title: Anxiolytic-Like Effects of Increased Ghrelin Receptor Signaling in the Amygdala.
abstract: Besides the well-known effects of ghrelin on adiposity and food intake regulation, the ghrelin system has been shown to regulate aspects of behavior including anxiety and stress. However, the effect of virus-mediated overexpression of the ghrelin receptor in the amygdala has not previously been addressed directly.
  
  
  
  First, we examined the acute effect of peripheral ghrelin administration on anxiety- and depression-like behavior using the open field, elevated plus maze, forced swim, and tail suspension tests. Next, we examined the effect of peripheral ghrelin administration and ghrelin receptor deficiency on stress in a familiar and social environment using the Intellicage system. Importantly, we also used a novel approach to study ghrelin receptor signaling in the brain by overexpressing the ghrelin receptor in the amygdala. We examined the effect of ghrelin receptor overexpression on anxiety-related behavior before and after acute stress and measured the modulation of serotonin receptor expression.
  
  
  
  We found that ghrelin caused an anxiolytic-like effect in both the open field and elevated plus maze tests. Additionally, it attenuated air-puff-induced stress in the social environment, while the opposite was shown in ghrelin receptor deficient mice. Finally, we found that overexpression of the ghrelin receptor in the basolateral division of the amygdala caused an anxiolytic-like effect and decreased the 5HT1a receptor expression.
  
  
  
  Ghrelin administration and overexpression of the ghrelin receptor in the amygdala induces anxiolytic-like behavior. Since the ghrelin receptor has high constitutive activity, ligand-independent signaling in vivo may be important for the observed anxiolytic-like effects. The anxiolytic effects seem to be mediated independently from the HPA axis, potentially engaging the central serotonin system.
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Morten
authors.initials: M
authors.lastname: Jensen
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Cecilia
authors.initials: C
authors.lastname: Ratner
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Olga
authors.initials: O
authors.lastname: Rudenko
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Søren H
authors.initials: SH
authors.lastname: Christiansen
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Skov
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: Cecilie
authors.initials: C
authors.lastname: Hundahl
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye).
authors.forename: David P D
authors.initials: DP
authors.lastname: Woldbye
authors.affiliation: Laboratory of Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark, and The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark (Mr Jensen, Ms Ratner, Dr Rudenko, Ms Skov, Ms Hundahl, and Dr Holst); Laboratory of Neural Plasticity, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark (Drs Christiansen and Woldbye). holst@sund.ku.dk.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Holst
mesh_terms: D000679:Amygdala / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001007:Anxiety / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control* / Q000523:psychology; D001522:Behavior, Animal / Q000187:drug effects*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D054439:Ghrelin / Q000494:pharmacology*; D019417:Hindlimb Suspension; D006801:Humans; D008124:Locomotion / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000187:drug effects; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D054440:Receptors, Ghrelin / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D012919:Social Behavior; D013315:Stress, Psychological / Q000150:complications / Q000378:metabolism / Q000523:psychology; D013550:Swimming; D013997:Time Factors
chemical_list: D014151:Anti-Anxiety Agents; D054439:Ghrelin; D054440:Receptors, Ghrelin; D044282:Receptor, Serotonin, 5-HT1A
keywords: amygdala; anxiety; ghrelin; rAAV; stress