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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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Chaves T, Fazekas CL, Horváth K, Correia P, Szabó A, Török B, Bánrévi K, Zelena D. Stress Adaptation and the Brainstem with Focus on Corticotropin-Releasing Hormone. Int J Mol Sci 2021; 22:ijms22169090. [PMID: 34445795 PMCID: PMC8396605 DOI: 10.3390/ijms22169090] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/18/2021] [Accepted: 08/20/2021] [Indexed: 12/13/2022] Open
Abstract
Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, including CRH, might be co-localized in the brainstem nuclei. Here we focused on CRH as its role in stress regulation is well-known and widely accepted and other CRH neurons scattered along the brain may also complement the function of the PVN. Although CRH-positive cells are present on some parts of the brainstem, sometimes even in comparable amounts as in the PVN, not much is known about their contribution to stress adaptation. Based on the role of the Barrington’s nucleus in micturition and the inferior olivary complex in the regulation of fine motoric—as the main CRH-containing brainstem areas—we might assume that these areas regulate stress-induced urination and locomotion, respectively. Further studies are necessary for the field.
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Affiliation(s)
- Tiago Chaves
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Csilla Lea Fazekas
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Krisztina Horváth
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Pedro Correia
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Adrienn Szabó
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Bibiána Török
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Krisztina Bánrévi
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
| | - Dóra Zelena
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- Correspondence:
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Sabino JPJ, Oliveira LVDC, Soriano RN, Kwiatkoski M, Branco LGS, da Silva GSF. Role of hydrogen sulfide in ventilatory responses to hypercapnia in the medullary raphe of adult rats. Exp Physiol 2021; 106:1992-2001. [PMID: 34159656 DOI: 10.1113/ep089335] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 06/18/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? There is evidence that H2 S plays a role in the control of breathing: what are its actions on the ventilatory and thermoregulatory responses to hypercapnia via effects in the medullary raphe, a brainstem region that participates in the ventilatory adjustments to hypercapnia? What is the main finding and its importance? Hypercapnia increased the endogenous production of H2 S in the medullary raphe. Inhibition of endogenous H2 S attenuated the ventilatory response to hypercapnia in unanaesthetized rats, suggesting its excitatory action via the cystathionine β-synthase-H2 S pathway in the medullary raphe. ABSTRACT Hydrogen sulfide (H2 S) has been recently recognized as a gasotransmitter alongside carbon monoxide (CO) and nitric oxide (NO). H2 S seems to modulate the ventilatory and thermoregulatory responses to hypoxia and hypercapnia. However, the action of the H2 S in the medullary raphe (MR) on the ventilatory responses to hypercapnia remains to be elucidated. The present study aimed to assess the role of H2 S in the MR (a brainstem region that contains CO2 -sensitive cells and participates in the ventilatory adjustments to hypercapnia) in the ventilatory responses to hypercapnia in adult unanaesthetized Wistar rats. To do so, aminooxyacetic acid (AOA; a cystathionine β-synthase (CBS) enzyme inhibitor), propargylglycine (PAG; a cystathionine γ-lyase enzyme inhibitor) and sodium sulfide (Na2 S; an H2 S donor) were microinjected into the MR. Respiratory frequency (fR ), tidal volume (VT ), ventilation ( V ̇ E ), oxygen consumption ( V ̇ O 2 ) and body temperature (Tb ) were measured under normocapnic (room air) and hypercapnic (7% CO2 ) conditions. H2 S concentration within the MR was determined. Microinjection of the drugs did not affect fR , VT and V ̇ E during normocapnia when compared to the control group. However, the microinjection of AOA, but not PAG, attenuated fR and V ̇ E during hypercapnia in comparison to the vehicle group, but had no effects on Tb . In addition, we observed an increase in the endogenous production of H2 S in the MR during hypercapnia. Our findings indicate that endogenously produced H2 S in the MR plays an excitatory role in the ventilatory response to hypercapnia, acting through the CBS-H2 S pathway.
