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Vavřínová A, Behuliak M, Vodička M, Bencze M, Ergang P, Vaněčková I, Zicha J. More efficient adaptation of cardiovascular response to repeated restraint in spontaneously hypertensive rats: the role of autonomic nervous system. Hypertens Res 2024; 47:2377-2392. [PMID: 38956283 PMCID: PMC11374672 DOI: 10.1038/s41440-024-01765-w] [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: 12/20/2023] [Revised: 05/15/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024]
Abstract
We hypothesized that sympathetic hyperactivity and parasympathetic insuficiency in spontaneously hypertensive rats (SHR) underlie their exaggerated cardiovascular response to acute stress and impaired adaptation to repeated restraint stress exposure compared to Wistar-Kyoto rats (WKY). Cardiovascular responses to single (120 min) or repeated (daily 120 min for 1 week) restraint were measured by radiotelemetry and autonomic balance was evaluated by power spectral analysis of systolic blood pressure variability (SBPV) and heart rate variability (HRV). Baroreflex sensitivity (BRS) was measured by the pharmacological Oxford technique. Stress-induced pressor response and vascular sympathetic activity (low-frequency component of SBPV) were enhanced in SHR subjected to single restraint compared to WKY, whereas stress-induced tachycardia was similar in both strains. SHR exhibited attenuated cardiac parasympathetic activity (high-frequency component of HRV) and blunted BRS compared to WKY. Repeated restraint did not affect the stress-induced increase in blood pressure. However, cardiovascular response during the post-stress recovery period of the 7th restraint was reduced in both strains. The repeatedly restrained SHR showed lower basal heart rate during the dark (active) phase and slightly decreased basal blood pressure during the light phase compared to stress-naive SHR. SHR subjected to repeated restraint also exhibited attenuated stress-induced tachycardia, augmented cardiac parasympathetic activity, attenuated vascular sympathetic activity and improved BRS during the last seventh restraint compared to single-stressed SHR. Thus, SHR exhibited enhanced cardiovascular and sympathetic responsiveness to novel stressor exposure (single restraint) compared to WKY. Unexpectedly, the adaptation of cardiovascular and autonomic responses to repeated restraint was more effective in SHR.
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Affiliation(s)
- Anna Vavřínová
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Michal Behuliak
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Martin Vodička
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Michal Bencze
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Peter Ergang
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Ivana Vaněčková
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Josef Zicha
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia.
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Marques SM, Melo MR, Zoccal DB, Menani JV, Colombari DSA, Ferreira-Neto ML, Xavier CH, Colombari E, Pedrino GR. Acute inhibition of nicotinamide adenine dinucleotide phosphate oxidase in the commissural nucleus of the solitary tract reduces arterial pressure and renal sympathetic nerve activity in renovascular hypertension. J Hypertens 2023; 41:1634-1644. [PMID: 37466439 DOI: 10.1097/hjh.0000000000003516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
BACKGROUND A growing body of evidence suggests that oxidative stress plays a role in the pathophysiology of hypertension. However, the involvement of the reactive oxygen species (ROS) in the commissural nucleus of the solitary tract (commNTS) in development the of hypertension remains unclear. METHOD We evaluated the hemodynamic and sympathetic responses to acute inhibition of NADPH oxidase in the commNTS in renovascular hypertensive rats. Under anesthesia, male Holtzman rats were implanted with a silver clip around the left renal artery to induce 2-kidney 1-clip (2K1C) hypertension. After six weeks, these rats were anesthetized and instrumented for recording mean arterial pressure (MAP), renal blood flow (RBF), renal vascular resistance (RVR), and renal sympathetic nerve activity (RSNA) during baseline and after injection of apocynin (nicotinamide adenine dinucleotide phosphate oxidase inhibitor), NSC 23766 (RAC inhibitor) or saline into the commNTS. RESULTS Apocynin into the commNTS decreased MAP, RSNA, and RVR in 2K1C rats. NSC 23766 into the commNTS decreased MAP and RSNA, without changing RVR in 2K1C rats. CONCLUSION These results demonstrate that the formation of ROS in the commNTS is important to maintain sympathoexcitation and hypertension in 2K1C rats and suggest that NADPH oxidase in the commNTS could be a potential target for therapeutics in renovascular hypertension.
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Affiliation(s)
- Stefanne M Marques
- Center for Neuroscience and Cardiovascular Research, Federal University of Goias, Goiania, GO
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
| | - Mariana R Melo
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
- Department of Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
| | - Marcos L Ferreira-Neto
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia
| | - Carlos H Xavier
- Systems Neurobiology Laboratory. Department of Physiological Sciences, Institute of Biological Science, Federal University of Goias, Goiania, GO, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University (UNESP), Araraquara, Brazil
| | - Gustavo R Pedrino
- Center for Neuroscience and Cardiovascular Research, Federal University of Goias, Goiania, GO
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Chemogenetic inhibition of Phox2-expressing neurons in the commissural NTS decreases blood pressure in anesthetized spontaneously hypertensive rats. Neurosci Lett 2022; 787:136817. [PMID: 35905886 DOI: 10.1016/j.neulet.2022.136817] [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: 03/27/2022] [Revised: 07/17/2022] [Accepted: 07/22/2022] [Indexed: 11/21/2022]
Abstract
Interruption of the activity of neurons in the commissural portion of the nucleus of the solitary tract (cNTS) decreases blood pressure (BP) in experimental models of hypertension, such as the spontaneously hypertensive (SH) rat. To examine whether PHOX2B expressing cNTS neurons are involved in maintaining the elevated BP, we used replication-deficient viruses with a modified Phox2 binding site promoter to express the inhibitory chemogenetic allatostatin receptor or green fluorescent protein in the cNTS. Following administration of allatostatin, we observed a depressor and bradycardic response in anesthetized SH rats that expressed the allatostatin receptor. Injection of allatostatin did not affect BP or heart rate (HR) in control SH rats expressing green fluorescent protein in the cNTS. Immunohistochemistry showed that the majority of transduced cNTS neurons were PHOX2B-immunoreactive and some also expressed tyrosine hydroxylase. We conclude that in anesthetized SH rat, the Phox2B expressing cNTS neurons maintain elevated BP.
