1
|
Yang T, Wang Z, Li J, Shan F, Huang QY. Cerebral Lactate Participates in Hypoxia-induced Anapyrexia Through its Receptor G Protein-coupled Receptor 81. Neuroscience 2024; 536:119-130. [PMID: 37979840 DOI: 10.1016/j.neuroscience.2023.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/25/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
Hypoxia-induced anapyrexia is thought to be a regulated decrease in body core temperature (Tcore), but the underlying mechanism remains unclear. Recent evidence suggests that lactate, a glycolysis product, could modulate neuronal excitability through the G protein-coupled receptor 81 (GPR81). The present study aims to elucidate the role of central lactate and GPR81 in a rat model of hypoxia-induced anapyrexia. The findings revealed that hypoxia (11.1% O2, 2 h) led to an increase in lactate in cerebrospinal fluid (CSF) and a decrease in Tcore. Injection of dichloroacetate (DCA, 5 mg/kg, 1 μL), a lactate production inhibitor, to the third ventricle (3 V), alleviated the increase in CSF lactate and the decrease in Tcore under hypoxia. Immunofluorescence staining showed GPR81 was expressed in the preoptic area of hypothalamus (PO/AH), the physiological thermoregulation integration center. Under normoxia, injection of GPR81 agonist 3-chloro-5-hydroxybenzoic acid (CHBA, 0.05 mg/kg, 1 μL) to the 3 V, reduced Tcore significantly. In addition, hypoxia led to a dramatic increase in tail skin temperature and a decrease in interscapular brown adipose tissue skin temperature. The number of c-Fos+ cells in the PO/AH increased after exposure to 11.1% O2 for 2 h, but administration of DCA to the 3 V blunted this response. Injection of CHBA to the 3 V also increased the number of c-Fos+ cells in the PO/AH under normoxia. In light of these, our research has uncovered the pivotal role of central lactate-GPR81 signaling in anapyrexia, thereby providing novel insights into the mechanism of hypoxia-induced anapyrexia.
Collapse
Affiliation(s)
- Tian Yang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China
| | - Zejun Wang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China
| | - Junxia Li
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Traumatic Shock and Transfusion, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing 400042, China
| | - Fabo Shan
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Army Occupational Disease, Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing 400042, China.
| | - Qing-Yuan Huang
- Department of Frigid Zone Medicine, College of High Altitude Military Medicine, Army Medical University, Chongqing 400038, China; Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Chongqing 400038, China; Key Laboratory of High Altitude Medicine, PLA, Chongqing 400038, China.
| |
Collapse
|
2
|
Guo H, Cheng L, Duolikun D, Yao Q. Aerobic Exercise Training Under Normobaric Hypoxic Conditions to Improve Glucose and Lipid Metabolism in Overweight and Obese Individuals: A Systematic Review and Meta-Analysis. High Alt Med Biol 2023; 24:312-320. [PMID: 38127802 DOI: 10.1089/ham.2022.0099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023] Open
Abstract
Guo, Hai, Linjie Cheng, Dilihumaier Duolikun, and Qiaoling Yao. Aerobic exercise training under normobaric hypoxic conditions to improve glucose and lipid metabolism in overweight and obese individuals: a systematic review and meta-analysis. High Alt Med Biol. 24:312-320, 2023. Background: Obesity is a critical public health issue around the world, reaching epidemic proportions in some countries. However, only a few studies have examined the effects of hypoxic training on metabolic parameters in an obese population. This systematic review and meta-analysis aimed to determine the effects of aerobic exercise training under normobaric hypoxic conditions versus normoxic training in improving glucose and lipid metabolism in obese individuals. Methods: A systematic search of PubMed, EMBASE, Web of Science, and Wan Fang databases (up to August 2021) was performed to identify randomized controlled trials (RCTs) of overweight or obese human subjects eligible for inclusion. Main study endpoints were changes in body mass index (BMI), waist/hip (W/H) ratio, leptin, blood glucose and insulin levels, as well as blood lipids between hypoxic and normoxic conditioning. Results: Fourteen RCTs with a total of 413 subjects qualified for inclusion. Pooled analyses revealed that BMI (d = 0.38), W/H ratio (d = 0), blood glucose (d = 0.01), and triglyceride (d = -2.27) were not significantly different between aerobic exercise training under hypoxic and normoxic conditions. However, significant differences were found in heart rate at rest (d = -4.50) between aerobic exercise training under hypoxic versus normoxic conditions. Conclusions: In conclusion, no significant benefits were noted in aerobic exercise training under hypoxic conditions over normoxic conditions in overweight or obese individuals. However, the maximum training heart rate mm was significantly higher under hypoxic conditions than under normoxic conditions. Future studies with larger samples controlling for exercise-related parameters, and addressing the potential modifying effects of level of hypoxia, sex, or age on the role of hypoxic exercise training are warranted. PROSPERO registration number: CRD42020221680.
