Gonadotrophins and steroid hormones are vital in controlling the cyclical pattern of ovarian follicular development essential for fertility. Previous studies have shown that ArKO (aromatase knockout) female mice are infertile due to the absence of oestrogen, elevated levels of circulating gonadotrophins and testosterone and folliculogenic disruption. Therefore, the aim of this study was to determine the effects of E2 (oestradiol-17β) replacement, Acyline (GnRH antagonist) and Flutamide (anti-androgen) treatment on ArKO female mice. WT and ArKO female mice (C57B6/J129; 16 weeks old; n = 6–8/grp) were assigned into three main groups: group 1 - received either E2 (0.05 mg) pellet or placebo, group 2 - received either a single s.c. injection of acyline (1.5 mg/kg/week) or placebo and group 3 – received either flutamide (25 mg) pellet or placebo for 3 weeks. Mice were subjected to daily vaginal smears. The ovaries and uterine horns were collected and weighed. One ovary and the uterine horns were fixed in formalin for histological assessment, while the other ovary was snap frozen in Ultraspec solution for RNA isolation and gene expression studies. Serum was collected for hormone measurements. All female ArKO mice exhibited an abnormal cycle that alternated between diestrus and early oestrus. E2 replacement restored the oestrus cycle in ArKO female mice but acyline and flutamide treatment did not. Histologically, hemorrhagic cystic follicles were present in all placebo, acyline and flutamide treated ArKO ovaries, however, E2 replacement improved the ovarian and uterine phenotypes. E2 replacement and acyline treatment also led to a decrease in serum gonadotropin levels in ArKO mice. In summary, E2 replacement could reverse the abnormal reproductive phenotype of the ArKO female mice. This study suggests that the reproductive phenotype of the ArKO female mouse is due to the direct effect of oestrogen and not due to the elevated circulating levels of gonadotrophins and testosterone.
Supported by NH&MRC (Regkeys 241000, 338510 and 198705)
Prenatal androgen treatment does not alter the firing activity of hypothalamic arcuate kisspeptin neurons in female mice
