Steroid hormones in peripheral blood plasma and androgen receptors in testis and epididymis of roe deer male (Capreolus capreolus) during the reproduction season

The roe deer (Capreolus capreolus) is a seasonally breeding species. The regression of the gonads and the inhibition of the process of spermatogenesis during the winter, the regeneration of the gonads during the spring and the occurrence of the highest level of spermatogenesis during the summer are observed in mature males. A radioimmunological analysis of the steroid hormone levels in the peripheral blood of male roe deer, measured at the beginning (May), at the peak (July/August) and at the end (September) of the reproductive season, demonstrated that the highest levels of progesterone, androstenedione, testosterone, and oestradiol coincided with the peak of reproductive activity. In addition, an immunohistochemical localisation of androgen receptors (AR) in the testis and epididymis during the same study periods showed that the highest immunoreactivity of the target cells occurred at the peak of the reproductive season (July/August). The results of the study indicate that all of the sex hormones (not only testosterone) may play a significant role in the regulation of reproductive processes. Increasing levels of steroid hormones (especially the androgens) induce the expression of androgen receptors in the target cells of the testis and epididymis, ensuring their normal function and maintenance.