Dihydronicotinamide adenine dinucleotide diaphorase in the central nervous system of the crested newt.

By using a histochemical procedure, the distribution of neurons containing dihydronicotinamide adenine dinucleotide diaphorase (NADPHd) was examined in the brain, retina and olfactory epithelium of the urodele amphibian Triturus carnifex. Positive nerve fibers and terminals were observed throughout the brain and cell bodies were seen within the telencephalon, optic tectum, brain stem, cerebellum and spinal cord. In the retina, NADPHd labeling was localized in the outer segment of photoreceptors and in some amacrine cells as well as in the outer and inner plexiform layers. In the olfactory epithelium, NADPHd labeling was found in the olfactory neurons. By comparing NADPHd distribution with nitric oxide synthase (NOS) immunoreactivity (using a polyclonal antiserum raised against mouse cerebellar NOS) it was found that NADPHd labeling and NOS immunoreaction patterns generally matched. The organization of NADPHd and NOS containing neurons in the central nervous system of the crested newt, which is simpler than in other vertebrates investigated, shows some peculiarities, such as the occurrence of NADPHD in the pinealocytes of the epiphysis, nucleus rubber of the brain stem and eminentia cerebellaris ventralis of the cerebellum.