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Importance of the commissural nucleus of the solitary tract in renovascular hypertension. Hypertens Res 2019; 42:587-597. [PMID: 30622315 DOI: 10.1038/s41440-018-0190-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 10/05/2018] [Accepted: 10/09/2018] [Indexed: 12/12/2022]
Abstract
The rodent renovascular hypertension model has been used to investigate the mechanisms promoting hypertension. The importance of the carotid body for renovascular hypertension has been demonstrated. As the commissural NTS (cNTS) is the first synaptic site in the central nervous system that receives information from carotid body chemoreceptors, we evaluated the contribution of cNTS to renovascular hypertension in the present study. Normotensive male Holtzman rats were implanted with a silver clip around the left renal artery to induce two-kidney, one-clip (2K1C) hypertension. Six weeks later, isoguvacine (a GABAA agonist) or losartan (an AT1 antagonist) was injected into the cNTS, and the effects were compared with carotid body removal. Immunohistochemistry for Iba-1 and GFAP to label microglia and astrocytes, respectively, and RT-PCR for components of the renin-angiotensin system and cytokines in the NTS were also performed 6 weeks after renal surgery. The inhibition of cNTS with isoguvacine or the blockade of AT1 receptors with losartan in the cNTS decreased the blood pressure and heart rate of 2K1C rats even more than carotid body removal did. The mRNA expression of NOX2, TNF-α and IL-6, microglia, and astrocytes also increased in the cNTS of 2K1C rats compared to that of normotensive rats. These results indicate that tonically active neurons within the cNTS are essential for the maintenance of hypertension in 2K1C rats. In addition to signals from the carotid body, the present results suggest that angiotensin II directly activates the cNTS and may also induce microgliosis and astrogliosis within the NTS, which, in turn, cause oxidative stress and neuroinflammation.
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Maglione AV, Taranto P, Hamermesz B, Souza JS, Cafarchio EM, Ogihara CA, Maciel RMB, Giannocco G, Sato MA. Impact of swimming exercise on inflammation in medullary areas of sympathetic outflow control in spontaneously hypertensive rats. Metab Brain Dis 2018; 33:1649-1660. [PMID: 29946957 DOI: 10.1007/s11011-018-0273-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 06/19/2018] [Indexed: 02/07/2023]
Abstract
Exercise reduces sympathetic activity (SA), arterial pressure and heart rate in spontaneously hypertensive rats (SHR). Exercise increases oxidative stress (OS) and inflammation is implicated in the generation of reactive oxygen species (ROS) and progression of hypertension. To unravel these effects of exercise and considering that SA is driven by medullary areas, we hypothesized that swimming exercise (SW) affects the gene expression (g.e.) of proteins involved in inflammation and OS in the commissural Nucleus of the Solitary Tract (cNTS) and Rostral ventrolateral medulla (RVLM), which control the sympathetic outflow in SHR. We used male SHR and Wistar rats (14-16wks-old) which were maintained sedentary (SED) or submitted to SW (1 h/day, 5 days/wk./6wks). The g.e. of cycloxygenase-2 (COX-2), interleukin 6 (IL-6), interleukin 10 (IL-10), AT-1 receptor (AT-1r), neuroglobin (Ngb) and cytoglobin (Ctb) in cNTS and RVLM was carried out by qPCR. We observed that COX-2 g.e. increased in SW-SHR in cNTS and RVLM compared to SED-SHR. The IL-6 g.e. reduced in RVLM in SW-SHR, whereas IL-10 g.e. increased in SW-SHR in comparison to SED-SHR. The AT-1r g.e. decreased in SW-SHR in cNTS and RVLM compared to SED-SHR. The Ngb and Ctb g.e. in cNTS neurons increased in SHR and Wistar rats submitted to SW compared to SED, but only Ctb g.e. increased in RVLM in SW-SHR and Wistar in comparison to SED. Therefore, the SW altered the g.e. in cNTS and RVLM for reducing the inflammation and ROS formation, which is increased particularly in SHR, consequently decreasing the OS.
