Effects of Cadmium on the Ultrastructure of Mice Sperm and Spermatogenic Cell and Gene Expression of bcl-2， bax in Male Mice

Abstract: The aim of the research is to study the effects of cadmium on the ultrastructure of mice sperm and spermatogenic cell and gene expression of bcl-2， bax in mice spermatogenic cell. Twenty-four male mice were divided into four groups. Three groups were treated with cadmium chloride by peritoneal injection using doses of 0.183 mg/kg， 0.915 mg/kg and 1.83 mg/kg respectively ， once per day and five times in total. One normal control group were treated with saline. After exposure of cadmium chloride for five days， the ultrastructure change of mice sperm and the nucleus and mitochondrion of spermatogenic cell was observed by the transmission electron microscope. The expression level of Bcl-2， Bax in spermatogenic cell was assayed by the immunohistochemical method. The electron microscope observation showed that sperm ultrastructure of 0.183 mg/kg group was not seen abnormal plasma membrane and mitochondrion and for 0.915 mg/kg group there was a bit more distant from plasma membrane to cytoplasm with some big vacuolisations in enlarged mitochondrial intracristal space， but there was no significant differences compared with control group (P>0.05). There was significant differences (P<0.05) between the 1.83 mg/kg group and control group for the sperm ultrastructure of plasma membrane and mitochondrial intracristal space. In three treated groups ， the abnormal rate for the ultrastructure of spermatogenic cell nucleus is much higher than that of the control (P<0.05)， more changes with concentrated cadmium. The rate of mitochondrial vacuolization is much higher in 1.83 mg/kg group than that of the control (P<0.05). The expression level of Bcl-2 and the ratio of Bcl-2 to Bax in three treated groups (0.183 mg/kg， 0.915 mg/kg， 1.83 mg/kg groups) were lower than that of control group (P<0.01) respectively. The expression level of Bax of 0.915 mg/kg group was higher than that of control group and 1.83 mg/kg group (P<0.01) respectively. The ratio of Bcl-2 to Bax in 0.915 mg/kg group was significantly lower than that in 1.83 mg/kg group (P<0.01). Taken together， we can propose that abnormal ultrastructure in sperm was induced by high dose cadmium. The abnormal ultrastructure and apoptosis in spermatogenic cell could be induced by low， middle or high dose cadmium. The change of expression level of Bcl-2， Bax induced by cadmium would be one of the possible mechanism for apoptosis in spermatogenic cell.

CSTR: 32200.14.cjcb.2006.03.0024