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Furdui A, da Silveira Scarpellini C, Montandon G. Anatomical distribution of µ-opioid receptors, neurokinin-1 receptors, and vesicular glutamate transporter 2 in the mouse brainstem respiratory network. J Neurophysiol 2024; 132:108-129. [PMID: 38748514 DOI: 10.1152/jn.00478.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 05/08/2024] [Accepted: 05/12/2024] [Indexed: 07/03/2024] Open
Abstract
µ-Opioid receptors (MORs) are responsible for mediating both the analgesic and respiratory effects of opioid drugs. By binding to MORs in brainstem regions involved in controlling breathing, opioids produce respiratory depressive effects characterized by slow and shallow breathing, with potential cardiorespiratory arrest and death during overdose. To better understand the mechanisms underlying opioid-induced respiratory depression, thorough knowledge of the regions and cellular subpopulations that may be vulnerable to modulation by opioid drugs is needed. Using in situ hybridization, we determined the distribution and coexpression of Oprm1 (gene encoding MORs) mRNA with glutamatergic (Vglut2) and neurokinin-1 receptor (Tacr1) mRNA in medullary and pontine regions involved in breathing control and modulation. We found that >50% of cells expressed Oprm1 mRNA in the preBötzinger complex (preBötC), nucleus tractus solitarius (NTS), nucleus ambiguus (NA), postinspiratory complex (PiCo), locus coeruleus (LC), Kölliker-Fuse nucleus (KF), and the lateral and medial parabrachial nuclei (LBPN and MPBN, respectively). Among Tacr1 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, Bötzinger complex (BötC), PiCo, LC, raphe magnus nucleus, KF, LPBN, and MPBN, whereas among Vglut2 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, BötC, PiCo, LC, KF, LPBN, and MPBN. Taken together, our study provides a comprehensive map of the distribution and coexpression of Oprm1, Tacr1, and Vglut2 mRNA in brainstem regions that control and modulate breathing and identifies Tacr1 and Vglut2 mRNA-expressing cells as subpopulations with potential vulnerability to modulation by opioid drugs.NEW & NOTEWORTHY Opioid drugs can cause serious respiratory side-effects by binding to µ-opioid receptors (MORs) in brainstem regions that control breathing. To better understand the regions and their cellular subpopulations that may be vulnerable to modulation by opioids, we provide a comprehensive map of Oprm1 (gene encoding MORs) mRNA expression throughout brainstem regions that control and modulate breathing. Notably, we identify glutamatergic and neurokinin-1 receptor-expressing cells as potentially vulnerable to modulation by opioid drugs and worthy of further investigation using targeted approaches.
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Affiliation(s)
- Andreea Furdui
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | | | - Gaspard Montandon
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Respirology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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2
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Andrzejewski K, Orłowska ME, Zaremba M, Joniec-Maciejak I, Kaczyńska K. Impact of Serotonergic 5HT 1A and 5HT 2A Receptor Activation on the Respiratory Response to Hypercapnia in a Rat Model of Parkinson's Disease. Int J Mol Sci 2024; 25:4403. [PMID: 38673988 PMCID: PMC11050428 DOI: 10.3390/ijms25084403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/09/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
In Parkinson's disease (PD), along with typical motor dysfunction, abnormal breathing is present; the cause of which is not well understood. The study aimed to analyze the effects of stimulation of the serotonergic system with 5-HT1A and 5-HT2A agonists in a model of PD induced by injection of 6-hydroxydopamine (6-OHDA). To model PD, bilateral injection of 6-OHDA into both striata was performed in male Wistar rats. Respiratory disturbances in response to 7% hypercapnia (CO2 in O2) in the plethysmographic chamber before and after stimulation of the serotonergic system and the incidence of apnea were studied in awake rats 5 weeks after 6-OHDA or vehicle injection. Administration of 6-OHDA reduced the concentration of serotonin (5-HT), dopamine (DA) and norepinephrine (NA) in the striatum and the level of 5-HT in the brainstem of treated rats, which have been associated with decreased basal ventilation, impaired respiratory response to 7% CO2 and increased incidence of apnea compared to Sham-operated rats. Intraperitoneal (i.p.) injection of the 5-HT1AR agonist 8-OH-DPAT and 5-HT2AR agonist NBOH-2C-CN increased breathing during normocapnia and hypercapnia in both groups of rats. However, it restored reactivity to hypercapnia in 6-OHDA group to the level present in Sham rats. Another 5-HT2AR agonist TCB-2 was only effective in increasing normocapnic ventilation in 6-OHDA rats. Both the serotonergic agonists 8-OH-DPAT and NBOH-2C-CN had stronger stimulatory effects on respiration in PD rats, compensating for deficits in basal ventilation and hypercapnic respiration. We conclude that serotonergic stimulation may have a positive effect on respiratory impairments that occur in PD.
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Affiliation(s)
- Kryspin Andrzejewski
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland; (K.A.); (M.E.O.)
| | - Magdalena E. Orłowska
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland; (K.A.); (M.E.O.)
| | - Małgorzata Zaremba
- Department of Experimental and Clinical Pharmacology, Centre for Preclinical Research (CePT), Medical University of Warsaw, 02-091 Warsaw, Poland; (M.Z.), (I.J.-M.)
| | - Ilona Joniec-Maciejak
- Department of Experimental and Clinical Pharmacology, Centre for Preclinical Research (CePT), Medical University of Warsaw, 02-091 Warsaw, Poland; (M.Z.), (I.J.-M.)
| | - Katarzyna Kaczyńska
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland; (K.A.); (M.E.O.)
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3
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Bernabe CS, Caliman IF, de Abreu ARR, Molosh AI, Truitt WA, Shekhar A, Johnson PL. Identification of a novel perifornical-hypothalamic-area-projecting serotonergic system that inhibits innate panic and conditioned fear responses. Transl Psychiatry 2024; 14:60. [PMID: 38272876 PMCID: PMC10811332 DOI: 10.1038/s41398-024-02769-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 01/06/2024] [Accepted: 01/10/2024] [Indexed: 01/27/2024] Open
Abstract
The serotonin (5-HT) system is heavily implicated in the regulation of anxiety and trauma-related disorders such as panic disorder and post-traumatic stress disorder, respectively. However, the neural mechanisms of how serotonergic neurotransmission regulates innate panic and fear brain networks are poorly understood. Our earlier studies have identified that orexin (OX)/glutamate neurons within the perifornical hypothalamic area (PFA) play a critical role in adaptive and pathological panic and fear. While site-specific and electrophysiological studies have shown that intracranial injection and bath application of 5-HT inhibits PFA neurons via 5-HT1a receptors, they largely ignore circuit-specific neurotransmission and its physiological properties that occur in vivo. Here, we investigate the role of raphe nuclei 5-HT inputs into the PFA in panic and fear behaviors. We initially confirmed that photostimulation of glutamatergic neurons in the PFA of rats produces robust cardioexcitation and flight/aversive behaviors resembling panic-like responses. Using the retrograde tracer cholera toxin B, we determined that the PFA receives discrete innervation of serotonergic neurons clustered in the lateral wings of the dorsal (lwDRN) and in the median (MRN) raphe nuclei. Selective lesions of these serotonergic projections with saporin toxin resulted in similar panic-like responses during the suffocation-related CO2 challenge and increased freezing to fear-conditioning paradigm. Conversely, selective stimulation of serotonergic fibers in the PFA attenuated both flight/escape behaviors and cardioexcitation responses elicited by the CO2 challenge and induced conditioned place preference. The data here support the hypothesis that PFA projecting 5-HT neurons in the lwDRN/MRN represents a panic/fear-off circuit and may also play a role in reward behavior.
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Affiliation(s)
- Cristian S Bernabe
- Department of Anatomy, Cellular Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Medicine, Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Izabela F Caliman
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Aline R R de Abreu
- Departamento de Alimentos, Escola de Nutrição da Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
| | - Andrei I Molosh
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - William A Truitt
- Department of Anatomy, Cellular Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Anantha Shekhar
- School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Philip L Johnson
- Department of Biology, University of South Dakota, Vermillion, SD, USA
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4
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Turk AZ, Millwater M, SheikhBahaei S. Whole-brain analysis of CO 2 chemosensitive regions and identification of the retrotrapezoid and medullary raphé nuclei in the common marmoset ( Callithrix jacchus). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.26.558361. [PMID: 37986845 PMCID: PMC10659419 DOI: 10.1101/2023.09.26.558361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Respiratory chemosensitivity is an important mechanism by which the brain senses changes in blood partial pressure of CO2 (PCO2). It is proposed that special neurons (and astrocytes) in various brainstem regions play key roles as CO2 central respiratory chemosensors in rodents. Although common marmosets (Callithrix jacchus), New-World non-human primates, show similar respiratory responses to elevated inspired CO2 as rodents, the chemosensitive regions in marmoset brain have not been defined yet. Here, we used c-fos immunostainings to identify brain-wide CO2-activated brain regions in common marmosets. In addition, we mapped the location of the retrotrapezoid nucleus (RTN) and raphé nuclei in the marmoset brainstem based on colocalization of CO2-induced c-fos immunoreactivity with Phox2b, and TPH immunostaining, respectively. Our data also indicated that, similar to rodents, marmoset RTN astrocytes express Phox2b and have complex processes that create a meshwork structure at the ventral surface of medulla. Our data highlight some cellular and structural regional similarities in brainstem of the common marmosets and rodents.
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Affiliation(s)
- Ariana Z. Turk
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
| | - Marissa Millwater
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
| | - Shahriar SheikhBahaei
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, 20892 MD, USA
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5
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Gonye EC, Bayliss DA. Criteria for central respiratory chemoreceptors: experimental evidence supporting current candidate cell groups. Front Physiol 2023; 14:1241662. [PMID: 37719465 PMCID: PMC10502317 DOI: 10.3389/fphys.2023.1241662] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/16/2023] [Indexed: 09/19/2023] Open
Abstract
An interoceptive homeostatic system monitors levels of CO2/H+ and provides a proportionate drive to respiratory control networks that adjust lung ventilation to maintain physiologically appropriate levels of CO2 and rapidly regulate tissue acid-base balance. It has long been suspected that the sensory cells responsible for the major CNS contribution to this so-called respiratory CO2/H+ chemoreception are located in the brainstem-but there is still substantial debate in the field as to which specific cells subserve the sensory function. Indeed, at the present time, several cell types have been championed as potential respiratory chemoreceptors, including neurons and astrocytes. In this review, we advance a set of criteria that are necessary and sufficient for definitive acceptance of any cell type as a respiratory chemoreceptor. We examine the extant evidence supporting consideration of the different putative chemoreceptor candidate cell types in the context of these criteria and also note for each where the criteria have not yet been fulfilled. By enumerating these specific criteria we hope to provide a useful heuristic that can be employed both to evaluate the various existing respiratory chemoreceptor candidates, and also to focus effort on specific experimental tests that can satisfy the remaining requirements for definitive acceptance.