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Affiliation(s)
- Andrea V Maglione
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil
| | - Patrícia Taranto
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil
| | - Bruno Hamermesz
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil
| | - Janaina S Souza
- Department of Medicine, Federal Univesity of Sao Paulo, Sao Paulo, SP, Brazil
| | - Eduardo M Cafarchio
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil
| | - Cristiana A Ogihara
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil
| | - Rui M B Maciel
- Department of Medicine, Federal Univesity of Sao Paulo, Sao Paulo, SP, Brazil
| | - Gisele Giannocco
- Department of Medicine, Federal Univesity of Sao Paulo, Sao Paulo, SP, Brazil
| | - Monica A Sato
- Department of Morphology and Physiology, Faculdade de Medicina do ABC, 2000 Lauro Gomes Ave., Vila Sacadura Cabral, Santo Andre, SP, 09060-870, Brazil.
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Sá RWM, Haibara AS, Gomes PM, Aguiar GL, Nascimento RSL, Pedrosa ML, Alzamora AC, de Oliveira LB, Cardoso LM. Changes in cardiovascular responses to chemoreflex activation of rats recovered from protein restriction are not related to AT 1 receptors. Exp Physiol 2017; 102:34-47. [PMID: 27763697 DOI: 10.1113/ep085791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 10/17/2016] [Indexed: 12/18/2022]
Abstract
NEW FINDINGS What is the central question of this study? In this study, we sought to investigate whether cardiovascular responses to peripheral chemoreflex activation of rats recovered from protein restriction are related to activation of AT1 receptors. What is the main finding and its importance? This study highlights the fact that angiotensinergic mechanisms activated by AT1 receptors do not support increased responses to peripheral chemoreflex activation by KCN in rats recovered from protein restriction. Also, we found that protein restriction led to increased resting ventilation in adult rats, even after recovery. The effects of a low-protein diet followed by recovery on cardiorespiratory responses to peripheral chemoreflex activation were tested before and after systemic angiotensin II type 1 (AT1 ) receptor antagonism. Male Fischer rats were divided into control and recovered (R-PR) groups after weaning. The R-PR rats were fed a low-protein (8%) diet for 35 days and recovered with a normal protein (20%) diet for 70 days. Control rats received a normal protein diet for 105 days (CG105 ). After cannulation surgery, mean arterial pressure, heart rate, respiratory frequency, tidal volume and minute ventilation were acquired using a digital recording system in freely moving rats. The role of angintensin II was evaluated by systemic antagonism of AT1 receptors with losartan (20 mg kg-1 i.v.). The peripheral chemoreflex was elicited by increasing doses of KCN (20-160 μg kg min-1 , i.v.). At baseline, R-PR rats presented increased heart rate and minute ventilation (372 ± 34 beats min-1 and 1.274 ± 377 ml kg-1 min-1 ) compared with CG105 animals (332 ± 22 beats min-1 and 856 ± 112 ml kg-1 min-1 ). Mean arterial pressure was not different between the groups. Pressor and bradycardic responses evoked by KCN (60 μg kg-1 ) were increased in R-PR (+45 ± 13 mmHg and -77 ± 47 beats min-1 ) compared with CG105 rats (+25 ± 17 mmHg and -27 ± 28 beats min-1 ), but no difference was found in the tachypnoeic response. These differences were preserved after losartan. The data suggest that angiotensin II acting on AT1 receptors may not be associated with the increased heart rate, increased minute ventilation and acute cardiovascular responses to peripheral chemoreflex activation in rats that underwent postweaning protein restriction followed by recovery.
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Affiliation(s)
- Renato Willian Martins Sá
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Andrea Siqueira Haibara
- Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais, 31, 270-910, Belo Horizonte, MG, Brazil
| | - Paula Magalhães Gomes
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Giovana Lopes Aguiar
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Rafael Souza Leopoldino Nascimento
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Maria Lucia Pedrosa
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Andréia Carvalho Alzamora
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Lisandra Brandino de Oliveira
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
| | - Leonardo Máximo Cardoso
- Department of Biological Sciences, ICEB/NUPEB, Federal University of Ouro Preto - Campus Universitário Morro do Cruzeiro, 35, 400-000, Ouro Preto, MG, Brazil
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Zoccal DB, Furuya WI, Bassi M, Colombari DSA, Colombari E. The nucleus of the solitary tract and the coordination of respiratory and sympathetic activities. Front Physiol 2014; 5:238. [PMID: 25009507 PMCID: PMC4070480 DOI: 10.3389/fphys.2014.00238] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/09/2014] [Indexed: 12/15/2022] Open
Abstract
It is well known that breathing introduces rhythmical oscillations in the heart rate and arterial pressure levels. Sympathetic oscillations coupled to the respiratory activity have been suggested as an important homeostatic mechanism optimizing tissue perfusion and blood gas uptake/delivery. This respiratory-sympathetic coupling is strengthened in conditions of blood gas challenges (hypoxia and hypercapnia) as a result of the synchronized activation of brainstem respiratory and sympathetic neurons, culminating with the emergence of entrained cardiovascular and respiratory reflex responses. Studies have proposed that the ventrolateral region of the medulla oblongata is a major site of synaptic interaction between respiratory and sympathetic neurons. However, other brainstem regions also play a relevant role in the patterning of respiratory and sympathetic motor outputs. Recent findings suggest that the neurons of the nucleus of the solitary tract (NTS), in the dorsal medulla, are essential for the processing and coordination of respiratory and sympathetic responses to hypoxia. The NTS is the first synaptic station of the cardiorespiratory afferent inputs, including peripheral chemoreceptors, baroreceptors and pulmonary stretch receptors. The synaptic profile of the NTS neurons receiving the excitatory drive from afferent inputs is complex and involves distinct neurotransmitters, including glutamate, ATP and acetylcholine. In the present review we discuss the role of the NTS circuitry in coordinating sympathetic and respiratory reflex responses. We also analyze the neuroplasticity of NTS neurons and their contribution for the development of cardiorespiratory dysfunctions, as observed in neurogenic hypertension, obstructive sleep apnea and metabolic disorders.
