Increased number of NADPH-d-positive neurons within the substantia innominata in Alzheimer's disease.

NADPH-diaphorase histochemistry labels neurons containing nitric oxide synthase, the synthesizing for nitric oxide within the central nervous system. Quantitation revealed a statistically significant increase in the density of intensely (type 1) and moderately (type 2) but not lightly (type 3) NADPH-diaphorase stained neurons within the substantia innominata in AD as compared with age-matched controls. Increased numbers of NADPH-diaphorase neurons suggest excess nitric oxide production which may be neurotoxic to surrounding cholinergic neurons within the substantia innominata in Alzheimer's disease.