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Accueil du site > Equipes de recherche > Equipe CMO (N.Ravel, N.Buonviso) > Annuaire > Pages personnelles > Karyn JULLIARD


par Philippe Litaudon - 30 avril 2014


  • Julliard A-K, Al Koborssy D, Fadool DA, Palouzier-Paulignan B. Nutrient Sensing: Another Chemosensitivity of the Olfactory System. Frontiers in Physiology. 8:468.
    Résumé : Olfaction is a major sensory modality involved in real time perception of the chemical composition of the external environment. Olfaction favors anticipation and rapid adaptation of behavioral responses necessary for animal survival. Furthermore, recent studies have demonstrated that there is a direct action of metabolic peptides on the olfactory network. Orexigenic peptides such as ghrelin and orexin increase olfactory sensitivity, which in turn, is decreased by anorexigenic hormones such as insulin and leptin. In addition to peptides, nutrients can play a key role on neuronal activity. Very little is known about nutrient sensing in olfactory areas. Nutrients, such as carbohydrates, amino acids, and lipids, could play a key role in modulating olfactory sensitivity to adjust feeding behavior according to metabolic need. Here we summarize recent findings on nutrient-sensing neurons in olfactory areas and delineate the limits of our knowledge on this topic. The present review opens new lines of investigations on the relationship between olfaction and food intake, which could contribute to determining the etiology of metabolic disorders.
    Mots-clés : food intake, nutrient sensing, obesity, olfaction, piriform cortex, receptor, transporter, type 2 diabetes.


  • Tong J, Mannea E, Aimé P, et al. Ghrelin enhances olfactory sensitivity and exploratory sniffing in rodents and humans. The Journal of neuroscience: the official journal of the Society for Neuroscience. 31(15):5841-5846.
    Résumé : Olfaction is an integral part of feeding providing predictive cues that anticipate ingestion. Although olfactory function is modulated by factors such as prolonged fasting, the underlying neural mechanisms remain poorly understood. We recently identified ghrelin receptors in olfactory circuits in the brain. We therefore investigated the role of the appetite-stimulating hormone ghrelin in olfactory processing in rodents and humans, testing the hypothesis that ghrelin lowers olfactory detection thresholds and enhances exploratory sniffing, both being related to food seeking. In rats, intracerebroventricular ghrelin decreased odor detection thresholds and increased sniffing frequency. In humans, systemic ghrelin infusions significantly enhanced sniff magnitudes in response to both food and nonfood odorants and air in comparison to control saline infusions but did not affect the pleasantness ratings of odors. This is consistent with a specific effect on odor detection and not the hedonic value of odors. Collectively, our findings indicate that ghrelin stimulates exploratory sniffing and increases olfactory sensitivity, presumably enhancing the ability to locate, identify, and select foods. This novel role is consistent with ghrelin's overall function as a signal amplifier at the molecular interface between environmental and nutritional cues and neuroendocrine circuits controlling energy homeostasis.
    Mots-clés : Adolescent, Adult, Animals, Avoidance Learning, Biotinylation, Exploratory Behavior, Female, Food, Ghrelin, Humans, Lac Operon, Male, Mice, Mice, Knockout, Middle Aged, Rats, Rats, Long-Evans, Receptors, Ghrelin, Smell, Young Adult.