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脑卒中病人数正在逐年上涨,其严重的后遗症极大地影响了病人的生存质量[1]。缺血性脑卒中相对于脑出血发病率更高,在临床上也更为常见[2]。脑卒中常见的治疗方法是通过溶栓或机械再通来恢复脑部的血流供应,这也是拯救有活力的脑细胞的第一步,但疏通血管、恢复血流后可能会加重之前缺血的损伤,称为脑缺血再灌注损伤(ischemia and reperfusion injury,I/R)[3]。脑卒中发生时伴有炎症产生,炎症反应亦会加速脑卒中的进展。
核苷酸结合寡聚化结构域受体蛋白3(NLRP3)炎症小体是介导缺血/再灌注后炎症反应的重要靶向蛋白[4]。NLRP3属于NLRs家族蛋白,在小胶质细胞、星形胶质细胞、神经元细胞、内皮细胞等神经元细胞内存在不同程度表达[5-7],能够被高糖、高脂、炎症因子、氧化应激等致病要素所激活,NLRP3被激活后与caspase-1前体和凋亡相关斑点样蛋白共同构成了炎症小体,随后被活化切割的caspase-1会招募活化更多的白细胞介素-1β(IL-1β)和IL-18[8],进一步加重了炎症反应[9]。乙醛脱氢酶2(ALDH2)作为线粒体中的关键酶蛋白[10],具有清除4-羟基壬烯醛(4-HNE)的作用,同时ALDH2可抑制NLRP3炎症小体的生成[11]。有研究[12]发现,ALDH2的活性下降后,大鼠的神经功能受损,脑梗死面积增加,加重了缺血再灌注对脑神经的损伤。ALDH2过表达可以减轻心肌细胞纤维化,减少炎症因子的生成,从而对心肌起到保护作用[13]。通过激活ALDH2在脑神经元中的表达是否可抑制神经元炎症反应发挥保护作用,目前相关报道较少。Bax介导的细胞色素c释放抑制剂(Bax channel blocker,Bcb)通过调控Bax通道抑制细胞色素c从线粒体释放,常作为凋亡抑制剂用于减轻细胞凋亡的发生[14-15]。抑制线粒体细胞色素c释放是否可通过调控炎症反应改变I/R,Bcb是否可调控脑组织ALDH2的表达目前鲜见报道。
本研究拟通过给予Bcb和ALDH2激动剂,观察此法干预对大鼠全脑I/R产生的作用,分析线粒体色素c释放抑制剂在调控线粒体ALDH2和炎症反应中发挥的保护作用。现作报道。
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HE染色结果表明,Sham组大鼠海马CA1区神经元排列整齐,细胞核为圆形或椭圆形。核膜核仁结构完整,明显,细胞质体积较小,呈淡红色。与Sham组比较,I/R组再灌注7 d后,神经元细胞排列散乱,细胞核固缩深染,海马CA1区界限不明显,神经元的存活率明显下降(见图 1)。与I/R组比较,Alda-1+I/R组、Bcb+I/R组海马CA1区神经元存活率提高(P < 0.01)(见表 1)。
分组 n 神经元存活率/% Sham组 8 0.936±0.028 I/R组 8 0.130±0.031** Alda+I/R-1组 8 0.793±0.084**△△ Bcb+I/R组 8 0.731±0.081**△△## F — 264.28 P — < 0.01 MS组内 — 0.004 q检验:与Sham组比较**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 表 1 各组大鼠脑I/R后海马CA1区神经元存活率的比较(x±s)
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与Sham组比较,I/R组7 d后,海马CA1区组织中NLRP3棕黄色阳性染色明显加深,ALDH2棕黄色阳性染色明显减弱,提示NLRP3蛋白表达增加,ALDH2蛋白表达下降(见图 2)。与I/R组比较,Alda-1+I/R组、Bcb+I/R组海马CA1区组织中NLRP3蛋白表达下降,ALDH2蛋白表达增加(P < 0.01)(见表 2)。
分组 n NLRP3 IDO ALDH2 IDO Sham组 8 0.000±0.000 0.003±0.000 I/R组 8 0.004±0.001** 0.000±0.000** Alda-1+I/R组 8 0.001±0.000*△△ 0.002±0.001△△ Bcb+I/R组 8 0.001±0.000*△△ 0.001±0.000**△△## F — 40.257 32.996 P — < 0.01 < 0.01 MS组内 — 0.000 0.000 q检验:与Sham组比较*P < 0.05,**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 表 2 各组大鼠脑I/R后海马CA1区NLRP3和ALDH2蛋白吸光度变化的比较(x±s)
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Western blotting结果显示,与Sham组对比,脑I/R 48 h后海马CA1区NLRP3、IL-1β、IL-18蛋白表达增加(P < 0.01);与I/R组相比,Alda-1+I/R组、Bcb+I/R组的海马CA1区NLRP3、IL-1β、IL-18蛋白表达减少(P < 0.01),提示激动ALDH2、抑制线粒体细胞色素c释放均可引起NLRP3炎症小体和相继的炎症反应减轻(见图 3、表 3)。
