The Role Of MAPK Cascade Pathway In Hepatic Ischemia Reperfusion Injury And Hepatic Ischemic Postconditioning In Rat

PartⅠThe Study of Protection Effect of Ischemic Postconditioning on hepatic ischemia reperfusion injury and hepatocyte apoptosis in ratsObjective:To establish the animal models of hepatic ischemia reperfusion and ischemic postconditioning and to study the effect of ischemic postconditioning on ischemia reperfusion injury and hepatocyte apoptosis in rats.Methods:The orthotopic partial hepatic ischemia reperfusion animal model was used.120 Wistar rats were divided into group ischemia reperfusion injury(IRI),group ischemic postconditioning(IPO) and group sham operation(SO).Specimens were harvested at 0,0.5,1,2, 4,8,12 and 24 hours respectively in group IRI and group IPO.Serum ALT and AST were detected by biochemery autoanalyzer,liver tissues were stained with hematoxylin and eosin(HE)for histologic study.Results:(1)In both IRI and IPO groups,the serum ALT and AST increased gradually with the reperfusion time extending.The peak was at 4 hour after reperfusion,then the level decreased gradually.(2) Compared with IRI group,the levels of ALT and AST in group IPO were lower significantly at 0.5h-8h(P＜0.05).,(3)Compared with the SO group,the MDA contents in hepatic tissues were increased significantly in both IRI group and IPO group(P＜0.01),while the SOD contents decreased significantly(P＜0.01).The MDA content in IPO group was lower than in the IRI group(P＜0.05),while the SOD content was higher than in the IRI group(P＜0.05).(4)The peak of the apoptosis index in IPO group and IRI group were at 1 hour after reperfusion.Compared with SO group,the apoptosis index were increased significantly in both IRI group and IPO group(P＜0.01),while the apoptosis index in IPO group was lower than in the IRI group(P＜0.05).(5)Hepatic necrosis and the inflammatory cells infiltration aggravated in IRI groups along with the reperfusion.Compared with IR group,IPO group showed less hepatocyte injury and smaller necrotic area in liver.Conclusion: Ischemic postconditioning before reperfusion could protect the rat liver against ischemia reperfusion injury.Conclusion:Ischemic postconditioning can protect hepatocytes from ischemia reperfusion injury in rats. PartⅡThe expression difference of MAPK cascade pathway between ischemia repeffusion injury and ischemic postconditioning in rats' liverObjective:Studying activation of different MAPKs(such as p38MAPK,p-ERK and p-JNK)expression in hepatic ischemia reperfusion injury and hepatic ischemic postconditioning settings,in order to explore their roles in hepatic ischemia reperfusion injury and protection in hepatic postconditioning.Methods:The orthotopic partial hepatic ischemia reperfusion injury animal model was used.120 Wistar rats were randomly divided into group ischemia reperfusion group(IRI),ischemic postconditioning (IPO)and group sham operation(SO).Liver tissues were harvested at 0. 0.5,1,2,4,8,12 and 24h after reperfusion in both IPO and IRI groups. The phosphorylated P38,JNK and ERK were detected by immunohistochemistry and half-quantitative analysis was made to study their expression changes in IRI and IPO groupsResults:(1)p-ERK increased slightly after ischemia and increased significantly at 30 minutes after reperfusion in IRI group and IPO group, the high level was kept until 4 hours after reperfusion,its peak time occurred at 2 hours after reperfusion.Compared with IRI group,the expression of p-ERK in IPO group were higher at 1 hour,2 hours and 4 hours after reperfusion(P＜0.05).(2)p-JNK increased slightly after ischemia and increased significantly at 30 minutes after reperfusion in IRI group and IPO group,the high level was kept until 4 hours after reperfusion,its peak time occurred at 2 hours after reperfusion. Compared with IRI group,the expression of p-JNK in IPO group were lower at 1 hour,2 hours and 4 hours after reperfusion(P＜0.05).(3) p-P38 increased slightly after ischemia and increased significantly at 30 minutes after reperfusion in IRI group and IPO group,its peak time occurred at 1 hour after reperfusion and began to decrease after 2 hours after reperfusion.Compared with IRI group,the expression of p-P38 in IPO group were higher after 1 hour after reperfusion(P＜0.05).Conclusion:The protection effect of IPO on ischemia reperfusion injury may have relationships with increasing the p-ERK and p-P38 MAPK expression and down-regulating the expression of p-JNK by IPO. The MAPK cascade pathway may play a very important role in ischemia reperfusion injury and the mechanisms of the protection effect of IPO. PartⅢThe impact of ischemic postconditioning on the immediate early gene c-fos and c-jun expressions in hepatocytes after ischemia reperfusion injury in ratsObjective:To investigate the expression of the immediate early gene c-fos and c-jun following the ischemia reperfusion injury(IRI)and the effects of the ischemic postconditioning(IPO)on the IRI in the rat livers.Methods:The orthotopic partial hepatic ischemia reperfusion injury animal model was used.120 Wistar rats were randomly divided into group ischemia reperfusion group(IRI),ischemic postconditioning (IPO)and group sham operation(SO).Liver tissues were harvested at 0. 0.5,1,2,4,8,12 and 24h after reperfusion in both IPO and IRI groups. The mRNA expressions of the immediate early gene c-fos and c-jun were detected with RT-PCR methods.Results:(1)The expression of c-fos and c-jun both kept a high level from 0.5 hour to 2 hours after reperfusion in IRI group.The peak time occurred at 1 hour after reperfusion.After 4 hours after reperfusion,the c-fos expression began to decrease gradually while the c-jun expression still kept high.(2)In every time point,the c-fos and c-jun expressions in IPO group were lower than IRI group(P＜0.05).(3)Compared with IRI group,the c-jun expression at 0.5 hour,1 hour and 2 hours after reperfusion in IPO group were significantly lower (P＜0.05).Conclusion:IPO can impact the immediate early gene expression at the very early moment after reperfusion,which may be part of the mechanisms of its protection effect on ischemia reperfusion injury.