The Effects of Epigallocatechin-3-gallate(EGCG) on Noise-Induced Cochlear Injury / 听力学及言语疾病杂志

ABSTRACT

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.