Identification of inhibin secreted by cynomolgus monkey Sertoli cell cultures

An inhibin was identified in the media of primary Sertoli cell-enriched cultures from the cynomolgus monkey, Macaca fascicularis, and some of its biochemical properties were studied. Conditioned monkey Sertoli cell culture medium (m-SCCM), when added to pituitary cells from 6-week-old male rats, inhibited the basal secretion of FSH but not that of LH. This specificity was lost after the addition of GnRH; mSCCM inhibited not only FSH but also LH release, determined by both RIA and mouse interstitial cell bioassay, from pituitary cells exposed for 6 h to 10 nM GnRH. FSH-inhibiting activity persisted when m-SCCM was boiled for 30 min, but activity was lost after incubation for 1 h at 37 C with 0.1% trypsin. m-SCCM inhibin activity was completely retained by Concanavalin A-Sepharose and could be eluted with 0.2 M alpha-methyl-D-glucoside. Gel filtration high pressure liquid chromatography with a Superose-12 column revealed inhibin activity between 20-60K, with the greatest activity at 40K. Our results indicate that primate Sertoli cells produce an inhibin-like factor which could play a role in controlling gonadotropin secretion in males.