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Affiliation(s)
- Elizabeth C. Gonye
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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6
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Yunoki T, Zang K, Hatano K, Matsuura R, Ohtsuka Y. Relationship between disturbances of CO 2 homeostasis and force output characteristics during isometric knee extension. Respir Physiol Neurobiol 2023; 315:104119. [PMID: 37468055 DOI: 10.1016/j.resp.2023.104119] [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: 04/16/2023] [Revised: 06/30/2023] [Accepted: 07/14/2023] [Indexed: 07/21/2023]
Abstract
To determine whether disturbances of CO2 homeostasis alter force output characteristics of lower limb muscles, participants performed four isometric knee extension trials (MVC30%, 10s each with 20-s rest intervals) in three CO2 conditions (normocapnia [NORM], hypercapnia [HYPER], and hypocapnia [HYPO]). Respiratory frequency and tidal volume were matched between CO2 conditions. In each MVC30%, the participants exerted a constant force (30% of maximum voluntary contraction [MVC]). The force coefficient of variation (Fcv) during each MVC30% and MVC before and after the four MVC30% trials were measured. For the means of the four trials, Fcv was significantly lower in HYPER than in HYPO. However, within HYPER, a significant positive correlation was found between the increase in end-tidal CO2 partial pressure and the increase in Fcv. MVCs in NORM and HYPO decreased significantly over the four trials, while no such reduction was observed in HYPER. These results suggest that perturbed CO2 homeostasis influences the force output characteristics independently of breathing pattern variables.
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Affiliation(s)
- Takahiro Yunoki
- Department of Health and Physical Education, Graduate School of Education, Hokkaido University, Sapporo, Japan.
| | - Kejun Zang
- Department of Health and Physical Education, Graduate School of Education, Hokkaido University, Sapporo, Japan
| | - Kei Hatano
- Japan Institute of Sports Sciences, Japan
| | - Ryouta Matsuura
- Graduate School of Education, Joetsu University of Education, Japan
| | - Yoshinori Ohtsuka
- Department of Sports and Human Studies, Sapporo International University, Japan
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7
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Jampolska M, Andrzejewski K, Boguszewski PM, Kaczyńska K. L-DOPA Improves Ventilation but Not the Ventilatory Response to Hypercapnia in a Reserpine Model of Parkinson's Disease. Brain Sci 2023; 13:brainsci13050775. [PMID: 37239247 DOI: 10.3390/brainsci13050775] [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: 04/04/2023] [Revised: 04/27/2023] [Accepted: 05/06/2023] [Indexed: 05/28/2023] Open
Abstract
Parkinson's disease (PD) is a neurological disorder characterized by progressive degeneration of the substantia nigra that affects mainly movement control. However, pathological changes associated with the development of PD may also alter respiration and can lead to chronic episodes of hypoxia and hypercapnia. The mechanism behind impaired ventilation in PD is unclear. Therefore, in this study, we explore the hypercapnic ventilatory response in a reproducible reserpine-induced (RES) model of PD and parkinsonism. We also investigated how dopamine supplementation with L-DOPA, a classic drug used to treat PD, would affect the breathing and respiratory response to hypercapnia. Reserpine treatment resulted in decreased normocapnic ventilation and behavioral changes manifested as low physical activity and exploratory behavior. The respiratory rate and the minute ventilation response to hypercapnia were significantly higher in sham rats compared to the RES group, while the tidal volume response was lower. All of this appears to be due to reduced baseline ventilation values produced by reserpine. L-DOPA reversed reduced ventilation, indicating a stimulatory effect of DA on breathing, and showed the potency of DA supplementation in restoring normal respiratory activity.
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Affiliation(s)
- Monika Jampolska
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland
| | - Kryspin Andrzejewski
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland
| | - Paweł M Boguszewski
- Laboratory of Animal Models, Neurobiology Centre, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Ludwika Pasteura 3 St., 02-093 Warsaw, Poland
| | - Katarzyna Kaczyńska
- Department of Respiration Physiology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5 St., 02-106 Warsaw, Poland
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8
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Biancardi V, Patrone LGA, Vicente MC, Marques DA, Bicego KC, Funk GD, Gargaglioni LH. Prenatal fluoxetine has long lasting, differential effects on respiratory control in male and female rats. J Appl Physiol (1985) 2022; 133:371-389. [PMID: 35708704 DOI: 10.1152/japplphysiol.00020.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT) is an important modulator of brain networks that control breathing. The selective serotonin reuptake inhibitor fluoxetine (FLX) is the first-line antidepressant drug prescribed during pregnancy. We investigated the effects of prenatal FLX on baseline breathing, ventilatory and metabolic responses to hypercapnia and hypoxia as well as number of brainstem 5-HT and tyrosine hydroxylase (TH) neurons of rats during postnatal development (P0-82). Prenatal FLX exposure of males showed a lower baseline that appeared in juveniles and remained in adulthood, with no sleep-wake state dependency. Prenatal FLX exposure of females did not affect baseline breathing. Juvenile male FLX rats showed increased CO2 and hypoxic ventilatory responses, normalizing by adulthood. Alterations in juvenile-FLX treated males were associated with greater number of 5-HT neurons in the ROB and RMAG. Adult FLX-exposed males showed greater number of 5-HT neurons in the RPA and TH neurons in the A5, while reduced number of TH neurons in A7. Prenatal FLX exposure of female rats was associated with greater hyperventilation induced by hypercapnia at P0-2 and juveniles whereas P12-14 and adult FLX (NREM sleep) rats showed an attenuation of the hypercapnic hyperventilation.FLX-exposed females had fewer 5-HT neurons in the RPA and reduced TH A6 density at P0-2; and greater number of TH neurons in the A7 at P12-14. These data indicate that prenatal FLX exposure affects the number of neurons of some monoaminergic regions in the brain and results in long lasting, sex specific changes in baseline breathing pattern and ventilatory responses to respiratory challenges.
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Affiliation(s)
- Vivian Biancardi
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil.,Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Luis Gustavo A Patrone
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil
| | - Mariane C Vicente
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil
| | - Danuzia A Marques
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil.,Department of Pediatrics, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, QC, Canada
| | - Kênia C Bicego
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil
| | - Gregory D Funk
- Department of Physiology, Faculty of Medicine and Dentistry, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University, Jaboticabal, Sao Paulo, Brazil
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9
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Jeton F, Perrin-Terrin AS, Yegen CH, Marchant D, Richalet JP, Pichon A, Boncoeur E, Bodineau L, Voituron N. In Transgenic Erythropoietin Deficient Mice, an Increase in Respiratory Response to Hypercapnia Parallels Abnormal Distribution of CO 2/H +-Activated Cells in the Medulla Oblongata. Front Physiol 2022; 13:850418. [PMID: 35514353 PMCID: PMC9061944 DOI: 10.3389/fphys.2022.850418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 03/21/2022] [Indexed: 12/03/2022] Open
Abstract
Erythropoietin (Epo) and its receptor are expressed in central respiratory areas. We hypothesized that chronic Epo deficiency alters functioning of central respiratory areas and thus the respiratory adaptation to hypercapnia. The hypercapnic ventilatory response (HcVR) was evaluated by whole body plethysmography in wild type (WT) and Epo deficient (Epo-TAgh) adult male mice under 4%CO2. Epo-TAgh mice showed a larger HcVR than WT mice because of an increase in both respiratory frequency and tidal volume, whereas WT mice only increased their tidal volume. A functional histological approach revealed changes in CO2/H+-activated cells between Epo-TAgh and WT mice. First, Epo-TAgh mice showed a smaller increase under hypercapnia in c-FOS-positive number of cells in the retrotrapezoid nucleus/parafacial respiratory group than WT, and this, independently of changes in the number of PHOX2B-expressing cells. Second, we did not observe in Epo-TAgh mice the hypercapnic increase in c-FOS-positive number of cells in the nucleus of the solitary tract present in WT mice. Finally, whereas hypercapnia did not induce an increase in the c-FOS-positive number of cells in medullary raphe nuclei in WT mice, chronic Epo deficiency leads to raphe pallidus and magnus nuclei activation by hyperacpnia, with a significant part of c-FOS positive cells displaying an immunoreactivity for serotonin in the raphe pallidus nucleus. All of these results suggest that chronic Epo-deficiency affects both the pattern of ventilatory response to hypercapnia and associated medullary respiratory network at adult stage with an increase in the sensitivity of 5-HT and non-5-HT neurons of the raphe medullary nuclei leading to stimulation of fR for moderate level of CO2.
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Affiliation(s)
- Florine Jeton
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Anne-Sophie Perrin-Terrin
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Celine-Hivda Yegen
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Dominique Marchant
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Jean-Paul Richalet
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Aurélien Pichon
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Emilie Boncoeur
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Laurence Bodineau
- Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Nicolas Voituron
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
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10
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Prowting J, Maresh S, Vaughan S, Kruppe E, Alsabri B, Badr MS, Sankari A. Mirtazapine reduces susceptibility to hypocapnic central sleep apnea in males with sleep-disordered breathing: a pilot study. J Appl Physiol (1985) 2021; 131:414-423. [PMID: 34080920 PMCID: PMC8325612 DOI: 10.1152/japplphysiol.00838.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 01/21/2023] Open
Abstract
Studies in humans and animal models with spinal cord injury (SCI) have demonstrated that medications targeting serotonin receptors may decrease the susceptibility to central sleep-disordered breathing (SDB). We hypothesized that mirtazapine would decrease the propensity to develop hypocapnic central sleep apnea (CSA) during sleep. We performed a single-blind pilot study on a total of 10 men with SDB (7 with chronic SCI and 3 noninjured) aged 52.0 ± 11.2 yr. Participants were randomly assigned to either mirtazapine (15 mg at bedtime) or a placebo for at least 1 wk, followed by a 7-day washout period before crossing over to the other intervention. Split-night studies included polysomnography and induction of hypocapnic CSA using a noninvasive ventilation (NIV) protocol. The primary outcome was CO2 reserve, defined as the difference between eupneic and end of NIV end-tidal CO2 ([Formula: see text]) preceding induced hypocapneic CSA. Secondary outcomes included controller gain (CG), other ventilatory parameters, and SDB severity. CG was defined as the ratio of change in minute ventilation (V̇e) between control and hypopnea to the change in CO2 during sleep. CO2 reserve was significantly widened on mirtazapine than placebo (-3.8 ± 1.2 vs. -2.0 ± 1.5 mmHg; P = 0.015). CG was significantly decreased on mirtazapine compared with placebo [2.2 ± 0.7 vs. 3.5 ± 1.9 L/(mmHg × min); P = 0.023]. There were no significant differences for other ventilatory parameters assessed or SDB severity between mirtazapine and placebo trials. These findings suggest that the administration of mirtazapine can decrease the susceptibility to central apnea by reducing chemosensitivity and increasing CO2 reserve; however, considering the lack of changes in apnea-hypopnea index (AHI), further research is required to understand the significance of this finding.NEW & NOTEWORTHY To our knowledge, this research study is novel as it is the first study in humans assessing the effect of mirtazapine on CO2 reserve and chemosensitivity in individuals with severe sleep-disordered breathing. This is also the first study to determine the potential therapeutic effects of mirtazapine on sleep parameters in individuals with a spinal cord injury.
