title: Orexin A effects on the olfactory bulb spontaneous activity and odor responsiveness in freely breathing rats.
abstract: The mitral cells (MCs) of the olfactory bulb (OB) are relay neurons between the periphery and the central nervous structures. MCs receive in turn a centrifugal control from several higher brain centers that depends on the nutritional state. In this study, we investigated the effects of orexin A (ORX), a novel molecule known to regulate food intake and whose receptors are present in the OB, on the electrophysiological activity of single MCs. Using icv-injections and direct applications on the OB, we determined the respective central and local effects of this molecule on the MCs' spontaneous firing activity and responsiveness to different odors. Icv-injections and local OB-applications were found to induce a significant decrease in spontaneous firing activity in 14% and 50% of the recorded MCs, respectively. In one case, ORX application on the OB caused a significant firing increase. Effects of OB-applications had shorter delays. The responsiveness of some MCs to food and non-food odors was also changed, but the proportion of changes was not statistically significant. Icv-injection effects likely resulted from a local action of ORX on the OB. Changes of spontaneous firing activity and odor responsiveness are discussed in terms of regulation of the functioning of the olfactory system.
authors.affiliation: CNRS UMR5020 Neurosciences and Systèmes Sensoriels, Université Claude Bernard Lyon 1, 50 avenue Tony Garnier, 69366 LYON Cedex 07, France. aapelbaum@olfac.univ-lyon1.fr
authors.forename: A F
authors.initials: AF
authors.lastname: Apelbaum
authors.forename: A
authors.initials: A
authors.lastname: Perrut
authors.forename: M
authors.initials: M
authors.lastname: Chaput
mesh_terms: D000818:Animals; D007267:Injections; D047908:Intracellular Signaling Peptides and Proteins / Q000008:administration & dosage*; D008297:Male; D009479:Neuropeptides / Q000008:administration & dosage*; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology*; D000068797:Orexins; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration / Q000187:drug effects; D012903:Smell / Q000187:drug effects* / Q000502:physiology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins