EGCG对阿米卡星诱导大鼠螺旋神经元诱导型一氧化氮合酶表达的影响

目的探讨表没食子儿茶素没食子酸酯［(-)-epigallocatechin-3-gallate，EGCG］对阿米卡星（amikacin，Amk）诱导的大鼠耳蜗螺旋神经元(spiral ganglion neuron；SGN) 诱导型一氧化氮合酶（inducible nitric oxide synthase, iNOS）表达的影响。方法将30只SD大鼠分为生理盐水对照组、Amk（450?mg/kg·d×14d）损伤组和Amk加EGCG（50?mg/kg·d×14d）保护组。各组动物均经深度麻醉后，半身灌注固定处死，取右侧耳蜗标本固定、脱钙、石蜡轴位包埋、轴位切片，近中轴位切片行iNOS免疫组化染色，光学显微镜下检测耳蜗SGN表达情况，并通过切片图像分析进行半定量处理比较。结果对照组SGN胞浆及细胞核基本上不着色（SGN iNOS染色平均灰度值为111.04±3.15），损伤组SGN部分神经元胞浆内有棕黄色或黄色颗粒或斑片（SGN iNOS染色平均灰度值为90.32±5.26），保护组胞浆及细胞核无明显着色（SGN iNOS染色平均灰度值为109.35±4.89），图像分析结果显示，损伤组与对照组、损伤组与保护组之间的SGN iNOS染色平均灰度值差异有统计学意义。结论iNOS参与Amk耳中毒时耳蜗螺旋神经元的氧化损伤，EGCG可以减弱Amk耳中毒时耳蜗螺旋神经元iNOS的表达，从而减轻Amk耳毒性。

(-)-epigallocatechin-3-gallate affects the expression of inducible nitric oxide synthase in spiral ganglion neuron of rats induced by amikacin

To study the expression of iNOS in amikacin(Amk)-induced spiral ganglion neuron(SGN) apoptosis in the rat cochlea and the protection of (-)-epigallocatechin-3-gallate(EGCG). MethodsAnimals were divided into three groups: one group serving as the saline control group, one group receiving Amk at 450mg/kg once a day for 14 days, and one group receiving Amk plus EGCG at 50mg/kg once a day for 14 days. Following deep anesthesia, the animals were half-body perfused intracardially with 4% paraformaldehyde (PFD), and the bullas were harvested, fixed in PFD, and decalcified in ethylenediamine tetraacetic acid (EDTA). After decalcification, the cochlea were embedded in paraffin, and subsequently cut in a paramodiolar plane. Immunohistochemical changes were observed by detecting with iNOS. ResultsThe negative immunohistochemical reaction for iNOS-staining was found in the SGNs in the saline control group, and the positive reaction was found in the cytoplasm of part of the SGNs of the group receiving Amk. However, positive staining could hardly be detected in the group receiving Amk plus EGCG. Image analysis showed that the expression of iNOS was significantly up-regulated in the group receiving Amk, but this up-regulation was significantly suppressed by EGCG. ConclusionsiNOS was involved in Amk induced oxidative damages to the SGN in the rat cochlea. EGCG effectively attenuated Amk-induced ototoxicity and suppressed Amk-induced SGN apoptosis by the influence on the expression of iNOS.