Endocrine Abstracts

Polycystic ovary syndrome (PCOS) is the commonest cause of anovulatory infertility in women. Recent evidence suggests that early folliculogenesis is disordered and may contribute to development of anovulation in PCOS. Early follicle development in PCOS is characterised by increased expression of minichromosome maintenance protein-2 (MCM2), a marker of cell proliferation (Stubbs et al. 2007). Increased recruitment of growing preantral follicles has been reported in the prenatally androgenised sheep, which therefore provides an important animal model for development of PCOS (Forsdike et al. 2007).

The aim of this study was to determine, using the prenatally androgenised sheep, whether increased initiation of follicle growth in PCOS can be attributed to an effect of excess androgen on granulosa cell proliferation.

Methods and results: We analysed the expression of MCM2 (by immunohistochemistry) in granulosa cells of ovarian sections from prenatally androgenised sheep (8 months old) and their respective controls. A total of 330 follicles (188 control and 142 androgenised) were examined. In prenatally androgenised adult female sheep there was a significant increase (compared with control ovaries) in the proportion of follicles that showed positive MCM2 labelling in granulosa cells at transitional (37%) and primary (78%) stages of follicular development (χ²=15.4, P<0.0001 and χ²=6.5, P<0.010, respectively).

Summary and conclusions: The increased expression of MCM-2 in early growing follicles in ovaries from prenatally androgenised sheep is indicative of increased granulosa cell proliferation. These findings resemble the observations in ovaries of women with PCOS and suggest that androgens may play a part in disordered early follicle development in PCOS.

References:
Stubbs S et al. JCEM 2007 92 4418.

Forsdike RA et al. J Endocrinol 2007 192 421.

Acknowledgements: CAPES - Brazilian Ministry of Education.