (n = 12), GLU-NRM produced an inhibitory effect while NE-LRN had no effect on the cells' baseline firing rate. However, when the 2 drugs were applied simultaneously, NE-LRN blocked the inhibitory effects of NRM stimulation. The effect of the alpha 2-receptor antagonist yohimbine (YOH) on NRM-evoked responses was tested in 30 LRN cells. The majority of these cells were inhibited by GLU-NRM. Similar to the dichotomous effect noted by NE-LRN, YOH applied iontophoretically in LRN (YOH-LRN) had two predominant effects on NRM-produced inhibition. In 14 of 27 cells, YOH-LRN significantly potentiated the inhibitory effects of NRM stimulation by increasing the duration of the inhibitory epoch an average of 100 sec. In 7 of 27 cells, YOH directly applied in LRN partially antagonized NRM-evoked inhibition. In a second series of experiments, microinjection cannulas were placed within NRM and LRN in order to determine the effect of blocking alpha 2-receptor activity within LRN on NRM stimulation-produced analgesia in an intact animal. Administration of D,L-homocysteic acid in NRM resulted in a significant increase in baseline tail-flick latency of approximately 140%. Pretreatment with YOH (3 micrograms in 0.5 microliter) in LRN resulted in a significant potentiation of this analgesic effect.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- Anne Z Murphy
- Department of Physiology and Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267 USA
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