Rodent of the Week: fixing jet lag and circadian rhythm disorders

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When our circadian rhythms are thrown out of whack -- either by jet travel, shift work or sleeplessness -- our bodies object, according to a wealth of emerging research. The risk of breast cancer, stroke and heart disease rise in shift workers, for example. Finding a way to restore circadian rhythms would not only be helpful to travelers fatigued from jet lag, it could lead to a reduction in disease risk.

A new animal study highlights an interesting approach to the problem. Researchers at the Max Planck Institute for Biophysical Chemistry in Germany used mice that were subjected to jet lag and circadian rhythm disruption (by altering the light and dark cycles they were exposed to). The researchers found that the ‘clock’ genes that are important to reestablishing normal circadian rhythms varies among different organs, such as the kidneys, liver, pancreas and adrenal gland. Further, the workings of the adrenal gland appear to coordinate circadian rhythms by gradually adjusting the release of adrenal hormones, called adrenal glucocorticoids.

‘...the adrenal gland has a special role,’ in returning the circadian rhythms back into their proper alignment, the authors wrote.

The findings suggest a possible approach to treating jet lag and circadian rhythm disorders through the use of corticosteroids.

‘Our study thus not only substantiated the importance of glucocorticoid rhythms in jet lag adaptation, but also established an informative experimental animal model to explore the treatment of jet lag and its associated symptoms,’ they wrote.

A medication called metyrapone, used to treat adrenal insufficiency, could be investigated in humans for treating jet lag.

The study ‘takes us to a new level of understanding of the molecular control of the resetting of the multitude of internal biological clocks disrupted in a mouse model of jet lag,’ said the author of a commentary accompanying the study.

The study was released this week in The Journal of Clinical Investigation.

-- Shari Roan