The metabolic status and olfactory function

International audience ; Olfaction is an important part of various vital activities, from the detection and processing of environmental odors related to feeding to social behavior and reproduction. Particularly, animals strongly rely on olfaction to locate, choose, consume, and stop to eat food. Thus, the olfactory system does contribute to adjustments in food intake regulation according to the physiological needs, leading to the concept of a multilayered modulation acting from the periphery to higher brain centers. Indeed, both the olfactory mucosa and bulb are under the direct influence of metabolic hormones, peptides, and nutrients, which modulate odor processing according to the internal energetic status at short- and long-term. In mammals, an increasing number of food intake–related factors that modulate neuronal activity have been identified in the past twodecades, reinforcing their putative roles as circulating factors acting at the molecular interface between environmental and nutritional cues. Indeed, pioneer works have shown that these factors could modulate olfactory sensitivity, acting directly or indirectly on neuronal activity. Examination of more integrated physiological conditions, e.g., metabolic state or hunger, has confirmed the tight and complex link between olfaction and endocrine systems, pointing out long-term modulatory effects in cell dynamics and tissue homeostasis related to nutritional imbalances in adulthood. Recently, the maternal metabolic status has even been shown to influence olfactory capabilities and associated behaviors—such as food intake—in offspring. This suggests a programming effect of the maternal nutritional context that could participate to the vicious circle of food intake deregulation, giving rise to a renewed interest of this topic.