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Tian L, Tang G, Liu Q, Yin Y, Li Y, Zhong Y. Blockade of adenosine A1 receptor in nucleus tractus solitarius attenuates baroreflex sensitivity response to dexmedetomidine in rats. Brain Res 2020; 1743:146949. [PMID: 32522627 DOI: 10.1016/j.brainres.2020.146949] [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: 02/11/2020] [Revised: 05/07/2020] [Accepted: 06/04/2020] [Indexed: 12/30/2022]
Abstract
The α2-adrenergic receptor (α2-AR) agonist dexmedetomidine increases baroreflex sensitivity (BRS). In the current study, we examined the potential role of adenosine A1 receptor (A1R) within the nucleus tractus solitaries (NTS) in such a response. Briefly, adult male Sprague-Dawley rats were anesthetized and randomly received microinjection of selective A1R antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.1 pmol/1 μl) or saline vehicle into the right NTS. Ten min after the microinjection, dexmedetomidine infusion started at a rate of 30 μg/kg over 15 min followed by infusion at 15 μg·kg-1·h-1 for 105 min, or 100 μg/kg over 15 min followed by infusion at 50 μg·kg-1·h-1 for 105 min. BRS was examined using a standard phenylephrine method prior to infusion (T0), 60 min (T1) and 120 min (T2) after dexmedetomidine infusion started. Adenosine concentration in plasma and brainstem was measured with high-performance liquid chromatography with vs. without α2-AR antagonist atipamezole pretreatment (0.5 mg/kg, i.p.). Dexmedetomidine increased BRS at both 30 (T0: 0.55 ± 0.25 vs. T1: 2.45 ± 0.37, T2: 2.26 ± 0.56 ms/mmHg, P < 0.05) and 100 μg/kg (T0: 0.63 ± 0.24 vs. T1: 6.21 ± 1.87, T2: 6.30 ± 2.12 ms/mmHg, P < 0.05). DPCPX pretreatment obliterated BRS response to 100-μg/kg dexmedetomidine. At 100 μg/kg, dexmedetomidine increased adenosine concentration in plasma (0.23 ± 0.11 to 0.45 ± 0.07 μg/ml, P < 0.05) and brainstem (1.46 ± 0.30 to 2.52 ± 0.22 μg/ml, P < 0.05); such effect was blocked by atipamezole pretreatment. Western blot analysis showed α2-AR up-regulation by 100-μg/kg dexmedetomidine, which can be prevented by DPCPX. Double-labeling with glial fibrillary acidic protein showed α2-AR up-regulation in astrocytes in the NTS. These results suggest that dexmedetomidine enhances baroreflex sensitivity, possibly by increasing adenosine in NTS and α2-AR expression in astrocytes.
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Affiliation(s)
- Lei Tian
- Department of Anesthesiology, Zigong First People's Hospital, Zigong, Sichuan, China
| | - Guoqiang Tang
- Department of Anesthesiology, Zigong First People's Hospital, Zigong, Sichuan, China
| | - Qian Liu
- Department of Anesthesiology, Zigong First People's Hospital, Zigong, Sichuan, China
| | - Yongqiang Yin
- Department of Anesthesiology, Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Yiping Li
- Department of Anesthesiology, Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Yi Zhong
- Department of Anesthesiology, Affiliated Hospital of Guizhou Medical University, Guiyang, China.
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Onishi M, Yamanaka K, Miyamoto Y, Waki H, Gouraud S. Trpv4 involvement in the sex differences in blood pressure regulation in spontaneously hypertensive rats. Physiol Genomics 2018; 50:272-286. [PMID: 29373075 DOI: 10.1152/physiolgenomics.00096.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Arterial pressure (AP) is lower in premenopausal women than in men of a similar age. Premenopausal women exhibit a lower sympathetic activity and a greater baroreceptor reflex; however, mechanisms controlling sex differences in blood pressure regulation are not well understood. We hypothesized that different neuronal functions in the cardiovascular centers of the brains of men and women may contribute to the sex difference in cardiovascular homeostasis. Our previous studies on male spontaneously hypertensive rats (SHRs) and their normotensive counterparts, Wistar Kyoto (WKY) rats, revealed that the gene-expression profile of the nucleus tractus solitarius (NTS), a region of the medulla oblongata that is pivotal for regulating the set point of AP, is strongly associated with AP. Thus, we hypothesized that gene-expression profiles in the rat NTS are related to sex differences in AP regulation. Because female SHRs clearly exhibit lower AP than their male counterparts of a similar age, we investigated whether SHR NTS exhibits sex differences in gene expression by using microarray and RT-qPCR experiments. The transcript for transient receptor potential cation channel subfamily V member 4 ( Trpv4) was found to be upregulated in SHR NTS in females compared with that in males. The channel was expressed in neurons and glial cells within NTS. The TRPV4 agonist 4-alpha-phorbol-12,13-didecanoate (4α-PDD) decreased blood pressure when injected into NTS of rats. These findings suggest that altered TRPV4 expression might be involved in the sex differences in blood pressure regulation.
