contraceptives--postcoital and Fetal-Resorption

This study investigates the potential post-coital contraceptive mechanisms of the crude extract of Sri Lankan marine red algae, Gelidiella acerosa, using rats. The dose used was 1000 mg/kg/day and the route of administration was oral. The results showed that the crude extract possessed potent post-coital contraceptive activity when administered on days 7-8 of pregnancy indicating the presence of a narrow window in its action. The post-coital contraceptive activity was due to an elevated post-implantation loss (by 89%) resulting from fetal death between days 9-14 of pregnancy. The extract was neither estrogenic nor anti-estrogenic nor stressor but appeared to be anti-progestational (reduced ovarian progesterone output). It is suggested that the crude extract may reduce the ovarian progesterone release possibly via anti-platelet and PGE2-depressing activity.

Topics: Animals; Contraceptives, Postcoital; Embryonic Development; Estrogen Antagonists; Female; Fetal Resorption; Hormone Antagonists; Male; Pregnancy; Progesterone; Rats; Rhodophyta; Time Factors

The effect of various doses of anordrin and RU 486, alone or combined, on serum progesterone (P) levels, fetal resorption, and recovery of ovulation was studied in mice. Each drug was given as a single sc injection on day 7 of pregnancy and autopsy was performed on days 8, 9, or 11. Serum P was normal at 24 h but fell significantly 48 h after treatment with anordrin (0.05 mg). Doses of 0.05 or 0.2 mg anordrin were effective in interrupting pregnancy in 30% and 70% of pregnant mice, respectively. RU 486, 0.01 mg per mouse, induced a pronounced decrease of P levels 24 h after treatment and interrupted pregnancy in 50% of pregnant mice. The combined treatment with submaximal doses of anordrin plus RU 486 did not further decrease P levels, but increased the proportion of mice with fetal resorptions to 90%. The combination of small doses of anordrin with RU 486 had an additive effect on pregnancy termination. The additive effect required a dose of RU 486 above the threshold level. Direct observation of aborted fetuses indicated that the resorptive process occurred earlier with RU 486 than with anordrin. Recovery of ovulation was associated with pregnancy termination in a high proportion of mice treated with either drug or their combination.

Topics: Abortion, Induced; Animals; Contraceptives, Postcoital; Dose-Response Relationship, Drug; Drug Synergism; Female; Fetal Resorption; Injections, Subcutaneous; Mice; Mifepristone; Norandrostanes; Ovulation; Pregnancy; Pregnancy, Animal; Progesterone

Topics: Administration, Intravaginal; Administration, Oral; Animals; Contraceptives, Postcoital; Contraceptives, Postcoital, Synthetic; Cricetinae; Embryo Implantation; Female; Fetal Resorption; Injections, Subcutaneous; Mesocricetus; Oxadiazoles; Pregnancy; Pregnancy, Animal