Expression of Inducible Nitric Oxide Synthase in Cochlea of White and Pigmented Guinea Pigs Exposed to Impulsive Noise

Objective The expression of inducible nitric oxide synthase(iNOS) was investigated in the cochlea of white and pigmented guinea pigs exposed to impulsive noise to explore the contribution of melanin in protecting cochlea from damage.Methods Both white and pigmented guinea pigs were exposed to the impulsive noise to establish the animal model of cochlea injury.The expression of iNOS in the cochlea was examined by the method of immunohistochemistry.Results There showed a positive expression of iNOS in the cochlea of white and pigmented guinea pigs exposed to impulsive noise,and the iNOS expression level in the area of stria vascularis and spiral ganglion was higher.The white guinea pigs had a higher iNOS expression level in the cochlea than the pigmented guinea pigs.Conclusion The mechanism of melanin in counteracting cochlea injury induced by impulsive noise is probably related with the inhibition of iNOS expression in the cochlea.