目的：探讨硫化氢（H2S）预处理对肝硬化大鼠肝脏缺血再灌注损伤（HIRI）的影响及机制。方法：将32 只采用胆总管结扎法制作的肝硬化模型大鼠随机均分为4 组，分别行假手术（假手术组）、30 min 肝门阻断及4 h 再灌注诱导HIRI 模型（HIRI 组）、硫氢化钠（NaHS，外源性H2S 供体）预处理+HIRI 模型诱导（NaHS 组）、NaHS+ 雷帕霉素（RPM，mTOR 抑制剂）预处理+HIRI 模型诱导（RPM组），随后检测血清谷草转氨酶（AST）、谷丙转氨酶（ALT）浓度，分别用光镜与电镜观察肝组织病理学变化与自噬水平，Western blot 检测肝组织LC3-II（自噬特异性标记）以及mTOR、磷酸化mTOR（p-mTOR）蛋白表达。结果：除假手术组外，其余各组肝组织在肝硬化表现的基础上均出现明显的炎症反应、细胞肿胀与局灶性坏死等损伤改变，但NaHS 组的损伤程度明显轻于HIRI 组与RPM 组。与假手术组比较，其他各组血清AST、ALT 水平均明显升高、肝细胞内自噬体数量明显增多、肝组织LC3-II 蛋白表达明显升高，而p-mTOR 蛋白表达（p-mTOR/mTOR 比值）明显降低（均P<0.05），但NaHS 组转氨酶升高幅度、细胞内噬体数量、肝组织LC3-II 蛋白升高及p-mTOR 蛋白降低程度均明显低于HIRI 组（均P<0.05），而RPM 组与HIRI 组间各项指标差异均无统计学意义（均P>0.05）。结论：H2S 预处理能减轻肝硬化大鼠HIRI，其机制可能与通过活化mTOR 途径抑制自噬有关。
Protective effect of hydrogen sulfide against hepatic ischemia-reperfusion injury in cirrhotic rats by autophagy inhibition
Objective: To investigate the influence of hydrogen sulfide (H2S) pretreatment on hepatic ischemia-reperfusion injury (HIRI) in rats with liver cirrhosis and the mechanism. Methods: Thirty-two rats with liver cirrhosis that was induced by common bile duct ligation were equally randomized into 4 groups, and were subjected to sham operation (sham group), HIRI model creation by 30-min hepatic inflow occlusion/4-h reperfusion (HIRI group), sodium hydrosulfide (NaHS, an exogenous H2S donor) pretreatment and then HIRI model creation (NaHS group), and NaHS plus rapamycin (RPM, mTOR inhibitor) pretreatment and then HIRI model creation (RPM group), respectively. Subsequently, the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured, the pathologic and autophagic changes in the liver tissues were observed by light microscope and electron microscope respectively, and the protein expressions of LC3-II (an autophagosome marker), mTOR and phosphorylated mTOR (p-mTOR) in the liver tissues were determined by Western blot analysis. Results: Except in sham group, the liver tissues in all the other groups, apart from the presence of cirrhosis, presented the injury-induced changes that included inflammatory responses, cellular swelling and focal necrosis, but the degree of these changes in NaHS group was markedly milder than that in HIRI group or RPM group. Compared with sham group, the serum levels of AST and ALT were elevated, the number of autophagosomes in hepatic cells was increased, and protein expression of LC3-II was up-regulated while p-mTOR (p-mTOR/mTOR ratio) in liver tissues was down-regulated significantly in the other three groups (P<0.05), in which the amplitude of aminotransferase increase, number of autophagosomes in hepatic cells, degree of LC3-II protein increase and p-mTOR protein decrease in NaHS group were all significantly lower than those in HIRI group (all P<0.05), but all these parameters showed no statistical difference between RPM group and HIRI group (all P>0.05). Conclusion: H2S pretreatment can alleviate HIRI in cirrhotic rats, and its mechanism may be responsible for autophagy inhibition via mTOR signaling pathway activation.