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Affiliation(s)
- Makiko Onishi
- Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan.,Institute for Human Life Innovation, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan
| | - Ko Yamanaka
- Department of Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai-city, Chiba , Japan
| | - Yasunori Miyamoto
- Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan.,Program for Leading Graduate Schools, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan.,Institute for Human Life Innovation, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan
| | - Hidefumi Waki
- Department of Physiology, Graduate School of Health and Sports Science, Juntendo University, Inzai-city, Chiba , Japan
| | - Sabine Gouraud
- Program for Leading Graduate Schools, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan.,Department of Biology, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo , Japan
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Effect of Noradrenergic Neurotoxin DSP-4 and Maprotiline on Heart Rate Spectral Components in Stressed and Resting Rats. Bull Exp Biol Med 2017; 163:302-306. [PMID: 28744642 DOI: 10.1007/s10517-017-3790-2] [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: 09/22/2016] [Indexed: 10/19/2022]
Abstract
The effects of intraperitoneal DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a noradrenergic neurotoxin) and maprotiline (an inhibitor of norepinephrine reuptake in synapses) on spectral components of heart rhythm variability were examined in outbred male and female rats treated with these agents in daily doses of 10 mg/kg for 3 days. At rest, DSP-4 elevated LF and VLF spectral components in male and female rats. Maprotiline elevated LF and VLF components in males at rest, increased HR and reduced all spectral components in resting females. Stress against the background of DSP-4 treatment sharply increased heart rate and reduced the powers of all spectral components (especially LF and VLF components). In maprotiline-treated rats, stress increased the powers of LF and VLF components. Thus, the central noradrenergic system participates in the formation of LF and VLF spectral components of heart rate variability at rest and especially during stressful stimulation, which can determine the phasic character of changes in the heart rate variability observed in stressed organism.
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Gouraud SS, Takagishi M, Kohsaka A, Maeda M, Waki H. Altered neurotrophic factors' expression profiles in the nucleus of the solitary tract of spontaneously hypertensive rats. Acta Physiol (Oxf) 2016; 216:346-57. [PMID: 26485190 DOI: 10.1111/apha.12618] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 05/19/2015] [Accepted: 10/10/2015] [Indexed: 01/09/2023]
Abstract
AIM Our previous findings suggest that the nucleus of the solitary tract (NTS), a pivotal region for regulating the set point of arterial pressure, exhibits abnormal inflammation in pre-hypertensive and spontaneously hypertensive rats (SHRs), with elevated anti-apoptotic and low apoptotic factor levels compared with that of normotensive Wistar-Kyoto (WKY) rats. Whether this chronic condition affects neuronal growth and plasticity in the NTS remains unknown. To unveil the characteristics of the neurodevelopmental environment in the NTS of SHRs, we investigated the expression of neurotrophic factors transcripts in SHRs. METHODS RT(2) Profiler PCR Array targeting rat neurotrophins and their receptors was used to screen for differentially expressed transcripts in the NTS of SHRs compared to that of WKY rats. Protein expression and physiological functions of some of the differentially expressed transcripts were also studied. RESULTS Gene and protein expressions of glial cell line-derived neurotrophic factor family receptor alpha-3 (Gfrα-3) factor were both upregulated in the NTS of adult SHRs. Gene expressions of corticotropin-releasing hormone-binding protein (Crhbp), interleukin-10 receptor alpha (Il-10ra) and hypocretin (Hcrt) were downregulated in the NTS of adult SHRs. The Gfrα-3 transcript was increased and the Hcrt transcript was decreased in the NTS of young pre-hypertensive SHRs, suggesting that these profiles are not secondary to hypertension. Moreover, microinjection in the NTS of hypocretin-1 decreased blood pressure in adult SHRs. CONCLUSION These results suggest that altered neurotrophic factors transcript profiles may affect the normal development and function of neuronal circuitry that regulates cardiovascular autonomic activity, thereby resulting in manifestations of neurogenic hypertension in SHRs.
