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RESEARCH |
Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, CP 04510 México D.F., Mexico and1 Royal (Dick) School of Veterinary Studies, The Roslin Institute, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
Correspondence should be addressed to C G Gutierrez; Email: ggcarlos{at}servidor.unam.mx
The chicken ovary is organized into a hierarchy of yellow yolky follicles that ovulate on successive days. Active or passive immunization of laying hens against testosterone blocks ovulation without affecting follicle development. Testosterone may play a role in pre-ovulatory follicle maturation by stimulating granulosa progesterone production. We assessed whether this stimulus is dose-related and depends on the maturity of the donor follicle, and if it does so by stimulating granulosa cell STAR, P450 cholesterol side-chain cleavage (P450scc), and LH receptor (LHCGR) mRNAs expression. Progesterone production by granulosa cells from F1, F3, and F4 follicles, cultured for 3 h without testosterone was greater in cells collected 11–14 h than 1–4 h after ovulation. These differences in progesterone production were less pronounced after granulosa cells had been cultured for 24 h. Culture of granulosa cells for 3 or 24 h with testosterone (1–100 ng/ml) stimulated progesterone production in cells collected from F4, F3, or F1 follicles 1–4, or 11–14 h after ovulation. Testosterone (0–4000 ng/ml) alone or in combination with LH (0–100 ng/ml) increased progesterone production by F1 granulosa cells, collected 1–4 and 11–14 h after ovulation and cultured for 3 h. Finally, testosterone (10 or 100 ng/ml) increased STAR, P450scc, and LHCGR mRNAs, when added to 3 h cultures of F1 granulosa cells. In conclusion, testosterone stimulates granulosa cell progesterone production in hen pre-ovulatory hierarchical follicles irrespective of maturational state, acting alone or additively with LH. We propose that testosterone promotes granulosa cell maturation to facilitate the pre-ovulatory release of LH.
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