Immunohistochemical demonstration of inducible nitric oxide and nuclear factor-kappa B with reference to age-related changes in the mouse spiral and vestibular ganglion.

The morphology and immunohistochemistry of inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-kappa B) were studied on the spiral and vestibular ganglion of young and old ddy mice. The significant decrease in the number of the spiral ganglion cells and a significant expression of iNOS and NF-kappa B were observed in old mice. In contrast, in the vestibular ganglion of all animals examined, decrease in the number of the ganglion cells or expression of iNOS and NF-kappa B were not observed. Although the relevance of enzymatic systems for the protection of vestibular ganglion cells in old individuals from harmful oxidative stress increased with aging should be further clarified, lack of harmful stress due to nitric oxide (NO) may be one of the plausible reasons for that the vestibular ganglion cells were not decreased in number with aging, since iNOS was not detected in the vestibular ganglion cells in the animals tested in the present study.