title: Chronic Stress Induces Brain Region-Specific Alterations of Molecular Rhythms that Correlate with Depression-like Behavior in Mice.
abstract: BACKGROUND
  Emerging evidence implicates circadian abnormalities as a component of the pathophysiology of major depressive disorder (MDD). The suprachiasmatic nucleus (SCN) of the hypothalamus coordinates rhythms throughout the brain and body. On a cellular level, rhythms are generated by transcriptional, translational, and posttranslational feedback loops of core circadian genes and proteins. In patients with MDD, recent evidence suggests reduced amplitude of molecular rhythms in extra-SCN brain regions. We investigated whether unpredictable chronic mild stress (UCMS), an animal model that induces a depression-like physiological and behavioral phenotype, induces circadian disruptions similar to those seen with MDD.
  
  
  METHODS
  Activity and temperature rhythms were recorded in C57BL/6J mice before, during, and after exposure to UCMS, and brain tissue explants were collected from Period2 luciferase mice following UCMS to assess cellular rhythmicity.
  
  
  RESULTS
  UCMS significantly decreased circadian amplitude of activity and body temperature in mice, similar to findings in MDD patients, and these changes directly correlated with depression-related behavior. While amplitude of molecular rhythms in the SCN was decreased following UCMS, surprisingly, rhythms in the nucleus accumbens (NAc) were amplified with no changes seen in the prefrontal cortex or amygdala. These molecular rhythm changes in the SCN and the NAc also directly correlated with mood-related behavior.
  
  
  CONCLUSIONS
  These studies found that circadian rhythm abnormalities directly correlate with depression-related behavior following UCMS and suggest a desynchronization of rhythms in the brain with an independent enhancement of rhythms in the NAc.
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Logan
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Nicole
authors.initials: N
authors.lastname: Edgar
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Gillman
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hoffman
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Xiyu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Psychiatry and Translational Neuroscience Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.. Electronic address: mcclungca@upmc.edu.
authors.forename: Colleen A
authors.initials: CA
authors.lastname: McClung
mesh_terms: D000818:Animals; D001007:Anxiety / Q000378:metabolism; D001831:Body Temperature; D003865:Major Depressive Disorder / Q000378:metabolism*; D004195:Disease Models, Animal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity; D009714:Nucleus Accumbens / Q000378:metabolism*; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism*; D013315:Stress, Psychological / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*
chemical_list: D056950:Period Circadian Proteins
keywords: Amplitude; Chronic stress; Circadian; Depression; LumiCycle; Period2