噪声预暴露对强声致豚鼠听力损伤及热休克蛋白70表达的影响

目的研究噪声预暴露在强噪声所致豚鼠听力损伤中的保护作用以及内耳毛细胞内热休克蛋白 70 (HSP70 )的表达。方法体重 2 5 0～ 30 0g健康杂色、耳廓反应正常豚鼠 4 0只 ,随机分为正常对照组 ,噪声预暴露组 ,强噪声暴露组 ,噪声预暴露 +强噪声暴露组。所用预暴露噪声为 95dBSPL、6h× 10d ,强噪声暴露为 110dBSPL、2h。应用听性脑干反应 (ABR)测听、基底膜铺片和免疫组化方法分别检测听阈位移、毛细胞缺失率和HSP70在毛细胞的表达。结果与单纯强噪声暴露组相比 ,噪声预暴露 +强噪声暴露组听阈位移以及毛细胞缺失率均显著降低 ,其中第 3排外毛细胞缺失率降低 2 4 .8% (P <0 .0 5 ) ,处理后第 6天听阈位移降低 6 7.9% (P <0 .0 1) ;与正常对照组相比 ,声暴露后HSP70在毛细胞表达均显著增加 (P <0 .0 5 ) ,以预暴露后强噪声暴露组表达最强 ,但预暴露组和单纯强噪声暴露组毛细胞HSP70的表达量无显著差别。结论适当的噪声预暴露能够减轻高强度噪声所致内耳毛细胞损伤 ,对听觉系统有一定的保护作用 ;噪声暴露诱导内耳毛细胞HSP70的高表达 ,可能是噪声预暴露保护效应机制之一

EFFECTS OF SOUND CONDITIONING ON HIGH INTENSITY NOISE-INDUCED HEARING LOSS AND EXPRESSION OF HEATSHOCK PROTEIN 70 IN GUINEA PIGS

Objective To study the protective effects of sound conditioning on hearing loss and expression of HSP70 induced by high intensity noise in guinea pigs. Methods Forty healthy guinea pigs with normal Preyer's reflex were used in the study.The animals were divided into four groups: normal group(NG) ,conditioning noise group(CG,95dB SPL) ,high intensity noise group(HG,110dB SPL) and conditioning noise plus high intensity noise group(CG+HG). Hearing threshold was tested with auditory brainstem response (ABR). The rate of hair cell loss was measured with surface preparation technique in morphological aspect, and immunohistochemistry study of the Corti's organs were carried out with HSP70 monoclonal antibody. Results Conditioning sound exposure could reduce the threshold shift and the loss rate of hair cell induced by afterwards high intensive noise. The hearing threshold shift was 67.9% less in CG+HG group than in HG group (P<0.01)on day 6, and the loss rate of the 3 rd roll outer hair cell was 24.8% less in CG+HG group than in HG group (P<0.05). The expression of HSP70 of the hair cells in CG,CG+HG and HG animals were significantly higher than that in NG group and was the highest in CG+HG group, but there was no remarkable difference between CG and HG groups. Conclusion Proper intensity sound conditioning can protect the auditory system of guinea pigs from injury induced by high intensity noise to a certain extent , and HSP70 may play a role in the protective effect.