探讨乳果糖预处理对大鼠肝缺血-再灌注损伤(IRI)的保护作用及其机制。

将45只Sprague-Dawley（SD）大鼠按随机数字表法随机分为假手术组、肝IRI组（IRI组）、乳果糖灌胃预处理组（乳果糖组），每组15只。乳果糖组手术前7 d每天应用0.1 g/ml的乳果糖灌胃，IRI组及假手术组手术前7 d每天给予等体积的生理盐水灌胃。手术中IRI组和乳果糖组用血管夹夹闭肝左、中叶的门静脉分支和相应的肝动脉分支，使约70%的肝脏缺血，阻断60 min后恢复肝脏供血，再灌注6 h，建立IRI模型。假手术组仅开腹暴露并离断肝脏周围韧带。手术完成后应用酶联免疫吸附试验检测血清白介素（IL）-1β、IL-6、肿瘤坏死因子（TNF）-α水平，光镜下观察肝组织形态变化，荧光显微镜下观察肝细胞凋亡情况，蛋白质印迹法检测激活型caspase-3的表达。3组大鼠细胞因子检测数据的比较采用单因素方差分析和LSD-t检验。

假手术组、IRI组和乳果糖组大鼠血清IL-1β水平分别为（75±22）、（365±30）、（139±16）ng/L，IL-6水平分别为（48±16）、（190±22）、（92±10）ng/L，TNF-α水平分别为（11.3±5.1）、（40.2±2.7）、（19.5±3.9）ng/L，IRI组的血清IL-1β、IL-6、TNF-α水平明显高于假手术组（LSD-t=30.6，20.6, 19.4；P<0.05），而低于乳果糖组（LSD-t=-26.2，-16.1，-16.9；P<0.05）。假手术组大鼠肝组织形态正常，IRI组肝细胞呈灶状或片状大面积坏死，乳果糖组肝细胞水肿变性，见点状坏死，组织结构破坏程度比IRI组减轻。假手术组未见明显凋亡细胞，乳果糖组与IRI组的凋亡细胞数明显增多，但乳果糖组凋亡细胞数少于IRI组。乳果糖组激活型caspase-3表达较假手术组上调，但较IRI组下调。

乳果糖预处理能减轻大鼠肝脏IRI，其作用机制可能与抑制炎症细胞因子释放和抑制细胞凋亡有关。

To investigate the protection and mechanism of lactulose preconditioning on liver ischemia-reperfusion injury (IRI) in rats.

Forty-five Sprague-Dawley rats were randomly divided into three groups by random number table: sham-operation (SO) group, IRI group, lactulose preconditioning (lactulose) group with 15 rats in each group. Lactulose (0.1 g/ml) was administered daily via gavage in lactulose group 7 d before operation, while equal volume of normal saline was administered via gavage in IRI and SO group. In IRI and lactulose group, the portal vein and corresponding hepatic artery branches of middle and left hepatic lobes were clamped with bulldogs clamps during the operation to make 70% of the liver in ischemia, and blood supply recovered after 60 min′s blocking, and reperfusion was performed for 6 h to establish IRI model. In SO group, the rats only underwent open surgery and hepatic ligaments were exposed and separated. After operation, the levels of serum interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were detected by enzyme linked immunosorbent assay. The morphological change of liver tissue was observed under light microscope. Hepatocyte apoptosis was observed under fluorescence microscope. The expression of activated caspase-3 was detected by Western blot. The detecting data of cytokines in rats among 3 groups were compared by one-way analysis of variance and LSD-t test.

The level of IL-1β in SO, IRI and lactulose group was (75±22), (365±30), (139±16)ng/L respectively, and the level of IL-6 was (48±16), (190±22), (92±10)ng/L respectively, and the level of TNF-α was (11.3±5.1), (40.2±2.7), (19.5±3.9)ng/L respectively. The levels of IL-1β, IL-6, TNF-α in IRI group were significantly higher than those of SO group (LSD-t=30.6, 20.6,19.4; P<0.05), while were significantly lower than those of lactulose group (LSD-t=-26.2, -16.1, -16.9; P<0.05). Normal morphology of liver tissue was observed in SO group. Large area of focal or patchy necrosis of hepatocytes was observed in IRI group. Hydropic degeneration and spotty necrosis were observed in lactulose group, and its tissue structure damage was milder than that of IRI group. No obvious apoptosis was observed in SO group. The number of apoptosis obviously increased in lactulose and IRI group, while the number of apoptosis in lactulose group was less than that of IRI group. Compared with the SO group, the expression of activated caspase-3 in lactulose group was up-regulated, but more down-regulated than the IRI group.

Lactulose preconditioning can alleviate liver IRI in rats, which may be related with the inhibition of inflammatory cytokine release and the inhibition of apoptosis.