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Affiliation(s)
- S. S. Gouraud
- Department of Biology; Faculty of Science; Ochanomizu University; Tokyo Japan
| | - M. Takagishi
- Department of Physiology; Wakayama Medical University; Wakayama Japan
| | - A. Kohsaka
- Department of Physiology; Wakayama Medical University; Wakayama Japan
| | - M. Maeda
- Department of Physiology; Wakayama Medical University; Wakayama Japan
| | - H. Waki
- Graduate School of Sport and Health Science; Juntendo University; Chiba Japan
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Sun GC, Ho WY, Chen BR, Cheng PW, Cheng WH, Hsu MC, Yeh TC, Hsiao M, Lu PJ, Tseng CJ. GPCR dimerization in brainstem nuclei contributes to the development of hypertension. Br J Pharmacol 2015; 172:2507-18. [PMID: 25573074 PMCID: PMC4409903 DOI: 10.1111/bph.13074] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/20/2014] [Accepted: 12/29/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE μ-Opioid receptors, pro-opiomelanocortin and pro-enkephalin are highly expressed in the nucleus tractus solitarii (NTS) and μ receptor agonists given to the NTS dose-dependently increased BP. However, the molecular mechanisms of this process remain unclear. In vitro, μ receptors heterodimerize with α2A -adrenoceptors. We hypothesized that α2A -adrenoceptor agonists would lose their depressor effects when their receptors heterodimerize in the NTS with μ receptors. EXPERIMENTAL APPROACH We microinjected μ-opioid agonists and antagonists into the NTS of rats and measured changes in BP. Formation of μ receptor/α2A -adrenoceptor heterodimers was assessed with immunofluorescence and co-immunoprecipitation methods, along with proximity ligation assays. KEY RESULTS Immunofluorescence staining revealed colocalization of α2A -adrenoceptors and μ receptors in NTS neurons. Co-immunoprecipitation revealed interactions between α2A -adrenoceptors and μ receptors. In situ proximity ligation assays confirmed the presence of μ receptor/α2A -adrenoceptor heterodimers in the NTS. Higher levels of endogenous endomorphin-1 and μ receptor/α2A -adrenoceptor heterodimers were found in the NTS of hypertensive rats, than in normotensive rats. Microinjection of the μ receptor agonist [D-Ala(2) , MePhe(4) , Gly(5) -ol]-enkephalin (DAMGO), but not that of the α2A -adrenoceptor agonist guanfacine, into the NTS of normotensive rats increased μ receptor/α2A -adrenoceptor heterodimer formation and BP elevation. The NO-dependent BP-lowering effect of α2A -adrenoceptor agonists was blunted following increased formation of μ receptor/α2A -adrenoceptor heterodimers in the NTS of hypertensive rats and DAMGO-treated normotensive rats. CONCLUSIONS AND IMPLICATIONS Increases in endogenous μ receptor agonists in the NTS induced μ receptor/α2A -adrenoceptor heterodimer formation and reduced the NO-dependent depressor effect of α2A -adrenoceptor agonists. This process could contribute to the pathogenesis of hypertension.
