Editors' ChoiceMedical Devices

Eating at the right time

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Science Translational Medicine  06 Jan 2016:
Vol. 8, Issue 320, pp. 320ec3
DOI: 10.1126/scitranslmed.aad9763

Shift work—including residency training for physicians—can be a grueling experience; there is little time for meals, sleep, and life outside the job. Recent data, albeit from mice, shed light on the detrimental effects that shift work combined with misaligned feeding schedules may have on learning and memory. Loh and colleagues gave one group of mice access to food only during mouse scheduled sleep times and another group access during mouse wakeful hours; the investigators then evaluated and compared the learning and memory abilities of the groups.

Although the feeding-aligned mice (received food while active) and feeding-misaligned mice (received food while inactive) maintained the same body weight, their circadian clocks were altered. The authors examined the animals’ clocks in ex vivo cultures of cells from the hippocampus, suprachiasmatic nucleus (SCN), and liver of mice carrying a reporter of circadian phase (PER2::LUC). Misaligned feeding did not alter the circadian phase of the master circadian clock in the SCN, which is responsible for controlling overall circadian rhythms, but did alter the phase in both tissue-specific clocks, in hippocampus and liver. To evaluate learning and memory in the feeding-aligned and -misaligned mice, the authors then trained the animals to associate a novel context with a fearful stimulus. Although both groups showed freezing behavior (fear) during the training trial, 24 hours later the misaligned mice were no longer as fearful, supporting the conclusion that misalignment has adverse effects on long-term memory. Further testing of the animals’ ability to recognize novel objects revealed that the misaligned mice were less able to perform this task during nighttime tests, indicating that they suffered a decrease in cognitive performance. Getting enough ZZZZ’s and eating at the right time seem to be essential for mice, and perhaps also for shift workers operating life-saving or life-threatening equipment!

D. H.-W. Loh et al., Misaligned feeding impairs memories. eLife 10.7554/eLife.09460 (2015). [Full Text]

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