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RESEARCH PRODUCT

Short-term impact of a Western diet on the physiology of the peripheral olfactory system

subject

description

Current feeding behaviors contribute to the epidemic levels of obesity and diabetes observed in Europe and worldwide. Both the quantity and the quality of ingested food are incriminated. Together with other sensory modalities, olfaction is involved in the control of food intake. Olfactory cues can influence eating behaviors, yet the nutritional status and diet can also alter olfactory abilities. Patients with metabolic disorders present impaired olfactory sensitivity which could in turn worsen their eating behaviors.Here we examined the short-term impact of a Western diet enriched in fat and sugar (High Fat High Sugar, HFHS) on the anatomy and physiology of the olfactory epithelium of postnatal mice. We used a transgenic line of mice expressing GFP under the promoter of the SR1 odorant receptor in order to monitor the properties of a define population of neurons. After 8 weeks of diet, HFHS fed animals were glucose intolerant without any change in basal glycaemia and insulinemia and presented higher adiposity but no overweight compared to control mice. We measured electro-olfactogram amplitudes in response to two ligands of the SR1 olfactory receptor: amyl acetate and (R)-(+)-carvone. Detection thresholds of amyl acetate estimated from the dose-response curves were higher after 8 weeks of a HFHS diet (medians were 10-5 M for control vs 10-3 M for HFHS, p < 0.01). Reconstruction of the cilia of SR1 olfactory sensory neurons revealed shorter cilia in HFHS mice compared to control animals (4.5 ± 0.3 m vs 6.0 ± 0.3 m, p < 0.01).Our results demonstrate that diet enriched in fat and sucrose can alter the physiology of the olfactory epithelium on a short term. Anatomical changes of individual olfactory sensory neurons may participate to the reduced olfactory sensitivity. Olfactory dysfunctions appear early on after exposure to a Western diet.