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Affiliation(s)
- Joel Prowting
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - Scott Maresh
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - Sarah Vaughan
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - Elizabeth Kruppe
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - Bander Alsabri
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - M Safwan Badr
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
| | - Abdulghani Sankari
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Wayne State University School of Medicine, Detroit, Michigan
- Ascension Providence Hospital, Southfield, Michigan
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11
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5-HT neurons of the medullary raphe contribute to respiratory control in toads. Respir Physiol Neurobiol 2021; 293:103717. [PMID: 34119703 DOI: 10.1016/j.resp.2021.103717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 05/12/2021] [Accepted: 06/08/2021] [Indexed: 11/23/2022]
Abstract
Air-breathing vertebrates undergo respiratory adjustments when faced with disturbances in the gas composition of the environment. In mammals, the medullary raphe nuclei are involved in the neuronal pathway that mediates the ventilatory responses to hypoxia and hypercarbia. We investigate whether the serotoninergic neurons of the medullary raphe nuclei of toads (Rhinella diptycha) play a functional role in respiratory control during resting conditions (room air), hypercarbia (5% CO2), and hypoxia (5% O2). The raphe nuclei were located and identified based on the location of the serotoninergic neurons in the brainstem. We then lesioned the medullary raphe (raphe pallidus, obscurus and magnus) with anti-SERT-SAP and measured ventilation in both control and lesioned groups and we observed that serotonin (5-HT) specific chemical lesions of the medullary raphe caused reduced respiratory responses to both hypercarbia and hypoxia. In summary, we report that the serotoninergic neurons of the medullary raphe of the cururu toad Rhinella diptycha participate in the chemoreflex responses during hypercarbia and hypoxia, but not during resting conditions. This current evidence in anurans, together with the available data in mammals, brings insights to the evolution of brain sites, such as the medullary raphe, involved in the ventilatory chemoreflex in vertebrates.
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Leirão IP, Colombari DSA, da Silva GSF, Zoccal DB. Lesion of Serotonergic Afferents to the Retrotrapezoid Nucleus Impairs the Tachypneic Response to Hypercapnia in Unanesthetized Animals. Neuroscience 2020; 452:63-77. [PMID: 33212216 DOI: 10.1016/j.neuroscience.2020.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022]
Abstract
Hypercapnia promotes an increase in pulmonary ventilation due to the stimulation of brainstem chemosensory cells that are connected to the respiratory network. Among these cells are the raphe serotonergic neurons which widely send projections to distinct central respiratory compartments. Nevertheless, the physiological role of specific raphe serotonergic projections to other chemosensitive sites on the emergence of hypercapnia ventilatory response in vivo still remains to be elucidated. Here we investigated whether the ventilatory response to hypercapnia requires serotonergic inputs to the chemosensitive cells of the retrotrapezoid nucleus (RTN) in the ventrolateral medulla. To test this, pulmonary ventilation was evaluated under baseline conditions and during hypercapnia (7% CO2) in unanesthetized juvenile Holtzman rats (60-90 g) that received bilateral microinjections of either vehicle (control) or anti-SERT-SAP (0.1 mM, 10 pmol/100 nl) toxin in the RTN to retrogradely destroy serotonergic afferents to this region. Fifteen days after microinjections, baseline ventilation was not different between anti-SERT-SAP (n = 8) and control animals (n = 9). In contrast, the ablation of RTN-projecting serotonergic neurons markedly attenuated the hypercapnia-induced increase in respiratory frequency which was correlated with reduced numbers of serotonergic neurons in the raphe obscurus and magnus, but not in the raphe pallidus. The increase in tidal volume during hypercapnia was not significantly affected by anti-SERT-SAP microinjections in the RTN. Our data indicate that serotoninergic neurons that send projections to the RTN region are required for the processing of ventilatory reflex response during exposure to high CO2 in unanesthetized conditions.
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Affiliation(s)
- Isabela P Leirão
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics. Institute of Biological Sciences, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, MG, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, SP, Brazil.
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13
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Leirão IP, Zoccal DB, Gargaglioni LH, da Silva GSF. Differential modulation of active expiration during hypercapnia by the medullary raphe in unanesthetized rats. Pflugers Arch 2020; 472:1563-1576. [PMID: 32914212 DOI: 10.1007/s00424-020-02455-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/30/2020] [Accepted: 08/27/2020] [Indexed: 11/26/2022]
Abstract
Active expiration represents an important mechanism to improve ventilation in conditions of augmented ventilatory demand, such as hypercapnia. While a rostral ventromedullary region, the parafacial respiratory group (pFRG), has been identified as a conditional expiratory oscillator, little is known about how central chemosensitive sites contribute to modulate active expiration under hypercapnia. In this study, we investigated the influence of the medullary raphe in the emergence of phasic expiratory abdominal activity during hypercapnia in unanesthetized adult male rats, in a state-dependent manner. To do so, reverse microdialysis of muscimol (GABAA receptor agonist, 1 mM) or 8-OH-DPAT (5-HT1A agonist, 1 mM) was applied in the MR during sleep and wakefulness periods, both in normocapnic (room air) and hypercapnic conditions (7% CO2). Electromyography (EMG) of diaphragm and abdominal muscles was performed to measure inspiratory and expiratory motor outputs. We found that active expiration did not occur in room air exposure during wakefulness or sleep. However, hypercapnia did recruit active expiration, and differential effects were observed with the drug dialyses in the medullary raphe. Muscimol increased the diaphragm inspiratory motor output and also increased the amplitude and frequency of abdominal expiratory rhythmic activity during hypercapnia in wakefulness periods. On the other hand, the microdialysis of 8-OH-DPAT attenuated hypercapnia-induced active expiration in a state-dependent manner. Our data suggest that the medullary raphe can either inhibit or potentiate respiratory motor activity during hypercapnia, and the balance of these inhibitory or excitatory outputs may determine the expression of active expiration.
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Affiliation(s)
- Isabela P Leirão
- Department of Physiology and Pathology, School of Dentistry of Araraquara (FOAR), São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara (FOAR), São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University (FCAV-UNESP), Jaboticabal, SP, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics. Institute of Biological Sciences, Federal University of Minas Gerais (ICB/UFMG), Belo Horizonte, MG, Brazil.
- Departamento de Fisiologia e Biofísica, ICB/UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG, 31270-901, Brazil.
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14
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Maresh S, Prowting J, Vaughan S, Kruppe E, Alsabri B, Yarandi H, Badr MS, Sankari A. Buspirone decreases susceptibility to hypocapnic central sleep apnea in chronic SCI patients. J Appl Physiol (1985) 2020; 129:675-682. [PMID: 32816639 DOI: 10.1152/japplphysiol.00435.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spinal cord injury (SCI) is a risk factor for central sleep apnea (CSA). Previous studies in animal models with SCI have demonstrated a promising recovery in respiratory and phrenic nerve activity post-injury induced by the systemic and local administration of serotonin receptor agonists such as Buspirone and Trazodone. Human trials must be performed to determine whether individuals with SCI respond similarly. We hypothesized that Buspirone and Trazodone would decrease the propensity to hypocapnic CSA during sleep. We studied eight males with chronic SCI and sleep-disordered breathing (SDB) [age: 48.8 ± 14.2 yr; apnea-hypopnea index (AHI): 44.9 ± 23.1] in a single-blind crossover design. For 13 days, participants were randomly assigned either Buspirone (7.5-15 mg twice daily), Trazodone (100 mg), or a placebo followed by a 14-day washout period before crossing over to the other interventions. Study nights included polysomnography and induction of CSA using a noninvasive ventilation protocol. We assessed indexes of SDB, CO2 reserve, apneic threshold (AT), controller gain (CG), plant gain (PG), and ventilatory parameters. CO2 reserve was significantly widened on Buspirone (-3.6 ± 0.9 mmHg) compared with both Trazodone (-2.5 ± 1.0 mmHg, P = 0.009) and placebo (-1.8 ± 1.5 mmHg, P < 0.001) but not on Trazodone vs. placebo (P = 0.061). CG was significantly decreased on Buspirone compared with placebo (1.8 ± 0.4 vs. 4.0 ± 2.0 L/(mmHg·min), P = 0.025) but not on Trazodone compared with placebo (2.5 ± 1.1 vs. 4.0 ± 2.0 L/(mmHg·min); P = 0.065). There were no significant differences for PG, AT, or any SDB indexes (AHI, obstructive apnea index, central apnea index, oxygen desaturation index). The administration of Buspirone decreased the susceptibility to induced hypocapnic central apnea by reducing chemosensitivity and increasing CO2 reserve in chronic SCI patients.NEW & NOTEWORTHY This research study is novel as it is the first study in a humans that we are aware of that demonstrates the ability of Buspirone to increase CO2 reserve and hence decrease susceptibility to hypocapnic central apnea in patients with spinal cord injury.
