[Morphologic studies of the protective role of catechin on kanamycin otoneurotoxicity in SD rats].
OBJECTIVE
To determine the protection of catechin on aminoglycoside antibiotics otoneurotoxicity in SD rats, and observe the morphologic changes of cochlear efferent nerve terminals and outer hair cells after the injection of kanamycin and the feeding of catechin by the stomach tube.


METHODS
Thirty-eight SD rats were randomly assigned into three experimental groups (KM-treated, catechin-treated, KM and catechin in combination) and one control group. The KM-treated group was given kanamycin in a dose of 500 mg.(kg.d)-1 for 14 days. The catechin-treated group was given catechin once by the stomach tube in a dose of 400 mg.(kg.d)-1. Two kinds of medicine were simultaneously given in the KM+ catechin group. Transmission electron microscopy was utilized to observe the subcellular structure of efferent nerve fibers and outer hair cells. The densities of efferent nerve fibers and terminals were examined and the numbers of efferent nerve fibers and terminals were numerated by the surface preparation using modified histochemical staining for acetylcholinesterase (AchE).


RESULTS
The damage in the group protected by catechin was relieved compared with the unprotected group. No damage was found in the catechin-treated alone group and controls. The densities and numbers of efferent nerve fibers and terminals were obviously fewer in the unprotected group than in the protected group and controls(P < 0.05). There was no significant difference in the numbers of efferent nerve fibers and terminals of the group protected by catechin compared with the controls and the catechin-treated group (P > 0.05).


CONCLUSIONS
Catechin significantly protects MOC efferent nerves in kanamycin otoneurotoxicity.
Liu
Guo-hui
GH
Department of Otorhinolaryngology, Second Xiangya Hospital, Central South University, Changsha 410011, China.
Xie
Ding-hua
DH
Wu
Wei-jing
WJ
D000818:Animals; D000975:Antioxidants; D002392:Catechin / Q000502:physiology*; D003056:Cochlear Nerve / Q000473:pathology; D004525:Efferent Pathways; D018072:Hair Cells, Auditory, Outer / Q000473:pathology; D007612:Kanamycin / Q000633:toxicity*; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D000975:Antioxidants; D007612:Kanamycin; D002392:Catechin