胃饲乙醇预处理诱导增强肝脏对缺血—再灌流的耐受性

Hepatic ischemia/reperfusion injury is a common problem encountered in many clinical conditions . It affects directly on the outcome of the patients. Although many studies have been done in this field, it still remains an unsolved problem..More and more evidence indicate that preconditioning, such as ischemia and heat shock, could protect liver against I/R injuries. But these methods are less likely to be applied in clinic because of their extensive damages to the body. So it is necessary to find out a new way of preconditioning on the liver..It is shown that heat shock protein 70s can be induced in several tissues and organs by low dose of ethanol exposure which lead will lead to more protective effect from cell injuries. In addition, ethanol preconditioning(EPC) is more convenient and acceptable for clinical use. Ethanol exposure can take effect in many ways for preconditioning, such as ischemia, endotoxin preconditioning. It is thought to elicit several preconditioning-like protection of the liver.Based on these investigations, this study aims to explore the induction of ischemia/reperfusion bearance of the rat liver by ethanol preconditioning and the related mechanisms.Methods and Results.1. Establishment of the ethanol-preconditioning protocol.Hepatic inflow occlusion under portal vein blood bypass mode was adopted in this study. Adult male Wistar rats were randomly divided into:normal control group(N); ethanol group(E):gastric gavage with a single dose of 40%,5 g/kg; ischemia-reperfusion group(IR):rats were subjected to ischemia for 90 min; and ethanol preconditioning group(EPC):rats were subjected to hepatic ischemia prior to a single dose of 40%,5 g/kg.bw of ethanol for 90 min . The mortality, pathological changes of the liver, activities of serum ALT and AST, were determined. Furthermore, based on the alcohol concentration, dose, chance of ethanol gavage, L27（313）orthogonal experiment was designed to optimize the protocol of ethanol preconditioning. Results ⑴ A slight symptom was observed in the rat after ethanol gavage. No rats died in the experiment. ⑵ No significant difference of ALT was observed between ethanol group and normal group; Compared with nomal control group, ALT in IR group and EPC group were significantly increased after reperfusion and reached their peak levels at 6 h and 3 h respectively. Compared with EPC group, ALT in IR group increased much higher at 6、12、24 h after reperfusion, but there was no significant differece between the two groups. ⑶ The alterations of the serum AST activity were similar to the ALT. But compared with IR group, AST in EPC group was elevated to a less degree during the liver reperfusion. ⑷In the E group, a normal liver structure was remained, only few inflammatory cells and some denaturalized hepatocytes around centrolobular veins were found. Except for many inflamatory cells and a few necrotic heptocytes around centrolobular veins, no other abnormality was found in EPC group during the reperfusion; A severity of liver damage was observed in IR group.⑸ Under the condition of 40％, 5 g/kg, 24 h prior to ischemia, a less pathological damage, less ALT leakage and high concentration of liver ATP, GSH reservation were observed..2. Study on the protective effect of the ethanol preconditioning against hepatic ischemia/reperfusion injuries .The optimized ethanol preconditioning protocol was adopted to investigate its protection against 90 min I/R liver injuries. Adult male Wistar rats were randomly divided into six groups: the normal control group; 0.9%NS group (NS); ethanol group (E); ischemia/reperfusion group(IR); 0.9%NS preconditioning combined with IR group（NPC）;ethanol preconditioning combined with IR group（EPC）.The mortalities of the rats were observed and serum ALT,AST activity, pathological changes of the liver, apoptic hepatocytes and liver GSH content were measured during the different phases of liver reperfusion. Results: ⑴ No death was found in each group; after 24 h reperfusion, the rats in EPC group recovered completely with a good c

基于生物应激保护原理，以预先胃饲乙醇对实验动物进行预处理，观测和分析其对继后的肝脏缺血—再灌流损害和耐受热缺血安全时限的影响及其与肝细胞hsp70s表达水平的关系，验证此种应激预处理能否增强宿主肝脏对缺血—再灌流的耐受性，为临床上预防肝脏缺血—再灌流损害提供新的途径和方法。

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