1
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Jin FX, Wang Y, Li MN, Li RJ, Guo JT. Intestinal glucagon-like peptide-1: A new player associated with impaired counterregulatory responses to hypoglycaemia in type 1 diabetic mice. World J Diabetes 2024; 15:1764-1777. [DOI: 10.4239/wjd.v15.i8.1764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 06/03/2024] [Accepted: 07/05/2024] [Indexed: 07/25/2024] Open
Abstract
BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic reactions. However, the patho-genesis of hypoglycaemic counterregulation is still unclear. Glucagon-like peptide-1 (GLP-1) and its analogues have been used as adjunctive therapies for type 1 diabetes mellitus (T1DM). The role of GLP-1 in counterregulatory dys-function during hypoglycaemia in patients with T1DM has not been reported.
AIM To explore the impact of intestinal GLP-1 on impaired hypoglycaemic counterregulation in type 1 diabetic mice.
METHODS T1DM was induced in C57BL/6J mice using streptozotocin, followed by intraperitoneal insulin injections to create T1DM models with either a single episode of hypoglycaemia or recurrent episodes of hypoglycaemia (DH5). Immunofluorescence, Western blot, and enzyme-linked immunosorbent assay were employed to evaluate the influence of intestinal GLP-1 on the sympathetic-adrenal reflex and glucagon (GCG) secretion. The GLP-1 receptor agonist GLP-1(7-36) or the antagonist exendin (9-39) were infused into the terminal ileum or injected intraperitoneally to further investigate the role of intestinal GLP-1 in hypoglycaemic counterregulation in the model mice.
RESULTS The expression levels of intestinal GLP-1 and its receptor (GLP-1R) were significantly increased in DH5 mice. Consecutive instances of excess of intestinal GLP-1 weakens the sympathetic-adrenal reflex, leading to dysfunction of adrenal counterregulation during hypoglycaemia. DH5 mice showed increased pancreatic δ-cell mass, cAMP levels in δ cells, and plasma somatostatin concentrations, while cAMP levels in pancreatic α cells and plasma GCG levels decreased. Furthermore, GLP-1R expression in islet cells and plasma active GLP-1 levels were significantly increased in the DH5 group. Further experiments involving terminal ileal infusion and intraperitoneal injection in the model mice demonstrated that intestinal GLP-1 during recurrent hypoglycaemia hindered the secretion of the counterregulatory hormone GCG via the endocrine pathway.
CONCLUSION Excessive intestinal GLP-1 is strongly associated with impaired counterregulatory responses to hypoglycaemia, leading to reduced appetite and compromised secretion of adrenaline, noradrenaline, and GCG during hypo-glycaemia.
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Affiliation(s)
- Fang-Xin Jin
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Yan Wang
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Min-Ne Li
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Ru-Jiang Li
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Jun-Tang Guo
- Department of Pathological Physiology, Shandong Second Medical University, Weifang 261053, Shandong Province, China
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2
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Schwarz KG, Vicencio SC, Inestrosa NC, Villaseca P, Del Rio R. Autonomic nervous system dysfunction throughout menopausal transition: A potential mechanism underpinning cardiovascular and cognitive alterations during female ageing. J Physiol 2024; 602:263-280. [PMID: 38064358 DOI: 10.1113/jp285126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/24/2023] [Indexed: 01/16/2024] Open
Abstract
Cardiovascular diseases (CVD) and neurodegenerative disorders, such as Alzheimer's disease (AD), are highly prevalent conditions in middle-aged women that severely impair quality of life. Recent evidence suggests the existence of an intimate cross-talk between the heart and the brain, resulting from a complex network of neurohumoral circuits. From a pathophysiological perspective, the higher prevalence of AD in women may be explained, at least in part, by sex-related differences in the incidence/prevalence of CVD. Notably, the autonomic nervous system, the main heart-brain axis physiological orchestrator, has been suggested to play a role in the incidence of adverse cardiovascular events in middle-aged women because of decreases in oestrogen-related signalling during transition into menopause. Despite its overt relevance for public health, this hypothesis has not been thoroughly tested. Accordingly, in this review, we aim to provide up to date evidence supporting how changes in circulating oestrogen levels during transition to menopause may trigger autonomic dysfunction, thus promoting cardiovascular and cognitive decline in women. A main focus on the effects of oestrogen-mediated signalling at CNS structures related to autonomic regulation is provided, particularly on the role of oestrogens in sympathoexcitation. Improving the understanding of the contribution of the autonomic nervous system on the development, maintenance and/or progression of both cardiovascular and cognitive dysfunction during the transition to menopause should help improve the clinical management of elderly women, with the outcome being an improved life quality during the natural ageing process.
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Affiliation(s)
- Karla G Schwarz
- Laboratory of Cardiorespiratory Control, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Sinay C Vicencio
- Laboratory of Cardiorespiratory Control, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nibaldo C Inestrosa
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
| | - Paulina Villaseca
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
- Department of Cell Biology and Physiology, School of Medicine, University of Kansas Medical Center, Kansas City, KS, USA
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3
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Zhou L, Zhang Y, Cao G, Zhang C, Zheng C, Meng G, Lai Y, Zhou Z, Liu Z, Liu Z, Guo F, Dong X, Liang Z, Wang Y, Guo S, Zhou X, Jiang H, Yu L. Wireless Self-Powered Optogenetic System for Long-Term Cardiac Neuromodulation to Improve Post-MI Cardiac Remodeling and Malignant Arrhythmia. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205551. [PMID: 36698262 PMCID: PMC10037959 DOI: 10.1002/advs.202205551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Autonomic imbalance is an important characteristic of patients after myocardial infarction (MI) and adversely contributes to post-MI cardiac remodeling and ventricular arrhythmias (VAs). A previous study proved that optogenetic modulation could precisely inhibit cardiac sympathetic hyperactivity and prevent acute ischemia-induced VAs. Here, a wireless self-powered optogenetic modulation system is introduced, which achieves long-term precise cardiac neuromodulation in ambulatory canines. The wireless self-powered optical system based on a triboelectric nanogenerator is powered by energy harvested from body motion and realized the effective optical illumination that is required for optogenetic neuromodulation (ON). It is further demonstrated that long-term ON significantly mitigates MI-induced sympathetic remodeling and hyperactivity, and improves a variety of clinically relevant outcomes such as improves ventricular dysfunction, reduces infarct size, increases electrophysiological stability, and reduces susceptibility to VAs. These novel insights suggest that wireless ON holds translational potential for the clinical treatment of arrhythmia and other cardiovascular diseases related to sympathetic hyperactivity. Moreover, this innovative self-powered optical system may provide an opportunity to develop implantable/wearable and self-controllable devices for long-term optogenetic therapy.
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Affiliation(s)
- Liping Zhou
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Yuanzheng Zhang
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
- Hubei Yangtze Memory LaboratoriesKey Laboratory of Artificial Micro, and Nano‐structures of Ministry of EducationSchool of Physics and TechnologyWuhan UniversityWuhan430072P. R. China
| | - Gang Cao
- Biomedical CenterCollege of Veterinary MedicineHuazhong Agricultural UniversityWuhan430072P. R. China
| | - Chi Zhang
- Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan430072P. R. China
| | - Chen Zheng
- Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan430072P. R. China
| | - Guannan Meng
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Yanqiu Lai
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Zhen Zhou
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Zhihao Liu
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Zihan Liu
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Fuding Guo
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Xin Dong
- Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan430072P. R. China
| | - Zhizhuo Liang
- Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and TechnologyWuhan430072P. R. China
| | - Yueyi Wang
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Shishang Guo
- Hubei Yangtze Memory LaboratoriesKey Laboratory of Artificial Micro, and Nano‐structures of Ministry of EducationSchool of Physics and TechnologyWuhan UniversityWuhan430072P. R. China
| | - Xiaoya Zhou
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Hong Jiang
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
| | - Lilei Yu
- Department of CardiologyRenmin Hospital of Wuhan UniversityHubei Key Laboratory of Autonomic Nervous System ModulationCardiac Autonomic Nervous System Research Center of Wuhan UniversityTaikang Center for Life and Medical SciencesWuhan UniversityCardiovascular Research InstituteWuhan UniversityHubei Key Laboratory of CardiologyWuhan430060P. R. China
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4
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Toledo C, Andrade DC, Diaz-Jara E, Ortolani D, Bernal-Santander I, Schwarz KG, Ortiz FC, Marcus NJ, Oliveira LM, Takakura AC, Moreira TS, Del Rio R. Cardiorespiratory alterations following intermittent photostimulation of RVLM C1 neurons: Implications for long-term blood pressure, breathing and sleep regulation in freely moving rats. Acta Physiol (Oxf) 2022; 236:e13864. [PMID: 35959519 DOI: 10.1111/apha.13864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 01/29/2023]
Abstract
AIM Sympathoexcitation and sleep-disordered breathing are common contributors for disease progression. Catecholaminergic neurons from the rostral ventrolateral medulla (RVLM-C1) modulate sympathetic outflow and have anatomical projections to respiratory neurons; however, the contribution of highly selective activation of RVLM-C1 neurons on long-term autonomic and breathing (dys)regulation remains to be understood. METHODS To explore this relationship, a lentiviral vector carrying the light-sensitive cation channel channelrhodopsin-2 (LVV-PRSX8-ChR2-YFP) was unilaterally injected into the RVLM of healthy rats. On the contralateral side, LVV-PRSX8-ChR2-YFP was co-injected with a specific immunotoxin (DβH-SAP) targeted to eliminate C1 neurons. RESULTS Intermittent photostimulation of RVLM-C1 in vivo, in unrestrained freely moving rats, elicited long-term facilitation of the sympathetic drive, a rise in blood pressure and sympatho-respiratory coupling. In addition, photoactivation of RVLM-C1 induced long-lasting ventilatory instability, characterized by oscillations in tidal volume and increased breathing variability, but only during non-rapid eye movement sleep. These effects were not observed when photostimulation of the RVLM was performed in the presence of DβH-SAP toxin. CONCLUSIONS The finding that intermittent activation of RVLM-C1 neurons induces autonomic and breathing dysfunction suggest that episodic stimulation of RVLM-C1 may serve as a pathological substrate for the long-term development of cardiorespiratory disorders.
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Affiliation(s)
- Camilo Toledo
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - David C Andrade
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Fisiología y Medicina de Altura, Departamento Biomedico, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Esteban Diaz-Jara
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Domiziana Ortolani
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ignacio Bernal-Santander
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Karla G Schwarz
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernando C Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad, Autónoma de Chile, Santiago, Chile
| | - Noah J Marcus
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, Iowa, USA
| | - Luiz M Oliveira
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración (CARE), Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
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5
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Souza GMPR, Stornetta DS, Vitali AJ, Wildner H, Zeilhofer HU, Campbell JN, Abbott SBG. Chemogenetic activation of noradrenergic A5 neurons increases blood pressure and visceral sympathetic activity in adult rats. Am J Physiol Regul Integr Comp Physiol 2022; 323:R512-R531. [PMID: 35993562 PMCID: PMC9602699 DOI: 10.1152/ajpregu.00119.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/28/2022] [Accepted: 08/16/2022] [Indexed: 11/22/2022]
Abstract
In mammals, the pontine noradrenergic system influences nearly every aspect of central nervous system function. A subpopulation of pontine noradrenergic neurons, called A5, are thought to be important in the cardiovascular response to physical stressors, yet their function is poorly defined. We hypothesized that activation of A5 neurons drives a sympathetically mediated increase in blood pressure (BP). To test this hypothesis, we conducted a comprehensive assessment of the cardiovascular effects of chemogenetic stimulation of A5 neurons in male and female adult rats using intersectional genetic and anatomical targeting approaches. Chemogenetic stimulation of A5 neurons in freely behaving rats elevated BP by 15 mmHg and increased cardiac baroreflex sensitivity with a negligible effect on resting HR. Importantly, A5 stimulation had no detectable effect on locomotor activity, metabolic rate, or respiration. Under anesthesia, stimulation of A5 neurons produced a marked elevation in visceral sympathetic nerve activity (SNA) and no change in skeletal muscle SNA, showing that A5 neurons preferentially stimulate visceral SNA. Interestingly, projection mapping indicates that A5 neurons target sympathetic preganglionic neurons throughout the spinal cord and parasympathetic preganglionic neurons throughout in the brainstem, as well as the nucleus of the solitary tract, and ventrolateral medulla. Moreover, in situ hybridization and immunohistochemistry indicate that a subpopulation of A5 neurons coreleases glutamate and monoamines. Collectively, this study suggests A5 neurons are a central modulator of autonomic function with a potentially important role in sympathetically driven redistribution of blood flow from the visceral circulation to critical organs and skeletal muscle.
