Effects Of Nickel Sulfate(NiSO₄) On Apoptosis And Expression Of Bcl-2 And Bax In Spermatogenic Cells Of Male Rats

Objective To explore the effects of nickel sulfate(NiSO₄) on apoptosis of spermatogenic cells in rats and its possible mechanism for providing the theoretical evidence of preventing and curing of male reproductive toxicity.Methods The male Wistar rats with sexual maturation were divided into four groups randomly, and three groups of rats were administrated intraperitoneally with nickel sulfate daily at doses of 1.0, 2.0, 4.0mg/kg body weight respectively for 30 days, but the control group was administrated with normal saline in same volume according to the rats' weight. Flow cytometry(FCM), the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling(TUNEL) and transmission electron microscope were used to detect apoptosis of spermatogenic cells.Immunohistochemical method was used to detect the expression of Bcl-2 and Bax in spermatogenic cells. The serum estradiol level was measured by radioimmunoassay. The testis homogenates were prepared to measure the content of lipid peroxidation(LPO) and activities of total antioxide capacity(T-AOC), anti-reactive oxygen species(anti-ROS), glutathione perioxidase(GSH-Px) using spectrophotometric assay.Results (1) The apoptotic ratio of testicular spermatogenic cells detected by FCM were higher than that of control group(p<0.05) and the number of apoptotic spermatogenic cells detected by TUNEL were increased significantly in 2.0,4.0mg/kg NiSO₄ groups(p<0.01).The apoptotic cells were mostly spermagonia and spermatocytes at the earlier stage and advanced stage of spermatogenesis.The morphological changes of apoptosis were observed obviously by transmission electron microscope. (2) Compared with the control group, the Bcl-2 expression were downregulated while Bax expression were upregulated significantly at the earlier stage and advanced stage of spermatogenesis in 2.0, 4.0mg/kg NiSO4 groups (p＜0.05), however the serum estradiol level decreased in 2.0, 4.0mg/kg NiSO₄ groups(p＜0.01). (3) The LPO content in testis of 2.0, 4.0mg/kg NiSO₄ groups were increased, but the activities of anti-ROS, GSH-Px and T-AOC were inhabited in 2.0, 4.0mg/kg NiSO₄ groups.Conclusion The results demonstrate that apoptosis plays an important role in the rat testicular toxicity induced by NiSO₄ and spermatogenia and spermatocytes may be as possible as its target cells. The mechanism of spermatogenic cell apoptosis may be associated with the changes of serum estradiol level, Bcl-2 and Bax expression and oxidative stress caused by nickel sulfate.