Effects Of Manganese Exposure On Iron And Manganese Metabolism In Hemochromatosis Mice

ObjectivesBased on the characteristics of iron accumulation in multiple organs and manganese ion reduction in patients with hemochromatosis,this study aimed to provide a new theoretical breakthrough for further understanding the role of ion homeostasis regulation in the course of hemochromatosis from the perspective of possible competition in iron and manganese transport.MethodsThis study was divided into acute and subchronic manganese exposure experiments.Thirteen weeks of male Hfe-/-mice in acute experiment were randomly divided into control group and manganese exposure group,intraperitoneal injections of 0.9%saline and 400 mg/kg body weight(BW)of manganese chloride were administered,respectively.Subsequently,phenotypic observation and testing of iron and manganese metabolism related genes expression were carried out.Thirteen weeks of Hfe-/-mice in subchronic experiment were randomly divided into male and female control groups,male and female manganese exposure groups,and given daily intraperitoneal injection of 0.9%saline and 40 mg/kg BW of manganese chloride,respectively,for four weeks.The body weight and food intake of the mice were measured during this period.After manganese exposure,blood biochemical examination was performed,non-heme iron and manganese levels were detected,and the expression of iron and manganese metabolism-related genes were detected by RT-PCR.Results1.Compared with the control mice,the non-heme iron in the liver of Hfe-/-mice was elevated,and serum iron was also elevated(P<0.01).While the body weight of mice in both groups had nonsignificant difference,the level of blood manganese in Hfe-/-mice had a tendency to reduce(P>0.05).2.In the acute manganese exposure experiment,the mice in control group could eat,drink and move freely,with good mental states.One of the mice in the manganese exposure group died about 8 hours after the injection,while the rest of the mice were in bad mental states,curled up and motionless,shaggy and dying.RT-PCR results showed that compared with the control group,the expression of Zip8 in liver of mice in the manganese exposure group was down-regulated significantly(P<0.01),while the expressions of Zip14 and Znt10 were up-regulated significantly(P<0.05).The expression of Fpn was down-regulated significantly(P<0.01).3.The general indicators of Hfe-/-mice in subchronic manganese exposure experiment:Compared with the control group,the male mice in manganese exposure group had lower body weight at 15 and 16 weeks old(P<0.01),while the body weight of female mice in manganese exposure group had nonsignificant difference at each time point(P>0.05).There was no difference in dietary intake between the manganese exposure group and the control group(P>0.05).Compared with the control group,the white blood cell count of mice in manganese exposure group was decreased significantly(P<0.01).Both the platelet count and the thrombocytocrit were increased significantly in female mice in manganese exposure group(P<0.01).4.The iron indexes of Hfe-/-mice in subchronic manganese exposure experiment:Compared with the control group,female mice in manganese exposure group showed a significant increase in serum iron and serum total iron binding capacity(P<0.05),the difference in both groups of male mice was not significant(P>0.05).Compared with the control group,the non-heme iron in the brain of mice in manganese exposure group was increased(P<0.05),and the non-heme iron in the lung of female mice in manganese exposure group was increased(P<0.05),the non-heme iron in other organs did not change significantly(P>0.05).5.The level of metals in the liver of Hfe-/-mice in subchronic manganese exposure experiment:Compared with control group,the level of manganese in the liver of mice in manganese exposure group was increased(P<0.05),the level of iron,zinc and copper did not change significantly(P>0.05).6.RT-PCR results of Hfe-/-mice in subchronic manganese exposure experiment:Compared with the control group,the expression of Zip14 was down-regulated and the expression of Hamp was up-regulated in male group(P<0.05),the expression of the other genes related to iron metabolism and manganese transport in the manganese exposure group did not change significantly(P>0.05).ConclusionHfe-/-mice has iron accumulation in the body,high dose manganese exposure can cause a lethal phenotype.Subchronic manganese exposure does not reduce iron accumulation in Hfe-/-mice,while,the results of male mice suggest that Zip 14 in the liver may be a target for the interaction of manganese and iron,subsequent experiments can reduce manganese exposure dose,properly set the gradient of manganese exposure to explore appropriate concentrations of manganese exposure that can reduce the level of iron.