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Affiliation(s)
- Daniel B Zoccal
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Werner I Furuya
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Mirian Bassi
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry of Araraquara, São Paulo State University (UNESP) Araraquara, Brazil
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Blanch GT, Freiria-Oliveira AH, Speretta GFF, Carrera EJ, Li H, Speth RC, Colombari E, Sumners C, Colombari DSA. Increased expression of angiotensin II type 2 receptors in the solitary-vagal complex blunts renovascular hypertension. Hypertension 2014; 64:777-83. [PMID: 24958505 DOI: 10.1161/hypertensionaha.114.03188] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II increases and decreases arterial pressure by acting at angiotensin type 1 and type 2 receptors, respectively. Renovascular hypertensive rats exhibit a high level of activity of the peripheral and central renin-angiotensin system. Therefore, in the present study, we evaluated the effect of increasing the expression of angiotensin type 2 receptors in the solitary-vagal complex (nucleus of the solitary tract/dorsal motor nucleus of the vagus), a key brain stem region for cardiovascular regulation, on the development of renovascular hypertension. Holtzman normotensive rats were implanted with a silver clip around the left renal artery to induce 2-kidney 1-clip renovascular hypertension. Three weeks later, rats were microinjected in the solitary-vagal complex with either an adenoassociated virus to increase the expression of angiotensin type 2 receptors or with a control vector. We observed that increasing angiotensin type 2 receptor expression in the solitary-vagal complex attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex and the increase in the low-frequency component of systolic blood pressure observed in renovascular hypertensive rats. Furthermore, an observed decrease in mRNA levels of angiotensin-converting enzyme 2 in the solitary-vagal complex of renovascular hypertensive rats was restored to control levels after viral-mediated increases in angiotensin type 2 receptors at this site. Collectively, these data demonstrate specific and beneficial effects of angiotensin type 2 receptors via the brain of hypertensive rats and suggest that central angiotensin type 2 receptors may be a potential target for therapeutics in renovascular hypertension.
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Affiliation(s)
- Graziela Torres Blanch
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - André Henrique Freiria-Oliveira
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Guilherme Fleury Fina Speretta
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Eduardo J Carrera
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Hongwei Li
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Robert C Speth
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Eduardo Colombari
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.)
| | - Colin Sumners
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.).
| | - Débora S A Colombari
- From the Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil (G.T.B., A.H.F.-O., G.F.F.S., E.C., D.S.A.C.); Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL (E.J.C., R.C.S.); School of Biotechnology, Southern Medical University, Guangzhou, China (H.L.); and Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville (C.S., R.C.S.).
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Ogihara CA, Schoorlemmer GHM, Lazari MDFM, Giannocco G, Lopes OU, Colombari E, Sato MA. Swimming exercise changes hemodynamic responses evoked by blockade of excitatory amino receptors in the rostral ventrolateral medulla in spontaneously hypertensive rats. BIOMED RESEARCH INTERNATIONAL 2014; 2014:487129. [PMID: 24696852 PMCID: PMC3947672 DOI: 10.1155/2014/487129] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/06/2014] [Accepted: 01/07/2014] [Indexed: 02/07/2023]
Abstract
Exercise training reduces sympathetic activity in hypertensive humans and rats. We hypothesized that the swimming exercise would change the neurotransmission in the rostral ventrolateral medulla (RVLM), a key region involved in sympathetic outflow, and hemodynamic control in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Bilateral injections of kynurenic acid (KYN) were carried out in the RVLM in sedentary- (S-) or exercised- (E-) SHR and WKY rats submitted to swimming for 6 weeks. Rats were α-chloralose anesthetized and artificially ventilated, with Doppler flow probes around the lower abdominal aorta and superior mesenteric artery. Injections into the RVLM were made before and after i.v. L-NAME (nitric oxide synthase, NOS, inhibitor). Injections of KYN into the RVLM elicited a major vasodilation in the hindlimb more than in the mesenteric artery in E-SHR compared to S-SHR, but similar decrease in arterial pressure was observed in both groups. Injections of KYN into the RVLM after i.v. L-NAME attenuated the hindlimb vasodilation evoked by KYN and increased the mesenteric vasodilation in E-SHR. Swimming exercise can enhance the hindlimb vasodilation mediated by peripheral NO release, reducing the activation of neurons with EAA receptors in the RVLM in SHR.
