Research On The Autophagy Mechanism Of Rapamycin In Hepatic Ischemia Reperfusion Injury

Objective:In order to investigate the effect of mTORC1-ULK1 signaling pathway on autophagy in hepatic ischemia reperfusion injury in rats.Methods:Establish four groups of liver ischemia-reperfusion injury in rats,model of group A?low dose group?:preoperative intraperitoneal injection of 3 days of rapamycin?1.5 mg/kg/day?+ischemia 30 minutes;Group B?high dose group?:preoperative intraperitoneal injection of 3 days of rapamycin?2.0 mg/kg/day?+ischemia 30 minutes;Group C?control group?:preoperative intraperitoneal injection of 0.9%sodium chloride solution 3 days?1.5 ml/kg/day?+ischemia 30 minutes;Group D?normal group?:sham-operatedgroup.Thesamplesweretakenat24and72hoursafter surgery,respectively.Detection of serum:concentrations of ALT,AST,TNF-?and IL-6 were detected.Detection of liver tissue:mRNA contents of mTOR,S6K1,ULK1 and LC3 were detected by Quantitative Real-time PCR and Histopathology;Protein contents of ULK1,LC3,mTOR^ser2448,S6K1^thr378,ULK1^ser757er757 were detected by Western Bloting.Results:1.Results of pathological examination:liver pathological injury of group A and group B was less than that of group C,while liver pathological damage of group A was more than that of group B and liver pathological injury was less at 72 hours after surgery than that at 24 hours.2.Results of serum test showed that the serum concentration of ALT,AST,TNF-?,and IL-6 in groups A,B,and C were all higher than those in group D at 24hours after surgery,while those in group A and B were lower than those in group C,and those in group A were higher than those in group B,the difference was statistically significant?P<0.05?.Serum concentrations of ALT,AST,TNF-?and IL-6 were lower in each group at 72 h after surgery than that at 24 h after surgery.2.Q-PCR and WB results of liver tissue showed that the contents of ULK1 and LC3 mRNA,ULK1 and LC3 protein increased after 24 hours of liver ischemia reperfusion injury,and those contents increased with the increase of rapamycin dosage.The protein levels of mTOR,S6K1,mRNA,mTOR^ser2448,S6K1^thr378,ULK1^ser757decreased,and decreased with the increase of rapamycin dosage,Contents of protein of ULK1,LC3,and mRNA were lower at 72 h than that at 24h after surgery,while levels of mTOR and S6K1,mRNA and protein contents ofmTOR^ser2448,S6K1^thr378,ULK1^ser757were increased.Conclusion:Rapamycin can activate autophagy to protect liver function in hepatic ischemia reperfusion injury through activation mTORC1-ULK1 signaling pathway,and the protective effect of high-dose group on hepatic ischemia reperfusion injury was better than that of low-dose group.