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Kulkarni SS, Mischel NA, Mueller PJ. Revisiting differential control of sympathetic outflow by the rostral ventrolateral medulla. Front Physiol 2023; 13:1099513. [PMID: 36733693 PMCID: PMC9887112 DOI: 10.3389/fphys.2022.1099513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 12/23/2022] [Indexed: 01/18/2023] Open
Abstract
The rostral ventrolateral medulla (RVLM) is an important brain region involved in both resting and reflex regulation of the sympathetic nervous system. Anatomical evidence suggests that as a bilateral structure, each RVLM innervates sympathetic preganglionic neurons on both sides of the spinal cord. However, the functional importance of ipsilateral versus contralateral projections from the RVLM is lacking. Similarly, during hypotension, the RVLM is believed to rely primarily on withdrawal of tonic gamma aminobutyric acid (GABA) inhibition to increase sympathetic outflow but whether GABA withdrawal mediates increased activity of functionally different sympathetic nerves is unknown. We sought to test the hypothesis that activation of the ipsilateral versus contralateral RVLM produces differential increases in splanchnic versus adrenal sympathetic nerve activities, as representative examples of functionally different sympathetic nerves. We also tested whether GABA withdrawal is responsible for hypotension-induced increases in splanchnic and adrenal sympathetic nerve activity. To test our hypothesis, we measured splanchnic and adrenal sympathetic nerve activity simultaneously in Inactin-anesthetized, male Sprague-Dawley rats during ipsilateral or contralateral glutamatergic activation of the RVLM. We also produced hypotension (sodium nitroprusside, i.v.) before and after bilateral blockade of GABAA receptors in the RVLM (bicuculline, 5 mM 90 nL). Glutamate (100 mM, 30 nL) injected into the ipsilateral or contralateral RVLM produced equivalent increases in splanchnic sympathetic nerve activity, but increased adrenal sympathetic nerve activity by more than double with ipsilateral injections versus contralateral injections (p < 0.05; n = 6). In response to hypotension, increases in adrenal sympathetic nerve activity were similar after bicuculline (p > 0.05), but splanchnic sympathetic nerve activity responses were eliminated (p < 0.05; n = 5). These results provide the first functional evidence that the RVLM has predominantly ipsilateral innervation of adrenal nerves. In addition, baroreflex-mediated increases in splanchnic but not adrenal sympathetic nerve activity are mediated by GABAA receptors in the RVLM. Our studies provide a deeper understanding of neural control of sympathetic regulation and insight towards novel treatments for cardiovascular disease involving sympathetic nervous system dysregulation.
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Miller DM, Joshi A, Kambouroglos ET, Engstrom IC, Bielanin JP, Wittman SR, McCall AA, Barman SM, Yates BJ. Responses of neurons in the rostral ventrolateral medulla of conscious cats to anticipated and passive movements. Am J Physiol Regul Integr Comp Physiol 2020; 318:R481-R492. [PMID: 31940234 PMCID: PMC7099461 DOI: 10.1152/ajpregu.00205.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/04/2019] [Accepted: 01/02/2020] [Indexed: 11/22/2022]
Abstract
The vestibular system contributes to regulating sympathetic nerve activity and blood pressure. Initial studies in decerebrate animals showed that neurons in the rostral ventrolateral medulla (RVLM) respond to small-amplitude (<10°) rotations of the body, as in other brain areas that process vestibular signals, although such movements do not affect blood distribution in the body. However, a subsequent experiment in conscious animals showed that few RVLM neurons respond to small-amplitude movements. This study tested the hypothesis that RVLM neurons in conscious animals respond to signals from the vestibular otolith organs elicited by large-amplitude static tilts. The activity of approximately one-third of RVLM neurons whose firing rate was related to the cardiac cycle, and thus likely received baroreceptor inputs, was modulated by vestibular inputs elicited by 40° head-up tilts in conscious cats, but not during 10° sinusoidal rotations in the pitch plane that affected the activity of neurons in brain regions providing inputs to the RVLM. These data suggest the existence of brain circuitry that suppresses vestibular influences on the activity of RVLM neurons and the sympathetic nervous system unless these inputs are physiologically warranted. We also determined that RVLM neurons failed to respond to a light cue signaling the movement, suggesting that feedforward cardiovascular responses do not occur before passive movements that require cardiovascular adjustments.
