Important GABAergic mechanism within the NTS and the control of sympathetic baroreflex in SHR

Autor(es)

Moreira, Thiago S. ^[1] ; Takakura, Ana C. ^[2] ; Colombari, Eduardo ^{[2, 3, 4]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil

^[2] Sao Paulo State Univ UNESP, Sch Dent, Dept Physiol & Pathol, BR-14801903 Araraquara, SP - Brazil

^[3] Fed Univ Sao Paulo UNIFESP, Sch Med, Dept Physiol, BR-04023060 Sao Paulo - Brazil

^[4] ABC, Sch Med, Dept Physiol, BR-09060870 Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL; v. 159, n. 1-2, p. 62-70, JAN 20 2011.
• Citações Web of Science: 6

Resumo

Inhibitory neurotransmission has an important role in the processing of sensory afferent signals in the nucleus of the solitary tract (NTS), particularly in spontaneously hypertensive rats (SHR). In the present study, we tested the hypothesis that gamma-aminobutyric acid (GABA) mediated neurotransmission within the NTS produces an inhibition of the baroreflex response of splanchnic sympathetic nerve discharge (sSND). In urethane-anesthetized, artificially ventilated and vagotomized male SHR and Wistar Kyoto (WKY) rats we compared baroreflex-response curves evoked after bilateral injections into the NTS of the GABA-A antagonist bicuculline (25 pmol/50 nl) or the GABA-B antagonist CGP 35348 (5 nmol/50 nl). Baseline MAP in SHR was higher than the WKY rats (SHR: 153+/-5, vs. WKY: 112+/-6 mm Hg, p<0.05). Bilateral injection of bicuculline or CGP 35348 into the NTS induced a transient (5 min) reduction in MAP (Delta = -26+/-4 and -41+/-6 mm Hg, respectively vs. saline Delta = +4+/-3 mm Hg, p<0.05) and sSND (Delta = -21+/-13 and -78+/-7%, respectively vs. saline: Delta = +6+/-4% p<0.05). Analysis of the baroreceptor curve revealed a decrease in the lower plateau (43+/-11 and 15+/-5%, respectively vs. saline: 78+/-6%, p<0.05) and an increase in the sympathetic gain of baroreflex (6.3+/-0.3, 7.2+/-0.8% respectively vs. saline: 4.2+/-0.4%, p<0.05). Bicuculline or CGP35348 into the NTS in WKY rats did not change MAP, sSND and sympathetic baroreflex gain. These data indicate that GABAergic mechanisms within the NTS act tonically reducing sympathetic baroreflex gain in SHR. Crown Copyright (C) 2010 Published by Elsevier By. All rights reserved. (AU)

• Processo FAPESP: 08/57388-2 - Participação do núcleo retrotrapezoide na resposta ventilatória à hipercapnia em ratos não anestesiados
• Beneficiário: Ana Carolina Takakura Moreira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 06/60174-9 - Mecanismos neurais envolvidos na integração do quimioreflexo central e periférico
• Beneficiário: Thiago dos Santos Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores