Biological determination of inhibin in rat ovarian-cell culture medium

Rat ovarian-cell culture medium contains steroids and inhibin material that are able to influence basal and LHRH-stimulated secretion of FSH and LH from dispersed pituitary cells. Studies on procedures to remove steroids, such as ethyl acetate extraction and charcoal: dextran adsorption, showed that adsorption of the culture medium with 0.5 to 1.0% charcoal and 0.05 to 0.1% dextran, respectively, was the optimal method to eliminate most of the steroids in the medium without a detrimental effect on inhibin activity. The inclusion of serum or bovine albumin in the culture medium after the culture protected the inhibin from adsorption by the charcoal: dextran treatment. The inhibin present in the rat ovarian-cell culture medium treated with 1.0% charcoal: 0.1% dextran behaved like the inhibin reference standard (from rete testis fluid of the sheep: RTFS) in the basal secretion of FSH and the LHRH-stimulated secretion of FSH and LH in the in-vitro bioassay.