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Affiliation(s)
- Scott Maresh
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | - Joel Prowting
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | - Sarah Vaughan
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | | | - Bander Alsabri
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | - Hossein Yarandi
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | - M Safwan Badr
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan
| | - Abdulghani Sankari
- Sleep Research Laboratory, John D. Dingell Veterans Affairs Medical Center, Wayne State University, Detroit, Michigan.,Ascension Providence Hospital, Southfield, Michigan
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15
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Avraam J, Wu Y, Richerson GB. Perinatal Nicotine Reduces Chemosensitivity of Medullary 5-HT Neurons after Maturation in Culture. Neuroscience 2020; 446:80-93. [PMID: 32818601 DOI: 10.1016/j.neuroscience.2020.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 08/07/2020] [Accepted: 08/10/2020] [Indexed: 01/19/2023]
Abstract
Perinatal exposure to nicotine produces ventilatory and chemoreflex deficits in neonatal mammals. Medullary 5-HT neurons are putative central chemoreceptors that innervate respiratory nuclei and promote ventilation, receive cholinergic input and express nicotinic acetylcholine receptors (nAChRs). Perforated patch clamp recordings were made from cultured 5-HT neurons dissociated from the medullary raphé of 0-3 day old mice expressing enhanced yellow fluorescent protein driven by the enhancer region for PET1 (ePet-EYFP). The effect of exposure to low (6 mg kg-1day-1) or high (60 mg kg-1day-1) doses of nicotine in utero (prenatal), in culture (postnatal), or both and the effect of acute nicotine exposure (10 μM), were examined on baseline firing rate (FR at 5% CO2, pH = 7.4) and the change in FR with acidosis (9% CO2, pH 7.2) in young (12-21 days in vitro, DIV) and older (≥22 DIV) acidosis stimulated 5-HT neurons. Nicotine exposed neurons exhibited ∼67% of the response to acidosis recorded in neurons given vehicle (p = 0.005), with older neurons exposed to high dose prenatal and postnatal nicotine, exhibiting only 28% of that recorded in the vehicle neurons (p < 0.01). In neurons exposed to low or high dose prenatal and postnatal nicotine, acute nicotine exposure led to a smaller increase in FR (∼+51% vs +168%, p = 0.026) and response to acidosis (+6% vs +67%, p = 0.014) compared to vehicle. These data show that exposure to nicotine during development reduces chemosensitivity of 5-HT neurons as they mature, an effect that may be related to the abnormal chemoreflexes reported in rodents exposed to nicotine in utero, and may cause a greater risk for sudden infant death syndrome (SIDS).
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Affiliation(s)
- Joanne Avraam
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Yuanming Wu
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - George Bradley Richerson
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Veteran's Affairs Medical Center, Iowa City, IA 52242, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA 52242, United States; Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, United States.
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16
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Szereda-Przestaszewska M, Kaczyńska K. Serotonin and substance P: Synergy or competition in the control of breathing. Auton Neurosci 2020; 225:102658. [PMID: 32145695 DOI: 10.1016/j.autneu.2020.102658] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 12/29/2022]
Abstract
Numerous neurotransmitters identified in the central nervous system play role in ventilatory control. This mini-review focuses on the respiratory effects of two neurotransmitters: serotonin (5-HT) and substance P (SP). We discuss their co-localization in medullary raphe nuclei, expression of proper receptors within the specific regions of respiratory related structures and contribution to respiratory rhythmogenesis.
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Affiliation(s)
- Małgorzata Szereda-Przestaszewska
- Department of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, A. Pawińskiego 5, 02-106 Warsaw, Poland
| | - Katarzyna Kaczyńska
- Department of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, A. Pawińskiego 5, 02-106 Warsaw, Poland.
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17
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Bernabe CS, Caliman IF, Truitt WA, Molosh AI, Lowry CA, Hay-Schmidt A, Shekhar A, Johnson PL. Using loss- and gain-of-function approaches to target amygdala-projecting serotonergic neurons in the dorsal raphe nucleus that enhance anxiety-related and conditioned fear behaviors. J Psychopharmacol 2020; 34:400-411. [PMID: 32153226 PMCID: PMC9678127 DOI: 10.1177/0269881119900981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The central serotonergic system originating from the dorsal raphe nucleus (DR) plays a critical role in anxiety and trauma-related disorders such as posttraumatic stress disorder. Although many studies have investigated the role of serotonin (5-HT) within pro-fear brain regions such as the amygdala, the majority of these studies have utilized non-selective pharmacological approaches or poorly understood lesioning techniques which limit their interpretation. AIM Here we investigated the role of amygdala-projecting 5-HT neurons in the DR in innate anxiety and conditioned fear behaviors. METHODS To achieve this goal, we utilized (1) selective lesion of 5-HT neurons projecting to the amygdala with saporin toxin conjugated to anti-serotonin transporter (SERT) injected into the amygdala, and (2) optogenetic excitation of amygdala-projecting DR cell bodies with a combination of a retrogradely transported canine adenovirus-expressing Cre-recombinase injected into the amygdala and a Cre-dependent-channelrhodopsin injected into the DR. RESULTS While saporin treatment lesioned both local amygdalar 5-HT fibers and neurons in the DR as well as reduced conditioned fear behavior, optical activation of amygdala-projecting DR neurons enhanced anxious behavior and conditioned fear response. CONCLUSION Collectively, these studies support the hypothesis that amygdala-projecting 5-HT neurons in the DR represent an anxiety and fear-on network.
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Affiliation(s)
- Cristian S. Bernabe
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Izabela F. Caliman
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - William A. Truitt
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrei I. Molosh
- Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Christopher A. Lowry
- Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | | | - Anantha Shekhar
- Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Philip L. Johnson
- Department of Anatomy & Cell Biology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Stark Neurosciences Research Institute, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
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18
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5-HT neurons and central CO2 chemoreception. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/b978-0-444-64125-0.00021-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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19
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Postnatal changes in O2 and CO2 sensitivity in rodents. Respir Physiol Neurobiol 2020; 272:103313. [DOI: 10.1016/j.resp.2019.103313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/31/2019] [Accepted: 10/02/2019] [Indexed: 02/06/2023]
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20
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Hulsey DR, Shedd CM, Sarker SF, Kilgard MP, Hays SA. Norepinephrine and serotonin are required for vagus nerve stimulation directed cortical plasticity. Exp Neurol 2019; 320:112975. [PMID: 31181199 DOI: 10.1016/j.expneurol.2019.112975] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/31/2019] [Accepted: 06/06/2019] [Indexed: 11/18/2022]
Abstract
Vagus nerve stimulation (VNS) paired with forelimb training drives robust, specific reorganization of movement representations in the motor cortex. This effect is hypothesized to be mediated by VNS-dependent engagement of neuromodulatory networks. VNS influences activity in the locus coeruleus (LC) and dorsal raphe nucleus (DRN), but the involvement of these neuromodulatory networks in VNS-directed plasticity is unknown. We tested the hypothesis that cortical norepinephrine and serotonin are required for VNS-dependent enhancement of motor cortex plasticity. Rats were trained on a lever pressing task emphasizing proximal forelimb use. Once proficient, all rats received a surgically implanted vagus nerve cuff and cortical injections of either immunotoxins to deplete serotonin or norepinephrine, or vehicle control. Following surgical recovery, rats received half second bursts of 0.8 mA or sham VNS after successful trials. After five days of pairing intracortical microstimulation (ICMS) was performed in the motor cortex contralateral to the trained limb. VNS paired with training more than doubled cortical representations of proximal forelimb movements. Depletion of either cortical norepinephrine or serotonin prevented this effect. The requirement of multiple neuromodulators is consistent with earlier studies showing that these neuromodulators regulate synaptic plasticity in a complimentary fashion.
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Affiliation(s)
- Daniel R Hulsey
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States of America.
| | - Christine M Shedd
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States of America
| | - Sadmaan F Sarker
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States of America
| | - Michael P Kilgard
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States of America; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States of America
| | - Seth A Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States of America; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States of America
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21
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Andrzejewski K, Budzińska K, Kaczyńska K. Effect of 6-OHDA on hypercapnic ventilatory response in the rat model of Parkinson's disease. Physiol Res 2019; 68:285-293. [PMID: 30628829 DOI: 10.33549/physiolres.933949] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Breathing impairments, such as an alteration in breathing pattern, dyspnoea, and sleep apnoea, are common health deficits recognised in Parkinson's disease (PD). The mechanism that underlies these disturbances, however, remains unclear. We investigated the effect of the unilateral damage to the rat nigrostriatal pathway on the central ventilatory response to hypercapnia, evoked by administering 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle (MFB). The respiratory experiments were carried out in conscious animals in the plethysmography chamber. The ventilatory parameters were studied in normocapnic and hyperoxic hypercapnia before and 14 days after the neurotoxin injection. Lesion with the 6-OHDA produced an increased tidal volume during normoxia. The magnified response of tidal volume and a decrease of breathing frequency to hypercapnia were observed in comparison to the pre-lesion and sham controls. Changes in both respiratory parameters resulted in an increase of minute ventilation of the response to CO(2) by 28% in comparison to the pre-lesion state at 60 s. Our results demonstrate that rats with implemented unilateral PD model presented an altered respiratory pattern most often during a ventilatory response to hypercapnia. Preserved noradrenaline and specific changes in dopamine and serotonin characteristic for this model could be responsible for the pattern of breathing observed during hypercapnia.
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Affiliation(s)
- K Andrzejewski
- Department of Respiration Physiology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
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22
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Bright FM, Vink R, Byard RW. The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS). Neuropeptides 2018; 70:1-8. [PMID: 29908886 DOI: 10.1016/j.npep.2018.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 02/25/2018] [Accepted: 02/25/2018] [Indexed: 12/30/2022]
Abstract
Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.
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Affiliation(s)
- Fiona M Bright
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia.
