Dizocilpine attenuates streptomycin-induced vestibulotoxicity in rats

NMDA receptor mediated excitotoxicity contributes substantially to aminoglycoside antibiotic-induced cochlear damage. Since vestibular as well as cochlear hair cells have glutamatergic synapses, aminoglycoside-induced vestibulotoxicity may also have an excitotoxic component. This hypothesis was tested by examining the effects of the uncompetitive NMDA receptor antagonist dizocilpine on streptomycin-induced vestibulotoxicity. Streptomycin-treated rats exhibited almost complete destruction of sensory hair cells in the crista ampullaris, vestibular impairment in the drop test, and hyperkinesia. Concurrent treatment with dizocilpine not only rescued a substantial population of sensory hair cells in the cristae, but prevented the attendant hyperkinesis and vestibular impairments. These results indicate that excitotoxic mechanisms contribute to aminoglycoside-induced vestibulotoxicity and that NMDA antagonists may be useful in attenuating aminoglycoside ototoxicity.