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Netzer F, Sévoz-Couche C. Rostral cuneiform nucleus and the defence reaction: Direct and indirect midbrain-medullary 5-HT mechanisms in baroreflex inhibition. Br J Pharmacol 2021; 178:1819-1835. [PMID: 33543768 DOI: 10.1111/bph.15406] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/18/2020] [Accepted: 01/23/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Activation of the defence reaction inhibits the baroreflex response via the intermediate rostro-ventromedial medulla (B3 raphé) and nucleus tractus solitarius (NTS). Our aim was to determine whether and how baroreflex inhibition, induced by the disinhibition of the rostral cuneiform nucleus (part of the defence pathway), involves 5-HT neurons in B3 and 5-HT3 receptors in the NTS. EXPERIMENTAL APPROACH We performed immunohistochemistry and anatomical experiments to determine whether raphé 5-HT cells expressing Fos were directly targeted by the rostral cuneiform nucleus. The effect of blocking raphé 5-HT neurotransmission and NTS 5-HT3 receptors on cuneiform-induced inhibition of the baroreflex cardiac response were also analysed. KEY RESULTS Bicuculline, microinjected into the rostral cuneiform nucleus, induced an increase of double-labelled Fos-5-HT-IR cells in both the lateral paragigantocellular nucleus (LPGi) and raphé magnus. The anterograde tracer Phaseolus vulgaris leucoaggutinin injected into the rostral cuneiform nucleus revealed a dense projection to the LPGi but not raphé magnus. Cuneiform-induced baroreflex inhibition was prevented by B3 injection of 8-OH-DPAT, a selective 5-HT1A receptor agonist. Cuneiform disinhibition also failed to inhibit the baroreflex bradycardia after NTS microinjection of the 5-HT3 receptor antagonist granisetron and in 5-HT3 receptor knockout mice. CONCLUSION AND IMPLICATIONS The rostral cuneiform nucleus participates in the defence inhibition of the baroreflex bradycardia via direct activation of the LPGi and via a projection to the raphé magnus to activate NTS 5-HT3 receptors and inhibit second-order baroreflex neurons. These data bring new insights in primary and secondary mechanisms involved in vital baroreflex prevention during stress.
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Affiliation(s)
- Florence Netzer
- INSERM U894, Centre of Psychiatry and Neurosciences, Paris, France
| | - Caroline Sévoz-Couche
- Sorbonne Université, INSERM, UMRS1158, Neurophysiologie Respiratoire, Expérimentale et Clinique, Paris, France
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A hypothalamo-midbrain-medullary pathway involved in the inhibition of the respiratory chemoreflex response induced by potassium cyanide in rodents. Neuropharmacology 2017; 128:152-167. [PMID: 28987939 DOI: 10.1016/j.neuropharm.2017.09.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/07/2017] [Accepted: 09/26/2017] [Indexed: 01/05/2023]
Abstract
Recent studies have demonstrated that a mild stimulation of the dorsomedian nucleus of the hypothalamus (DMH), a defense area, induces the inhibition of the carotid chemoreflex tachypnea. DMH activation reduces the cardiac chemoreflex response via the dorsolateral part of the periaqueductal grey matter (dlPAG) and serotonin receptors (5-HT3 subtype) in the nucleus tractus solitarius (NTS). The objectives of this study were to assess whether dlPAG and subsequent NTS 5-HT3 receptors are involved in chemoreflex tachypnea inhibition during mild activation of the DMH. For this purpose, peripheral chemoreflex was activated with potassium cyanide (KCN, 40 μg/rat, i.v.) during electrical and chemical minimal supra-threshold (mild) stimulation of the dlPAG or DMH. In both situations, changes in respiratory frequency (RF) following KCN administration were reduced. Moreover, pharmacological blockade of the dlPAG prevented DMH-induced KCN tachypnea inhibition. Activation of NTS 5-HT3 receptors also reduced chemoreflex tachypnea in a dose-dependent manner. In addition, blockade of NTS 5-HT3 receptors with granisetron (2.5 but not 1.25 mM), or the use of mice lacking the 5-HT3a receptor (5-HT3a KO), prevented dlPAG-induced KCN reductions in RF. A respiratory hypothalamo-midbrain-medullary pathway (HMM) therefore plays a crucial role in the inhibition of the hyperventilatory response to carotid chemoreflex.
