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Iyer SH, Hinman JE, Warren T, Matthews SA, Simeone TA, Simeone KA. Altered ventilatory responses to hypercapnia-hypoxia challenges in a preclinical SUDEP model involve orexin neurons. Neurobiol Dis 2024; 199:106592. [PMID: 38971479 DOI: 10.1016/j.nbd.2024.106592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 06/25/2024] [Accepted: 07/02/2024] [Indexed: 07/08/2024] Open
Abstract
Failure to recover from repeated hypercapnia and hypoxemia (HH) challenges caused by severe GCS and postictal apneas may contribute to sudden unexpected death in epilepsy (SUDEP). Our previous studies found orexinergic dysfunction contributes to respiratory abnormalities in a preclinical model of SUDEP, Kcna1-/- mice. Here, we developed two gas challenges consisting of repeated HH exposures and used whole body plethysmography to determine whether Kcna1-/- mice have detrimental ventilatory responses. Kcna1-/- mice exhibited an elevated ventilatory response to a mild repeated hypercapnia-hypoxia (HH) challenge compared to WT. Moreover, 71% of Kcna1-/- mice failed to survive a severe repeated HH challenge, whereas all WT mice recovered. We next determined whether orexin was involved in these differences. Pretreating Kcna1-/- mice with a dual orexin receptor antagonist rescued the ventilatory response during the mild challenge and all subjects survived the severe challenge. In ex vivo extracellular recordings in the lateral hypothalamus of coronal brain slices, we found reducing pH either inhibits or stimulates putative orexin neurons similar to other chemosensitive neurons; however, a significantly greater percentage of putative orexin neurons from Kcna1-/-mice were stimulated and the magnitude of stimulation was increased resulting in augmentation of the calculated chemosensitivity index relative to WT. Collectively, our data suggest that increased chemosensitive activity of orexin neurons may be pathologic in the Kcna1-/- mouse model of SUDEP, and contribute to elevated ventilatory responses. Our preclinical data suggest that those at high risk for SUDEP may be more sensitive to HH challenges, whether induced by seizures or other means; and the depth and length of the HH exposure could dictate the probability of survival.
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Affiliation(s)
- Shruthi H Iyer
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Jillian E Hinman
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Ted Warren
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Stephanie A Matthews
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Timothy A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Kristina A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE 68178, USA.
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Zhu Y, Deng T, Ma L, Sun L, Hao Y, Yu H, Yuan F, Tian Y, Wang S. Acid-sensing ion channel 1 in nucleus tractus solitarii neurons contributes to the enhanced CO 2-stimulated cardiorespiratory effect in spontaneously hypertensive rats. Life Sci 2024; 351:122853. [PMID: 38889841 DOI: 10.1016/j.lfs.2024.122853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 06/12/2024] [Accepted: 06/14/2024] [Indexed: 06/20/2024]
Abstract
AIMS Activation of central respiratory chemoreceptors provides excitatory drive to both respiratory and sympathetic outputs. The enhanced respiratory-sympathetic coupling contributes to the onset and development of hypertension. However, the specific central targets and molecular mechanisms involved in this process remain elusive. This study aimed to investigate the role of acid-sensing ion channel 1 (ASIC1) in nucleus tractus solitarii (NTS) neurons in CO2-stimulated cardiorespiratory effects in spontaneously hypertensive rats (SHRs). MAIN METHODS Respiration and blood pressure of conscious rats were recorded by whole-body plethysmography and telemetry, respectively. Western blot was used to detect the expression difference of ASIC1 protein in NTS region between Wistar-Kyoto (WKY) rats and SHRs. Excitability of NTS neurons were assessed by extracellular recordings. KEY FINDINGS Compared to WKY rats, the enhanced CO2-stimulated cardiopulmonary effect and up-regulation of ASIC1 in the NTS were already observed in 4-week-old prehypertensive SHRs. Furthermore, specific blockade of ASIC1 effectively attenuated the CO2-stimulated increase in firing rate of NTS neurons in anesthetized adult SHRs. Intracerebroventricular injections of the ASIC1a blocker PcTx1 or knockdown Asic1 in NTS neurons significantly reduced the heightened CO2-stimulated ventilatory response, and diminished the CO2-stimulated increase in arterial pressure and heart rate in adult SHRs. SIGNIFICANCE These findings showed that dysregulated ASIC1 signaling in the NTS contribute to the exaggerated CO2-stimulated cardiorespiratory effects observed in SHRs.
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Affiliation(s)
- Yufang Zhu
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Tianjiao Deng
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Lan Ma
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Lu Sun
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Yinchao Hao
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Hongxiao Yu
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Fang Yuan
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China; Hebei Province Key Laboratory of Neurophysiology, Shijiazhuang 050017, China
| | - Yanming Tian
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China; Hebei Province Key Laboratory of Neurophysiology, Shijiazhuang 050017, China.
| | - Sheng Wang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China; Hebei Province Key Laboratory of Neurophysiology, Shijiazhuang 050017, China.
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Zahner MR, Brown MC, Chandley MJ. Inactivation of the paraventricular nucleus attenuates the cardiogenic sympathetic afferent reflex in the spontaneously hypertensive rat. J Hypertens 2024; 42:70-78. [PMID: 37889604 PMCID: PMC10792548 DOI: 10.1097/hjh.0000000000003542] [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] [Indexed: 10/29/2023]
Abstract
BACKGROUND Myocardial ischemia causes the release of bradykinin, which stimulates cardiac afferents, causing sympathetic excitation and chest pain. Glutamatergic activation of the paraventricular hypothalamic nucleus (PVN) in the spontaneously hypertensive rat (SHR) drives elevated basal sympathetic activity. Thus, we tested the hypothesis that inactivation of the PVN attenuates the elevated reflex response to epicardial bradykinin in the SHR and that ionotropic PVN glutamate receptors mediate the elevated reflex. METHODS We recorded the arterial pressure and renal sympathetic nerve activity (RSNA) response to epicardial bradykinin application in anesthetized SHR and Wistar Kyoto (WKY) rats before and after PVN microinjection of GABA A agonist muscimol or ionotropic glutamate receptor antagonist kynurenic acid. RESULTS Muscimol significantly decreased the arterial pressure response to bradykinin from 180.4 ± 5.8 to 119.5 ± 6.9 mmHg in the SHR and from 111.8 ± 7.0 to 84.2 ± 8.3 mmHg in the WKY and the RSNA response from 186.2 ± 7.1 to 142.7 ± 7.3% of baseline in the SHR and from 201.0 ± 11.5 to 160.2 ± 9.3% of baseline in the WKY. Kynurenic acid significantly decreased the arterial pressure response in the SHR from 164.5 ± 5.0 to 126.2 ± 7.7 mmHg and the RSNA response from 189.9 ± 13.7to 168.5 ± 12.7% of baseline but had no effect in the WKY. CONCLUSION These results suggest that tonic PVN activity is critical for the full manifestation of the CSAR in both the WKY and SHR. Glutamatergic PVN activity contributes to the augmented CSAR observed in the SHR.
