Stimulatory effect of Sertoli cell culture medium on the FSH release by pituitary halves in vitro.

The influence of the medium collected from cultured rat Sertoli cells on the spontaneous and LHRH-stimulated release of gonadotropins by incubated rat pituitary halves was examined. The homogeneity of the cultured population of Sertoli cells taken from 20-day-old rats ranged up to 98%. The cells in culture responded to FSH stimulation with characteristic morphological changes and with increased secretion of estradiol-17 beta. The hemi-pituitaries obtained from sexually mature male rats were incubated for 5 hours in the presence of Sertoli cell culture medium (SCCM) or its fractions obtained by use of ultrafiltration. The SCCM fraction deprived of MW less than 10 kD compounds exhibited a typical inhibin-like activity, whereas crude SCCM as well as its low-molecular-weight fraction stimulated the basal FSH release to about 150% and 175% of the control values, respectively. These fractions exerted an inhibitory effect on the LHRH-stimulated secretion of both LH and FSH. It is concluded that Sertoli cells cultured in chemically defined medium release, apart from inhibin, a non-steroidal, heat-labile substance of MW less than 10 kD which stimulates the basal secretion of FSH and LH and inhibits the LHRH-stimulated secretion of both gonadotropins from incubated rat hemi-pituitaries.