Photoperiod-dependent capability of androgen aromatization and the role of estrogens in the bank vole testis visualized by means of immunohistochemistry.

Detection of steroid hormone receptors within a target tissue is important for an understanding of their crucial role in regulating of steroids' action. In the light of recent knowledge on the role of estrogens in male gonads the efforts were undertaken to clarify and discuss a role of androgen receptors, aromatase and estrogen receptors (ER) in mediating testosterone and/or estradiol action in testicular cells of bank voles that were kept under short or long light cycles. Immunohistochemistry was performed on paraplast embedded sections of the bank vole testes. First, androgen receptors were immunolocalized in testicular somatic cells while germ cell did not express any immunoreaction. Moreover, the ability to convert androgens to estrogens by various testicular cells was documented; aromatase immunoexpression was found in testis sections, not only in Leydig cells and Sertoli cells but also in germ cells. Finally, the expression of estrogen receptor-alpha (ERalpha) was observed in Leydig cells whereas the presence of estrogen receptor-beta (ERbeta) was detected in Sertoli and germ cells, namely spermatocytes and spermatids. The cellular distribution of androgen receptors appeared to be light -and age-dependent in adults; immunoexpression of aromatase and ERbeta was found to be both age -and photoperiod-dependent in germ cells.

Immunohistochemical localization of estrogen receptors in the ovine corpus luteum throughout the estrous cycle.

Using immunohistochemistry and Western blot analysis we attempted to identify the estrogen receptors in ovine luteal cells at different stages of the estrous cycle. Monoclonal antibody against estrogen receptors was used for immunolocalization of estrogen receptor-alpha in corpora lutea sections. Generally, the most intense cytoplasm staining was present in large luteal cells. On the 6th day of the estrous cycle, weak immunostaining of estrogen receptors was observed in large luteal cells as well as in the connective tissue. Luteal cells from regressing corpora lutea expressed the weakest immunostaining. The most intense immunoreactivity for estrogen receptors was found in sections of corpora lutea collected on the 9th day of the cycle. Both, cytoplasmic and nuclear localization was observed depending on cell types in the ovine corpus luteum. Our studies demonstrated the presence of the estrogen receptor-alpha in the luteal cells and suggested an autocrine/paracrine role of estrogen in the regulation of estrous cycle in sheep.

Localization of cytochrome P450 aromatase and estrogen receptors alpha and beta in testicular cells--an immunohistochemical study of the bank vole.

Age- and light-dark cycle-induced changes in immunoexpression of aromatase and estrogen receptors alpha and beta were studied in testes of a seasonally breeding rodent, the bank vole. Seasonal breeding can be mimicked by exposure to different light cycle regimes. In testes of animals that were exposed to long light cycles of 18 h light and 6 h darkness aromatase was in Leydig cells and seminiferous tubules, mainly in spermatocytes, whereas in animals exposed to short light cycles (6 h light and 18 h darkness), only Leydig cells exhibited positive immunostaining for aromatase. Whatever the age of animals, immunostaining for estrogen receptor alpha was restricted to Leydig cells, whereas estrogen receptor beta immunoreactivity was mainly confined to Sertoli cells of both of immature and adult animals, independently of the regimes of light. Additionally, in testes of animals that were exposed to long light cycles, estrogen receptor beta immunoreactivity was observed in seminiferous tubules. Nuclei of germ cells, predominantly spermatocytes and elongated spermatids, were strongly positive which correlated well with aromatase immunoreactivity. As far as we know, the present study is the first study that describes immunoexpression of aromatase and both estrogen receptors alpha and beta in testis of the bank vole. We provide strong evidence that estrogens are not only produced in Leydig cells but also in germ cells in this rodent. These female hormones may play a physiological role in testis, likely in the development of germ cells during spermatogenesis.

Immunolocalization of androgen receptors in testicular cells during postnatal development of the bank vole (Clethrionomys glareolus, S.).

Determination of the cellular distribution of the androgen receptors within the testis is of great importance for an understanding of their essential role in mediating of androgen action in the male gonad. In bank voles, which are seasonally breeding rodents, photoperiod is one of the most important factors inducing profound changes in the morphology and hormonal activity of the testes. Immunolocalization of androgen receptors was found in all somatic cells such as Sertoli cells, Leydig cells, and peritubular-myoid cells, however, distribution of the androgen receptors in various cell types depended on age of animals. Intensity of immunoreactivity was noticed as age and photoperiod-dependent. Males reared under different light regimes showed a significant correlation between the length of light and sexual maturation. Therefore, morphology of the testis from young and adult bank voles was also presented.