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S Stacy

Publications and source records attributed to S Stacy.

8 recordsLinked to original sources
PubMed1997

Termination of early pregnancy in the rat by a single dose of human menopausal gonadotropin.

Human menopausal gonadotropin (hMG) is commonly used to induce ovarian follicular development and ovulation in infertile women. This report is a preliminary analysis of the ability of hMG to cause folliculogenesis and ovulation in pregnant laboratory animals. Wistar rats were injected subcutaneously with 0.5 mg of hMG on selected days of pregnancy. In addition, 2 days after receiving hMG, one group of animals was injected with 50 IU of human chorionic gonadotropin (hCG) as a substitute for an ovulation-inducing dose of luteinizing hormone. A single dose of hMG caused follicular development and ovulation in the pregnant animals. Furthermore, the results show that such hormone treatment usually terminated the gravid state of the animals. The frequency of pregnancy termination was greater (1) When hMG was administered during the first quarter of the 21-day gestation period; (2) When higher doses of hMG were used; and (3) When the hMG injection was followed 2 days later by hCG. In conclusion, hMG can terminate early pregnancy in a laboratory animal like the rat, and this observation raises the possibility that it may also act as an abortifacient agent in humans. Therefore, a more extensive analysis of the effects of hMG on pregnancy is warranted.

Abortifacient Agents↗
PubMed1992

Inhibition of ovulation in the gonadotropin-primed immature rat by exogenous prostaglandin E2.

In the past two decades there have been innumerable reports that prostaglandins (PGs) are essential for mammalian ovulation. However, we have recently found that a relatively low dose of 0.03 mg indomethacin (INDO) sc to PMSG/hCG-primed immature Wistar rats can significantly reduce ovarian PG levels without inhibiting the control ovulation rate of 60+ ova/rat (1-3). In view of this information, the present study was an effort to duplicate the earlier reports that PGs can reverse the "inhibitory" effect of INDO on ovulation. In control animals, which received PMSG and hCG only, the ovulation rate was 63.8 +/- 4.5 ova/rat. This rate was reduced to 4.1 +/- 1.1 ova/rat when the animals were injected with 1.0 mg INDO at 3 h after hCG. In no instance was this inhibition reversed when the animals were treated with 1.0 mg of PGE2 or PGF2 alpha, or a combination of both prostanoids in either a single dose at 3 h after hCG, or in 4x doses at 2-h intervals beginning at 3 h after hCG. Furthermore, in animals that did not receive INDO, the ovulation rate in PGE2-treated animals was reduced to 20.0 +/- 6.7 ova/rat, and in animals treated with PGE2 and PGF2 alpha (combined) it was reduced to 19.4 +/- 6.5 ova/rat. In summary, not only did the PGs fail to reverse the anti-ovulatory effect of INDO, PGE2 actually suppressed the ovulation rate.

Animals↗
PubMed1992

Epostane and indomethacin actions on ovarian kallikrein and plasminogen activator activities during ovulation in the gonadotropin-primed immature rat.

Kallikrein and plasminogen activator (PA) are serine proteases that have been implicated in the ovulatory process. Epostane and indomethacin are anti-ovulatory agents that inhibit steroid and eicosanoid synthesis, respectively. This study examines the effects of these two anti-ovulatory agents on ovarian kallikrein and PA activities during ovulation. The proteases were assayed by their actions on chromogenic peptide substrates S-2266 and S-2251, respectively. The ovulatory process was induced in 25-day-old Wistar rats by giving them hCG (10 IU, s.c.) 2 days after the animals had been primed with eCG (10 IU, s.c.). Control animals ovulated approximately 60-70 ova/rat, with the first ova appearing in the oviducts at 10-12 h after hCG administration, and this was the same time ovarian kallikrein and PA activities reached a peak. When doses of epostane ranging from 0.1-5.0 mg/rat or doses of indomethacin ranging from 0.03 to 3.16 mg/rat were administered s.c. at 3 h after hCG, the two drugs inhibited ovulation and ovarian kallikrein and PA activities in a dose-dependent manner. However, the anti-ovulatory action of the two drugs was more closely correlated with suppression of kallikrein activity than with PA activity. Treatment of the animals with exogenous progesterone reversed the inhibitory action of epostane, but not of indomethacin. The results suggest that the increase in ovarian progesterone at the time of ovulation may influence ovarian kallikrein and PA activities.

Age Factors↗