NBD多肽预处理对局灶脑缺血再灌注大鼠脑内核因子-κB核转位活化的影响

目的探讨NBD多肽预处理对局灶脑缺血再灌注大鼠大脑缺血皮质细胞内核因子-κB活化的影响。方法将SD健康雄性大鼠（280～300g）共36只随机分为假手术组（n=6）、模型组（n=15）、药物组（n=15）。缺血模型制备前2h经右侧侧脑室注射NBD多肽25μl进行预处理。运用改良线栓法制备右侧大脑中动脉闭塞再灌注大鼠模型。运用免疫组化检测再灌注后72hNF-κBp65在胞浆／胞核的蛋白表达变化；运用免疫荧光定位及Western印迹（半定量）检测NF-κB p65及IκBα的蛋白表达情况。结果免疫组化结果显示与假手术组比较，再灌注72h模型组胞浆／胞核内NF-κB p65大量表达（P〈0．05）；NBD多肽预处理后NF-κB p65主要在胞浆表达，胞核内表达明显减少（P〈0．05）；免疫荧光双标定位及Western印迹半定量检测显示模型组胞浆／胞核内NF-κB p65蛋白均大量表达（P〈0．05），IκBα蛋白呈现低表达（P〈0．05）；NBD多肽预处理后胞核内NF-κB p65蛋白表达明显减少，主要以胞浆表达为主（P〈0．05），IκBα胞浆／胞核内表达显著增加（P〈0．05）。结论局灶脑缺血再灌注72hNF-κB p65蛋白胞核表达明显增加．NF-κB核转位／活化过程被激活：NBD多肽预处理后通过增加胞核／胞浆内IκBα表达有效阻止NF-κB的核转位／活化过程，从而有效地减轻再灌注后72h局灶脑缺血再灌注对脑组织的损害。

Effect ofNBD Peptide Preconditioning on Nuclear Translocation and Activation of NF-κB in Brain Tissues of Rats with Focal Cerebral Is- chemia/Reperfusion Injury

Objective To investigate the effect of NBD peptide preconditioning on the nuclear translocation and activation of NF-κB after the focal cerebral ischemia/reperfusion （I/R） inju- ry. Methods Thirty-six healthy male SD rats were randomly divided into I/R group, NBD group and sham group. NBD peptide （25 μl） was intracerebroventricularly injected 2 h before the focal cerebral I/R models were established by middle cerebral artery occlusion/reperfusion. The NF-κB p65 protein expression in the cytoplasm and nucleus was immunohistochemically detec- ted. Immunofluorescenee staining and Western blotting were used to measure the protein expression of NF-κB p65 and IκBα 72 h after reperfusion. Results The NF-κB p65 protein was intensely ex- pressed in both the cytoplasm and nucleus of neurons in the I/R group relative to the sham group, mainly in the nucleus at 72 h after reperfusion （P 〉 0. 05 ） . Meanwhile, there was little expressionof IκBα protein in the nucleus and cytoplasm of neurons （P 〈 0. 05 ） . After the NBD peptide pre- treatment, the NF-κB p65 protein expression was predominantly found in the cytoplasm rather than in the nucleus （P 〈 0. 05）, and the IκBα protein expression in the cytoplasm and nucleus was sig- nificantly increased （P 〈 0. 05 ） . Conclusion The NBD peptide preconditioning could inhibit the nuclear translocation and activation of NF-κB by increasing the IκBα protein expression and there- fore alleviate the cerebral damage caused by I/R.