Effect of Spectral Transmittance through Red-Tinted Rodent Cages on Circadian Metabolism and Physiology in Nude Rats

Light entrains normal circadian rhythms of physiology and metabolism in all mammals. Previous studies from our laboratory demonstrated that spectral transmittance (color) of light passing through cages affects these responses in rats. Here, we addressed the hypothesis that red tint alters the circad...

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Bibliographic Details
Published in:Journal of the American Association for Laboratory Animal Science 2013-11, Vol.52 (6), p.745-755
Main Authors: Dauchy, Robert T, Wren, Melissa A, Dauchy, Erin M, Hanifin, John P, Jablonski, Michael R, Warfield, Benjamin, Brainard, George C, Hill, Steven M, Mao, Lulu, Dupepe, Lynell M, Ooms, Tara G, Blask, David E
Format: Article
Language:English
Subjects:
Animals
Animals, Laboratory
Blood Glucose - analysis
Circadian Rhythm - radiation effects
Corticosterone - blood
Corticosterone - metabolism
Corticosterone - physiology
Female
Housing, Animal
Husbandry
Insulin - blood
Light
Melatonin - blood
Melatonin - metabolism
Rats
Rats, Nude - physiology
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Summary:Light entrains normal circadian rhythms of physiology and metabolism in all mammals. Previous studies from our laboratory demonstrated that spectral transmittance (color) of light passing through cages affects these responses in rats. Here, we addressed the hypothesis that red tint alters the circadian nocturnal melatonin signal and circadian oscillation of other metabolic and physiologic functions. Female nude rats (Hsd:RH-Foxn1rnu; n = 12 per group) were maintained on a 12:12-h light (300 lx; 123.0 μW/cm2; lights on 0600):dark regimen in standard polycarbonate translucent clear or red-tinted cages. After 1 wk, rats underwent 6 low-volume blood draws via cardiocentesis over a 4-wk period. Plasma melatonin levels were low during the light phase (1.0 ± 0.2 pg/mL) in rats in both types of cages but were significantly lower in red-tinted (105.0 ± 2.4 pg/mL) compared with clear (154.8 ± 3.8 pg/mL) cages during the dark. Normal circadian rhythm of plasma total fatty acid was identical between groups. Although phase relationships of circadian rhythms in glucose, lactic acid, pO2, and pCO2 were identical between groups, the levels of these analytes were lower in rats in red-tinted compared with clear cages. Circadian rhythms of plasma corticosterone, insulin, and leptin were altered in terms of phasing, amplitude, and duration in rats in red-tinted compared with clear cages. These findings indicate that spectral transmittance through red-colored cages significantly affects circadian regulation of neuroendocrine, metabolic, and physiologic parameters, potentially influencing both laboratory animal health and wellbeing and scientific outcomes.
ISSN:1559-6109