缺血后处理对大鼠再灌注损伤肺细胞凋亡的影响

Effects of ischemic postconditioning on pneumocyte apoptosis after lung ischemia/reperfusion injury in rats

目的:探讨缺血后处理对再灌注损伤肺细胞凋亡的影响。方法:健康雄性SD大鼠24只,随机分为对照组(C组)、缺血/再灌注组(I/R组)和缺血后处理组(IPostC组)(n=8)。对比观察各组血清中丙二醛(MDA)、超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)活力及含量变化,原位缺口末端标记法(TUNEL)检测肺组织细胞凋亡情况,免疫组化及RT-PCR法检测肺组织中Bax、Bcl-2蛋白和基因的表达。结果:I/R组与C组相比,MDA含量、MPO活力明显升高,SOD活力明显下降(均P<0.01),肺组织原位细胞凋亡检测示I/R组凋亡指数(AI)(39.03±3.46)显著高于C组(2.88±0.34),Bcl-2/Bax比值在蛋白和基因水平明显降低(均P<0.01);IPostC组与I/R组相比MDA含量显著降低(P<0.05),MPO活力显著降低(P<0.01),SOD活性升高(P<0.01),AI为8.03±0.88显著低于I/R组,并能明显升高Bcl-2/Bax比值(均P<0.01)。结论:缺血后处理通过减轻脂质过氧化反应及中性粒细胞聚集,降低Bax/Bcl-2比值,使肺组织细胞凋亡减少,从而有效地减轻肺缺血/再灌注损伤。

Objective： To investigate the effects of ischemic postconditioning （IPostC） on pneumocyte apoptosis after lung ischemia/ reperfusion injury in rats. Methods： Adult male SD rats were randomly divided into 3 groups based upon the intervention （ n = 8） ： control group （C）, lung ischemicl reperfusion group （LIR）, LIR ＋ IPostC group （IPostC）. At the end of the experiment , blood specimens drawn from the arteria carotis were tested for the content of malondialdehyde （MDA）, the activity of superoxide dismutase （ SOD）and myeloperoxidase （MPO）; the pneumocyte apoptosis index （M） was achieved by terminal deoxynucleotidyl transferase mediated dUTP nick end abehng （TUNEL） ; the expression ofBcl-2, Bax protein in lung tissue was accessed by quantitative immanohistochemistry （IHC） and Bcl-2, Bax mR- NA by RT-PCR. Results： IPostC could significantly attenuate the MDA level, MPO activity and improve SOD activity in blood serum which was comparable to I/R and significantly reduced the number of TUNEL-positive cells compared with I/R group, expressed as AI （ % total nu- clei） from（ 39.0 ＋ 3.46 ）to（ 8.0 _＋ 0.88）（ P 〈 0.01 ）. The protein and mRNA expression of Bcl-2 and Bax showed that IPO significantly atten- uated the isehemia/reperfusion-upregulated expression of Bax protein but improved the expression of Bcl-2 that improved the Bcl-2/Bax ratio （ P 〈 0.01 ）. Conclusion： IPostC may attenuate pneumocyte apoptosis in LIRI by up-regulating expression of Bcl-2/Bax ratio and by inhibit- ing oxidant generation and neutmphils filtration.