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Affiliation(s)
- George M P R Souza
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Daniel S Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Alexander J Vitali
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Hanns U Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - John N Campbell
- Department of Biology, University of Virginia, Charlottesville, Virginia
| | - Stephen B G Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
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6
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Koba S, Kumada N, Narai E, Kataoka N, Nakamura K, Watanabe T. A brainstem monosynaptic excitatory pathway that drives locomotor activities and sympathetic cardiovascular responses. Nat Commun 2022; 13:5079. [PMID: 36038592 PMCID: PMC9424289 DOI: 10.1038/s41467-022-32823-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 08/18/2022] [Indexed: 11/09/2022] Open
Abstract
Exercise including locomotion requires appropriate autonomic cardiovascular adjustments to meet the metabolic demands of contracting muscles, yet the functional brain architecture underlying these adjustments remains unknown. Here, we demonstrate brainstem circuitry that plays an essential role in relaying volitional motor signals, i.e., central command, to drive locomotor activities and sympathetic cardiovascular responses. Mesencephalic locomotor neurons in rats transmit central command-driven excitatory signals onto the rostral ventrolateral medulla at least partially via glutamatergic processes, to activate both somatomotor and sympathetic nervous systems. Optogenetic excitation of this monosynaptic pathway elicits locomotor and cardiovascular responses as seen during running exercise, whereas pathway inhibition suppresses the locomotor activities and blood pressure elevation during voluntary running without affecting basal cardiovascular homeostasis. These results demonstrate an important subcortical pathway that transmits central command signals, providing a key insight into the central circuit mechanism required for the physiological conditioning essential to maximize exercise performance.
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Affiliation(s)
- Satoshi Koba
- Division of Integrative Physiology, Tottori University Faculty of Medicine, Yonago, Japan.
| | - Nao Kumada
- Division of Integrative Physiology, Tottori University Faculty of Medicine, Yonago, Japan.,Division of Integrative Bioscience, Tottori University Graduate School of Medical Sciences, Yonago, Japan
| | - Emi Narai
- Division of Integrative Physiology, Tottori University Faculty of Medicine, Yonago, Japan
| | - Naoya Kataoka
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Nagoya University Institute for Advanced Research, Nagoya, Japan
| | - Kazuhiro Nakamura
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tatsuo Watanabe
- Division of Integrative Physiology, Tottori University Faculty of Medicine, Yonago, Japan
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7
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da Silva MP, Spiller PF, Paton JFR, Moraes DJA. Peripheral chemoreflex activation induces expiratory but not inspiratory excitation of C1 pre-sympathetic neurones of rats. Acta Physiol (Oxf) 2022; 235:e13853. [PMID: 35722749 DOI: 10.1111/apha.13853] [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: 03/30/2022] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/30/2022]
Abstract
AIMS Stimulation of peripheral chemoreceptors, as during hypoxia, increases breathing and respiratory-related sympathetic bursting. Activation of catecholaminergic C1 neurones induces sympathoexcitation, while its ablation reduces the chemoreflex sympathoexcitatory response. However, no study has determined the respiratory phase(s) in which the pre-sympathetic C1 neurones are recruited by peripheral chemoreceptor and whether C1 neurone activation affects all phases of respiratory modulation of sympathetic activity. We addressed these unknowns by testing the hypothesis that peripheral chemoreceptor activation excites pre-sympathetic C1 neurones during inspiration and expiration. METHODS Using the in situ preparation of rat, we made intracellular recordings from baroreceptive pre-sympathetic C1 neurones during peripheral chemoreflex stimulation. We optogenetically activated C1 neurones selectively and compared any respiratory-phase-related increases in sympathetic activity with that which occurs following stimulation of the peripheral chemoreflex. RESULTS Activation of peripheral chemoreceptors using cytotoxic hypoxia (potassium cyanide) increased the firing frequency of C1 neurones and both the frequency and amplitude of their excitatory post-synaptic currents during the phase of expiration only. In contrast, optogenetic stimulation of C1 neurones activates inspiratory neurones, which secondarily inhibit expiratory neurones, but produced comparable increases in sympathetic activity across all phases of respiration. CONCLUSION Our data reveal that the peripheral chemoreceptor-mediated expiratory-related sympathoexcitation is mediated through excitation of expiratory neurones antecedent to C1 pre-sympathetic neurones; these may be found in the Kölliker-Fuse nucleus. Despite peripheral chemoreceptor excitation of inspiratory neurones, these do not trigger C1 neurone-mediated increases in sympathetic activity. These studies provide compelling novel insights into the functional organization of respiratory-sympathetic neural networks.
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Affiliation(s)
- Melina P da Silva
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.,Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Pedro F Spiller
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julian F R Paton
- Manaaki Manawa, The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Davi J A Moraes
- School of Medicine of Ribeirão Preto, Department of Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil
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8
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Sobrinho CR, Milla BM, Soto-Perez J, Moreira TS, Mulkey DK. Histamine/H1 receptor signaling in the parafacial region increases activity of chemosensitive neurons and respiratory activity in rats. J Neurophysiol 2022; 128:218-228. [PMID: 35704395 DOI: 10.1152/jn.00015.2022] [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
Histaminergic neurons of the tuberomammillary nucleus (TMN) are pH-sensitive and contribute to CO2/H+-dependent behaviors including arousal and respiratory activity. TMN neurons project to several respiratory centers including the ventral parafacial region (pF) where chemosensitive retrotrapezoid (RTN) neurons are located, and since RTN neurons are an important source of CO2/H+-dependent respiratory drive, we wondered whether histamine contributes to RTN chemoreception. To test this, we characterized effects of histamine on mean arterial pressure (MAP) and diaphragm muscle activity (DIAEMG) in urethane-anaesthetized, vagotomized and artificially ventilated male Wistar rats. Unilateral injection of histamine (25 mM) in the pF increased DIAEMG amplitude without changing DIAEMG frequency and MAP. Bilateral pF injections of the H1 receptor antagonist diphenhydramine hydrochloride (DPH; 0.5 mM) decreased baseline DIAEMG amplitude and frequency and MAP. Despite the strong inhibitory effect of DPH on baseline breathing, the hypercapnic ventilatory response was preserved under these experimental conditions. At the cellular level, chemosensitive RTN neurons showed a dose-dependent excitatory response to histamine that was blunted by DPH and mimicked by the H1 receptor agonist 2-pyridylethylamine dihydrochloride (2PYEA) under both control conditions and when fast neurotransmitter receptors are blocked. We also tested effects of 2PYEA in the presence of serotonin, another wake-on neurotransmitter that activates RTN chemoreceptors partly by activation of Gq-coupled receptors. We found the response to 2PYEA was diminished in serotonin, suggesting RTN neurons have a limited capacity to respond to multiple Gq-coupled modulators. These results suggest histamine can modulate breathing at the pF level by a mechanism involving H1 receptors.
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Affiliation(s)
- Cleyton R Sobrinho
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil.,Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Brenda M Milla
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Jaseph Soto-Perez
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of Sao Paulo, Sao Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
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9
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Malheiros-Lima MR, Silva TM, Takakura AC, Moreira TS. A5 noradrenergic-projecting C1 neurons activate sympathetic and breathing outputs in anaesthetized rats. Exp Physiol 2021; 107:147-160. [PMID: 34813109 DOI: 10.1113/ep089691] [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: 04/20/2021] [Accepted: 11/16/2021] [Indexed: 12/18/2022]
Abstract
NEW FINDINGS What is the central question of this study? C1 neurons innervate pontine noradrenergic cell groups, including the A5 region: do A5 noradrenergic neurons contribute to the activation of sympathetic and respiratory responses produced by selective activation of the C1 group of neurons. What is the main finding and its importance? The increase in sympathetic and respiratory activities elicited by selective stimulation of C1 neurons is reduced after blockade of excitatory amino acid within the A5 region, suggesting that the C1-A5 pathway might be important for sympathetic-respiratory control. ABSTRACT Adrenergic C1 neurons innervate and excite pontine noradrenergic cell groups, including the ventrolateral pontine noradrenergic region (A5). Here, we tested the hypothesis that C1 activates A5 neurons through the release of glutamate and this effect is important for sympathetic and respiratory control. Using selective tools, we restricted the expression of channelrhodopsin2 under the control of the artificial promoter PRSx8 to C1 neurons (69%). Transduced catecholaminergic terminals within the A5 region are in contact with noradrenergic A5 neurons and the C1 terminals within the A5 region are predominantly glutamatergic. In a different group of animals, we performed retrograde lesion of C1 adrenergic neurons projecting to the A5 region with unilateral injection of the immunotoxin anti-dopamine β-hydroxylase-saporin (anti-DβH-SAP) directly into the A5 region during the hypoxic condition. As expected, hypoxia (8% O2 , 3 h) induced a robust increase in fos expression within the catecholaminergic C1 and A5 regions of the brainstem. Depletion of C1 cells projecting to the A5 regions reduced fos immunoreactivity induced by hypoxia within the C1 region. Physiological experiments showed that bilateral injection of kynurenic acid (100 mM) into the A5 region reduced the rise in mean arterial pressure, and sympathetic and phrenic nerve activities produced by optogenetic stimulation of C1 cells. In conclusion, the C1 neurons activate the ventrolateral pontine noradrenergic neurons (A5 region) possibly via the release of glutamate and might be important for sympathetic and respiratory outputs in anaesthetized rats.
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Affiliation(s)
- Milene R Malheiros-Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, SP, Brazil
| | - Talita M Silva
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, SP, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, SP, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, SP, Brazil
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10
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Wang ZM, Rodrigues ACZ, Messi ML, Delbono O. Aging Blunts Sympathetic Neuron Regulation of Motoneurons Synaptic Vesicle Release Mediated by β1- and α2B-Adrenergic Receptors in Geriatric Mice. J Gerontol A Biol Sci Med Sci 2021; 75:1473-1480. [PMID: 31956900 DOI: 10.1093/gerona/glaa022] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Indexed: 11/14/2022] Open
Abstract
This study was designed to determine whether and how the sympathetic nervous system (SNS) regulates motoneuron axon function and neuromuscular transmission in young (3-4-month) and geriatric (31-month) mice. Our approach included sciatic-peroneal nerve immunolabeling coregistration, and electrophysiological recordings in a novel mouse ex-vivo preparation, the sympathetic-peroneal nerve-lumbricalis muscle (SPNL). Here, the interaction between the motoneuron and SNS at the neuromuscular junction (NMJ) and muscle innervation reflect the complexity of the living mouse. Our data show that electrical stimulation of the sympathetic neuron at the paravertebral ganglia chain enhances motoneuron synaptic vesicle release at the NMJ in young mice, while in geriatric mice, this effect is blunted. We also found that blocking β-AR prevents the sympathetic neuron from increasing NMJ transmission. Immunofluorescence coexpression analysis of immunolabeled ARs with choline acetyltransferase-, tyrosine hydroxylase-, or calcitonin gene-related peptide immunoreactive axons showed that α2B-AR is found mainly in sympathetic neurons, β1-AR in sympathetic- and motor-neurons, and both decline significantly with aging. In summary, this study unveils the molecular substrate accounting for the influence of endogenous sympathetic neurons on motoneuron-muscle transmission in young mice and its decline with aging.
