Involvement of cyclic AMP and protein synthesis in the desensitization of the prepubertal rat ovary.

Luteinizing hormone (LH) stimulates cyclic AMP (cAMP) production in ovarian cells. After the initial stimulation there is a development of refractoriness (desensitization) to a subsequent LH stimulation. The present investigation was designed to study the role of cAMP in this desensitization process and the influence of protein-synthesis inhibitors. Ovaries from 23-day-old rats were preincubated in buffer, dibutyryl-cAMP, 8-bromo-cAMP or LH. After a washing period in buffer, the ovaries were incubated in the presence of LH. Those ovaries preexposed to the cAMP analogues showed a reduced cAMP-production to LH. This reduction was found to be both dose- and time-dependent, but was never as marked as after preincubation with LH. Desensitization developed more slowly after preincubation with cAMP than with LH. Inhibitors of protein synthesis (puromycin, cycloheximide) completely abolished the cAMP-induced desensitization but only partially prevented the LH-induced desensitization. These results show that processes, dependent and independent of cAMP, are involved in the desensitization after LH stimulation of the prepubertal rat ovary.