Androgens Augment the Mitogenic Effects of Oocyte-Secreted Factors and Growth Differentiation Factor 9 on Porcine Granulosa Cells

• Published in: Biology of reproduction Vol. 73; no. 4; pp. 825 - 832
• Main Authors: HICKEY, T. E, MARROCCO, D. L, AMATO, F, RITTER, L. J, NORMAN, R. J, GILCHRIST, R. B, ARMSTRONG, D. T
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.10.2005
• Subjects: Androgen Antagonists - pharmacology; Androgens - pharmacology; Animals; Biological and medical sciences; Bone Morphogenetic Protein 15; Cell Proliferation; Cells, Cultured; Coculture Techniques; Dihydrotestosterone - pharmacology; Dose-Response Relationship, Drug; Female; Flutamide - analogs & derivatives; Flutamide - pharmacology; Follicle Stimulating Hormone - pharmacology; Fundamental and applied biological sciences. Psychology; Granulosa Cells - drug effects; Granulosa Cells - physiology; Growth Differentiation Factor 9; Insulin-Like Growth Factor I - pharmacology; Intercellular Signaling Peptides and Proteins - genetics; Intercellular Signaling Peptides and Proteins - pharmacology; Mammalian female genital system; Mice; Mitogens - pharmacology; Morphology. Physiology; Oocytes - secretion; Progesterone - secretion; Recombinant Proteins - genetics; Recombinant Proteins - isolation & purification; Recombinant Proteins - pharmacology; Swine; Testosterone - pharmacology; Vertebrates: reproduction; Androgen; growth factors; follicle; granulosa cells; Germinal cell; Pig; Ovary; Vertebrata; Reproduction; Mammalia; Animal; Female genital system; Androgen receptor; Artiodactyla; Granulosa; Sex steroid hormone; Differentiation; Ovarian follicle; Ungulata; Oocyte; Growth factor
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.104.039362

In this study, we test the hypothesis that the growth-promoting action of androgens on granulosa cells requires paracrine signaling from the oocyte. Mural granulosa cells (MGCs) from small antral (1–3 mm) prepubertal pig follicles were cultured in the presence or absence of denuded oocytes (DO) from the same follicles to determine whether mitogenic and/or steroidogenic responses, to combinations of FSH, insulin-like growth factor 1 (IGF1), and dihydrotestosterone (DHT) were influenced by oocyte-secreted factors (OSFs). To further explore the identity of such factors we performed the same experiments, substituting growth differentiation factor 9 (GDF9), a known OSF, for the DO. OSFs and GDF9 both potently enhanced IGF1-stimulated proliferation, and inhibited FSH-stimulated progesterone secretion. Alone, DHT had little effect on DNA synthesis, but significantly enhanced the mitogenic effects of OSFs or GDF9 in the presence of IGF1. Denuded oocytes, GDF9, and DHT independently inhibited FSH-stimulated progesterone secretion, and androgen, together with DO or GDF9, caused the most potent steroidogenic inhibition. Focusing on mitogenic effects, we demonstrate that both natural androgen receptor (AR) agonists, testosterone and DHT, dose-dependently augmented the mitogenic activity of DO or GDF9. Antiandrogen (hydroxyflutamide) treatment, which is used to block androgen receptor activity, opposed the interaction between androgen and GDF9. In conclusion, androgens stimulate porcine MGC proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9, via a mechanism that involves the AR. These signaling pathways are likely to be important regulators of folliculogenesis in vivo, and may contribute to the excess follicle growth that is observed in androgen-treated female animals. Abstract Androgens directly stimulate porcine mural granulosa cell proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9