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Affiliation(s)
- Cristiana A. Ogihara
- Department of Physiology, Faculdade de Medicina do ABC (FMABC), Avenida Principe de Gales 821, Vila Principe de Gales, 09060-650 Santo Andre, SP, Brazil
- Department of Physiology, Federal University of Sao Paulo (UNIFESP), Rua Botucatu 862, Vila Clementino, 04023-901 Sao Paulo, SP, Brazil
| | - Gerhardus H. M. Schoorlemmer
- Department of Physiology, Federal University of Sao Paulo (UNIFESP), Rua Botucatu 862, Vila Clementino, 04023-901 Sao Paulo, SP, Brazil
| | - Maria de Fátima M. Lazari
- Department of Pharmacology, Federal University of Sao Paulo (UNIFESP), Rua Tres de Maio 100, Vila Clementino, 04044-020 Sao Paulo, SP, Brazil
| | - Gisele Giannocco
- Department of Physiology, Faculdade de Medicina do ABC (FMABC), Avenida Principe de Gales 821, Vila Principe de Gales, 09060-650 Santo Andre, SP, Brazil
| | - Oswaldo U. Lopes
- Department of Physiology, Federal University of Sao Paulo (UNIFESP), Rua Botucatu 862, Vila Clementino, 04023-901 Sao Paulo, SP, Brazil
| | - Eduardo Colombari
- Department of Pathology and Physiology, School of Dentistry, Sao Paulo State University (UNESP), Rua Humaita 1680, Centro, 14801-385 Araraquara, SP, Brazil
| | - Monica A. Sato
- Department of Physiology, Faculdade de Medicina do ABC (FMABC), Avenida Principe de Gales 821, Vila Principe de Gales, 09060-650 Santo Andre, SP, Brazil
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Moreira TS, Menani JV, Colombari E, Takakura AC. Is carotid body input the only critical mechanism involved in hypertension in spontaneously hypertensive rat? J Physiol 2013; 591:745-6. [PMID: 23378425 PMCID: PMC3577552 DOI: 10.1113/jphysiol.2012.244640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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11
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Blanch GT, Freiria-Oliveira AH, Murphy D, Paulin RF, Antunes-Rodrigues J, Colombari E, Menani JV, Colombari DSA. Inhibitory mechanism of the nucleus of the solitary tract involved in the control of cardiovascular, dipsogenic, hormonal, and renal responses to hyperosmolality. Am J Physiol Regul Integr Comp Physiol 2013; 304:R531-42. [PMID: 23364528 DOI: 10.1152/ajpregu.00191.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nucleus of the solitary tract (NTS) is the primary site of visceral afferents to the central nervous system. In the present study, we investigated the effects of lesions in the commissural portion of the NTS (commNTS) on the activity of vasopressinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei, plasma vasopressin, arterial pressure, water intake, and sodium excretion in rats with plasma hyperosmolality produced by intragastric 2 M NaCl (2 ml/rat). Male Holtzman rats with 15-20 days of sham or electrolytic lesion (1 mA; 10 s) of the commNTS were used. CommNTS lesions enhanced a 2 M NaCl intragastrically induced increase in the number of vasopressinergic neurons expressing c-Fos in the PVN (28 ± 1, vs. sham: 22 ± 2 c-Fos/AVP cells) and SON (26 ± 4, vs. sham: 11 ± 1 c-Fos/AVP cells), plasma vasopressin levels (21 ± 8, vs. sham: 6.6 ± 1.3 pg/ml), pressor responses (25 ± 7 mmHg, vs. sham: 7 ± 2 mmHg), water intake (17.5 ± 0.8, vs. sham: 11.2 ± 1.8 ml/2 h), and natriuresis (4.9 ± 0.8, vs. sham: 1.4 ± 0.3 meq/1 h). The pretreatment with vasopressin antagonist abolished the pressor response to intragastric 2 M NaCl in commNTS-lesioned rats (8 ± 2.4 mmHg at 10 min), suggesting that this response is dependent on vasopressin secretion. The results suggest that inhibitory mechanisms dependent on commNTS act to limit or counterbalance behavioral, hormonal, cardiovascular, and renal responses to an acute increase in plasma osmolality.
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Affiliation(s)
- Graziela T Blanch
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil
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Freiria-Oliveira AH, Blanch GT, Li H, Colombari E, Colombari DSA, Sumners C. Macrophage migration inhibitory factor in the nucleus of solitary tract decreases blood pressure in SHRs. Cardiovasc Res 2012; 97:153-60. [PMID: 22997157 DOI: 10.1093/cvr/cvs297] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS The macrophage migration inhibitory factor (MIF) is an intracellular inhibitor of the central nervous system actions of angiotensin II on blood pressure. Considering that angiotensin II actions at the nucleus of the solitary tract are important for the maintenance of hypertension in spontaneously hypertensive rats (SHRs), we tested if increased MIF expression in the nucleus of the solitary tract of SHR alters the baseline high blood pressure in these rats. METHODS AND RESULTS Eight-week-old SHRs or normotensive rats were microinjected with the vector AAV2-CBA-MIF into the nucleus of the solitary tract, resulting in MIF expression predominantly in neurons. Rats also underwent recordings of the mean arterial blood pressure (MAP) and heart rate (via telemetry devices implanted in the abdominal aorta), cardiac- and baroreflex function. Injections of AAV2-CBA-MIF into the nucleus of the solitary tract of SHRs produced significant decreases in the MAP, ranging from 10 to 20 mmHg, compared with age-matched SHRs that had received identical microinjections of the control vector AAV2-CBA-eGFP. This lowered MAP in SHRs was maintained through the end of the experiment at 31 days, and was associated with an improvement in baroreflex function to values observed in normotensive rats. In contrast to SHRs, similar increased MIF expression in the nucleus of the solitary tract of normotensive rats produced no changes in baseline MAP and baroreflex function. CONCLUSION These results indicate that an increased expression of MIF within the nucleus of the solitary tract neurons of SHRs lowers blood pressure and restores baroreflex function.
