Distribution of androgen receptor and steroid hormone concentrations in ovaries of immature bank voles: effect of photoperiod

Immunolocalisation of androgen receptor (AR) and steroid contents were analyzed in the ovaries of 7- and 14-day-old bank voles, reared in a long (LD) and short (SD) photoperiod. The strongest AR immunoreaction was found in the stromal cells, especially in the ovaries of 7-day-old animals, and in the granulosa cells of all types of ovarian follicles. Oocytes and the cells of surface epithelium were AR positive. The amount of ovarian androgens was relatively high, whereas the level of estradiol was negligible. This finding, and the presence of numerous ARs in various ovarian compartments, suggest that aromatization was very low during development and the primary function of androgens was hormonal action via a receptor-mediated pathway. Age- and photoperiod-related differences in ovarian progesterone (P₄) levels were higher in animals kept in LD than in SD, rising significantly on day 14. Androgen content tended to be lower in LD voles and slightly decreased on day 14. Photoperiod-related differences concerning AR immunolabeling were apparent only in 14-day-old animals. In LD, ovaries already possessed early antral follicles, showing strong AR immunolabeling in the cumulus cells. Immunoreaction of 3β-hydroxysteroid dehydrogenase (3β-HSD) showed that the primary interstitial and theca cells were the first to be active in ovarian steroidogenesis. In conclusion, AR is present in juvenile vole ovaries as early as day 7. The influence of the photoperiod on their number is observed beginning on day 14. Differences in steroid contents due to LD conditions occur in 7-day-old, and progresses in 14-day-old animals.