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Nuding SC, Segers LS, Iceman K, O'Connor R, Dean JB, Valarezo PA, Shuman D, Solomon IC, Bolser DC, Morris KF, Lindsey BG. Hypoxia evokes a sequence of raphe-pontomedullary network operations for inspiratory drive amplification and gasping. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.07.566027. [PMID: 37986850 PMCID: PMC10659307 DOI: 10.1101/2023.11.07.566027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Hypoxia can trigger a sequence of breathing-related behaviors, from tachypnea to apneusis to apnea and gasping, an autoresuscitative behavior that, via large tidal volumes and altered intrathoracic pressure, can enhance coronary perfusion, carotid blood flow, and sympathetic activity, and thereby coordinate cardiac and respiratory functions. We tested the hypothesis that hypoxia-evoked gasps are amplified through a disinhibitory microcircuit within the inspiratory neuron chain and a distributed efference copy mechanism that generates coordinated gasp-like discharges concurrently in other circuits of the raphe-pontomedullary respiratory network. Data were obtained from 6 decerebrate, vagotomized, neuromuscularly-blocked, and artificially ventilated adult cats. Arterial blood pressure, phrenic nerve activity, end-tidal CO2, and other parameters were monitored. Hypoxia was produced by ventilation with a gas mixture of 5% O2 in nitrogen (N2). Neuron spike trains were recorded at multiple pontomedullary sites simultaneously and evaluated for firing rate modulations and short-time scale correlations indicative of functional connectivity. Experimental perturbations evoked reconfiguration of raphe-pontomedullary circuits during tachypnea, apneusis and augmented bursts, apnea, and gasping. The functional connectivity, altered firing rates, efference copy of gasp drive, and coordinated step increments in blood pressure reported here support a distributed brain stem network model for amplification and broadcasting of inspiratory drive during autoresuscitative gasping that begins with a reduction in inhibition by expiratory neurons and an initial loss of inspiratory drive during hypoxic apnea.
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Ahmadzadeh E, Dudink I, Walker DW, Sutherland AE, Pham Y, Stojanovska V, Polglase GR, Miller SL, Allison BJ. The medullary serotonergic centres involved in cardiorespiratory control are disrupted by fetal growth restriction. J Physiol 2023. [PMID: 37641535 DOI: 10.1113/jp284971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023] Open
Abstract
Fetal growth restriction (FGR) is associated with cardiovascular and respiratory complications after birth and beyond. Despite research showing a range of neurological changes following FGR, little is known about how FGR affects the brainstem cardiorespiratory control centres. The primary neurons that release serotonin reside in the brainstem cardiorespiratory control centres and may be affected by FGR. At two time points in the last trimester of sheep brain development, 110 and 127 days of gestation (0.74 and 0.86 of gestation), we assessed histopathological alterations in the brainstem cardiorespiratory control centres of the pons and medulla in early-onset FGR versus control fetal sheep. The FGR cohort were hypoxaemic and asymmetrically growth restricted. Compared to the controls, the brainstem of FGR fetuses exhibited signs of neuropathology, including elevated cell death and reduced cell proliferation, grey and white matter deficits, and evidence of oxidative stress and neuroinflammation. FGR brainstem pathology was predominantly observed in the medullary raphé nuclei, hypoglossal nucleus, nucleus ambiguous, solitary tract and nucleus of the solitary tract. The FGR groups showed imbalanced brainstem serotonin and serotonin 1A receptor abundance in the medullary raphé nuclei, despite evidence of increased serotonin staining within vascular regions of placentomes collected from FGR fetuses. Our findings demonstrate both early and adaptive brainstem neuropathology in response to placental insufficiency. KEY POINTS: Early-onset fetal growth restriction (FGR) was induced in fetal sheep, resulting in chronic fetal hypoxaemia. Growth-restricted fetuses exhibit persistent neuropathology in brainstem nuclei, characterised by disrupted cell proliferation and reduced neuronal cell number within critical centres responsible for the regulation of cardiovascular and respiratory functions. Elevated brainstem inflammation and oxidative stress suggest potential mechanisms contributing to the observed neuropathological changes. Both placental and brainstem levels of 5-HT were found to be impaired following FGR.
