表没食子儿茶素没食子酸酯对噪声性耳蜗损伤的影响

目的 探讨表没食子儿茶素没食子酸酯(epigallocatechin-3-gallate,EGCG)对噪声性耳蜗损伤的影响.方法 45只豚鼠随机分为EGCG+噪声组、生理盐水+噪声组、正常对照组,每组15只.EGCG+噪声组和生理盐水+噪声组豚鼠在接受噪声暴露(120 dB SPL, 4 h)前一日及每次暴露前1 h分别腹腔注射EGCG(25 mg/1 000 g)和等量生理盐水,正常对照组不予任何处理.噪声暴露后即刻和第1、3、7、14天检测三组豚鼠听性脑干反应(ABR),第14天分离各组豚鼠耳蜗,行耳蜗基底膜、血管纹铺片及免疫组化染色,观察各组豚鼠耳蜗基底膜、血管纹细胞形态及外毛细胞运动蛋白(Prestin)、3-硝基酪氨酸(3-NT)分布的变化.结果 噪声暴露后,EGCG+噪声组各时间点的ABR反应阈均高于对照组,但低于生理盐水+噪声组,从第3天开始,与两组间ABR反应阈差异缩小,但差异仍有统计学意义(均为P<0.05).免疫组织化学染色显示,正常对照组Prestin蛋白显绿染的耳蜗三排外毛细胞排列整齐,无细胞缺失,3-NT主要分布于毛细胞胞质及表皮板;与生理盐水+噪声组相比,噪声暴露后,EGCG+噪声组豚鼠外毛细胞形态较好,Prestin染色清晰;基底膜、血管纹处损伤轻,细胞排列规则,3-NT分布减少.结论 预防性腹腔注射EGCG可减轻噪声引起的耳蜗损伤,对噪声性听力损伤有一定的防护作用.

The Effects of Epigallocatechin-3-gallate(EGCG) on Noise-Induced Cochlear Injury

Objective To study the effects of epigallocatechin-3-gallate(EGCG) on noise-induced cochlear injuries.Methods A total of 45 guinea pigs were divided into three groups: the EGCG+noise exposure group, the normal saline+noise exposure group, and the control group.15 Guinea pigs in each group.For EGCG administration, the guinea pigs were given abdominal injection (25 mg/1 000 g) 1 day before and 1 hour before noise exposure (120 dB SPL, 4 h),where for the control group, the guinea pigs received nothing.The hearing function was detected by the auditory brainstem response (ABR) recording after noise exposure immediately, and at 1,3,7, and 14 days after noise exposure.On the 14th day, the cochlea were isolated, and the cells morphology of basal membrane and vascular stria, the outer hair cell movement protein (Prestin), and the 3-nitrotyrosine (3-NT) were examined by immunohistochemistry staminy.Results After noise exposure, ABR thresholds in the EGCG group were higher than that of in the control group(P<0.05), but lower than the normal saline group(P<0.05),though the differences between the other two groups became smaller from day 3.Immunohistochemistry (IHC) staining showed that the three rows of outer hair cells of the control group with Prestin protein stained were arranged neatlyand lack of cell absent, and 3-NT was mainly distributed in the cytoplasm and epidermis.Compared with the normal saline + noise group, after noise exposure, the outer hair cells of EGCG + noise group were in better shape, and prestin staining was clear.Besides, the basal membrane and vascular stria were slightly damaged, the cells arranged neatly and the 3-NT distribution was decreased.Conclusion Preventive intraperitoneal injection of EGCG may reduce cochlea damage caused by noise.