Identification of differentially expressed SMADs in the testis of adenine-induced male infertile rats

The role of TGF-beta is critical in testis development and spermatogenesis. However, it remains unclear what is the function of SMADs (drosophila mothers against decapentaplegic proteins), as the intracellular mediators of AQ1 TGF-beta signaling, in dyszoospermia. Adenine-modeled infertile rats were used to detect the cellular localization and the expression levels of SMAD1, SMAD2 and SMAD4. SMAD1 and SMAD2 were mainly present in the cytoplasm of spermatogenic cells and SMAD2 was also present in the cytoplasm of Sertoli cells, but SMAD4 was exclusively present in the cytoplasm of Leydig cells and no expression was detected in the germ cells. Compared with a normal control group, the expression level of SMAD1 decreased significantly (p < 0.05), but the expression level of SMAD2 and SMAD4 increased significantly (p < 0.05). The serum level of testosterone (T) and sperm number decreased significantly (p < 0.05), while the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) level increased remarkably (p < 0.05) in the adenine-modeled group. Our study indicates that the dyszoospermia of male infertility rats results in changes of the SMAD expression level which affects the content of T, FSH and LH for spermatogenesis. The present data provide possible evidence for the regulatory role of SMAD during spermatogenesis of male infertility.