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Affiliation(s)
- Elham Ahmadzadeh
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Ingrid Dudink
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - David W Walker
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Amy E Sutherland
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Yen Pham
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Vanesa Stojanovska
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
| | - Beth J Allison
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
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Su J, Meng Y, Fang Y, Sun L, Wang M, Liu Y, Zhao C, Dai L, Ouyang S. Role of raphe magnus 5-HT 1A receptor in increased ventilatory responses induced by intermittent hypoxia in rats. Respir Res 2022; 23:42. [PMID: 35241072 PMCID: PMC8892800 DOI: 10.1186/s12931-022-01970-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 02/22/2022] [Indexed: 11/11/2022] Open
Abstract
Background Intermittent hypoxia induces increased ventilatory responses in a 5-HT-dependent manner. This study aimed to explore that effect of raphe magnus serotonin 1A receptor (5-HT1A) receptor on the increased ventilatory responses induced by intermittent hypoxia. Methods Stereotaxic surgery was performed in adult male rats, and acute and chronic intermittent hypoxia models were established after recovery from surgery. The experimental group received microinjections of 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) into the raphe magnus nucleus (RMg). Meanwhile, the control group received microinjections of artificial cerebrospinal fluid instead of 8-OH-DPAT. Ventilatory responses were compared among the different groups of oxygen status. 5-HT expressions in the RMg region were assessed by immunohistochemistry after chronic intermittent hypoxia. Results Compared with the normoxia group, the acute intermittent hypoxia group exhibited higher ventilatory responses (e.g., shorter inspiratory time and higher tidal volume, frequency of breathing, minute ventilation, and mean inspiratory flow) (P < 0.05). 8-OH-DPAT microinjection partly weakened these changes in the acute intermittent hypoxia group. Further, compared with the acute intermittent hypoxia group, rats in chronic intermittent hypoxia group exhibited higher measures of ventilatory responses after 1 day of intermittent hypoxia (P < 0.05). These effects peaked after 3 days of intermittent hypoxia treatment and then decreased gradually. Moreover, these changes were diminished in the experimental group. 5-HT expression in the RMg region increased after chronic intermittent hypoxia, which was consistent with the changing trend of ventilatory responses. While activation of the 5-HT1A receptor in the RMg region alleviated this phenomenon. Conclusions The results indicate that RMg 5-HT1A receptor, via changing the expression level of 5-HT in the RMg region, is involved in the modulation of the increased ventilatory responses induced by intermittent hypoxia. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-022-01970-6.
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Affiliation(s)
- Jiao Su
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Yang Meng
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Yifei Fang
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Linge Sun
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Mengge Wang
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Yanjun Liu
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Chunling Zhao
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China
| | - Liping Dai
- Henan Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Henan, 450052, China
| | - Songyun Ouyang
- Department of Respiratory and Sleep Medicine, First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe East Road, Erqi District, Zhengzhou, 450052, Henan, China.
