Plasticity in the olfactory system: modulation by the odorant environment and diet

As the primary neuronal element in the olfactory system, olfactory sensory neurons (OSNs) are responsible for detecting odor molecules, transforming chemical information to electrical signals and sending these signals to the brain. Being exposed to the environment, their lifetime is limited. The olfactory epithelium has the remarkable ability to regenerate sensory neurons throughout life. There is little data showing the effects of the environment, such as odorant exposure, on the properties of OSNs. Similarly, knowledge on the modulation by the physiological state of the animal (i.e. nutritional status) is limited. The long-term goal of our group is to investigate how the OSNs function during development, regeneration and under the influence of the environment, using mouse lines in which specific odorant receptors are genetically-tagged. First, we observed that odorant enrichment modulates specifically a population sensitive to the odorant used. Second, we observed that prediabetic state induces a strong deficit in olfactory behavior in mice. This deficit is partly due to a reduction of sensitivity in OSNs. Our results show that olfaction can adapt and evolve throughout life depending on the environment and the physiological state of the animal. This adaptation takes place already at the first level of the olfactory system