Expression of nitric oxide synthase isoforms in cochlea of guinea pig

Objective The distribution of nitric oxide synthase (NOS) isoforms was investigated in the cochlea of the guinea pig by immunohisto-chemistry. Methods The expression of NOS isoforms in the cochlea of the guinea pig was examined with isoform selective anti-NOS antibodies by the avidin-biotin-complex (ABC) procedure. Results Type NOS 1 mainly distributed in the endosteum, the perikaryia of the spiral ganglion cells, the cells of Corti's organ and the spiral ligament in the guinea pig cochlea. Type NOS El mainly distributed in the cochlear nerve, perikaryia of the spiral ganglion cells and the spiral ligament, and also in the cells and the nerve fibre of Corti's organ and in the endothelial lining of cochlear glomeruli. Immunostainning for Type NOS II revealed no immunoreactivity. Conclusion Expression of cNOS isoforms ( Type NOS 1 and Type NOS III) in cochlea are detected. It suggests that NOS involves in the cochlear physiology including the synaptic neurotransmition in cochlea, the regulation of microcirculation and the bone metabolism in the cochlea.