Follicle-stimulating hormone-mediated induction of functional luteinizing hormone/human chorionic gonadotropin receptors during monolayer culture of porcine granulosa cells.

The LH/hCG receptor content of porcine ovarian granulosa cells from 1- to 3-mm follicles can be increases to 4--5 times the preculture level during monolayer culture in serum-containing media supplemented with insulin and FSH. The binding of [125I]iodo-hCG declines during the first 2 days of culture, but then uniformly increases through 6 days, achieving a 14- to 15-fold increase relative to the 2-day level under optimal conditions. Analysis of receptor binding by autoradiography indicates that after 2 days, the number of cells specifically binding [125I]iodo-hCG increases significantly during culture, as does the intensity of binding on receptor-bearing cells. Granulosa cells in monolayer culture exhibit heterogeneous receptor induction, indicating that normalized [125I]iodo-hCG binding data cannot be used to estimate receptor concentration per cell. Receptor affinities in the initial and induced populations are identical. LH/hCG receptors induced in granulosa cells during culture are functional, as demonstrated by specific hCG-stimulated progesterone secretion. 17 beta-Estradiol produces a differential effect in vitro, generally increasing [125I]iodo-hCG binding with respect to FSH-induced levels but consistently depressing the subsequent hCG-stimulated steroidogenic response of cells bearing the induced receptor. The porcine granulosa cell monolayer system thus appears to be a useful model with which to study, in vitro, mechanisms of steroid and gonadotropin regulation of granulosa cell differentiation and overall follicular development.

Duke Scholars

Author David William Schomberg Obstetrics and Gynecology, Reproductive Sciences