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Affiliation(s)
- Zhong-Min Wang
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Anna Carolina Zaia Rodrigues
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - María Laura Messi
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Osvaldo Delbono
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Neuroscience Program, Wake Forest School of Medicine, Winston-Salem, North Carolina.,The Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina
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11
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Ribeiro N, Martins Sá RW, Antunes VR. Depletion of C1 neurons attenuates the salt-induced hypertension in unanesthetized rats. Brain Res 2020; 1748:147107. [PMID: 32905820 DOI: 10.1016/j.brainres.2020.147107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 08/24/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023]
Abstract
High salt intake is able to evoke neuroendocrine and autonomic responses that include vasopressin release and sympathoexcitation resulting in increasing in the arterial blood pressure (BP). The C1 neurons are a specific population of catecholaminergic neurons located in the RVLM region and they control BP under homeostatic imbalance. Thus, here we hypothesized that the ablation of C1 neurons mitigate the high blood pressure induced by high-salt intake. To test this hypothesis, we injected anti-DβH-SAP saporin at the RVLM and monitored the BP in unanesthetized animals exposed to high salt intake of 2% NaCl solution for 7 days. The injection of anti-DβH-SAP into the RVLM depleted 80% of tyrosine hydroxylase-positive neurons (TH+ neurons) in the C1, 38% in the A5, and no significant reduction in the A1 region, when compared to control group (saline as vehicle). High salt intake elicited a significant increase in BP in the control group, while in the anti-DβH-SAP group the depletion of TH+ neurons prevents the salt-induced hypertension. Moreover, the low frequency component of systolic BP and pulse interval were increased by high-salt intake in control animals but not in anti-DβH-SAP group, which indirectly suggests that the increase in the BP is mediated by increase in sympathetic activity. In conclusion, our data show that hypertension induced by high-salt intake is dependent on C1 neurons.
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Affiliation(s)
- Natalia Ribeiro
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Renato W Martins Sá
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Vagner R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
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12
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Diz-Chaves Y, Herrera-Pérez S, González-Matías LC, Lamas JA, Mallo F. Glucagon-Like Peptide-1 (GLP-1) in the Integration of Neural and Endocrine Responses to Stress. Nutrients 2020; 12:nu12113304. [PMID: 33126672 PMCID: PMC7692797 DOI: 10.3390/nu12113304] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/14/2020] [Accepted: 10/27/2020] [Indexed: 12/20/2022] Open
Abstract
Glucagon like-peptide 1 (GLP-1) within the brain is produced by a population of preproglucagon neurons located in the caudal nucleus of the solitary tract. These neurons project to the hypothalamus and another forebrain, hindbrain, and mesolimbic brain areas control the autonomic function, feeding, and the motivation to feed or regulate the stress response and the hypothalamic-pituitary-adrenal axis. GLP-1 receptor (GLP-1R) controls both food intake and feeding behavior (hunger-driven feeding, the hedonic value of food, and food motivation). The activation of GLP-1 receptors involves second messenger pathways and ionic events in the autonomic nervous system, which are very relevant to explain the essential central actions of GLP-1 as neuromodulator coordinating food intake in response to a physiological and stress-related stimulus to maintain homeostasis. Alterations in GLP-1 signaling associated with obesity or chronic stress induce the dysregulation of eating behavior. This review summarized the experimental shreds of evidence from studies using GLP-1R agonists to describe the neural and endocrine integration of stress responses and feeding behavior.
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Affiliation(s)
- Yolanda Diz-Chaves
- CINBIO, Universidade de Vigo, Grupo FB3A, Laboratorio de Endocrinología, 36310 Vigo, Spain;
- Correspondence: (Y.D.-C.); (F.M.); Tel.: +34-(986)-130226 (Y.D.-C.); +34-(986)-812393 (F.M.)
| | - Salvador Herrera-Pérez
- CINBIO, Universidade de Vigo, Grupo FB3B, Laboratorio de Neurociencia, 36310 Vigo, Spain; (S.H.-P.); (J.A.L.)
| | | | - José Antonio Lamas
- CINBIO, Universidade de Vigo, Grupo FB3B, Laboratorio de Neurociencia, 36310 Vigo, Spain; (S.H.-P.); (J.A.L.)
| | - Federico Mallo
- CINBIO, Universidade de Vigo, Grupo FB3A, Laboratorio de Endocrinología, 36310 Vigo, Spain;
- Correspondence: (Y.D.-C.); (F.M.); Tel.: +34-(986)-130226 (Y.D.-C.); +34-(986)-812393 (F.M.)
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13
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Fernandes-Junior SA, Oliveira LM, Czeisler CM, Mo X, Roy S, Somogyi A, Zhang L, Moreira TS, Otero JJ, Takakura AC. Stimulation of retrotrapezoid nucleus Phox2b-expressing neurons rescues breathing dysfunction in an experimental Parkinson's disease rat model. Brain Pathol 2020; 30:926-944. [PMID: 32497400 DOI: 10.1111/bpa.12868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/17/2020] [Accepted: 05/11/2020] [Indexed: 01/10/2023] Open
Abstract
Emerging evidence from multiple studies indicates that Parkinson's disease (PD) patients suffer from a spectrum of autonomic and respiratory motor deficiencies in addition to the classical motor symptoms attributed to substantia nigra degeneration of dopaminergic neurons. Animal models of PD show a decrease in the resting respiratory rate as well as a decrease in the number of Phox2b-expressing retrotrapezoid nucleus (RTN) neurons. The aim of this study was to determine the extent to which substantia nigra pars compact (SNc) degeneration induced RTN biomolecular changes and to identify the extent to which RTN pharmacological or optogenetic stimulations rescue respiratory function following PD-induction. SNc degeneration was achieved in adult male Wistar rats by bilateral striatal 6-hydroxydopamine injection. For proteomic analysis, laser capture microdissection and pressure catapulting were used to isolate the RTN for subsequent comparative proteomic analysis and Ingenuity Pathway Analysis (IPA). The respiratory parameters were evaluated by whole-body plethysmography and electromyographic analysis of respiratory muscles. The results confirmed reduction in the number of dopaminergic neurons of SNc and respiratory rate in the PD-animals. Our proteomic data suggested extensive RTN remodeling, and that pharmacological or optogenetic stimulations of the diseased RTN neurons promoted rescued the respiratory deficiency. Our data indicate that despite neuroanatomical and biomolecular RTN pathologies, that RTN-directed interventions can rescue respiratory control dysfunction.
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Affiliation(s)
- Silvio A Fernandes-Junior
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil.,Department of Pathology, School of Medicine, The Ohio State University (OSU), Columbus, OH
| | - Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Catherine M Czeisler
- Department of Pathology, School of Medicine, The Ohio State University (OSU), Columbus, OH
| | - Xiaokui Mo
- Department of Biostatistics and Bioinformatics, The Ohio State University (OSU), Columbus, OH
| | - Sashwati Roy
- Departments of Surgery and Molecular and Cellular Biochemistry, The Ohio State University (OSU), Columbus, OH
| | - Arpad Somogyi
- Mass Spectrometry and Proteomics Facility, The Ohio State University (OSU), Columbus, OH
| | - Liewn Zhang
- Mass Spectrometry and Proteomics Facility, The Ohio State University (OSU), Columbus, OH
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - José J Otero
- Department of Pathology, School of Medicine, The Ohio State University (OSU), Columbus, OH
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
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14
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Menuet C, Connelly AA, Bassi JK, Melo MR, Le S, Kamar J, Kumar NN, McDougall SJ, McMullan S, Allen AM. PreBötzinger complex neurons drive respiratory modulation of blood pressure and heart rate. eLife 2020; 9:57288. [PMID: 32538785 PMCID: PMC7326498 DOI: 10.7554/elife.57288] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/14/2020] [Indexed: 12/14/2022] Open
Abstract
Heart rate and blood pressure oscillate in phase with respiratory activity. A component of these oscillations is generated centrally, with respiratory neurons entraining the activity of pre-sympathetic and parasympathetic cardiovascular neurons. Using a combination of optogenetic inhibition and excitation in vivo and in situ in rats, as well as neuronal tracing, we demonstrate that preBötzinger Complex (preBötC) neurons, which form the kernel for inspiratory rhythm generation, directly modulate cardiovascular activity. Specifically, inhibitory preBötC neurons modulate cardiac parasympathetic neuron activity whilst excitatory preBötC neurons modulate sympathetic vasomotor neuron activity, generating heart rate and blood pressure oscillations in phase with respiration. Our data reveal yet more functions entrained to the activity of the preBötC, with a role in generating cardiorespiratory oscillations. The findings have implications for cardiovascular pathologies, such as hypertension and heart failure, where respiratory entrainment of heart rate is diminished and respiratory entrainment of blood pressure exaggerated.
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Affiliation(s)
- Clément Menuet
- Department of Physiology, University of Melbourne, Victoria, Australia.,Institut de Neurobiologie de la Méditerranée, INMED UMR1249, INSERM, Aix-Marseille Université, Marseille, France
| | - Angela A Connelly
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Jaspreet K Bassi
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Mariana R Melo
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Sheng Le
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Jessica Kamar
- Department of Physiology, University of Melbourne, Victoria, Australia
| | - Natasha N Kumar
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, NSW, Australia
| | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Simon McMullan
- Faculty of Medicine & Health Sciences, Macquarie University, NSW, Australia
| | - Andrew M Allen
- Department of Physiology, University of Melbourne, Victoria, Australia.,Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
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15
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Su CK. State-dependent modulation of sympathetic firing by α 1-adrenoceptors requires constitutive PKC activity in the neonatal rat spinal cord. Auton Neurosci 2020; 227:102688. [PMID: 32502943 DOI: 10.1016/j.autneu.2020.102688] [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: 01/21/2020] [Revised: 04/10/2020] [Accepted: 05/15/2020] [Indexed: 01/02/2023]
Abstract
The central adrenergic and noradrenergic neurotransmitter systems diffusively affect the operation of the spinal neural network and dynamically gauge central sympathetic outflow. Using in vitro splanchnic nerve-thoracic spinal cord preparations as an experimental model, this study examined the intraspinal α1-adrenoceptor-meidated modulation of sympathetic firing behaviors. Several sympathetic single-fiber activities were simultaneously recorded. Application of phenylephrine (Phe, an α1-adrenoceptor agonist) increased, decreased or did not affect spontaneous firing. A log-log plot of the change ratios of the average firing rates (AFR) versus their basal AFR displays a linear data distribution. Thus, the heterogeneity in α1-adrenoceptor-mediated responses is well described by a power law function. Phe-induced power-law firing modulation (plFM) was sensitive to prazosin (Prz, an α1-adrenoceptor antagonist). Heparin (Hep, a competitive IP3 receptor blocker) and chelerythrine (Che, a protein kinase C inhibitor) also caused plFM. Phe-induced plFM persisted in the presence of Hep; however, it was occluded by Che pretreatment. Pair-wise analysis of single-fiber activities revealed synchronous sympathetic discharges. Application of Phe, Hep or Che suppressed synchronous discharges in fiber pairs with apparent correlated firing (ACF) and induced or potentiated synchronous discharges in those without or with minimal ACF. Thus, the basal activities of the sympathetic preganglionic neurons participate in determining the responses mediated by the activation of α1-adrenoceptors. This deterministic factor, which is intrinsic to spinal neural networks, helps the supraspinal adrenergic and noradrenergic systems differentially control their widely distributed neural targets.
