Protective Effect And Mechanism Of Melatonin On Rat's Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI) mainly happens in shock,partialhepatectomy and liver transplantation, especially becomes one of major factors thatrestrict the therapeutic effect in liver transplantation . Melatonin (Mel) has alreadybecome hot spot for its transparent antioxidation and scavenging free radical. Toexprlore protective effect of Mel on Rat' s Hepatic Ischemia Reperfusion Injury , Melwas used as treatment in this investigation , samples were collected in different timeafter reperfusion, the enzyme levels in serum were examined: including alanineaminotransferase (ALT) , aspartate aminotransferase (AST) ,alkaline phosphatase(AKP); the expression of Caspase-3 were measured, anti-oxidase series superoxidedismutase (SOD), glutathione peroxidase (GSH-px) and terminal productions of lipidperoxidation (LPO) malondialdehyde (MDA) in liver tissue were determined.Meanwhile, hematoxylin-eosin (H.E) and immunohistochemical staining of theCaspase-3 were employed ;to observe the morphologic change under lightmicroscope as well as liver nuclei,cell organ and apoptosis under electron microscope,protective effects and Mechanism of Mel on Hepatic IRI was discussed in sub-cellularlevel.Materials and Methods(一),Materials72 healthy male Wistar rats (6-7 weeks old ) were randomly divided into threegroups: Mel exposured group (Mel), Alcohol solvent controlled group (Alc) and salinecontrolled group (NS). In accordance with Kobayashi, we occluded the left branches of portal vein, hepatic artery, hepatic duct for 45 min and then opened them to establishpartial hepatic ischemia-reperfusion injury models,which in left lobe and middle lobeof liver, then samples were collected in 3h, 6h, 12h, 24h after reperfusion respectively.The rats from Mel groups were intraperitoneally injected with Mel (20mg/kg) 30 minbefore experimentation. The duplicate concentration of alcohol and the same volume ofsaline were injected in control groups as substitution.(二),Methods(一) The enzyme levels in serum were examined: includingALT,AST,AKP by auto biochemical analyzer.(二) Anti-oxidase series: SOD, GSH. px and MDA were examinedin liver tissue.(三) Pathological examination of liver tissue.(四) Immunohistochemical staining of Caspase-3．(五) Observation the apoptosis of hepatic cells underelectron microscope.(六) Statistics: all the data was expressed as (?)±S. Statistics analysiswas performed with One-Way analysis of variation (ANOVA) and SNK test bysoftware SPSS 14．0．Results(一) Hepatic enzyme series in serum in rats:1,ALT The level of ALT in Mel group was significantly lower than that inthe Alc and NS group (P<0．05) .2,AST The level of AST in Mel group was significantly lower than that in theAlc and NS group (P<0．05) . 锘库槄3銆?AKP The level of AKP of Mel group measured in 6h, 12h, 24h wassignificantly lower than that of Alc and NS group (P<0．05) .鈽?浜? The level of anti-oxidase series and terminal productions oflipid peroxidationin (MDA ) in liver tissue.鈽?銆? SOD The level of SOD of Mel group measured in 3h, 12h, 24h wassignificantly higher than that of Alc and NS group (P<0．05) .鈽?銆? GSH.px The level of GSH.px in Mel group was significantly higher thanthat in the Alc and NS group (P<0．05) .鈽?銆?MDA The level of MDA in Mel group was significantly lower than that inthe Alc and NS group (P<0．05) .鈽?涓? Immunohistochemical straining of of Caspase-3 of liver tissue.鈽匱he expression of Caspase-3 in Mel group markedly lower than that in Alc andNS group (P<0．05) .鈽匱here were no significant differences between Ale and NS group among all theabove results.鈽?鍥? HE staining of liver tissue in rats鈽匱he extent of hepatic cell degeneration and necrosis,and the degree of destroy ofhepatic cord were more slighter in Mel group.鈽?浜? Observation of liver tissue under electron microscope in rats鈽匲niversal hepatic cell apoptosis were founded in controlled groups in 6h and 12h,and the more typical apoptotic phenomenon of advanced stage in 24h,which scarely canbe found in Mel group at the same time.鈽匔onclusions鈽匨el can protect liver from the ischemia-reperfusion injury by increasing activitiesof anti-oxidase series (SOD, GSH.px); decreasing the cumulation of MDA; inhibiting Caspase-3 expression in liver reperfusion tissue; alleviating the apoptosis of the hepaticcells.