二氮嗪预处理抑制大鼠肝缺血再灌注所致细胞凋亡的延迟保护作用

目的：探讨二氮嗪(DE)预处理模拟缺血预处理(IP)抑制肝缺血再灌注(I/R)损伤所致细胞凋亡的延迟保护(DP)作用及其可能机制。方法：大鼠随机分为5组:IP组以肝缺血5min作I/R预处理;DE组静脉注射DE 作I/R预处理;DE+5-HD组在DE组基础上再予静脉注射5-HD作预处理;对照组(C组)仅以等量生理盐水作预处理;假手术组（S组）仅行2次开腹手术，不作其他处理。4个预处理组均在24h后行肝缺血1h再灌注3h。切取肝组织用免疫组化法检测Bcl-2蛋白表达及用TUNEL法检测肝细胞凋亡,并观察显微结构变化。结果： C组肝细胞凋亡指数(AI)明显高于S组(P<0.01),光镜与电镜下肝脏结构损伤明显;IP组与DE组Bcl-2蛋白表达指数(BI)高于C组(P<0.01),AI明显低于C组(P<0.05),组织损伤也轻于C组;而DE+5-HD组BI低于DE组(P<0.01),AI则高于DE组(P<0.05)。结论：使用DE预处理能模拟IP抗大鼠I/R损伤所致肝细胞凋亡的DP作用,可能系通过诱导肝细胞Bcl-2蛋白表达上调而发挥抗凋亡作用。

Study on the delayed protection of diazoxide preconditioning inhibition of ischemia/reperfusion induced hepatocyte apoptosis in rats

Objective To determine the delayed protective effect of diazoxide(DE), as an ischemic preconditioning (IPC) simulator, on inhibition of ischemia/reperfusion induced hepatocyte apoptosis in rats. Methods Four groups of SD rats (n=8 each) were pretreated with: (1) 5-min period of liver ischemia (IPC group); (2) DE 5mg/kg iv (DE group), (3) DE plus 5-hydroxydecanoate (DE+5-HD group), and (4) with saline(control or C group). Twenty-four hours later, the pretreated rats were subjected to 60-min sustained liver ischemia followed by 180-min reperfusion. All rats were only subjected to 70% liver ischemia. An additional fifth (S)group of rats (sham group) was set up, in which only anesthesia and laparotomy were performed twice. Finally, liver samples were obtained to determine apoptotic cells by TUNEL, and the expressions of Bcl-2 protein by immunohistochemical technique, and pathology.Results Apoptosis index were higher in C group than those in S group (P<0.01). There were also severe morphologic damages in C group. The levels of expression of Bcl-2 protein were increased (P<0.01) and apoptosis index were decreased (P<0.05) in IPC group and DE group compared with C group. DE+5-HD group had the opposite changes, contrasted to DE group (P<0.05,P<0.01). Conclusions DE can mimic the delayed protective effects of IPC, and induce delayed protection against hepatocyte apoptosis, possibly due to increased expression of the Bcl-2 protein.