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Affiliation(s)
- Matthew R Zahner
- Department of Health Sciences, East Tennessee State University College of Public Health
| | - Mary C Brown
- Department of Health Sciences, East Tennessee State University College of Public Health
| | - Michelle J Chandley
- Department of Biomedical Science, East Tennessee State University College of Medicine, Johnson City, Tennessee, USA
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Giannoni A, Borrelli C, Gentile F, Sciarrone P, Spießhöfer J, Piepoli M, Richerson GB, Floras JS, Coats AJS, Javaheri S, Emdin M, Passino C. Autonomic and respiratory consequences of altered chemoreflex function: clinical and therapeutic implications in cardiovascular diseases. Eur J Heart Fail 2023; 25:642-656. [PMID: 36907827 PMCID: PMC10989193 DOI: 10.1002/ejhf.2819] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 02/10/2023] [Accepted: 02/26/2023] [Indexed: 03/14/2023] Open
Abstract
The importance of chemoreflex function for cardiovascular health is increasingly recognized in clinical practice. The physiological function of the chemoreflex is to constantly adjust ventilation and circulatory control to match respiratory gases to metabolism. This is achieved in a highly integrated fashion with the baroreflex and the ergoreflex. The functionality of chemoreceptors is altered in cardiovascular diseases, causing unstable ventilation and apnoeas and promoting sympathovagal imbalance, and it is associated with arrhythmias and fatal cardiorespiratory events. In the last few years, opportunities to desensitize hyperactive chemoreceptors have emerged as potential options for treatment of hypertension and heart failure. This review summarizes up to date evidence of chemoreflex physiology/pathophysiology, highlighting the clinical significance of chemoreflex dysfunction, and lists the latest proof of concept studies based on modulation of the chemoreflex as a novel target in cardiovascular diseases.
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Affiliation(s)
- Alberto Giannoni
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
| | | | - Francesco Gentile
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
| | | | - Jens Spießhöfer
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- University of Aachen, Aachen, Germany
| | | | | | - John S Floras
- Division of Cardiology, Mount Sinai Hospital, University of Toronto, Ontario, Canada
| | | | - Shahrokh Javaheri
- Division of Pulmonary and Sleep Medicine, Bethesda North Hospital, Cincinnati, Ohio, Division of Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati, Cincinnati, Ohio, and Division of Cardiology, The Ohio State University, Columbus, Ohio USA
| | - Michele Emdin
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
| | - Claudio Passino
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione Toscana G. Monasterio, Pisa, Italy
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Ben Musa R, Cornelius-Green J, Hasser EM, Cummings KJ. The effect of orexin on the hypoxic ventilatory response of female rats is greatest in the active phase during diestrus. J Appl Physiol (1985) 2023; 134:638-648. [PMID: 36656978 PMCID: PMC10010922 DOI: 10.1152/japplphysiol.00661.2022] [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: 11/02/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/21/2023] Open
Abstract
We recently showed that in male rats, orexin contributes to the hypoxic ventilatory response (HVR), with a stronger effect in the active phase. The effect of orexin on the HVR in females has not been investigated. As estrogen can inhibit orexin neurons, here we hypothesized that orexin neurons are activated by hypoxia and facilitate the HVR only in diestrus, when estrogen is low. We exposed female rats (n = 10) to near-isocapnic hypoxia ([Formula: see text] from 0.21 to 0.09) over ∼5 min, after vehicle and again after suvorexant (a dual OxR antagonist; 20 mg/kg ip), with ventilation measured using whole body plethysmography. Each rat was tested in proestrus or estrus (p/estrus), and again in diestrus, during both inactive and active phases. We also performed immunohistochemistry (IHC) to determine the proportion of orexin neurons activated by acute hypoxia during diestrus (n = 6) or proestrus/estrus (n = 6) in the active phase. In the inactive phase, the HVR was unaffected by OxR blockade, irrespective of estrus stage. In the active phase, the effect of OxR blockade depended on stage: the slope of the HVR was significantly reduced by OxR blockade only during diestrus. IHC revealed that hypoxia activated more orexin neurons during diestrus compared with p/estrus. We conclude that in females, orexin neurons are activated by hypoxia and contribute to the HVR only in diestrus when estrogen levels are low. Stage of the estrus cycle should be considered when examining the physiological function of orexin neurons in females.NEW & NOTEWORTHY We previously showed that orexin facilitates the hypoxic ventilatory response (HVR) of adult male rats during the active phase. Others have shown that estrogen inhibits orexin neurons. Here we show that orexin neurons are activated by hypoxia and facilitate the HVR of adult female rats during the active phase, but only in diestrus. These data suggest that orexin neurons facilitate the HVR in females when they are free from the inhibitory effects of estrogen.
