[Location studies of Smad4 protein in the rat testis during postnatal development].

In order to shed light on the mechanisms of TGF-beta action in the testis,we examined the expression and function of Smad4 protein, the common-mediator Smads, which is one of intracellular signaling molecules of TGF-beta superfamily members, in rat testis during postnatal development. Whole testes were collected from SD rats aged 3 days, 7 days, 14 days and 28 days, and adult. In this study, we examined, by means of western blots, the protein expression of Smad4 during rat testicular development and its cellular localization by immunohistochemical ABC method with glucose oxidase-DAB-nickel enhancement technique. The results showed that the protein of Smad4 was present in rats from 3 days of age to adulthood, and the immunoreactivity for Smad4 was exclusively localized to the cytoplasm of Leydig cells with negative nuclei in the interstitial tissue at any time point. No expression was detected in germ cells. Therefore, our data provide evidence for the molecular mechanism of TGF-beta action in rat testes during postnatal development and spermatogenesis of rats.