Collagenolytic enzymes and progestin in induced ovulation in rabbits with hyperprolactinemia

To clarify the possible role of collagenolytic enzymes and progestin in induced ovulation and to investigate whether progesterone interacts with these enzymes in leading to ovulation during the hyperprolactinemic state, the alterations of 2,4-dinitrophenyl-Pro-Gln-Gly-Ile- Ala Gly-Gln-D-Arg-OH peptidase (DNP-peptidase) and alpha-n-benzoyldl-Arg-beta-naphthylamide hydrolase (BANA-hydrolase) activities were measured in rabbit ovaries. The ovaries were primed with four daily sulpiride (SLP) injections followed by human chorionic gonadotropin (hCG) administration. The peripheral and ovarian progesterone, 20 alpha-hydroxypregn-4-en-3-one (20 alpha OHP) levels and ovulation rate at 14 hours after hCG administration in SLP-treated rabbits were significantly suppressed as compared with the control animals. The usual changes in DNP-peptidase and BANA-hydrolase activities in the follicular tissue at 8 and 10 hours after hCG were also altered by this abnormal hypersecretion of circulating prolactin. When progesterone was administered concomitantly with hCG to the hyperprolactinemic rabbits during ovulation induction, the ovulation rate was restored to a physiologic level comparable to that of the controls. These results suggest that both progesterone and collagenolytic enzymes are mandatory for follicular rupture induced by hCG and that progesterone may interact with these enzymes to facilitate the completion of the ovulatory process during the hyperprolactinemic state.