Effect Of M-TOR Signaling Pathway On Liver And Brain Injury In C57 Mice Caused By Chronic Manganese Exposure

Objective:To establish the model of liver and brain injury induced by chronic manganese exposure,to explore the relationship between autophagy and liver and brain injury,and the regulatory role and significance of m-TOR signaling pathway,so as to provide theoretical basis for the prevention and treatment of manganese poisoning.Methods:C57 mice were used to establish a chronic manganese exposure model,and the autophagy inhibitor 3-Methyladenine(3-MA)was used to intervene.After the modeling,the behavioral changes of the mice were detected by behavioral methods;Blood manganese of mice in each group was detected by atomic absorption spectrophotometer;Serum ALT and AST levels of mice in each group were detected by full-automatic biochemical analysis;Liver morphology of mice in several groups was observed by HE staining;Transmission electron microscopy was used to observe the changes of liver cell,striatum and substantia nigra in each group and the changes of autophagolysosome;The apoptosis level of hepatocytes was evaluated by TUNEL staining;The expression of autophagy related proteins LC3-II,Beclin1 and m-TOR signaling pathway was detected by Western blot.Results:1.The results of animal experiments show that manganese can induce the increase of autophagy in the liver of the mouse and lead to liver damage,and this process is accompanied by the dephosphorylation of m-TOR and its downstream protein p70S6K;2.Compared with manganese exposure alone,3-MA could reduce the levels of ALT and AST in liver(P< 0.05);3.HE staining and TUNEL staining showed that there were more inflammatory cell infiltration in the hepatocyte space of the manganese exposed group,the number of liver binuclear cells increased and the number of liver cell apoptosis increased significantly.After 3-MA intervention,the effect of manganese exposure on liver inflammatory infiltration and injury was reduced,and the number of liver cell apoptosis was reduced compared with the manganese exposure group(P< 0.05);4.The results of the pole climbing experiment showed that compared with the manganese exposure alone,the time from the top to the head down and the time from the head down to the platform at the bottom of the pole were prolonged after C57 mice were exposed to manganese and combined with 3-MA(P< 0.05);5.Transmission electron microscopy observations showed that after exposure to manganese,there was obvious mitochondrial damage in the hepatocytes,striatum,and substantia nigra of mice.After combined with 3-MA intervention,mitochondrial vacuolation was reduced and the number of autophagolysosomes was reduced;6.Western blot analysis found that in the hepatocytes,the combination of manganese exposure and 3-MA intervention group compared with the manganese exposure group,LC3-II,Beclin1 autophagy-related protein decreased,m-TOR,p70S6 K levels increased,there was a statistical difference(P <0.05).Conclusions:1.Chronic manganese exposure can induce liver cell and tissue damage in C57 mice.In addition,manganese may induce an increase in hepatocyte autophagy by inhibiting the m-TOR signaling pathway;2.Inhibition of autophagy can alleviate liver cell or tissue damage induced by chronic manganese exposure,and the level of dephosphorylation of the m-TOR pathway is reversed,suggesting that excessive autophagy guided by the m-TOR pathway may have certain promotion effect;3.Inhibition of cell autophagy can enhance striatum and substantia nigra tissue damage induced by chronic manganese exposure,suggesting that autophagy has a certain protective effect in the process of manganese-induced neuronal damage.