Assessment of Olfactory Toxicity in Rodents

Abstract

AbstractThis chapter focuses on the main olfactory system of rodents that is used to detect small molecules. The olfactory system begins with sensory olfactory neurons found within the olfactory epithelium that lines part of the dorsal or dorsoposterior nasal cavity. These neurons play a critical role in olfaction and current tests of the integrity or function of the olfactory system in rodents often begins with a histologic assessment of this epithelium. Toxicant-induced olfactory epithelial lesions are often site-specific and dependent on the intranasal regional dose of the inhaled chemical and the inherent sensitivity of this epithelial tissue to the chemical of interest. In some cases, additional behavioral assessment of olfactory function may be performed in rodents. These behavioral tests can range from simple efforts to assess an animal’s response to a novel odorant to more complicated tests evaluating olfactory discrimination or olfactory thresholds in exposed animals. These more complicated tests often require specialized equipment and extensive training of the animal to display an odor-mediated behavior. This chapter provides an update of our current understanding of chemically induced olfactory toxicity with a special emphasis on research of interest to neurotoxicologists. Despite advancements made to the study of olfaction in rodents, our knowledge of the olfactory toxicity of many chemicals remains incomplete. This is surprising given the known association between changes in olfactory ability in people following either occupational exposure to chemicals or with a variety of neurodegenerative diseases.Key wordsRodent olfactionNasal pathologyOlfactory discrimination testingOlfactory threshold