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Affiliation(s)
- André Henrique Freiria-Oliveira
- Department of Physiology and Functional Genomics and McKnight Brain Institute, College of Medicine, University of Florida, 1600 Southwest Archer Road, PO-BOX: 100274, Gainesville, FL 32610, USA
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Vieira AA, De Luca LA, Colombari E, Colombari DS, Menani JV. Commissural NTS lesions enhance the pressor response to central cholinergic and adrenergic activation. Neurosci Lett 2012; 521:31-6. [DOI: 10.1016/j.neulet.2012.05.053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 05/03/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
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Gerrits PO, Kortekaas R, Veening JG, de Weerd H, van der Want JJL. Reduced aging defects in estrogen receptive brainstem nuclei in the female hamster. Neurobiol Aging 2012; 33:2920-34. [PMID: 22445324 DOI: 10.1016/j.neurobiolaging.2012.02.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 02/15/2012] [Accepted: 02/15/2012] [Indexed: 10/28/2022]
Abstract
UNLABELLED The nucleus pararetroambiguus (NPRA) and the commissural nucleus of the solitary tract (NTScom) show estrogen nuclear receptor-α immunoreactivity (nuclear ER-α-IR). Both cell groups are involved in estrous cycle related adaptations. We examined in normally cycling aged hamsters the occurrence/amount/frequency of age-related degenerative changes in NPRA and NTScom during estrus and diestrus. In 2640 electron microscopy photomicrographs plasticity reflected in the ratio of axon terminal surface/dendrite surface (t/d) was morphometrically analyzed. Medial tegmental field (mtf, nuclear ER-α-IR poor), served as control. In aged animals, irrespective of nuclear ER-α-IR+ or nuclear ER-α-IR- related cell groups, extensive diffuse degenerative structural aberrations were observed. The hormonal state had a strong influence on t/d ratios in NPRA and NTScom, but not in mtf. In NPRA and NTScom, diestrous hamsters had significantly smaller t/d ratios (NPRA, 0.750 ± 0.050; NTScom, 0.900 ± 0.039) than the estrous hamsters (NPRA, 1.083 ± 0.075; NTScom, 1.204 ± 0.076). Aging affected axodendritic ratios only in mtf (p < 0.001). IN CONCLUSION in the female hamster brain, estrous cycle-induced structural plasticity is preserved in NPRA and NTScom during aging despite the presence of diffuse age-related neurodegenerative changes.
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Affiliation(s)
- Peter O Gerrits
- Department of Neuroscience, Section of Anatomy, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Ogihara CA, Schoorlemmer GHM, Levada AC, Pithon-Curi TC, Curi R, Lopes OU, Colombari E, Sato MA. Exercise changes regional vascular control by commissural NTS in spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2010; 299:R291-7. [DOI: 10.1152/ajpregu.00055.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Inhibition of the commissural nucleus of the solitary tract (commNTS) induces a fall in sympathetic nerve activity and blood pressure in spontaneously hypertensive rats (SHR), which suggests that this subnucleus of the NTS is a source of sympathoexcitation. Exercise training reduces sympathetic activity and arterial pressure. The purpose of the present study was to investigate whether the swimming exercise can modify the regional vascular responses evoked by inhibition of the commNTS neurons in SHR and normotensive Wistar-Kyoto (WKY) rats. Exercise consisted of swimming, 1 h/day, 5 days/wk for 6 wks, with a load of 2% of the body weight. The day after the last exercise session, the rats were anesthetized with intravenous α-chloralose, tracheostomized, and artificially ventilated. The femoral artery was cannulated for mean arterial pressure (MAP) and heart rate recordings, and Doppler flow probes were placed around the lower abdominal aorta and superior mesenteric artery. Microinjection of 50 mM GABA into the commNTS caused similar reductions in MAP in swimming and sedentary SHR (−25 ± 6 and −30 ± 5 mmHg, respectively), but hindlimb vascular conductance increased twofold in exercised vs. sedentary SHR (54 ± 8 vs. 24 ± 5%). GABA into the commNTS caused smaller reductions in MAP in swimming and sedentary WKY rats (−20 ± 4 and −16 ± 2 mmHg). Hindlimb conductance increased fourfold in exercised vs. sedentary WKY rats (75 ± 2% vs. 19 ± 3%). Therefore, our data suggest that the swimming exercise induced changes in commNTS neurons, as shown by a greater enhancement of hindlimb vasodilatation in WKY vs. SHR rats in response to GABAergic inhibition of these neurons.
