DADLE对大鼠急性全脑缺血再灌注Bax、Bcl-2蛋白表达的影响

摘要

目的 观察急性全脑缺血再灌注大鼠脑组织Bax、Bcl-2蛋白表达情况,研究δ阿片受体激动剂DADLE对急性全脑缺血再灌注脑组织凋亡途径的影响以及其与脑保护作用的关系.方法 将健康雌性SD大鼠50只(180 ～ 220 g)随机分为5组:假手术组(Sham组,n=10):只暴露血管而不夹闭；缺血再灌注组(I/R组,n=10):采用改良的二血管阻断加低血压法建立全脑缺血再灌注模型,缺血15rin后给予再灌注；DADLE处理组分为DADLE2 mg/kg组(A组,n=10)、DADLE 3 mg/kg组(B组,n=10)、DADLE 5 mg/kg组(C组,n=10):在I/R组的基础上于再灌注前经颈外静脉注射DADLE.手术结束后,采用免疫组化法检测脑组织Bax、Bcl-2蛋白表达情况.结果 Sham组Bax与Bcl-2阳性细胞数显著少于其他各组(P＜0.05),分别为(20.38±2.84)与(9.62±2.10)；I/R组Bax与Bcl-2阳性细胞数为(52.73±6.08)与(19.49±2.35)；而DADLE处理组中Bax阳性细胞数分别为:A组(43.71±3.85)、B组(37.92±4.08)、C组(36.20±3.94)；Bcl-2阳性细胞数分别为:A组(28.74±2.41)、B组(33.58±2.16)、C组(34.96±1.98).Bcl-2/Bax的比值,Sham组显著高于I/R组[(49.3±3.4)％vs.(35.8±3.2)％,P＜0.05]；DADLE处理组中,A组为(66.4±6.8)％、B组为(85.7±7.3)％、C组为(92.6±6.9)％.结论 在大鼠急性全脑缺血再灌注损伤中,Bax与Bcl-2蛋白的表达均明显上调,而DADLE可以通过影响Bax与Bcl-2的表达程度减少细胞凋亡,发挥脑保护的作用；由Bcl-2/Bax的比值可发现,该作用与使用剂量呈现“S型剂量效应曲线”.%Objective To observe the expressions of Bax and Bcl-2 proteins in the brain tissue of the rats with acute cerebral ischemia reperfusion,and to explore the effect of DADLE,a delta opioid receptor agonist,on brain apoptotic pathways of acute cerebral ischemia reperfusion and the role of DADLE in the protection of brain.Methods 50 healthy female SD rats(180-220 g) were randomly divided into 5 groups:sham operation group (Sham,n =10):only exposed blood vessels without dipping; ischemia reperfusion group (I/R,n =10):modified two-vessel occlusion with hypotension to establish a model of cerebral ischemia,and reperfused 15min after ischemia; DADLE treatment group was subdivided into group of 2 mg/kg(A,n =10),group of 3mg/kg (B,n=10),and group of 5 mg/kg (C,n=10):on the basis of I/R group with reperfusion via external jugular vein injection of DADLE.Expressions of Bax and Bcl-2 proteins were detected by immnnohistochemistry assay after the operation.Results The number of cells with Bax or Bcl-2 expression (20.38 ± 2.84 and 9.62 ±-2.10,P ＜ 0.05)was significantly smaller in Sham group than in the other groups ; In I/R group,the number of cells with Bax or Bcl-2 expression was 52.73 ± 6.08 and 19.49 ± 2.35; In DADLE treatment groups,the number of cells with Bax experssion was 43.71 ± 3.85 for group A,37.92 ± 4.08 for group B,and 36.20 ± 3.94 for group C; the number of cells with Bcl-2 expression was 28.74 ± 2.41,33.58 ± 2.16,and 34.96 ± 1.98,respectively.The ratio of Bcl-2/Bax was significantly higher in Sham group than in I/R group (49.3％-± 3.4％ vs.35.8％ ±3.2％,P＜ 0.05) ; and it was 66.4％ ± 6.8％ in group A,85.7％ ± 7.3％ in group B,and 92.6％ ± 6.9％ in group C.Conelusions In rats with acute cerebral ischemia reperfusion injury,expressions of Bax and Bcl-2 proteins are obviously upregulated.DADLE can play a role in protection of brain by affecting the expression degree of Bax and Bcl-2 and thus lowering apoptosis.Bcl-2Bax ratio shows that the role and the dose is in a S-shape curve of dose-effect.