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Brouillard C, Carrive P, Camus F, Bénoliel JJ, Similowski T, Sévoz-Couche C. Long-lasting bradypnea induced by repeated social defeat. Am J Physiol Regul Integr Comp Physiol 2016; 311:R352-64. [DOI: 10.1152/ajpregu.00021.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/18/2016] [Indexed: 12/17/2022]
Abstract
Repeated social defeat in the rat induces long-lasting cardiovascular changes associated with anxiety. In this study, we investigated the effects of repeated social defeat on breathing. Respiratory rate was extracted from the respiratory sinus arrhythmia (RSA) peak frequency of the ECG in rats subjected to social defeat for 4 consecutive days. Respiratory rate was recorded under anesthesia 6 days (D+10) or 26 days (D+30) after social defeat. At D+10, defeated (D) rats spent less time in the open arms of the elevated plus maze test, had heavier adrenal glands, and displayed bradypnea, unlike nondefeated animals. At D+30, all signs of anxiety had disappeared. However, one-half of the rats still displayed bradypnea (DL rats, for low respiratory rate indicated by a lower RSA frequency), whereas those with higher respiratory rate (DH rats) had recovered. Acute blockade of the dorsomedial hypothalamus (DMH) or nucleus tractus solitarii (NTS) 5-HT3 receptors reversed bradypnea in all D rats at D+10 and in DL rats at D+30. Respiratory rate was also recorded in conscious animals implanted with radiotelemetric ECG probes. DH rats recovered between D+10 and D+18, whereas DL rats remained bradypneic until D+30. In conclusion, social stress induces sustained chronic bradypnea mediated by DMH neurons and NTS 5-HT3 receptors. These changes are associated with an anxiety-like state that persists until D+10, followed by recovery. However, bradypnea may persist in one-half of the population up until D+30, despite apparent recovery of the anxiety-like state.
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Affiliation(s)
- Charly Brouillard
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Institut National de la Santé et de la Recherche Médicale, UMR-S 975, Centre National de la Recherche Scientifique, UMR 7225, Faculté de Médecine University Pierre and Marie Curie, Site Pitié-Salpêtrière, Paris, France
- Sorbonne Universités, University Pierre and Marie Curie University Paris 06, Institut National de la Santé et de la Recherche Médicale, UMRS1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Pascal Carrive
- Blood Pressure, Brain and Behavior Laboratory, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Françoise Camus
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Institut National de la Santé et de la Recherche Médicale, UMR-S 975, Centre National de la Recherche Scientifique, UMR 7225, Faculté de Médecine University Pierre and Marie Curie, Site Pitié-Salpêtrière, Paris, France
| | - Jean-Jacques Bénoliel
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Institut National de la Santé et de la Recherche Médicale, UMR-S 975, Centre National de la Recherche Scientifique, UMR 7225, Faculté de Médecine University Pierre and Marie Curie, Site Pitié-Salpêtrière, Paris, France
| | - Thomas Similowski
- Sorbonne Universités, University Pierre and Marie Curie University Paris 06, Institut National de la Santé et de la Recherche Médicale, UMRS1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
- Assistance Publique-Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière, Charles Foix, Service de Pneumologie et Réanimation Médicale, Paris, France; and
| | - Caroline Sévoz-Couche
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Institut National de la Santé et de la Recherche Médicale, UMR-S 975, Centre National de la Recherche Scientifique, UMR 7225, Faculté de Médecine University Pierre and Marie Curie, Site Pitié-Salpêtrière, Paris, France
- Sorbonne Universités, University Pierre and Marie Curie University Paris 06, Institut National de la Santé et de la Recherche Médicale, UMRS1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
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Sévoz-Couche C, Brouillard C. Key role of 5-HT 3 receptors in the nucleus tractus solitarii in cardiovagal stress reactivity. Neurosci Biobehav Rev 2016; 74:423-432. [PMID: 27131969 DOI: 10.1016/j.neubiorev.2016.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 04/18/2016] [Accepted: 04/20/2016] [Indexed: 01/01/2023]
Abstract
Serotonin plays a modulatory role in central control of the autonomic nervous system (ANS). The nucleus tractus solitarii (NTS) in the medulla is an area of viscerosomatic integration innervated by both central and peripheral serotonergic fibers. Influences from different origins therefore trigger the release of serotonin into the NTS and exert multiple influences on the ANS. This major influence on the ANS is also mediated by activation of several receptors in the NTS. In particular, the NTS is the central zone with the highest density of serotonin3 (5-HT3) receptors. In this review, we present evidence that 5-HT3 receptors in the NTS play a key role in one of the crucial homeostatic responses to acute and chronic stress: inhibitory modulation of the parasympathetic component of the ANS. The possible functional interactions of 5-HT3 receptors with GABAA and NK1 receptors in the NTS are also discussed.
