Immunohistochemical study of flotillin-1 in the rat testis during postnatal development

The level and cellular localization of fotillin-1, a lipid raft protein, was examined in the testis of rats during postnatal development and spermatogenesis in order to determine if flotillin-1 is involved in testicular development. The testes of rats were sampled on postnatal days 7, 14, 21, 40, and 60, and analyzed by Western blot and immunohistochemistry. Western blot analysis detected flotillin-1 in the testes at days 7 and 14 after birth but the level decreased significantly at postnatal days 21, 40 and 60. At postnatal days 7, 14, 21, and 40, flotillin-1 immunolocalization was observed mainly in the Sertoli cells. However, there was little flotillin-1 immunolabeling in the spermatogenic cells from the seminiferous tubule of the testes. In the seminiferous tubule of the testes at postnatal day 60, flotillin-1 immunoreactivity in the Sertoli cells varied according to the stages of the spermatogenic cycle; intense immunoreactivity being observed in stages IX-III and less in stages IV-VIII. These results suggest that flotillin-1 participates in the developmental process of Sertoli cells and is involved in the regulation of spermatogenesis.