右美托咪定对脑缺血再灌注小鼠NOD样受体蛋白3炎症小体表达的影响

Effect of dexmedetomidine on the expression of NOD like receptor protein 3 inflammatory bodies during cerebral ischemia-reperfusion in mice

目的研究右美托咪定对小鼠脑缺血再灌注时NOD样受体蛋白3(NLRP3)炎症小体表达的影响。方法将45只清洁级健康成年雄性C57BL/6J小鼠采用公认的大脑中动脉栓塞法建立脑缺血再灌注损伤模型,造模成功后将其分为假手术组、模型组、右美托咪定组各15只。右美托咪定组小鼠经腹腔预先30 min注射25μg·kg^(-1)右美托咪定,同期模型组和假手术组注射等量0.9%NaCl。进行水迷宫测试并在行为学测试完毕后2 h处死小鼠,取部分脑组织以及海马组织,用伊文斯蓝法检测脑组织血脑屏障的通透性,同时测定海马组织湿/干重比(W/D);用酶联免疫吸附法检测血清中白细胞介素(IL)-1β、IL-18水平,用蛋白质印迹法检测各组小鼠NLRP3、胱天蛋白酶-1(caspase-1)、ASC型氨基酸转运蛋白(ASC)的表达情况。结果术前1 d,3组逃避潜伏期以及游泳距离比较,差异无统计学意义(P>0.05)。而术后3、7 d,模型组、右美托咪定组小鼠逃避潜伏期以及游泳距离相较于假手术组均显著升高(P<0.05),而右美托咪定组小鼠逃避潜伏期以及游泳距离较模型组明显偏低(均P<0.05)。假手术组、模型组、右美托咪定组的W/D分别为(3.33±0.37),(4.75±0.44)和(4.23±0.35),IL-1β分别为(4.67±0.44),(22.48±2.48)和(8.62±0.78)ng·L^(-1),IL-18分别为(45.04±3.93),(155.05±13.47)和(73.38±7.19)ng·L^(-1),模型组、右美托咪定组的上述指标与假手术组比较,差异均有统计学意义(均P<0.05),同时右美托咪定组的上述指标与模型组比较,差异均有统计学意义(均P<0.05)。结论右美托咪定预处理可通过抑制海马组织NLRP3炎症小体激活,进一步阻断其下游炎症反应,以缓解小鼠缺血再灌注脑损伤并改善其学习记忆能力。

Objective To investigate the effect of dexmedetomidine on the expression of NOD like receptor protein 3(NLRP3)inflammatory bodies during cerebral ischemia-reperfusion in mice.Methods Forty-five clean grade healthy adult male C57BL/6J mice were established cerebral ischemia-reperfusion injury model by middle cerebral artery embolization.After successful modeling,they were divided into sham operation group,model group and dexmedetomidine group(Dex group).Mice in Dex group were injected with 25μg·kg^(-1)dexmedetomidine intraperitoneally for 30 min,model group and sham operation group were injected with the same amount of normal saline.The water maze test was performed,and the mice were killed 2 h after the behavioral test.Some brain tissues and hippocampal tissues were taken.The permeability of blood-brain barrier in brain tissue was detected by Evans blue method,and the wet/dry weight ratio(W/D)of hippocampal tissue was measured;enzyme-linked immunosorbent assay was used to detect interleukin(IL)-1βand IL-18 levels in mouse serum,Western blot was used to detect the expression of NLRP3,caspase-1 and ASC in each group of mice.Results One day before operation,there was no significant difference in escape latency and swimming distance among the three groups(P>0.05).At 3 and 7 days after operation,the escape latency and swimming distance of model group and Dex group were significantly higher than those of sham operation group(P<0.05),while the escape latency and swimming distance of Dex group were significantly lower than those of model group(P<0.05).The W/D of sham operation group,model group and Dex group were(3.33±0.37),(4.75±0.44)and(4.23±0.35);IL-1βwere(4.67±0.44),(22.48±2.48)and(8.62±0.78)ng·L^(-1);IL-18 were(45.04±3.93),(155.05±13.47)and(73.38±7.19)ng·L^(-1);the relative expression levels of NLRP3 were 0.26±0.02,1.09±0.09 and0.76±0.07;the above indexes of model group and Dex group were significantly different compared with sham operation group(all P<0.05),Dex group compared with model group,the difference were statistically significant(all P<0.05).Conclusion Dexmedetomidine pretreatment can further block the downstream inflammatory response by inhibiting the activation of NLRP3 inflammatory body in hippocampus,so as to alleviate the cerebral ischemiareperfusion injury and improve its learning and memory ability in mice.