Inhibition of the formation of 13,14-dihydroprostaglandin F2-alpha induced by chlorpromazine in rat ovary

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.

Inhibitory effect of chlorpromazine on rat reproduction: a test of administration for nine weeks before breeding

The effect of chlorpromazine (CPZ) administration prior to insemination on reproduction was studied using male and female Sprague-Dawley strain rats evaluated over three generations. CPZ in doses of 12.5, 25, 50, and 100 mg/kg was administered to both male and female rats orally every day for 9 weeks before mating with the following results: 1) The duration of the estrous cycle was prolonged in the F0 females. 2) The incidence of insemination and pregnancy of the F0 males and females as well as the number of surviving fetuses and newborns showed a tendency to decrease. 3) The body weight of the rats in F0 and F1 generations decreased depending on the dose of CPZ, but the body weight of the F2 generation increased. 4) The wet weight of the major organs of the rats in F0 and F1 generations was affected by administration of CPZ at 100 mg/kg. The weights of the liver, kidney, adrenal, pituitary, testis, and prostate glands in males and the kidney, adrenal gland, and ovary in females were increased, whereas the weights of the pituitary and the uterus were decreased in females. These results suggest that premating administration of CPZ to the parent rats exerts influence on the reproduction of the F0 and F1 generations.

Effect of hCG on the 13,14-dihydro-prostaglandin F2-alpha forming capacity of the ovary after ovulation in PMSG-primed immature female rats

We have examined the change in the ovarian 13,14-dihydro-prostaglandin F2 alpha (13,14H2-PGF2 alpha) forming capacity after the first ovulation induced by injection of pregnant mare serum gonadotropin (PMSG 5 IU, sc) at 26 days of age. After ovulation, the 13,14H2-PGF2 alpha forming capacity in the whole ovary (WO) and in non-luteal ovarian tissues (WO-CL) gradually decreased, whereas a rapid decrease of the synthesizing capacity was observed in corpus luteum (CL). The capacity in WO 4 days after ovulation (33 days of age) was markedly stimulated by human chorionic gonadotropin (hCG 10 IU, ip) administration, whereas CL at 33 days of age did not respond to the stimulatory effect of hCG. A single injection of hCG on day 7 after hypophysectomy resulted 12 hrs later in a significant increase in the forming capacity of 13,14H2-PGF2 alpha in WO-CL. These results indicate that the 13,14H2-PGF2 alpha forming capacity in CL rapidly decreases after the first ovulation and the WO-CL, but not CL, retain the ability to form 13,14H2-PGF2 alpha in response to exogenous gonadotropin for a long time.

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

The purpose of this work was to investigate the effects of gonadotropin on the production capacity of ovarian 13,14-dihydro-prostaglandin F2-alpha (13,14H2-PGF2 alpha) and whether or not this capacity had any relation to the process of ovulation in rat. To induce the first ovulation, immature rats were injected subcutaneously with PMSG (5 IU/rat) at 8:00 at 26 days of age and some of these rats were followed by an intraperitoneal injection of hCG (10 IU/rat) at 57 hrs after PMSG treatment. The 13,14H2-PGF2 alpha production capacity was unchanged as compared with vehicle control until 57 hrs after PMSG treatment. However, the capacity showed a striking increase at 60 hrs after PMSG treatment. A maximal increase of about 7 fold was observed at 9 hrs after hCG injection just before ovulation. The production capacity of the Graafian follicle (GF) and the part (WO-GF) of the whole ovary (WO) from which the GF is removed at 2:00 on day 29 and the capacity of early corpus luteum at 8:00 on day 29 was greater than that of GF and WO-GF at 0:00 on day 29. These results suggest that the 13,14H2-PGF2 alpha production capacity in rat ovary is regulated by gonadotropin and is closely associated with the process of ovulation.

Mode of action of chlorpromazine (CPZ) blockage on 13,14-dihydroprostaglandin F2-alpha formation in rat ovary

The mode of action of the inhibitory effect of CPZ on 13,14-dihydroprostaglandin F2-alpha (13,14H2-PGF2-alpha) formation in rat ovary was examined. The inhibition of 13,14H2-PGF2-alpha formation and of ovulation induced by a proestrus were completely recovered by an injection of hCG (25 IU/rat) or LH-RH (500 ng/rat) at 15:00 on the same day. 13,14H2-PGF2-alpha formation and ovulation were not inhibited by a single injection of prolactin (PRL:6 IU/rat) at 13:00 on the day of proestrus. Repeated injection of PRL inhibited cyclic ovulation and 13,14H2-PGF2-alpha formation. The estrus cycle of PRL treated animals showed a continuous state of diestrus. Although 13,14H2-PGF2-alpha formation and ovulation were inhibited by the repeated injection of CPZ, the repeated-simultaneous injection of CPZ and bromocriptine at 10:00 once a day for 3 days from the first day of diestrus partly restored both and entirely reversed the suppression of the cyclic-changes in the in the vaginal smear pattern. These results indicate that the inhibition of 13,14H2-PGF2-alpha formation induced by a single injection of CPZ probably occurs via the suppression of LH-RH release from the hypothalamus, whereas PRL secretion may participate in the inhibitory effects of repeated injections of CPZ.