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Roger W Byard
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia
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23
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Holschbach MA, Vitale EM, Lonstein JS. Serotonin-specific lesions of the dorsal raphe disrupt maternal aggression and caregiving in postpartum rats. Behav Brain Res 2018; 348:53-64. [PMID: 29653128 DOI: 10.1016/j.bbr.2018.04.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/28/2018] [Accepted: 04/06/2018] [Indexed: 11/29/2022]
Abstract
The behavioral modifications associated with early motherhood, which include high aggression, caring for the young, and low anxiety, are all affected by acute pharmacological manipulation of serotonin signaling. However, the effects on all these behaviors of permanently disrupting serotonin signaling from one of its primary sources, the dorsal raphe nucleus (DR), have not been examined in detail. To address this, serotonin-specific lesions centered on the dorsomedial DR (DRdm; DR subregion strongly implicated in emotional behaviors) were induced at mid-pregnancy (day 15) or early postpartum (day 2) in rats using a saporin-conjugated neurotoxin targeting the serotonin transporter (Anti-SERT-SAP). Prepartum or postpartum Anti-SERT-SAP reduced DRdm serotonin immunoreactivity by ∼40-65%, and postpartum Anti-SERT-SAP also reduced it in the ventromedial and lateral wings of the DR, as well as in the median raphe. Serotonin-immunoreactive fibers were significantly reduced in the anterior hypothalamus, but not medial preoptic area, of lesioned dams. Pre- or postpartum lesions both greatly reduced maternal aggression, but while prepartum lesions did not affect later undisturbed maternal caregiving, the larger postpartum lesions prevented the postpartum decline in kyphotic nursing and reduced pup licking. Serotonin lesions did not affect pup retrieval, but the prepartum lesions temporarily increased maternal hovering over and licking the pups observed immediately after the disruptive retrieval tests. Dams' anxiety-like behaviors and litter weight gains were unaffected by the lesions. These findings suggest that DRdm serotonin projecting to the AH is particularly critical for maternal aggression, but that more widespread disruption of midbrain raphe serotonin is necessary to greatly impair maternal caregiving. Postpartum anxiety may rely more on other neurochemical systems or different midbrain serotonergic cell populations.
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Affiliation(s)
- M Allie Holschbach
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA
| | - Erika M Vitale
- Department of Psychology, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA
| | - Joseph S Lonstein
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA; Department of Psychology, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA.
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Bright FM, Byard RW, Vink R, Paterson DS. Normative distribution of substance P and its tachykinin neurokinin-1 receptor in the medullary serotonergic network of the human infant during postnatal development. Brain Res Bull 2018; 137:319-328. [PMID: 29331576 DOI: 10.1016/j.brainresbull.2018.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/09/2018] [Indexed: 10/18/2022]
Abstract
Substance P (SP) and its tachykinin NK1 receptor (NK1R) function within key medullary nuclei to regulate cardiorespiratory and autonomic control. We examined the normative distribution of SP and NK1R in the serotonergic (5-Hydroxytryptamine, [5-HT]) network of the human infant medulla during postnatal development, to provide a baseline to facilitate future analysis of the SP/NK1R system and its interaction with 5-HT within pediatric brainstem disorders in early life. [125I] labelled Bolton Hunter SP (BH-SP) tissue receptor autoradiography (n = 15), single label immunohistochemistry (IHC) and double label immunofluorescence (IF) (n = 10) were used to characterize the normative distribution profile of SP and NK1R in the 5-HT network of the human infant medulla during postnatal development. Tissue receptor autoradiography revealed extensive distribution of SP and NK1R in nuclei intimately related to cardiorespiratory function and autonomic control, with significant co-distribution and co-localization with 5-HT in the medullary network in the normal human infant during development. A trend for NK1R binding to decrease with age was observed with significantly higher binding in premature and male infants. We provide further evidence to suggest a significant role for SP/NK1R in the early postnatal period in the modulation of medullary cardiorespiratory and autonomic control in conjunction with medullary 5-HT mediated pathways and provide a baseline for future analysis of the potential consequences of abnormalities in these brainstem neurotransmitter networks during development.
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Affiliation(s)
- Fiona M Bright
- Harvard University Medical School, Boston, MA, USA; School of Medicine, University of Adelaide SA, Australia; Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Roger W Byard
- School of Medicine, University of Adelaide SA, Australia
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - David S Paterson
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
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Bright FM, Vink R, Byard RW, Duncan JR, Krous HF, Paterson DS. Abnormalities in substance P neurokinin-1 receptor binding in key brainstem nuclei in sudden infant death syndrome related to prematurity and sex. PLoS One 2017; 12:e0184958. [PMID: 28931039 PMCID: PMC5607183 DOI: 10.1371/journal.pone.0184958] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/05/2017] [Indexed: 12/15/2022] Open
Abstract
Sudden infant death syndrome (SIDS) involves failure of arousal to potentially life threatening events, including hypoxia, during sleep. While neuronal dysfunction and abnormalities in neurotransmitter systems within the medulla oblongata have been implicated, the specific pathways associated with autonomic and cardiorespiratory failure are unknown. The neuropeptide substance P (SP) and its tachykinin neurokinin-1 receptor (NK1R) have been shown to play an integral role in the modulation of homeostatic function in the medulla, including regulation of respiratory rhythm generation, integration of cardiovascular control, and modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may therefore result in autonomic dysfunction during sleep and contribute to SIDS deaths. [125I] Bolton Hunter SP autoradiography was used to map the distribution and density of the SP, NK1R to 13 specific nuclei intimately related to cardiorespiratory function and autonomic control in the human infant medulla of 55 SIDS and 21 control (non-SIDS) infants. Compared to controls, SIDS cases exhibited a differential, abnormal developmental profile of the SP/NK1R system in the medulla. Furthermore the study revealed significantly decreased NK1R binding within key medullary nuclei in SIDS cases, principally in the nucleus tractus solitarii (NTS) and all three subdivisions of the inferior portion of the olivo-cerebellar complex; the principal inferior olivary complex (PIO), medial accessory olive (MAO) and dorsal accessory olive (DAO). Altered NK1R binding was significantly influenced by prematurity and male sex, which may explain the increased risk of SIDS in premature and male infants. Abnormal NK1R binding in these medullary nuclei may contribute to the defective interaction of critical medullary mechanisms with cerebellar sites, resulting in an inability of a SIDS infant to illicit appropriate respiratory and motor responses to life threatening challenges during sleep. These observations support the concept that abnormalities in a multi-neurotransmitter network within key nuclei of the medullary homeostatic system may underlie the pathogenesis of a subset of SIDS cases.
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Affiliation(s)
- Fiona M. Bright
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
- Department of Pathology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, United States of America
- * E-mail:
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Roger W. Byard
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Jhodie R. Duncan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Henry F. Krous
- Department of Pathology, Children’s Hospital-San Diego, San Diego, CA, United States of America
| | - David S. Paterson
- Department of Pathology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, United States of America
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Oliveira LM, Tuppy M, Moreira TS, Takakura AC. Role of the locus coeruleus catecholaminergic neurons in the chemosensory control of breathing in a Parkinson's disease model. Exp Neurol 2017; 293:172-180. [DOI: 10.1016/j.expneurol.2017.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 04/11/2017] [Accepted: 04/14/2017] [Indexed: 01/05/2023]
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Beltrán-Castillo S, Morgado-Valle C, Eugenín J. The Onset of the Fetal Respiratory Rhythm: An Emergent Property Triggered by Chemosensory Drive? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:163-192. [PMID: 29080027 DOI: 10.1007/978-3-319-62817-2_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mechanisms responsible for the onset of respiratory activity during fetal life are unknown. The onset of respiratory rhythm may be a consequence of the genetic program of each of the constituents of the respiratory network, so they start to interact and generate respiratory cycles when reaching a certain degree of maturation. Alternatively, generation of cycles might require the contribution of recently formed sensory inputs that will trigger oscillatory activity in the nascent respiratory neural network. If this hypothesis is true, then sensory input to the respiratory generator must be already formed and become functional before the onset of fetal respiration. In this review, we evaluate the timing of the onset of the respiratory rhythm in comparison to the appearance of receptors, neurotransmitter machinery, and afferent projections provided by two central chemoreceptive nuclei, the raphe and locus coeruleus nuclei.
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Affiliation(s)
- Sebastián Beltrán-Castillo
- Laboratorio de Sistemas Neurales, Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, PO 9170022, Santiago, Chile
| | - Consuelo Morgado-Valle
- Centro de Investigaciones Cerebrales, Universidad Veracruzana, Campus Xalapa, Berlin 7, Fracc., Monte Magno Animas, C.P. 91190, Xalapa, Veracruz, Mexico.
| | - Jaime Eugenín
- Laboratorio de Sistemas Neurales, Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, PO 9170022, Santiago, Chile.
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Cerpa VJ, Wu Y, Bravo E, Teran FA, Flynn RS, Richerson GB. Medullary 5-HT neurons: Switch from tonic respiratory drive to chemoreception during postnatal development. Neuroscience 2016; 344:1-14. [PMID: 27619736 DOI: 10.1016/j.neuroscience.2016.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 01/27/2023]
Abstract
Serotonin (5-HT) neurons contribute to respiratory chemoreception in adult mice, but it is unclear whether they play a similar role in neonatal mice. We studied breathing during development in Lmx1bf/f/p mice, which lack 5-HT neurons. From postnatal days 1-7 (P1-P7), ventilation of Lmx1bf/f/p mice breathing room air was 50% of WT mice (p<0.001). By P12, baseline ventilation increased to a level equal to WT mice. In contrast, the hypercapnic ventilatory response (HCVR) of neonatal Lmx1bf/f/p and WT mice was equal to each other, but were both much less than adult WT mice. By P21 the HCVR of WT mice increased to near adult levels, but the HCVR of Lmx1bf/f/p mice had not changed, and was 42% less than WT mice. Primary cell cultures were prepared from the ventromedial medulla of neonatal mice, and patch-clamp recordings were made from neurons identified as serotonergic by expression of a reporter gene. In parallel with developmental changes of the HCVR in vivo, 5-HT neurons had little chemosensitivity to acidosis until 12days in vitro (DIV), after which their response increased to reach a plateau around 25 DIV. Neonatal Lmx1bf/f/p mice displayed high mortality and decreased growth rate, and this worsened in hypoxia. Mortality was decreased in hyperoxia. These results indicate that maturation of 5-HT neurons contributes to development of respiratory CO2/pH chemoreception during the first few weeks of life in mice in vivo. A defect in the 5-HT system in early postnatal life decreases survival due in part to hypoxia.