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Palkovic B, Cook-Snyder D, Callison JJ, Langer TM, Nugent R, Stuth EA, Zuperku EJ, Stucke AG. Contribution of the caudal medullary raphe to opioid induced respiratory depression. Respir Physiol Neurobiol 2022; 299:103855. [PMID: 35124284 PMCID: PMC8897277 DOI: 10.1016/j.resp.2022.103855] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/10/2022] [Accepted: 01/30/2022] [Indexed: 01/31/2023]
Abstract
BACKGROUND Opioid-induced respiratory depression can be partially antagonized in the preBötzinger Complex and Parabrachial Nucleus/Kölliker-Fuse Complex. We hypothesized that additional opioid antagonism in the caudal medullary raphe completely reverses the opioid effect. METHODS In adult ventilated, vagotomized, decerebrate rabbits, we administrated remifentanil intravenously at "analgesic", "apneic", and "very high" doses and determined the reversal with sequential naloxone microinjections into the bilateral Parabrachial Nucleus/Kölliker-Fuse Complex, preBötzinger Complex, and caudal medullary raphe. In separate animals, we injected opioid antagonists into the raphe without intravenous remifentanil. RESULTS Sequential naloxone microinjections completely reversed respiratory rate depression from "analgesic" and "apneic" remifentanil, but not "very high" remifentanil concentrations. Antagonist injection into the caudal medullary raphe without remifentanil independently increased respiratory rate. CONCLUSIONS Opioid-induced respiratory depression results from a combined effect on the respiratory rhythm generator and respiratory drive. The effect in the caudal medullary raphe is complex as we also observed local antagonism of endogenous opioid receptor activation, which has not been described before.
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Trevizan-Baú P, Dhingra RR, Furuya WI, Stanić D, Mazzone SB, Dutschmann M. Forebrain projection neurons target functionally diverse respiratory control areas in the midbrain, pons, and medulla oblongata. J Comp Neurol 2020; 529:2243-2264. [PMID: 33340092 DOI: 10.1002/cne.25091] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/25/2020] [Accepted: 11/29/2020] [Indexed: 12/12/2022]
Abstract
Eupnea is generated by neural circuits located in the ponto-medullary brainstem, but can be modulated by higher brain inputs which contribute to volitional control of breathing and the expression of orofacial behaviors, such as vocalization, sniffing, coughing, and swallowing. Surprisingly, the anatomical organization of descending inputs that connect the forebrain with the brainstem respiratory network remains poorly defined. We hypothesized that descending forebrain projections target multiple distributed respiratory control nuclei across the neuroaxis. To test our hypothesis, we made discrete unilateral microinjections of the retrograde tracer cholera toxin subunit B in the midbrain periaqueductal gray (PAG), the pontine Kölliker-Fuse nucleus (KFn), the medullary Bötzinger complex (BötC), pre-BötC, or caudal midline raphé nuclei. We quantified the regional distribution of retrogradely labeled neurons in the forebrain 12-14 days postinjection. Overall, our data reveal that descending inputs from cortical areas predominantly target the PAG and KFn. Differential forebrain regions innervating the PAG (prefrontal, cingulate cortices, and lateral septum) and KFn (rhinal, piriform, and somatosensory cortices) imply that volitional motor commands for vocalization are specifically relayed via the PAG, while the KFn may receive commands to coordinate breathing with other orofacial behaviors (e.g., sniffing, swallowing). Additionally, we observed that the limbic or autonomic (interoceptive) systems are connected to broadly distributed downstream bulbar respiratory networks. Collectively, these data provide a neural substrate to explain how volitional, state-dependent, and emotional modulation of breathing is regulated by the forebrain.