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MESH Headings
- Adrenergic alpha-2 Receptor Agonists/administration & dosage
- Adrenergic alpha-2 Receptor Agonists/pharmacology
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/pharmacology
- Animals
- Blood Pressure/drug effects
- Brain Stem/drug effects
- Brain Stem/metabolism
- Dimerization
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/administration & dosage
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Hypertension/chemically induced
- Hypertension/metabolism
- Male
- Microinjections
- Narcotic Antagonists/administration & dosage
- Narcotic Antagonists/pharmacology
- Oligopeptides/metabolism
- Protein Multimerization
- Rats
- Rats, Inbred SHR
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Solitary Nucleus/drug effects
- Solitary Nucleus/metabolism
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Affiliation(s)
- Gwo-Ching Sun
- Institute of Clinical Medicine, National Cheng-Kung UniversityTainan, Taiwan
- Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung Medical UniversityKaohsiung, Taiwan
- Department of Medical Education and Research, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
| | - Wen-Yu Ho
- Division of General Internal Medicine, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical UniversityKaohsiung, Taiwan
- Department of Internal Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical UniversityKaohsiung, Taiwan
- Department of Pharmacology, National Defense Medical CenterTaipei, Taiwan
| | - Bo-Rung Chen
- Department of Medical Education and Research, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
| | - Pei-Wen Cheng
- Department of Medical Education and Research, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
- Department of Pharmacology, National Defense Medical CenterTaipei, Taiwan
| | - Wen-Han Cheng
- Department of Medical Education and Research, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
- Institute of Clinical Medicine, National Yang-Ming UniversityTaipei, Taiwan
| | - Mei-Chi Hsu
- Department of Nursing, I-Shou UniversityKaohsiung, Taiwan
| | - Tung-Chen Yeh
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
| | - Michael Hsiao
- Genomics Research Center, Academia SinicaTaipei, Taiwan
| | - Pei-Jung Lu
- Institute of Clinical Medicine, National Cheng-Kung UniversityTainan, Taiwan
| | - Ching-Jiunn Tseng
- Department of Medical Education and Research, Kaohsiung Veterans General HospitalKaohsiung, Taiwan
- Department of Pharmacology, National Defense Medical CenterTaipei, Taiwan
- Institute of Clinical Medicine, National Yang-Ming UniversityTaipei, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical UniversityTaichung, Taiwan
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Santiago FE, Fior-Chadi DR, Carrettiero DC. Alpha2-adrenoceptor and adenosine A1 receptor within the nucleus tractus solitarii in hypertension development. Auton Neurosci 2014; 187:36-44. [PMID: 25466830 DOI: 10.1016/j.autneu.2014.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/21/2014] [Accepted: 11/01/2014] [Indexed: 02/07/2023]
Abstract
Alpha2-adrenoceptor and A1 adenosine receptor systems within the nucleus tractus solitarii (NTS) play an important role in cardiovascular control. Deregulation of these systems may result in an elevated sympathetic tone, one of the root causes of neurogenic hypertension. The dorsomedial/dorsolateral and subpostremal NTS subnuclei of spontaneously hypertensive rats (SHR) show density changes in both receptors, even at 15 days of age, prior to the onset of hypertension. In addition, adenosine A1 receptors have been specifically reported to modulate alpha2-adrenoceptors in several brain regions, including the NTS, via a PLC-dependent pathway involving cross regulation between sympathetic neurons and astrocytes. The physiological cross talk between these receptor systems is also deregulated in SHR suggesting that alpha2-adrenoceptor and A1 adenosine receptor might be germane to the development of hypertension. In this review, we will focus on these systems within the NTS during development, pointing out some interesting modulations in processes, and chemical changes within specific subnuclei of NTS circuitry, that might have implications for neurogenic hypertension.
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Affiliation(s)
- Fernando E Santiago
- Universidade Federal do ABC (UFABC), Centro de Ciências Naturais e Humanas, Santo André, SP, Brazil
| | - Débora R Fior-Chadi
- Universidade de São Paulo (USP), Departamento de Fisiologia, Instituto de Biociências, São Paulo, SP, Brazil
| | - Daniel C Carrettiero
- Universidade Federal do ABC (UFABC), Centro de Ciências Naturais e Humanas, Santo André, SP, Brazil.
