儿茶素对SD大鼠卡那霉素耳神经毒性保护作用的形态学研究

Morphologic studies of the protective role of catechin on kanamycin otoneurotoxicity in SD rats

目的 :动态观察卡那霉素 (kanamycin ,KM)中毒及应用儿茶素 (catechin ,CC)后耳蜗传出神经元及毛细胞的形态学改变 ,探讨氨基糖甙类抗生素 (aminoglycosideantibiotics ,AmAn)耳毒性中儿茶素对耳蜗传出神经元和毛细胞的保护作用。方法 :将 38只SD雄性大鼠随机分成 4组 :①卡那霉素组 (KM组 ) 10只 ,5 0 0mg·(kg·d) - 1 ,②儿茶素灌胃组(CC组 ) 10只 ,80 0mg·(kg·d) - 1 ,③KM +CC组 (KC组—儿茶素保护组 ) 10只 ,④生理盐水对照组 10只。电镜动态观察耳蜗传出神经纤维末梢及毛细胞亚细胞结构的改变及采用全耳蜗铺片改良的乙酰胆碱酯酶染色法观察耳蜗传出神经纤维及末梢的数量。结果 :电镜显示儿茶素保护组传出神经元及毛细胞损伤较未保护组明显减轻 ,儿茶素组和生理盐水组无损伤表现。乙酰胆碱酯酶组化染色示KM组耳蜗传出神经数量较KC组及其他对照组明显减少 (P <0 .0 5 ) ,儿茶素保护组与儿茶素组及正常对照组比较无明显差异 (P >0 .0 5 )。结论

Objective To determine the protection of catechin on aminoglycoside antibiotics otoneurotoxicity in SD rats, and observe the morphologic changes of cochlear efferent nerve terminals and outer hair cells after the injection of kanamycin and the feeding of catechin by the stomach tube. Methods Thirty eight SD rats were randomly assigned into three experimental groups (KM treated, catechin treated, KM and catechin in combination) and one control group. The KM treated group was given kanamycin in a dose of 500 mg·(kg·d) -1 for 14 days. The catechin treated group was given catechin once by the stomach tube in a dose of 400 mg·(kg·d) -1 . Two kinds of medicine were simultaneously given in the KM+catechin group. Transmission electron microscopy was utilized to observe the subcellular structure of efferent nerve fibers and outer hair cells. The densities of efferent nerve fibers and terminals were examined and the numbers of efferent nerve fibers and terminals were numerated by the surface preparation using modified histochemical staining for acetylcholinesterase (AchE). Results The damage in the group protected by catechin was relieved compared with the unprotected group. No damage was found in the catechin treated alone group and controls. The densities and numbers of efferent nerve fibers and terminals were obviously fewer in the unprotected group than in the protected group and controls(P<0.05). There was no significant difference in the numbers of efferent nerve fibers and terminals of the group protected by catechin compared with the controls and the catechin treated group (P>0.05). Conclusion Catechin significantly protects MOC efferent nerves in kanamycin otoneurotoxicity.