Light-at-night has become an increasing and essential part of the modern lifestyle and leads to a number of health problems, including excessive body mass index, cardiovascular diseases, diabetes, and cancer. The International Agency for Research on Cancer (IARC) Working Group concluded
that “shift-work that involves circadian disruption is probably carcinogenic to humans” (Group 2A) . According to the circadian disruption hypothesis, light-at-night might disrupt the endogenous circadian rhythm and specifically suppress nocturnal production of the pineal hormone
melatonin and its secretion into the blood. We evaluated the effect of various light/dark regimens on the survival, life span, and spontaneous and chemical carcinogenesis in rodents. Exposure to constant illumination was followed by accelerated aging and enhanced spontaneous tumorigenesis
in female CBA and transgenic HER-2/neu mice. In male and female rats maintained at various light/dark regimens (standard 12:12 light/dark [LD], the natural light [NL] of northwestern Russia, constant light [LL], and constant darkness [DD]) from the age of 25 days until natural death, it was
found that exposure to NL and LL regimens accelerated age-related switch-off of the estrous function (in females), induced development of metabolic syndrome and spontaneous tumorigenesis, and shortened life span both in male and females rats compared to the standard LD regimen. Melatonin given
in nocturnal drinking water prevented the adverse effect of the constant illumination (LL) and natural light (NL) regimens on the homeostasis, life span, and tumor development both in mice and rats. The exposure to the LL regimen accelerated colon carcinogenesis induced by 1,2-dimethylhydrazine
(DMH) in rats, whereas the treatment with melatonin alleviated the effects of LL. The maintenance of rats at the DD regimen inhibited DMH-induced carcinogenesis. The LL regimen accelerated, whereas the DD regimen inhibited both mammary carcinogenesis induced by N-nitrosomethylurea and transplacental
carcinogenesis induced by N-nitrosoethylurea in rats. Treatment with melatonin prevented premature aging and tumorigenesis in rodents. The data found in the literature and our observations suggest that the use of melatonin would be effective for cancer prevention in humans at risk as a result
of light pollution.
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Document Type: Research Article
December 1, 2012
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Current Aging Science publishes frontier review and experimental articles in all areas of aging and age-related research that may influence longevity. This multidisciplinary journal will help in understanding the biology and mechanism of aging, genetics, pathogenesis, intervention of normal aging process and preventive strategies of age-related disorders. The journal publishes objective reviews written by experts and leaders actively engaged in research using cellular, clinical, molecular, and animal models, including lower organism models (e.g., yeast, Caenorhabditis elegans and Drosophila). In addition to the affect of aging on integrated systems, the journal also covers original articles on recent research in fast emerging areas of adults stem cells, brain imaging, calorie restriction, immunosenescence, molecular diagnostics, pharmacology and clinical aspects of aging. Manuscripts are encouraged that relate to developmental programming of aging and the synergistic mechanism of aging with cardiovascular diseases, obesity and neurodegenerative disorders.
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