Study On Mitochondrial Energy Metabolism And Apoptosis In Mice After Combined Exposure To Cadmium And Mercury Based On The Levels Of Heavy Metals Found In The Urine Of Gold Miners

Objective:Both cadmium and mercury are highly toxic heavy metal elements,and professional mining workers are at risk for exposure to cadmium and mercury.Epidemiological survey results show that workers engaged in gold mining are exposed to cadmium and mercury,and higher levels of cadmium and mercury are detected in surrounding plants,soil and water;a large number of animal experimental studies have shown that the liver is its common target,and both can cause apoptosis.Studies have found that some substances in the mitochondria are closely related to apoptosis,such as reactive oxygen species?ROS?,cytochrome C?Cyt C?,and apoptosis-inducing factor?AIF?.Stimulated by apoptotic signals,mitochondrial permeability?MPT?conversion changes,which trigger a series of changes in??mMimtP?o,cT hPAo)I,n Fdr reialaen,ad si eno ctlohufe driC naygtp otChp,te o atoincpde fnraiencdtguo rcostif o rneml ietoaofs cehm oiatnondcdrhi aoBln cdplr eirfaaml memialbeyi mlictbhyra atnnrega ensps.io ttieAonfntt ieaprl o tr(he?es transmission of different stimulus signals is concentrated in the mitochondria,it activates or inhibits apoptosis-related signaling molecules in the mitochondria,and then regulates apoptosis through corresponding signal transmission pathways.Whether cadmium and mercury have synergistic effects on liver mitochondrial metabolism and apoptosis has not been reported.In order to do this,we used animal experiments of combined effects of cadmium and mercury to observe the effects of different exposure groups on mitochondrial metabolism and apoptosis in mice livers,and to preliminary explore whether cadmium and mercury would interact with mitochondria as the entry point.To provide evidence for clarifying the synergistic effect of cadmium and mercury on mitochondrial metabolism and apoptosis in mouse liver.Methods:This study collected urine from workers in gold mines and steel smelters,and detected a series of heavy metals in the urine such as creatinine,arsenic,and cadmium.Adult male?29±3g?Kunming mice were selected and randomly divided into four groups according to body weight.The control group was injected intraperitoneally with saline,the mercury group was intraperitoneally injected with 1mg/kg bw Hgcl2;the cadmium group was intraperitoneally injected with 1 mg/kg bw Cdcl₂;combined group intraperitoneal injection of 1 mg/kg bw Hgcl₂+1 mg/kg bw Cdcl₂ exposure 4 weeks.After the end of the exposure period,mice were measured for general indicators such as body weight,drinking water,and diet.The serum was measured for ALT content by ELISA method.Paraffin sections of the liver were stained with HE to observe the structure of liver lobules in mice;ELISA method to detect the activity of GK,CCO,NAD⁺-IDH,mitochondrial metabolism-related enzymes in mouse liver tissue;RT-PCR to detect the expression of mitochondrial apoptosis-related genes Caspase-3,Caspase-9,Bax mRNA;Immunoblot detection of each the expressions of Caspase-3 and Caspase-9 in mitochondrial apoptotic process of mice in the group.Results:1.Analysis of heavy metal exposure of gold miners:the content of cadmium and mercury in the urine of gold miners was higher than that of workers in steel smelters,the difference was statistically significant?P<0.05?,and the remaining metal content was not statistically different?P>0.05?.The excess rate of cadmium and mercury in the urine of miners was significantly higher than that of steel smelters,and the difference was statistically significant?P<0.05?.Therefore,gold miners may be exposed to occupational heavy metals such as cadmium and mercury.2.The effect of combined exposure of cadmium and mercury on general conditions of mice:until the fourth week of exposure,the weight of mice in each exposure group was significantly lower than that in the control group,and the difference was statistically significant?P<0.05?.Changes in drinking water of mice in each group,the average drinking water of mice exposed to cadmium and mercury combined exposure was significantly lower than that of the control group,and the difference was statistically significant?P<0.05?.There was no significant difference in the diet of mice compared with the control group.There was no significant difference in the liver coefficients of the mice compared with the control group.3.Effect of combined exposure of cadmium and mercury on serum ALT of mice:The serum ALT content of mice in each exposure group increased significantly,the difference was statistically significant?P<0.05?,and the increase was most significant in the combined group.The results showed that cadmium,mercury,and the combination of cadmium and mercury had no interaction on liver ALT levels in mice,only an additive effect.4.The effect of combined cadmium and mercury exposure on HE staining in mouse liver:HE staining was used to observe the morphology and structure of liver in mice.The liver lobes and central veins in the control group were intact and the liver cells were arranged reasonably.The morphology of the central vein in each exposure group had obvious vacuolar degeneration and inflammatory cell infiltration.5.Effects of combined exposure of cadmium and mercury on mitochondrial membrane potential of mouse liver:Compared with the control group,mitochondrial membrane potential of the combined exposure group was significantly reduced,and the difference was statistically significant?P<0.05?.The results of factorial analysis showed that cadmium combination with mercury showed a synergistic effect on the liver mitochondrial membrane potential.The simple effect showed whether the presence of cadmium affects the mitochondrial membrane potential of the mouse liver.Further analysis showed that the presence of cadmium and mercury has a greater effect on the mitochondrial membrane potential of the mouse liver.6.Effects of combined exposure of cadmium and mercury on mitochondrial metabolism-related enzymes in mouse liver:The results of measurement of hepatokinase activity in mouse liver showed that compared with the control group,the average value of enzyme activity in each group was significantly lower than that in the control group.It was statistically significant?P<0.05?,and the mean of the combined exposure group was significantly lower than the other groups.Factorial analysis showed that the combination of cadmium and mercury had no interaction on liver GK levels in mice,only an additive effect.The liver NAD⁺-IDH activity measurement results were the same as GK.There was no significant difference in CCO content.7.Effect of cadmium and mercury combined exposure on mitochondrial-mediated apoptosis in mouse liver:the combined group showed additive effects on mouse liver Caspase-3 and Bax m RNA.It showed synergistic effects on Caspase-9 m RNA,Caspase-3,and Caspase-9 proteins.The simple effect of the expression of Caspase-3 protein showed that the presence of mercury contributes a great deal to it,while the presence of Caspase-9 mRNA and Caspase-9 protein were both cadmium and mercury,which also had a great effect on it.Conclusion:1.Miners in gold mining were exposed to cadmium and mercury.2.Cadmium and mercury exposure could cause liver damage in mice.3.Cadmium and mercury had a synergistic effect on mitochondrial membrane potential in the liver of mice.4.Cadmium and mercury had synergistic effects on the expression of Caspase-9mRNA,Caspase-3,and Caspase-9 protein in mouse liver.