Functional state of adenylyl cyclase signaling system in rat testis and ovary under conditions of fasting

Abstract

Sensitivity of the adenylyl cyclase signaling system (ACSS) to polypeptide hormones and biogenic amines is studied in testes and ovaries of rats after the 2- and 4-day fasting as compared with control animals. In tissues of the fasted rats there is shown a decrease in the basal activity of adenylyl cyclase (AC) and of the basal level of the GTP binding of heterotrimeric G proteins. An increase in duration of fasting from 2 to 4 days led to intensification of these changes. In the fasted rats, the AC-stimulating effects of chorionic gonadotropin, PACAP-38, and isoproterenol, realized via G protein of stimulatory type are enhanced, whereas the inhibitory effects of somatostatin on the AC activity realized via G protein of the inhibitory type are reduced. In testes of the fasted rats the stimulating effect of serotonin on AC via both types of G proteins increased, whereas the inhibitory effects of the hormone decreased. Thus, under conditions of fasting, in rat testes and ovaries the ACSS sensitivity to regulatory effects of hormones is changing: their stimulatory effects are increased, while its inhibitory effects, on the contrary, are decreased. We suggest that these changes are one of the key mechanisms of adaptation of organism to deficiency of nutritional resources to be aimed at intensifying the tissues catabolic processes, preferably lypolysis.