PHARMACOLOGICAL STUDY OF THE EFFECT OF RADIX TRICHOSANTHIS ON TERMINATING EARLY PREGNANCY

In the present study Radix Trichosanthis was shown to terminate pregnancy in mice following subcutaneous administration on the 4 th and 5 th days of pregnancy. The ED₅₀ of Radix Trichosanthis to terminate early pregnancy in mice was 1.78±0.28 mg/kg. Megestrol acetate or HCG could decrease the effect of Radix Trichosanthis, However, 15-methyl-PGF_2α could potentiate the effect of Radix Trichosanthis.Subcutaneous injection of Radix Trichosanthis at doses capable of terminating early pregnancy significantly inhibited the decidual reaction in pseudopregnant mice. This inhibitory effect, as well as the effect to terminate early pregnancy, increased with increasing dose. In addition to its partial antagonism to the interruption of early pregnancy by Radix Trichosanthis megestrol acetate also antagonized markedly the inhibitory effect of Radix Trichosanthis on deciduoma. From these results, it may be concluded that the effect of Radix Trichosanthis to terminate early pregnancy may be related to its inhibitory effect on deciduoma.After an intramuscular injection of Radix Trichosanthis on the 7 th day of pregnancy in rats the peripheral plasma level of progesterone was unchanged Within 48 hr after administration but decreased at 72 hr. The vaginal cornification test of ovariectomized mice and uterine weight assay of mice showed that Radix Trichosanthis possessed neither estrogenic nor antiestrogenic activity. It was suggested that the inhibitory effect of Radix TrichosanthiS on deciduoma was not the result of luteolysis. The precise mechanism of the antidecidual effect of Radix Trichosanthis remains to be clarified further.