中文摘要：

目的探究老年大鼠肝脏缺血再灌注损伤抑制自噬的作用及其机理。方法选取鼠龄为3个月（3M）和24个月（24M）健康雄性Lewis大鼠，采用随机数字表法将大鼠分为3MIRI组、3M假手术组、24MIRI组、24M假手术组。实验组采用无创血管夹夹闭肝左叶及中叶血流（约70％肝缺血），肝脏在常温下（37℃±0．5℃）缺血30min，再灌注6h。假手术组仅解剖分离肝十二指肠韧带。术后6h，采集各组大鼠血清样本，检测血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）等肝功能指标，取各组大鼠肝组织进行肝脏病理检查，共聚焦显微镜下观察各组大鼠肝组织中LC3B自噬小体的数量，并采用蛋白质印迹法分析自噬相关蛋白的变化。结果经历缺血再灌注损伤后，24MIRI组大鼠血清ALT和AST水平较3MIRI组显著升高，两组比较，差异有统计学意义（P〈0.05）。肝脏病理检查结果显示，3MIRI组大鼠肝脏主要表现为点灶状坏死，24MIRI组大鼠肝脏主要表现为片状坏死及混合炎症细胞浸润。共聚焦结果显示，24M假手术组大鼠肝组织中自噬小体数量较3M假手术组略有下降，但经历缺血再灌注损伤后，24MIRI组大鼠肝组织中自噬小体数量较3MIRI组显著下降（P〈0．05），并且24MIRI组大鼠肝组织自噬相关蛋白（Beclin1蛋白和ATG4B蛋白）水平较3MIRI组严重下调（P〈0．05）。结论老年大鼠肝脏缺血再灌注损伤抑制了自噬作用，其机理可能与肝脏缺血再灌注损伤使自噬相关蛋白水平的显著下降有关。

英文摘要：

Objective To explore the mechanism of hepatic autophagy inhibition induced by ischemia-reperfusion injury in the aging liver. Methods The healthy male Lewis rats aged 3 months （3M） and 24 months （24M） were selected, and then were randomly divided into 3M IRI group, 3M sham operation group, 24M IRI group, 24M sham operation group. In the experimental group, non- invasive vascular clamp was used to clamp the left and middle hepatic lobes （about 70% hepatic ischemia）. The liver was subjected to ischemia at 37 0. 5℃ for 30min and reperfusion for 6h. The hepatic duodenal ligament was dissected only by sham operation. The serum levels of serum alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were measured at 6 h after operation. Liver tissues of each group were examined by liver pathology and the number of autophagosome of LC3B in liver tissue of each group was observed under confocal microscopy. The changes of autophagy- related protein were analyzed by Western blotting. Results The levels of serum ALT and AST in 24M IRI group were significantly higher than those in 3M IRI group, the difference was statistically significant （P〈0. 05）. Pathological analysis showed that 3M IRI group showed spotty necrosis, the 24M IRI group showed massive necrosis and the infiltration of the inflammatory cells; Confocal microscopy showed that the number of autophagosome in the liver tissue of the 24M sham group was slightly lower than that of the 3M sham operation group and the number of autophagosome in the 24M IRI group was significantly lower than that in the 3M IRI group （P〈0.05）. The levels of autophagy-related proteins （Beclinl and ATG4B protein） in 24M IRI group were significantly down-regulated compare to 3M IRI group （P〈0. 05）. Conclusion The ischemia - reperfusion injury of liver in aged rats inhibits autophagy, and its mechanism may be related to the decrease of autophagy - related protein level in hepatic ischemia reperfusion injury.