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Cinelli E, Bongianni F, Pantaleo T, Mutolo D. Suppression of the cough reflex by α 2-adrenergic receptor agonists in the rabbit. Physiol Rep 2013; 1:e00122. [PMID: 24400133 PMCID: PMC3871446 DOI: 10.1002/phy2.122] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/16/2013] [Accepted: 09/18/2013] [Indexed: 01/26/2023] Open
Abstract
The α2-adrenergic receptor agonist clonidine has been shown to inhibit citric acid-induced cough responses in guinea pigs when administered by aerosol, but not orally. In contrast, oral or inhaled clonidine had no effect on capsaicin-induced cough and reflex bronchoconstriction in humans. In addition, intravenous administration of clonidine has been shown to depress fentanyl-induced cough in humans. We investigated the effects of the α2-adrenergic receptor agonists, clonidine and tizanidine, on cough responses induced by mechanical and chemical (citric acid) stimulation of the tracheobronchial tree. Drugs were microinjected (30–50 nL) into the caudal nucleus tractus solitarii (cNTS) and the caudal ventral respiratory group (cVRG) as well as administered intravenously in pentobarbital sodium-anesthetized, spontaneously breathing rabbits. Bilateral microinjections of clonidine into the cNTS or the cVRG reduced cough responses at 0.5 mmol/L and abolished the cough reflex at 5 mmol/L. Bilateral microinjections of 0.5 mmol/L tizanidine into the cNTS completely suppressed cough responses, whereas bilateral microinjections of 5 mmol/L into the cVRG only caused mild reductions in them. Depressant effects on the cough reflex of clonidine and tizanidine were completely reverted by microinjections of 10 mmol/L yohimbine. Intravenous administration of clonidine (80–120 μg/kg) or tizanidine (150–300 μg/kg) strongly reduced or completely suppressed cough responses. These effects were reverted by intravenous administration of yohimbine (300 μg/kg). The results demonstrate that activation of α2-adrenergic receptors in the rabbit exerts potent inhibitory effects on the central mechanism generating the cough motor pattern with a clear action at the level of the cNTS and the cVRG.
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Affiliation(s)
- Elenia Cinelli
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università degli Studi di Firenze Viale G.B. Morgagni 63, 50134, Firenze, Italy
| | - Fulvia Bongianni
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università degli Studi di Firenze Viale G.B. Morgagni 63, 50134, Firenze, Italy
| | - Tito Pantaleo
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università degli Studi di Firenze Viale G.B. Morgagni 63, 50134, Firenze, Italy
| | - Donatella Mutolo
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università degli Studi di Firenze Viale G.B. Morgagni 63, 50134, Firenze, Italy
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Kawada T, Akiyama T, Shimizu S, Kamiya A, Uemura K, Turner MJ, Shirai M, Sugimachi M. Sympathetic afferent stimulation inhibits central vagal activation induced by intravenous medetomidine in rats. Acta Physiol (Oxf) 2013; 209:55-61. [PMID: 23710753 DOI: 10.1111/apha.12123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/08/2013] [Accepted: 05/21/2013] [Indexed: 11/29/2022]
Abstract
AIM To examine whether sympathetic afferent stimulation (SAS) inhibits central vagal activation induced by α2 -adrenergic stimulation. METHODS In anaesthetized Wistar-Kyoto rats, a cardiac microdialysis technique was applied to the left ventricle, and the effect of α2 -adrenergic stimulation by medetomidine on myocardial interstitial acetylcholine (ACh) levels was examined in the absence (n = 6) or the presence (n = 6) of SAS delivered from the left stellate ganglion. The effect of electrical vagal efferent stimulation on myocardial interstitial ACh release was also examined in the absence or the presence of SAS (n = 6). RESULTS Intravenous medetomidine (0.1 mg kg(-1) ) significantly increased myocardial interstitial ACh levels in the absence of SAS (from 1.95 ± 0.79 to 3.36 ± 1.61 nM, P < 0.05), but not in the presence of SAS (from 1.67 ± 0.67 to 2.01 ± 0.78 nM). In contrast, electrical vagal nerve stimulation increased myocardial interstitial ACh level to the same degree regardless of SAS (from 1.66 ± 0.16 to 3.93 ± 0.72 nM without SAS vs. 4.05 ± 0.89 nM with SAS). CONCLUSION Sympathetic afferent stimulation inhibited medetomidine-induced ACh release, but not electrical stimulation-induced ACh release, suggesting that SAS inhibited medetomidine-induced vagal activation via central mechanisms. While central vagal activation by α2 -adrenergic agonists could be an alternative to electrical vagal activation, blocking sympathetic afferent input may be important to increase the efficacy of α2 -adrenergic agonists in enhancing vagal nerve activity.
