The Experimental Research Of Alpha-lipoic Acid Pretreatment On Hepatic Ischemia Reperfusion Injury In Rats

ObjectiveHepatic ischemia-reperfusion injury (HIRI) is a phenomenon that the blood flow restored after a period of time liver ischemia,but the injury aggravated.lt is a complicated process interacted by multiple factors,which occurred usually during hemorrhagic shock,liver serious trauma surgery,resection of liver tumors,liver transplantation and other clinical conditions.However,it is one of the important reasons which affected the prognosis of the diseases mentioned above.Nowadays the process of the occurrence and development of HIRI are still unknown exactly.lt involves many kinds of mechanisms.The previous studies showed that active oxygen, anaerobic metabolism and PH abnormal,calcium overload,microcirculation dysfunction, Kupffer cell and neutrophil activation and cytokines were important factors.Among them,active oxygen was produced abundantly during the process of blood flow restored after a period of time liver ischemia.lt could cause the structural and functional damage of liver via the mechanism of oxidative damage.Also active oxygen initiated the damage during the early stage and inflammatory responses during the follow-up times,which improved the occurrence and development of HIRI.In recent years how to prevent and treat HIRI has been the focus all the time home and abroad.The study of active prevention (pretreatment) has got great process,such as pharmacological preconditioning (PPC),ischemia preconditioning (IPC),heat shock preconditioning and ozone oxidative preconditioning (OzoneOP).This studied used the drugα-LA pretreating HIRI to do some associated experimental research.a-LA is vitamin,as the cofactor of two important enzymes,pyruvate Dehydrogenase and a-ketoglutarate dehydrogenase,it plays a role 大理学院硕士学位论文in the TAC.a-LA is metabolic antioxidants too, one of nature antioxidants which have the strongest effects till now.a-LA can regenerate the endogenous antioxidant,such as Vc,VE and GSH and a-LA itself.lt has highly effective oxidation.a-LA has been widely used to prevent and treat the diseases such as diabetes,degenerative diseases of brain and. nerve tissue,radiation damage and ischemia-reperfusion and other radical diseases.As the essential vitamin,a-LA could be soluble not only in water but also in fat. It has no functional or experimental toxic effect on human nor animals,so can be widely used in addition to its low price.Till now the effect of a-LA on HIRI in rats has not been reported.So we used the rat model of a-LA pretreating HIRI to investigate the protected effect and its mechanism.On one hand we can provide an efficient,safe and economical drug.On the other hand,we can develop a new approach of "new method of the previous drug-a-LA".This experiment we want to detect the change of ALT,AST,XOD and MDA activity and observe the pathological change of liver,to investigate the protected effect of a-LA on HIRI and its mechanism.Methods54 male SD rats were divided at random(1)sham-operated group(Sham group):The abdomen of rats was open,and the hepatoduodenal ligament was dissociated but not blocking hepatic blood flow;(2)alpha-lipoic acid pretreatment group(a-LA group):The succesive three days befor operation,to injectα-LA0.5ml (50mg/kg-d) into abdominal cavity,and injecting a-LA0.2ml (20 mg/kg) into sublingual vein just before ischemia and reperfusion;(3)ischemia reperfusion group(IR group):With the same group of a-LA, preoperative and intraoperatie injecting the same doses of saline.Using clamp method,the rats were used to be the model of the experiment of the 70 percent of hepatic ischemia reperfusion injury,and the hepatic blocking time was 40minutes.Ather2,4 and 6 hours of hepatic blood flow reperfusion,to detect the levels of ALT and AST in serum and the activity of XOD and MDA in hepatic tissue,and to observe hepatic tissue samples with the general method of hematoxylin-eosin staining. 大理学院硕士学位论文Results(1)he change of ALT and AST activity:The change of ALT and AST activity after 2,4,6 hours of ischemia-reperfusion almost had no difference,nor statistical significance in group Sham (P>0.05);While group IR had a little difference,but no statistical significance in group IR (P>0.05);But compared to group Sham,the activity of ALT and AST in group IR increased obviously at different times,it had dramatical difference and statistical significance(P＜0.01);The change of ALT and AST activity after 2,4,6 hours of ischemia-reperfusion had a little difference,but no statistical significance in group a-LA (P>0.05);But compared to group IR,the activity of ALT and AST in group a-LA decreased obviously at different times,it had dramatical difference and statistical significance(P<0.05).(2)The test result of XOD:As ischemia-reperfusion time changes,the activity of XOD was not statistically significant(P>0.05) in Sham group,in IR group and inα-LA group;Compared with group Sham,in IR group,the activity of XOD rised dramatically(P<0.01) after 2,4,6 hours of ischemia-reperfusion; While compared with group IR,inα-LA group,the activity of XOD dropped dramatically(P>0.05),and the difference was statistically significant(P<0.05).(3)The test result of MDA:As ischemia-reperfusion time changes,the activity of MDA was not statistically significant(P＞0.05) in IR group and inα-LA group;In IR group,with the extension of ischemia-reperfusion time,the MDA activity gradually increased(P<0.05) at different times,on the peak after 6h;Compared with group Sham,in IR group,the activity of MDA rised dramatically(P<0.01);While compared with group IR,in a-LA group,the activity of MDA dropped dramatically(P>0.05),and the difference was statistically significant(P<0.05).(4)Pathology change of liver tissue:Sham group were the normal liver tissue structures on each time point after ischemia-reperfusion;the hepatic cells were swelled,the sinusoid were narrowed,the large inflammatory cells infiltrated and patchy necrosis were observed through the pathological examination in IR group on each time point,which increasd significantly as extension time of ischemia-reperfusion;While compared with IR group,a-LA group had mild edema, 大理学院硕士学位论文necrosis was not obvious and a little inflammatory cells infiltrated.the hepatic histopathological changes were improved.Conclusion(1)α-LA has protected effect on HIRI.(2)The protected effect ofα—LA on HIRI may be related to its effect of antioxidating,clearing oxygen free radicals,reducing lipid peroxidation damage, stabling the liver cell membrane and so on.