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Affiliation(s)
- Chun-Kuei Su
- Department of Biotechnology, College of Life Science, Zhaoqing University, Zhaoqing, Guangdong, China; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
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16
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Malheiros-Lima MR, Silva JN, Souza FC, Takakura AC, Moreira TS. C1 neurons are part of the circuitry that recruits active expiration in response to the activation of peripheral chemoreceptors. eLife 2020; 9:52572. [PMID: 31971507 PMCID: PMC7010411 DOI: 10.7554/elife.52572] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Breathing results from the interaction of two distinct oscillators: the pre-Bötzinger Complex (preBötC), which drives inspiration; and the lateral parafacial region (pFRG), which drives active expiration. The pFRG is silent at rest and becomes rhythmically active during the stimulation of peripheral chemoreceptors, which also activates adrenergic C1 cells. We postulated that the C1 cells and the pFRG may constitute functionally distinct but interacting populations for controlling expiratory activity during hypoxia. We found in rats that: a) C1 neurons are activated by hypoxia and project to the pFRG region; b) active expiration elicited by hypoxia was blunted after blockade of ionotropic glutamatergic receptors at the level of the pFRG; and c) selective depletion of C1 neurons eliminated the active expiration elicited by hypoxia. These results suggest that C1 cells may regulate the respiratory cycle, including active expiration, under hypoxic conditions.
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Affiliation(s)
- Milene R Malheiros-Lima
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Josiane N Silva
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Felipe C Souza
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
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17
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Integration of hindbrain and carotid body mechanisms that control the autonomic response to cardiorespiratory and glucoprivic insults. Respir Physiol Neurobiol 2019; 265:83-91. [DOI: 10.1016/j.resp.2018.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 08/01/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023]
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18
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Farmer DGS, Pracejus N, Dempsey B, Turner A, Bokiniec P, Paton JFR, Pickering AE, Burguet J, Andrey P, Goodchild AK, McAllen RM, McMullan S. On the presence and functional significance of sympathetic premotor neurons with collateralized spinal axons in the rat. J Physiol 2019; 597:3407-3423. [DOI: 10.1113/jp277661] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/23/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- David G. S. Farmer
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Natasha Pracejus
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Bowen Dempsey
- Neuroscience Paris‐Saclay Institute (Neuro‐PSI) CNRS Gif‐Sur‐Yvette France
| | - Anita Turner
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
| | - Phillip Bokiniec
- Department of Neuroscience Max Delbrück Center for Molecular Medicine (MDC) Berlin‐Buch, Germany Neuroscience Research Center and Cluster of Excellence NeuroCure Charité‐Universitätsmedizin Berlin Germany
| | - Julian F. R. Paton
- Department of Physiology Faculty of Medical & Health Sciences University of Auckland Park Road Grafton Auckland New Zealand
| | - Anthony E. Pickering
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences University of Bristol Bristol UK
| | - Jasmine Burguet
- Institut Jean‐Pierre Bourgin INRA AgroParisTech CNRS Université Paris‐Saclay Versailles France
| | - Philippe Andrey
- Institut Jean‐Pierre Bourgin INRA AgroParisTech CNRS Université Paris‐Saclay Versailles France
| | - Ann K. Goodchild
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
| | - Robin M. McAllen
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Simon McMullan
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
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19
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Rodenkirch C, Liu Y, Schriver BJ, Wang Q. Locus coeruleus activation enhances thalamic feature selectivity via norepinephrine regulation of intrathalamic circuit dynamics. Nat Neurosci 2018; 22:120-133. [PMID: 30559472 PMCID: PMC6301066 DOI: 10.1038/s41593-018-0283-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 11/01/2018] [Indexed: 12/03/2022]
Abstract
We investigated locus coeruleus (LC) modulation of thalamic feature selectivity through reverse correlation analysis of single-unit recordings from different stages of the rat vibrissa pathway. LC activation increased feature selectivity, drastically improving thalamic information transmission. We found this improvement was dependent on both local activation of α-adrenergic receptors and modulation of T-type calcium channels in the thalamus and was not due to LC modulation of trigeminothalamic feedforward or corticothalamic feedback inputs. Tonic spikes with LC stimulation carried 3-times the information than did tonic spikes without LC stimulation. Modelling confirmed norepinephrine (NE) regulation of intrathalamic circuit dynamics led to the improved information transmission. Behavioral data demonstrated that LC activation increased the perceptual performance of animals performing tactile discrimination tasks through LC-NE optimization of thalamic sensory processing. These results suggest a new sub-dimension within the tonic mode in which brain state can optimize thalamic sensory processing through modulation of intrathalamic circuit dynamics.
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Affiliation(s)
- Charles Rodenkirch
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Yang Liu
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Brian J Schriver
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Qi Wang
- Department of Biomedical Engineering, Columbia University, New York, NY, USA.
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20
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Basting T, Xu J, Mukerjee S, Epling J, Fuchs R, Sriramula S, Lazartigues E. Glutamatergic neurons of the paraventricular nucleus are critical contributors to the development of neurogenic hypertension. J Physiol 2018; 596:6235-6248. [PMID: 30151830 PMCID: PMC6292814 DOI: 10.1113/jp276229] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 08/17/2018] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Recurrent periods of over-excitation in the paraventricular nucleus (PVN) of the hypothalamus could contribute to chronic over-activation of this nucleus and thus enhanced sympathetic drive. Stimulation of the PVN glutamatergic population utilizing channelrhodopsin-2 leads to an immediate frequency-dependent increase in baseline blood pressure. Partial lesions of glutamatergic neurons of the PVN (39.3%) result in an attenuated rise in blood pressure following Deoxycorticosterone acetate (DOCA)-salt treatment and reduced index of sympathetic activity. These data suggest that stimulation of PVN glutamatergic neurons is sufficient to cause autonomic dysfunction and drive the increase in blood pressure during hypertension. ABSTRACT Neuro-cardiovascular dysregulation leads to increased sympathetic activity and neurogenic hypertension. The paraventricular nucleus (PVN) of the hypothalamus is a key hub for blood pressure (BP) control, producing or relaying the increased sympathetic tone in hypertension. We hypothesize that increased central sympathetic drive is caused by chronic over-excitation of glutamatergic PVN neurons. We tested how stimulation or lesioning of excitatory PVN neurons in conscious mice affects BP, baroreflex and sympathetic activity. Glutamatergic PVN neurons were unilaterally transduced with channelrhodopsin-2 using an adeno-associated virus (CamKII-ChR2-eYFP-AAV2) in wildtype mice (n = 7) to assess the impact of acute stimulation of excitatory PVN neurons selectively on resting BP in conscious mice. Stimulation of the PVN glutamatergic population resulted in an immediate frequency-dependent (2, 10 and 20 Hz) increase in BP from baseline by ∼9 mmHg at 20 Hz stimulation (P < 0.001). Additionally, in vGlut2-cre mice glutamatergic neurons of the PVN were bilaterally lesioned utilizing a cre-dependent caspase (AAV2-flex-taCASP3-TEVp). Resting BP and urinary noradrenaline (norepinephrine) levels were then recorded in conscious mice before and after DOCA-salt hypertension. Partial lesions of glutamatergic neurons of the PVN (39.3%, P < 0.05) resulted in an attenuated rise in BP following DOCA-salt treatment (P < 0.05 at 7 day time point, n = 8). Noradrenaline levels as an index of sympathetic activity between the lesion and wildtype groups showed a significant reduction after DOCA-salt treatment in the lesioned animals (P < 0.05). These experiments suggest that stimulation of PVN glutamatergic neurons is sufficient to cause autonomic dysfunction and drive the increase in BP.
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Affiliation(s)
- Tyler Basting
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
| | - Jiaxi Xu
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
| | - Snigdha Mukerjee
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
| | - Joel Epling
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
| | - Robert Fuchs
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
| | - Srinivas Sriramula
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
- Department of Pharmacology and Toxicology, Brody School of MedicineEast Carolina UniversityGreenvilleNC27834USA
| | - Eric Lazartigues
- Department of Pharmacology and Experimental TherapeuticsLouisiana State University Health Sciences CenterNew OrleansLA70112USA
- Cardiovascular Center of ExcellenceLouisiana State University Health Sciences CenterNew OrleansLA70112USA
- Neuroscience Center of ExcellenceLouisiana State University Health Sciences CenterNew OrleansLA70112USA
- Southeast Louisiana Veterans Health Care SystemNew OrleansLAUSA
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Upregulation of Nav1.6 expression in the rostral ventrolateral medulla of stress-induced hypertensive rats. Hypertens Res 2018; 41:1013-1022. [PMID: 30287879 DOI: 10.1038/s41440-018-0105-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 04/06/2018] [Accepted: 04/09/2018] [Indexed: 02/07/2023]
Abstract
The rostral ventrolateral medulla (RVLM) plays a key role in mediating the development of stress-induced hypertension (SIH) by excitation and/or inhibition of sympathetic preganglionic neurons. The voltage-gated sodium channel Nav1.6 has been found to contribute to neuronal hyperexcitability. To examine the expression of Nav1.6 in the RVLM during SIH, a rat model was established by administering electric foot-shocks and noises. We found that Nav1.6 protein expression in the RVLM of SIH rats was higher than that of control rats, peaking at the tenth day of stress. Furthermore, we observed changes in blood pressure correlating with days of stress, with systolic blood pressure (SBP) found to reach a similarly timed peak at the tenth day of stress. Percentages of cells exhibiting colocalization of Nav1.6 with NeuN, a molecular marker of neurons, indicated a strong correlation between upregulation of Nav1.6 expression in NeuN-positive cells and SBP. The level of RSNA was significantly increased after 10 days of stress induction than control group. Compared with the SIHR, knockdown of Nav1.6 in RVLM of the SIHR decreased the level of SBP, heart rate (HR) and renal sympathetic nerve activity (RSNA). These results suggest that upregulated Nav1.6 expression within neurons in the RVLM of SIH rats may contribute to overactivation of the sympathetic system in response to SIH development.
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22
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Unravelling the intravenous and in situ vasopressin effects on the urinary bladder in anesthetized female rats: More than one vasopressin receptor subtype involved? Eur J Pharmacol 2018; 834:109-117. [DOI: 10.1016/j.ejphar.2018.07.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/02/2018] [Accepted: 07/13/2018] [Indexed: 01/26/2023]
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Koba S, Hanai E, Kumada N, Kataoka N, Nakamura K, Watanabe T. Sympathoexcitation by hypothalamic paraventricular nucleus neurons projecting to the rostral ventrolateral medulla. J Physiol 2018; 596:4581-4595. [PMID: 30019338 DOI: 10.1113/jp276223] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/02/2018] [Indexed: 01/19/2023] Open
Abstract
KEY POINTS Causal relationships between central cardiovascular pathways and sympathetic vasomotor tone have not been evidenced. This study aimed to verify the sympathoexcitatory role of hypothalamic paraventricular nucleus neurons that project to the rostral ventrolateral medulla (PVN-RVLM neurons). By using optogenetic techniques, we demonstrated that stimulation of PVN-RVLM glutamatergic neurons increased renal sympathetic nerve activity and arterial pressure via, at least in part, stimulation of RVLM C1 neurons in rats. This monosynaptic pathway may function in acute sympathetic adjustments to stressors and/or be a component of chronic sympathetic hyperactivity in pathological conditions such as heart failure. ABSTRACT The rostral ventrolateral medulla (RVLM), which is known to play an important role in regulating sympathetic vasomotor tone, receives axonal projections from the hypothalamic paraventricular nucleus (PVN). However, no studies have proved that excitation of the PVN neurons that send axonal projections to the RVLM (PVN-RVLM neurons) causes sympathoexcitation. This study aimed to directly examine the sympathoexcitatory role of PVN-RVLM neurons. Male rats received microinjections into the PVN with an adeno-associated virus (AAV) vector that encoded a hybrid of channelrhodopsin-2/1 with the reporter tdTomato (ChIEF-tdTomato), or into the RVLM with a retrograde AAV vector that encoded a channelrhodopsin with green fluorescent protein (ChR2-GFPretro ). Under anaesthesia with urethane and α-chloralose, photostimulation (473 nm wavelength) of PVN-RVLM neurons, achieved by laser illumination of either RVLM of ChIEF-tdTomato rats (n = 8) or PVN of ChR2-GFPretro rats (n = 4), elicited significant renal sympathoexcitation. Immunofluorescence confocal microscopy showed that RVLM adrenergic C1 neurons of ChIEF-tdTomato rats were closely associated with tdTomato-labelled, PVN-derived axons that contained vesicular glutamate transporter 2. In another subset of anaesthetized ChIEF-tdTomato rats (n = 6), the renal sympathoexcitation elicited by photostimulation of the PVN was suppressed by administering ionotropic glutamate receptor blockers into the RVLM. These results demonstrate that excitation of PVN-RVLM glutamatergic neurons leads to sympathoexcitation via, at least in part, stimulation of RVLM C1 neurons.