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Affiliation(s)
- T. Kawada
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - T. Akiyama
- Department of Cardiac Physiology; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - S. Shimizu
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - A. Kamiya
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - K. Uemura
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - M. J. Turner
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - M. Shirai
- Department of Cardiac Physiology; National Cerebral and Cardiovascular Center; Osaka; Japan
| | - M. Sugimachi
- Department of Cardiovascular Dynamics; National Cerebral and Cardiovascular Center; Osaka; Japan
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Carrettiero DC, Ferrari MF, Fior-Chadi DR. Alpha2-adrenergic receptor distribution and density within the nucleus tractus solitarii of normotensive and hypertensive rats during development. Auton Neurosci 2012; 166:39-46. [DOI: 10.1016/j.autneu.2011.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 09/29/2011] [Accepted: 10/01/2011] [Indexed: 02/07/2023]
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α1-adrenergic receptors facilitate inhibitory neurotransmission to cardiac vagal neurons in the nucleus ambiguus. Neuroscience 2011; 193:154-61. [PMID: 21771639 DOI: 10.1016/j.neuroscience.2011.07.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 06/29/2011] [Accepted: 07/11/2011] [Indexed: 11/22/2022]
Abstract
The cholinergic cardiac vagal neurons (CVNs), located in the nucleus ambiguus, are the origin of cardioinhibitory parasympathetic activity. Catecholaminergic neurons in nearby regions of the brainstem, including the C1 and C2 cell groups, are thought to play a key role in both arousing from sleep and maintaining wakefulness. Because norepinephrine (NE) could play an important role in influencing the activity of CVNs, particularly in response to sleeping/waking and arousal states, the present study investigated the contribution of α(1)-adrenergic receptor activation to augment inhibitory and/or blunt excitatory neurotransmission to CVNs. To test the effects of α(1)-adrenergic receptor activation, CVNs were labeled in rats by retrograde tracing and synaptic events were recorded by whole cell voltage clamp techniques in vitro. Prazosin, an inverse agonist of α(1)-adrenergic receptor, significantly decreased the frequency of both GABAergic and glycinergic neurotransmission to CVNs. Activation of α(1)-adrenergic receptors by the α(1)-adrenergic receptor agonists NE or phenylephrine (PE) both significantly increased GABAergic and glycinergic inhibitory event frequency. This effect was prevented by the sodium channel blocker tetrodotoxin (TTX). Activation of α(1)-adrenergic receptors did not alter glutamatergic neurotransmission to CVNs. This study indicates that α(1)-adrenergic receptor activation in the brainstem can facilitate inhibitory GABAergic and glycinergic neurotransmission so as to reduce CVN activity; this synaptic modulation may play a role in the tachycardia seen during NE-dependent behavioral arousal.
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Down-regulation of chemokine Ccl5 gene expression in the NTS of SHR may be pro-hypertensive. J Hypertens 2011; 29:732-40. [PMID: 21358418 DOI: 10.1097/hjh.0b013e328344224d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVES Recent studies have demonstrated that pro-inflammatory molecules such as junctional adhesion molecules-1 are highly expressed in the nucleus tractus solitarii (NTS) of the spontaneously hypertensive rat (SHR), compared to normotensive rats (Wistar-Kyoto rats: WKY), suggesting that the NTS of SHR may exhibit an abnormal inflammatory state. In the present study, we tested whether gene expression of inflammatory markers such as cytokines and chemokines is altered in the NTS of SHR and whether this contributes to the hypertensive phenotype in the SHR. METHODS We have performed RT Profiler PCR arrays in the NTS of SHR and WKY, which were designed to specifically target major cytokines/chemokines and their receptors. To validate PCR array results quantitative RT-PCR was performed. Microinjection studies using anesthetized rats were also carried out to examine whether validated inflammatory molecules exhibit functional roles on cardiovascular regulation at the level of the NTS. RESULTS Five inter-related transcripts were identified to be differentially expressed between the NTS of SHR and WKY. They include chemokine (C-C motif) ligand 5 (Ccl5), and its receptors, chemokine (C-C motif) receptor 1 and 3. All of them were down-regulated in the NTS of SHR compared to WKY. Moreover, we found that the protein Ccl5 microinjected into the NTS significantly decreased baseline arterial pressure and that the response was greater in the SHR compared to the WKY (-33.2±3.2 vs. -8.8±1.6 mmHg, P<0.001), demonstrating that its down-regulation in the NTS may contribute to hypertension in the SHR. CONCLUSION We suggest that gene expression of specific chemokines may be down-regulated to protect further inflammatory reactions in the NTS of SHR at the expense of arterial hypertension.
