Exercise training normalizes an increased neuronal excitability of NTS-projecting neurons of the hypothalamic paraventricular nucleus in hypertensive rats

Autor(es)

Stern, Javier E. ^[1] ; Sonner, Patrick M. ^[1] ; Son, Sook Jin ^[1] ; Silva, Fabiana C. P. ^{[2, 1]} ; Jackson, Keshia ^[1] ; Michelini, Lisete C. ^[2]

Afiliação do(s) autor(es)

^[1] Georgia Hlth Sci Univ, Dept Physiol, Augusta, GA 30912 - USA

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Neurophysiology; v. 107, n. 10, p. 2912-2921, MAY 2012.
• Citações Web of Science: 14

Resumo

Stern JE, Sonner PM, Son SJ, Silva FC, Jackson K, Michelini LC. Exercise training normalizes an increased neuronal excitability of NTS-projecting neurons of the hypothalamic paraventricular nucleus in hypertensive rats. J Neurophysiol 107: 2912-2921, 2012. First published February 22, 2012; doi:10.1152/jn.00884.2011.-Elevated sympathetic outflow and altered autonomic reflexes, including impaired baroreflex function, are common findings observed in hypertensive disorders. Although a growing body of evidence supports a contribution of preautonomic neurons in the hypothalamic paraventricular nucleus (PVN) to altered autonomic control during hypertension, the precise underlying mechanisms remain unknown. Here, we aimed to determine whether the intrinsic excitability and repetitive firing properties of preautonomic PVN neurons that innervate the nucleus tractus solitarii (PVN-NTS neurons) were altered in spontaneously hypertensive rats (SHR). Moreover, given that exercise training is known to improve and/or correct autonomic deficits in hypertensive conditions, we evaluated whether exercise is an efficient behavioral approach to correct altered neuronal excitability in hypertensive rats. Patch-clamp recordings were obtained from retrogradely labeled PVN-NTS neurons in hypothalamic slices obtained from sedentary (S) and trained (T) Wistar-Kyoto (WKY) and SHR rats. Our results indicate an increased excitability of PVN-NTS neurons in SHR-S rats, reflected by an enhanced input-output function in response to depolarizing stimuli, a hyperpolarizing shift in Na+ spike threshold, and smaller hyperpolarizing afterpotentials. Importantly, we found exercise training in SHR rats to restore all these parameters back to those levels observed in WKY-S rats. In several cases, exercise evoked opposing effects in WKY-S rats compared with SHR-S rats, suggesting that exercise effects on PVN-NTS neurons are state dependent. Taken together, our results suggest that elevated preautonomic PVN-NTS neuronal excitability may contribute to altered autonomic control in SHR rats and that exercise training efficiently corrects these abnormalities. (AU)

• Processo FAPESP: 06/50548-9 - Efeitos do treinamento fisico sobre vias centrais de modulacao autonomica do controle cardiovascular: estudos comparativos na normotensao e hipertensao e efeitos da desnervacao sino-aortica.
• Beneficiário: Lisete Compagno Michelini
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 02/11937-9 - Efeitos beneficos do treinamento fisico sobre o sistema cardiovascular de hipertensos: adaptacoes perifericas e centrais.
• Beneficiário: Lisete Compagno Michelini
• Modalidade de apoio: Auxílio à Pesquisa - Regular