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Affiliation(s)
- Ruwaida Ben Musa
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
| | - Jennifer Cornelius-Green
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
| | - Eileen M Hasser
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
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CO 2 exposure enhances Fos expression in hypothalamic neurons in rats during the light and dark phases of the diurnal cycle. Brain Struct Funct 2022; 227:2667-2679. [PMID: 36109371 DOI: 10.1007/s00429-022-02562-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 08/29/2022] [Indexed: 12/30/2022]
Abstract
Orexinergic (OX) neurons in the lateral hypothalamus (LH), perifornical area (PFA) and dorsomedial hypothalamus (DMH) play a role in the hypercapnic ventilatory response, presumably through direct inputs to central pattern generator sites and/or through interactions with other chemosensitive regions. OX neurons can produce and release orexins, excitatory neuropeptides involved in many functions, including physiological responses to changes in CO2/pH. Thus, in the present study, we tested the hypothesis that different nuclei (LH, PFA and DMH) where the orexinergic neurons are located, show distinct activation by CO2 during the light-dark cycle phases. For this purpose, we evaluated the Fos and OXA expression by immunohistochemistry to identify neurons that co-localize Fos + OXA in the LH, LPeF, MPeF and DMH in the light-inactive and dark-active phase in Wistar rats subjected to 3 h of normocapnia or hypercapnia (7% CO2). Quantitative analyses of immunoreactive neurons show that hypercapnia caused an increase in the number of neurons expressing Fos in the LH, LPeF, MPeF and DMH in the light and dark phases. In addition, the number of Fos + OXA neurons increased in the LPeF and DMH independently of the phases of the diurnal cycle; whereas in the MPeF, this increase was observed exclusively in the light phase. Thus, we suggest that OX neurons are selectively activated by hypercapnia throughout the diurnal cycle, reinforcing the differential role of nuclei in the hypothalamus during central chemosensitivity.
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Spinieli RL, Ben Musa R, Cornelius-Green J, Hasser EM, Cummings KJ. Orexin facilitates the ventilatory and behavioral responses of rats to hypoxia. Am J Physiol Regul Integr Comp Physiol 2022; 322:R581-R596. [PMID: 35380477 PMCID: PMC9109809 DOI: 10.1152/ajpregu.00334.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/22/2022] [Accepted: 03/30/2022] [Indexed: 02/03/2023]
Abstract
Orexin neurons are sensitive to CO2 and contribute to cardiorespiratory homeostasis as well as sensorimotor control. Whether orexin facilitates respiratory and behavioral responses to acute hypoxia is unclear. We hypothesized that orexin neurons are activated by acute hypoxia and that orexin facilitates the hypoxic ventilatory response (HVR), as well as the arterial blood pressure (ABP) and behavioral (movement) responses to acute hypoxia. We further hypothesized that orexin has greater effects in the active phase of the rat circadian cycle, when orexin neurons have high activity. Using whole body plethysmography with EEG, EMG, and the dual-orexin receptor (OxR) antagonist suvorexant (20 mg/kg ip), we determined the effect of OxR blockade on the respiratory, ABP, and behavioral responses of adult rats to acute, graded hypoxia ([Formula: see text]= 0.15, 0.13, 0.11, and 0.09) and hyperoxic hypercapnia ([Formula: see text]= 0.05; [Formula: see text]= 0.95). OxR blockade had no effect on eupnea. OxR blockade significantly reduced the HVR in both inactive and active phases, with a stronger effect in the active phase. OxR blockade reduced the behavioral response to acute hypoxia in the active phase. The central component of the ventilatory and the ABP responses to hypercapnia were reduced by OxR blockade solely in the inactive phase. In the inactive phase, hypoxia activated ∼10% of orexin neurons in the perifornical hypothalamus. These data suggest that orexin neurons participate in the peripheral chemoreflex to facilitate the ventilatory and behavioral responses to acute hypoxia in rats, particularly in the active phase. Orexin also facilitates central chemoreflex responses to CO2 in the inactive phase.
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Affiliation(s)
- Richard L Spinieli
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Ruwaida Ben Musa
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Jennifer Cornelius-Green
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Eileen M Hasser
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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Sayegh ALC, Fan JL, Vianna LC, Dawes M, Paton JFR, Fisher JP. Sex-differences in the sympathetic neurocirculatory responses to chemoreflex activation. J Physiol 2022; 600:2669-2689. [PMID: 35482235 PMCID: PMC9324851 DOI: 10.1113/jp282327] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 04/25/2022] [Indexed: 11/08/2022] Open
Abstract
Abstract The purpose of this study was to determine whether there are sex differences in the cardiorespiratory and sympathetic neurocirculatory responses to central, peripheral, and combined central and peripheral chemoreflex activation. Ten women (29 ± 6 years, 22.8 ± 2.4 kg/m2: mean ± SD) and 10 men (30 ± 7 years, 24.8 ± 3.2 kg/m2) undertook randomized 5 min breathing trials of: room air (eucapnia), isocapnic hypoxia (10% oxygen (O2); peripheral chemoreflex activation), hypercapnic hyperoxia (7% carbon dioxide (CO2), 50% O2; central chemoreflex activation) and hypercapnic hypoxia (7% CO2, 10% O2; central and peripheral chemoreflex activation). Control trials of isocapnic hyperoxia (peripheral chemoreflex inhibition) and hypocapnic hyperoxia (central and peripheral chemoreflex inhibition) were also included. Muscle sympathetic nerve activity (MSNA; microneurography), mean arterial pressure (MAP; finger photoplethysmography) and minute ventilation (V˙E; pneumotachometer) were measured. Total MSNA (P = 1.000 and P = 0.616), MAP (P = 0.265) and V˙E (P = 0.587 and P = 0.472) were not different in men and women during eucapnia and during isocapnic hypoxia. Women exhibited attenuated increases in V˙E during hypercapnic hyperoxia (27.3 ± 6.3 vs. 39.5 ± 7.5 l/min, P < 0.0001) and hypercapnic hypoxia (40.9 ± 9.1 vs. 53.8 ± 13.3 l/min, P < 0.0001) compared with men. However, total MSNA responses were augmented in women (hypercapnic hyperoxia 378 ± 215 vs. 258 ± 107%, P = 0.017; hypercapnic hypoxia 607 ± 290 vs. 362 ± 268%, P < 0.0001). No sex differences in total MSNA, MAP or V˙E were observed during isocapnic hyperoxia and hypocapnic hyperoxia. Our results indicate that young women have augmented sympathetic responses to central chemoreflex activation, which explains the augmented MSNA response to combined central and peripheral chemoreflex activation. Key points Sex differences in the control of breathing have been well studied, but whether there are differences in the sympathetic neurocirculatory responses to chemoreflex activation between healthy women and men is incompletely understood. We observed that, compared with young men, young women displayed augmented increases in muscle sympathetic nerve activity during both hypercapnic hyperoxia (central chemoreflex activation) and hypercapnic hypoxia (central and peripheral chemoreflex activation) but had attenuated increases in minute ventilation. In contrast, no sex differences were found in either muscle sympathetic nerve activity or minute ventilation responses to isocapnic hypoxia (peripheral chemoreceptor stimulation). Young women have blunted ventilator, but augmented sympathetic responses, to central (hypercapnic hyperoxia) and combined central and peripheral chemoreflex activation (hypercapnic hypoxia), compared with young men. The possible causative association between the reduced ventilation and heightened sympathetic responses in young women awaits validation.
