埃博霉素D对大鼠外伤性视神经损伤的保护作用

Protective effect of Epothilone D against traumatic optic nerve injury in rats

目的探讨埃博霉素D治疗大鼠视神经损伤(TON)的治疗效果。方法42只健康SD大鼠分成埃博霉素D治疗组(1.0 mg/kg埃博霉素D腹腔注射)和等量DMSO溶剂对照组,3 d/次给药治疗直至28 d,首次给药次日建立大鼠TON模型。在3、7、28 d时运用活体闪光视觉诱发电位(FVEP)检测,免疫荧光检测,Western blot检测对两组大鼠视觉通路特性,视网膜神经节细胞(RGC)数量,受损轴突再生标志物蛋白GAP43表达水平,以及视网膜和视神经Tau及其pTau-396/404的变化情况进行研究。结果治疗组相对于对照组在3 d和28 d两个检测时间点中RGC的丢失率都显著下降(3 d下降19.12%,P=0.032;28 d下降22.67%,P=0.042),然而FVEP未能在治疗终点28 d时在生理上观测到视觉通路的改善(N2波潜伏期相对差异,P=0.236;P2-N2波振幅相对衰减差异,P=0.441)。视网膜中3 d时治疗组相对于对照组总Tau含显著增加(P<0.001),且总Tau和pTau-396/404的含量变化较一致;而在视神经轴突中,7 d时治疗组相对于对照组总Tau水平显著降低(P=0.002),但总Tau和pTau-396/404的变化关系不明显。此外,埃博霉素D的作用可使受损轴突在28 d时仍然表达GAP43。结论埃博霉素D对外伤性视神经损伤存在保护作用,其可促进损伤RGC的存活,增强存活RGC中胞体Tau的含量,降低受损轴突中Tau的累积,刺激受损轴突持续再生。

Objective To investigate the therapeutic effect of Epothilone D on traumatic optic neuropathy(TON)in rats.Methods Forty-two SD rats were randomized to receive intraperitoneal injection of 1.0 mg/kg Epothilone D or DMSO(control)every 3 days until day 28,and rat models of TON were established on the second day after the first administration.On days 3,7,and 28,examination of flash visual evoked potentials(FVEP),immunofluorescence staining and Western blotting were performed to examine the visual pathway features,number of retinal ganglion cells(RGCs),GAP43 expression level in damaged axons,and changes of Tau and pTau-396/404 in the retina and optic nerve.Results In Epothilone D treatment group,RGC loss rate was significantly decreased by 19.12%(P=0.032)on day 3 and by 22.67%(P=0.042)on day 28 as compared with the rats in the control group,but FVEP examination failed to show physiological improvement in the visual pathway on day 28 in terms of the relative latency of N2 wave(P=0.236)and relative amplitude attenuation of P2-N2 wave(P=0.441).The total Tau content in the retina of the treatment group was significantly increased compared with that in the control group on day 3(P<0.001),showing a consistent change with ptau-396/404 level.In the optic nerve axons,the total Tau level in the treatment group was significantly lower than that in the control group on day 7(P=0.002),but the changes of the total Tau and pTau-396/404 level did not show an obvious correlation.Epothilone D induced persistent expression of GAP43 in the damaged axons,detectable even on day 28 of the experiment.Conclusion Epothilone D treatment can protect against TON in rats by promoting the survival of injured RGCs,enhancing Tau content in the surviving RGCs,reducing Tau accumulation in injured axons,and stimulating sustained regeneration of axons.