Does intranasal application of zinc sulfate produce anosmia in the rat?

Transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) from olfactory sensory neurons to the olfactory bulb as well as odor detection and discrimination were examined in rats in which each nasal epithelium had been irrigated with 0.1-0.5 ml 5% zinc sulfate. After treatment, rats showed few or no deficits in discriminating among odors and in detecting high (1%-0.01%) concentrations of ethyl acetate, but some had deficits in detecting lower concentrations of the odor. In most cases, HRP reaction product filled more than 30% of olfactory bulb glomeruli 2-4 days after treatment with ZnSO4. The behavioral outcomes are in agreement with recent reports of considerable savings in olfaction even after severe reduction of afferent projections to the olfactory bulb. We conclude that, in the rat, intranasal application of ZnSO4, as generally practiced, does not produce anosmia.