Odor stimulation causes disappearance of R4B12 epitope on axonal surface molecule of olfactory sensory neurons

Monoclonal antibodies R4B12 and R1D1 label the same subsets of rabbit primary olfactory axons. In the present study, we characterized the R4B12 antigens using immunohistochemical, immunoelectron-microscopic, and biochemical techniques. The R4B12 antigens are expressed on the surface membrane of a subset of primary olfactory axons. Western blot analysis revealed the existence of two forms (115,000 and 90,000 mol.wt) of the R4B12 antigens with different membrane-anchoring structures. Of the two forms, the smaller antigen (90,000 mol. wt) is anchored to the plasma membrane via a phosphatidylinositol linkage and expressed exclusively by the olfactory system. When the rabbit olfactory epithelium was stimulated by odors for 2-8 h in situ, the R4B12 immunoreactivity disappeared from the primary olfactory axons in the glomeruli of the olfactory bulb. These results suggest that the cell surface antigens R4B12 expressed by subsets of primary olfactory axons undergo stimulus-dependent changes by odor stimulation and may be involved in plasticity of olfactory sensory neurons.