[Effect of RU486 on collagenolytic enzyme activities in immature rat ovary]

To investigate the role of progesterone (P) in the ovulatory process, RU486 (RU) (10mg/kg), an antiprogesterone, was administered to PMS-hCG-treated immature female rats (22 days old). As for the collagenolytic enzymes (CE), the activities of BANA hydrolase and DNP peptidase were measured by using synthetic substrates alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl and DNP Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH, respectively. Serial assays were performed at 0, 2, 4, 6, 7, 8, 9, 10 and 12 hours after the hCG injection. In the control, the CE activities were significantly increased after the hCG injection at 8-9 hours in BANA hydrolase and 7-10 hours in DNP peptidase, respectively. By administering RU concomitant with hCG, the preovulatory increase in the CE activities was totally suppressed. Following the P(10mg/kg) injection at 4 hours after hCG and RU injections, the CE activities showed the greatest recovery, approaching the control range. In the ovulatory process of the rat ovary, P plays an important role through its regulatory effects on the collagenolytic enzymes, and this P effect seems to be most prominent around 4 hours after a LH surge.