Nerve growth factor (NGF) and its receptor in rat olfactory epithelium.

Nerve Growth Factor (NGF) is a bioactive protein that plays an important role in the genesis, differentiation, growth, maintenance and aging of the central and peripheral nervous systems. The purpose of this study was to explore the significance of NGF in the turnover, regeneration and maintenance of the olfactory epithelium. We tried to detect NGF and NGF-receptor in the olfactory epithelium of young and mature rats with an immunohistochemical technique. Immunoreactivity to NGF and NGF-receptor was detected in all specimens of olfactory epithelium. Immunoreactivity to NGF was positive in the olfactory nerve cells, especially in the cytoplasm and dendrites, in the basal cell layer, and on fibers piercing the olfactory epithelium. Immunoreactivity to NGF-receptor was positive in the basal cell layer and on fibers piercing the olfactory epithelium. These results suggest that NGF plays a role in the maintenance of olfactory nerve cells, and in the differentiation from the basal cell to the mature olfactory nerve cell, in both the young and the mature rat. In addition, the differences in the density of immunoreactive cells between different parts of the olfactory epithelium support the concept of an active and a quiescent zone in olfactory epithelium turnover.