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Affiliation(s)
| | | | - Adriana C. Levada
- Department of Physiology, Biomedical Sciences Institute–University of Sao Paulo, Sao Paulo, Brazil; and
| | - Tania C. Pithon-Curi
- Department of Physiology, Biomedical Sciences Institute–University of Sao Paulo, Sao Paulo, Brazil; and
| | - Rui Curi
- Department of Physiology, Biomedical Sciences Institute–University of Sao Paulo, Sao Paulo, Brazil; and
| | | | - Eduardo Colombari
- Department of Physiology, Federal University of Sao Paulo, Sao Paulo, Brazil
- Faculdade de Medicina do ABC, Santo Andre, Brazil
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16
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Moreira TS, Takakura AC, Colombari E, Menani JV. Antihypertensive effects of central ablations in spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1797-806. [DOI: 10.1152/ajpregu.90730.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Commissural nucleus of the solitary tract (commNTS) lesions transitorily (first 5 days) reduce mean arterial pressure (MAP) in spontaneously hypertensive rats (SHR), and lesions of the tissue surrounding the anteroventral third ventricle (AV3V region) chronically reduce MAP in other models of hypertension. In the present study, we investigated the effects of combined AV3V+commNTS electrolytic lesions on MAP and heart rate (HR) in conscious SHR. Baseline MAP and HR were recorded in male SHR before and for the next 40 days after sham or AV3V lesions combined with sham or commNTS lesions. The AV3V lesions produced no change in MAP in SHR, while commNTS lesions reduced MAP acutely (121 ± 2 to 127 ± 3 mmHg in the 1st and 5th days, respectively, vs. prelesion: 192 ± 4 mmHg) but not chronically (from 10 to 40 days). However, combined AV3V+commNTS lesions reduced MAP of SHR chronically (119 ± 2 to 161 ± 4 mmHg, in the 1st and 40th day, respectively, vs. prelesion levels: 186 ± 4 mmHg) or sham-lesioned SHR (187 ± 4 to 191 ± 6 mmHg). Sympathetic and angiotensinergic blockade produced less reduction in MAP in SHR with AV3V+commNTS-lesions, and there was no relationship between changes on water and food intake, body weight, or urinary excretion produced by AV3V+commNTS lesions with the changes in MAP. The present findings suggest that in the absence of the commNTS, the AV3V region contributes to the hypertension observed in SHR by mechanisms that appear to involve enhanced angiotensinergic and sympathetic activity.
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17
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Brozoski DT, Dean C, Hopp FA, Hillard CJ, Seagard JL. Differential endocannabinoid regulation of baroreflex-evoked sympathoinhibition in normotensive versus hypertensive rats. Auton Neurosci 2009; 150:82-93. [PMID: 19464961 DOI: 10.1016/j.autneu.2009.05.243] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 04/29/2009] [Accepted: 05/06/2009] [Indexed: 11/16/2022]
Abstract
Previously, we found that endocannabinoids acting at cannabinoid 1 receptors in the nucleus tractus solitarius prolonged baroreflex inhibition of renal sympathetic nerve activity in normotensive Sprague Dawley rats. The current study investigated whether endocannabinoid signaling was altered in spontaneously hypertensive rats, a model marked by elevated sympathetic activity and depressed baroreflex responses. The effects of endocannabinoids in the nucleus tractus solitarius on baroreflex control of renal sympathetic nerve activity evoked by systemic pressor changes or by direct stimulation of nucleus tractus solitarius neurons, which produced depressor and sympathoinhibitory responses, were studied in Sprague Dawley rats, Wistar Kyoto rats, and spontaneously hypertensive rats. Evoked responses were compared before and after microinjection of AM404, which prolonged actions of endogenous endocannabinoids, or microinjection of an endocannabinoid, anandamide, into the baroreceptive region of the nucleus tractus solitarius. AM404 microinjections significantly prolonged evoked sympathoinhibition in Sprague Dawley and Wistar Kyoto rats, but had little effect in spontaneously hypertensive rats. Microinjections of anandamide prolonged sympathoinhibition in Sprague Dawley rats, with lesser effects in Wistar Kyoto rats and no effects in spontaneously hypertensive rats. Parallel studies found that density of binding sites of endocannabinoids in the nucleus tractus solitarius was significantly reduced in spontaneously hypertensive rats versus the normotensive rats. Results indicate that attenuated function of the endocannabinoid system in the nucleus tractus solitarius of spontaneously hypertensive rats resulted in less modulation of baroreflex-evoked sympathoinhibition and that reduced cannabinoid 1 receptor density could contribute to blunted baroreflex-induced sympathoinhibition and elevated sympathetic tone characteristic of spontaneously hypertensive rats.
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Affiliation(s)
- D T Brozoski
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
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18
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Carolina Takakura A, Santos Moreira T, Menani JV, Ribeiro Campos R, Colombari E. Commissural nucleus of the solitary tract is important for cardiovascular responses to caudal pressor area activation. Brain Res 2007; 1161:32-7. [PMID: 17604008 DOI: 10.1016/j.brainres.2007.05.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 05/22/2007] [Accepted: 05/27/2007] [Indexed: 02/07/2023]
Abstract
The nucleus of the solitary tract (NTS) is the site of the first synapse of cardiovascular afferent fibers in the central nervous system. Important mechanisms for cardiovascular regulation are also present in the caudal pressor area (CPA) localized at the caudal end of the ventrolateral medulla. In the present study we sought to investigate the role of the commissural subnucleus of the NTS (commNTS) on pressor and tachycardic responses induced by l-glutamate injected into the CPA. Male Holtzman rats (n=8 rats/group) anesthetized with urethane (1.2 g/kg of body weight, iv) received injections of the GABA(A) receptor agonist muscimol into the commNTS. Unilateral injection of L-glutamate (10 nmol/100 nL) into the CPA increased mean arterial pressure (MAP, 31+/-4 mm Hg, vs. saline: 3+/-2 mm Hg) and heart rate (HR, 44+/-8 bpm, vs. saline: 10 +/-7 bpm). Inhibition of commNTS neurons with muscimol (120 pmol/60 nL) abolished the increase in MAP (9+/-4 mm Hg) and HR (17+/-7 bpm) produced by l-glutamate into the CPA. The present results suggest that the pressor and tachycardic responses to CPA activation are dependent on commNTS mechanisms.