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Affiliation(s)
- Pedro Trevizan-Baú
- The Florey Institute of Neuroscience and Mental Health, Discovery Neuroscience Theme, The University of Melbourne, Parkville, Victoria, Australia
| | - Rishi R Dhingra
- The Florey Institute of Neuroscience and Mental Health, Discovery Neuroscience Theme, The University of Melbourne, Parkville, Victoria, Australia
| | - Werner I Furuya
- The Florey Institute of Neuroscience and Mental Health, Discovery Neuroscience Theme, The University of Melbourne, Parkville, Victoria, Australia
| | - Davor Stanić
- The Florey Institute of Neuroscience and Mental Health, Discovery Neuroscience Theme, The University of Melbourne, Parkville, Victoria, Australia
| | - Stuart B Mazzone
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Mathias Dutschmann
- The Florey Institute of Neuroscience and Mental Health, Discovery Neuroscience Theme, The University of Melbourne, Parkville, Victoria, Australia
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Martvon L, Kotmanova Z, Dobrolubov B, Babalova L, Simera M, Veternik M, Pitts T, Jakus J, Poliacek I. Modulation of Cough Reflex by Gaba-Ergic Inhibition in Medullary Raphé of the Cat. Physiol Res 2020; 69:S151-S161. [PMID: 32228021 DOI: 10.33549/physiolres.934401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We studied the effects of GABA receptor agonists microinjections in medullary raphé on the mechanically induced tracheobronchial cough response in anesthetized, unparalyzed, spontaneously breathing cats. The results suggest that GABA-ergic inhibition significantly contributes to the regulation of cough reflex by action of both GABA(A) and GABA(B) receptors. The data are consistent with inhomogeneous occurrence of GABA-ergic neurons in medullary raphé and their different involvement in the cough reflex control. Cells within rostral nucleus raphéobscurus with dominant role of GABA(A) receptors and neurons of rostral nucleus raphépallidus and caudal nucleus raphémagnus with dominant role of GABA(B) receptors participate in regulation of cough expiratory efforts. These cough control elements are distinct from cough gating mechanism. GABA-ergic inhibition in the raphé caudal to obex had insignificant effect on cough. Contradictory findings for GABA, muscimol and baclofen administration in medullary raphé suggest involvement of coordinated activity of GABA on multiple receptors affecting raphé neurons and/or the local neuronal circuits in the raphé modulating cough motor drive.
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Affiliation(s)
- L Martvon
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University Bratislava, Martin,
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Cain BW, Reynolds T, Sarko DK. Superficial, suprahyoid, and infrahyoid neck musculature in naked mole-rats (Heterocephalus glaber): Relative size and potential contributions to independent movement of the lower incisors. J Morphol 2019; 280:1185-1196. [PMID: 31180596 DOI: 10.1002/jmor.21022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 11/06/2022]
Abstract
Naked mole-rats (Heterocephalus glaber) are fossorial, eusocial rodents that exhibit the unusual capability of moving their lower incisors independently in lateral and rostroventral directions. The evolution of this trait would presumably also involve concurrent alterations in neck musculature to support and control movements of the lower incisors. In order to assess morphological adaptations that might facilitate these movements, we performed detailed dissections of the neck musculature of adult naked mole-rats. In addition to characterizing attachment sites of superficial, suprahyoid, and infrahyoid musculature, we also quantified muscle mass and mandibular features thought to be associated with gape (condyle height, condyle length, and jaw length). Based on muscle attachment sites, the platysma myoides may contribute to lateral movement of the lower incisor and hemi-mandible in naked mole-rats. The large digastric muscle is likely to be a main contributor to rostroventral movement of each lower incisor. The geniohyoid and mylohyoid muscles also likely contribute to rostroventral movements of the lower incisors, and the mylohyoid may also produce lateral spreading of the hemi-mandibles. The transverse mandibular (intermandibularis) muscle likely serves to reposition the lower incisors back to a midline orientation following a movement.
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Affiliation(s)
- Blake W Cain
- Southern Illinois University School of Medicine, Department of Anatomy, Carbondale, Illinois
| | - Taylor Reynolds
- Southern Illinois University School of Medicine, Department of Anatomy, Carbondale, Illinois
| | - Diana K Sarko
- Southern Illinois University School of Medicine, Department of Anatomy, Carbondale, Illinois
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Szereda-Przestaszewska M, Kaczyńska K. Pharmacologically evoked apnoeas. Receptors and nervous pathways involved. Life Sci 2018; 217:237-242. [PMID: 30553870 DOI: 10.1016/j.lfs.2018.12.021] [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: 10/29/2018] [Revised: 12/05/2018] [Accepted: 12/12/2018] [Indexed: 01/07/2023]
Abstract
This review analyses the knowledge about the incidence of transient apnoeic spells, induced by substances which activate vagal chemically sensitive afferents. It considers the specificity and expression of appropriate receptors, and relevant research on pontomedullary circuits contributing to a cessation of respiration. Insight is gained into an excitatory drive of 5-HT1A serotonin receptors in overcoming opioid-induced respiratory inhibition.
