Localization of cytochrome P450 aromatase and estrogen receptors alpha andbeta 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 seasonall y breeding rodent, the bank vole. Seasonal breeding can be mimicked by expo sure to different light cycle regimes. In testes of animals that were expos ed to long light cycles of 18 h light and 6 h darkness aromatase was in Ley dig cells and seminiferous tubules, mainly in spermatocytes, whereas in ani mals exposed to short light cycles (6 h light and 18 h darkness), only Leyd ig cells exhibited positive immunostaining for aromatase, Whatever the age of animals, immunostaining for estrogen receptor alpha was restricted to Le ydig cells, whereas estrogen receptor beta immunoreactivity was mainly conf ined to Sertoli cells of both of immature and adult animals, independently of the regimes of light. Additionally, in testes of animals that were expos ed to long light cycles, estrogen receptor beta immunoreactivity was observ ed in seminiferous tubules. Nuclei of germ cells, predominantly spermatocyt es and elongated spermatids, were strongly positive which correlated well w ith 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 evi dence 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.