卡那霉素耳中毒后雏鸡耳蜗神经纤维的透射电镜观察

摘要

Purpose To study the effects of kanamycin damage on the cochlear nerve fibers of bird.Methods Newly hatched chickens were recevied daily injection of kanarnycin for 10 consecutive days.Following auscultate brainstem response test, animals were killed on the eighth day of kanamycin injectionand 1,7, 10, 15, 21,30, 60 days after 10 days kanamycin treatment. The ultrastructural changes onmyelinated and nonmyelinated nerve in the proximal portion of the basilar papilla were studied by usingtransmission electron microscope. Results The experimental animals' hearing began recovering in a fewdays and arrived at a stable level in 10 days after the completion of drug injection. There were no obviousultrastructural changes on myelinated and nonmyelinated nerves in kanamycin treated groups. Conclusionsrn Transmission electron microscope study showed that the cochlear nerve fibers of the chicken had not beendamaged by kanamycin, and the undamaged nerve fibre may be helpful for the regenerated hair cell to getreirnervation and therefor recover chicken's hearing function.%目的 探讨卡那霉素对鸟类耳蜗神经纤维有无损伤。方法 将雏鸡连续肌注卡那霉素10 d[2O0 mg/(kg·d)]，分别于施药8 d、药毕1、7、10、15、21、30、60 d时行听性脑干反应测听(ABR)检查，完毕后随即处死，采用透射电镜观察其耳蜗神经纤维形态结构变化。结果 ABR检查显示，小鸡听功能于停药后即很快开始恢复，至药毕10 d时已基本稳定。透射电镜观察，施药8 d时，基底乳头近端20％区域的毛细胞已被卡那霉素完全破坏，损伤区域的无髓和有髓神经纤维均无明显损伤征象，施药10 d毕后所有观察时间点里，神经纤维的形态结构同样未见明显异常。结论 卡那霉素对雏鸡耳蜗神经纤维无明显毒性作用。耳蜗神经纤维的未受损可能有助于再生毛细胞极早获得神经再支配及听功能的迅速恢复。