title: Increased anxiety but normal fear and safety learning in orexin-deficient mice.
abstract: The loss of orexin neurons in humans leads to the disease narcolepsy, characterized by daytime sleepiness and cataplexy. Recent data suggest that orexin is also involved in emotional processing. The goal of the present study was to evaluate fear and safety learning as well as unconditioned fear (anxiety) in orexin-deficient animals. Orexin-deficient mice are an established animal model used to investigate the neuropathology and potential treatments for narcolepsy. Here, we present novel data showing that orexin-deficient mice express increased anxiety in the open field, light-dark box test and carnivore odor-induced avoidance, but are normal in fear and safety learning. These findings suggest an important role of orexin in brain areas involved in anxiety.
authors.affiliation: Institute for Pharmacology and Toxicology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.
authors.forename: Radwa
authors.initials: R
authors.lastname: Khalil
authors.affiliation: Institute for Pharmacology and Toxicology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany; Center of Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, Germany. Electronic address: markus.fendt@med.ovgu.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Fendt
mesh_terms: D000221:Adaptation, Ocular / Q000235:genetics; D000818:Animals; D001007:Anxiety / Q000235:genetics* / Q000503:physiopathology; D001362:Avoidance Learning / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology; D004558:Electric Stimulation / Q000009:adverse effects; D005106:Exploratory Behavior / Q000502:physiology; D005239:Fear / Q000523:psychology; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009812:Odorants; D000068797:Orexins / Q000172:deficiency* / Q000235:genetics
chemical_list: D000068797:Orexins
keywords: Hypocretin; Light-dark box; Locomotor activity; Open field; Predator odor avoidance; Unconditioned fear