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Affiliation(s)
- João Paulo Jacob Sabino
- Department of Biophysics and Physiology, Graduate Program in Pharmaceutical Sciences, Federal University of Piaui, Teresina, PI, Brazil
| | - Lucas Vaz de Castro Oliveira
- Department of Biophysics and Physiology, Graduate Program in Pharmaceutical Sciences, Federal University of Piaui, Teresina, PI, Brazil
| | - Renato Nery Soriano
- Division of Physiology and Biophysics, Department of Basic Life Sciences, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil
| | | | - Luiz G S Branco
- Department of Morphology, Physiology and Basic Pathology, Dental School of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics, Institute of Biological Science Federal, University of Minas Gerais, Belo Horizonte, MG, Brazil
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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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Raphe Pallidus is Not Important to Central Chemoreception in a Rat Model of Parkinson’s Disease. Neuroscience 2018; 369:350-362. [DOI: 10.1016/j.neuroscience.2017.11.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 01/31/2023]
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Leirão IP, Silva CA, Gargaglioni LH, da Silva GSF. Hypercapnia-induced active expiration increases in sleep and enhances ventilation in unanaesthetized rats. J Physiol 2017; 596:3271-3283. [PMID: 28776683 DOI: 10.1113/jp274726] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 08/01/2017] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Expiratory muscles (abdominal and thoracic) can be recruited when respiratory drive increases under conditions of increased respiratory demand such as hypercapnia. Studying hypercapnia-induced active expiration in unanaesthetized rats importantly contributes to the understanding of how the control system is integrated in vivo in freely moving animals. In unanaesthetized rats, hypercapnia-induced active expiration was not always recruited either in wakefulness or in sleep, suggesting that additional factors influence the recruitment of active expiration. The pattern of abdominal muscle recruitment varied in a state-dependent manner with active expiration being more predominant in the sleep state than in quiet wakefulness. Pulmonary ventilation was enhanced in periods with active expiration compared to periods without it. ABSTRACT Expiration is passive at rest but becomes active through recruitment of abdominal muscles under increased respiratory drive. Hypercapnia-induced active expiration has not been well explored in unanaesthetized rats. We hypothesized that (i) CO2 -evoked active expiration is recruited in a state-dependent manner, i.e. differently in sleep or wakefulness, and (ii) recruitment of active expiration enhances ventilation, hence having an important functional role in meeting metabolic demand. To test these hypotheses, Wistar rats (280-330 g) were implanted with electrodes for EEG and electromyography EMG of the neck, diaphragm (DIA) and abdominal (ABD) muscles. Active expiratory events were considered as rhythmic ABDEMG activity interposed to DIAEMG . Animals were exposed to room air followed by hypercapnia (7% CO2 ) with EEG, EMG and ventilation ( V̇E ) recorded throughout the experimental protocol. No active expiration was observed during room air exposure. During hypercapnia, CO2 -evoked active expiration was predominantly recruited during non-rapid eye movement sleep. Its increased occurrence during sleep was evidenced by the decreased DIA-to-ADB ratio (1:1 ratio means that each DIA event is followed by an ABD event, indicating a high occurrence of ABD activity). Moreover, V̇E was also enhanced (P < 0.05) in periods with active expiration. V̇E had a positive correlation (P < 0.05) with the peak amplitude of ABDEMG activity. The data demonstrate strongly that hypercapnia-induced active expiration increases during sleep and provides an important functional role to support V̇E in conditions of increased respiratory demand.
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Affiliation(s)
- Isabela P Leirão
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University (FCAV-UNESP), Jaboticabal, SP, Brazil
| | - Carlos A Silva
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University (FCAV-UNESP), Jaboticabal, 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 Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University (FCAV-UNESP), Jaboticabal, SP, Brazil
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Andrzejewski K, Kaczyńska K, Zaremba M. Serotonergic system in hypoxic ventilatory response in unilateral rat model of Parkinson's disease. J Biomed Sci 2017; 24:24. [PMID: 28347345 PMCID: PMC5368902 DOI: 10.1186/s12929-017-0331-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/21/2017] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Malfunctioning of the serotonergic system in Parkinson's disease may contribute to non-motor symptoms such as respiratory complications. Thus the aim of our study was to investigate the role of serotonin 5-HT2 receptors in the modulation of normoxic breathing and the hypoxic ventilatory response (HVR) in rat model of Parkinson's disease. METHODS Wistar rats were lesioned unilaterally with double 6-hydroxydopamine (6-OHDA) injection to the right medial forebrain bundle (MFB). Before lesion and two weeks later animals were put in whole body plethysmography chamber and exposed to hypoxia (8% O2). Before hypoxic tests animals received intraperitoneal injections of DOI and ketanserin. Efficacy of lesion was confirmed by cylinder test, assessing limb use asymmetry. RESULTS Degeneration of the nigrostriatal pathway augmented response of tidal volume and minute ventilation to hypoxia. DOI administration in control and lesion state caused a significant rise in normoxic respiratory rate and minute ventilation. Yet, ventilatory response of these parameters to hypoxia was attenuated. Post-DOI magnitude of HVR in lesioned state was decreased in compare to pre-lesion control. Subsequent ketanserin injection reverted DOI-induced respiratory effects. We demonstrated that 6-OHDA treatment decreased the content of serotonin in the injured striatum and on both sides of the brainstem, leaving the concentration of noradrenaline on unchanged level. CONCLUSIONS These observations showed that damage of the nigrostriatal system initiates changes in the serotonergic system, confirmed by reduced concentration of serotonin in the striatum and brainstem, which affects the magnitude of respiratory response to hypoxia after activation of 5-HT2 receptors.
