K. Yamada et al., REDUCTION IN THE NUMBER OF NADPH-DIAPHORASE-POSITIVE CELLS IN THE CEREBRAL-CORTEX AND STRIATUM IN AGED RATS, Neuroscience research, 24(4), 1996, pp. 393-402
Nitric oxide (NO) plays an important role as a diffusible messenger in
learning and memory. To determine whether changes in NO production in
the brain may be involved in aging-associated brain dysfunction, we m
easured the performance of aged rats in a radial arm maze task, and ca
rried out histochemical examination of the changes in NADPH diaphorase
(NADPH-d)-containing neurons in the brains of aged rats. The performa
nce of aged rats (30 months old) in a radial arm maze task was signifi
cantly impaired compared to the performance of young rats (3 months ol
d). The number of neurons containing NADPH-d reactivity in the cerebra
l cortex and striatum of aged rats was significantly reduced, by appro
ximately 50 and 30%, respectively, compared to that in young rats. NO
synthase activity in discrete brain regions of aged rats, i.e., in the
cerebral cortex, striatum and hippocampus was not different from that
in young rats, although the activity in the cerebellum of aged rats w
as significantly lower than that in young rats. These results suggest
that the reduction in the number of NADPH-d-positive cells in the brai
ns of aged rats may be involved in aging-associated learning impairmen
t in rats.