摘要背景 研究证实绿茶提取物表没食子儿茶素没食子酸酯(EGCG)全身应用可到达视神经及视网膜组织,对视网膜缺血-再灌注和视神经钳夹伤后视网膜神经节细胞(RGCs)具有保护作用,但EGCG对视神经损伤后RGCs上位神经元的影响目前尚未见报道.目的 探讨EGCG对大鼠视神经钳夹伤后外侧膝状体(LGN)神经元的保护作用.方法 48只Wistar大鼠按随机数字表法分为正常对照组、假手术+EGCG组、视神经钳夹+生理盐水组、视神经钳夹+EGCG组,每组12只.用40g微型视神经夹于大鼠右眼球后约2mm处夹持视神经60s建立视神经钳夹伤模型,假手术+EGCG组、视神经钳夹+EGCG组大鼠于造模前2d始每日腹腔内注射EGCG(25mg/kg)共5d,后改为口服(2mg/kg),视神经钳夹+生理盐水组大鼠以同样的方法注射生理盐水.于造模4周后处死大鼠并取脑组织,用Nissl染色法计数外侧膝状体背侧核(dLGN)神经元数目,用免疫组织化学染色法和Western blot法观察神经丝蛋白(NF-L)在LGN的表达,比较各组大鼠dLGN中神经型一氧化氮合酶(nNOS)免疫组织化学染色阳性细胞数量.结果 视神经钳夹伤后4周,假手术+EGCG组左侧、右侧dLGN神经元数量与正常对照组相比差异无统计学意义(P=0.906、P=0.561);视神经钳夹+生理盐水组、视神经钳夹+EGCG组钳夹同侧dLGN神经元数量与正常对照组相比,差异无统计学意义(P=0.794、P=0.646),对侧dLGN神经元数量均低于正常对照组(P=0.000、P=0.015),而视神经钳夹+EGCG组钳夹对侧dLGN神经元数量高于视神经钳夹+生理盐水组(P=0.007);NF-L检测可见视神经钳夹+EGCG组钳夹对侧LGN的NF-L表达量高于视神经钳夹+生理盐水组(P=0.002);dLGN的nNOS阳性细胞计数在正常对照组、假手术+EGCG组、视神经钳夹+EGCG组之间差异无统计学意义(P>0.05),而视神经钳夹+生理盐水组钳夹对侧dLGN的nNOS阳性细胞高于视神经钳夹+EGCG组(P=0.000).结论 EGCG对大鼠视神经钳夹伤后LGN的神经元可能具有一定的保护作用,这种保护作用可能与EGCG抑制了nNOS的表达有关.

abstractsBackground Researches demonstrated that epigallocatechin-3-gallate(EGCG) can protect retinal ganglion cells(RGCs) against damage induced by retinal ischemia-reperfusion and optic nerve crush(ONC),but the effect of EGCG on lateral geniculate nucleus(LGN) was under study.Objective This study was designed to detect neuroprotective effect of EGCG on LGN in the rat model with ONC.Methods Forty-eight 7-week-old female clean Wistar rats were randomly divided into normal control group,sham operation+EGCG group,ONC+normal saline(NS) group and ONC+EGCG group.ONC models were created by clamping the optical nerve for 60 seconds with the clipper with the force of 40 grams in the right eyes of 24 rats.The EGCG solution(25mg/kg) was intraperitoneally injected from 2 days before operation daily for 5 consecutively days and orally administered(2mg/kg) after that,and NS was used in the same way for ONC+NS group.Four weeks after ONC,the brain tissue of the rats was obtained,and the neurons of dorsal LGN(dLGN) were counted by Nissl staining under the light microscopy.The expression of neurofilament triplet L(NF-L) was detected by immunohistochemistry and Western blot analysis.Meanwhile,the neuronal nitric oxide synthase(nNOS) positive cells were counted.Results Compared with normal control group,no significant differences were found in neuron number both between sham operation+EGCG group or ipsilateral LGN of operative eyes in ONC+normal saline group and ONC+EGCG group(P=0.906,0.561,0.794,0.646 respectively) in 4 weeks after ONC,but loss of neurons in contralateral LGN in both ONC+normal saline group and ONC+EGCG group were observed(P=0.000,0.015 respectively).However,compared with ONC+normal saline group,the density of neurons in ONC+EGCG group was higher(P=0.007).Moreover,a higher expression level of NF-L protein was seen in ONC+EGCG group compared with ONC+normal saline group at contralateral LGN of operative eyes(P=0.002).Concerning the number of nNOS positive cells in LGN,there was no significant difference among normal control group,sham operation+EGCG group and ONC+EGCG group(P＞0.05).The number of nNOS positive cells in the contralateral LGN of operative eyes of ONC+normal saline group was higher than that of ONC+EGCG group(P=0.000).Conclusion EGCG plays the protective effect on LGN after ONC in rats through mediating the expression of nNOS.