Collapse
Affiliation(s)
- Hai Guo
- Department of Physiology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, China
- Department of Anesthesiology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
- Xinjiang Perioperative Organ Protection Laboratory, Urumqi, China
| | - Linjie Cheng
- Department of Physiology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, China
| | - Dilihumaier Duolikun
- Department of Physiology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, China
| | - Qiaoling Yao
- Department of Physiology, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi, China
- Xinjiang Key Laboratory of Molecular Biology for Endemic Diseases, Urumqi, China
- State Key Laboratory of Pathogenesis, Prevention and Treatment of High Incidence Diseases in Central Asia, Urumqi, China
| |
Collapse
|
3
|
Elhussiny MZ, Nishimura H, Tran PV, Haraguchi S, Gilbert ER, Cline MA, Bungo T, Furuse M, Chowdhury VS. Intracerebroventricular injection of taurine induces hypothermia through modifying monoaminergic pathways in chicks. Eur J Pharmacol 2022; 928:175092. [PMID: 35697149 DOI: 10.1016/j.ejphar.2022.175092] [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: 04/20/2022] [Revised: 05/23/2022] [Accepted: 06/08/2022] [Indexed: 11/27/2022]
Abstract
Brain monoamines are reported to regulate body temperature and food intake. The objective of this study was to investigate the mechanism of brain monoamine metabolism in taurine-induced hypothermia and appetite suppression. In Experiment 1, 5-day-old male Julia layer chicks (n = 10) were subjected to intracerebroventricular (ICV) injection with saline or taurine (5 μmol/10 μL). In Experiment 2, the chicks were ICV injected with saline, taurine, fusaric acid (dopamine-β-hydroxylase inhibitor: 558 nmol), or taurine with fusaric acid. In Experiment 3, the chicks were ICV injected with saline, taurine, para-chlorophenylalanine (PCPA, tryptophan hydroxylase inhibitor: 400 nmol), or taurine with PCPA. In Experiment 4, the chicks were ICV injected with saline, taurine, clorgyline (monoamine oxidase inhibitor: 81 nmol), or taurine with clorgyline. Central taurine lowered rectal temperature at 30 min post-injection and increased norepinephrine in the brainstem and its metabolite 3-methoxy-4-hydroxyphenylglycol in both the diencephalon and brainstem. Similarly, taurine treatment induced increases in serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid in the diencephalon. Fusaric acid completely and PCPA partially, but not clorgyline, attenuated taurine-induced hypothermia. The anorexigenic effect of taurine was partially attenuated by PCPA, but not fusaric acid nor clorgyline. In conclusion, central taurine activates dopamine-β-hydroxylase and tryptophan hydroxylase to produce norepinephrine and 5-HT, and then induces hypothermia, but 5-HT alone may be linked with taurine-induced anorexia in chicks.
Collapse
Affiliation(s)
- Mohamed Z Elhussiny
- Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan; Department of Animal & Poultry Behavior and Management, Faculty of Veterinary Medicine, Aswan University, Aswan, 81528, Egypt
| | - Haruka Nishimura
- Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Phuong V Tran
- Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Shogo Haraguchi
- Department of Biochemistry, Showa University School of Medicine, Tokyo, 142-8555, Japan
| | - Elizabeth R Gilbert
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061-0306, USA
| | - Mark A Cline
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061-0306, USA
| | - Takashi Bungo
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, 794-8555, Japan
| | - Mitsuhiro Furuse
- Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan
| | - Vishwajit S Chowdhury
- Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, 819-0395, Japan; Division for Experimental Natural Science, Faculty of Arts and Science, Kyushu University, Fukuoka, 819-0395, Japan.
