The immunoexpression of androgen receptor, estrogen receptors alpha and beta, vanilloid type 1 receptor and cytochrome p450 aromatase in rats testis chronically treated with letrozole, an aromatase inhibitor.

The function of testis is under hormonal control and any disturbance of hormonal homeostasis can lead to morphological and physiological changes. Therefore the aim of the study was to investigate the expression of androgen and estrogen receptors (AR, ERs), vanilloid receptor (TRPV1), cytochrome P450 aromatase (P450arom), as well as apoptosis of cells in testis of adult rats chronically treated with letrozole (LT), a non-steroidal aromatase inhibitor, for 6 months. The testicular tissues were fixed in Bouin's fixative and embedded in paraffin. Immunohistochemistry with monoclonal antibodies (abs) against AR, ERa, P450arom, and polyclonalabs against ERβ, TRPV1, caspase-3 was applied. Long-lasting estradiol deficiency, as an effect of LT treatment, produced changes in the morphology of testis and altered the expression of the studied receptors in cells of the seminiferous tubules and rate of cell apoptosis. The immunostaining for AR was found in the nuclei of Sertoli cells and the cytoplasm of spermatogonia and spermatocytes in III-IV stages of the seminiferous epithelium cycle. The intensity of staining for P450arom was lower in the testis of LT-treated rats as compared to control animals. The immunofluorescence of ERα and ERβ was observed exclusively in the nuclei of Leydig cells of LT-treated rats. There were no changes in localization of TRPV1, however, the intensity of reaction was stronger in germ cells of the seminiferous epithelium after LT treatment. The apoptosis in both groups of animals was observed within the population of spermatocytes and spermatids in II and III stages of the seminiferous epithelium cycle. In testis of LT-treated rats the immunoexpression of caspase-3 was additionally found in the germ cells in I and IV stages, and Sertoli, myoid and Leydig cells. In conclusion, our results underline the important role of letrozole treatment in the proper function of male reproductive system, and additionally demonstrate that hormonal imbalance can produce the morphological abnormalities in testis.