[Effect of prostaglandin E2 and F2 alpha on steroid biosynthesis in rat ovary (author's transl)].

Conversion in vitro of pregnenolone to progesterone by the ovaries from immature rats after treatment of PMS and HCG was inhibited by addition of PGE2 (1.4 X 10(-7)M) or PGF2 alpha (1.4 X 10(-7)M). Result of conversion in vitro of pregnenolone to progesterone and estradiol-17 beta by ovary of adult rat in estrus showed that the progesterone biosynthesis in the ovary was inhibited by PGF2 alpha (1.4 X 10(-7)M) but the releasing rate of progesterone from the ovary into the medium increased by about 1.25 fold. Progesterone in the medium decreased dramatically following incubation. Estradiol-17 beta in the ovarian tissue and in the medium did not differ from the control rate with addition of PGF2 alpha. When the effect of PGF2 alpha (1.4 X 10(-7)M) in vitro on the conversion of testosterone to estrone and estradiol-17 beta by the ovary from adult rat in estrus was studied, we found that the releasing rate of estrone from the ovary into the medium was increased by addition of PGF2 alpha; the rate was significantly different from control level after addition of PGF2 alpha 30 min of incubation (p less than 0.01). Thus a minute amount of PGE2 and PGF2 alpha influences steroid biosynthesis in the rat ovary.