右美托咪定抑制NF-κB核易位减轻大鼠创伤性脑损伤神经炎症

Dexmedetomidine attenuates neuroinflammation by inhibiting NF-κB nuclear translocation in rats with traumatic brain injury

目的探究右美托咪定(dexmedetomidine,DEX)调节创伤性脑损伤(traumatic brain injury,TBI)后小胶质细胞(microglial,MG)极化及神经炎症的机制。方法42只成年雄性SD大鼠按随机数字表法分为假手术组(sham组)、TBI组、TBI+DEX组(又分为治疗1 d、3 d和7 d组)、TBI+NF-κB抑制剂(pyrrolidine dithiocarbamate,PDTC)组和TBI+DEX+PDTC组,每组6只。采用改良Feeney自由落体法制备大鼠TBI模型,造模后1 h腹腔注射PDTC 100 mg/kg、2 h腹腔注射DEX 100μg/kg,直至取材。于取材前采用改良的神经功能缺损评分法(modified neurological severity score,mNSS)评价大鼠神经功能,ELISA检测血清炎症因子,取大鼠损伤皮质通过Western Blot检测MG M1和M2表型标记物及MyD88、NF-κB p65蛋白表达,免疫荧光染色观察损伤皮质处NF-κB p65在MG中的表达及入核情况。计量资料多组间比较采用单因素及双因素方差分析。结果与Sham组相比,TBI组mNSS评分显著升高,DEX组mNSS评分明显低于TBI组,差异有统计学意义(P<0.05);ELISA和Western Blot检测TBI组血清中肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)和白介素(interleukin,IL)-1β水平及MG M1表型标记物(IL-1β和TNF-α)升高,抗炎因子IL-10和M2型标记物(精氨酸酶-1和IL-10)表达下降(P<0.05);DEX降低血清TNF-α及IL-1β的水平,提高IL-10水平,并促进MG M2表型极化(P<0.05)。此外,DEX组MyD88表达下调,NF-κB p65核易位被抑制,该效应可被PDTC增强。结论DEX可通过抑制NF-κB核易位调节TBI大鼠MG活化,减轻神经炎症。

Objective To explore the mechanism of dexmedetomidine(DEX)regulating microglial(MG)polarization and neuroinflammation after traumatic brain injury(TBI)in rats.Methods Forty-two adult male SD rats were randomly(random number)divided into the sham group,TBI group,TBI+DEX group(further divided into 1 d,3 d and 7 d subgroups),TBI+NF-κB inhibitor(pyrrolidine dithiocarbamate,PDTC)group and TBI+DEX+PDTC group,with 6 animals in each group.The rat TBI model was established according to the modified Feeney free fall method.PDTC was intraperitoneally injected 1 h after modeling with a dose of 100 mg/kg,and DEX was intraperitoneally injected 2 h after modeling with a dose of 100μg/kg.Modified neurological severity score(mNSS)was used to evaluate rat neurological function,ELISA was used to detect serum inflammatory factors,and rats’damaged cortex was collected to detect the phenotype markers of MG and protein expressions of MyD88 and NF-κB p65,and immunofluorescence staining was used to observe the expression and nuclear entry of NF-κB p65 in MG in injured cortex.One-way and two-way ANOVA were used to compare the measurement data among multiple groups.Results Compared with the sham group,the mNSS score was significantly higher in the TBI group,and DEX treatment significantly decreased the mNSS score of TBI rats(P<0.05).ELISA and Western blot results showed that in the TBI group,the tumor necrosis factor-α(TNF-α),interleukin(IL)-1βin serum and M1 phenotype marker(TNF-α,IL-1β)in brain were increased,the expression of anti-inflammatory factor IL-10 in serum and M2 phenotype markers(arginase-1 and IL-10)in brain were decreased(P<0.05),and DEX downregulated the expression of TNF-α,IL-1βin serum and M1 phenotype markers in brain,while upregulated the level of L-10 in serum and the M2 phenotype marker in brain(P<0.05).In addition,the expression of MyD88 and the nuclear translocation of NF-κB p65 were inhibited in the DEX group,and this effect could be enhanced by PDTC.Conclusions DEX modulates MG activation in TBI rats by inhibiting NF-κB nuclear translocation and reduces neuroinflammation.