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Affiliation(s)
- Caroline Sévoz-Couche
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France.
| | - Charly Brouillard
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
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El Bitar N, Pollin B, Huang G, Mouraux A, Le Bars D. The rostral ventromedial medulla control of cutaneous vasomotion of paws and tail in the rat: implication for pain studies. J Neurophysiol 2015; 115:773-89. [PMID: 26581872 DOI: 10.1152/jn.00695.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/13/2015] [Indexed: 11/22/2022] Open
Abstract
Thermal neutrality in rodents is achieved by large cyclic variations of the sympathetic drive of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Given the pivotal functional role of rostral ventromedial medulla (RVM) in nociception and rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, we aimed at circumscribing the brainstem regions that are the source of premotor afferents to sympathetic preganglionic neurons that control the vasomotor tone of the tail and hind paws. A thermometric infrared camera recorded indirectly the vasomotor tone of the tail and hind paws. During the control period, the rat was maintained in vasoconstriction by preserving a stable, homogeneous, and constant surrounding temperature, slightly below the core temperature. The functional blockade of the RVM/rMR by the GABAA receptor agonist muscimol (0.5 nmol, 50 nl) elicited an extensive increase of the temperature of the paws and tail, associated with a slight decrease of blood pressure and heart rate. Both the increased heat loss through vasodilatation and the decrease heart-induced heat production elicited a remarkable reduction of the central temperature. The effective zones were circumscribed to the parts of the RVM/rMR facing the facial nucleus. They match very exactly the brain regions often described as specifically devoted to the control of nociception. Our data support and urge on the highest cautiousness regarding the interpretation of results aimed at studying the effects of any pharmacological manipulations of RVM/rMR with the usual tests of pain.
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Affiliation(s)
- Nabil El Bitar
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
| | - Bernard Pollin
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
| | - Gan Huang
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - André Mouraux
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Daniel Le Bars
- Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and
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Kabelik D, Alix VC, Singh LJ, Johnson AL, Choudhury SC, Elbaum CC, Scott MR. Neural activity in catecholaminergic populations following sexual and aggressive interactions in the brown anole, Anolis sagrei. Brain Res 2014; 1553:41-58. [PMID: 24472578 DOI: 10.1016/j.brainres.2014.01.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 01/16/2014] [Indexed: 01/01/2023]
Abstract
Social behaviors in vertebrates are modulated by catecholamine (CA; dopamine, norepinephrine, epinephrine) release within the social behavior neural network. Few studies have examined activity across CA populations in relation to social behaviors. The involvement of CAs in social behavior regulation is especially underexplored in reptiles, relative to other amniotes. In this study, we mapped CA populations throughout the brain (excluding retina and olfactory bulb) of the male brown anole lizard, Anolis sagrei, via immunofluorescent visualization of the rate-limiting enzyme for CA synthesis, tyrosine hydroxylase (TH). Colocalization of TH with the immediate early gene product Fos, an indirect marker of neural activity, also enabled us to relate activity in TH-immunoreactive (TH-ir) neurons to appetitive and consummatory sexual and aggressive behaviors. We detected most major TH-ir cell populations that are present in other amniotes (within the hypothalamus, midbrain, and hindbrain), although the A15 population was entirely absent. We also detected a few novel or rare cell clusters within the amygdala, medial septum, and inferior raphe. Many CA populations, especially dopaminergic groups, showed increased TH-Fos colocalization in association with appetitive and consummatory sexual behavior expression, while a small number of regions showed increased colocalization in relation to solely consummatory aggression (biting of an opponent). In conclusion, we here map CA populations throughout the brown anole brain and demonstrate evidence for catecholaminergic involvement in appetitive and consummatory sexual behaviors and consummatory aggressive behaviors in this species.
