Effects of diverse mammalian and nonmammalian gonadotropins in a rat granulosa cell bioassay for follicle-stimulating hormone.

The biopotencies of pituitary gonadotropins purified from a marsupial (kangaroo), two avian (ostrich and turkey), a reptile (turtle), an amphibian (bullfrog), and two fish (sturgeon and teleost) species were examined using an in vitro rat granulosa cell bioassay for follicle-stimulating hormone (FSH). Treatment of cultured granulosa cells with increasing concentrations of gonadotropin preparations from these species resulted in dose-dependent increases in estrogen production from negligible amounts to maximal levels of approximately 2-29 ng/culture. The relative biopotencies of these FSH preparations from most potent to least potent were in the order of human greater than ostrich greater than turkey greater than kangaroo greater than turtle greater than sturgeon greater than bullfrog greater than teleost with ED50 values of human 8.7 ng/well; ostrich 10.5 ng/well; turkey 22.5 ng/well; kangaroo 58.2 ng/well; turtle 62.5 ng/well; sturgeon 260 ng/well; bullfrog 750 ng/well; teleost greater than 1000 ng/well. In contrast, luteinizing hormone (LH) preparations were considerably less effective for ostrich, turkey, kangaroo, turtle, and bullfrog, being six-, five-, three-, and twofold less potent than FSH preparations for the same species, demonstrating the specificity of this assay for FSH. An LH preparation from bullfrog was unable to significantly stimulate estrogen production below 500 ng/ml. Thus, the present in vitro bioassay (GAB) using rat granulosa cells provides a sensitive and specific assay for measuring FSH activities of gonadotropins from diverse mammalian and nonmammalian species.