苯扎托品对大鼠非动脉炎性前部缺血性视神经病变模型神经保护作用初探

Neuroprotective effects of benzatropine on rat model of nonarteritic anterior ischemic optic neuropathy

目的观察并初步探讨苯扎托品对大鼠非动脉炎性前部缺血性视神经病变(rNAION)模型RGC死亡及视神经损伤的保护作用。方法Sprague-Dawley大鼠25只,以右眼为实验眼。采用光动力方法建立rNAION模型并随机分为苯扎托品干预组和PBS对照组,分别为13、12只大鼠;左眼为正常对照组。大鼠按体重10 mg/kg的剂量腹腔注射苯扎托品溶液0.2 ml,PBS对照组大鼠腹腔注射等体积PBS;1次/d,连续21 d。建模后1、3、7 d直接检眼镜检查观察大鼠视盘改变。建模后28 d,透射电子显微镜观察三组大鼠视神经髓鞘、轴突损伤情况;经上丘荧光金逆行标记及荧光显微镜照相,观察苯扎托品干预组和PBS对照组大鼠RGC密度,计算RGC存活率。两组大鼠RGC密度及存活率比较采用单因素方差分析。结果建模后1、3 d,rNAION模型组大鼠视盘水肿,边界欠清晰;建模后7 d,视盘水肿较建模后3 d时减退,边界模糊。建模后28 d,荧光显微镜观察发现,苯扎托品干预组、PBS对照组大鼠RGC密度分别为(1173±868)、(308± 194)个/mm^2;两组间差异有统计学意义(F=7.552,P=0.015)。RGC存活率分别为47.6%、13.7%;两组间差异有统计学意义(F=8.184,P=0.012)。透射电子显微镜观察发现,正常对照组大鼠视神经纤维束结构完整,可见大小不等的轴突规则排列,髓鞘明显。PBS对照组大鼠视神经髓鞘解体,轴突消失,可见"洋葱样"小体、胶质增生;苯扎托品干预组大鼠多数轴突和髓鞘结构基本完整,破坏程度较PBS组明显减轻。结论苯扎托品干预组大鼠RGC存活率和视神经轴突、髓鞘破坏较对照组明显改善,具有潜在的神经保护价值。

Objective To investigate the neuroprotective effect of Benztropine on retinal ganglion cells(RGCs) death and optic nerve injury in rats model of non-arteritis anterior ischemic optic neuropathy (rNAION). Methods A total of 25 Sprague-Dawley rats were randomly divided into Benztropine treatment group (n=13) and PBS control group (n=12). The right eye was set as the experimental eye. rNAION model was established by using rose Bengal combined with laser photodynamic method. The rats in the Benztropine treatment group were received intraperitoneal injection with Benztropine 10 mg/kg (0.2 ml) daily for 3 weeks, while the rats in the PBS control group were received intraperitoneal injection with an equal volume of PBS. At 1, 3 and 7 days after modeling, the retinal and optic disc conditions of the rats were observed by direct ophthalmoscopy. Retrograde labeling, fluorescence microscopy and transmission electron microscopy were used to observe the survival of RGCs and the damage of the optic nerve myelin and axon at 4 weeks after modeling. The RGCs density and survival rate of the two groups were compared by One-Way Anova. Results At 1 and 3 days after modeling, the optic disc edema was observed in the rats of rNAION model group. At 7 days after modeling, the optic disc edema decreased and the boundary was blurred compared with 3 days after modeling.After 4 weeks, the RGCs density in the PBS group was 308±194/mm2 and the survival rate was 13.7%. The density of RGCs in the Benztropine group was 1173+868/mm2 and the survival rate was 47.6%. The differences of RGCs density and survival rate were significant between the two groups (F=7.552, 8.184;P=0.015, 0.012). Myelin disintegration, axon degeneration, onion-like body and gliosis were observed in the optic nerve sections of rNIAON in the PBS group, while the damage of axon and myelin structure in the Benztropine group was significantly less than that in the PBS group. Conclusions Benztropine group showed higher RGC survival rate, less damage of axon and myelin structure on rNAION model. This study explored the potential neuroprotective effect of Benztropine.