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Affiliation(s)
- Ana Luiza C Sayegh
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Jui-Lin Fan
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Lauro C Vianna
- NeuroV̇ASQ̇ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, DF, Brazil
| | - Mathew Dawes
- Department of Medicine, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - James P Fisher
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
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Abstract
Brain PCO2 is sensed primarily via changes in [H+]. Small pH changes are detected in the medulla oblongata and trigger breathing adjustments that help maintain arterial PCO2 constant. Larger perturbations of brain CO2/H+, possibly also sensed elsewhere in the CNS, elicit arousal, dyspnea, and stress, and cause additional breathing modifications. The retrotrapezoid nucleus (RTN), a rostral medullary cluster of glutamatergic neurons identified by coexpression of Phoxb and Nmb transcripts, is the lynchpin of the central respiratory chemoreflex. RTN regulates breathing frequency, inspiratory amplitude, and active expiration. It is exquisitely responsive to acidosis in vivo and maintains breathing autorhythmicity during quiet waking, slow-wave sleep, and anesthesia. The RTN response to [H+] is partly an intrinsic neuronal property mediated by proton sensors TASK-2 and GPR4 and partly a paracrine effect mediated by astrocytes and the vasculature. The RTN also receives myriad excitatory or inhibitory synaptic inputs including from [H+]-responsive neurons (e.g., serotonergic). RTN is silenced by moderate hypoxia. RTN inactivity (periodic or sustained) contributes to periodic breathing and, likely, to central sleep apnea. RTN development relies on transcription factors Egr2, Phox2b, Lbx1, and Atoh1. PHOX2B mutations cause congenital central hypoventilation syndrome; they impair RTN development and consequently the central respiratory chemoreflex.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States.
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
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Wang X, Luo J, Huang R, Xiao Y. The Elevated Central Chemosensitivity in Obstructive Sleep Apnea Patients with Hypertension. Nat Sci Sleep 2022; 14:855-865. [PMID: 35547180 PMCID: PMC9081185 DOI: 10.2147/nss.s362319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/20/2022] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Hypertension is a common comorbidity in obstructive sleep apnea (OSA), in which dysfunction of the autonomic nervous system plays an integral part. Chemoreflex is essential for ventilatory control and cardiovascular activity. This study aimed to determine whether central chemosensitivity was increased in OSA patients with hypertension and the potential role of the autonomic nerve activity in this relationship. PATIENTS AND METHODS A total of 77 men with OSA were included in this cross-sectional study. We measured hypercapnic ventilatory response (HCVR) by the rebreathing method under isoxic hyperoxia to test the central ventilatory chemosensitivity since hyperoxia silences the peripheral chemoreceptors' response to CO2. To elevate the autonomic nerve activity, time-domain, frequency-domain, and non-linear variables of heart rate variability were calculated over 5-min records. Univariate and multivariate linear regression analyses were used to find the determinants of HCVR. RESULTS The median HCVR was 2.3 (1.8, 3.3), 2.1 (1.6, 3.0), and 3 (2.2, 3.7) L/min/mmHg in all participants, OSA patients, and OSA patients with hypertension, respectively. Hypertension was significantly associated with elevated HCVR after adjusting for age, central obesity, OSA severity, daytime sleepiness, and diabetes mellitus. Compared with OSA patients, OSA patients with hypertension had higher body mass index, worse nocturnal hypoxia, and lower time-domain variables and frequency-domain variables. After adjusting for age, apnea-hypopnea index, central obesity, and beta-blocker usage, approximate entropy was independently negatively associated with HCVR in OSA patients with hypertension. CONCLUSION This study demonstrated elevated central chemosensitivity in OSA patients with hypertension. Compared with OSA patients, OSA patients with hypertension had attenuated parasympathetic nerve activity. This study preliminarily illustrated that elevated central chemosensitivity might be associated with weak adaptability of the cardiac autonomic nervous system in OSA patients with hypertension.
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Affiliation(s)
- Xiaona Wang
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Jinmei Luo
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Rong Huang
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Yi Xiao
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
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11
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Yilmaz A, Kalsbeek A, Buijs RM. Early changes of immunoreactivity to orexin in hypothalamus and to RFamide peptides in brainstem during the development of hypertension. Neurosci Lett 2021; 762:136144. [PMID: 34332031 DOI: 10.1016/j.neulet.2021.136144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/24/2021] [Accepted: 07/26/2021] [Indexed: 11/19/2022]
Abstract
Baroreflex sensitivity (BRS) is an important function of the nervous system and essential for maintaining blood pressure levels in the physiological range. In hypertension, BRS is decreased both in man and animals. Although increased sympathetic activity is thought to be the main cause of decreased BRS, hence the development of hypertension, the BRS is regulated by both sympathetic (SNS) and parasympathetic (PNS) nervous system. Here, we analyzed neuropeptide changes in the lateral hypothalamus (LH), which favours the SNS activity, as well as in PNS nuclei in the brainstem of spontaneously hypertensive rats (SHR) and their normotensive controls (Wistar Kyoto rats- WKY). The analyses revealed that in the WKY rats the hypothalamic orexin system, known for its role in sympathetic activation, showed a substantial decrease when animals age. At the same time, however, such a decrease was not observed when hypertension developed in the SHR. In contrast, Neuropeptide FF (NPFF) and Prolactin Releasing Peptide (PrRP) expression in the PNS associated Nucleus Tractus Solitarius (NTS) and Dorsal Motor Nucleus of the Vagus (DMV) diminished substantially, not only after the establishment of hypertension but also before its onset. Therefore, the current results indicate early changes in areas of the central nervous system involved in SNS and PNS control of blood pressure and associated with the development of hypertension.