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Affiliation(s)
- Satoshi Koba
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori, 683-8503, Japan
| | - Eri Hanai
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori, 683-8503, Japan
| | - Nao Kumada
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori, 683-8503, Japan
| | - Naoya Kataoka
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Kazuhiro Nakamura
- Department of Integrative Physiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.,PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Tatsuo Watanabe
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori, 683-8503, Japan
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Huckstepp RTR, Cardoza KP, Henderson LE, Feldman JL. Distinct parafacial regions in control of breathing in adult rats. PLoS One 2018; 13:e0201485. [PMID: 30096151 PMCID: PMC6086409 DOI: 10.1371/journal.pone.0201485] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/15/2018] [Indexed: 11/29/2022] Open
Abstract
Recently, based on functional differences, we subdivided neurons juxtaposed to the facial nucleus into two distinct populations, the parafacial ventral and lateral regions, i.e., pFV and pFL. Little is known about the composition of these regions, i.e., are they homogenous or heterogeneous populations? Here, we manipulated their excitability in spontaneously breathing vagotomized urethane anesthetized adult rats to further characterize their role in breathing. In the pFL, disinhibition or excitation decreased breathing frequency (f) with a concomitant increase of tidal volume (VT), and induced active expiration; in contrast, reducing excitation had no effect. This result is congruent with pFL neurons constituting a conditional expiratory oscillator comprised of a functionally homogeneous set of excitatory neurons that are tonically suppressed at rest. In the pFV, disinhibition increased f with a presumptive reflexive decrease in VT; excitation increased f, VT and sigh rate; reducing excitation decreased VT with a presumptive reflexive increase in f. Therefore, the pFV, has multiple functional roles that require further parcellation. Interestingly, while hyperpolarization of the pFV reduces ongoing expiratory activity, no perturbation of pFV excitability induced active expiration. Thus, while the pFV can affect ongoing expiratory activity, presumably generated by the pFL, it does not appear capable of directly inducing active expiration. We conclude that the pFL contains neurons that can initiate, modulate, and sustain active expiration, whereas the pFV contains subpopulations of neurons that differentially affect various aspects of breathing pattern, including but not limited to modulation of ongoing expiratory activity.
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Affiliation(s)
- Robert T. R. Huckstepp
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Kathryn P. Cardoza
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lauren E. Henderson
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jack L. Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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Breathing responses produced by optogenetic stimulation of adrenergic C1 neurons are dependent on the connection with preBötzinger complex in rats. Pflugers Arch 2018; 470:1659-1672. [DOI: 10.1007/s00424-018-2186-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 07/11/2018] [Accepted: 07/20/2018] [Indexed: 01/14/2023]
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26
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Korsak A, Sheikhbahaei S, Machhada A, Gourine AV, Huckstepp RTR. The Role Of Parafacial Neurons In The Control Of Breathing During Exercise. Sci Rep 2018; 8:400. [PMID: 29321559 PMCID: PMC5762684 DOI: 10.1038/s41598-017-17412-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/24/2017] [Indexed: 02/07/2023] Open
Abstract
Neuronal cell groups residing within the retrotrapezoid nucleus (RTN) and C1 area of the rostral ventrolateral medulla oblongata contribute to the maintenance of resting respiratory activity and arterial blood pressure, and play an important role in the development of cardiorespiratory responses to metabolic challenges (such as hypercapnia and hypoxia). In rats, acute silencing of neurons within the parafacial region which includes the RTN and the rostral aspect of the C1 circuit (pFRTN/C1), transduced to express HM4D (Gi-coupled) receptors, was found to dramatically reduce exercise capacity (by 60%), determined by an intensity controlled treadmill running test. In a model of simulated exercise (electrical stimulation of the sciatic or femoral nerve in urethane anaesthetised spontaneously breathing rats) silencing of the pFRTN/C1 neurons had no effect on cardiovascular changes, but significantly reduced the respiratory response during steady state exercise. These results identify a neuronal cell group in the lower brainstem which is critically important for the development of the respiratory response to exercise and, determines exercise capacity.
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Affiliation(s)
- Alla Korsak
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Shahriar Sheikhbahaei
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Asif Machhada
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom.
| | - Robert T R Huckstepp
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom. .,School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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27
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Kumada N, Koba S, Hanai E, Watanabe T. Distribution of Fos-immunoreactive cells in the ventral part of rat medulla following voluntary treadmill exercise. Auton Neurosci 2017; 208:80-87. [PMID: 28967579 DOI: 10.1016/j.autneu.2017.09.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/09/2017] [Accepted: 09/19/2017] [Indexed: 02/02/2023]
Abstract
The ventral part of the medulla, which contains important cardiovascular regions, is reportedly activated during exercise. Nevertheless, it was uncertain which region(s) in the ventral medulla are specifically activated by exercise. The present study aimed to demonstrate a general pattern of exercise-specific distribution of excited neuronal cells in the rat ventral medulla. Via immunohistochemical experiments, we mapped tyrosine hydroxylase- and Fos-immunoreactive cells (TH-IR and Fos-IR cells, respectively) on rat medullary coronal sections following a bout of voluntary treadmill exercise, a comparative control period, or after pharmacologically induced-hypotension under anesthesia. In the ventral medulla at the rostrocaudal level adjacent, but not rostral or caudal, to the caudal edge of the facial nucleus, voluntary treadmill exercise induced significant (P<0.05) increases in Fos expression, similar to hypotension. The rostral ventrolateral medulla (RVLM), as compared with the rostral ventromedial medulla (RVMM), displayed a greater number of Fos-IR cells due to either exercise or hypotension. In the RVLM, either exercise or hypotension induced significant expression of Fos in both TH-IR and TH non-immunoreactive cells. In the caudal ventrolateral medulla (CVLM), hypotension, but not exercise, increased the ratio of Fos-IR cells in the TH-IR population. These findings demonstrate that RVLM adrenergic and non-adrenergic neurons are specifically excited by voluntary exercise in rats, while RVMM or CVLM neurons are not. We suggest that RVLM C1/non-C1 neurons are a major part of central circuitries underlying sympathetic adjustments to exercise.
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Affiliation(s)
- Nao Kumada
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan.; Division of Integrative Bioscience, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Sciences, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Satoshi Koba
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan..
| | - Eri Hanai
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan.; Division of Integrative Bioscience, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Sciences, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Tatsuo Watanabe
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
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28
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Jiang J, Cui H, Rahmouni K. Optogenetics and pharmacogenetics: principles and applications. Am J Physiol Regul Integr Comp Physiol 2017; 313:R633-R645. [PMID: 28794102 DOI: 10.1152/ajpregu.00091.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/18/2017] [Accepted: 08/05/2017] [Indexed: 12/29/2022]
Abstract
Remote and selective spatiotemporal control of the activity of neurons to regulate behavior and physiological functions has been a long-sought goal in system neuroscience. Identification and subsequent bioengineering of light-sensitive ion channels (e.g., channelrhodopsins, halorhodopsin, and archaerhodopsins) from the bacteria have made it possible to use light to artificially modulate neuronal activity, namely optogenetics. Recent advance in genetics has also allowed development of novel pharmacological tools to selectively and remotely control neuronal activity using engineered G protein-coupled receptors, which can be activated by otherwise inert drug-like small molecules such as the designer receptors exclusively activated by designer drug, a form of chemogenetics. The cutting-edge optogenetics and pharmacogenetics are powerful tools in neuroscience that allow selective and bidirectional modulation of the activity of defined populations of neurons with unprecedented specificity. These novel toolboxes are enabling significant advances in deciphering how the nervous system works and its influence on various physiological processes in health and disease. Here, we discuss the fundamental elements of optogenetics and chemogenetics approaches and some of the applications that yielded significant advances in various areas of neuroscience and beyond.
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Affiliation(s)
- Jingwei Jiang
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa; and
| | - Huxing Cui
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa; and.,Obesity Research and Educational Initiative, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa; .,Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa; and.,Obesity Research and Educational Initiative, University of Iowa Carver College of Medicine, Iowa City, Iowa
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29
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Rukhadze I, Carballo NJ, Bandaru SS, Malhotra A, Fuller PM, Fenik VB. Catecholaminergic A1/C1 neurons contribute to the maintenance of upper airway muscle tone but may not participate in NREM sleep-related depression of these muscles. Respir Physiol Neurobiol 2017; 244:41-50. [PMID: 28711601 DOI: 10.1016/j.resp.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 12/12/2022]
Abstract
Neural mechanisms of obstructive sleep apnea, a common sleep-related breathing disorder, are incompletely understood. Hypoglossal motoneurons, which provide tonic and inspiratory activation of genioglossus (GG) muscle (a major upper airway dilator), receive catecholaminergic input from medullary A1/C1 neurons. We aimed to determine the contribution of A1/C1 neurons in control of GG muscle during sleep and wakefulness. To do so, we placed injections of a viral vector into DBH-cre mice to selectively express the hMD4i inhibitory chemoreceptors in A1/C1 neurons. Administration of the hM4Di ligand, clozapine-N-oxide (CNO), in these mice decreased GG muscle activity during NREM sleep (F1,1,3=17.1, p<0.05); a similar non-significant decrease was observed during wakefulness. CNO administration had no effect on neck muscle activity, respiratory parameters or state durations. In addition, CNO-induced inhibition of A1/C1 neurons did not alter the magnitude of the naturally occurring depression of GG activity during transitions from wakefulness to NREM sleep. These findings suggest that A1/C1 neurons have a net excitatory effect on GG activity that is most likely mediated by hypoglossal motoneurons. However, the activity of A1/C1 neurons does not appear to contribute to NREM sleep-related inhibition of GG muscle activity, suggesting that A1/C1 neurons regulate upper airway patency in a state-independent manner.
