Ultrastructural change of chicken basilar papilla during a prolonged administration of kanamycin / 中国组织工程研究

ABSTRACT

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.MATERIALSThe 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 randomly①typical 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.