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Affiliation(s)
- Ajda Yilmaz
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam 1105 BA, the Netherlands
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam 1105 BA, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Ruud M Buijs
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam 1105 BA, the Netherlands; Department of Cell Biology and Physiology, Institute for Biomedical Research, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
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12
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The role of sleep disorders in cardiovascular diseases: Culprit or accomplice? Life Sci 2021; 283:119851. [PMID: 34324916 DOI: 10.1016/j.lfs.2021.119851] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 07/02/2021] [Accepted: 07/20/2021] [Indexed: 11/24/2022]
Abstract
Sleep disorders frequently comorbid with several cardiovascular diseases (CVDs), attracting increasing scientific attention and interest. Sleep disorders include insomnia, sleep-disordered breathing, restless legs syndrome, etc. It is well known that inflammation, sympathetic activation, and endothelial dysfunction play critical roles in sleep disorders, all of which are predisposing factors for CVDs. The comorbidity of sleep disorders and CVDs may have a bidirectional relationship. Patients with CVDs may have a high incidence of sleep disorders and vice versa. This review focused on the comorbidity of sleep disorders and CVDs and discussed the potential pathophysiological mechanisms and therapeutic strategies. In addition to the existing mechanisms, this review summarized novel potential mechanisms underlying comorbidities, such as gut microbiota, orexin, and extracellular vesicles, which may provide a theoretical basis for further basic research and clinical investigations on improving therapeutic outcomes.
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13
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Gao HR, Wu ZJ, Wu SB, Gao HY, Wang J, Zhang JL, Zhou MQ. Roles of central orexinergic system on cardiovascular function and acupuncture on intervention of cardiovascular risk: Orexinergic system mediate the role of acupuncture? Neuropeptides 2021; 87:102132. [PMID: 33636511 DOI: 10.1016/j.npep.2021.102132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 01/09/2021] [Accepted: 02/11/2021] [Indexed: 12/26/2022]
Abstract
Central orexinergic system contributes to the regulation of cardiovascular function. Orexinergic neurons receiving projections of nerve fibers from multiple structures of brain which involved in control and regulation of cardiovascular function locate in hypothalamus, and their axon terminals widely project to various central structures where orexins receptors are expressed. Here, we summarize the present knowledge that describes the influence of central orexinergic system on cardiovascular activity, the relevance of dysfunction in central orexinergic system with hypertension and psychological stress induced cardiovascular reactivity which are serious risk factors for cardiovascular disease and cardiovascular death. We propose that central orexinergic system may be potentially important targets for the prevention of cardiovascular disease and cardiovascular death, and different orexinergic system involved neuronal circuits may be involved in distinct cardiovascular functions. Acupuncture having bidirectional regulatory ability and a much lower incidence of side effects can prevent disease. We review the improvement of acupuncture on hypertension and psychological stress induced cardiovascular reactivity. We think that acupuncture intervenes hypertension and psychological stress induced cardiovascular reactivity to prevent cardiovascular disease and cardiovascular death. We also summarize relation between acupuncture and central orexinergic system. We propose a hypothesis that acupuncture improve hypertension and psychological stress induced cardiovascular reactivity through regulating central orexinergic system. The knowledge is beneficial for the development of potential therapeutic targets and methods to prevent cardiovascular disease and cardiovascular death.
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Affiliation(s)
- He-Ren Gao
- Key Laboratory of Acupuncture and Moxibustion Foundation and Technology of Anhui Province, Research Institute of Acupuncture and Meridian, College of Acupuncture and Tuina, Anhui Academy of Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China.
| | - Zi-Jian Wu
- Key Laboratory of Acupuncture and Moxibustion Foundation and Technology of Anhui Province, Research Institute of Acupuncture and Meridian, College of Acupuncture and Tuina, Anhui Academy of Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China
| | - Sheng-Bing Wu
- Key Laboratory of Acupuncture and Moxibustion Foundation and Technology of Anhui Province, Research Institute of Acupuncture and Meridian, College of Acupuncture and Tuina, Anhui Academy of Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China; Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, China
| | - He-Yuan Gao
- Department of Pediatrics, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Jie Wang
- Key Laboratory of Acupuncture and Moxibustion Foundation and Technology of Anhui Province, Research Institute of Acupuncture and Meridian, College of Acupuncture and Tuina, Anhui Academy of Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China
| | - Jin-Li Zhang
- Anhui Vocational College of Grain Engineering, Hefei, China
| | - Mei-Qi Zhou
- Key Laboratory of Acupuncture and Moxibustion Foundation and Technology of Anhui Province, Research Institute of Acupuncture and Meridian, College of Acupuncture and Tuina, Anhui Academy of Chinese Medicine, Anhui University of Chinese Medicine, Hefei, China; Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, China; Bozhou Institute of Traditional Chinese Medicine, Anhui Academy of Chinese Medicine, Bozhou, China.
