Changes in nitric oxide synthase activities in the cerebellum during development and aging of C57BL/6 mice

Nitric oxide (NO) is one of the neurotransmitters in the cerebellum. Activities of NO synthase and densities of granule cells were determined in the cerebellum in an attempt to elucidate a mechanism of biochemical changes on the anatomical basis during aging. Activities of Ca2+/calmoduline dependent NO synthase were measured in the cerebellum in male and female mice, from 18 gestation days to 28 months of age. There were significant differences in NO synthase activities among the groups of prenatal (18 gestation days), middle aged (5-18 months) and old aged (21-28 months) mice. Between groups of old and middle ages, a significant decrease with aging was found in the mean density of granular cells, which express NO synthase. Changes in NO synthase activities and granule cell densities occurred to a similar degree between old and middle ages. The present data suggest that an age-associated rise and fall of its activities likely occur in parallel with those of granule cell densities, and thus may represent impairment of cerebellar function during aging.