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Affiliation(s)
- Derek M Miller
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Asmita Joshi
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - Isaiah C Engstrom
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John P Bielanin
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Samuel R Wittman
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrew A McCall
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Susan M Barman
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Bill J Yates
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
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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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Subramanian M, Mueller PJ. Altered Differential Control of Sympathetic Outflow Following Sedentary Conditions: Role of Subregional Neuroplasticity in the RVLM. Front Physiol 2016; 7:290. [PMID: 27486405 PMCID: PMC4949265 DOI: 10.3389/fphys.2016.00290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/27/2016] [Indexed: 01/25/2023] Open
Abstract
Despite the classically held belief of an “all-or-none” activation of the sympathetic nervous system, differential responses in sympathetic nerve activity (SNA) can occur acutely at varying magnitudes and in opposing directions. Sympathetic nerves also appear to contribute differentially to various disease states including hypertension and heart failure. Previously we have reported that sedentary conditions enhanced responses of splanchnic SNA (SSNA) but not lumbar SNA (LSNA) to activation of the rostral ventrolateral medulla (RVLM) in rats. Bulbospinal RVLM neurons from sedentary rats also exhibit increased dendritic branching in rostral regions of the RVLM. We hypothesized that regionally specific structural neuroplasticity would manifest as enhanced SSNA but not LSNA following activation of the rostral RVLM. To test this hypothesis, groups of physically active (10–12 weeks on running wheels) or sedentary, male Sprague-Dawley rats were instrumented to record mean arterial pressure, LSNA and SSNA under Inactin anesthesia and during microinjections of glutamate (30 nl, 10 mM) into multiple sites within the RVLM. Sedentary conditions enhanced SSNA but not LSNA responses and SSNA responses were enhanced at more central and rostral sites. Results suggest that enhanced SSNA responses in rostral RVLM coincide with enhanced dendritic branching in rostral RVLM observed previously. Identifying structural and functional neuroplasticity in specific populations of RVLM neurons may help identify new treatments for cardiovascular diseases, known to be more prevalent in sedentary individuals.
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Affiliation(s)
- Madhan Subramanian
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
| | - Patrick J Mueller
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
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Xu LJ, Liu TT, He ZG, Hong QX, Xiang HB. Hypothesis: CeM-RVLM circuits may be implicated in sudden unexpected death in epilepsy by melanocortinergic-sympathetic signaling. Epilepsy Behav 2015; 45:124-7. [PMID: 25819799 DOI: 10.1016/j.yebeh.2015.02.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 02/25/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Li-Jun Xu
- Department of Cardiothroracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 Hubei, PR China
| | - Tao-Tao Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Zhi-Gang He
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Qing-Xiong Hong
- Department of Anesthesiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou 510120, PR China.
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
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Shang D, Xiong J, Xiang HB, Hao Y, Liu JH. Melanocortinergic circuits from medial vestibular nuclei to the kidney defined by transneuronal transport of pseudorabies virus. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:1996-2000. [PMID: 25973095 PMCID: PMC4396262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/28/2015] [Indexed: 06/04/2023]
Abstract
This study was designed to assess whether MC4R signaling existed in vestibular nuclei modulated the activity of kidney by a virally mediated transsynaptic tracing study. Pseudorabies virus (PRV)-614 was injected into the kidney in adult male MC4R-green fluorescent protein (GFP) transgenic mice (n = 5). After a survival time of 5 days, the mice were assigned to humanely sacrifice, and the brainstem were removed and sectioned, and processed for PRV-614 visualization. The neurochemical phenotype of MC4R-GFP-positive neurons was identified using fluorescence immunocytochemical labeling. PRV-614/MC4R-GFP dual labeled neurons were detected in medial vestibular nuclei. Our findings support the hypothesis that there exist melanocortinergic circuits from medial vestibular nuclei to the kidney.
