Papel da leptina e insulina na via PI 3-quinase/Akt em hipotalamo de ratos submetidos a exercicio fisico / Exercise improves insulin and leptin sensitivity in hypothalamus of wistar rats

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Prolonged exercise of medium to high intensity is known to profoundly affect energy balance in rats. In male rats, in particular, moderately to severely intense programs lead to a reduction in food intake that contributes to retard deposition of energy as both fat and protein constituents. However the exact causes for the appetite-supressive effects of exercise are not known. Recently we and others have demonstrated that insulin and leptin have their anorectic-induced effect mediated by the PI 3-ldnase pathway. In the present study we determined whether exercise alters the expression and/or activity of proteins involved in insulin-signal transduction in hypothalamus after leptin or insulin stimulus. Male Wistar rats swam 6h/day for one day. Then, animals were treated with or without intracerebroventricular (i.c.v) insulin or leptin immediately after the exercise bout. lev. insulin or leptin infusion reduced food intake in exercised rats to a greater extent than that observed in sedentary rats. Insulin or leptin-stimulated phosphorylation of IRS-1/2, the associations of PI 3~kinase to IRS-1/2 and phosphorylation of Akt in hypothalamus were decreased in sedentary rats compared to exercised rats, interestingly basal serine phosphorylation of Akt was higher in the exercised rats. The present study provides direct measurements of insulin signaling in hypothalamus, and documents increased sensitivity to insulin and leptin signaling in hypothalamus of exercised rats. These findings provide support for the hypothesis that exercise could have appetite-suppressive actions mediated by the hypothalamic PI 3-kinase pathway

ASSUNTO(S)

leptina rats hipotalamo rato letin insulina exercicios fisicos insulin

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