Control of Sertoli Cell Response to FSH: Regulation by Homologous Hormone Exposure

The effect of in vitro exposure to FSH on subsequent FSH binding and stimulation of short-term rat Sertoli cell cultures was investigated. Cultures were exposed 6 h to FSH (0.05, 0.1, 1.0, or 5.0 µg/ml), washed, and incubated for an additional 1, 2, 4, or 6 days at which times FSH binding, FSH-stimulated cAMP generation, and FSH-stimulated aromatization of testosterone (T) to estradiol (E 2 ) were determined. The initial effect of exposure to high concentrations of FSH (1.0-5.0 µg/ml) was a dose-related decrease in both hormone binding and cAMP response. In contrast, a dose-related increase in T aromatization occurred. By 4-6 days after FSH exposure, hormone binding had started to increase, and cAMP response had either returned to or was significantly increased above control values while T aromatization remained elevated without any additional increase. The initial effect after exposure to low concentrations of FSH (0.05-0.1 µg/ml) was an intermediate decrease in hormone binding with no significant change in either cAMP generation or T aromatization. By 4-6 days after FSH exposure, hormone binding and cAMP response were significantly increased above control values. T aromatization did not change. These findings suggest that FSH regulates Sertoli cell response to subsequent FSH stimulation apparently at two independent levels: one related to hormone binding and cAMP response, and the second related to the aromatization of T.