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14
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Tian Y, Geng D, Wang Y, Shi L, Yu H, He W, Zhu Y, Jun S, Fu C, Wang X, Zhang X, Yuan F, Wang S. Contribution of retrotrapezoid nucleus neurons to CO 2 -amplified cardiorespiratory activity in spontaneously hypertensive rats. J Physiol 2020; 599:1115-1130. [PMID: 33347681 DOI: 10.1113/jp280246] [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: 10/05/2020] [Accepted: 12/04/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS This study demonstrates that both CO2 -induced respiratory and cardiovascular responses are augmented in spontaneously hypertensive rats (SHRs). Genetic ablation of the retrotrapezoid nucleus (RTN) neurons depresses enhanced hypercapnic ventilatory response and eliminates CO2 -stimulated increase in arterial pressure and heart rate in SHRs. SHRs have a high protein level of pH-sensitive channels in the RTN, including the TASK-2 channel, Kv12.1 channel and acid-sensing ion channel 3. The inhibition of putative TASK-2 channel activity by clofilium diminishes amplified hypercapnic ventilatory and cardiovascular responses, and reduces the number of CO2 -activated RTN neurons in SHRs. These results indicate that RTN neurons contribute to enhanced CO2 -stimulated respiratory and cardiovascular responses in SHRs. ABSTRACT The respiratory regulation of cardiovascular activity is essential for maintaining an efficient ventilation and perfusion ratio. Activation of central respiratory chemoreceptors not only elicits a ventilatory response but also regulates sympathetic nerve activity and arterial blood pressure (ABP). The retrotrapezoid nucleus (RTN) is the most completely characterized cluster of central respiratory chemoreceptors. We hypothesize that RTN neurons contribute to augmented CO2 -stimulated respiratory and cardiovascular responses in adult spontaneously hypertensive rats (SHRs). Our findings indicate that SHRs exhibit more enhanced hypercapnic cardiorespiratory responses than age-matched normotensive Wistar-Kyoto rats. Genetic ablation of RTN neurons notably depresses an enhanced hypercapnic ventilatory response (HCVR) and eliminates a CO2 -stimulated greater increase in ABP and heart rate in SHRs. In addition, SHRs have a higher protein level of pH-sensitive channels in the RTN, including TASK-2 channels, Kv12.1 channels and acid-sensing ion channel 3. Administration of clofilium (i.p.), an unselective inhibitor of TASK-2 channels, not only significantly reduces the enhanced HCVR but also inhibits CO2 -amplified increases in ABP and heart rate in SHRs. Moreover, clofilium significantly decreases the number of CO2 -activated RTN neurons in SHRs. Taken together, we suggest that RTN neurons play an important role in enhanced hypercapnic ventilatory and cardiovascular responses in SHRs and the putative mechanism involved is associated with TASK-2 channel activity in the RTN.
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Affiliation(s)
- Yanming Tian
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Danyang Geng
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Yakun Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Luo Shi
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Hongxiao Yu
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Wei He
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Yufang Zhu
- School of Nursing, Hebei Medical University, Shijiazhuang, Hebei, 050000, China
| | - Shirui Jun
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Congrui Fu
- School of Nursing, Hebei Medical University, Shijiazhuang, Hebei, 050000, China
| | - Xin Wang
- Physiology Laboratory of Teaching Experiment Center, Hebei Medical University, Shijiazhuang, Hebei, 050000, China
| | - Xiangjian Zhang
- Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, Hebei, 050000, China
| | - Fang Yuan
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Sheng Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang, Hebei, 050017, China.,Hebei Key Laboratory of Neurophysiology, Shijiazhuang, Hebei, 050017, China
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15
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Nichols KE, Holliday-White KL, Bogie HM, Swearingen KM, Fine MS, Doyle J, Tiesma SR. Cardiovascular and Metabolic Responses to Carbon Dioxide Euthanasia in Conscious and Anesthetized Rats. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2020; 59:742-749. [PMID: 32873368 DOI: 10.30802/aalas-jaalas-19-000166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Euthanasia is a necessary component in research and must be conducted humanely. Currently, regulated CO₂ exposure in conscious rats is acceptable, but data are divided on whether CO₂ alone is more distressing than anesthesia prior to CO₂. To evaluate distress in rats, we compared physiologic responses to CO₂ euthanasia with and without isoflurane preanesthesia. Male Sprague-Dawley rats were implanted with telemetry devices to measure mean arterial pressure (MAP), heart rate (HR), and blood glucose. Animals recovered for 2 wk and were then exposed to either 5% isoflurane (n = 6) or 100% CO₂ (n = 7; calculated 30% chamber volume/min displacement) in their home cages to induce loss of consciousness. Euthanasia was then completed with CO₂ in both groups. MAP and HR increased when the gas delivery lids were placed on the home cages of both groups. Both MAP and HR gradually decreased with isoflurane exposure. MAP increased and HR decreased with CO₂ exposure. Glucose levels remained stable throughout the procedure, except for a small drop in conscious animals initially exposed to 100% CO₂. These data suggest that both gases affect the measured parameters in a similar manner, and that environmental factors, such as gas delivery lid placement, also change these measurements.
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Affiliation(s)
- Kathryn E Nichols
- Surgical Services, Data Sciences International, St Paul, Minnesota;,
| | | | - Heather M Bogie
- Surgical Services, Data Sciences International, St Paul, Minnesota
| | - Kim M Swearingen
- Surgical Services, Data Sciences International, St Paul, Minnesota; Envigo, Denver, Pennsylvania
| | - Megan S Fine
- Surgical Services, Data Sciences International, St Paul, Minnesota; Boston Scientific, St Paul, Minnesota
| | - Jennifer Doyle
- Data Services, Data Sciences International, St Paul, Minnesota
| | - Scott R Tiesma
- Marketing, Data Sciences International, St Paul, Minnesota; Medtronic, Minneapolis, Minnesota
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16
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Guyenet PG, Stornetta RL, Souza GMPR, Abbott SBG, Brooks VL. Neuronal Networks in Hypertension: Recent Advances. Hypertension 2020; 76:300-311. [PMID: 32594802 DOI: 10.1161/hypertensionaha.120.14521] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurogenic hypertension is associated with excessive sympathetic nerve activity to the kidneys and portions of the cardiovascular system. Here we examine the brain regions that cause heightened sympathetic nerve activity in animal models of neurogenic hypertension, and we discuss the triggers responsible for the changes in neuronal activity within these regions. We highlight the limitations of the evidence and, whenever possible, we briefly address the pertinence of the findings to human hypertension. The arterial baroreflex reduces arterial blood pressure variability and contributes to the arterial blood pressure set point. This set point can also be elevated by a newly described cerebral blood flow-dependent and astrocyte-mediated sympathetic reflex. Both reflexes converge on the presympathetic neurons of the rostral medulla oblongata, and both are plausible causes of neurogenic hypertension. Sensory afferent dysfunction (reduced baroreceptor activity, increased renal, or carotid body afferent) contributes to many forms of neurogenic hypertension. Neurogenic hypertension can also result from activation of brain nuclei or sensory afferents by excess circulating hormones (leptin, insulin, Ang II [angiotensin II]) or sodium. Leptin raises blood vessel sympathetic nerve activity by activating the carotid bodies and subsets of arcuate neurons. Ang II works in the lamina terminalis and probably throughout the brain stem and hypothalamus. Sodium is sensed primarily in the lamina terminalis. Regardless of its cause, the excess sympathetic nerve activity is mediated to some extent by activation of presympathetic neurons located in the rostral ventrolateral medulla or the paraventricular nucleus of the hypothalamus. Increased activity of the orexinergic neurons also contributes to hypertension in selected models.
