Zuo Hongyan, Cui Bo, She Xiaojun, Wu Mingquan
Department of Occupational Hygiene, Institute of Health and Environmental Medicine of Tianjin, PR China.
J Occup Health. 2008;50(5):373-9. doi: 10.1539/joh.l8032. Epub 2008 Jul 25.
Sound conditioning has reduced noise-induced hearing loss in experimental mammalian animals and in clinical observation. Forty guinea pigs were grouped as: A, control; B, conditioning noise exposure group; C, high level noise exposure group; and D, conditioning noise exposure followed by a high level noise exposure group. Auditory brainstem response thresholds were measured. The cochlear sensory epithelia surface was observed microscopically. Calmodulin, F-actin and heat shock protein 70 (HSP70) in hair cells were immunohistochemistrically stained. The intracellular free calcium was stained for confocal microscopy. The ABR threshold shift after noise exposure was higher in group C than D, and showed a quicker and better recovery in group D than C. Stereocilia loss and the disarrangement of outer hair cells were observed, with the greatest changes seen in group C, followed by groups D and B. The most intensive immunohistochemical intracellular expressions of calmodulin, F-actin, and HSP70 were found in group D, followed by groups C, B and A. The highest intensity of the fluorescent intracellular free Ca2+ staining in the isolated outer hair cells was observed in group C. The ABR and morphological studies confirmed the protective effect from noise trauma of sound conditioning. The protective mechanism of hair cells during sound conditioning was enforced through the increase of cellular cytoskeleton proteins and through the relieving of intracellular calcium overloading caused by the traumatic noise.
声音预处理已在实验哺乳动物和临床观察中减少了噪声性听力损失。40只豚鼠被分为：A组，对照组；B组，预处理噪声暴露组；C组，高强度噪声暴露组；D组，预处理噪声暴露后再进行高强度噪声暴露组。测量听觉脑干反应阈值。显微镜下观察耳蜗感觉上皮表面。对毛细胞中的钙调蛋白、F-肌动蛋白和热休克蛋白70（HSP70）进行免疫组织化学染色。对细胞内游离钙进行染色以用于共聚焦显微镜观察。噪声暴露后C组的听性脑干反应阈值变化高于D组，且D组比C组恢复更快、更好。观察到静纤毛损失和外毛细胞排列紊乱，C组变化最大，其次是D组和B组。D组钙调蛋白、F-肌动蛋白和HSP70的免疫组织化学细胞内表达最强，其次是C组、B组和A组。在分离的外毛细胞中，C组观察到细胞内游离Ca2+荧光染色强度最高。听性脑干反应和形态学研究证实了声音预处理对噪声损伤的保护作用。声音预处理期间毛细胞的保护机制是通过增加细胞骨架蛋白以及减轻创伤性噪声引起的细胞内钙超载来实现的。
