Immunohistochemical study on the expression of calcium binding proteins (calbindin-D28k, calretinin, and parvalbumin) in the cerebellum of the nNOS knock-out(-/-) mice.

Nitric Oxide (NO) actively participates in the regulation of neuronal intracellular Ca(2+) levels by modulating the activity of various channels and receptors. To test the possibility that modulation of Ca(2+) buffer protein expression level by NO participates in this regulatory effect, we examined expression of calbindin-D28k, calretinin, and parvalbumin in the cerebellum of neuronal NO synthase knock-out (nNOS((-/-))) mice using immunohistochemistry. We observed that in the cerebellar cortex of the nNOS((-/-)) mice, expression of calbindin-D28k and parvalbumin were significantly increased while expression of calretinin was significantly decreased. These results suggest another mechanism by which NO can participate in the regulation of Ca(2+) homeostasis.