[Methylcobalamin, antagonist to transient ototoxic action of gentamicin].
OBJECTIVE
To explore whether is methylcobalamin effective in prophylaxis of AmAn ototoxic action.


METHODS
We attempted to use a single injection of gentamicin(125 mg/Kg b.i.w.) to make an animal (guinea pig) model of transient sensory disturbance of hearing, and by a series observation of the changes in ECochG to find out the antagonistic action of methylcobalamin which was simultaneously given to animals(1 mg/Kg, i.m.) followed injection of gentamicin.


RESULTS
1. The transient ototoxic action of gentamicin may cause delay of latency and diminution of amplitude of CAP N1 and N2 in animals with a single injection of gentamicin. Though the interval between N1 and N2 prolonged, the changes were still within normal ranges. 2. By contrast, the changes of delay at N1 and N2 as mentioned above were significantly improved in animals administered simultaneously with methylcobalamin.


CONCLUSIONS
It indicated that in addition to the improvement of physiologic function of nerve fibres, methylcobalamin may be also an agent to prevent the transient ototoxic action of gentamicin. Due to methylcobalamin acts as a methyl donor, it participates the synthesis of SAM (S-adenosylmethionine) and thus products GSH(Glutathion SH), the latter may inhibit ototoxic side-effects of gentamicin.
Jin
X J
XJ
Department of Otorhinolaryngology, Renji Hospital, Second Medical University, Shanghai 200001.
Shen
X R
XR
Jin
X M
XM
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001300:Audiometry, Evoked Response; D003051:Cochlea / Q000187:drug effects*; D003056:Cochlear Nerve / Q000187:drug effects*; D005839:Gentamicins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D006168:Guinea Pigs; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000494:pharmacology*
D005839:Gentamicins; C019476:mecobalamin; D014805:Vitamin B 12