Effects of prolonged kanamycin administration on cochlear anatomy and auditory brainstem response thresholds in chickens.
OBJECTIVE
To determine whether regenerated hair cells in the basilar papilla of chickens are resistant to kanamycin monosulfate damage.


METHODS
Randomized controlled trial.


METHODS
Ninety newly hatched Roman chickens.


METHODS
Chickens were injected with kanamycin monosulfate (200 mg/kg/d) for 10, 13, 17, 20, 25, or 30 days.


RESULTS
Scanning electron microscopy revealed that hair cells in the proximal 40% of the basilar papilla degenerated and disappeared after 10 days of kanamycin treatment. Following this, hair cell regeneration and repair was apparent. Regeneration and maturation of hair cells within 20 days in chickens that received treatment for 20 days were similar to those in chickens that were treated for 10 days followed by 10 days of recovery. After 25 days of treatment, many regenerated hair cells of mature appearance were reinjured. Regenerated hair cells of immature appearance were not damaged. The auditory brainstem response assay showed that the loss and recovery thresholds in chickens treated with kanamycin for 20 days were similar to those in chickens treated for 10 days followed by 10 days of recovery. There was a loss of auditory brainstem response thresholds in chickens that were treated with kanamycin for more than 20 days.


CONCLUSIONS
The immature regenerated hair cells in the basilar papilla of chickens are resistant to kanamycin ototoxic effects; however, this resistance is not seen in mature hair cells following prolonged kanamycin exposure.
Xiang
Ming-Liang
ML
Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665 Kong-Jiang Rd, Shanghai 200092, China. xiangming_liang@yahoo.com.cn
Wu
Hao
H
Huang
Qi
Q
Cheng
Lan
L
D000818:Animals; D000900:Anti-Bacterial Agents / Q000633:toxicity*; D001309:Auditory Threshold / Q000187:drug effects; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects*; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000473:pathology; D006319:Hearing Loss, Sensorineural / Q000139:chemically induced* / Q000503:physiopathology; D007612:Kanamycin / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D009410:Nerve Degeneration / Q000139:chemically induced / Q000473:pathology; D009416:Nerve Regeneration; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology; D011897:Random Allocation
D000900:Anti-Bacterial Agents; D007612:Kanamycin