分组 n IL-1β IL-18 NLRP3 ALDH2 4-HNE Sham组 8 0.486 2±0.073 3 0.246 6±0.030 9 0.508 0±0.006 4 0.787 7±0.067 4 0.739 4±0.089 5 I/R组 8 0.847 0±0.037 7** 0.615 4±0.029 1** 1.022 3±0.102 9** 0.403 6±0.050 2** 1.417 2±0.180 5** Alda-1+I/R组 8 0.650 0±0.080 9**△△ 0.381 5±0.038 4**△△ 0.642 0±0.096 4*△△ 1.068 6±0.091 3**△△ 0.491 5±0.118 8*△△ Bcb+I/R组 8 0.636 7±0.066 2**△△ 0.475 3±0.053 1**△△## 0.739 8±0.078 2**△△ 0.783 0±0.081 5△△## 0.393 6±0.063 0**△△ F — 19.77 63.31 29.22 54.07 58.06 P — < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 MS组内 — 0.004 0.002 0.007 0.006 0.015 MS组间 — 0.088 0.097 0.190 0.298 0.851 q检验:与Sham组比较*P < 0.05,**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 表 3 各组大鼠脑I/R后海马CA1区炎症小体相关蛋白灰度值比较(x±s)
线粒体细胞色素c释放抑制剂对大鼠全脑缺血再灌注损伤炎症反应的作用
Effect of mitochondrial cytochrome c release inhibitor on the inflammatory response of rats with global cerebral ischemia reperfusion injury
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摘要:
目的探讨线粒体细胞色素c抑制剂对大鼠全脑缺血再灌注后脑损伤的作用,分析线粒体乙醛脱氢酶2(ALDH2)和炎症反应在其中的机制。 方法通过四血管阻断法模拟大鼠全脑缺血再灌注损伤(I/R)模型,雄性SD大鼠随机分为假手术组(Sham组)、I/R组、ALDH2激动剂Alda-1+I/R组、Bax介导的线粒体细胞色素c释放抑制剂(Bcb)+I/R组。HE染色观察海马CA1区细胞形态学的变化;免疫组织化学观察海马CA1区ALDH2及炎症小体关键蛋白NLRP3表达水平,Western blotting检测海马CA1区4-HNE、NLRP3、IL-1β、IL-18及ALDH2的蛋白水平变化。 结果与Sham组比较,I/R组再灌注7 d后,I/R组海马CA1区细胞存活率明显下降;与I/R组比较,Alda-1+I/R组、Bcb+I/R组的海马CA1区神经元存活率增高(P < 0.01)。与I/R组相比,Bcb+I/R组、Alda-1+I/R组海马CA1区ALDH2蛋白表达增加,海马CA1区NLRP3、IL-1β、IL-18、4-HNE蛋白表达下降(P < 0.01)。 结论大鼠全脑缺血再灌注损伤模型中,海马CA1区NLRP3表达增高;Bcb可以通过促进线粒体ALDH2的表达、降低炎症反应发挥保护作用。 -
关键词:
- 脑缺血再灌注损伤 /
- 线粒体细胞色素c抑制剂 /
- 核苷酸结合寡聚化结构域受体蛋白3 /
- 线粒体乙醛脱氢酶2 /
- 大鼠
Abstract:ObjectiveTo explore the effects of mitochondrial cytochrome c inhibitor on the cerebral injury in rats with global cerebral ischemia-reperfusion injury, and analyze the possible mechanisms of mitochondrial aldehyde dehydrogenase 2(ALDH2)and inflammatory response. MethodsThe rat model with global cerebral ischemia and reperfusion injury(I/R) was simulated by four-vessel occlusion.The male SD rats were randomly divided into the sham group, I/R group and ALDH2 agonist Alda-1+I/R group and Bax-mediated mitochondrial cytochrome c release inhibitor(Bcb)+I/R group.The HE staining was used to observe the morphological changes of hippocampal CA1 cells.The expressions of ALDH2 protein and inflammasome-related protein