NADPH diaphorase is developmentally regulated in rat olfactory epithelium

In vertebrate olfactory receptor neurons, NO synthase (NOS) has been detect ed in embryonic and early postnatal stages. However, expression of the enzy me in the mature epithelium is still controversial. We analyzed the develop mental expression pattern of the histochemical NOS-marker NADPH diaphorase (NADPHd) in the olfactory epithelium of young rats. NADPHd was expressed in a small subset of olfactory receptor neurons as early as P0. Between P0 an d P24 the number of labeled neurons increased 10-fold, stabilizing thereaft er. Whereas NADPHd was generally found in the somata, a transitory dendriti c expression was observed between P2 and P5. This dynamic postnatal regulat ion of the cellular distribution of NADPHd appears to reflect developmental processes within the olfactory epithelium. NeuroReport 12:1039-1043 (C) 20 01 Lippincott Williams & Wilkins.