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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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Das RK, Herr KB, Parkar A, Kubin L. Increased tongue use enhances 5-HT 2C receptor immunostaining in hypoglossal motor nucleus. Respir Physiol Neurobiol 2018; 260:105-113. [PMID: 30447306 DOI: 10.1016/j.resp.2018.11.005] [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: 08/02/2018] [Revised: 11/11/2018] [Accepted: 11/14/2018] [Indexed: 12/25/2022]
Abstract
Hypoglossal (XII) motoneurons are activated by type 2 receptors for serotonin (5-HT). This activation is especially strong during wakefulness which facilitates diverse motor functions of the tongue, including the maintenance of upper airway patency in obstructive sleep apnea (OSA) patients. We tested whether 5-HT2 receptor levels in the XII nucleus vary with intensity of tongue use. Three groups of rats were housed overnight under conditions of increasing oromotor activity: W-water available ad lib; S-sweetened water to stimulate drinking; S + O-sweetened water + oil applied on fur to increase grooming. After the exposures, immunostaining for 5-HT2C, but not 5-HT2A, receptors was higher in the XII nucleus in S + O than in W rats (65 ± 1.8 (SE) vs. 60 ± 2.0 arbitrary units; p = 0.008). In the medullary raphé obscurus region, the percentage of c-Fos-positive 5-HT cells was 13% higher (p = 0.03) in S + O than in W rats. The positive feedback between tongue use and 5-HT2C receptor immunostaining reveals a novel mechanism potentially relevant for OSA and neuromuscular disorders.
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Affiliation(s)
- Rajat K Das
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kate B Herr
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Anjum Parkar
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Leszek Kubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Ikoma Y, Kusumoto-Yoshida I, Yamanaka A, Ootsuka Y, Kuwaki T. Inactivation of Serotonergic Neurons in the Rostral Medullary Raphé Attenuates Stress-Induced Tachypnea and Tachycardia in Mice. Front Physiol 2018; 9:832. [PMID: 30050449 PMCID: PMC6050454 DOI: 10.3389/fphys.2018.00832] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/13/2018] [Indexed: 11/13/2022] Open
Abstract
The medullary raphé nuclei are involved in controlling cardiovascular, respiratory, and thermoregulatory functions, as well as mediating stress-induced tachycardia and hyperthermia. Although the serotonergic system of the medullary raphé has been suggested as the responsible entity, specific evidence has been insufficient. In the present study, we tested this possibility by utilizing an optogenetic approach. We used genetically modified mice [tryptophan hydroxylase 2 (Tph2); archaerhodopsin-T (ArchT) mice] in which ArchT, a green light-driven neuronal silencer, was selectively expressed in serotonergic neurons under the regulation of Tph2 promoters. We first confirmed that an intruder stress selectively activated medullary, but not dorsal or median raphé serotonergic neurons. This activation was suppressed by photo-illumination via a pre-implanted optical fiber, as evidenced by the decrease of a cellular activation marker protein in the neurons. Next, we measured electro cardiogram (ECG), respiration, body temperature (BT), and locomotor activity in freely moving mice during intruder and cage-drop stress tests, with and without photo-illumination. In the intruder test, photo inactivation of the medullary serotonergic neurons significantly attenuated tachycardia (362 ± 58 vs. 564 ± 65 bpm.min, n = 19, p = 0.002) and tachypnea (94 ± 82 vs. 361 ± 138 cpm.min, n = 9, p = 0.026), but not hyperthermia (1.0 ± 0.1 vs. 1.0 ± 0.1°C.min, n = 19, p = 0.926) or hyperlocomotion (17 ± 4 vs. 22 ± 4, arbitrary, n = 19, p = 0.089). Similar results were obtained from cage-drop stress testing. Finally, photo-illumination did not affect the basal parameters of the resting condition. We conclude that a subpopulation of serotonergic neurons in the medullary raphé specifically mediate stress-induced tachypnea and tachycardia, which have little involvement in the basal determination of respiratory frequency (Res) and heart rate (HR), specifically mediate stress-induced tachycardia and tachypnea.
