The effect of LH on cyclic AMP and progesterone in rat ovaries in vivo.

LH injected into the abdominal vein of immature female rats increased ovarian cyclec AMP levels within 1 min, and the effect lasted at least 2 hr. In PMS stimulated rats, a maximal effect on cyclic AMP levels was obtained with 5 mug of LH 10 min after injection. Significant effects were obtained with as little as 0.1 mug. The minimum effective dose required to increase ovary cyclic AMP levels in proestrus rats was 0.05 mug of LH. While 0.01 mug did not affect cyclic AMP levels, an increase in ovary progesterone was found. In other experiments, the response of cyclis AMP to LH in vivo was greater in immature ovaries than in those from animals pretreated with PMS and hCG. Small increases in cyclic AMP levels were also seen with FSH in PMS and PMS + hCG treated animals and with prostaglandin E2 and prolactin in PMS treated rats. These results parallel, to some extent, previous results found in vitro, and show that very small doses of LH can stimulate ovary cyclic AMP increases in vivo.