| |
Collapse
|
4
|
Blessing W, McAllen R, McKinley M. Control of the Cutaneous Circulation by the Central Nervous System. Compr Physiol 2016; 6:1161-97. [PMID: 27347889 DOI: 10.1002/cphy.c150034] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The central nervous system (CNS), via its control of sympathetic outflow, regulates blood flow to the acral cutaneous beds (containing arteriovenous anastomoses) as part of the homeostatic thermoregulatory process, as part of the febrile response, and as part of cognitive-emotional processes associated with purposeful interactions with the external environment, including those initiated by salient or threatening events (we go pale with fright). Inputs to the CNS for the thermoregulatory process include cutaneous sensory neurons, and neurons in the preoptic area sensitive to the temperature of the blood in the internal carotid artery. Inputs for cognitive-emotional control from the exteroceptive sense organs (touch, vision, sound, smell, etc.) are integrated in forebrain centers including the amygdala. Psychoactive drugs have major effects on the acral cutaneous circulation. Interoceptors, chemoreceptors more than baroreceptors, also influence cutaneous sympathetic outflow. A major advance has been the discovery of a lower brainstem control center in the rostral medullary raphé, regulating outflow to both brown adipose tissue (BAT) and to the acral cutaneous beds. Neurons in the medullary raphé, via their descending axonal projections, increase the discharge of spinal sympathetic preganglionic neurons controlling the cutaneous vasculature, utilizing glutamate, and serotonin as neurotransmitters. Present evidence suggests that both thermoregulatory and cognitive-emotional control of the cutaneous beds from preoptic, hypothalamic, and forebrain centers is channeled via the medullary raphé. Future studies will no doubt further unravel the details of neurotransmitter pathways connecting these rostral control centers with the medullary raphé, and those operative within the raphé itself. © 2016 American Physiological Society. Compr Physiol 6:1161-1197, 2016.
Collapse
Affiliation(s)
- William Blessing
- Human Physiology, Centre for Neuroscience, Flinders University, Adelaide, S.A., Australia
| | - Robin McAllen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
| | - Michael McKinley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
| |
Collapse
|
5
|
Santiago HP, Leite LHR, Lima PMA, Rodovalho GV, Szawka RE, Coimbra CC. The improvement of exercise performance by physical training is related to increased hypothalamic neuronal activation. Clin Exp Pharmacol Physiol 2015; 43:116-24. [DOI: 10.1111/1440-1681.12507] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Henrique P Santiago
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Laura HR Leite
- Department of Physiology; Institute of Biological Sciences; Federal University of Juiz de Fora; Juiz de Fora Minas Gerais Brazil
| | - Paulo Marcelo A Lima
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Gisele V Rodovalho
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Raphael E Szawka
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Cândido C Coimbra
- Department of Physiology and Biophysics; Institute of Biological Sciences; Federal University of Minas Gerais; Belo Horizonte Minas Gerais Brazil
| |
Collapse
|
6
|
Osaka T. 2-Deoxy-D-glucose-induced hypothermia in anesthetized rats: Lack of forebrain contribution and critical involvement of the rostral raphe/parapyramidal regions of the medulla oblongata. Brain Res Bull 2015; 116:73-80. [PMID: 26146232 DOI: 10.1016/j.brainresbull.2015.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 06/26/2015] [Accepted: 06/29/2015] [Indexed: 01/14/2023]
Abstract
Systemic or central administration of 2-deoxy-d-glucose (2DG), a competitive inhibitor of glucose utilization, induces hypothermia in awake animals and humans. This response is mediated by the central nervous system, though the neural mechanism involved is largely unknown. In this study, I examined possible involvement of the forebrain, which contains the hypothalamic thermoregulatory center, and the medullary rostral raphe/parapyramidal regions (rRPa/PPy), which mediate hypoxia-induced heat-loss responses, in 2DG-induced hypothermia in urethane-chloralose-anesthetized, neuromuscularly blocked, artificially ventilated rats. The intravenous injection of 2DG (250mgkg(-1)) elicited an increase in tail skin temperature and decreases in body core temperature and the respiratory exchange ratio, though it did not induce any significant change in the metabolic rate. These results indicate that the hypothermic response was caused by an increase in heat loss, but not by a decrease in heat production and that it was accompanied by a decrease in carbohydrate utilization and/or an increase in lipid utilization as energy substrates. Complete surgical transection of the brainstem between the hypothalamus and the midbrain had no effect on the 2DG-induced hypothermic responses, suggesting that the hindbrain, but not the forebrain, was sufficient for the responses. However, pretreatment of the rRPa/PPy with the GABAA receptor blocker bicuculline methiodide, but not with vehicle saline, greatly attenuated the 2DG-induced responses, suggesting that the 2DG-induced hypothermia was mediated, at least in part, by GABAergic neurons in the hindbrain and activation of GABAA receptors on cutaneous sympathetic premotor neurons in the rRPa/PPy.
