title: Possible role of calcitonin gene-related peptide in trigeminal modulation of glomerular microcircuits of the rodent olfactory bulb.
abstract: Chemosensation in the mammalian nose comprises detection of odorants, irritants and pheromones. While the traditional view assigned one distinct sub-system to each stimulus type, recent research has produced a more complex picture. Odorants are not only detected by olfactory sensory neurons but also by the trigeminal system. Irritants, in turn, may have a distinct odor, and some pheromones are detected by the olfactory epithelium. Moreover, it is well established that irritants change odor perception and vice versa. A wealth of psychophysical evidence on olfactory-trigeminal interactions in humans contrasts with a paucity of structural insight. In particular, it is unclear whether the two systems communicate just by sharing stimuli, or whether neuronal connections mediate cross-modal signaling. One connection could exist in the olfactory bulb that performs the primary processing of olfactory signals and receives trigeminal innervation. In the present study, neuroanatomical tracing of the mouse ethmoid system illustrates how peptidergic fibers enter the glomerular layer of the olfactory bulb, where local microcircuits process and filter the afferent signal. Biochemical assays reveal release of calcitonin gene-related peptide from olfactory bulb slices and attenuation of cAMP signaling by the neuropeptide. In the non-stimulated tissue, the neuropeptide specifically inhibited the basal activity of calbindin-expressing periglomerular interneurons, but did not affect the basal activity of neurons expressing calretinin, parvalbumin, or tyrosine hydroxylase, nor the activity of astrocytes. This study represents a first step towards understanding trigeminal neuromodulation of olfactory-bulb microcircuits and provides a working hypothesis for trigeminal inhibition of olfactory signal processing. This article is protected by copyright. All rights reserved.
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Federica
authors.initials: F
authors.lastname: Genovese
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Hanke Gwendolyn
authors.initials: HG
authors.lastname: Bauersachs
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Gräßer
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Kupke
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Laila
authors.initials: L
authors.lastname: Magin
authors.affiliation: Interfacultary Biomedical Faculty, Heidelberg University, Heidelberg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Daiber
authors.affiliation: Institute of Physiology and Pathophysiology, University of Erlangen-Nuernberg, Erlangen, Germany.
authors.forename: Julika
authors.initials: J
authors.lastname: Nakajima
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Möhrlen
authors.affiliation: Institute of Physiology and Pathophysiology, University of Erlangen-Nuernberg, Erlangen, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Messlinger
authors.affiliation: Department of Animal Molecular Physiology, Centre of Organismal Studies, Heidelberg University, Heidelberg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Frings
keywords: Interneuron; Neuropeptide; Olfaction; calbindin