DIFFERENT TIME-COURSE PRODUCTION OF PEPTIDIC AND NONPEPTIDIC LEUKOTRIENES AND PROSTAGLANDINS E(2) AND F2-ALPHA IN THE OVARY DURING OVULATION IN GONADOTROPIN-PRIMED IMMATURE RATS

Temporal changes in ovarian leukotrienes (LTs) and prostaglandins (PGs ) were examined during ovulation to assess roles they may play in this process. Ovulation was induced in immature rats by injection with hum an chorionic gonadotropin (hCG; 10 IU, s.c.) 2 days after they had bee n primed with pregnant mare serum gonadotropin (10 IU, s.c.). The ovar ies were extirpated at various intervals after hCG administration and assayed for LTB(4), and LTC(4)/D-4/E(4) as well as PGE(2), and PGF(2 a lpha). Ovarian concentration of LTB(4) increased (P < 0.01) rapidly, r eaching a peak at 1 hour after hCG administration, then declined (P < 0.05) by 4 hours and remained low thereafter. In contrast, LTC(4)/D-4/ E(4) peaked (P < 0.01) between 1 and 2 hours, declined (P < 0.05), and then increased (P < 0.01) to achieve a second, larger peak at 10 hour s. Prostaglandin E(2) increased (P < 0.01) at 6 hours after hCG and di d nor decrease from the peak value until (P < 0.01) 14 hours after hCG . Concentrations of PGF(2 alpha) increased (P < 0.01) at 4 hours after hCG, but decreased (P < 0.01) from the peak by 10 hours. Although LTB (4), LTC(4)/D-4/E(4), PGE(2), and PGF(2 alpha) all increased during ov ulation, the time-course differed. This suggests that each eicosanoid may play a distinct role in the process of follicular rupture.