[Gonadotropic regulation of estrogen secretion by rat ovarian follicles (author's transl)]

The present studies were carried out to clarify the mechanisms of estrogen secretion by ovarian follicles. Rats of the Wistar-Imamichi strain at 27 days of age were treated subcutaneously with 75 IU of PMS. Ovaries were resected 24 or 48 hours after treatment and incubated for 2 hours or perifused for 5 hours using medium-199 containing ovine NIH-LH and NIH-FSH at 37 degrees C. Concentration of steroids in medium and tissue was determined by RIA. Estradiol 17-beta (E2) concentration in the perifusion effluent rose markedly following LH stimulation and rose slightly following FSH or dibutyryl cyclic-AMP stimulation. Prolactin, ACTH, PG E2 and PG F2 alpha were noneffective. LH appeared to stimulate slightly progesterone and androgen secretion by ovaries perifused. The stimulatory effects of LH on E2 secretion disappeared in ovaries from which follicular fluids were removed by punctuation with a small needle. E2 concentration in incubation medium and the total amount of E2 concentration in medium and tissue were significantly increased by treatment of LH, while the concentration in tissue was decreased by the treatment. However, LH showed no effect on E2 concentration in incubation medium and tissue of ovaries with punctured follicles. These results suggest that in the fully developed follicles LH stimulates the release of E2 stored in follicular fluids, in addition to E2 biosynthesis. E2 granules were stained by an enzyme-labeled antibody technique. They were observed only in the thecal or interstitial cells of ovaries 24 hours after PMS injection and then 48 hours after injection they also appeared in the granulosa cells either. These results suggest that in the fully-developed follicles E2 is produced in the thecal and granulosa cells and stored in follicular fluids.