Arginine and NADPH diaphorase in the rat ventroposterior thalamic nucleus

Simultaneous immunocytochemical staining for arginine (Arg) and histochemical staining for reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd, a marker for nitric oxide synthase) reveals that neuropil in the ventroposterior nucleus of the thalamus is enriched with both Arg-positive glial profiles and NADPHd-positive fibers. NADPHd-positive fibers are often apposed to Arg-positive astrocytes and oligodendrocytes. NADPHd-positive endothelial cells are often adjacent to Arg-positive astrocytes. The results suggest that Arg may be stored in supporting cells, whence it could be supplied to nearby nerve fibers or endothelial cells as substrate for nitric oxide synthase.