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1.
Cancer Control ; 25(1): 1073274818812908, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30477310

RESUMO

Lighting technology is rapidly advancing toward shorter wavelength illuminations that offer energy-efficient properties. Along with this advantage, the increased use of such illuminations also poses some health challenges, particularly breast cancer progression. Here, we evaluated the effects of artificial light at night (ALAN) of 4 different spectral compositions (500-595 nm) at 350 Lux on melatonin suppression by measuring its urine metabolite 6-sulfatoxymelatonin, global DNA methylation, tumor growth, metastases formation, and urinary corticosterone levels in 4T1 breast cancer cell-inoculated female BALB/c mice. The results revealed an inverse dose-dependent relationship between wavelength and melatonin suppression. Short wavelength increased tumor growth, promoted lung metastases formation, and advanced DNA hypomethylation, while long wavelength lessened these effects. Melatonin treatment counteracted these effects and resulted in reduced cancer burden. The wavelength suppression threshold for melatonin-induced tumor growth was 500 nm. These results suggest that short wavelength increases cancer burden by inducing aberrant DNA methylation mediated by the suppression of melatonin. Additionally, melatonin suppression and global DNA methylation are suggested as promising biomarkers for early diagnosis and therapy of breast cancer. Finally, ALAN may manifest other physiological responses such as stress responses that may challenge the survival fitness of the animal under natural environments.


Assuntos
Epigênese Genética/efeitos da radiação , Iluminação/efeitos adversos , Neoplasias Pulmonares/epidemiologia , Neoplasias Mamárias Experimentais/etiologia , Melatonina/metabolismo , Animais , Linhagem Celular Tumoral/transplante , Corticosterona/urina , Metilação de DNA/efeitos da radiação , Feminino , Humanos , Neoplasias Pulmonares/secundário , Neoplasias Pulmonares/urina , Neoplasias Mamárias Experimentais/patologia , Neoplasias Mamárias Experimentais/urina , Melatonina/administração & dosagem , Melatonina/análogos & derivados , Melatonina/urina , Camundongos , Camundongos Endogâmicos BALB C , Fotoperíodo
2.
Chronobiol Int ; 32(10): 1409-16, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26588495

RESUMO

Pineal melatonin (MLT) is produced at highest levels during the night, under dark conditions. We evaluated differences in MLT-concentration by comparing daytime versus night time milk samples, from two dairy farms with different night illumination conditions: (1) natural dark (Dark-Night); (2) short wavelength Artificial Light at Night (ALAN, Night-Illuminated). Samples were collected from 14 Israeli Holstein cows from each commercial dairy farm at 04:30 h ("Night-milk") 12:30 h ("Day-milk") and analyzed for MLT-concentration. In order to study the effects of night illumination conditions on cows circadian rhythms, Heart Rate (HR) daily rhythms were recorded. MLT-concentrations of Night-milk samples from the dark-night group were significantly (p < 0.001) higher than those of Night-illuminated conditions (30.70 ± 1.79 and 17.81 ± 0.33 pg/ml, respectively). Interestingly, night illumination conditions also affected melatonin concentrations at daytime where under Dark-Night conditions values are significantly (p < 0.001) higher than Night-Illuminated conditions, (5.36 ± 0.33 and 3.30 ± 0.18 pg/ml, respectively). There were no significant differences between the two treatments in the milk yield and milk composition except somatic cell count (SCC), which was significantly lower (p = 0.02) in the Dark-Night group compared with the Night-Illuminated group. Cows in both groups presented a significant (p < 0.01) HR daily rhythm, therefore we assume that in the night illuminated cows feeding and milking time are the "time keeper", while in the Dark-night cows, HR rhythms were entrained by the light/dark cycle. The higher MLT-concentration in Dark-night cows with the lower SCC values calls upon farmers to avoid exposure of cows to ALAN. Therefore, under Dark-night conditions milk quality will improve by lowering SCC values where separation between night and day of such milk can produce chrono-functional milk, naturally rich with MLT.


Assuntos
Comportamento Animal/fisiologia , Ritmo Circadiano/fisiologia , Iluminação , Melatonina/metabolismo , Leite , Fotoperíodo , Animais , Bovinos , Feminino , Luz , Glândula Pineal/metabolismo
3.
J Exp Biol ; 212(Pt 23): 3857-64, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19915128

RESUMO

Photoperiod is an important cue regulating biological rhythms in mammals, including 'blind' subterranean and sighted fossorial rodent species. These species may respond differentially to changes in light quality according to their retinal complexity. The effects of increasing light intensity on daily rhythms of urine excretion and urinary output of 6-sulfatoxymelatonin levels were compared in 'blind' mole rats Spalax ehrenbergi and sighted social voles, Microtus socialis. Our results show that the threshold irradiance required to entrain rhythms of voles is three magnitudes greater than that for mole rats. The results suggest that mole rats have an operational photoreceptive pathway with a lower threshold irradiance than voles. Such a low threshold reflects the remarkable capability of this 'blind' species to utilize light signals even under challenging light conditions.


Assuntos
Arvicolinae/fisiologia , Ritmo Circadiano/fisiologia , Luz , Fotoperíodo , Spalax/fisiologia , Análise de Variância , Animais , Masculino , Melatonina/análogos & derivados , Melatonina/urina , Especificidade da Espécie , Micção/efeitos da radiação
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