Pituitary cell activities in gonadectomized rats treated with estrogen.

The incorporation of 14C-leucine into LTH and STH, the uptake of 3H-estradiol into the pituitary and the appearance of the LTH and LH cells were studied in male and female rats gonadectomized at the age of 30 days and chronically treated with estradiol (E). The biosynthesis of LTH in the pituitary of ovariectomized rats was decreased 15 and 60 days after the operation to the level of intact males. This decrease is followed by the reduction of the number of immunochemically stained LTH producing cells. Chronical administration of estradiol stimulated the LTH synthesis and maximal incorporation of 14C-leucine was obtained in ovariectomized rats. Maximal relative increase of labeled LTH was noticed in the pituitaries of intact male rats treated with E. STH synthesis is inhibited by treatment with E and maximal decrease was obtained in intact males. The luteinizing LH cells were still hypertrophic in the pituitaries of gonadectomized E treated rats, but the number of castration cells was reduced. On the basis of these results we can conclude that the castration of 30-day-old rats of both sexes does not alter the sex difference in the reaction of LTH and STH cells to estradiol.