Ex Vivo Multisite Electro-olfactogram Recordings in Rabbit Neonates

Electro-olfactogram (EOG) recording is a technique that has been used in the field of olfaction for many decades to measure the electrical activity generated by olfactory receptor neurons (ORNs) in response to odor stimuli. In the late 1980s, the development of ex vivo preparation facilitated EOG recordings in mammals. This method provides access to all olfactory turbinates, allowing for recordings lasting several hours. It has greatly contributed to our understanding of olfactory physiology and the functional links between olfaction, various behaviors, and pathologies. Although many innovative techniques are available to study olfaction in the twenty-first century, EOG recordings can still provide valuable insights, particularly when combined with other approaches. For example, the relationship between peripheral olfaction and food intake can be studied, by manipulating orexigenic and anorexigenic agents, or by modifying the animals' diet. Moreover, the connections between olfaction and the intestinal and/or nasal microbiota composition, diabetes, or peripheral plasticity resulting from learning processes can also be examined from a peripheral perspective. The ex vivo multisite EOG recording technique has been recently proved to be particularly useful in newborn rabbits. This technique has demonstrated the high native sensitivity of ORNs to a signal naturally emitted by all rabbit mothers, the mammary pheromone, throughout the olfactory mucosa. Moreover, it has also been observed that ORNs are involved in increased behavioral reactivity due to pheromone-induced odor learning, as well as in differentially processing synthetic and analytical odor mixtures. The ex vivo multisite EOG recording method is expected to remain a useful tool in future research, having in mind that it is both simple and cost-effective to implement.