卡那霉素再次耳中毒后听功能变化的实验研究

背景鸡卡那霉素初次耳中毒后其内耳的功能及形态变化已有较多研究,有关再次耳中毒后听功能的变化目前报道尚少.目的探讨鸡卡那霉素再次耳中毒后听功能的损伤及恢复.设计完全随机设计.地点和材料本实验完成于上海第二医科大学新华医院.所用动物为新生罗曼鸡.干预将雏鸡于初次耳中毒后16 d开始再次每天肌注卡那霉素(200mg/kg),共10 d.主要观察指标于再次药毕后1,7,10,15 d进行听脑干反应(auditorybrain-stem response,ABR)检测,观察其阈值、阈值时Ⅰ波潜伏期和振幅变化.结果首次耳中毒时,小鸡听功能损失于药毕时达到极限.停药后即迅速开始恢复,药毕7 d时,鸡ABR阈值有明显下降,药毕10 d时,ABR阈值恢复稳定.再次施药10 d完毕时,小鸡ABR阈值再次明显升高,但其程度较初次损伤时为轻(107.14 vs 116.32),药毕后鸡听功能恢复更快,再次药毕7 d时鸡ABR阈值已恢复稳定,与再次药毕1 d时相比,差异有非常显著性意义(P＜0.01),此后鸡ABR阈值未见明显变化.结论鸡卡那霉素再次耳中毒时,其听功能损失程度较初次损伤时为轻,恢复速度亦较初次损伤时为快.结果提示鸡卡那霉素初次耳中毒后,其基底乳头对卡那霉素的再次损伤具有一定程度的抵抗力.

Hearing function recovery following repeated kanamycin administration

BACKGROUND: Many studies have been done on the functional and morphological changes of the cochlea following primary poisoning with kanamycin in chicks. However, relatively few studies on the functional recovery of the avian cochlea after a second dose of kanamycin poisoning have been reported.OBJECTIVE: To study functional recovery of the avian cochlea after a second dose of kanamycin poisoning in chick.DESIGN: A completely randomized study was conducted.SETTING and MATERIALS: The experiment was completed in Xinhua Hospital, Shanghai Second Medical University. The animals were newly hatched Roman chickens.INTERVENTIONS: The newly hatched Roman chicks for the experiment were treated with kanamycin monosulfate(200 mg/kg per day) again for 10 consecutive days beginning on 16th day after completion of the initial course.MAIN OUTCOME MEASURES: The test for auditory brain-stem response ABR was performed 1, 7, 10, and 15 days following the first and second doses, respectively. Thresholds, latent period and amplitude of Ⅰ wave at thresholds were observed.RESULTS: The greatest thresholds shifted in the chicks at the end of the first 10-day course of kanamycin injection. The hearing function of the animals began to recover in a few days and remained stable within 10 days after drug administration. The thresholds measured at day 7 were significantly better than those measured at day 1 after drug cessation, and repeated at day 10 were better than at day 7. When the animals were treated with kanamycin again for 10 days beginning on the 1Ch day after completion of the initial course, thresholds shifted, but less than during the first dose period(107. 14vs 116. 32, P ＜ 0.01) . Hearing began to recover after a few days and remained stable by 7th day after completion of the second 10-day kanamycin treatment. Then, there were no significant changes in ABR thresholds CONCLUSION: The functional loss of hearing in the avian cochlea is less and recovery is faster following poisoning from the second dose of kanamycin. The results suggest that chickens may be less susceptible to the ototoxic effects of repeated kanamycin treatments.