延长卡那霉素外环境持续存在时间鸡基底乳头的超微形态变化

背景:卡那霉素延长施药时鸡听功能的变化已有少数文献报道,但关于其耳蜗超微形态变化的研究极少。目的:观察鸡耳中毒后卡那霉素外环境持续存在时鸡基底乳头的超微形态变化。设计:完全随机设计,对照观察。单位:上海第二医科大学附属新华医院。材料:实验于2001-06/2003-08在上海第二医科大学附属新华医院完成。选择新生罗曼鸡78只,雌雄不拘,由上海归兴种鸡厂提供。方法:将3d龄罗曼雏鸡连续肌注卡那霉素200mg/(kg·d)10d后随机分组:①经典施药组:不再施与药物,分别于施药完毕后1,3,7,10,15d时处死,每时相组6只。②延长施药组:继续按200mg/(kg·d)肌注卡那霉素,分别于连续施药13,17,20,25,30d时处死,每时相组6只。③对照组:不施与任何药物。设3,13,33d龄3组,每时相组6只。处死时分别与初次施药开始时、连续施药10d及30d的实验动物同龄。各时相组分别行听性脑干反应检测及基底乳头扫描电镜观察,观察耳蜗超微形态变化、阈值、阈值时Ⅰ波潜伏期及振幅变化。主要观察指标:①鸡耳蜗超微形态变化。②鸡听性脑干反应检测结果。结果:78只罗曼鸡全部进入结果分析,无脱失。①听性脑干反应检测结果:连续施药20d内,鸡听性脑干反应阈值损失及恢复与施药10d即停药组非常相似;施药20d后,鸡听性脑干反应阈值再次明显升高。②扫描电镜结果:对鸡施与卡那霉素10d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20d内基底乳头再生毛细胞之发育成熟与施药10d即停药组基本一致;连续施药25d时,基底乳头近半端部分再生毛细胞再次受损,连续施药30d时,大部分再生毛细胞破坏消失。结论:鸡卡那霉素耳中毒后,卡那霉素的持续存在明显阻止了鸡基底乳头损伤的完全修复。

Ultrastructural change of chicken basilar papilla during a prolonged administration of kanamycin

BACKGROUND: Although some studies have been done on the functional change of cochlea in chickens during prolonged administration of kanamycin,few studies on ultrastructural changes in chicken cochlea have been reported.OBJECTIVE: To observe ultrastructural changes of the chicken basilar papilla following poisoning with prolonged administration of kanamycin.DESIGN: A completely randomized design and controlled observation.SETTING: Affiliated Xinhua Hospital, Shanghai Second Medical University.MATERIALS:The experiment was conducted in Xinhua Hospital Affiliated to Medical College, Shanghai Jiao Tong University from June 2001 to August 2003. Newly born Roman chickens (n=78), of either sex, provided by Shanghai Guixing Breeding Chick Farm, were used as subjects.METHODS: 200 mg/kg kanamycin was injected into muscles daily at day 3 after birth for 10 days. Then they were divided into 3 groups randomly:①typical application group: The chickens were applied with drugs no longer, and then killed at days 1, 3,7, 10 and 15, 6 chickens in each time phase. ②prolonged application group: 200 mg/kg kanamycin per day were injected into muscles continuously, and then killed at days 13, 17, 20, 25and 30, 6 chickens in each time phase. ③control group: The chickens were not treated with any drug. They were assigned into 3, 13 and 33 days groups with 6 chickens in each time phase. When the chickens were killed they were at the same age with the experime ntal animals at days 0, 10 and 30 of kanamycin treatment. All the experimental animals were studied with auditory brain-stem response (ABR) and scanning electron microscopy in chicken basilar papilla to observe ultrastructural change of cochlea, threshold, latency and amplitude of ABR wave I.MAIN OUTCOME MEASURES: ①Ultrastructural change of the chicken basilar papilla, and ② ABR result of chicken.RESULTS: A total of 78 Roman chickens were involved in the result analysis, without dropout. ①Outcome of ABR: Loss and recovery of chicken ABR threshold value was similar between within continuous administration for 20 days and administration for 10 days plus 10 days of recovery (drug withdrawal group). Twenty days after administration, ABR threshold significantly increased again. ②Outcome of scanning electron microscopy: At the end of 10-day kanamycin administration, hair cells in 40％ proximal chicken basilar papilla were destroyedand disappeared completely. Although continuous administration was performed, the hair cells began to regenerate and repair after damage. Within the 20-day continuous administration, the regenerated hair cells of basilar papilla developed maturity, which was mostly coincident with the administration for 10 days group. At day 25, regenerated hair cells of proximal basilar papilla were injured once again. At day 30, most of the regenerated hair cells were destroyed and disappeared.CONCLUSION: Prolonged administration of kanamycin obviously prevents the full repair of chicken basilar papilla damaged by kanamycin poisoning.