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Affiliation(s)
- Veronica J Cerpa
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Yuanming Wu
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States.
| | - Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA 52242, United States
| | - Rachel S Flynn
- Department of Neurology, Yale University, New Haven, CT 06510, United States
| | - George B Richerson
- Department of Neurology, Yale University, New Haven, CT 06510, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA 52242, United States; Veterans Affairs Medical Center, Iowa City, IA 52242, United States
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Granjeiro ÉM, da Silva GSF, Giusti H, Oliveira JA, Glass ML, Garcia-Cairasco N. Behavioral, Ventilatory and Thermoregulatory Responses to Hypercapnia and Hypoxia in the Wistar Audiogenic Rat (WAR) Strain. PLoS One 2016; 11:e0154141. [PMID: 27149672 PMCID: PMC4858153 DOI: 10.1371/journal.pone.0154141] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 04/08/2016] [Indexed: 01/20/2023] Open
Abstract
INTRODUCTION We investigated the behavioral, respiratory, and thermoregulatory responses elicited by acute exposure to both hypercapnic and hypoxic environments in Wistar audiogenic rats (WARs). The WAR strain represents a genetic animal model of epilepsy. METHODS Behavioral analyses were performed using neuroethological methods, and flowcharts were constructed to illustrate behavioral findings. The body plethysmography method was used to obtain pulmonary ventilation (VE) measurements, and body temperature (Tb) measurements were taken via temperature sensors implanted in the abdominal cavities of the animals. RESULTS No significant difference was observed between the WAR and Wistar control group with respect to the thermoregulatory response elicited by exposure to both acute hypercapnia and acute hypoxia (p>0.05). However, we found that the VE of WARs was attenuated relative to that of Wistar control animals during exposure to both hypercapnic (WAR: 133 ± 11% vs. Wistar: 243 ± 23%, p<0.01) and hypoxic conditions (WAR: 138 ± 8% vs. Wistar: 177 ± 8%; p<0.01). In addition, we noted that this ventilatory attenuation was followed by alterations in the behavioral responses of these animals. CONCLUSIONS Our results indicate that WARs, a genetic model of epilepsy, have important alterations in their ability to compensate for changes in levels of various arterial blood gasses. WARs present an attenuated ventilatory response to an increased PaCO2 or decreased PaO2, coupled to behavioral changes, which make them a suitable model to further study respiratory risks associated to epilepsy.
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Affiliation(s)
- Érica Maria Granjeiro
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
| | - Glauber S. F. da Silva
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
| | - Humberto Giusti
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
| | - José Antonio Oliveira
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
| | - Mogens Lesner Glass
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
| | - Norberto Garcia-Cairasco
- Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, 14049–900, Ribeirão Preto, SP, Brazil
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Role of Astrocytes in Central Respiratory Chemoreception. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:109-145. [PMID: 27714687 DOI: 10.1007/978-3-319-40764-7_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Astrocytes perform various homeostatic functions in the nervous system beyond that of a supportive or metabolic role for neurons. A growing body of evidence indicates that astrocytes are crucial for central respiratory chemoreception. This review presents a classical overview of respiratory central chemoreception and the new evidence for astrocytes as brainstem sensors in the respiratory response to hypercapnia. We review properties of astrocytes for chemosensory function and for modulation of the respiratory network. We propose that astrocytes not only mediate between CO2/H+ levels and motor responses, but they also allow for two emergent functions: (1) Amplifying the responses of intrinsic chemosensitive neurons through feedforward signaling via gliotransmitters and; (2) Recruiting non-intrinsically chemosensitive cells thanks to volume spreading of signals (calcium waves and gliotransmitters) to regions distant from the CO2/H+ sensitive domains. Thus, astrocytes may both increase the intensity of the neuron responses at the chemosensitive sites and recruit of a greater number of respiratory neurons to participate in the response to hypercapnia.
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Cerpa VJ, Aylwin MDLLO, Beltrán-Castillo S, Bravo EU, Llona IR, Richerson GB, Eugenín JL. The Alteration of Neonatal Raphe Neurons by Prenatal-Perinatal Nicotine. Meaning for Sudden Infant Death Syndrome. Am J Respir Cell Mol Biol 2015; 53:489-99. [PMID: 25695895 DOI: 10.1165/rcmb.2014-0329oc] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Nicotine may link maternal cigarette smoking with respiratory dysfunctions in sudden infant death syndrome (SIDS). Prenatal-perinatal nicotine exposure blunts ventilatory responses to hypercapnia and reduces central respiratory chemoreception in mouse neonates at Postnatal Days 0 (P0) to P3. This suggests that raphe neurons, which are altered in SIDS and contribute to central respiratory chemoreception, may be affected by nicotine. We therefore investigated whether prenatal-perinatal nicotine exposure affects the activity, electrical properties, and chemosensitivity of raphe obscurus (ROb) neurons in mouse neonates. Osmotic minipumps, implanted subcutaneously in 5- to 7-day-pregnant CF1 mice, delivered nicotine bitartrate (60 mg kg(-1) d(-1)) or saline (control) for up to 28 days. In neonates, ventilation was recorded by head-out plethysmography, c-Fos (neuronal activity marker), or serotonin autoreceptors (5HT1AR) were immunodetected using light microscopy, and patch-clamp recordings were made from raphe neurons in brainstem slices under normocarbia and hypercarbia. Prenatal-perinatal nicotine exposure decreased the hypercarbia-induced ventilatory responses at P1-P5, reduced both the number of c-Fos-positive ROb neurons during eucapnic normoxia at P1-P3 and their hypercapnia-induced recruitment at P3, increased 5HT1AR immunolabeling of ROb neurons at P3-P5, and reduced the spontaneous firing frequency of ROb neurons at P3 without affecting their CO2 sensitivity or their passive and active electrical properties. These findings reveal that prenatal-perinatal nicotine reduces the activity of neonatal ROb neurons, likely as a consequence of increased expression of 5HT1ARs. This hypoactivity may change the functional state of the respiratory neural network leading to breathing vulnerability and chemosensory failure as seen in SIDS.
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Affiliation(s)
- Verónica J Cerpa
- 1 Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,2 Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Chile.,Departments of 3 Neurology and.,4 Facultad de Medicina, Universidad del Desarrollo, Santiago, Chile
| | | | - Sebastián Beltrán-Castillo
- 2 Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Chile
| | - Eduardo U Bravo
- 2 Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Chile
| | - Isabel R Llona
- 2 Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Chile
| | - George B Richerson
- Departments of 3 Neurology and.,6 Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa.,7 Veteran's Affairs Medical Center, Iowa City, Iowa; and
| | - Jaime L Eugenín
- 2 Facultad de Química y Biología, Departamento de Biología, Universidad de Santiago de Chile, USACH, Chile
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The brain acid–base homeostasis and serotonin: A perspective on the use of carbon dioxide as human and rodent experimental model of panic. Prog Neurobiol 2015; 129:58-78. [DOI: 10.1016/j.pneurobio.2015.04.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 04/16/2015] [Accepted: 04/20/2015] [Indexed: 12/14/2022]
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Cerpa V, Gonzalez A, Richerson GB. Diphtheria toxin treatment of Pet-1-Cre floxed diphtheria toxin receptor mice disrupts thermoregulation without affecting respiratory chemoreception. Neuroscience 2014; 279:65-76. [PMID: 25171790 DOI: 10.1016/j.neuroscience.2014.08.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 08/11/2014] [Accepted: 08/11/2014] [Indexed: 11/17/2022]
Abstract
In genetically-modified Lmx1b(f/f/p) mice, selective deletion of LMX1B in Pet-1 expressing cells leads to failure of embryonic development of serotonin (5-HT) neurons. As adults, these mice have a decreased hypercapnic ventilatory response and abnormal thermoregulation. This mouse model has been valuable in defining the normal role of 5-HT neurons, but it is possible that developmental compensation reduces the severity of observed deficits. Here we studied mice genetically modified to express diphtheria toxin receptors (DTR) on Pet-1 expressing neurons (Pet-1-Cre/floxed DTR or Pet1/DTR mice). These mice developed with a normal complement of 5-HT neurons. As adults, systemic treatment with 2-35μg of diphtheria toxin (DT) reduced the number of tryptophan hydroxylase-immunoreactive (TpOH-ir) neurons in the raphe nuclei and ventrolateral medulla by 80%. There were no effects of DT on minute ventilation (VE) or the ventilatory response to hypercapnia or hypoxia. At an ambient temperature (TA) of 24°C, all Pet1/DTR mice dropped their body temperature (TB) below 35°C after DT treatment, but the latency was shorter in males than females (3.0±0.37 vs. 4.57±0.29days, respectively; p<0.001). One week after DT treatment, mice were challenged by dropping TA from 37°C to 24°C, which caused TB to decrease more in males than in females (29.7±0.31°C vs. 33.0±1.3°C, p<0.01). We conclude that the 20% of 5-HT neurons that remain after DT treatment in Pet1/DTR mice are sufficient to maintain normal baseline breathing and a normal response to CO2, while those affected include some essential for thermoregulation, in males more than females. In comparison to models with deficient embryonic development of 5-HT neurons, acute deletion of 5-HT neurons in adults leads to a greater defect in thermoregulation, suggesting that significant developmental compensation can occur.
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Affiliation(s)
- V Cerpa
- Department of Neurology, Yale University, New Haven, CT 06520, United States; Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA 52242, United States; Departamento de Fisiología, Facultad de Medicina, Universidad del Desarrollo, Santiago 8320000, Chile
| | - A Gonzalez
- Department of Neurology, Yale University, New Haven, CT 06520, United States; Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, United States
| | - G B Richerson
- Department of Neurology, Yale University, New Haven, CT 06520, United States; Department of Cellular & Molecular Physiology, Yale University, New Haven, CT 06520, United States; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA 52242, United States; Veterans Affairs Medical Center, Iowa City, IA 52242, United States.
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Iceman KE, Corcoran AE, Taylor BE, Harris MB. CO2-inhibited neurons in the medullary raphé are GABAergic. Respir Physiol Neurobiol 2014; 203:28-34. [PMID: 25087734 DOI: 10.1016/j.resp.2014.07.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 07/24/2014] [Accepted: 07/24/2014] [Indexed: 11/28/2022]
Abstract
Previous studies have reported subsets of medullary raphé neurons that are either stimulated or inhibited by CO2/pH in vitro, in situ, and in vivo. We tested the hypothesis that medullary raphé CO2-inhibited neurons are GABAergic. Extracellular recordings in unanesthetized juvenile in situ rat preparations showed reversible hypercapnia-induced suppression of 19% (63/323) of medullary raphé neurons, and this suppression persisted after antagonism of NMDA, AMPA/kainate, and GABAA receptors. We stained a subset of CO2-inhibited cells and found that most (11/12) had glutamic acid decarboxylase 67 immunoreactivity (GAD67-ir). These data indicate that the majority of acidosis-inhibited medullary raphé neurons are GABAergic, and that their chemosensitivity is independent of major fast synaptic inputs. Thus, CO2-sensitive GABAergic neurons may play a role in central CO2/pH chemoreception.