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Affiliation(s)
- Irma Rukhadze
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.
| | - Nancy J Carballo
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Sathyajit S Bandaru
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California San Diego, La Jolla, CA, USA
| | - Patrick M Fuller
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Victor B Fenik
- Department of Veterans Affairs, Greater Los Angeles Healthcare System, Los Angeles, CA, USA; WebSience International, Los Angeles, CA, USA
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30
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Depletion of rostral ventrolateral medullary catecholaminergic neurons impairs the hypoxic ventilatory response in conscious rats. Neuroscience 2017; 351:1-14. [DOI: 10.1016/j.neuroscience.2017.03.031] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/19/2017] [Accepted: 03/20/2017] [Indexed: 02/07/2023]
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31
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Blood Pressure Regulation by the Rostral Ventrolateral Medulla in Conscious Rats: Effects of Hypoxia, Hypercapnia, Baroreceptor Denervation, and Anesthesia. J Neurosci 2017; 37:4565-4583. [PMID: 28363984 DOI: 10.1523/jneurosci.3922-16.2017] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/23/2017] [Accepted: 03/26/2017] [Indexed: 02/07/2023] Open
Abstract
Current understanding of the contribution of C1 neurons to blood pressure (BP) regulation derives predominantly from experiments performed in anesthetized animals or reduced ex vivo preparations. Here, we use ArchaerhodopsinT3.0 (ArchT) loss-of-function optogenetics to explore BP regulation by C1 neurons in intact, unanesthetized rats. Using a lentivirus that expresses ArchT under the Phox2b-activated promoter PRSx8 (PRSx8-ArchT), ∼65% of transduced neurons were C1 (balance retrotrapezoid nucleus, RTN). Other rats received CaMKII-ArchT3.0 AAV2 (CaMKII-ArchT), which transduced C1 neurons and larger numbers of unidentified glutamatergic and GABAergic cells. Under anesthesia, ArchT photoactivation reduced sympathetic nerve activity and BP and silenced/strongly inhibited most (7/12) putative C1 neurons. In unanesthetized PRSx8-ArchT-treated rats breathing room air, bilateral ArchT photoactivation caused a very small BP reduction that was only slightly larger under hypercapnia (6% FiCO2), but was greatly enhanced during hypoxia (10 and 12% FiO2), after sino-aortic denervation, or during isoflurane anesthesia. The degree of hypotension correlated with percentage of ArchT-transduced C1 neurons. ArchT photoactivation produced similar BP changes in CaMKII-ArchT-treated rats. Photoactivation in PRSX8-ArchT rats reduced breathing frequency (FR), whereas FR increased in CaMKII-ArchT rats. We conclude that the BP drop elicited by ArchT activation resulted from C1 neuron inhibition and was unrelated to breathing changes. C1 neurons have low activity under normoxia, but their activation is important to BP stability during hypoxia or anesthesia and contributes greatly to the hypertension caused by baroreceptor deafferentation. Finally, C1 neurons are marginally activated by hypercapnia and the large breathing stimulation caused by this stimulus has very little impact on resting BP.SIGNIFICANCE STATEMENT C1 neurons are glutamatergic/peptidergic/catecholaminergic neurons located in the medulla oblongata, which may operate as a switchboard for differential, behavior-appropriate activation of selected sympathetic efferents. Based largely on experimentation in anesthetized or reduced preparations, a rostrally located subset of C1 neurons may contribute to both BP stabilization and dysregulation (hypertension). Here, we used Archaerhodopsin-based loss-of-function optogenetics to explore the contribution of these neurons to BP in conscious rats. The results suggest that C1 neurons contribute little to resting BP under normoxia or hypercapnia, C1 neuron discharge is restrained continuously by arterial baroreceptors, and C1 neuron activation is critical to stabilize BP under hypoxia or anesthesia. This optogenetic approach could also be useful to explore the role of C1 neurons during specific behaviors or in hypertensive models.
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Menuet C, Le S, Dempsey B, Connelly AA, Kamar JL, Jancovski N, Bassi JK, Walters K, Simms AE, Hammond A, Fong AY, Goodchild AK, McMullan S, Allen AM. Excessive Respiratory Modulation of Blood Pressure Triggers Hypertension. Cell Metab 2017; 25:739-748. [PMID: 28215844 DOI: 10.1016/j.cmet.2017.01.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/09/2016] [Accepted: 01/28/2017] [Indexed: 02/07/2023]
Abstract
The etiology of hypertension, the world's biggest killer, remains poorly understood, with treatments targeting the established symptom, not the cause. The development of hypertension involves increased sympathetic nerve activity that, in experimental hypertension, may be driven by excessive respiratory modulation. Using selective viral and cell lesion techniques, we identify adrenergic C1 neurons in the medulla oblongata as critical for respiratory-sympathetic entrainment and the development of experimental hypertension. We also show that a cohort of young, normotensive humans, selected for an exaggerated blood pressure response to exercise and thus increased hypertension risk, has enhanced respiratory-related blood pressure fluctuations. These studies pinpoint a specific neuronal target for ameliorating excessive sympathetic activity during the developmental phase of hypertension and identify a group of pre-hypertensive subjects that would benefit from targeting these cells.
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Affiliation(s)
- Clément Menuet
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Sheng Le
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Bowen Dempsey
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Angela A Connelly
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jessica L Kamar
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Nikola Jancovski
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jaspreet K Bassi
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Keryn Walters
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Annabel E Simms
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Andrew Hammond
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Angelina Y Fong
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ann K Goodchild
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Simon McMullan
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Andrew M Allen
- Department of Physiology, University of Melbourne, Parkville, VIC 3010, Australia; Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia.
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Xie AX, Lee JJ, McCarthy KD. Ganglionic GFAP + glial Gq-GPCR signaling enhances heart functions in vivo. JCI Insight 2017; 2:e90565. [PMID: 28138563 DOI: 10.1172/jci.insight.90565] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The sympathetic nervous system (SNS) accelerates heart rate, increases cardiac contractility, and constricts resistance vessels. The activity of SNS efferent nerves is generated by a complex neural network containing neurons and glia. Gq G protein-coupled receptor (Gq-GPCR) signaling in glial fibrillary acidic protein-expressing (GFAP+) glia in the central nervous system supports neuronal function and regulates neuronal activity. It is unclear how Gq-GPCR signaling in GFAP+ glia affects the activity of sympathetic neurons or contributes to SNS-regulated cardiovascular functions. In this study, we investigated whether Gq-GPCR activation in GFAP+ glia modulates the regulatory effect of the SNS on the heart; transgenic mice expressing Gq-coupled DREADD (designer receptors exclusively activated by designer drugs) (hM3Dq) selectively in GFAP+ glia were used to address this question in vivo. We found that acute Gq-GPCR activation in peripheral GFAP+ glia significantly accelerated heart rate and increased left ventricle contraction. Pharmacological experiments suggest that the glial-induced cardiac changes were due to Gq-GPCR activation in satellite glial cells within the sympathetic ganglion; this activation led to increased norepinephrine (NE) release and beta-1 adrenergic receptor activation within the heart. Chronic glial Gq-GPCR activation led to hypotension in female Gfap-hM3Dq mice. This study provides direct evidence that Gq-GPCR activation in peripheral GFAP+ glia regulates cardiovascular functions in vivo.
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Silva TM, Takakura AC, Moreira TS. Acute hypoxia activates hypothalamic paraventricular nucleus-projecting catecholaminergic neurons in the C1 region. Exp Neurol 2016; 285:1-11. [DOI: 10.1016/j.expneurol.2016.08.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/17/2016] [Accepted: 08/24/2016] [Indexed: 01/09/2023]
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Accorsi-Mendonça D, da Silva MP, Souza GMPR, Lima-Silveira L, Karlen-Amarante M, Amorim MR, Almado CEL, Moraes DJA, Machado BH. Pacemaking Property of RVLM Presympathetic Neurons. Front Physiol 2016; 7:424. [PMID: 27713705 PMCID: PMC5031694 DOI: 10.3389/fphys.2016.00424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 09/07/2016] [Indexed: 12/18/2022] Open
Abstract
Despite several studies describing the electrophysiological properties of RVLM presympathetic neurons, there is no consensus in the literature about their pacemaking property, mainly due to different experimental approaches used for recordings of neuronal intrinsic properties. In this review we are presenting a historical retrospective about the pioneering studies and their controversies on the intrinsic electrophysiological property of auto-depolarization of these cells in conjunction with recent studies from our laboratory documenting that RVLM presympathetic neurons present pacemaking capacity. We also discuss whether increased sympathetic activity observed in animal models of neurogenic hypertension (CIH and SHR) are dependent on changes in the intrinsic electrophysiological properties of these cells or due to changes in modulatory inputs from neurons of the respiratory network. We also highlight the key role of INaP as the major current contributing to the pacemaking property of RVLM presympathetic neurons.
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Affiliation(s)
- Daniela Accorsi-Mendonça
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Melina P da Silva
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - George M P R Souza
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Ludmila Lima-Silveira
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Marlusa Karlen-Amarante
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Mateus R Amorim
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Carlos E L Almado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil
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The integrative role of orexin/hypocretin neurons in nociceptive perception and analgesic regulation. Sci Rep 2016; 6:29480. [PMID: 27385517 PMCID: PMC4935841 DOI: 10.1038/srep29480] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/20/2016] [Indexed: 12/23/2022] Open
Abstract
The level of wakefulness is one of the major factors affecting nociception and pain. Stress-induced analgesia supports an animal’s survival via prompt defensive responses against predators or competitors. Previous studies have shown the pharmacological effects of orexin peptides on analgesia. However, orexin neurons contain not only orexin but also other co-transmitters such as dynorphin, neurotensin and glutamate. Thus, the physiological importance of orexin neuronal activity in nociception is unknown. Here we show that adult-stage selective ablation of orexin neurons enhances pain-related behaviors, while pharmacogenetic activation of orexin neurons induces analgesia. Additionally, we found correlative activation of orexin neurons during nociception using fiber photometry recordings of orexin neurons in conscious animals. These findings suggest an integrative role for orexin neurons in nociceptive perception and pain regulation.
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Huckstepp RT, Henderson LE, Cardoza KP, Feldman JL. Interactions between respiratory oscillators in adult rats. eLife 2016; 5. [PMID: 27300271 PMCID: PMC4907693 DOI: 10.7554/elife.14203] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/27/2016] [Indexed: 01/20/2023] Open
Abstract
Breathing in mammals is hypothesized to result from the interaction of two distinct oscillators: the preBötzinger Complex (preBötC) driving inspiration and the lateral parafacial region (pFL) driving active expiration. To understand the interactions between these oscillators, we independently altered their excitability in spontaneously breathing vagotomized urethane-anesthetized adult rats. Hyperpolarizing preBötC neurons decreased inspiratory activity and initiated active expiration, ultimately progressing to apnea, i.e., cessation of both inspiration and active expiration. Depolarizing pFL neurons produced active expiration at rest, but not when inspiratory activity was suppressed by hyperpolarizing preBötC neurons. We conclude that in anesthetized adult rats active expiration is driven by the pFL but requires an additional form of network excitation, i.e., ongoing rhythmic preBötC activity sufficient to drive inspiratory motor output or increased chemosensory drive. The organization of this coupled oscillator system, which is essential for life, may have implications for other neural networks that contain multiple rhythm/pattern generators. DOI:http://dx.doi.org/10.7554/eLife.14203.001 Mammals breathe air into and out of their lungs to absorb oxygen into the body and to remove carbon dioxide. The rhythm of breathing is most likely controlled by two groups of neurons in a part of the brain called the brain stem. One group called the preBötzinger Complex drives breathing in (inspiration), and normally, breathing out (expiration) occurs when the muscles responsible for inspiration relax. The other group of neurons – known as the lateral parafacial region – controls extra muscles that allow us to increase our breathing when we need to, such as during exercise. Huckstepp et al. set out to determine how these two groups of neurons interact with one another in anesthetized rats to produce a reliable and efficient pattern of breathing. The experiments provide further evidence that inspiration is mainly driven by the preBötzinger Complex. Whilst activity from the lateral parafacial region is needed to cause the rats to breathe out more forcefully than normal, a second low level of activity from another source is also required. This source could either be the preBötzinger Complex, or some unknown neurons that change their activity in response to the levels of oxygen and carbon dioxide in the blood or fluid of the brain. Further investigation is required to identify how these interactions go awry in diseases that affect breathing, such as sleep apneas. DOI:http://dx.doi.org/10.7554/eLife.14203.002
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Affiliation(s)
- Robert Tr Huckstepp
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Lauren E Henderson
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Kathryn P Cardoza
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Jack L Feldman
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
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Barna BF, Takakura AC, Mulkey DK, Moreira TS. Purinergic receptor blockade in the retrotrapezoid nucleus attenuates the respiratory chemoreflexes in awake rats. Acta Physiol (Oxf) 2016; 217:80-93. [PMID: 26647910 DOI: 10.1111/apha.12637] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/06/2015] [Accepted: 11/26/2015] [Indexed: 01/21/2023]
Abstract
AIM Recent evidence suggests that adenosine triphosfate (ATP)-mediated purinergic signalling at the level of the rostral ventrolateral medulla contributes to both central and peripheral chemoreceptor control of breathing and blood pressure: neurones in the retrotrapezoid nucleus (RTN) function as central chemoreceptors in part by responding to CO2 -evoked ATP release by activation of yet unknown P2 receptors, and nearby catecholaminergic C1 neurones regulate blood pressure responses to peripheral chemoreceptor activation by a P2Y1 receptor-dependent mechanism. However, potential contributions of purinergic signalling in the RTN to cardiorespiratory function in conscious animals have not been tested. METHODS Cardiorespiratory activity of unrestrained awake rats was measured in response to RTN injections of ATP, and during exposure to hypercapnia (7% CO2 ) or hypoxia (8% O2 ) under control conditions and after bilateral RTN injections of P2 receptor blockers (PPADS or MRS2179). RESULTS Unilateral injection of ATP into the RTN increased cardiorespiratory output by a P2-receptor-dependent mechanism. We also show that bilateral RTN injections of a non-specific P2 receptor blocker (pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS) reduced the ventilatory response to hypercapnia (7% CO2 ) and hypoxia (8% O2 ) in unanesthetized rats. Conversely, bilateral injections of a specific P2Y1 receptor blocker (MRS2179) into the RTN had no measurable effect on ventilatory responses elicited by hypercapnia or hypoxia. CONCLUSION These data exclude P2Y1 receptor involvement in the chemosensory control of breathing at the level of the RTN and show that ATP-mediated purinergic signalling contributes to central and peripheral chemoreflex control of breathing and blood pressure in awake rats.