NLRP3 in hippocampal CA1 were observed by immunohistochemistry.The protein changes of 4-HNE, NLRP3, IL-1β, IL-18 and ALDH2 in hippocampal CA1 were detected by Western blotting. ResultsCompared with the sham group, the survival rate of hippocampal CA1 region cells in the I/R group decreased significantly after 7 d of reperfusion(P < 0.01).Compared with the I/R group, the survival rate of hippocampal CA1 neurons in ALDA-1 +I/R group and Bcb+I/R group increased(P < 0.01).Compared with the I/R group, the expression of ALDH2 protein increased in Bcb+I/R group and ALDA-1 +I/R group, while the expressions of NLRP3, IL-1β, IL-18 and 4-HNE proteins in hippocampal CA1 region decreased(P < 0.01). ConclusionsThe expression of NLRP3 in hippocampal CA1 increases in rats with global cerebral I/R injury model.The Bcb may play a protective role by promoting the mitochondrial ALDH2 expression and reducing inflammatory response. -
表 1 各组大鼠脑I/R后海马CA1区神经元存活率的比较(x±s)
分组 n 神经元存活率/% Sham组 8 0.936±0.028 I/R组 8 0.130±0.031** Alda+I/R-1组 8 0.793±0.084**△△ Bcb+I/R组 8 0.731±0.081**△△## F — 264.28 P — < 0.01 MS组内 — 0.004 q检验:与Sham组比较**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 表 2 各组大鼠脑I/R后海马CA1区NLRP3和ALDH2蛋白吸光度变化的比较(x±s)
分组 n NLRP3 IDO ALDH2 IDO Sham组 8 0.000±0.000 0.003±0.000 I/R组 8 0.004±0.001** 0.000±0.000** Alda-1+I/R组 8 0.001±0.000*△△ 0.002±0.001△△ Bcb+I/R组 8 0.001±0.000*△△ 0.001±0.000**△△## F — 40.257 32.996 P — < 0.01 < 0.01 MS组内 — 0.000 0.000 q检验:与Sham组比较*P < 0.05,**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 表 3 各组大鼠脑I/R后海马CA1区炎症小体相关蛋白灰度值比较(x±s)
分组 n IL-1β IL-18 NLRP3 ALDH2 4-HNE Sham组 8 0.486 2±0.073 3 0.246 6±0.030 9 0.508 0±0.006 4 0.787 7±0.067 4 0.739 4±0.089 5 I/R组 8 0.847 0±0.037 7** 0.615 4±0.029 1** 1.022 3±0.102 9** 0.403 6±0.050 2** 1.417 2±0.180 5** Alda-1+I/R组 8 0.650 0±0.080 9**△△ 0.381 5±0.038 4**△△ 0.642 0±0.096 4*△△ 1.068 6±0.091 3**△△ 0.491 5±0.118 8*△△ Bcb+I/R组 8 0.636 7±0.066 2**△△ 0.475 3±0.053 1**△△## 0.739 8±0.078 2**△△ 0.783 0±0.081 5△△## 0.393 6±0.063 0**△△ F — 19.77 63.31 29.22 54.07 58.06 P — < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 MS组内 — 0.004 0.002 0.007 0.006 0.015 MS组间 — 0.088 0.097 0.190 0.298 0.851 q检验:与Sham组比较*P < 0.05,**P < 0.01;与I/R组比较△△P < 0.01;与Alda-1+I/R组比较##P < 0.01 -
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