Expression of Nitric Oxide Synthase in the Olfactory Bulb of the Rat during Development

Park, Yong Jin; Lee, Mun Yong; Yoon, He Ro; Joung, Il Song; Shin, Soon Lim; Chun, Myung Hoon

Abstract

BACKGROUND AND OBJECTIVES: The presence and distribution of NADPH-diaphorase activity in the olfactory bulb during development has been reported. But the precise localization of NO-synthase (NOS) in the olfactory bulb during the developmental stages has not been studied yet. Therefore, we investigated the localization of NOS-immunoreactivity in a developing rat olfactory bulb by immunohistochemistry.
MATERIALS AND METHODS
A total of 32 male and female Sprague-Dawley rats. They were of several prenatal and postnatal stages, such as the following: embryonic day 16 (E16), E18, E20, postnatal day 1 (P1), P5, P7, P14 and adult. Indirect immunoperoxidase method using rabbit polyclonal anti-bNOS antibody was performed for detecting the NOS immunoreactivity.
RESULTS
In the main olfactory bulb, the first NOS-immunoreactive (IR) neurons were observed in the presumptive granule cell layer (GCL) by E18, and in the glomerular layer (GL) by P1. The density of these neurons was increased as the development stage approached the adult stage. In the GCL, two types of NOS-immunoreactive neurons were observed: intensively stained large, short axon cells and weakly stained small, granule cells. The first, localized in the deeper part of the GCL, was observed in the earlier developmental stages, and the latter which increased in number to the adult period was observed by P1. In the accessory olfactory bulb, NOS-IR neurons were first detected in the GCL by P1, and increased in number to the adult period. The pattern of NOS-IR neurons in the GCL of the accessory olfactory bulb is similar to that in the main olfactory bulb.
CONCLUSION
Our results demonstrated that bNOS had a characteristic temporal and spatial patterns of expression in the main and accessory olfactory bulb of the rat during development.