Phase-delay in the light-dark cycle impairs clock gene expression and levels of serotonin, norepinephrine, and their metabolites in the mouse hippocampus and amygdala

Shunpei Moriya, Yu Tahara, Hiroyuki Sasaki, Jun Ishigooka, Shigenobu Shibata

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Objective: A number of animal studies have implicated circadian clock genes in the regulation of mood, anxiety, and reward. However, the effect of misalignment of the environmental light-dark and internal circadian clock on the monoamine system is not fully understood. In the present study, we examined whether an abnormal light-dark schedule would affect behavior-, circadian clock-, and monoamine-related gene expressions, along with monoamine contents in the amygdala and hippocampus of mice. Methods: Mice were subjected to an 8-hour phase delay in the light-dark cycle (Shift) every two days for four weeks, and locomotor activity was continuously measured. We examined the circadian expression of clock genes (Per1, Per2, and Bmal1) and genes of the NE/5HT uptake transporters (. Net and Sert). In addition, the levels of NE/5HT and their metabolites MHPG/5HIAA were analyzed in the amygdala and hippocampus. Results: Locomotor activity showed a free-running phenotype with a longer period (>24 hours) and showed misalignment between the light-dark and inactive-active cycles. The amplitude of the day-night fluctuation of Bmal1 expression was reduced in the amygdala and hippocampus of light-dark-shifted mice. Net gene expression in the Shift group showed different profiles compared with the Control group. In addition, NE and 5HT levels in the amygdala of the Shift group increased during the active period. Conclusions: The present results suggest that misalignment of the internal and external clocks by continuous shifting of the light-dark amygdala and hippocampus of mice.

Original languageEnglish
Article number2844
Pages (from-to)1352-1359
Number of pages8
JournalSleep Medicine
Volume16
Issue number11
DOIs
Publication statusPublished - 2015 Nov 1

Keywords

  • Amygdala
  • Circadian rhythm
  • Locomotor activity
  • Monoamine
  • Phase delay

ASJC Scopus subject areas

  • Medicine(all)

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