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Affiliation(s)
- Yoko Ikoma
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Ikue Kusumoto-Yoshida
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Akihiro Yamanaka
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Youichirou Ootsuka
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Centre for Neuroscience, Discipline of Human Physiology, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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Zou Y, Wang W, Jin H, Nie X, Xu J, Liu Y, Kang J. The influence of 5-HT 1A receptors in the dorsal raphé nucleus on genioglossus activity. Respir Physiol Neurobiol 2017; 249:11-15. [PMID: 29208535 DOI: 10.1016/j.resp.2017.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 11/29/2022]
Abstract
Genioglossus activity maintains the patency of the upper airway. 5-HT neurons in the raphe nucleus regulate genioglossus activity. In order to study the influence of 5-HT1A receptors in dorsal raphé nucleus (DRN) on genioglossus EMG during normoxia, adult male Wistar rats were randomly divided into four groups: the artificial cerebrospinal fluid group (ACSF group), the low-concentration of 5-HT1A receptors agonist 8-OH-DPAT group (0.1 mM group), the mid-concentration 8-OH-DPAT group (0.4 mM group) and the high-concentration 8-OH-DPAT group (1.0 mM group). Rats received 0.1 μl ACSF/8-OH-DPAT microinjections into the DRN. EMG activity of the genioglossus was recorded at 5 min, 15 min and 30 min after microinjection. In three 8-OH-DPAT groups, genioglossus EMG activity significantly decreased at 5 min after microinjection and persisted for 30 min. The significantly decreased EMG activity was more pronounced in the mid- and high-concentration groups than in the low-concentration group, indicating that 5-HT1A receptors in the DRN could rapidly and continuously inhibit genioglossus EMG activity during normoxia.
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Affiliation(s)
- Ying Zou
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
| | - Wei Wang
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China.
| | - Hongyu Jin
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
| | - Xinshi Nie
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
| | - Jiahuan Xu
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
| | - Ying Liu
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
| | - Jian Kang
- Institute of Respiratory Disease, The First Hospital of China Medical University, Shenyang City, China
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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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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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Differential respiratory control of the upper airway and diaphragm muscles induced by 5-HT1A receptor ligands. Sleep Breath 2011; 16:135-47. [PMID: 21221824 DOI: 10.1007/s11325-010-0466-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/29/2010] [Accepted: 12/21/2010] [Indexed: 12/18/2022]
Abstract
BACKGROUND Serotonin (5-HT) has a role in respiratory function and dysfunction. Although 5-HT affects respiratory drive to both phrenic and cranial motoneurons, relatively little is known about the role of 5-HT receptor subtypes in the control of upper airway muscle (UAM) respiratory activity. MATERIALS AND METHODS Here, we performed central injections of 5-HT1A agonist (8-OHDPAT) or antagonist (WAY100635) in anesthetized rats and analyzed changes in the electromyographic activity of several UAM and other cardiorespiratory parameters. We also compared the pattern of Fos expression induced after central injection of a control solution or 8-OHDPAT. RESULTS Results showed that 8-OHDPAT induced a robust increase in UAM activity, associated with either tachypnea under volatile anesthesia or bradypnea under liquid anesthesia. Injection of WAY100635 switched off UAM respiratory activity and led to bradypnea, suggesting a tonic excitatory role of endogenous 5-HT1A receptor activation. Co-injection of the agonist and the antagonist blocked the effects produced by each drug alone. Besides drug-induced changes in respiratory frequency, only slight increases in surface of diaphragm bursts were observed. Significant increases in Fos expression after 5-HT1A receptor activation were seen in the nucleus tractus solitarius, nucleus raphe pallidus, parapyramidal region, retrotrapezoid nucleus, lateral parabrachial, and Kölliker-Fuse nuclei. This restricted pattern of Fos expression likely identified the neural substrate responsible for the enhancement of UAM respiratory activity observed after 8-OHDPAT injection. CONCLUSIONS These findings suggest an important role for the 5-HT1A receptors in the neural control of upper airway patency and may be relevant to counteract pharyngeal atonia during obstructive sleep apneas.
