Physiological and histological recovery of the olfactory mucosa of the frog after a dichlobenil injection.

Four days after a single systemic injection of 50 mg/kg of dichlobenil (2,6-dichlorobenzonitrile), the olfactory neuroepithelium of the frog is extensively damaged. At the same time, electrophysiological responses to odorant stimulations (2-heptanone, D-limonene, amyl acetate, camphor) are largely reduced. Pretreatment of the animals with metyrapone, an inhibitor of cytochrome P-450 enzymatic systems, inhibits the histological and physiological toxic effects of the dichlobenil injection. The olfactory tissue recovered 3 months after the dichlobenil injections and responses to odorant stimulations returned. The same dichlobenil injections did not induce lesions in the vomeronasal neuroepithelium.