Collapse
Affiliation(s)
- Toshimasa Osaka
- Department of Nutritional Science, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku 162-8636, Japan.
| |
Collapse
|
7
|
Branco LG, Soriano RN, Steiner AA. Gaseous Mediators in Temperature Regulation. Compr Physiol 2014; 4:1301-38. [DOI: 10.1002/cphy.c130053] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
8
|
Hypoxia-induced hypothermia mediated by GABA in the rostral parapyramidal area of the medulla oblongata. Neuroscience 2014; 267:46-56. [PMID: 24607346 DOI: 10.1016/j.neuroscience.2014.02.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/04/2014] [Accepted: 02/22/2014] [Indexed: 11/20/2022]
Abstract
Hypoxia evokes a regulated decrease in the body core temperature (Tc) in a variety of animals. The neuronal mechanisms of this response include, at least in part, glutamatergic activation in the lateral preoptic area (LPO) of the hypothalamus. As the sympathetic premotor neurons in the medulla oblongata constitute a cardinal relay station in the descending neuronal pathway from the hypothalamus for thermoregulation, their inhibition can also be critically involved in the mechanisms of the hypoxia-induced hypothermia. Here, I examined the hypothesis that hypoxia-induced hypothermia is mediated by glutamate-responsive neurons in the LPO that activate GABAergic transmission in the rostral raphe pallidus (rRPa) and neighboring parapyramidal region (PPy) of the medulla oblongata in urethane-chloralose-anesthetized, neuromuscularly blocked, artificially ventilated rats. Unilateral microinjection of GABA (15nmol) into the rRPa and PPy regions elicited a prompt increase in tail skin temperature (Ts) and decreases in Tc, oxygen consumption rate (VO2), and heart rate. Next, when the GABAA receptor blocker bicuculline methiodide (bicuculline methiodide (BMI), 10pmol) alone was microinjected into the rRPa, it elicited unexpected contradictory responses: simultaneous increases in Ts, VO2 and heart rate and a decrease in Tc. Then, when BMI was microinjected bilaterally into the PPy, no direct effect on Ts was seen; and thermogenic and tachycardic responses were slight. However, pretreatment of the PPy with BMI, but not vehicle saline, greatly attenuated the hypothermic responses evoked by hypoxic (10%O2-90%N2, 5min) ventilation or bilateral microinjections of glutamate (5nmol, each side) into the LPO. The results suggest that hypoxia-induced hypothermia was mediated, at least in part, by the activation of GABAA receptors in the PPy.