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Affiliation(s)
- David Kabelik
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA.
| | - Veronica C Alix
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
| | - Leah J Singh
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
| | - Alyssa L Johnson
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
| | - Shelley C Choudhury
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
| | - Caroline C Elbaum
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
| | - Madeline R Scott
- Department of Biology, Rhodes College, 2000 N Parkway, Memphis, TN 38112, USA
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Noxious stimulation excites serotonergic neurons: a comparison between the lateral paragigantocellular reticular and the raphe magnus nuclei. Pain 2012; 154:647-659. [PMID: 23142143 DOI: 10.1016/j.pain.2012.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 08/28/2012] [Accepted: 09/21/2012] [Indexed: 11/22/2022]
Abstract
The present study was designed to record electrophysiological responses to graded noxious thermal stimuli of serotonergic and nonserotonergic neurons in the lateral paragigantocellular reticular (LPGi) and the raphe magnus (RMg) nuclei in rats. All of the neurons recorded were juxtacellularly filled with neurobiotin and identified with double immunofluorescent labeling for both neurobiotin and serotonin. Under halothane anesthesia (0.75%), noxious thermal stimuli ⩾48°C activated almost all (88%) of the serotonergic neurons located within the LPGi (n=16). The increase in firing was clear (3.4±0.3spike/s: mean of responses above the population median) and sustained during the whole application of strong thermal noxious stimuli, with a high mean threshold (48.3±0.3°C) and large receptive fields. Recording of serotonergic neurons in the RMg (n=21) demonstrated that the proportion of strongly activated (>2spike/s) neurons (19% vs 59% for the LPGi) as well as the magnitude of the activation (2.1±0.4spike/s: mean of responses above the population median) to thermal noxious stimuli were significantly lower than in the LPGi (P<.05). Within the boundaries of both the LPGi and the RMg (B3 group), nonserotonergic neurons were also predominantly excited (75%) by noxious stimuli, and the resulting activation (7.9±1.2spike/s) was even greater than that of serotonergic neurons. Thermal noxious stimuli-induced activation of LPGi serotonergic cells probably plays a key role in serotonin-mediated modulations of cardiac baroreflex and transmission of nociceptive messages occurring under such intense noxious conditions.
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Takenaka R, Ohi Y, Haji A. Distinct modulatory effects of 5-HT on excitatory synaptic transmissions in the nucleus tractus solitarius of the rat. Eur J Pharmacol 2011; 671:45-52. [DOI: 10.1016/j.ejphar.2011.09.164] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 08/17/2011] [Accepted: 09/15/2011] [Indexed: 01/19/2023]
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Spirovski D, Li Q, Pilowsky PM. Brainstem galanin-synthesizing neurons are differentially activated by chemoreceptor stimuli and represent a subpopulation of respiratory neurons. J Comp Neurol 2011; 520:154-73. [DOI: 10.1002/cne.22723] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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11
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Netzer F, Bernard JF, Verberne AJM, Hamon M, Camus F, Benoliel JJ, Sévoz-Couche C. Brain circuits mediating baroreflex bradycardia inhibition in rats: an anatomical and functional link between the cuneiform nucleus and the periaqueductal grey. J Physiol 2011; 589:2079-91. [PMID: 21486808 DOI: 10.1113/jphysiol.2010.203737] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Defence responses triggered experimentally in rats by stimulation of the dorsomedial nucleus of the hypothalamus (DMH) and the dorsolateral periaqueductal grey matter (PAG) inhibit the cardiac baroreflex response (i.e. bradycardia). It has also been proposed that the midbrain cuneiform nucleus (CnF) is involved in active responses. Our aim was to identify the neurocircuitry involved in defence-induced baroreflex inhibition, with a particular focus on the link between DMH, CnF and dorsolateral PAG. Microinjection of the anterograde tracer Phaseolus vulgaris leucoaggutinin into the CnF revealed a dense projection to the dorsolateral PAG. Moreover, activation of neurons in the CnF induced increased expression of Fos protein in the dorsolateral PAG. Inhibition of neurons of the CnF or dorsolateral PAG prevented the inhibition of baroreflex bradycardia induced by DMH or CnF stimulation, respectively. These results provide a detailed description of the brain circuitry underlying acute baroreflex modulation by neurons of the DMH. Our data have shown for the first time that the CnF plays a key role in defence reaction-associated cardiovascular changes; its stimulation, from the DMH, activates the dorsolateral PAG, which, in turn, inhibits baroreflex bradycardia.