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Affiliation(s)
- B. F. Barna
- Department of Physiology and Biophysics; Institute of Biomedical Science; University of São Paulo; São Paulo SP Brazil
| | - A. C. Takakura
- Department of Pharmacology; Institute of Biomedical Science; University of São Paulo; São Paulo SP Brazil
| | - D. K. Mulkey
- Department of Physiology and Neurobiology; University of Connecticut; Storrs CT USA
| | - T. S. Moreira
- Department of Physiology and Biophysics; Institute of Biomedical Science; University of São Paulo; São Paulo SP Brazil
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Silva JN, Lucena EV, Silva TM, Damasceno RS, Takakura AC, Moreira TS. Inhibition of the pontine Kölliker-Fuse nucleus reduces genioglossal activity elicited by stimulation of the retrotrapezoid chemoreceptor neurons. Neuroscience 2016; 328:9-21. [PMID: 27126558 DOI: 10.1016/j.neuroscience.2016.04.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 04/16/2016] [Accepted: 04/18/2016] [Indexed: 01/06/2023]
Abstract
The Kölliker-Fuse (KF) region, located in the dorsolateral pons, projects to several brainstem areas involved in respiratory regulation, including the chemoreceptor neurons within the retrotrapezoid nucleus (RTN). Several lines of evidence indicate that the pontine KF region plays an important role in the control of the upper airways for the maintenance of appropriate airflow to and from the lungs. Specifically, we hypothesized that the KF region is involved in mediating the response of the hypoglossal motor activity to central respiratory chemoreflex activation and to stimulation of the chemoreceptor neurons within the RTN region. To test this hypothesis, we combined immunohistochemistry and physiological experiments. We found that in the KF, the majority of biotinylated dextran amine (BDA)-labeled axonal varicosities contained detectable levels of vesicular glutamate transporter-2 (VGLUT2), but few contained glutamic acid decarboxylase-67 (GAD67). The majority of the RTN neurons that were FluorGold (FG)-immunoreactive (i.e., projected to the KF) contained hypercapnia-induced Fos, but did not express tyrosine hydroxylase. In urethane-anesthetized sino-aortic denervated and vagotomized male Wistar rats, hypercapnia (10% CO2) or N-methyl-d-aspartate (NMDA) injection (0.1mM) in the RTN increased diaphragm (DiaEMG) and genioglossus muscle (GGEMG) activities and elicited abdominal (AbdEMG) activity. Bilateral injection of muscimol (GABA-A agonist; 2mM) into the KF region reduced the increase in DiaEMG and GGEMG produced by hypercapnia or NMDA into the RTN. Our data suggest that activation of chemoreceptor neurons in the RTN produces a significant increase in the genioglossus muscle activity and the excitatory pathway is dependent on the neurons located in the dorsolateral pontine KF region.
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Affiliation(s)
- Josiane N Silva
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil
| | - Elvis V Lucena
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil
| | - Talita M Silva
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil
| | - Rosélia S Damasceno
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo/SP, Brazil.
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Deuchars SA, Lall VK. Sympathetic preganglionic neurons: properties and inputs. Compr Physiol 2016; 5:829-69. [PMID: 25880515 DOI: 10.1002/cphy.c140020] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The sympathetic nervous system comprises one half of the autonomic nervous system and participates in maintaining homeostasis and enabling organisms to respond in an appropriate manner to perturbations in their environment, either internal or external. The sympathetic preganglionic neurons (SPNs) lie within the spinal cord and their axons traverse the ventral horn to exit in ventral roots where they form synapses onto postganglionic neurons. Thus, these neurons are the last point at which the central nervous system can exert an effect to enable changes in sympathetic outflow. This review considers the degree of complexity of sympathetic control occurring at the level of the spinal cord. The morphology and targets of SPNs illustrate the diversity within this group, as do their diverse intrinsic properties which reveal some functional significance of these properties. SPNs show high degrees of coupled activity, mediated through gap junctions, that enables rapid and coordinated responses; these gap junctions contribute to the rhythmic activity so critical to sympathetic outflow. The main inputs onto SPNs are considered; these comprise afferent, descending, and interneuronal influences that themselves enable functionally appropriate changes in SPN activity. The complexity of inputs is further demonstrated by the plethora of receptors that mediate the different responses in SPNs; their origins and effects are plentiful and diverse. Together these different inputs and the intrinsic and coupled activity of SPNs result in the rhythmic nature of sympathetic outflow from the spinal cord, which has a variety of frequencies that can be altered in different conditions.
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Affiliation(s)
- Susan A Deuchars
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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Afferent and efferent connections of C1 cells with spinal cord or hypothalamic projections in mice. Brain Struct Funct 2015; 221:4027-4044. [PMID: 26560463 DOI: 10.1007/s00429-015-1143-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/02/2015] [Indexed: 12/20/2022]
Abstract
The axonal projections and synaptic input of the C1 adrenergic neurons of the rostral ventrolateral medulla (VLM) were examined using transgenic dopamine-beta hydroxylase Cre mice and modified rabies virus. Cre-dependent viral vectors expressing TVA (receptor for envelopeA) and rabies glycoprotein were injected into the left VLM. EnvelopeA-pseudotyped rabies-EGFP glycoprotein-deficient virus (rabies-EGFP) was injected 4-6 weeks later in either thoracic spinal cord (SC) or hypothalamus. TVA immunoreactivity was detected almost exclusively (95 %) in VLM C1 neurons. In mice with SC injections of rabies-EGFP, starter cells (expressing TVA + EGFP) were found at the rostral end of the VLM; in mice with hypothalamic injections starter C1 cells were located more caudally. C1 neurons innervating SC or hypothalamus had other terminal fields in common (e.g., dorsal vagal complex, locus coeruleus, raphe pallidus and periaqueductal gray matter). Putative inputs to C1 cells with SC or hypothalamic projections originated from the same brain regions, especially the lower brainstem reticular core from spinomedullary border to rostral pons. Putative input neurons to C1 cells were also observed in the nucleus of the solitary tract, caudal VLM, caudal spinal trigeminal nucleus, cerebellum, periaqueductal gray matter and inferior and superior colliculi. In sum, regardless of whether they innervate SC or hypothalamus, VLM C1 neurons receive input from the same general brain regions. One interpretation is that many types of somatic or internal stimuli recruit these neurons en bloc to produce a stereotyped acute stress response with sympathetic, parasympathetic, vigilance and neuroendocrine components.
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Kourtesis I, Kasparov S, Verkade P, Teschemacher AG. Ultrastructural Correlates of Enhanced Norepinephrine and Neuropeptide Y Cotransmission in the Spontaneously Hypertensive Rat Brain. ASN Neuro 2015; 7:7/5/1759091415610115. [PMID: 26514659 PMCID: PMC4641560 DOI: 10.1177/1759091415610115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The spontaneously hypertensive rat (SHR) replicates many clinically relevant features of human essential hypertension and also exhibits behavioral symptoms of attention-deficit/hyperactivity disorder and dementia. The SHR phenotype is highly complex and cannot be explained by a single genetic or physiological mechanism. Nevertheless, numerous studies including our own work have revealed striking differences in central catecholaminergic transmission in SHR such as increased vesicular catecholamine content in the ventral brainstem. Here, we used immunolabeling followed by confocal microscopy and electron microscopy to quantify vesicle sizes and populations across three catecholaminergic brain areas—nucleus tractus solitarius and rostral ventrolateral medulla, both key regions for cardiovascular control, and the locus coeruleus. We also studied colocalization of neuropeptide Y (NPY) in norepinephrine and epinephrine-containing neurons as NPY is a common cotransmitter with central and peripheral catecholamines. We found significantly increased expression and coexpression of NPY in norepinephrine and epinephrine-positive neurons of locus coeruleus in SHR compared with Wistar rats. Ultrastructural analysis revealed immunolabeled vesicles of 150 to 650 nm in diameter (means ranging from 250 to 300 nm), which is much larger than previously reported. In locus coeruleus and rostral ventrolateral medulla, but not in nucleus tractus solitarius, of SHR, noradrenergic and adrenergic vesicles were significantly larger and showed increased NPY colocalization when compared with Wistar rats. Our morphological evidence underpins the hypothesis of hyperactivity of the noradrenergic and adrenergic system and increased norepinephrine and epinephrine and NPY cotransmission in specific brain areas in SHR. It further strengthens the argument for a prohypertensive role of C1 neurons in the rostral ventrolateral medulla as a potential causative factor for essential hypertension.
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Affiliation(s)
- Ioannis Kourtesis
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK Sars International Centre for Marine Molecular Biology, University of Bergen, Norway
| | - Sergey Kasparov
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK
| | - Paul Verkade
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK School of Biochemistry, University of Bristol, UK Wolfson Bioimaging Facility, University of Bristol, UK
| | - Anja G Teschemacher
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK
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Trapp S, Cork SC. PPG neurons of the lower brain stem and their role in brain GLP-1 receptor activation. Am J Physiol Regul Integr Comp Physiol 2015; 309:R795-804. [PMID: 26290108 DOI: 10.1152/ajpregu.00333.2015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 08/13/2015] [Indexed: 01/28/2023]
Abstract
Within the brain, glucagon-like peptide-1 (GLP-1) affects central autonomic neurons, including those controlling the cardiovascular system, thermogenesis, and energy balance. Additionally, GLP-1 influences the mesolimbic reward system to modulate the rewarding properties of palatable food. GLP-1 is produced in the gut and by hindbrain preproglucagon (PPG) neurons, located mainly in the nucleus tractus solitarii (NTS) and medullary intermediate reticular nucleus. Transgenic mice expressing glucagon promoter-driven yellow fluorescent protein revealed that PPG neurons not only project to central autonomic control regions and mesolimbic reward centers, but also strongly innervate spinal autonomic neurons. Therefore, these brain stem PPG neurons could directly modulate sympathetic outflow through their spinal inputs to sympathetic preganglionic neurons. Electrical recordings from PPG neurons in vitro have revealed that they receive synaptic inputs from vagal afferents entering via the solitary tract. Vagal afferents convey satiation to the brain from signals like postprandial gastric distention or activation of peripheral GLP-1 receptors. CCK and leptin, short- and long-term satiety peptides, respectively, increased the electrical activity of PPG neurons, while ghrelin, an orexigenic peptide, had no effect. These findings indicate that satiation is a main driver of PPG neuronal activation. They also show that PPG neurons are in a prime position to respond to both immediate and long-term indicators of energy and feeding status, enabling regulation of both energy balance and general autonomic homeostasis. This review discusses the question of whether PPG neurons, rather than gut-derived GLP-1, are providing the physiological substrate for the effects elicited by central nervous system GLP-1 receptor activation.
