Study On The Effect And Mechanism Of Metformin On Brain Injury In Sepsis

Objective:Brain injury caused by sepsis increases mortality and leads to cognitive impairment.There is still no effective treatment.In recent years,studies have shown that metformin has anti-inflammatory and cognitive functions,but whether metformin can improve sepsis-associated encephalopathy remains unclear.This study established a sepsis model by cecal ligation and puncture technique(CLP)to study the possible effects and mechanisms of metformin on sepsis-associated encephalopathy(SAE).Methods:1.The sepsis model was established by cecal ligation and puncture technique(CLP).The mice were randomly divided into 5 groups:Sham group,CLP group,CLP+Met group,CLP+vehicle group,CLP+Met+LY group;2.To clarify the protective effect of metformin,the survival rate,brain water content and blood-brain barrier permeability of mice were compared;3.The levels of serum interleukin-6(IL-6)、interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)in each group were determined by enzyme-libked immunosorbent assay(ELISA);4.The activity of superoxide dismutase(SOD)in serum and brain tissue of mice was determined by xanthine oxidase method,and the content of malonic dialdehyde(MDA)in serum and brain tissue of mice was determined by thiobarbituric acid method;5.The learning and memory abilities of mice were evaluated by morris water maze(MWM)test;6.Apoptosis of neurons in cerebral cortex,striatum and hippocampus was detected by TUNEL and immunofluorescence;7.The expression of p-protein kinase B(p-Akt)was detected by Western blotting.Results:1.By comparing the survival rate,we found that there was no death in Sham group,the survival rate of CLP group and CLP+ vehicle group decreased significantly,and the survival rate of CLP+Met group was significantly higher than that of CLP group(P<0,05);2.Compared with the Sham group,the brain water content and EB value of the CLP group and the CLP+vehicle group increased significantly.After administration of metformin,brain edema and EB value were reduced(P<0.05);3.Compared with the Sham group,the levels of IL-6,IL-1β and TNF-α in the CLP group and the CLP+vehicle group were significantly increased,and the administration of metformin reduced IL-6、IL-1β and TNF-α level in the serum of septic mice(P<0.05);4.Compared with Sham group,the MDA content in serum and brain tissue were increased,and SOD activity were decreased.After administration of metformin,the MDA content in serum and brain tissue were decreased,and SOD activity were increased(P<0.05);5.Compared with the Sham group,the CLP and CLP+vehicle mice had deereased navigation and space exploration ability.Metformin could increase the positioning cruise and space exploration ability of the poisoned mice.While compared with the CLP+Met group,the ability of positioning cruise and space exploration of the CLP+Met+LY group mice were decreased(P<0.05);6.Compared with the Sham group,the apoptotic rate of the cerebral cortex,striatum and hippocampal neurons in the CLP group and the CLP+vehicle group increased,and the administration of metformin improved the apoptosis of nerve cells in septic mice.The apoptosis rate of neurons in CLP+Met+LY group was higher than that in CLP+Met group(P<0.05);7.Compared with CLP group,the content of p-Akt in cerebral cortex of mice in CLP+Met group increased,while that in CLP＋Met+LY group decreased significantly compared with CLP＋Met group(P<0.05).Conclusion:1.Metfornin can improve the survival rate of septic mice,reduce brain edema,protect blood brain barrier,and improve cognitive function.2.Metformin can reduce the levels of IL-6,IL-1β and TNF-α in serum of mice with sepsis and improve oxidative stress.3.Metformin can reduce neuronal apoptosis in cerebral cortex,striatum and hippocampus caused by sepsis.4.Metformin can improves brain injury in sepsis via the PI3K/Akt signaling pathway.