Targeted Loss of Androgen Receptor Signaling in Murine Granulosa Cells of Preantral and Antral Follicles Causes Female Subfertility¹

Kirsty A. Walters ², Linda J. Middleton, Shai R. Joseph, Rasmani Hazra, Mark Jimenez, Ulla Simanainen, Charles M. Allan, and David J. Handelsman

ANZAC Research Institute, Department of Andrology, Concord Hospital, University of Sydney, Sydney, New South Wales, Australia

ABSTRACT Back to Top

Abstract: Ovarian granulosa cells display strong androgen receptor (AR) expression, suggesting a functional role for direct AR-mediated actions within developing mammalian follicles. By crossing AR-floxed and anti-Müllerian hormone (AMH)-Cre recombinase mice, we generated granulosa cell-specific androgen receptor knockout mice (GCARKO). Cre expression, assessed by lacZ activity, localized to 70%–100% of granulosa cells in most preantral to antral follicles, allowing for selected evaluation of granulosa cell AR-dependent actions during follicle development. Relative to wild-type (WT) females, GCARKO females were subfertile, producing a 24% reduction in the number of litters (P < 0.05) over 6 mo and an age-dependent decrease in total number of pups born, evident from 6 mo of age (P < 0.05). Follicle dynamics were altered in GCARKO ovaries at 3 mo of age, with a significant reduction in large preantral and small antral follicle numbers compared to WT ovaries (P < 0.05). Global premature follicle depletion was not observed, but increased follicular atresia was evident in GCARKO ovaries at 6 mo of age, with an 81% increase in unhealthy follicles and zona pellucida remnants (P < 0.01). Cumulus cell expansion was decreased (P < 0.01) and oocyte viability was diminished in GCARKO females, with a significant reduction in the percentage of oocytes fertilized after natural mating and, thus, in the rate of progression to the two-cell embryo stage (P < 0.05). In addition, compared with age-matched WT females, 6-mo-old GCARKO females exhibited significantly prolonged estrous cycles (P 0.05), suggesting altered hypothalamic-pituitary-gonadal feedback signaling. In conclusion, our findings revealed that selective loss of granulosa cell AR actions during preantral and antral stages of development leads to a premature reduction in female fecundity through reduced follicle health and oocyte viability.

Key Words: androgen receptor • female reproduction • granulosa cell • ovarian function

FOOTNOTES Back to Top

² Correspondence: Kirsty A. Walters, Andrology Lab, ANZAC Research Institute, Sydney, NSW 2139, Australia. E-mail: kwalters{at}anzac.edu.au