Receptor changes in the nucleus tractus solitarii of the rat after exercise training

Purpose: The aim of the present study was to evaluate neurotransmitter rece ptor changes in the nucleus tractus solitarii (NTS) of the rat after exerci se training. Methods: Twelve Wistar Kyoto rats were used. Six rats were sub mitted to a progressive training program in which they ran on a treadmill 5 d(.)wk(-1) for 13 wk (trained). The other rats were kept as controls (sede ntary). After this period, the rats were killed and the brains processed fo r quantitative receptor autoradiography. Coronal brain sections were obtain ed using a cryostat and were incubated with a specific buffer solution cont aining [H-3]vasopressin or (3)Hp-aminoclonidine. Results: In the NTS of the trained rats, a decrease in the values of binding parameters (IC50 and K-D ) of vasopressin receptors was observed, indicating an increase in the affi nity of vasopressin receptors. On the other hand, a decreased affinity was observed for alpha (2)-adrenoceptors in the NTS of the trained rats in comp arison with the sedentary animals. Conclusion: Exercise training leads to c hanges in vasopressin and alpha (2)-adrenoceptors, which may explain severa l physiological alterations occurring during physical activity.