目的观察雷公藤甲素(TP)对大鼠弥漫性轴索损伤(DAI)后继发性轴索损伤的保护作用,探讨雷公藤甲素调控炎性反应减轻DAI的机制。方法雄性10周SD大鼠36只,随机分为对照组、DAI 3 d组和DAI 3 d+TP组,每组12只。对照组仅麻醉,DAI 3 d组和DAI 3 d+TP组大鼠用瞬间旋转损伤装置建立DAI模型,DAI 3 d+TP组造模后5 min内腹腔注射TP(0.2 mg/kg),间隔24 h,连续3 d给药。HE染色评估各组大鼠皮层内的病理改变,免疫组化检测轴索损伤标志物tau、neurofilament-L、星型胶质细胞标志物GFAP、小胶质细胞标志物Iba-1及炎性因子TNF-α的表达;TUNEL检测细胞凋亡;Western blot检测皮层内NF-κB表达变化及p38 MAPK的磷酸化情况。结果与对照组相比,DAI 3 d组大鼠脑皮层内神经元肿胀、扭曲,轴索损伤标志物neurofilament-L表达增加,tau含量减少,而星型胶质细胞标志物GFAP、小胶质细胞标志物Iba-1、TNF-α、NF-κB的表达及p38 MAPK的磷酸化水平均升高,细胞凋亡增加(P<0.05);与DAI 3 d组相比,DAI 3 d+TP组大鼠脑皮层内神经元肿胀、扭曲减轻,neurofilament-L的表达减少,tau含量增加,而GFAP、Iba-1、TNF-α、NF-κB的表达及p38 MAPK的磷酸化水平均下降,细胞凋亡数减少(P<0.05)。结论雷公藤甲素能减少DAI后促炎因子TNF-α的释放,抑制胶质反应,减轻继发性轴索损伤,其保护作用可能与阻断NF-κB及p38 MAPK途径有关。
Objective To study the protective effect of triptolide(TP) against diffuse axonal injury(DAI) in rats,and explore its anti-inflammation effect on secondary brain injury after DAI. Methods Thirty-six 10-week-old SD male rats were randomly divided into control group,DAI 3 d group and DAI 3 d+TP group,with 12 rats in each group. The rats in control group only underwent anesthesia,while the models of DAI were established by lateral head-rotation device in DAI 3 d group and DAI 3 d+TP group. The rats were intraperitoneally injected with TP(0.2 mg/kg) within 5 min after injury every 24 h for 3 consecutive days in DAI 3 d+TP group. The pathological changes of rat cortex were assessed 3 d after DAI by HE. The expression of axonal injury markers(tau,neurofilament-L),GFAP,Iba-1 and pro-inflammatory factor(TNF-α) was detected by immunohistochemistry. Cell apoptosis was detected by TUNEL. The expression of NF-κB and the phosphorylation of p38 MAPK were accessed by Western blot. Results Compared to control group,the swelling and distortion of neurons was observed,the expression of tau was decreased,and the expression of neurofilament-L,GFAP,Iba-1,TNF-α,NF-κB,phosphorylation of p38 MAPK and the number of apoptosis cells in cortex were significantly increased in DAI 3 d group( P<0.05). Compared to DAI 3 d group,the swelling and distortion of neurons was attenuated,the expression of tau was increased,and the expression of neurofilament-L,GFAP,Iba-1,TNF-α,NF-κB,phosphorylation of p38 MAPK and the number of apoptosis cells in cortex were significantly decreased in DAI 3 d+TP group( P<0.05). Conclusion TP can reduce the release of inflammatory cytokine TNF-α,inhibit the glial response and protect from secondary axonal injury after DAI. The protective mechanism of TP might be related to the inhibition of NF-κB and p38 MAPK signal pathway.
Journal of Shanxi Medical University