Objective: To explore the mechanism of the effect of cadmium exposure on TopBP1-induced mitochondrial DNA damage in atherosclerotic rats to affect oxidative stress.
Methods: 50 rats were established atherosclerotic model, and they were divided into model control group (MC group), low-dose cadmium exposure group (LD group), medium-dose cadmium exposure group (MD group), high-dose cadmium exposure group (HD group), and positive control group, with 10 rats in each group. Rats in the LD group, MD group, and HD group were intraperitoneally injected with different doses of cadmium acetate solution for intervention, rats in the PC group were intraperitoneally injected with oxidized banking solution, and those in the MC group were injected with normal saline. 10 rats were taken as the normal control group (NC group). Human umbilical vein endothelial cells were taken for cell experiments, normal saline was added as the blank control group (group A), cadmium acetate solution was added (group B), oxidized bankning solution was added (Group C), and oxidized bankning solution and cadmium acetate solution were added (Group D). Western blot and fluorescence quantitative PCR were used to detect the protein and mRNA expressions respectively. ROS, MDA, and SOD were detected by ELISA, apoptosis of endothelial cells was detected by flow cytometry, and arterial plaque damage was observed by oil red O staining.
Results: The relative expressions of TopBP, Bax, and Bcl-2 proteins in rat aortic tissues in each group were significantly different (all P < .05). The relative expressions of TopBP1 and Bcl-2 proteins in the aortic tissues of rats in NC group, MC group, LD group, MD group, HD group, and PC group decreased (all P < .05), while the relative expressions of Bax protein in those groups were increased (all P < .05). Similarly, the relative expression levels of Topbp1mRNA, BaxmRNA, and Bcl-2mRNA in the aortic tissues of rats in each group were significantly different (all P < .05). There were statistically significant differences in the expression levels of ROS, MDA, SOD, and mtDNA expression levels in the aortic tissues of rats in each group. There were statistically significant differences in TopBP1, Topbp1mRNA, and mtDNA among groups (all P < .05); while the relative expression of TopBP1 and Topbp1mRNA in groups A, B, C, and D decreased (all P < .05), the expression levels of mtDNA in those group increased (all P < .05), and the apoptosis rates of endothelial cells were also increased (all P < .05).
Conclusion: Cadmium exposure can down-regulate the expression of TopBP1 in atherosclerotic rats, aggravate mitochondrial DNA damage, promote oxidative stress response, and then induce the development of atherosclerosis.