title: Top-down inputs from the olfactory cortex in the postprandial period promote elimination of granule cells in the olfactory bulb.
abstract: Elimination of granule cells (GCs) in the olfactory bulb (OB) is not a continual event but is promoted during a short time window in the postprandial period, typically with postprandial sleep. However, the neuronal mechanisms for the enhanced GC elimination during the postprandial period are not understood. Here, we addressed the question of whether top-down inputs of centrifugal axons from the olfactory cortex (OC) during the postprandial period are involved in the enhanced GC elimination in the OB. Electrical stimulation of centrifugal axons from the OC of anesthetized mice increased GC apoptosis. Furthermore, pharmacological suppression of top-down inputs from the OC to the OB during the postprandial period of freely behaving mice by γ-aminobutyric acid (GABA)A receptor agonist injection in the OC significantly decreased GC apoptosis. Remarkable apoptotic GC elimination in the sensory-deprived OB was also suppressed by pharmacological blockade of top-down inputs. These results indicate that top-down inputs from the OC to the OB during the postprandial period are the crucial signal promoting GC elimination, and suggest that the life and death decision of GCs in the OB is determined by the interplay between bottom-up sensory inputs from the external world and top-down inputs from the OC.
authors.affiliation: Department of Physiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan; CREST, Japan Science and Technology Agency, Saitama, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Komano-Inoue
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Manabe
authors.forename: Mizuho
authors.initials: M
authors.lastname: Ota
authors.forename: Ikue
authors.initials: I
authors.lastname: Kusumoto-Yoshida
authors.forename: Takeshi K
authors.initials: TK
authors.lastname: Yokoyama
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mori
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001369:Axons / Q000187:drug effects / Q000502:physiology; D002408:Catheters, Indwelling; D002452:Cell Count; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D008810:Mice, Inbred C57BL; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D066194:Olfactory Cortex / Q000187:drug effects / Q000502:physiology*; D009833:Olfactory Pathways / Q000187:drug effects / Q000502:physiology; D019518:Postprandial Period / Q000187:drug effects / Q000502:physiology*; D011963:Receptors, GABA-A / Q000378:metabolism; D012683:Sensory Deprivation / Q000502:physiology
chemical_list: D058785:GABA-A Receptor Agonists; D011963:Receptors, GABA-A; D009118:Muscimol
keywords: adult neurogenesis; apoptosis; mice; olfactory bulb; olfactory cortex; top-down inputs