Eliminating animal facility light-at-night contamination and its effect on circadian regulation of rodent physiology, tumor growth, and metabolism: a challenge in the relocation of a cancer research laboratory.

Jun 7, 2011Journal 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

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗

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.

AI simplified

Appropriate laboratory animal facility lighting and lighting protocols are essential for maintaining the health and wellbeing of laboratory animals and ensuring the credible outcome of scientific investigations. Our recent experience in relocating to a new laboratory facility illustrates the importance of these considerations. Previous studies in our laboratory demonstrated that animal room contamination with light-at-night (LAN) of as little as 0.2 lx at rodent eye level during an otherwise normal dark-phase disrupted host circadian rhythms and stimulated the metabolism and proliferation of human cancer xenografts in rats. Here we examined how simple improvements in facility design at our new location completely eliminated dark-phase LAN contamination and restored normal circadian rhythms in nontumor-bearing rats and normal tumor metabolism and growth in host rats bearing tissue-isolated MCF7(SR(-)) human breast tumor xenografts or 7288CTC rodent hepatomas. Reducing LAN contamination in the animal quarters from 24.5 ± 2.5 lx to nondetectable levels (complete darkness) restored normal circadian regulation of rodent arterial blood melatonin, glucose, total fatty and linoleic acid concentrations, tumor uptake of O(2), glucose, total fatty acid and CO(2) production and tumor levels of cAMP, triglycerides, free fatty acids, phospholipids, and cholesterol esters, as well as extracellular-signal-regulated kinase, mitogen-activated protein kinase, serine-threonine protein kinase, glycogen synthase kinase 3β, γ-histone 2AX, and proliferating cell nuclear antigen.

Eliminating animal facility light-at-night contamination and its effect on circadian regulation of rodent physiology, tumor growth, and metabolism: a challenge in the relocation of a cancer research laboratory.

Abstract

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

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