Transregulation of erbB expression in the mouse olfactory bulb

Previously, we have shown that erbB-3 expression is restricted to the enshe athing cells of the olfactory nerve layer, while erbB-4 is found in the per iglomerular and mitral/tufted cells of the olfactory bulb and in cells comi ng out from the rostral migratory stream of the subependymal layer. In the present work, we have treated adult mice with zinc sulfate intranasal irrig ation and analyzed erbB-3 and erbB-4 expression in the deafferented olfacto ry bulb. Following treatment, olfactory axons undergo degeneration, as indi cated by the loss of OMP expression in the deafferented olfactory bulb. The thickness of the olfactory nerve layer is reduced, but the specific intens ity of erbB-3 labeling in the remaining olfactory nerve layer is increased with respect to control. Interestingly, following deafferentation, erbB-4 i mmunoreactivity decreases specifically in cell types that normally make syn aptic contacts with primary olfactory neurons in the glomeruli, i.e. perigl omerular and mitral/tufted cells. Partial lesion of the olfactory epitheliu m allows regenerative axon growth of olfactory neurons to the olfactory bul b. Following olfactory axon regeneration, erbB-3 and erbB-4 immunoreactivit y in the olfactory bulb is similar to control. Thus, like tyrosine hydroxyl ase, the down regulation of erbB-4 expression in the periglomerular cells i s reversible.