RESUMO
BACKGROUND AND OBJECTIVES: Nitric oxide (NO) is an inorganic, gaseous free radical that carries a variety of messages between cells. The histochemical demonstration of neuronal betaNADPH-d is the demonstration of the presence of NOS. The purpose of this study was to identify the existence of NOS and the difference of the expression of betaNADPH-d in mouse and gerbil cochleae. MATERIALS AND METHODS: Each of the eight cochleae of Mongolian gerbil (Meriones unguiculatus) and mice (CJU/A) were fixed by cardiac perfusion with 4% paraformaldehyde in 0.1M phosphate buffer solution. The en-bloc cochleae were incubated after decalcification, and stained with betaNADPH-d and counterstained with acid fuchsin. The relative intensity of staining was decided in the same location of cochlea. RESULTS: Most supporting cells were strongly stained except Claudius cells and Boettcher's cells in gerbil. However, Boettcher's cells were strongly stained in mice. Outer hair cells, inner hair cells, basial membrane and lining cells of spiral limbus were strongly stained. Interdental cells of spiral limbus, inner border cells and intermediate cells of stria vascularis were moderately stained. Tectorial membrane and amorphous layer of basial membrane were not stained. CONCLUSION: Using betaNADPH-d staining, this study documents the presence of nitric oxide synthase in mice and gerbil cochleae and the difference of staining between two species.