Reproduction Abstracts

Hyperandrogenism and dysregulated follicle development both characterise polycystic ovary syndrome (PCOS), however little is known about how androgens affect early preantral follicle development. Recent evidence suggests that androgens may act, in part, through non-classical modulation of growth factor signalling pathways. Members of the epidermal growth factor (EGF) family play a role in promoting preantral follicle development in the mouse, with receptor subtypes EGFR, ErbB2, and ErbB3 detected in primary and secondary follicles. This study aimed to investigate androgen–EGF interaction within preantral follicles.

Preantral follicles obtained from PND16 mouse ovaries (C57BL/6) were mechanically isolated and cultured in the presence of EGF (10 ng/ml) or dihydrotestosterone (DHT; 10 nM) with or without the specific EGFR inhibitor AG1478 (10 mM). Granulosa cells were isolated from PND26 mice (C57BL/6) and cultured with DHT (10 nM).

DHT increased preantral follicle growth from 24 h onwards (P<0.05). Combined treatment with EGF and DHT resulted in elevated growth above that of either treatment alone (P<0.05). DHT treated follicles displayed no change in EGFR, ErbB2, or ErbB3 mRNA, however, ErbB2 protein expression was down-regulated at 24 h (P<0.001), suggesting a role for androgens in regulating ErbB abundance, independent of transcription. The addition of AG1478 not only ablated EGF stimulated follicle growth but also attenuated the effect of DHT on growth (P<0.01) implying that the actions of DHT are mediated, at least in part, through the EGFR. Granulosa cells treated with DHT, showed a significant increase in phospho-ERK at 2 and 5 min (P<0.05), indicating the presence of non-genomic androgen signalling within mouse granulosa cells. Whether this non-classical pathway involves the EGFR is unclear and is currently under investigation. In conclusion, DHT stimulated follicle growth is mediated partly through the EGFR, likely through both genomic and non-genomic signalling in the preantral follicle.