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Affiliation(s)
- Kimberly E Iceman
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Andrea E Corcoran
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Barbara E Taylor
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Michael B Harris
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
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Raphe serotonergic neurons modulate genioglossus corticomotor activity in intermittent hypoxic rats. Respir Res 2014; 15:76. [PMID: 25001907 PMCID: PMC4100526 DOI: 10.1186/1465-9921-15-76] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 07/01/2014] [Indexed: 11/26/2022] Open
Abstract
Background Genioglossus activity is greater during wakefulness but decreases to a weaker state during sleep in obstructive sleep apnea syndrome (OSAS) patients, compared to healthy subjects. Previous studies suggested that the corticomotor control of the genioglossus was modified in OSAS patients. Intermittent hypoxia (IH), the typical pathophysiological change in OSAS, can induce genioglossus facilitation. The serotonergic neurons of the raphe dorsal (DRN) and magnus nuclei (RMg) are responsive to hypoxia and play important roles in the control of the genioglossus. However, it remains unknown whether DRN and RMg serotonergic neurons are responsible for the facilitated corticomotor activity of the genioglossus during IH. This study explored the influence of IH on the corticomotor activity of the genioglossus by transcranial magnetic stimulation (TMS), and the role of DRN and RMg serotonergic neurons in this effect. Methods Rats were exposed to IH and divided into two groups. In one group, anti-SERT-SAP was microinjected into the DRN and RMg respectively to kill serotonergic neurons. In the other group, artificial cerebrospinal fluid (ACSF) was injected. Comparisons were conducted between the two groups during four weeks of IH and four weeks after IH. Results Compared to the corresponding ACSF-injected group, the DRN lesion group and RMg lesion group showed longer TMS latencies and lower amplitudes during IH from the 1st to the 28th day. After 28 days of IH, longer latencies and lower amplitudes were seen only in the DRN lesion group. Conclusion These results indicate that DRN and RMg serotonergic neurons play different roles in the facilitation of genioglossus corticomotor activity induced by IH.
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Substance P differentially modulates firing rate of solitary complex (SC) neurons from control and chronic hypoxia-adapted adult rats. PLoS One 2014; 9:e88161. [PMID: 24516602 PMCID: PMC3917864 DOI: 10.1371/journal.pone.0088161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 01/03/2014] [Indexed: 11/19/2022] Open
Abstract
NK1 receptors, which bind substance P, are present in the majority of brainstem regions that contain CO2/H(+)-sensitive neurons that play a role in central chemosensitivity. However, the effect of substance P on the chemosensitive response of neurons from these regions has not been studied. Hypoxia increases substance P release from peripheral afferents that terminate in the caudal nucleus tractus solitarius (NTS). Here we studied the effect of substance P on the chemosensitive responses of solitary complex (SC: NTS and dorsal motor nucleus) neurons from control and chronic hypoxia-adapted (CHx) adult rats. We simultaneously measured intracellular pH and electrical responses to hypercapnic acidosis in SC neurons from control and CHx adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. Substance P significantly increased the basal firing rate in SC neurons from control and CHx rats, although the increase was smaller in CHx rats. However, substance P did not affect the chemosensitive response of SC neurons from either group of rats. In conclusion, we found that substance P plays a role in modulating the basal firing rate of SC neurons but the magnitude of the effect is smaller for SC neurons from CHx adult rats, implying that NK1 receptors may be down regulated in CHx adult rats. Substance P does not appear to play a role in modulating the firing rate response to hypercapnic acidosis of SC neurons from either control or CHx adult rats.
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Astrocytes in the rat nucleus tractus solitarii are critical for cardiovascular reflex control. J Neurosci 2014; 33:18608-17. [PMID: 24259582 DOI: 10.1523/jneurosci.3257-13.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have shown that an antibody to dopamine-β-hydroxylase conjugated with saporin (anti-DBH-SAP) damages catecholamine neurons in the nucleus tractus solitarii (NTS) of rat, attenuates arterial baroreflexes, and leads to lability of arterial blood pressure, damage to cardiac myocytes, and, in some animals, sudden death. However, others have shown that injection of 6-hydroxydopamine (6-OHDA), a toxin devoid of saporin, also damaged NTS catecholamine neurons but did not lead to these cardiovascular changes. We found similar cardiovascular changes after injecting a different SAP conjugate to target NTS neurons with neurokinin (NK1) receptors. Because ribosome-inactivating proteins may be toxic to glia, we hypothesized that SAP, a ribosome-inactivating protein, might target glia whose loss could account for physiological changes. We tested this hypothesis by assessing effects on select neurons and on glia in the NTS after exposure to SAP, targeted SAP conjugates, or 6-OHDA. SAP and all SAP conjugates led to loss of immunoreactivity for glial fibrillary acidic protein, a marker for astrocytes, in the NTS while 6-OHDA did not. As reported previously, anti-DBH-SAP selectively killed noradrenergic neurons in the NTS while SAP conjugated to stabilized substance P (SSP-SAP) selectively killed neurons with NK1 receptors. In contrast, SAP produced no demonstrable neuronal damage. All injections led to activation of microglia in the NTS; however, only SAP and its conjugates attenuated cardiovascular reflexes while also producing lability of arterial pressure, damage to cardiac myocytes, and in some animals, sudden death. Thus, NTS astrocytes may play a role in mediating cardiovascular reflex transmission through the NTS.
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Poliacek I, Jakus J, Simera M, Veternik M, Plevkova J. Control of coughing by medullary raphé. PROGRESS IN BRAIN RESEARCH 2014; 212:277-95. [DOI: 10.1016/b978-0-444-63488-7.00014-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Teran FA, Massey CA, Richerson GB. Serotonin neurons and central respiratory chemoreception: where are we now? PROGRESS IN BRAIN RESEARCH 2014; 209:207-33. [PMID: 24746050 DOI: 10.1016/b978-0-444-63274-6.00011-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) neurons are widely considered to play an important role in central respiratory chemoreception. Although many studies in the past decades have supported this hypothesis, there had been concerns about its validity until recently. One recurring claim had been that 5-HT neurons are not consistently sensitive to hypercapnia in vivo. Another belief was that 5-HT neurons do not stimulate breathing; instead, they inhibit or modulate respiratory output. It was also believed by some that 5-HT neuron chemosensitivity is dependent on TASK channels, but mice with genetic deletion of TASK-1 and TASK-3 have a normal hypercapnic ventilatory response. This review explains why these principal arguments against the hypothesis are not supported by existing data. Despite repeated challenges, a large body of evidence now supports the conclusion that at least a subset of 5-HT neurons are central chemoreceptors.
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Affiliation(s)
- Frida A Teran
- St. Mary's University, One Camino Santa Maria, San Antonio, TX, USA
| | - Cory A Massey
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - George B Richerson
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; VAMC, Iowa City, IA, USA.
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Abstract
There is a growing public awareness that hormones can have a significant impact on most biological systems, including the control of breathing. This review will focus on the actions of two broad classes of hormones on the neuronal control of breathing: sex hormones and stress hormones. The majority of these hormones are steroids; a striking feature is that both groups are derived from cholesterol. Stress hormones also include many peptides which are produced primarily within the paraventricular nucleus of the hypothalamus (PVN) and secreted into the brain or into the circulatory system. In this article we will first review and discuss the role of sex hormones in respiratory control throughout life, emphasizing how natural fluctuations in hormones are reflected in ventilatory metrics and how disruption of their endogenous cycle can predispose to respiratory disease. These effects may be mediated directly by sex hormone receptors or indirectly by neurotransmitter systems. Next, we will discuss the origins of hypothalamic stress hormones and their relationship with the respiratory control system. This relationship is 2-fold: (i) via direct anatomical connections to brainstem respiratory control centers, and (ii) via steroid hormones released from the adrenal gland in response to signals from the pituitary gland. Finally, the impact of stress on the development of neural circuits involved in breathing is evaluated in animal models, and the consequences of early stress on respiratory health and disease is discussed.
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Affiliation(s)
- Mary Behan
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA.
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Mayer CA, Di Fiore JM, Martin RJ, Macfarlane PM. Vulnerability of neonatal respiratory neural control to sustained hypoxia during a uniquely sensitive window of development. J Appl Physiol (1985) 2013; 116:514-21. [PMID: 24371020 DOI: 10.1152/japplphysiol.00976.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The first postnatal weeks represent a period of development in the rat during which the respiratory neural control system may be vulnerable to aberrant environmental stressors. In the present study, we investigated whether sustained hypoxia (SH; 11% O2) exposure starting at different postnatal ages differentially modifies the acute hypoxic (HVR) and hypercapnic ventilatory response (HCVR). Three different groups of rat pups were exposed to 5 days of SH, starting at either postnatal age 1 (SH1-5), 11 (SH11-15), or 21 (SH21-25) days. Whole body plethysmography was used to assess the HVR and HCVR the day after SH exposure ended. The primary results indicated that 1) the HVR and HCVR of SH11-15 rats were absent or attenuated (respectively) compared with age-matched rats raised in normoxia; 2) there was a profoundly high (∼84% of pups) incidence of unexplained mortality in the SH11-15 rats; and 3) these phenomena were unique to the SH11-15 group with no comparable effect of the SH exposure on the HVR, HCVR, or mortality in the younger (SH1-5) or older (SH21-25) rats. These results share several commonalities with the risk factors thought to underlie the etiology of sudden infant death syndrome, including 1) a vulnerable neonate; 2) a critical period of development; and 3) an environmental stressor.
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Affiliation(s)
- C A Mayer
- Department of Pediatrics, Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, Ohio
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Iceman KE, Harris MB. A group of non-serotonergic cells is CO2-stimulated in the medullary raphé. Neuroscience 2013; 259:203-13. [PMID: 24333211 DOI: 10.1016/j.neuroscience.2013.11.060] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/13/2013] [Accepted: 11/30/2013] [Indexed: 01/22/2023]
Abstract
Serotonin/substance P synthesizing cells in the raphé nuclei of the brain are candidates for designation as central chemoreceptors that are stimulated by CO2/pH. We have previously demonstrated that these neurons are CO2-stimulated in situ. Evidence also suggests that CO2-inhibited raphé neurons recorded in vitro and in situ synthesize GABA. Unknown is whether there are other types of chemosensitive cells in the raphé. Here, we showed that a previously unrecognized pool of raphé neurons also exhibit chemosensitivity, and that they are not serotonergic. We used extracellular recording of individual raphé neurons in the unanesthetized juvenile rat in situ perfused decerebrate brainstem preparation to assess chemosensitivity of raphé neurons. Subsequent juxtacellular labeling of individually recorded cells, and immunohistochemistry for the serotonin synthesizing enzyme tryptophan hydroxylase and for neurokinin-1 receptor (NK1R; the receptor for substance P) indicated a group of CO2-stimulated cells that are not serotonergic, but express NK1R and are closely apposed to surrounding serotonergic cells. CO2-stimulated 5-HT and non-5-HT cells constitute distinct groups that have different firing characteristics and hypercapnic sensitivities. Non-5-HT cells fire faster and are more robustly stimulated by CO2 than are 5-HT cells. Thus, we have characterized a previously unrecognized type of CO2-stimulated medullary raphé neuron that is not serotonergic, but may receive input from neighboring serotonin/substance P synthesizing chemosensitive neurons. The potential network properties of the three types of chemosensitive raphé neurons (the present non-5-HT cells, serotonergic cells, and CO2-inhibited cells) remain to be elucidated.
