Distribution of vitamin D receptor and 1α-hydroxylase in male mouse reproductive tract

Vitamin D has been introduced as one of the main regulators of spermatogenesis. Here, for the first time, we evaluated the expression of vitamin D receptor (VDR) and 1α-hydroxylase in all organs of male mice reproductive tract by immunohistochemistry and Western blotting. Epithelial cells of epididymis, seminal vesicle, coagulating gland, ductus deferens, preputial gland, and prostate were the prominent cell types that concomitantly expressed VDR and 1α-hydroxylase. Nearly all cell types in testis expressed both proteins. Interestingly, VDR intensity in epididymis epithelial cells was reduced toward cauda, in which only strong staining of stereocilia was observed. Although been positive in caput epididymis, sperms lost their VDR expression in cauda region. In all organs, sperms failed to express 1α-hydroxylase. Specific bands of the VDR and 1α-hydroxylase were determined in all tissues, except testis in which novel unprecedented isoforms of 1α-hydroxylase were observed. Our findings could provide further convincing evidence of pivotal role of this hormone in male reproductive biology.