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Affiliation(s)
- Dan Shang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology UniversityNo. 1277 Jiefang Ave, Wuhan 430022, People’s Republic of China
| | - Jun Xiong
- Hepatobiliary Surgery Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology UniversityNo. 1277 Jiefang Ave, Wuhan 430022, People’s Republic of China
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyNo. 1095 Jiefang Road, Wuhan 430030, People’s Republic of China
| | - Yan Hao
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyNo. 1095 Jiefang Road, Wuhan 430030, People’s Republic of China
| | - Jiu-Hong Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyNo. 1095 Jiefang Road, Wuhan 430030, People’s Republic of China
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Abstract
Evidence accumulated over 30 years, from experiments on animals and human subjects, has conclusively demonstrated that inputs from the vestibular otolith organs contribute to the control of blood pressure during movement and changes in posture. This review considers the effects of gravity on the body axis, and the consequences of postural changes on blood distribution in the body. It then separately considers findings collected in experiments on animals and human subjects demonstrating that the vestibular system regulates blood distribution in the body during movement. Vestibulosympathetic reflexes differ from responses triggered by unloading of cardiovascular receptors such as baroreceptors and cardiopulmonary receptors, as they can be elicited before a change in blood distribution occurs in the body. Dissimilarities in the expression of vestibulosympathetic reflexes in humans and animals are also described. In particular, there is evidence from experiments in animals, but not humans, that vestibulosympathetic reflexes are patterned, and differ between body regions. Results from neurophysiological and neuroanatomical studies in animals are discussed that identify the neurons that mediate vestibulosympathetic responses, which include cells in the caudal aspect of the vestibular nucleus complex, interneurons in the lateral medullary reticular formation, and bulbospinal neurons in the rostral ventrolateral medulla. Recent findings showing that cognition can modify the gain of vestibulosympathetic responses are also presented, and neural pathways that could mediate adaptive plasticity in the responses are proposed, including connections of the posterior cerebellar vermis with the vestibular nuclei and brainstem nuclei that regulate blood pressure.
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Affiliation(s)
- Bill J Yates
- Departments of Otolaryngology and Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
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Yue CJ, Feng L, Huang Q. RVLM-IML pathway may implicate controlling peripheral airways by melanocortinergic-sympathetic signaling: a transneuronal labeling study using pseudorabies virus. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2014; 7:7962-7966. [PMID: 25550839 PMCID: PMC4270583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/31/2014] [Indexed: 06/04/2023]
Abstract
Pseudorabies virus (PRV)-614 was injected into the tracheal wall of male MC4R-GFP transgenic mice, resulting in retrograde infections in spinal cord and autonomic premotor areas of the brain including the rostroventrolateral medulla (RVLM). This polysynaptic pathway to the airway may form the substrate underlying the impact of IML and RVLM on airway function. The neurochemical phenotype of MC4R-GFP-positive neurons was identified using fluorescence immunocytochemical labeling. PRV-614/MC4R-GFP dual labeled neurons were detected in spinal IML and the rostral ventrolateral medulla (RVLM). These data demonstrate the RVLM-IML pathway of synaptically connected neurons extending to the airway through melanocortinergic-sympathetic signaling.
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Affiliation(s)
- Cheng-Jin Yue
- Department of Anesthesiology, Maternal and Child Health Hospital of Hubei ProvinceWuhan 430070, Hubei, People’s Republic of China
| | - Li Feng
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, Hubei, People’s Republic of China
| | - Qi Huang
- Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430030, Hubei, People’s Republic of China
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