Localization of NADPH-diaphorase/nitric oxide synthase activity in the rat cerebellar cortex: a light and electron microscopical study.

The activity of reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) was examined histochemically in the rat cerebellar cortex at the light and electron microscopical level. Different staining patterns were observed depending on the technique used. Electron dense reaction product was seen on distinct membrane portions of the endoplasmic reticulum including the nuclear envelope in most of the neurons and in endothelial cells. Electron microscopically no activity staining was seen in glial cells, including Bergmann cells. The addition of the detergent Triton X-100, usually applied in the light microscopical diaphorase histochemistry, led to a striking diminution in membrane staining. In such preparations inspected electron microscopically formazan formed small granules which were evenly distributed over the cytoplasm.