Olfactory neurons expressing transient receptor potential channel M5 (TRPM5) are involved in sensing semiochemicals

Olfactory sensory neurons (OSNs) in the main olfactory epithelium respond to environmental odorants. Recent studies reveal that these OSNs also respond to semiochemicals such as pheromones and that main olfactory input modulates animal reproduction, but the transduction mechanism for these chemosignals is not fully understood. Previously, we determined that responses to putative pheromones in the main olfactory system were reduced but not eliminated in mice defective for the canonical cAMP transduction pathway, and we suggested, on the basis of pharmacology, an involvement of phospholipase C. In the present study, we find that a downstream signaling component of the phospholipase C pathway, the transient receptor potential channel M5 (TRPM5), is coexpressed with the cyclic nucleotide-gated channel subunit A2 in a subset of mature OSNs. These neurons project axons primarily to the ventral olfactory bulb, where information from urine and other socially relevant signals is processed. We find that these chemosignals activate a subset of glomeruli targeted by TRPM5-expressing OSNs. Our data indicate that TRPM5-expressing OSNs that project axons to glomeruli in the ventral area of the main olfactory bulb are involved in processing of information from semiochemicals.