Zonal ablation of the olfactory sensory neuroepithelium of the mouse: effects on odorant detection.

Olfactory sensory neurons that express a specific odorant receptor, out of a thousand different, are unevenly distributed within, but restricted to one of four zones of the neuroepithelial sheet in the nasal cavity in the mouse. This zonal restriction of neurons expressing the same odorant receptor may have consequences, e.g. in case of localized injury. We found that the chemical dichlobenil can produce specific and permanent ablation of neurons in odorant receptor expression zone 1, while a higher dichlobenil dose causes reversible toxicity in neighboring zones. In behavior tests, mice lacking part of the olfactory epithelium had an increased detection threshold concentration of two-four orders of magnitude for some odorants but not others, resembling the phenomenon of specific hyposmia. This indicates that the broad tuning properties of single odorant receptors and their large number cannot fully compensate for loss of the receptor(s) with the highest sensitivity for a particular odorant.