Relationship between the production capacity of ovarian 13,14-dihydro-prostaglandin F2-alpha and the process of ovulation in immature female rats pretreated with gonadotropin

Effects of carbamazepine on the first ovulation in gonadotropin-primed immature female rats

1. The effects of carbamazepine (CBZ) and its possible mechanisms on the first ovulation were investigated in immature female rats. The first ovulation was induced by administration of equine chorionic gonadotropin (eCG) at 0800 h at 26 days of age. 2. A single s.c. injection of 360 mg x kg(-1) CBZ at 1300 h on the first pro-oestrus (day 28) completely inhibited the first ovulation on the morning of day 29. A marked elevation in 13, 14-dihydro-prostaglandin F2alpha (13, 14H2-PGF2alpha) forming capacity, a sensitive indicator of luteinizing hormone (LH) surge, was not detected in the CBZ-treated group at 0800 h on day 29 (72 h after eCG treatment). The elevation in serum LH levels at 57 h after eCG treatment was not observed in the CBZ-treated group, either. The blocking of the first ovulation and 13, 14H2-PGF2alpha forming capacity were recovered by an i.p. injection of human CG on day 28 in all animals. 3. However, the first ovulation was not blocked by repeated injections of 360 mg x kg(-1) CBZ at 1300 h once daily for 3 days (days 26 - 28). The repeated injections of CBZ caused a great fall (64% decrease) in the serum levels of CBZ at 4 h after the final CBZ injection as compared with the case of a single injection of CBZ and resulted in a delay for 5 h the occurrence of LH surge, which is normally observed around 57 h after eCG injection. 4. A significant increase in the activity of microsomal CBZ catabolism by the repeated injections of CBZ was quantitatively verified by the HPLC analysis. But, the activity of CBZ metabolism in the single injected-animals showed almost similar levels to that in the control. 5. The present results demonstrated that a single injection of CBZ blocks the ovulation by inhibiting LH surge but that the failure of the inhibition of ovulation by repeated injections of CBZ is due to a decrease in serum CBZ levels mediated through CBZ-induced hepatic enzyme induction.

Inhibition of the first ovulation and ovarian prostaglandin F2 alpha metabolism by danazol in rats

The present study was conducted to investigate the mode of action of danazol by monitoring the first ovulation, serum luteinizing hormone (LH) levels and ovarian prostaglandin (PG) F2 alpha metabolism in pregnant mare serum gonadotropin (PMSG)-primed immature female rats. When danazol (750 mg/kg) was given p.o. once a day for 5 days (day 24-28), the occurrence of the first ovulation, the increase in capacity to form 13,14-dihydro-PGF2 alpha and PGF2 alpha levels induced by PMSG (5 IU) injected on day 26 were clearly inhibited on day 29. Danazol also markedly suppressed the LH surge occurring on day 28. Although the danazol-induced blockage of ovulation was restored by injection of human chorionic gonadotropin, the number of oocytes was significantly decreased as compared with that of controls. The present data indicate that the inhibitory actions of danazol on ovulation and ovarian PGF2 alpha metabolism may occur via some direct effects on the ovary in addition to the suppression of gonadotropin release from the pituitary gland.

Basic fibroblast growth factor in rat corpus luteum stimulates prostaglandin F2-alpha production

Rat luteal cells (LC) were incubated with or without basic fibroblast growth factor (bFGF) in a serum-free medium. Prostaglandin F2 alpha (PGF2 alpha) production was stimulated in a dose-dependent manner at 0.03-1 ng/ml of bFGF. One ng/ml of bFGF caused approximately 5-fold the increment of PGF2 alpha at every stage of LC after 48 hrs of incubation. bFGF also raised progesterone secretion from LC, and this stimulatory effect on progesterone was more distinguishable in an early-, than a middle- and a late-stage. Additionally, bFGF concentration throughout the luteal phase was assessed using western blot analysis. The protein with typical molecular weight 18 kDa form was in high concentration throughout the luteal phase. These results suggest that bFGF may play a role in the regulation of PGF2 alpha and progesterone production as autocrine, but not in mitosis in corpus luteum.