Evidence for different chemosensory signal transduction pathways in olfactory and vomeronasal neurons.

Both the olfactory and vomeronasal epithelia mediate chemosensory reception. Here we report that several molecules that are highly expressed in the olfactory epithelium and therefore are likely to be important mediators of olfactory signal transduction (Golfalpha, adenylyl cyclase III and the olfactory cyclic nucleotide gated ion channel) are not present in the vomeronasal epithelium. Therefore it appears that distinct molecules mediate chemosensory signal transduction in the olfactory and vomeronasal epithelia. The genes for Golfalpha, adenylyl cyclase III, the olfactory cyclic nucleotide gated ion channel, Ggamma8 and olfactory marker protein which are all expressed in the olfactory epithelium have consensus Olf-1 binding sites. The transcription factor Olf-1 was found to be highly expressed in the olfactory epithelium and was detected at a similar level in the vomeronasal epithelium. The expression pattern of Olf-1 did not correlate with that of molecules involved in olfactory signaling but was more similar to the expression pattern of Ggamma8 and olfactory marker protein which are found both in olfactory and vomeronasal neurons. Therefore, expression of Olf-1 in the olfactory epithelium and the presence of Olf-1 binding sites in a number of different genes found to be expressed in the olfactory epithelium are not sufficient to explain the observed gene expression patterns.