A gonadotropin-like thermostable peptide, prepared from bovine anterior pituitary, inducing spermiation in the frog Rana esculenta (L.) and binding to a rat ovarian FSH receptor.

A thermostable peptide, inducing sperm release in Rana esculenta L. and having immunological properties which resemble those of the gonadotropins but nonidentical with any one of the gonadotropins or their subunits, has been prepared from pars distalis of bovine anterior pituitaries by means of acetic acid extraction, heating, ethanol precipitation, and reverse-phase high-performance liquid chromatography (HPLC). During the purification, the biological activity was regularly followed by means of the potency of collected fractions to induce sperm release in frogs. Using HPLC (5 micron C18 silica), the activity was eluted with 38% of acetonitrile:water:trifluoroacetic acid (80:19.5:0.5) and 62% of 0.5% trifluoroacetic acid, pH 3.3. The active principle was also found to bind to a rat ovarian follitropin (FSH) receptor. In contrast, bovine FSH and LH treated identically to the peptide lost all such affinity, indicating that the peptide is not created from either of these during the purification procedure. Further, the peptide was, like FSH, also shown to stimulate aromatase activity in intact Sertoli cells from immature male rats in vitro.