Nitric oxide synthase inhibitor reduces the apoptotic change in the cisplatin-treated cochlea of guinea pigs

Cisplatin is known to cause inner ear damage. The role of nitric oxide (NO) in the cochlea of the guinea pigs after injections of cisplatin or a combi nation of cisplatin and NO synthase (NOS) inhibitor [N-G-nitro-L-arginine m ethyl ester (L-NAME)] i.p. was examined by means of immunohistochemistry. T hree days after injection, the cochleas were examined immunohistochemically for single-stranded DNA (ssDNA). We found that ssDNA was expressed in the stria vascularis and spiral ganglion cells of the cisplatin-treated cochlea . In the L-NAME/cisplatin-treated cochlea, the number of cells that exhibit ed positive staining for ssDNA was markedly reduced. High NO levels lead to inner ear dysfunction under pathological conditions. Our results indicate that NO mediates the ototoxicity of cisplatin. [(C) 2000 Lippincott William s & Wilkins].