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Affiliation(s)
- Patrice G Guyenet
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Ruth L Stornetta
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - George M P R Souza
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Stephen B G Abbott
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Virginia L Brooks
- Department of Chemical Physiology and Biochemistry, Oregon Health & Sciences University, Portland (V.L.B.)
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17
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Cui SY, Huang YL, Cui XY, Zhao HL, Hu X, Liu YT, Qin Y, Kurban N, Zhang YH. A common neuronal mechanism of hypertension and sleep disturbances in spontaneously hypertensive rats: Role of orexinergic neurons. Prog Neuropsychopharmacol Biol Psychiatry 2020; 100:109902. [PMID: 32109507 DOI: 10.1016/j.pnpbp.2020.109902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
Epidemiologic studies have shown that sleep disorders are associated with the development of hypertension. The present study investigated dynamic changes in sleep patterns during the development of hypertension across the lifespan in spontaneously hypertensive rats (SHRs) and the neural mechanism that underlies these comorbidities, with a focus on the orexinergic system. Blood pressure in rats was measured using a noninvasive blood pressure tail cuff. Sleep was monitored by electroencephalographic and electromyographic recordings. Immunohistochemistry was used to detect the density and activity of orexinergic neurons in the perifornical nucleus. Hcrt2-SAP (400 or 800 ng) was microinjected in the lateral hypothalamus to lesion orexinergic neurons. Compared with Wistar-Kyoto rats, SHRs exhibited various patterns of sleep disturbances. In SHRs, dynamic changes in hypersomnia in the rats' active phase was not synchronized with the development of hypertension, but hyperarousal in the inactive phase and difficulties in falling asleep were observed concurrently with the development of hypertension. Furthermore, the density and activity of orexinergic neurons in the perifornical nucleus were significantly higher in SHRs than in age-matched Wistar-Kyoto rats. The reduction of orexinergic neurons in the lateral hypothalamus partially ameliorated the development of hypertension and prevented difficulties in falling asleep in SHRs. These results indicate that although the correlation between sleep disturbances and hypertension is very complex, common mechanisms may underlie these comorbidities in SHRs. Overactivity of the orexin system may be one such common mechanism.
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Affiliation(s)
- Su-Ying Cui
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Yuan-Li Huang
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Xiang-Yu Cui
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Hui-Ling Zhao
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Xiao Hu
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Yu-Tong Liu
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Yu Qin
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Nurhumar Kurban
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China
| | - Yong-He Zhang
- Department of Pharmacology, Peking University, School of Basic Medical Science, 38 Xueyuan Road, Beijing 100191, China.
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18
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Barnett S, Li A. Orexin in Respiratory and Autonomic Regulation, Health and Diseases. Compr Physiol 2020; 10:345-363. [DOI: 10.1002/cphy.c190013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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19
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Loiseau C, Casciato A, Barka B, Cayetanot F, Bodineau L. Orexin Neurons Contribute to Central Modulation of Respiratory Drive by Progestins on ex vivo Newborn Rodent Preparations. Front Physiol 2019; 10:1200. [PMID: 31611806 PMCID: PMC6776592 DOI: 10.3389/fphys.2019.01200] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 09/03/2019] [Indexed: 11/13/2022] Open
Abstract
Dysfunction of central respiratory CO2/H+ chemosensitivity is a pivotal factor that elicits deep hypoventilation in patients suffering from central hypoventilation syndromes. No pharmacological treatment is currently available. The progestin desogestrel has been suggested to allow recovery of respiratory response to CO2/H+ in patients suffering from central hypoventilation, but except the fact that supramedullary regions may be involved, mechanisms are still unknown. Here, we tested in neonates whether orexin systems contribute to desogestrel’s central effects on respiratory function. Using isolated ex vivo central nervous system preparations from newborn rats, we show orexin and almorexant, an antagonist of orexin receptors, supressed strengthening of the increase in respiratory frequency induced by prolonged metabolic acidosis under exposure to etonogestrel, the active metabolite of desogestrel. In parallel, almorexant suppressed the increase and enhanced increase in c-fos expression in respiratory-related brainstem structures induced by etonogestrel. These results suggest orexin signalisation is a key component of acidosis reinforcement of respiratory drive by etonogestrel in neonates. Although stage of development used is different as that for progestin clinical observations, presents results provide clues about conditions under which desogestrel or etonogestrel may enhance ventilation in patients suffering from central hypoventilation syndromes.