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Garcia AJ, Zanella S, Koch H, Doi A, Ramirez JM. Chapter 3--networks within networks: the neuronal control of breathing. PROGRESS IN BRAIN RESEARCH 2011; 188:31-50. [PMID: 21333801 DOI: 10.1016/b978-0-444-53825-3.00008-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Breathing emerges through complex network interactions involving neurons distributed throughout the nervous system. The respiratory rhythm generating network is composed of micro networks functioning within larger networks to generate distinct rhythms and patterns that characterize breathing. The pre-Bötzinger complex, a rhythm generating network located within the ventrolateral medulla assumes a core function without which respiratory rhythm generation and breathing cease altogether. It contains subnetworks with distinct synaptic and intrinsic membrane properties that give rise to different types of respiratory rhythmic activities including eupneic, sigh, and gasping activities. While critical aspects of these rhythmic activities are preserved when isolated in in vitro preparations, the pre-Bötzinger complex functions in the behaving animal as part of a larger network that receives important inputs from areas such as the pons and parafacial nucleus. The respiratory network is also an integrator of modulatory and sensory inputs that imbue the network with the important ability to adapt to changes in the behavioral, metabolic, and developmental conditions of the organism. This review summarizes our current understanding of these interactions and relates the emerging concepts to insights gained in other rhythm generating networks.
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Affiliation(s)
- Alfredo J Garcia
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
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Upper airway dysfunction of Tau-P301L mice correlates with tauopathy in midbrain and ponto-medullary brainstem nuclei. J Neurosci 2010; 30:1810-21. [PMID: 20130190 DOI: 10.1523/jneurosci.5261-09.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Tauopathy comprises hyperphosphorylation of the microtubule-associated protein tau, causing intracellular aggregation and accumulation as neurofibrillary tangles and neuropil treads. Some primary tauopathies are linked to mutations in the MAPT gene coding for protein tau, but most are sporadic with unknown causes. Also, in Alzheimer's disease, the most frequent secondary tauopathy, neither the cause nor the pathological mechanisms and repercussions are understood. Transgenic mice expressing mutant Tau-P301L suffer cognitive and motor defects and die prematurely from unknown causes. Here, in situ electrophysiology in symptomatic Tau-P301L mice (7-8 months of age) revealed reduced postinspiratory discharges of laryngeal motor outputs that control laryngeal constrictor muscles. Under high chemical drive (hypercapnia), postinspiratory discharge was nearly abolished, whereas laryngeal inspiratory discharge was increased disproportionally. The latter may suggest a shift of postinspiratory laryngeal constrictor activity into inspiration. In vivo double-chamber plethysmography of Tau-P301L mice showed significantly reduced respiratory airflow but significantly increased chest movements during baseline breathing, but particularly in hypercapnia, confirming a significant increase in inspiratory resistive load. Histological analysis demonstrated hyperphosphorylated tau in brainstem nuclei, directly or indirectly involved in upper airway motor control (i.e., the Kölliker-Fuse, periaqueductal gray, and intermediate reticular nuclei). In contrast, young Tau-P301L mice did not show breathing disorders or brainstem tauopathy. Consequently, in aging Tau-P301L mice, progressive upper airway dysfunction is linked to progressive tauopathy in identified neural circuits. Because patients with tauopathy suffer from upper airway dysfunction, the Tau-P301L mice can serve as an experimental model to study disease-specific synaptic dysfunction in well defined functional neural circuits.
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