[Age-dependent changes in the adenylate cyclase system of rat ventral prostate]

Changes in beta-adrenoceptors, GTP binding (G) proteins and adenylate cyclase (AC) activity of ventral prostates of rats during aging were studied in these experiments. The density of beta-adrenoceptors increased markedly after birth, reaching a maximum in the tissues at 16 weeks of age and remained at this level for about 90 weeks. When stimulated by isoproterenol, the AC activity increased 4- and 22-fold in 2- and 8-week-old rats, respectively, but only 7-fold in both 16- and 104-week-old rats. Activation of AC by forskolin was the greatest during the 2 weeks after birth and then showed a sharp decrease, reaching a plateau in the tissues at 8 weeks. Bmax value of [35S]GTP gamma S binding to the tissues was the largest at 8 weeks. Pretreatment of the tissues with pertussis or cholera toxin caused age-dependent changes in both the binding abilities of Gi and Gs proteins to GTP that coincided with changes in the binding of G proteins to GTP. There was no difference between the abilities of Gi and Gs proteins to bind to GTP in the tissues of rats of the respective age. These results show that changes in the binding ability of G proteins to GTP influence the function of ventral prostates of rats during the aging process, and this is mediated through the regulation of AC activity.