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Affiliation(s)
- Florence Netzer
- UPMC/INSERM, UMR-S 975 and CNRS UMR 7225, Faculté de médecine UPMC, Site Pitie-Salpêtrière, Paris F-75013, France
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12
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Fournet V, Jany M, Fabre V, Chali F, Orsal D, Schweitzer A, Andrieux A, Messanvi F, Giros B, Hamon M, Lanfumey L, Deloulme JC, Martres MP. The deletion of the microtubule-associated STOP protein affects the serotonergic mouse brain network. J Neurochem 2010; 115:1579-94. [PMID: 20969568 DOI: 10.1111/j.1471-4159.2010.07064.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The deletion of microtubule-associated protein stable tubule only polypeptide (STOP) leads to neuroanatomical, biochemical and severe behavioral alterations in mice, partly alleviated by antipsychotics. Therefore, STOP knockout (KO) mice have been proposed as a model of some schizophrenia-like symptoms. Preliminary data showed decreased brain serotonin (5-HT) tissue levels in STOP KO mice. As literature data demonstrate various interactions between microtubule-associated proteins and 5-HT, we characterized some features of the serotonergic neurotransmission in STOP KO mice. In the brainstem, mutant mice displayed higher tissue 5-HT levels and in vivo synthesis rate, together with marked increases in 5-HT transporter densities and 5-HT1A autoreceptor levels and electrophysiological sensitivity, without modification of the serotonergic soma number. Conversely, in projection areas, STOP KO mice exhibited lower 5-HT levels and in vivo synthesis rate, associated with severe decreases in 5-HT transporter densities, possibly related to reduced serotonergic terminals. Mutant mice also displayed a deficit of adult hippocampal neurogenesis, probably related to both STOP deletion and 5-HT depletion. Finally, STOP KO mice exhibited a reduced anxiety- and, probably, an increased helpness-status, that could be because of the strong imbalance of the serotonin neurotransmission between somas and terminals. Altogether, these data suggested that STOP deletion elicited peculiar 5-HT disconnectivity.
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Affiliation(s)
- Vincent Fournet
- INSERM UMRS 952, CNRS UMR 7224, Université Pierre et Marie Curie, Paris, France
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Inhibition of cardiac baroreflex by noxious thermal stimuli: A key role for lateral paragigantocellular serotonergic cells. Pain 2009; 146:315-324. [DOI: 10.1016/j.pain.2009.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 08/21/2009] [Accepted: 09/17/2009] [Indexed: 11/23/2022]
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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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Netzer F, Mandjee N, Verberne AJ, Bernard JF, Hamon M, Laguzzi R, Sévoz-Couche C. Inhibition of the bradycardic component of the von Bezold-Jarisch reflex and carotid chemoreceptor reflex by periaqueductal gray stimulation: involvement of medullary receptors. Eur J Neurosci 2009; 29:2017-28. [DOI: 10.1111/j.1460-9568.2009.06758.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Central 5-HT receptors in cardiovascular control during stress. Neurosci Biobehav Rev 2008; 33:95-106. [PMID: 18573276 DOI: 10.1016/j.neubiorev.2008.05.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 05/03/2008] [Accepted: 05/28/2008] [Indexed: 11/22/2022]
Abstract
Our aim is to consolidate recent data on relationship between central serotonergic neurotransmission and stress-elicited cardiovascular changes. Activation of central of 5-HT1A receptors attenuates tachycardic and pressor changes elicited by a wide range of stressors (airjet, restraint, open field, fear conditioning, social defeat), supporting the previous view of these receptors as "sympathoinhibitory". Their likely location is the medullary raphe. It is still unknown whether 5-TH1A receptors are sympathoinhibitory in physiological condition, as 5-HT1A antagonists do not affect basal or stress-altered cardiovascular parameters. In contrast to the established view that central 5-HT2A receptors are "sympathoexcitatory", experiments with new selective antagonists indicate that these receptors do not mediate stress-induced pressor and tachycardic responses, and are not involved in cardiovascular control at rest. The exception is control of cutaneous vascular bed, both at rest and during stress, likely at the spinal level. 5-HT3 receptors located in the nucleus tractus silitarius (NTS) contribute to stress-induced suppression of the baroreflex. 5-HT3 receptors located in sympathetic ganglia possibly contribute to the development of sustained hypertension in chronically stressed rats.
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