Collapse
|
9
|
Casanova JP, Contreras M, Moya EA, Torrealba F, Iturriaga R. Effect of insular cortex inactivation on autonomic and behavioral responses to acute hypoxia in conscious rats. Behav Brain Res 2013; 253:60-7. [PMID: 23860120 DOI: 10.1016/j.bbr.2013.07.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/21/2013] [Accepted: 07/09/2013] [Indexed: 11/25/2022]
Abstract
The present work was aimed to evaluate the contribution of interoception to the autonomic and behavioral responses to hypoxia. To address this issue, we studied whether the inactivation of the primary interoceptive posterior insular cortex (pIC) may disrupt the autonomic and behavioral effects of hypoxia in conscious rats. Rats were implanted with telemetric transmitters and microinjection cannulae placed bilaterally in the pIC. After one week, rats were injected with bupivacaine (26.5μM 1μL/side) and saline (1μL/side) into the pIC, and exposed to hypoxia (∼6% O2) for 150s, and autonomic and behavioral responses were recorded. Hypoxia produces hypertension, tachycardia followed by bradycardia, and hypothermia. When O2 dropped to ∼8%, rats showed escape behavior. Baseline cardiovascular variables and the pattern of hypoxia-induced autonomic and behavioral responses were not disrupted by pIC inactivation. However, pIC inactivation produced a modest but significant temperature decrease, higher bradycardic and hypertensive responses to hypoxia, and a minimal delay in escape onset. In addition, we measured the hypoxia-induced Fos activation in the nucleus tractus solitarius (NTS), the periaqueductal gray matter (PAG) and the pIC, which are key components of the interoceptive pathway. Hypoxia increased the number of Fos-positive neurons in the NTS and PAG, but not in the pIC. Present results suggest that pIC is not involved in the hypoxia-induced behavioral response, which seems to be processed in the NTS and PAG, but has a role in the efferent control of autonomic changes coping with hypoxia.
Collapse
Affiliation(s)
- Jose Patricio Casanova
- Laboratorio de Neurobiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | | | | | | | | |
Collapse
|
10
|
Nasehi M, Ahmadzadeh O, Rezayof A, Zarrindast MR. Does CA1 dopaminergic system play a role in cholestasis induced hypothermia? PATHOPHYSIOLOGY 2013; 20:181-9. [DOI: 10.1016/j.pathophys.2013.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 08/05/2013] [Accepted: 08/08/2013] [Indexed: 01/08/2023] Open
|
11
|
Osaka T. Hypoxia-induced hypothermia mediated by the glutamatergic transmission in the lateral preoptic area. Neuroscience 2012; 226:73-80. [DOI: 10.1016/j.neuroscience.2012.09.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 09/09/2012] [Accepted: 09/11/2012] [Indexed: 10/27/2022]
|
12
|
Miot S, Voituron N, Sterlin A, Vigneault E, Morel L, Matrot B, Ramanantsoa N, Amilhon B, Poirel O, Lepicard E, Mestikawy SE, Hilaire G, Gallego J. The vesicular glutamate transporter VGLUT3 contributes to protection against neonatal hypoxic stress. J Physiol 2012; 590:5183-98. [PMID: 22890712 DOI: 10.1113/jphysiol.2012.230722] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Neonates respond to hypoxia initially by increasing ventilation, and then by markedly decreasing both ventilation (hypoxic ventilatory decline) and oxygen consumption (hypoxic hypometabolism). This latter process, which vanishes with age, reflects a tight coupling between ventilatory and thermogenic responses to hypoxia. The neurological substrate of hypoxic hypometabolism is unclear, but it is known to be centrally mediated, with a strong involvement of the 5-hydroxytryptamine (5-HT, serotonin) system. To clarify this issue, we investigated the possible role of VGLUT3, the third subtype of vesicular glutamate transporter. VGLUT3 contributes to glutamate signalling by 5-HT neurons, facilitates 5-HT transmission and is expressed in strategic regions for respiratory and thermogenic control. We therefore assumed that VGLUT3 might significantly contribute to the response to hypoxia. To test this possibility, we analysed this response in newborn mice lacking VGLUT3 using anatomical, biochemical, electrophysiological and integrative physiology approaches. We found that the lack of VGLUT3 did not affect the histological organization of brainstem respiratory networks or respiratory activity under basal conditions. However, it impaired respiratory responses to 5-HT and anoxia, showing a marked alteration of central respiratory control. These impairments were associated with altered 5-HT turnover at the brainstem level. Furthermore, under cold conditions, the lack of VGLUT3 disrupted the metabolic rate, body temperature, baseline breathing and the ventilatory response to hypoxia. We conclude that VGLUT3 expression is dispensable under basal conditions but is required for optimal response to hypoxic stress in neonates.
