NADPH-diaphorase localization in the olfactory system.

NADPH-diaphorase staining was studied in the intact olfactory system and following transections of the olfactory nerve. Intense staining was found in the olfactory epithelia of rat and salamander, especially at the mucosal surface. The olfactory bulb nerve and glomerular layers were also stained. Transection of the olfactory nerve in salamander, or bulbectomy in rat, resulted in decreased staining at the mucosal surface, although staining increased in cells deeper in the epithelium. Deafferentation also caused the disappearance of staining in the olfactory nerve and glomerular layers of the bulb. These results support the notion of a role for NADPH in the olfactory system, perhaps as a biosynthesis substrate for NO modulation of cGMP in the developing epithelium and a complementary role for CO in the adult.