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Affiliation(s)
- Ana Carolina Takakura
- Department of Physiology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04023-060, São Paulo, SP, Brazil
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Schultz HD, Li YL, Ding Y. Arterial chemoreceptors and sympathetic nerve activity: implications for hypertension and heart failure. Hypertension 2007; 50:6-13. [PMID: 17502495 DOI: 10.1161/hypertensionaha.106.076083] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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Moreira TS, Sato MA, Takakura ACT, Menani JV, Colombari E. Role of pressor mechanisms from the NTS and CVLM in control of arterial pressure. Am J Physiol Regul Integr Comp Physiol 2005; 289:R1416-25. [PMID: 16051722 DOI: 10.1152/ajpregu.00053.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present study, we investigated the effects of inhibition of the caudal ventrolateral medulla (CVLM) with the GABA(A) agonist muscimol combined with the blockade of glutamatergic mechanism in the nucleus of the solitary tract (NTS) with kynurenic acid (kyn) on mean arterial pressure (MAP), heart rate (HR), and regional vascular resistances. In male Holtzman rats anesthetized intravenously with urethane/chloralose, bilateral injections of muscimol (120 pmol) into the CVLM or bilateral injections of kyn (2.7 nmol) into the NTS alone increased MAP to 186 +/- 11 and to 142 +/- 6 mmHg, respectively, vs. control: 105 +/- 4 mmHg; HR to 407 +/- 15 and to 412 +/- 18 beats per minute (bpm), respectively, vs. control: 352 +/- 12 bpm; and renal, mesenteric and hindquarter vascular resistances. However, in rats with the CVLM bilaterally blocked by muscimol, additional injections of kyn into the NTS reduced MAP to 88 +/- 5 mmHg and mesenteric and hindquarter vascular resistances below control baseline levels. Moreover, in rats with the glutamatergic mechanisms of the NTS blocked by bilateral injections of kyn, additional injections of muscimol into the CVLM also reduced MAP to 92 +/- 2 mmHg and mesenteric and hindquarter vascular resistances below control baseline levels. Simultaneous blockade of NTS and CVLM did not modify the increase in HR but also abolished the increase in renal vascular resistance produced by each treatment alone. The results suggest that important pressor mechanisms arise from the NTS and CVLM to control vascular resistance and arterial pressure under the conditions of the present study.
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Affiliation(s)
- Thiago Santos Moreira
- Department of Physiology, Universidade Federal de São Paulo--Escola Paulista de Medicina, Rua Botucatu, São Paulo, SP, Brazil
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Sato MA, Schoorlemmer GHM, Menani JV, Lopes OU, Colombari E. Recovery of high blood pressure after chronic lesions of the commissural NTS in SHR. Hypertension 2003; 42:713-8. [PMID: 12900428 DOI: 10.1161/01.hyp.0000086523.51029.ec] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute electrolytic lesions of the commissural nucleus of the solitary tract (commNTS) reduce blood pressure (BP) in SHR but not in normotensive Wistar-Kyoto and Wistar rats and abolish the pressor response to intravenous injection of potassium cyanide. We investigated the chronic effect of commNTS lesions on mean arterial pressure (MAP), and on baroreceptor and chemoreceptor reflex responses in SHR. The contribution of the sympathetic nervous system and the hormones vasopressin and angiotensin II to maintenance of BP in lesioned SHR was also investigated. MAP fell to normotensive levels the day after lesioning the commNTS but returned to the hypertensive level 9 days later. The reflex tachycardia evoked by sodium nitroprusside remained attenuated for 10 days after commNTS lesions but became enhanced 30 days after commNTS lesions. The pressor component of the chemoreflex elicited by potassium cyanide remained blocked for 30 days after lesions. Vasopressin antagonist or ACE blocker did not change MAP in sham or commNTS-lesioned SHR. Ganglionic blockade with hexamethonium elicited similar reductions in MAP in sham and commNTS-lesioned SHR. Results demonstrated that commNTS lesions in SHR produce a transient fall in BP and a long-lasting inhibition of the pressor response of the chemoreflex. Therefore, the blockade of the pressor response to peripheral chemoreflex activation is not sufficient to chronically reduce MAP in SHR. In the chronic absence of the commNTS, other subnuclei of the NTS or other brain stem nuclei may reorganize to replace the function of commNTS neurons, restoring sympathetic activity and high BP in SHR.
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Affiliation(s)
- Monica Akemi Sato
- Department of Physiology, Universidade Federal de Sao Paulo, Escola Paulista de Medicina, Sao Paulo, SP, Brazil
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