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Affiliation(s)
- Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Simon C Cork
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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Bourassa EA, Stedenfeld KA, Sved AF, Speth RC. Selective C1 Lesioning Slightly Decreases Angiotensin II Type I Receptor Expression in the Rat Rostral Ventrolateral Medulla (RVLM). Neurochem Res 2015; 40:2113-20. [PMID: 26138553 DOI: 10.1007/s11064-015-1649-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 06/16/2015] [Accepted: 06/20/2015] [Indexed: 01/28/2023]
Abstract
Cardiovascular homeostasis is regulated in large part by the rostral ventrolateral medulla (RVLM) in mammals. Projections from the RVLM to the intermediolateral column of the thoracolumbar spinal cord innervate preganglionic neurons of the sympathetic nervous system causing elevation of blood pressure and heart rate. A large proportion, but not all, of the neurons in the RVLM contain the enzymes necessary for the production of epinephrine and are identified as the C1 cell group. Angiotensin II (Ang II) activates the RVLM acting upon AT1 receptors. To assess the proportion of AT1 receptors that are located on C1 neurons in the rat RVLM this study employed an antibody to dopamine-beta-hydroxylase conjugated to saporin, to selectively destroy C1 neurons in the RVLM. Expression of tyrosine hydroxylase immunoreactive neurons in the RVLM was reduced by 57 % in the toxin injected RVLM compared to the contralateral RVLM. In contrast, densitometric analysis of autoradiographic images of (125)I-sarcosine(1), isoleucine(8) Ang II binding to AT1 receptors of the injected side RVLM revealed a small (10 %) reduction in AT1-receptor expression compared to the contralateral RVLM. These results suggest that the majority of AT1 receptors in the rat RVLM are located on non-C1 neurons or glia.
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Affiliation(s)
- Erick A Bourassa
- Mississippi College, 200 S Capitol St, Clinton, MS, 39058, USA.
- Department of Pharmacology, School of Pharmacy, University of Mississippi, Oxford, MS, 38677, USA.
| | - Kristen A Stedenfeld
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Alan F Sved
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
| | - Robert C Speth
- Department of Pharmacology, School of Pharmacy, University of Mississippi, Oxford, MS, 38677, USA.
- College of Pharmacy, Nova Southeastern University, 3200 S. University Dr., Fort Lauderdale, FL, 33328, USA.
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Abstract
In conscious mammals, hypoxia or hypercapnia stimulates breathing while theoretically exerting opposite effects on central respiratory chemoreceptors (CRCs). We tested this theory by examining how hypoxia and hypercapnia change the activity of the retrotrapezoid nucleus (RTN), a putative CRC and chemoreflex integrator. Archaerhodopsin-(Arch)-transduced RTN neurons were reversibly silenced by light in anesthetized rats. We bilaterally transduced RTN and nearby C1 neurons with Arch (PRSx8-ArchT-EYFP-LVV) and measured the cardiorespiratory consequences of Arch activation (10 s) in conscious rats during normoxia, hypoxia, or hyperoxia. RTN photoinhibition reduced breathing equally during non-REM sleep and quiet wake. Compared with normoxia, the breathing frequency reduction (Δf(R)) was larger in hyperoxia (65% FiO2), smaller in 15% FiO2, and absent in 12% FiO2. Tidal volume changes (ΔV(T)) followed the same trend. The effect of hypoxia on Δf(R) was not arousal-dependent but was reversed by reacidifying the blood (acetazolamide; 3% FiCO2). Δf(R) was highly correlated with arterial pH up to arterial pH (pHa) 7.5 with no frequency inhibition occurring above pHa 7.53. Blood pressure was minimally reduced suggesting that C1 neurons were very modestly inhibited. In conclusion, RTN neurons regulate eupneic breathing about equally during both sleep and wake. RTN neurons are the first putative CRCs demonstrably silenced by hypocapnic hypoxia in conscious mammals. RTN neurons are silent above pHa 7.5 and increasingly active below this value. During hyperoxia, RTN activation maintains breathing despite the inactivity of the carotid bodies. Finally, during hypocapnic hypoxia, carotid body stimulation increases breathing frequency via pathways that bypass RTN.
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Abstract
Contiguous brain regions associated with a given behavior are increasingly being divided into subregions associated with distinct aspects of that behavior. Using recently developed neuronal hyperpolarizing technologies, we functionally dissect the parafacial region in the medulla, which contains key elements of the central pattern generator for breathing that are important in central CO2-chemoreception and for gating active expiration. By transfecting different populations of neighboring neurons with allatostatin or HM4D Gi/o-coupled receptors, we analyzed the effect of their hyperpolarization on respiration in spontaneously breathing vagotomized urethane-anesthetized rats. We identify two functionally separate parafacial nuclei: ventral (pFV) and lateral (pFL). Disinhibition of the pFL with bicuculline and strychnine led to active expiration. Hyperpolarizing pFL neurons had no effect on breathing at rest, or changes in inspiratory activity induced by hypoxia and hypercapnia; however, hyperpolarizing pFL neurons attenuated active expiration when it was induced by hypercapnia, hypoxia, or disinhibition of the pFL. In contrast, hyperpolarizing pFV neurons affected breathing at rest by decreasing inspiratory-related activity, attenuating the hypoxia- and hypercapnia-induced increase in inspiratory activity, and when present, reducing expiratory-related abdominal activity. Together with previous observations, we conclude that the pFV provides a generic excitatory drive to breathe, even at rest, whereas the pFL is a conditional oscillator quiet at rest that, when activated, e.g., during exercise, drives active expiration.
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Abstract
Brainstem catecholaminergic neurons play key roles in the autonomic, neuroendocrine, and behavioral responses to glucoprivation, yet the functions of the individual groups are not fully understood. Adrenergic C3 neurons project widely throughout the brain, including densely to sympathetic preganglionic neurons in the spinal cord, yet their function is completely unknown. Here we demonstrate in rats that optogenetic stimulation of C3 neurons induces sympathoexcitatory, cardiovasomotor functions. These neurons are activated by glucoprivation, but unlike the C1 cell group, not by hypotension. The cardiovascular activation induced by C3 neurons is less than that induced by optogenetic stimulation of C1 neurons; however, combined stimulation produces additive sympathoexcitatory and cardiovascular effects. The varicose axons of C3 neurons largely overlap with those of C1 neurons in the region of sympathetic preganglionic neurons in the spinal cord; however, regional differences point to effects on different sympathetic outflows. These studies definitively demonstrate the first known function of C3 neurons as unique cardiovasomotor stimulatory cells, embedded in the brainstem networks regulating cardiorespiratory activity and the response to glucoprivation.
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Dempsey B, Turner AJ, Le S, Sun QJ, Bou Farah L, Allen AM, Goodchild AK, McMullan S. Recording, labeling, and transfection of single neurons in deep brain structures. Physiol Rep 2015; 3:3/1/e12246. [PMID: 25602013 PMCID: PMC4387759 DOI: 10.14814/phy2.12246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Genetic tools that permit functional or connectomic analysis of neuronal circuits are rapidly transforming neuroscience. The key to deployment of such tools is selective transfection of target neurons, but to date this has largely been achieved using transgenic animals or viral vectors that transduce subpopulations of cells chosen according to anatomical rather than functional criteria. Here, we combine single‐cell transfection with conventional electrophysiological recording techniques, resulting in three novel protocols that can be used for reliable delivery of conventional dyes or genetic material in vitro and in vivo. We report that techniques based on single cell electroporation yield reproducible transfection in vitro, and offer a simple, rapid and reliable alternative to established dye‐labeling techniques in vivo, but are incompatible with targeted transfection in deep brain structures. In contrast, we show that intracellular electrophoresis of plasmid DNA transfects brainstem neurons recorded up to 9 mm deep in the anesthetized rat. The protocols presented here require minimal, if any, modification to recording hardware, take seconds to deploy, and yield high recovery rates in vitro (dye labeling: 89%, plasmid transfection: 49%) and in vivo (dye labeling: 66%, plasmid transfection: 27%). They offer improved simplicity compared to the juxtacellular labeling technique and for the first time offer genetic manipulation of functionally characterized neurons in previously inaccessible brain regions. The ability to label individual neurons after electrophysiological characterization of their functional properties is a foundational technique in neuroscience. A number of approaches that achieve this goal have been described, but all are technically challenging. Here, we describe a simple approach that is rapid, reliable, and compatible with delivery of conventional dyes or large plasmid DNA molecules.
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Affiliation(s)
- Bowen Dempsey
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Anita J Turner
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Sheng Le
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Qi-Jian Sun
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Lama Bou Farah
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Ann K Goodchild
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
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49
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Jancovski N, Carter DA, Connelly AA, Stevens E, Bassi JK, Menuet C, Allen AM. Angiotensin type 1A receptor expression in C1 neurons of the rostral ventrolateral medulla contributes to the development of angiotensin-dependent hypertension. Exp Physiol 2014; 99:1597-610. [DOI: 10.1113/expphysiol.2014.082073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nikola Jancovski
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - David A. Carter
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - Angela A. Connelly
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - Elyse Stevens
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - Jaspreet K. Bassi
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - Clement Menuet
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
| | - Andrew M. Allen
- Department of Physiology; University of Melbourne; Melbourne Victoria 3010 Australia
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Melbourne Victoria 3010 Australia
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50
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Briant LJB, Stalbovskiy AO, Nolan MF, Champneys AR, Pickering AE. Increased intrinsic excitability of muscle vasoconstrictor preganglionic neurons may contribute to the elevated sympathetic activity in hypertensive rats. J Neurophysiol 2014; 112:2756-78. [PMID: 25122704 PMCID: PMC4254885 DOI: 10.1152/jn.00350.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hypertension is associated with pathologically increased sympathetic drive to the vasculature. This has been attributed to increased excitatory drive to sympathetic preganglionic neurons (SPN) from brainstem cardiovascular control centers. However, there is also evidence supporting increased intrinsic excitability of SPN. To test this hypothesis, we made whole cell recordings of muscle vasoconstrictor-like (MVClike) SPN in the working-heart brainstem preparation of spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats. The MVClike SPN have a higher spontaneous firing frequency in the SH rat (3.85 ± 0.4 vs. 2.44 ± 0.4 Hz in WKY; P = 0.011) with greater respiratory modulation of their activity. The action potentials of SH SPN had smaller, shorter afterhyperpolarizations (AHPs) and showed diminished transient rectification indicating suppression of an A-type potassium conductance (IA). We developed mathematical models of the SPN to establish if changes in their intrinsic properties in SH rats could account for their altered firing. Reduction of the maximal conductance density of IA by 15–30% changed the excitability and output of the model from the WKY to a SH profile, with increased firing frequency, amplified respiratory modulation, and smaller AHPs. This change in output is predominantly a consequence of altered synaptic integration. Consistent with these in silico predictions, we found that intrathecal 4-aminopyridine (4-AP) increased sympathetic nerve activity, elevated perfusion pressure, and augmented Traube-Hering waves. Our findings indicate that IA acts as a powerful filter on incoming synaptic drive to SPN and that its diminution in the SH rat is potentially sufficient to account for the increased sympathetic output underlying hypertension.
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Affiliation(s)
- Linford J B Briant
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom; and
| | - Alexey O Stalbovskiy
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Matthew F Nolan
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Alan R Champneys
- Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom; and
| | - Anthony E Pickering
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom; Department of Anaesthesia, University Hospitals Bristol, Bristol, United Kingdom;
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