title: Altered expression of circadian rhythm genes among individuals with a history of depression.
abstract: BACKGROUND
  Depression has been associated with several circadian rhythm perturbations, suggesting a disruption of the circadian clock system in affective disorders. The interaction of several circadian clock genes generates these daily circadian rhythms.
  
  
  METHODS
  This cross-sectional study evaluated whether circadian gene expression differed between individuals with a history of depression and participants without a similar history. The participants were 60 healthy older adults. Half of the participants had a history of depression. Real-time quantitative polymerase chain reaction was used to measure the circadian gene Clock, BMAL1, Period1, and Period2 messenger RNA levels in peripheral blood leukocytes.
  
  
  RESULTS
  Individuals with a history of depression had higher Clock, Period1, and Bmal1 mRNA levels, compared to non-depressed participants.
  
  
  CONCLUSIONS
  Although circadian gene expression fluctuates throughout the day, clock gene mRNA levels were evaluated only in the morning.
  
  
  CONCLUSIONS
  These results suggest that disruptions of the molecular mechanisms underlying the circadian clock system may be associated with depression.
authors.affiliation: Department of Psychology, The Ohio State University, USA. gouin.1@osu.edu
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gouin
authors.forename: James
authors.initials: J
authors.lastname: Connors
authors.forename: Janice K
authors.initials: JK
authors.lastname: Kiecolt-Glaser
authors.forename: Ronald
authors.initials: R
authors.lastname: Glaser
authors.forename: William B
authors.initials: WB
authors.lastname: Malarkey
authors.forename: Cathie
authors.initials: C
authors.lastname: Atkinson
authors.forename: David
authors.initials: D
authors.lastname: Beversdorf
authors.forename: Ning
authors.initials: N
authors.lastname: Quan
mesh_terms: D056930:ARNTL Transcription Factors / Q000235:genetics; D000368:Aged; D056926:CLOCK Proteins / Q000235:genetics; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000235:genetics*; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000235:genetics*; D003865:Major Depressive Disorder / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D056950:Period Circadian Proteins / Q000235:genetics; D011569:Psychiatric Status Rating Scales; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D007319:Sleep Initiation and Maintenance Disorders / Q000235:genetics; D012959:Socioeconomic Factors
chemical_list: D056930:ARNTL Transcription Factors; C538960:BMAL1 protein, human; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D056926:CLOCK Proteins; C538943:CLOCK protein, human
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