Collapse
Affiliation(s)
- Stéphanie Miot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, 75005 Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Leite LHR, Zheng H, Coimbra CC, Patel KP. Contribution of the paraventricular nucleus in autonomic adjustments to heat stress. Exp Biol Med (Maywood) 2012; 237:570-7. [PMID: 22619372 DOI: 10.1258/ebm.2011.011286] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We assessed the contribution of the paraventricular nucleus (PVN) in the heat stress-mediated changes in sympathetic nerve activity and blood flow redistribution from the core to the skin surface. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), and body and tail temperatures were recorded in anesthetized rats after bilateral microinjection of cerebrospinal fluid (CSF), lidocaine or NG-monomethyl-L-arginine (L-NMMA) into the PVN during heat stress. Heat stress was induced by a graded increase in the temperature of a heating pad for 30 min. Heat stimulus after blockade of the PVN with lidocaine resulted in a blunted RSNA response (ΔRSNA: 117.6 ± 17.0% versus 11.3 ± 7.3%), as well as blunted MAP and HR (ΔMAP: 22 ± 2 versus -0.04 ± 7.2 mmHg; ΔHR: 93.4 ± 9.3 versus 43.4 ± 18.8 bpm). Body temperature threshold for tail vasodilation was unaffected by lidocaine treatment. The increase in RSNA, MAP and HR due to heat stress in L-NMMA-treated rats reached similar levels as CSF-treated control rats. However, a higher body temperature threshold for tail vasodilation was observed after L-NMMA injection (37.3 ± 0.1 versus 37.8 ± 0.2 °C). In conclusion, an intact PVN contributes to an increase in renal sympathetic activity provoked by heat stress, resulting in cardiovascular adjustments that influence core blood redistribution to the periphery. Furthermore, during heat stress, the effect of the PVN on cutaneous vasodilation is dependent on a nitric oxide mechanism.
Collapse
Affiliation(s)
- Laura H R Leite
- Department of Physiology, Institute of Biological Sciences, Federal University of Juiz de Fora, 36036-900 Juiz de Fora, Minas Gerais, Brazil
| | | | | | | |
Collapse
|
14
|
Kwiatkoski M, Soriano RN, Francescato HDC, Batalhao ME, Coimbra TM, Carnio EC, Branco LGS. Hydrogen sulfide as a cryogenic mediator of hypoxia-induced anapyrexia. Neuroscience 2011; 201:146-56. [PMID: 22120434 DOI: 10.1016/j.neuroscience.2011.11.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 12/29/2022]
Abstract
Hypoxia causes a regulated decrease in body temperature (Tb), a response that has been aptly called anapyrexia, but the mechanisms involved are not completely understood. The roles played by nitric oxide (NO) and other neurotransmitters have been documented during hypoxia-induced anapyrexia, but no information exists with respect to hydrogen sulfide (H(2)S), a gaseous molecule endogenously produced by cystathionine β-synthase (CBS). We tested the hypothesis that H(2)S production is enhanced during hypoxia and that the gas acts in the anteroventral preoptic region (AVPO; the most important thermosensitive and thermointegrative region of the CNS) modulating hypoxia-induced anapyrexia. Thus, we assessed CBS and nitric oxide synthase (NOS) activities [by means of H(2)S and nitrite/nitrate (NO(x)) production, respectively] as well as cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) levels in the anteroventral third ventricle region (AV3V; where the AVPO is located) during normoxia and hypoxia. Furthermore, we evaluated the effects of pharmacological modifiers of the H(2)S pathway given i.c.v. or intra-AVPO. I.c.v. or intra-AVPO microinjection of CBS inhibitor caused no change in Tb under normoxia but significantly attenuated hypoxia-induced anapyrexia. During hypoxia there were concurrent increases in H(2)S production, which could be prevented by CBS inhibitor, indicating the endogenous source of the gas. cAMP concentration, but not cGMP and NO(x), correlated with CBS activity. CBS inhibition increased NOS activity, whereas H(2)S donor decreased NO(x) production. In conclusion, hypoxia activates H(2)S endogenous production through the CBS-H(2)S pathway in the AVPO, having a cryogenic effect. Moreover, the present data are consistent with the notion that the two gaseous molecules, H(2)S and NO, play a key role in mediating the drop in Tb caused by hypoxia and that a fine-balanced interplay between NOS-NO and CBS-H(2)S pathways takes place in the AVPO of rats exposed to hypoxia.
Collapse
Affiliation(s)
- M Kwiatkoski
- Medical School of Ribeirão Preto, 14049-900, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | | | | | | | | | | |
Collapse
|