Cardiovascular responses evoked by activation or blockade of GABA(A) receptors in the hypothalamic PVN are attenuated in transgenic rats with low brain angiotensinogen

Item Type:	Article
Title:	Cardiovascular responses evoked by activation or blockade of GABA(A) receptors in the hypothalamic PVN are attenuated in transgenic rats with low brain angiotensinogen
Creators Name:	Gomes da Silva, A.Q. and Xavier, C.H. and Campagnole-Santos, M.J. and Caligiorne, S.M. and Baltatu, O.C. and Bader, M. and Santos, R.A. and Fontes, M.A.
Abstract:	Previous evidence indicates that a balance between inhibitory gabaergic and excitatory angiotensinergic factors in the PVN is important for cardiovascular control. We investigated the cardiovascular response evoked from activation or blockade of GABA(A) receptors in the paraventricular nucleus (PVN), in transgenic rats with low brain angiotensinogen [TGR(ASrAOGEN)]. Brain Ang II and Ang-(1-7) levels were also determined. In functional experiments, TGR(ASrAOGEN) and Sprague-Dawley rats (SD, control) were anesthetized with urethane and blood pressure (BP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded. Brain Ang II and Ang-(1-7) levels were largely reduced in TGR(ASrAOGEN) compared with SD rats. Inhibition of PVN neurons with the GABA(A) agonist, muscimol (1nmol/100nL), resulted in an attenuated fall in all cardiovascular variables in TGR(ASrAOGEN) compared with SD rats. This difference was particularly pronounced in HR (TGR Mus -23±6bpm vs. -77±9bpm SD Mus; P<0.05) and RSNA (TGR -3±10% vs.-29±8% SD; P<0.05). Furthermore, the sympathetic response evoked by blockade of GABA(A) receptors in the PVN of TGR(ASrAOGEN) was also largely suppressed. The present data indicate that the sympathetic outflow mediated by PVN neurons under basal conditions is suppressed in TGR(ASrAOGEN) rats corroborating the functional significance of brain angiotensin production in the central regulation of sympathetic output to the cardiovascular system.
Keywords:	Brain Renin-Angiotensin System, Sympathetic Tone, Paraventricular Nucleus, Transgenic Rat, Animals, Rats
Source:	Brain Research
ISSN:	0006-8993
Publisher:	Elsevier
Volume:	1448
Page Range:	101-110
Date:	11 April 2012
Official Publication:	https://doi.org/10.1016/j.brainres.2012.02.021
PubMed:	View item in PubMed

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