title: Sex-specific diurnal immobility induced by forced swim test in wild type and clock gene deficient mice.
abstract: OBJECTIVE
  The link between alterations in circadian rhythms and depression are well established, but the underlying mechanisms are far less elucidated. We investigated the circadian characteristics of immobility behavior in wild type (WT) mice and mice with mutations in core Clock genes.
  
  
  METHODS
  All mice were tested with forced swim test (FST) at 4 h intervals.
  
  
  RESULTS
  These experiments revealed significant diurnal rhythms associated with immobility behavior in both male and female WT mice with sex-different circadian properties. In addition, male mice showed significantly less immobility during the night phase in comparison to female mice. Female Per1Brdm1 mice also showed significant rhythmicity. However, the timing of rhythmicity was very different from that observed in female wild type mice. Male Per1Brdm1 mice showed a pattern of rhythmicity similar to that of wild type mice. Furthermore, female Per1Brdm1 mice showed higher duration of immobility in comparison to male Per1Brdm1 mice in both daytime and early night phases. Neither Per2Brdm1 nor ClockΔ19 mice showed significant rhythmicity, but both female Per2Brdm1 and ClockΔ19 mice had lower levels of immobility, compared to males.
  
  
  CONCLUSIONS
  This study highlights the differences in the circadian characteristics of immobility induced by FST in WT, ClockΔ19, Per1, and Per2 deficient mice.
authors: Key Lab of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. yueyue1989825@sohu.com.
authors: Ningyue
authors: N
authors: Li
authors: Key Lab of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. xuyanhua.stu@hotmail.com.
authors: Yanhua
authors: Y
authors: Xu
authors: Key Lab of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. cxj2013@gmail.com.
authors: Xiaojuan
authors: X
authors: Chen
authors: Key Lab of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. duanq@psych.ac.cn.
authors: Qing
authors: Q
authors: Duan
authors: Key Lab of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. zhaomei@psych.ac.cn.
authors: Mei
authors: M
authors: Zhao
mesh_terms: D000818:Animals; D056926:CLOCK Proteins / Q000235:genetics*; D002940:Circadian Rhythm; D005260:Female; D008297:Male; D051379:Mice; D009154:Mutation; D056950:Period Circadian Proteins / Q000235:genetics; D012737:Sex Factors; D013550:Swimming / Q000502:physiology*
chemical_list: C539023:Per1 protein, mouse; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D056926:CLOCK Proteins; C538944:Clock protein, mouse