Identification of three phospholipase C isotypes expressed in rat olfactory epithelium.

The expression of three phosphoinositide-specific phospholipase C (PLC) isotypes in rat olfactory epithelium was investigated using monoclonal antibodies. In intact animals, PLC beta 1 was not expressed in the olfactory epithelium but was found in glands below the epithelium. However, following unilateral olfactory bulbectomy (OBX), PLC beta 1 was expressed in the dentrites of some olfactory receptor neurons, primarily in the endoturbinates on the unoperated side. PLC gamma 1 immunoreactivity was found in the apices of sustentacular cells and in glands below the epithelium. PLC delta 1 immunoreactivity was found in the glands and in the perinuclear region and dendrites of some receptor neurons. Since none of the PLC isotypes studied were expressed in the cilia of receptor neurons, the results suggest that another PLC isotype is likely to be involved in mediating olfactory transduction.