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Gouraud SS, Waki H, Bhuiyan ME, Takagishi M, Kohsaka A, Maeda M. Increased anti-apoptotic conditions in the nucleus tractus solitarii of spontaneously hypertensive rat. Auton Neurosci 2011; 162:15-23. [DOI: 10.1016/j.autneu.2011.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 01/14/2011] [Accepted: 01/20/2011] [Indexed: 10/18/2022]
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Bhuiyan ME, Waki H, Gouraud SS, Takagishi M, Kohsaka A, Maeda M. Histamine receptor H1 in the nucleus tractus solitarii regulates arterial pressure and heart rate in rats. Am J Physiol Heart Circ Physiol 2011; 301:H523-9. [PMID: 21622829 DOI: 10.1152/ajpheart.00263.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Axons of histamine (HA)-containing neurons are known to project from the posterior hypothalamus to many areas of the brain, including the nucleus tractus solitarii (NTS), a central brain structure that plays an important role in regulating arterial pressure. However, the functional significance of NTS HA is still not fully established. In this study, we microinjected HA or 2-pyridylethylamine, a HA-receptor H(1)-specific agonist, into the NTS of urethane-anesthetized Wister rats to identify the potential functions of NTS HA on cardiovascular regulation. When HA or H(1)-receptor-specific agonist was bilaterally microinjected into the NTS, mean arterial pressure (MAP) and heart rate (HR) were significantly increased, whereas pretreatment with the H(1)-receptor-specific antagonist cetirizine into the NTS significantly inhibited the cardiovascular responses. The maximal responses of MAP and HR changes induced by HA or H(1)-receptor-specific agonist were dose dependent. We also confirmed gene expression of HA receptors in the NTS and that the expression level of H(1) mRNA was higher than that of the other subtypes. In addition, we found that H(1) receptors are mainly expressed in neurons of the NTS. These findings suggested that HA within the NTS may play a role in regulating cardiovascular homeostasis via activation of H(1) receptors expressed in the NTS neurons.
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Affiliation(s)
- Mohammad E Bhuiyan
- Department of Physiology, Wakayama Medical University School of Medicine, Wakayama, Japan
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15
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Takagishi M, Waki H, Bhuiyan MER, Gouraud SS, Kohsaka A, Cui H, Yamazaki T, Paton JFR, Maeda M. IL-6 microinjected in the nucleus tractus solitarii attenuates cardiac baroreceptor reflex function in rats. Am J Physiol Regul Integr Comp Physiol 2009; 298:R183-90. [PMID: 19907006 DOI: 10.1152/ajpregu.00176.2009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent gene array and molecular studies have suggested that an abnormal gene expression profile of interleukin-6 (IL-6) in the nucleus tractus solitarii (NTS), a pivotal region for regulating arterial pressure, may be related to the development of neurogenic hypertension. However, the precise functional role of IL-6 in the NTS remains unknown. In the present study, we have tested whether IL-6 affects cardiovascular control at the level of the NTS. IL-6 (1, 10, and 100 fmol) was microinjected in the NTS of Wistar rats (280-350 g) under urethane anesthesia. Although the baseline levels of arterial pressure and heart rate did not change following IL-6 injections, the cardiac baroreflex in response to increased arterial pressure was dose-dependently attenuated. In addition, IL-6 (100 fmol) microinjections also attenuated l-glutamate-induced bradycardia at the level of the NTS. Immunohistochemical detection of IL-6 in naïve rats demonstrated that it was predominantly observed in neurons within the brain stem, including the NTS. These findings suggest that IL-6 within the NTS may play an important role for regulating cardiovascular control via modulation of input signals from baroreceptor afferents. Whether the abnormal gene expression of IL-6 in the NTS is associated in a causal way with hypertension remains to be resolved.
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Affiliation(s)
- Miwa Takagishi
- Department of Physiology, Wakayama Medical University School of Medicine, Wakayama, Japan
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16
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Yao ST. Alpha-adrenergic receptors in the nucleus tractus solitarii: fitting a new piece to a complex puzzle. Exp Physiol 2009; 94:771-2. [PMID: 19535613 DOI: 10.1113/expphysiol.2009.048009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Song T Yao
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Bristol Heart Institute, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK.
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