title: Disrupted light-dark cycle induces obesity with hyperglycemia in genetically intact animals.
abstract: BACKGROUND
  The environmental light-dark (LD) cycle entrains the circadian clock located in the suprachiasmatic nucleus (SCN) of mammals. Recent studies of genetically impaired animals with clock gene mutations have revealed associations between metabolic disorders and the circadian clock. However, whether such disordered phenotypes are due to a loss of circadian clock function within specific metabolically relevant tissues, or the result of disrupted circadian behavioral activities governed by the SCN remains unknown.
  
  
  OBJECTIVE
  The present study examines the effect of disrupted LD cycles that might perturb the circadian clock in the SCN and peripheral organs on a high-fat/high-sucrose diet-induced obesity in genetically intact mice.
  
  
  METHODS
  The behavioral patterns of the mice were disturbed under an ultradian 3 h light-3 h dark cycle (LD 3:3) due to light-induced direct suppression of the behavior (masking effect).
  
  
  RESULTS
  Obesity with hyperglycemia was significantly enhanced and levels of hemoglobin A1c were significantly higher under LD 3:3 compared with LD 12:12.
  
  
  CONCLUSIONS
  These findings provide a link between metabolic disorders and the "environmental mutation" in genetically intact animals.
authors.affiliation: Clock Cell Biology Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan. k-ooishi@aist.go.jp
authors.forename: Katsutaka
authors.initials: K
authors.lastname: Oishi
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D019422:Dietary Sucrose / Q000494:pharmacology; D004327:Drinking Behavior / Q000502:physiology; D004435:Eating / Q000502:physiology; D006442:Glycated Hemoglobin / Q000378:metabolism; D006943:Hyperglycemia / Q000235:genetics / Q000503:physiopathology*; D008055:Lipids / Q000097:blood; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D017440:Photoperiod; D013493:Suprachiasmatic Nucleus / Q000502:physiology
chemical_list: D001786:Blood Glucose; D019422:Dietary Sucrose; D006442:Glycated Hemoglobin; D008055:Lipids