Journal of the American Association for Laboratory Animal Science : JAALAS

Removing nighttime light pollution in animal rooms and its effects on daily body rhythms, tumor growth, and metabolism in rodents during cancer lab relocation

Circadian Biology Weekly Brief ↗PubMed ↗

Updated

Abstract

Reducing light-at-night contamination from 24.5 ± 2.5 lx to nondetectable levels restored normal circadian regulation in laboratory rats.

  • Light-at-night exposure of 0.2 lx can disrupt circadian rhythms and stimulate cancer metabolism in rats.
  • Improvements in facility design eliminated dark-phase light contamination, restoring normal circadian rhythms in nontumor-bearing rats.
  • Normal tumor metabolism and growth were observed in rats bearing human breast tumor xenografts and rodent hepatomas after eliminating light exposure.
  • Circadian regulation of arterial blood melatonin, glucose, and fatty acid concentrations was restored with complete darkness in animal quarters.
  • Tumor metabolic processes, including oxygen and glucose uptake, were normalized in the absence of light-at-night exposure.

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