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Affiliation(s)
- K E Iceman
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA; Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA.
| | - M B Harris
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA; Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775, USA
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Horner RL. Neural control of the upper airway: integrative physiological mechanisms and relevance for sleep disordered breathing. Compr Physiol 2013; 2:479-535. [PMID: 23728986 DOI: 10.1002/cphy.c110023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The various neural mechanisms affecting the control of the upper airway muscles are discussed in this review, with particular emphasis on structure-function relationships and integrative physiological motor-control processes. Particular foci of attention include the respiratory function of the upper airway muscles, and the various reflex mechanisms underlying their control, specifically the reflex responses to changes in airway pressure, reflexes from pulmonary receptors, chemoreceptor and baroreceptor reflexes, and postural effects on upper airway motor control. This article also addresses the determinants of upper airway collapsibility and the influence of neural drive to the upper airway muscles, and the influence of common drugs such as ethanol, sedative hypnotics, and opioids on upper airway motor control. In addition to an examination of these basic physiological mechanisms, consideration is given throughout this review as to how these mechanisms relate to integrative function in the intact normal upper airway in wakefulness and sleep, and how they may be involved in the pathogenesis of clinical problems such obstructive sleep apnea hypopnea.
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Iceman KE, Richerson GB, Harris MB. Medullary serotonin neurons are CO2 sensitive in situ. J Neurophysiol 2013; 110:2536-44. [PMID: 24047906 DOI: 10.1152/jn.00288.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Brainstem central chemoreceptors are critical to the hypercapnic ventilatory response, but their location and identity are poorly understood. When studied in vitro, serotonin-synthesizing (5-HT) neurons within the rat medullary raphé are intrinsically stimulated by CO2/acidosis. The contributions of these neurons to central chemosensitivity in vivo, however, are controversial. Lacking is documentation of CO2-sensitive 5-HT neurons in intact experimental preparations and understanding of their spatial and proportional distribution. Here we test the hypothesis that 5-HT neurons in the rat medullary raphé are sensitive to arterial hypercapnia. We use extracellular recording and hypercapnic challenge of spontaneously active medullary raphé neurons in the unanesthetized in situ perfused decerebrate brainstem preparation to assess chemosensitivity of individual cells. Juxtacellular labeling of a subset of recorded neurons and subsequent immunohistochemistry for the 5-HT-synthesizing enzyme tryptophan hydroxylase (TPH) identify or exclude this neurotransmitter phenotype in electrophysiologically characterized chemosensitive and insensitive cells. We show that the medullary raphé houses a heterogeneous population, including chemosensitive and insensitive 5-HT neurons. Of 124 recorded cells, 16 cells were juxtacellularly filled, visualized, and immunohistochemically identified as 5-HT synthesizing, based on TPH-immunoreactivity. Forty-four percent of 5-HT cells were CO2 stimulated (increased firing rate with hypercapnia), while 56% were unstimulated. Our results demonstrate that medullary raphé neurons are heterogeneous and clearly include a subset of 5-HT neurons that are excited by arterial hypercapnia. Together with data identifying intrinsically CO2-sensitive 5-HT neurons in vitro, these results support a role for such cells as central chemoreceptors in the intact system.
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Affiliation(s)
- Kimberly E Iceman
- Department of Biology and Wildlife, University of Alaska, Fairbanks, Alaska
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da Silva GS, Giusti H, Castro OW, Garcia-Cairasco N, Gargaglioni LH, Branco LG, Glass ML. Serotonergic neurons in the nucleus raphé obscurus are not involved in the ventilatory and thermoregulatory responses to hypoxia in adult rats. Respir Physiol Neurobiol 2013; 187:139-48. [DOI: 10.1016/j.resp.2013.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 03/21/2013] [Accepted: 04/08/2013] [Indexed: 11/25/2022]
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Corcoran AE, Richerson GB, Harris MB. Serotonergic mechanisms are necessary for central respiratory chemoresponsiveness in situ. Respir Physiol Neurobiol 2013; 186:214-20. [PMID: 23454177 DOI: 10.1016/j.resp.2013.02.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
Evidence from in vivo and in vitro experiments conclude that serotonin (5-HT) neurons are involved in and play an important role in central respiratory CO2/H(+) chemosensitivity. This study was designed to assess the importance of 5-HT neurons and 5-HT receptor activation in the frequency and amplitude components of the hypercapnic response of the respiratory network in the unanesthetized perfused in situ juvenile rat brainstem preparation that exhibits patterns of phrenic nerve discharge similar to breathing in vivo. Exposure to a hypercapnic perfusate increased phrenic burst frequency and/or amplitude, the neural correlates of breathing frequency and tidal volume in vivo. Hypercapnic responses were also assessed during exposure to ketanserin (5-HT2 receptor antagonist), and 8-OH-DPAT (inhibiting 5-HT neurons via 5-HT1A autoreceptors). Neither of these drugs substantially altered baseline activity, however, both abolished hypercapnic responses of the respiratory network. These data illustrate that 5-HT neurons and 5-HT receptor activation are not required for respiratory rhythm generation per se, but are critical for CO2 responses in situ, supporting the hypothesis that 5-HT neurons play an important role in central ventilatory chemosensitivity in vivo.
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Affiliation(s)
- Andrea E Corcoran
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
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Buchanan GF. Timing, sleep, and respiration in health and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 119:191-219. [PMID: 23899599 DOI: 10.1016/b978-0-12-396971-2.00008-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Breathing is perhaps the physiological function that is most vital to human survival. Without breathing and adequate oxygenation of tissues, life ceases. As would be expected for such a vital function, breathing occurs automatically, without the requirement of conscious input. Breathing is subject to regulation by a variety of factors including circadian rhythms and vigilance state. Given the need for breathing to occur continuously with little tolerance for interruption, it is not surprising that breathing is subject to both circadian phase-dependent and vigilance-state-dependent regulation. Similarly, the information regarding respiratory state, including blood-gas concentrations, can affect circadian timing and sleep-wake state. The exact nature of the interactions between breathing, circadian phase, and vigilance state can vary depending upon the species studied and the methodologies employed. These interactions between breathing, circadian phase, and vigilance state may have important implications for a variety of human diseases, including sleep apnea, asthma, sudden unexpected death in epilepsy, and sudden infant death syndrome.
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Affiliation(s)
- Gordon F Buchanan
- Department of Neurology, Yale University School of Medicine, New Haven, and Veteran's Affairs Medical Center, West Haven, Connecticut, USA
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Abstract
Central chemoreception traditionally refers to a change in ventilation attributable to changes in CO2/H(+) detected within the brain. Interest in central chemoreception has grown substantially since the previous Handbook of Physiology published in 1986. Initially, central chemoreception was localized to areas on the ventral medullary surface, a hypothesis complemented by the recent identification of neurons with specific phenotypes near one of these areas as putative chemoreceptor cells. However, there is substantial evidence that many sites participate in central chemoreception some located at a distance from the ventral medulla. Functionally, central chemoreception, via the sensing of brain interstitial fluid H(+), serves to detect and integrate information on (i) alveolar ventilation (arterial PCO2), (ii) brain blood flow and metabolism, and (iii) acid-base balance, and, in response, can affect breathing, airway resistance, blood pressure (sympathetic tone), and arousal. In addition, central chemoreception provides a tonic "drive" (source of excitation) at the normal, baseline PCO2 level that maintains a degree of functional connectivity among brainstem respiratory neurons necessary to produce eupneic breathing. Central chemoreception responds to small variations in PCO2 to regulate normal gas exchange and to large changes in PCO2 to minimize acid-base changes. Central chemoreceptor sites vary in function with sex and with development. From an evolutionary perspective, central chemoreception grew out of the demands posed by air versus water breathing, homeothermy, sleep, optimization of the work of breathing with the "ideal" arterial PCO2, and the maintenance of the appropriate pH at 37°C for optimal protein structure and function.
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Affiliation(s)
- Eugene Nattie
- Dartmouth Medical School, Department of Physiology, Lebanon, New Hampshire, USA.
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50
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Abstract
Central chemoreception traditionally refers to a change in ventilation attributable to changes in CO2/H(+) detected within the brain. Interest in central chemoreception has grown substantially since the previous Handbook of Physiology published in 1986. Initially, central chemoreception was localized to areas on the ventral medullary surface, a hypothesis complemented by the recent identification of neurons with specific phenotypes near one of these areas as putative chemoreceptor cells. However, there is substantial evidence that many sites participate in central chemoreception some located at a distance from the ventral medulla. Functionally, central chemoreception, via the sensing of brain interstitial fluid H(+), serves to detect and integrate information on (i) alveolar ventilation (arterial PCO2), (ii) brain blood flow and metabolism, and (iii) acid-base balance, and, in response, can affect breathing, airway resistance, blood pressure (sympathetic tone), and arousal. In addition, central chemoreception provides a tonic "drive" (source of excitation) at the normal, baseline PCO2 level that maintains a degree of functional connectivity among brainstem respiratory neurons necessary to produce eupneic breathing. Central chemoreception responds to small variations in PCO2 to regulate normal gas exchange and to large changes in PCO2 to minimize acid-base changes. Central chemoreceptor sites vary in function with sex and with development. From an evolutionary perspective, central chemoreception grew out of the demands posed by air versus water breathing, homeothermy, sleep, optimization of the work of breathing with the "ideal" arterial PCO2, and the maintenance of the appropriate pH at 37°C for optimal protein structure and function.
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Affiliation(s)
- Eugene Nattie
- Dartmouth Medical School, Department of Physiology, Lebanon, New Hampshire, USA.
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