Plasminogen activator in rat ovary during the ovulatory process: independence of prostaglandin mediation

• Published in: Journal of endocrinology Vol. 97; no. 2; p. 201
• Main Authors: Shimada, H, Okamura, H, Noda, Y, Suzuki, A, Tojo, S, Takada, A
• Format: Journal Article
• Language: English
• Published: England 01-05-1983
• Subjects: Animals; Chorionic Gonadotropin - pharmacology; Female; Indomethacin - pharmacology; Ovary - metabolism; Ovulation - drug effects; Plasminogen Activators - biosynthesis; Plasminogen Activators - physiology; Prostaglandins - physiology; Rats; Rats, Inbred Strains; Time Factors
• ISSN: 0022-0795
• DOI: 10.1677/joe.0.0970201

To elucidate the possible roles of increased plasminogen activator (PA) in follicular rupture and to investigate whether prostaglandins participate in ovarian PA synthesis in vivo, enzyme activities were sequentially measured by a method using the chromogenic substrate S-2251 in immature rat ovaries primed with pregnant mare serum gonadotrophin (PMSG) followed by human chorionic gonadotrophin (hCG) either alone or with a concurrent injection of indomethacin. Before hCG injection PA activity was 0.006 +/- 0.006 (S.D.) mumol/1.6 mg ovarian tissue (wet wt) per 30 min: PA activity of a saline-treated group remained at low levels (less than 0.018 +/- 0.003 mumol/l X 6 mg tissue per 30 min). In contrast, PA activity of animals given hCG alone increased after the treatment, reaching a peak value of 0.112 +/- 0.071 mumol/l X 6 mg tissue per 30 min 12h later, before decreasing to 0.023 +/- 0.014 mumol/l X 6 mg tissue per 30 min at 32 h. Contrary to expectations, a dose of indomethacin which completely blocked ovulation had no effect on either the magnitude or the time-course of PA synthesis after hCG administration (P greater than 0.05). These results indicate that prostaglandins are not involved in the preovulatory synthesis of PA induced by hCG in rat ovaries and that PA is not a primary proteolytic enzyme for follicular rupture. It is suggested that PA has possible roles in cumulus detachment and/or proliferation of granulosa cells during the ovulatory process.