Forthcoming papers in the journal of steroid biochemistry

Abstract

The ability of gonadotropins from six mammalian species to stimulate estrogen and progesterone production was investigated in granulosa cells of hypophysectomized estrogen-primed immature female rats. Granulosa cells were cultured for 2 days in the presence of Δ4-androstenedione (10−7m) with or without various gonadotropin preparations. Treatment with follitropin (follicle-stimulating hormone, FSH) from human, rat, ovine, porcine, equine, and bovine origins resulted in dose-dependent increases in steroidogenesis from negligible amounts to maximal levels of approximately 4–8 and 12–30 ng/105 cells for estrogen and progesterone, respectively. The ED50 values of the FSH preparations for stimulation of steroidogenesis were: human: 1–4 ng/ml; ovine: 2.5–30 ng/ml; rat: 1.6 – 4.0 ng/ml; porcine: 7.5 – 20 ng/ml; equine 2.5–6 ng/ml; and bovine > 100 ng/ml. Lutropin (luteinizing hormone, LH) from rat, ovine, bovine, and porcine origins, human chorionic gonadotropin (hCG), the α-subunit of human FSH and the β-subunit of human LH were ineffective in stimulating steroidogenesis, indicating the specificity of the assay system for FSH. In a high concentration (600 ng/ml), the β-subunit of human FSH-stimulated steroidogenesis to a small extent. Furthermore, pregnant mare serum gonadotropin and equine LH also caused a dose-dependent stimulation of estrogen and progesterone production, the half-maximal response values (ED50) being 1.8 – 4 and 7.5 – 10 ng/ml, respectively. This is consistent with previous in vivo and in vitro findings, showing the potent FSH activities of these hormones. Thus, the cultured rat granulosa cell system provides a sensitive assay for measuring FSH activities of gonadotropins from various mammalian species.