表没食子儿茶素没食子酸酯对大鼠视神经钳夹伤后视网膜神经节细胞的保护作用

Neuroprotective effect of epigallocatechin-3-gallate on retinal ganglion cells in optic nerve crush rat model

目的 观察绿茶提取物表没食子儿茶素没食子酸酯（EGCG）对大鼠视神经钳夹伤视网膜神经节细胞（RGC）是否具有保护作用.方法 72只Wistar大鼠随机分为正常对照组（A组）、假手术＋EGCG组（B组）、视神经钳夹＋生理盐水组（C组）、视神经钳夹＋EGCG组（D组）等4组,每组各18只.B、D组在视神经钳夹或假手术前2 d起给予腹腔注射EGCG 25 mg/（kg·d）,直至手术后2 d,共5 d;随后改为口服2 mg/（kg·d）.C组以生理盐水替代EGCG.每次每组取6只大鼠,采用3%荧光金经上丘逆行标记RGC方法 ,比较各组视神经钳夹伤后7、14、28 d RGC的存活数量;采用免疫组织化学染色及蛋白免疫印迹方法 检测各组视神经组织神经丝蛋白（NF-L）的表达.结果 视神经钳夹伤后7 d,C、D组RGC存活数量分别为（943.61±85.06）、（1 134.45±117.85）个/mm2;14 d时分别为（812.76±172.07）、（1 021.67±94.02）个/mm2;28 d时分别为（766.94±171.45）、（1 009.72±126.40）个/mm2.各时间点D组RGC存活数量均显著高于C组（t=3.216,2.609,2.792;P=0.009,0.026,0.019）.各时间点A、B组间RGC存活数量差异无统计学意义（t=0.749,0.403,0.254;P值均＞0.05）;视神经钳夹后7、14、28 d,D组视神经组织NF-L表达均高于C组（t=9.847,5.731,2.868;P=0.001,0.005,0.045）.结论 EGCG对大鼠视神经钳夹伤后RGC具有一定的保护作用.

Objective To investigate the neuroprotective effect of epigallocatechin-gallate （EGCG）,the major catechin found in green tea, in an optic nerve crush （ONC） rat model. Methods Seventy-two Wistar rats were divided randomly into four groups： normal control, sham-operation＋ EGCG, ONC＋vehicle, and ONC＋ EGCG groups. Animals were treated intraperitoneally and orally with either vehicle （normal saline） or EGCG （25 mg/kg, injected daily for up to five days, and orally 2 mg/kg daily afterwards）. Two days after the first injection, an ONC injury using a micro optic nerve clipper was performed at approximately 2 mm from the optic nerve head for 60 seconds. Fluorogold was injected into bilateral superior colliculi five days before sacrifice and fluorescent gold labeled retinal ganglion cells （RGC）were counted under fluorescence microscopy on days seven, 14 and 28 after optic nerve crush. Meanwhile,the expression of neurofilament triplet L （NF-L） was measured by immunohistochemistry and Western blotting. Results In the ONC ＋ vehicle group, a progressive loss of RGC was observed;however,compared with the ONC＋vehicle group, RGC density was significantly higher on day seven （t=3. 216, P=0. 009）, day 14 （t=2. 609, P=0. 026） and day 28 （t=2. 792, P=0. 019） , and a significant increase of theNF-L protein expression has been observed on days seven, 14 and 28 after optic nerve crush in the ONC＋EGCG group. Conclusions EGCG has a protective effect to the bodies and axons of the RGC after optic nerve crush.