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Plasticité morphologique des astrocytes glomérulaires du bulbe olfactif chez le rat : rôle dans la relation entre l'olfaction et la prise alimentaire

Abstract : Olfaction plays a key role in the elaboration of the hedonic value of foods and the regulation of food intake. Reciprocally, the detection of food odors is influenced by the metabolic state. Fasting increases olfactory performances, notably by increasing neuronal activity in the olfactory bulb (OB). Within the OB glomeruli, the glutamatergic synapses between olfactory sensory neurons and mitral cells are regulated by astrocytes, periglomerular neurons and centrifugal afferents. Astrocytes, which support mecanisms of metaplasticity in the brain, may drive the metabolic regulation of the olfactory response in the OB. To test whether OB glomerular astrocytes are involved in the metabolic sensing of the olfactory system, we compared the astroglial processes expansion by quantification of the GFAPlabelled area in fed and fasted rats.Astroglial spreading was markedly increased in fasting rats, as compared to fed rats, in all regions of the OB after 17h-fasting. Intra-peritoneal administration of the anorexigenic peptide PYY3-36 or glucose in 17h-fasted rats respectively decreased their food intake or restored their glycemia and both reversed the increased astroglial deployment induced by fasting. Direct application of orexigenic peptides ghrelin and NPY on OB acute slices, resulted in an increase of the astroglial deployment, whereas application of PYY3-36 oppositely resulted in astroglial retraction within the glomeruli. These results are in close agreement with the effects of fasting or satiation on the morphology of astrocytes.The deployment of the glomerular astroglial processes clearly varies according to the metabolic state of the rats, and is influenced by food intake regulatory peptides. This plasticity may participate in the adaptation of the olfactory sensitivity to food intake.
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https://tel.archives-ouvertes.fr/tel-01800054
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Submitted on : Friday, May 25, 2018 - 2:55:05 PM
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Virginie Daumas-Meyer. Plasticité morphologique des astrocytes glomérulaires du bulbe olfactif chez le rat : rôle dans la relation entre l'olfaction et la prise alimentaire. Alimentation et Nutrition. Université Paris Saclay (COmUE), 2017. Français. ⟨NNT : 2017SACLA019⟩. ⟨tel-01800054⟩

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