RT Journal Article SR Electronic T1 Enzymatic Conversion of Odorants in Nasal Mucus Affects Olfactory Glomerular Activation Patterns and Odor Perception JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 16391 OP 16398 DO 10.1523/JNEUROSCI.2527-10.2010 VO 30 IS 48 A1 Ayumi Nagashima A1 Kazushige Touhara YR 2010 UL http://www.jneurosci.org/content/30/48/16391.abstract AB Odor information is decoded by a combination of odorant receptors, and thus transformed into discrete spatial patterns of olfactory glomerular activity. It has been found, however, that for some odorants, there are differences between the ligand specificity of an odorant receptor in vitro and its corresponding glomerulus in vivo. These observations led us to hypothesize that there exist prereceptor events that affect the local concentration of a given odorant in the nasal mucus, thus causing the apparent specificity differences. Here we show that odorants with functional groups such as aldehydes and esters are targets of metabolic enzymes secreted in the mouse mucus, resulting in their conversion to the corresponding acids and alcohols. The glomerular activation patterns elicited by an enzyme-targeted odorant in the olfactory bulb was different in the presence of an enzyme inhibitor in the mucosa, suggesting that the enzymatic conversion occurs fast enough to affect recognition of the odorant at the levels of olfactory sensory neurons. Importantly, olfactory discrimination tests revealed that mice behaviorally trained to associate an enzyme-targeted odorant to sugar rewards could not discriminate the odorant after treatment with the enzyme inhibitor. These results reveal that the enzymatic conversion of odorants in the nasal mucus appears be fast enough to affect olfactory perception, which sheds light on the previously unappreciated role of nasal mucosal enzymes in odor sensation.