title: Role of vasoactive intestinal peptide in seasonal encoding by the suprachiasmatic nucleus clock.
abstract: The neuropeptide vasoactive intestinal peptide (VIP) is critical for the proper functioning of the neural circuit that generates circadian rhythms. Mice lacking VIP show profound deficits in the ability to generate many behavioral and physiological rhythms. To explore how the loss of VIP impacts on the intact circadian system, we carried out in vivo multiunit neural activity (MUA) recordings from the suprachiasmatic nucleus of freely moving VIP knockout (KO) mice. The MUA rhythms were largely unaltered in the VIP KO mice, with no significant differences being seen in the amplitude or phase of the rhythms in light-dark conditions. Robust differences between the genotypes were revealed when the mice were transferred from light-dark to constant darkness conditions. In addition, the ability of the VIP KO mice to encode changes in photoperiod was examined. Strikingly, the behavioral and physiological rhythms of VIP KO mice showed no adaptation to short or long photoperiods. The data indicate that the intact circadian system can compensate for some of the consequences of the loss of VIP, whereas this peptide is indispensable for endogenous encoding of seasonal information.
authors.affiliation: Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
authors.forename: Eliane A
authors.initials: EA
authors.lastname: Lucassen
authors.forename: Hester C
authors.initials: HC
authors.lastname: van Diepen
authors.forename: Thijs
authors.initials: T
authors.lastname: Houben
authors.forename: Stephan
authors.initials: S
authors.lastname: Michel
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Colwell
authors.forename: Johanna H
authors.initials: JH
authors.lastname: Meijer
mesh_terms: D000200:Action Potentials / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology*; D004567:Electrodes, Implanted; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009043:Motor Activity / Q000235:genetics; D017440:Photoperiod; D018709:Statistics, Nonparametric; D013493:Suprachiasmatic Nucleus / Q000502:physiology*; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000172:deficiency; D014851:Wakefulness / Q000235:genetics / Q000502:physiology
chemical_list: D014660:Vasoactive Intestinal Peptide