CHANGES IN CYCLIC-AMP RESPONSES TO FSH IN ISOLATED RAT SERTOLI CELLS DURING SEXUAL-MATURATION

Cyclic AMP responses to FSH in isolated Sertoli cells were examined at different stages of sexual maturation. The Sertoli cells were isolated by enzymatic digestion from rats ranging in age from 18-60 days. Immediately after their isolation or after 4-11 days of culture, the cells were incubated with FSH (NIH-FSH-S11) and/or 1mM 1-methyl-3-isobutylxanthine (MIX) for 30 min at 34°C and the levels of endogenous cyclic AMP were determined by radioimmunoassay. A dramatic decrease in cyclic AMP response to FSH was observed in the presence or absence of MIX between 18 and 36 days of age with little change occurring in older animals. At 18 days, FSH plus MIX induced a 60-fold increase in cyclic AMP level above that observed with MIX alone, compared to a 28-fold increase at 24 days and a 10-fold increase at 36 days. The basal levels of cyclic AMP were similar at all ages (about 10 pmole/mg protein) and MIX alone increased the basal levels 2-3-fold. FSH had no effect on cyclic GMP levels. These results provided direct evidence for an age related decline in cyclic AMP response to FSH in the Sertoli cells per se.