Circadian rhythm bifurcation induces flexible phase resetting by reducing circadian amplitude

Jul 26, 2018The European journal of neuroscience

Splitting the internal body clock leads to flexible timing by lowering its strength

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Behavioral jet lag after simulated time-zone travel is virtually eliminated following bifurcated circadian entrainment under a novel 24-h light:dark:light:dark (LDLD) cycle.

The suprachiasmatic nucleus (SCN) and peripheral tissues exhibit changes in oscillatory stability when exposed to the LDLD cycle.
Dissection as a resetting stimulus resulted in a stronger phase setting of cultured tissues under LDLD compared to a normal light:dark cycle.
Acute bioluminescence analysis revealed reduced rhythm amplitude and altered phase of the PER2 gene in SCN explants under LDLD.
Significant reductions in amplitude and rhythmicity of clock genes were observed in the lung, liver, and kidney when analyzed in vivo under LDLD.
Spatiotemporal patterns of PER2 peak times in cultured SCN were altered in the LDLD condition.

AI simplified

Shift-work and jet-lag-related disorders are caused by the limited flexibility of the suprachiasmatic nucleus (SCN), a master circadian clock in the hypothalamus, to adjust to new light-dark (LD) cycles. Recent findings confirmed here establish that behavioral jet lag after simulated time-zone travel is virtually eliminated following bifurcated circadian entrainment under a novel and atypical 24-h light:dark:light:dark (LDLD) cycle. To investigate the mechanisms of this fast resetting, we examined the oscillatory stability of the SCN and peripheral tissues in LDLD-bifurcated mice employing the dissection procedure as a perturbing resetting stimulus. SCN, lung, liver, and adrenal tissue were extracted at times throughout the day from female and male PER2::Luciferase knock-in mice entrained to either LDLD or a normal LD cycle. Except for adrenals, the phase of the cultured explants was more strongly set by dissection under LDLD than under normal LD. Acute bioluminescence levels of SCN explants indicate that the rhythm amplitude of PER2 is reduced and phase is altered in LDLD. Real-time quantitative PCR suggests that amplitude and rhythmicity of canonical clock genes in the lung, liver, and kidney are also significantly reduced in LDLD in vivo. Furthermore, spatiotemporal patterns of PER2 peak time in cultured SCN were altered in LDLD. These results suggest that altered gene expression patterns in the SCN caused by bifurcation likely result in fast resetting of behavior and cultured explants, consistent with previously reported mathematical models. Thus, non-invasive, simple light manipulations can make circadian rhythms more adaptable to abrupt shifts in the environmental LD cycle.

Full Text

Full text is available at the source.

View full text (PDF) ↗View full text (XML) ↗View full text ↗

Circadian rhythm bifurcation induces flexible phase resetting by reducing circadian amplitude

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief