Inhibin production by Sertoli cell cultures

The production of inhibin by cultures of Sertoli cells from 21-day-old rats was assessed by the use of an in vitro bioassay using rat pituitary cells in culture. Sertoli cell culture media (SCCM) caused a dose-dependent suppression of the pituitary cell FSH content which was parallel with that of an ovine testis lymph preparation used as an inhibin standard. SCCM also caused a dose-dependent inhibition of FSH secreted by pituitary cells in response to 10 nM GnRH stimulation. The FSH-inhibitory activity in SCCM was destroyed by heat or trypsin digestion and could not be attributable to the steroid content of the medium, since ether extraction caused no change in the inhibitory activity. The inhibin activity in SCCM was not due to cytotoxicity in the bioassay, since the LH cell content was unchanged and the media produced no change in the release of 51Cr from labelled pituitary cells, a parameter which has been shown to be a useful test of cytotoxicity. Sertoli cell cultures produced inhibin for the 8-day duration of the cultures. The amount of inhibin produced was proportional to the number of Sertoli cells initially plated. If foetal calf serum was included for more than the initial 48 h, the spent medium caused toxic effects in the pituitary cells as evidenced by an increase in 51Cr release from 51Cr-labelled pituitary cells. Similar toxic effects were found if the lyophilized spent media contained cellular debris. A dose-dependent increase in inhibin activity was observed in the presence of graded doses of FSH (0.05-5 micrograms/ml NIH-FSH-S13).