Luteoprotective mechanisms of prostaglandin F2α stimulated by luteinizing hormone in the bovine corpus luteum.

Abstract

The intracellular mechanism that mediates the stimulatory effect of prostaglandin F2α(PGF2α) on progesterone secretion by bovine luteal cells is not well understood. In the presentstudy, we investigated to test the hypothesis that PGF2α stimulates progesterone secretion throughactivation of protein kinase C (PKC) by using a cell culture system. Bovine mid-luteal cells (Days8–12 of the estrous cycle) were cultured for 24 h and then exposed to varying concentrations ofPGF2α (10–8, 10–7, 10–6 M) or luteinizing hormone (LH; 100 ng/ml) for 4, 6, or 16 h. Treatment of thecells with the highest dose of PGF2α (10–6 M) or LH resulted in increases in progesterone secretionfor all three exposure times. Following down-regulation of PKC with a tumor-promoting phorbolester, phorbol 12-myristate 13-acetate (PMA; 10–6 M), the stimulatory effect of PGF2α was no longerevident, whereas the response to LH was unaffected.These results support the hypothesis that the luteotropic action of PGF2α is mediated by theactivation of intracellular PKC.