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Affiliation(s)
- Kryspin Andrzejewski
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Katarzyna Kaczyńska
- Laboratory of Respiration Physiology, Mossakowski Medical Research Centre Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Małgorzata Zaremba
- Department of Experimental and Clinical Pharmacology, Centre for Preclinical Research (CePT), Medical University of Warsaw, Warsaw, Poland
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Wang X, Guo R, Zhao W, Pilowsky PM. Medullary mediation of the laryngeal adductor reflex: A possible role in sudden infant death syndrome. Respir Physiol Neurobiol 2016; 226:121-7. [PMID: 26774498 DOI: 10.1016/j.resp.2016.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/08/2016] [Accepted: 01/10/2016] [Indexed: 10/22/2022]
Abstract
The laryngeal adductor reflex (LAR) is a laryngeal protective reflex. Vagal afferent polymodal sensory fibres that have cell bodies in the nodose ganglion, originate in the sub-glottal area of the larynx and upper trachea. These polymodal sensory fibres respond to mechanical or chemical stimuli. The central axons of these sensory vagal neurons terminate in the dorsolateral subnuclei of the tractus solitarius in the medulla oblongata. The LAR is a critical, reflex in the pathways that play a protective role in the process of ventilation, and the sychronisation of ventilation with other activities that are undertaken by the oropharyngeal systems including: eating, speaking and singing. Failure of the LAR to operate properly at any time after birth can lead to SIDS, pneumonia or death. Despite the critical nature of this reflex, very little is known about the central pathways and neurotransmitters involved in the management of the LAR and any disorders associated with its failure to act properly. Here, we review current knowledge concerning the medullary nuclei and neurochemicals involved in the LAR and propose a potential neural pathway that may facilitate future SIDS research.
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Affiliation(s)
- Xiaolu Wang
- Institute of Clinical Pharmacology, Qilu Hospital of Shandong University, Jinan, China
| | - Ruichen Guo
- Institute of Clinical Pharmacology, Qilu Hospital of Shandong University, Jinan, China
| | - Wenjing Zhao
- Heart Research Institute, University of Sydney,7 Eliza St., Newtown, Australia
| | - Paul M Pilowsky
- Heart Research Institute, University of Sydney,7 Eliza St., Newtown, Australia.
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da Silva GSF, Soriano RN, Kwiatkoski M, Giusti H, Glass ML, Branco LGS. Central hydrogen sulphide mediates ventilatory responses to hypercapnia in adult conscious rats. Acta Physiol (Oxf) 2014; 212:239-47. [PMID: 25042027 DOI: 10.1111/apha.12346] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 04/30/2014] [Accepted: 07/09/2014] [Indexed: 11/30/2022]
Abstract
AIM Hydrogen sulphide (H2S) is endogenously produced and plays an important role as a modulator of neuronal functions; however, its modulatory role in the central CO2 chemoreception is unknown. The aim of the present study was to assess the role of endogenously produced H2S in the ventilatory response to hypercapnia in adult conscious rats. METHODS Cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) inhibitors (aminooxyacetate: AOA and propargylglycine: PAG respectively) and a H2S donor (sodium sulphide: Na2S) were microinjected into the fourth ventricle (4V). Ventilation (V̇(E)), oxygen consumption (V̇O2) and body temperature were recorded before (room air) and during a 30-min CO2 exposure (hypercapnia, 7% CO2). Endogenous H2S levels were measured in the nucleus tractus solitarius (NTS). RESULTS Microinjection of Na2S (H2S donor), AOA (CBS inhibitor) or PAG (CSE inhibitor) did not affect baseline of the measured variables compared to control group (vehicle). In all experimental groups, hypercapnia elicited an increase in V̇(E). However, AOA microinjection, but not PAG, attenuated the ventilatory response to hypercapnia (P < 0.05), whereas Na2S elicited a slight, not significant, enhancement. Moreover, endogenous H2S levels were found higher in the NTS after hypercapnia (P < 0.05) compared to room air (normoxia) condition. CONCLUSION There are a few reports on the role of gaseous transmitters in the control of breathing. Importantly, the present data suggest that endogenous H2S via the CBS-H2S pathway mediates the ventilatory response to hypercapnia playing an excitatory role.
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Affiliation(s)
- G. S. F. da Silva
- Dental School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Sao Paulo Brazil
| | - R. N. Soriano
- Dental School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Sao Paulo Brazil
| | - M. Kwiatkoski
- Medical School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Brazil
| | - H. Giusti
- Medical School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Brazil
| | - M. L. Glass
- Medical School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Brazil
| | - L. G. S. Branco
- Dental School of Ribeirao Preto; University of Sao Paulo; Ribeirao Preto Sao Paulo Brazil
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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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