Effects Of Cadmium Exposure On Gonadal Tissue And Gene Methylation In Rats

To investigate the effects of cadmium on methylation of Bcl-2 and Caspase-9 genes in gonad of SD rats,one hundred and four healthy clean SD male rats were randomly divided into A,B,C and D groups,each group consisted of 26 rats.In the control group,saline was injected intraperitoneally every day,Three experimental groups were injected intraperitoneally with 0?0.3?0.6 and 1.2 mg/kg Cd Cl2 solution per day,respectively.During the observation,recording the activities of rats and weight changes,after 28 days of feeding,the gonad,liver,muscle and kidney tissues were taken.The contents of cadmium,SOD,CAT,GPX activity and MDA content were measured,Pathological sections of the gonadal and hepatic tissues were obtained and stained with HE.The expression of bcl-2 and caspase-9 m RNA in the tissues of rats were detected by real-time quantitative RT-PCR.The changes of methylation of Bcl-2 and Caspase-9 genes in gonadal tissue were detected by MSP.Methylation of CPG island of Bcl-2 and Caspase-9 was detected by Mass Array methylation.Statistical analysis was performed using one-way ANOVA and chi-square test.result: 1,the weight of rats in test group was slower than that of control group,and there was significant difference.2.the amount of cadmium in the gonad and liver of the experimental group was significantly higher than that of the control group,with significant difference.3.Compared with the control group,the contents of MDA,GPX,SOD,CAT in different tissues of the experimental group increased at first and then decreased,with the increase of cadmium dose.The difference was significant or very significant in the control group.4.Histopathological examination showed that the liver and gonadal tissues of the experimental group showed different degrees of injury.5.The methylation level of bcl-2 gene was significantly increased by the concentration of cadmium,and the quantitative expression of bcl-2 gene was significantly decreased.The methylation level of caspase-9 gene was not significantly affected by cadmium concentration,but it was higher than that of control group,andthe quantitative expression of caspase-9 gene was significantly increased with the increase of cadmium concentration.In conclusion: 1.Cadmium-induced rat model was successfully established on the basis of body weight,cadmium content,biopsy,and antioxidant enzyme activity,and could be used as a good model for studying DNA methylation.2.Cadmium induces the hypermethylation of Bcl-2 gene promoter region,inhibits the expression of this gene in rat gonadal tissue,leading to imbalance of apoptosis and proliferation.The level of methylation of caspase-9 promoter was lower than that of bcl-2 gene,and the expression of caspase-9 m RNA was increased by cadmium stimulation,which further promoted the progress of apoptosis.