Modulação da expressão de receptores opióides no hipocampo de ratos submetidos à atividade física voluntária e forçada

Abstract

Several studies have demonstrated an involvement of the opioid system (opioids and opioid receptors) on the positive effects of physical activity in function and health brain. However, this mechanism still remains unclear. Moreover, only few studies have analyzed the opioid receptors expression following physical exercise as well as the type of physical activity that could exert major influence in its expression. Therefore, the purpose of our study was to verify whether aerobic physical activity (voluntary - wheel running and forced - treadmill) alter the opioid receptor expression in the rat hippocampus. The animals were divided into three groups: group 1 (n=5) rats submitted to treadmill running for 7 consecutive days, group 2 (n=5) rats submitted to voluntary wheel running for 7 consecutive days and group 3 served as control (n=5). The animals were perfused and the brains were processed for histological analysis through immunohistochemistry. It was observed an increase in mu opioid receptor expression in CA1, CA3, hilus and dentate gyrus of forced and voluntary group. Optic density analysis for kappa opioid receptor showed an increase in CA3 in voluntary group. Our data demonstrate that the forced and voluntary physical activity induce alterations on the expression of mu and kappa receptors in the hippocampus of rats suggesting a possible envolvement of these receptors with the beneficial effect of the physical activity. © Springer-Verlag Berlin Heidelberg 2007.