INHIBITION OF THE CAUDAL PRESSOR AREA REDUCES CARDIORESPIRATORY CHEMOREFLEX RESPONSES

Autor(es)

Takakura, A. C. ^[1] ; Moreira, T. S. ^[2] ; Menani, J. V. ^[1] ; Colombari, E. ^[1]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Sch Dent, Dept Physiol & Pathol, BR-14801903 Araraquara, SP - Brazil

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Neuroscience; v. 177, p. 84-92, MAR 17 2011.
• Citações Web of Science: 2

Resumo

The caudal pressor area (CPA) is a brainstem area located close to the spinal cord. The activation of the CPA increases sympathetic activity and mean arterial pressure (MAP) by mechanisms dependent on the commissural nucleus of the solitary tract (commNTS) and rostroventrolateral medulla, however, the signals that activate the CPA to produce these responses are still unknown. Therefore, in the present study, we investigated the activity of glutamatergic and GABAergic mechanisms from the CPA and commNTS in rats exposed to hypoxia and the effects of the inhibition of CPA neurons on cardiorespiratory responses to peripheral chemoreceptor activation with i.v. sodium cyanide (NaCN). Male Sprague-Dawley rats (250-280 g, n=5-8/group) were used. In conscious rats, most of the commNTS neurons (66 +/- 11%) and part of the CPA neurons (36 +/- 7%) activated by hypoxia (8% O2) were glutamatergic (contained VGLUT2mRNA). Small part of the neurons activated during hypoxia was GABAergic (contained GAD-67mRNA) in the commNTS (9 +/- 4%) or the CPA (6 +/- 2%). In urethane anesthetized rats, the inhibition of CPA neurons with bilateral injections of muscimol (GABA-A agonist, 2 mM) reduced baseline MAP, splanchnic sympathetic nerve discharge (SND) and phrenic nerve discharge (PND). Muscimol into the CPA also reduced by around 50% the pressor and sympathoexcitatory responses and the increase in PND to peripheral chemoreceptor activation with NaCN (50 mu g/kg i.v.), without changing sympathetic baroreflex responses. These data suggest that CPA mechanisms facilitate cardiorespiratory responses to peripheral chemoreflex activation. Immunohistochemistry results also suggest that at least part of the CPA mechanisms activated by hypoxia is glutamatergic. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 04/08282-6 - Envolvimento dos nucleos do trato solitario (nts) nas respostas cardiovasculares produzidas pela estimulacao e inibicao da area pressora caudal (apc).
• Beneficiário: Ana Carolina Takakura Moreira
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• 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
• Processo FAPESP: 07/06430-6 - Mecanismos centrais envolvidos no controle cardiovascular e do equilíbrio hidroeletrolítico
• Beneficiário: José Vanderlei Menani
• Modalidade de apoio: Auxílio à Pesquisa - Regular