Dataset Information

Adaptation to experimental jet-lag in R6/2 mice despite circadian dysrhythmia.

ABSTRACT: The R6/2 transgenic mouse model of Huntington's disease (HD) shows a disintegration of circadian rhythms that can be delayed by pharmacological and non-pharmacological means. Since the molecular machinery underlying the circadian clocks is intact, albeit progressively dysfunctional, we wondered if light phase shifts could modulate the deterioration in daily rhythms in R6/2 mice. Mice were subjected to four x 4 hour advances in light onset. R6/2 mice adapted to phase advances, although angles of entrainment increased with age. A second cohort was subjected to a jet-lag paradigm (6 hour delay or advance in light onset, then reversal after 2 weeks). R6/2 mice adapted to the original shift, but could not adjust accurately to the reversal. Interestingly, phase shifts ameliorated the circadian rhythm breakdown seen in R6/2 mice under normal LD conditions. Our previous finding that the circadian period (tau) of 16 week old R6/2 mice shortens to approximately 23 hours may explain how they adapt to phase advances and maintain regular circadian rhythms. We tested this using a 23 hour period light/dark cycle. R6/2 mice entrained to this cycle, but onsets of activity continued to advance, and circadian rhythms still disintegrated. Therefore, the beneficial effects of phase-shifting are not due solely to the light cycle being closer to the tau of the mice. Our data show that R6/2 mice can adapt to changes in the LD schedule, even beyond the age when their circadian rhythms would normally disintegrate. Nevertheless, they show abnormal responses to changes in light cycles. These might be caused by a shortened tau, impaired photic re-synchronization, impaired light detection and/or reduced masking by evening light. If similar abnormalities are present in HD patients, they may suffer exaggerated jet-lag. Since the underlying molecular clock mechanism remains intact, light may be a useful treatment for circadian dysfunction in HD.

SUBMITTER: Wood NI

PROVIDER: S-EPMC3563662 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Adaptation to experimental jet-lag in R6/2 mice despite circadian dysrhythmia.

Wood Nigel I NI McAllister Catherine J CJ Cuesta Marc M Aungier Juliet J Fraenkel Eloise E Morton A Jennifer AJ

PloS one 20130204 2

The R6/2 transgenic mouse model of Huntington's disease (HD) shows a disintegration of circadian rhythms that can be delayed by pharmacological and non-pharmacological means. Since the molecular machinery underlying the circadian clocks is intact, albeit progressively dysfunctional, we wondered if light phase shifts could modulate the deterioration in daily rhythms in R6/2 mice. Mice were subjected to four x 4 hour advances in light onset. R6/2 mice adapted to phase advances, although angles of ...[more]

PMID: 23390510

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Project description:BackgroundEvidence suggests that circadian rhythm disorder is associated with a variety of gastrointestinal diseases, and the circadian rhythm plays a key role in maintaining the homeostasis of intestinal flora. The underlying mechanisms are still not completely identified. This study was aimed to explore whether jet lag-caused circadian disruption influences gut microbiome and its metabolites.MethodsMice were synchronized with 12-h light/dark cycles (control group) or subjected to daily 8-h advance of the light/dark cycle for every 3 days (jet-lagged group). Four months later, fecal samples and jejunal contents were collected and analyzed by 16S rRNA gene sequencing. In addition, fecal samples were subjected to metabolome analysis with ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS).ResultsThe results of 16s rRNA sequencing showed that chronic jet lag led to decreased microbial abundance, richness, and diversity in both feces and jejunal contents. ANOSIM analysis revealed significant difference between control and jet-lagged groups. As the colonic microbiome, the abundance of Bacteroidetes phylum was significantly decreased and that of Actinobacteria phylum was increased in jet-lagged mice. Jet lag increased the ratio of Firmicutes to Bacteroidetes, an indicator for the imbalance of gut microbiota. Metabolome analysis of fecal samples showed that the levels of tryptophan and its derivatives were decreased in jet-lagged mice. In addition, fecal levels of secondary bile acids changed under jet lag conditions. Correlation analysis identified associations between tryptophan (and its derivatives) levels and colonic microbiota.ConclusionsThis study presents a comprehensive landscape of gut microbiota and its metabolites in mice subjected to chronic jet lag. The results suggest that circadian disruption may lead to changes in fecal and jejunal microbiota and fecal metabolites. Moreover, our results demonstrate a novel interplay between the gut microbiome and metabolome.

Dataset Information

Adaptation to experimental jet-lag in R6/2 mice despite circadian dysrhythmia.

Publications

Adaptation to experimental jet-lag in R6/2 mice despite circadian dysrhythmia.

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