卡那霉素延长给药时鸡基底乳头的损伤与修复

Anatomical and Functional Recovery in Avian Cochlea following Prolonged Administ ration of Kanamycin

目的 了解卡那霉素延长给药时鸡基底乳头的超微形态变化。方法 将 3天龄罗曼雏鸡连续肌注卡那霉素 (2 0 0mg·kg- 1·d- 1) 10天后随机分组 :①经典施药组 :不再注射药物 ,于药毕后 1、3、7、10、15天时行ABR检测及基底乳头扫描电镜观察。②延长施药组 :继续肌注卡那霉素 ,于连续施药 13、17、2 0、2 5、3 0天时行ABR检测和基底乳头扫描电镜观察。结果 ABR检测结果显示 ,连续施药 2 0天内 ,鸡ABR阈值损失及恢复不受卡那霉素影响 ,与施药 10天即停药者非常相似 ;施药 2 0天后 ,鸡ABR阈值则再次明显升高。扫描电镜观察 :将鸡施与卡那霉素 10天完毕时 ,鸡基底乳头近端 40 %区域毛细胞完全破坏消失 ;其后虽继续施药 ,毛细胞已开始再生修复损伤 ,连续施药 2 0天内基底乳头再生毛细胞无明显受损 ,其形态发育与施药 10天即停药者基本相似 ;连续施药 2 5天时 ,则有部分再生毛细胞出现受损 ,连续施药 3 0天时 ,大部分再生毛细胞破坏消失。结论 鸡卡那霉素耳中毒后 。

Objective To study whether anatomical and functional recovery in avian cochlea following ototoxicity is suppressed by the prolonged treatment of kanamycin. Methods One group of newly hatched chicks were given intramuscular injection of kanamycin monosulfate (200 mg·kg -1 ·d -1 ) for 10 consecutive days and tested with ABR 1,3,7,10,15 days following the completion of drug treatment, while another group of chickens received kanamycin injection for 13,17,20,25,30 consecutive days and were tested with ABR at the time of drug termination. After ABR measurement, animals were sacrificed immediately and their cochlea were studied by scanning electron microscopy. Results ABR measurement showed that thresholds from the animals received kanamycin for 20 days was similar to those from the animals received 10 days of kanamycin plus 10 days of recovery. From the animals that received kanamycin treatment for more than 20 days, however, came the tendency of hearing function loss again. The thresholds measured from the animals received kanamycin treatment for 30 days were significantly higher than those measured from the animals received drug for 20 days. Scanning electron microscopy study showed that the morphological maturation of regenerated hair cells in the basilar papilla of chicks received kanamycin for 20 days was similar to those from the animals received 10 days of kanamycin plus 10 days of recovery. After 25 days of kanamycin treatment, however, many mature regenerated hair cells were injured again. The degenerated appearance of the basilar papilla from the animal treated with kanamycin for 30 days was more evident than that for 25 days, and the majority of regenerated hair cells was destroyed completely. Conclusion The prolonged administration of kanamycin is harmful to anatomical and functional restoration in avian cochlea following kanamycin ototoxicity.