The signal-transduction pathways of the peripheral olfactory organ and their impairment in vertebrates

Animals rely on olfaction to detect and process invaluable chemical information about their environment. For olfaction to function, chemicals must first be detected, which leads to the activation of signal-transduction pathways at the peripheral olfactory organ. As the olfactory system is in direct contact with the environment, the system is constantly vulnerable to damage by contaminants entering the atmosphere or hydrosphere. Contaminants may have a variety of effects, including disrupting olfactory signals generated during chemical detection, or altering numerous targets along the signal transduction pathway. With any impairment of chemical detection, animals may be unable to rely on olfaction to make correct decisions about their environment and thus their fitness. While other reviews have focussed on olfactory toxicology in general, here we specifically explore how contaminants may affect the signal-transduction pathways at various points and link those changes to olfactory functionality across vertebrates with a focus on fishes.