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Affiliation(s)
- Camille Loiseau
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Alexis Casciato
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Besma Barka
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Florence Cayetanot
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Laurence Bodineau
- Institut National de la Santé et de la Recherche Médicale, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
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20
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Sabino JPJ, Soriano RN, Santos BM, Donatti AF, Fernandez RR, da Silva GS, Branco LG. Central administration of aminooxyacetate, an inhibitor of H2S production, affects thermoregulatory but not cardiovascular and ventilatory responses to hypercapnia in spontaneously hypertensive rats. Respir Physiol Neurobiol 2019; 263:38-46. [DOI: 10.1016/j.resp.2019.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/07/2019] [Accepted: 03/01/2019] [Indexed: 01/18/2023]
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21
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Huang SC, Li TL, Lee YH, Dai YWE, Chen YC, Hwang LL. Role of the orexin 2 receptor in palatable-food consumption-associated cardiovascular reactivity in spontaneously hypertensive rats. Sci Rep 2018; 8:12703. [PMID: 30140065 PMCID: PMC6107633 DOI: 10.1038/s41598-018-30970-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/31/2018] [Indexed: 01/19/2023] Open
Abstract
Hypertensive subjects often exhibit exaggerated cardiovascular reactivity. An overactive orexin system underlies the pathophysiology of hypertension. We examined orexin's roles in eating-associated cardiovascular reactivity in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats. Results showed eating regular chow or palatable food (sucrose agar) was accompanied by elevated arterial pressure and heart rate. In both SHRs and WKY rats, the cardiovascular responses associated with sucrose-agar consumption were greater than that with regular-chow consumption. Additionally, SHRs exhibited greater cardiovascular responses than WKY rats did to regular-chow and palatable food consumption. Central orexin 2 receptor (OX2R) blockade attenuated sucrose-agar consumption-associated cardiovascular response only in SHRs. In both SHRs and WKY rats, OX2R blockade did not affect regular-chow consumption-associated cardiovascular responses. Greater numbers of c-Fos-positive cells in the rostral ventrolateral medulla (RVLM) and of c-Fos-positive orexin neurons in the dorsomedial hypothalamus (DMH) were detected in sucrose agar-treated SHRs, compared to regular chow-treated SHRs and to sucrose agar-treated WKY rats. Central OX2R blockade reduced the number of c-Fos-positive cells in the RVLM only in sucrose agar-treated SHRs. We concluded that in SHRs, orexin neurons in the DMH might be overactive during eating palatable food and may further elicit exaggerated cardiovascular responses via an OX2R-RVLM pathway.
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Affiliation(s)
- Shang-Cheng Huang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Tzu-Ling Li
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yen-Hsien Lee
- Cheng-Jian Biomedical Company Limited, Taipei, Taiwan
| | - Yu-Wen E Dai
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yu-Chun Chen
- School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ling-Ling Hwang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan. .,Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
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22
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Saku K, Tohyama T, Shinoda M, Kishi T, Hosokawa K, Nishikawa T, Oga Y, Sakamoto T, Tsutsui H, Miyamoto T, Sunagawa K. Central chemoreflex activation induces sympatho-excitation without altering static or dynamic baroreflex function in normal rats. Physiol Rep 2017; 5:5/17/e13406. [PMID: 28899913 PMCID: PMC5599864 DOI: 10.14814/phy2.13406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 08/07/2017] [Indexed: 11/24/2022] Open
Abstract
Central chemoreflex activation induces sympatho-excitation. However, how central chemoreflex interacts with baroreflex function remains unknown. This study aimed to examine the impact of central chemoreflex on the dynamic as well as static baroreflex functions under open-loop conditions. In 15 anesthetized, vagotomized Sprague-Dawley rats, we isolated bilateral carotid sinuses and controlled intra-sinus pressure (CSP). We then recorded sympathetic nerve activity (SNA) at the celiac ganglia, and activated central chemoreflex by a gas mixture containing various concentrations of CO2 Under the baroreflex open-loop condition (CSP = 100 mmHg), central chemoreflex activation linearly increased SNA and arterial pressure (AP). To examine the static baroreflex function, we increased CSP stepwise from 60 to 170 mmHg and measured steady-state SNA responses to CSP (mechanoneural arc), and AP responses to SNA (neuromechanical arc). Central chemoreflex activation by inhaling 3% CO2 significantly increased SNA irrespective of CSP, indicating resetting of the mechanoneural arc, but did not change the neuromechanical arc. As a result, central chemoreflex activation did not change baroreflex maximum total loop gain significantly (-1.29 ± 0.27 vs. -1.68 ± 0.74, N.S.). To examine the dynamic baroreflex function, we randomly perturbed CSP and estimated transfer functions from 0.01 to 1.0 Hz. The transfer function of the mechanoneural arc approximated a high-pass filter, while those of the neuromechanical arc and total (CSP-AP relationship) arcs approximated a low-pass filter. In conclusion, central chemoreflex activation did not alter the transfer function of the mechanoneural, neuromechanical, or total arcs. Central chemoreflex modifies hemodynamics via sympatho-excitation without compromising dynamic or static baroreflex AP buffering function.
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Affiliation(s)
- Keita Saku
- Department of Advanced Risk Stratification for Cardiovascular Diseases, Center for Disruptive Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - Takeshi Tohyama
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masako Shinoda
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takuya Kishi
- Department of Advanced Risk Stratification for Cardiovascular Diseases, Center for Disruptive Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - Kazuya Hosokawa
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takuya Nishikawa
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yasuhiro Oga
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takafumi Sakamoto
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Tadayoshi Miyamoto
- Graduate School of Health Sciences, Morinomiya University of Medical Sciences, Osaka, Japan
| | - Kenji Sunagawa
- Department of Therapeutic Regulation of Cardiovascular Homeostasis, Center for Disruptive Cardiovascular Medicine Kyushu University, Fukuoka, Japan
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23
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Huber MJ, Chen QH, Shan Z. The Orexin System and Hypertension. Cell Mol Neurobiol 2017; 38:385-391. [PMID: 28349223 DOI: 10.1007/s10571-017-0487-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/18/2017] [Indexed: 12/18/2022]
Abstract
In this review, we focus on the role of orexin signaling in blood pressure control and its potential link to hypertension by summarizing evidence from several experimental animal models of hypertension. Studies using the spontaneously hypertensive rat (SHR) animal model of human essential hypertension show that pharmacological blockade of orexin receptors reduces blood pressure in SHRs but not in Wistar-Kyoto rats. In addition, increased activity of the orexin system contributes to elevated blood pressure and sympathetic nerve activity (SNA) in dark-active period Schlager hypertensive (BPH/2J) mice, another genetic model of neurogenic hypertension. Similar to these two models, Sprague-Dawley rats with stress-induced hypertension display an overactive central orexin system. Furthermore, upregulation of the orexin receptor 1 increases firing of hypothalamic paraventricular nucleus neurons, augments SNA, and contributes to hypertension in the obese Zucker rat, an animal model of obesity-related hypertension. Finally, we propose a hypothesis for the implication of the orexin system in salt-sensitive hypertension. All of this evidence, coupled with the important role of elevated SNA in increasing blood pressure, strongly suggests that hyperactivity of the orexin system contributes to hypertension.
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Affiliation(s)
- Michael J Huber
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA.
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