Contribution of individual olfactory receptors to odor-induced attractive or aversive behavior in mice

Odorants are recognized by multiple olfactory receptors (ORs) and induce innate behaviors like attraction or aversion via olfactory system in mice. However, a role of an individual OR is unclear. Muscone is recognized by a few ORs including MOR215–1 and MOR214–3, and attracts male mice. Odor preference tests using MOR215–1 knockout mice revealed that MOR215–1 and other OR(s), possibly including MOR214–3, are involved in the attraction. (Z)-5-tetradecen-1-ol (Z5–14:OH) activates ~3 ORs, including Olfr288, and evokes attraction at low levels but aversion at higher levels. Olfr288 knockout mice show no attraction but aversion, suggesting Olfr288 is involved in preference for Z5–14:OH, whereas activation of other low-affinity Z5–14:OH receptors evokes aversion. Each OR appears to send a signal to a neural circuit that possesses distinct valence, leading to a certain behavior. The final output behavior with multiple ORs stimulation is determined by summation (addition or competition) of valences coded by activated ORs.