The bradycardic and hypotensive responses to serotonin are reduced by activation of GABA(A) receptors in the nucleus tractus solitarius of awake rats

The bradycardic and hypotensive responses to serotonin are reduced by activation of GABA(A) receptors in the nucleus tractus solitarius of awake rats

Autor Callera, Joao Carlos Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
De Luca, Laurival Antonio Google Scholar
Menani, Jose Vanderlei Google Scholar
Instituição UNESP
Universidade Federal de São Paulo (UNIFESP)
Resumo We investigated the effects of bilateral injections of the GABA receptor agonists muscimol (GABA(A)) and baclofen (GABA(B)) into the nucleus tractus solitarius (NTS) on the bradycardia and hypotension induced by iv serotonin injections (5-HT, 2 mu g/rat) in awake male Holtzman rats. 5-HT was injected in rats with stainless steel cannulas implanted bilaterally in the NTS, before and 5, 15, and 60 min after bilateral injections of muscimol or baclofen into the NTS. the responses to 5-HT were tested before and after the injection of atropine methyl bromide. Muscimol (50 pmol/50 nl, N = 8) into the NTS increased basal mean arterial pressure (MAP) from 115 4 to 144 6 mmHg, did not change basal heart rate (HR) and reduced the bradycardia (-40 +/- 14 and -73 +/- 26 bpm at 5 and 15 min, respectively, vs -180 +/- 20 bpm for the control) and hypotension (-11 +/- 4 and -14 +/- 4 mmHg, vs -40 +/- 9 mmHg for the control) elicited by 5-HT. Baclofen (12.5 pmol/50 nl, N = 7) into the NTS also increased basal MAP, but did not change basal HR, bradycardia or hypotension in response to 5-HT injections. Atropine methyl bromide (1 mg/kg body weight) injected iv reduced the bradycardic and hypotensive responses to 5-HT injections. the stimulation of GABAA receptors in the NTS of awake rats elicits a significant increase in basal MAP and decreases the cardiac Bezold-Jarisch reflex responses to iv 5-HT injections.
Palavra-chave muscimol
GABA receptors
nucleus tractus solitarius
parasympathetic component
Bezold-Jarisch reflex
awake rats
Idioma Inglês
Data de publicação 2005-07-01
Publicado em Brazilian Journal of Medical and Biological Research. São Paulo: Assoc Bras Divulg Cientifica, v. 38, n. 7, p. 1123-1131, 2005.
ISSN 0100-879X (Sherpa/Romeo, fator de impacto)
Publicador Assoc Bras Divulg Cientifica
Extensão 1123-1131
Fonte http://dx.doi.org/10.1590/S0100-879X2005000700016
Direito de acesso Acessso aberto Open Access
Tipo Artigo
Web of Science WOS:000230829900016
SciELO S0100-879X2005000700016 (estatísticas na SciELO)
Endereço permanente http://repositorio.unifesp.br/handle/11600/28383

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