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Yonis M, Haim A, Zubidat AE. Altered metabolic and hormonal responses in male rats exposed to acute bright light-at-night associated with global DNA hypo-methylation. J Photochem Photobiol B 2019; 194:107-118. [PMID: 30953912 DOI: 10.1016/j.jphotobiol.2019.03.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 03/18/2019] [Accepted: 03/27/2019] [Indexed: 12/17/2022]
Abstract
The association between light pollution and disruption of daily rhythms, metabolic and hormonal disorders, as well as cancer progression is well-recognized. These adverse effects could be due to nocturnal melatonin suppression. The signaling pathway by which light pollution affects metabolism and endocrine responses is unclear. We studied the effects of artificial light at night (ALAN1) on body mass, food and water intake, daily rhythms of body temperature, serum glucose and insulin in male rats. Daily rhythms of urine production and urinary 6-sulfatoxymelatonin (6-SMT2), as well as global DNA methylation in pancreas and liver tissues were also assessed. Mass gain was higher in ALAN rats compared with controls. Food intake, water consumption, glucose, insulin, and 6-SMT levels markedly lessened in response to ALAN. Conversely, urine production and body temperature were elevated in ALAN rats compared with controls. Significant 24-h rhythms were detected for all variables that were altered in mesor, amplitude, and acrophase occurrences under ALAN conditions. DNA hypo-methylation was detected in ALAN pancreatic tissue compared with controls, but not in hepatic tissue. Overall, ALAN affects metabolic and hormonal physiology in different levels in which flexible crosstalk between melatonin and both epigenetics and metabolic levels expressed as body temperature rhythm, is suggested to mediate the environmental exposure at the molecular level and subsequently physiology is altered. The flexibility of epigenetic modifications provides a potential therapeutic target for rectifying ALAN adverse effects by epigenetic markers such as melatonin and behavioral lifestyle interventions for confining ALAN exposures as much as possible.
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Affiliation(s)
- Mohamad Yonis
- Department of Human Biology, University of Haifa, Mount Carmel, Haifa 3498838, Israel
| | - Abraham Haim
- The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Mount Carmel, Haifa 3498838, Israel.
| | - A Elsalam Zubidat
- The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Mount Carmel, Haifa 3498838, Israel.
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Zubidat AE, Fares B, Fares F, Haim A. Artificial Light at Night of Different Spectral Compositions Differentially Affects Tumor Growth in Mice: Interaction With Melatonin and Epigenetic Pathways. Cancer Control 2019; 25:1073274818812908. [PMID: 30477310 PMCID: PMC6259078 DOI: 10.1177/1073274818812908] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
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.
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Affiliation(s)
- A E Zubidat
- 1 The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Haifa, Israel
| | - B Fares
- 2 Department of Human Biology, University of Haifa, Haifa, Israel.,3 Department of Molecular Genetics, Carmel Medical Center, Haifa, Israel
| | - F Fares
- 2 Department of Human Biology, University of Haifa, Haifa, Israel.,3 Department of Molecular Genetics, Carmel Medical Center, Haifa, Israel
| | - A Haim
- 1 The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Haifa, Israel
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Asher A, Shabtay A, Brosh A, Eitam H, Agmon R, Cohen-Zinder M, Zubidat AE, Haim A. "Chrono-functional milk": The difference between melatonin concentrations in night-milk versus day-milk under different night illumination conditions. Chronobiol Int 2015; 32:1409-16. [PMID: 26588495 DOI: 10.3109/07420528.2015.1102149] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
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.
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Affiliation(s)
- A Asher
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and.,b Department of Evolutionary and Environmental Biology , Faculty of Natural Sciences, The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa , Mount Carmel , Haifa , Israel
| | - A Shabtay
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and
| | - A Brosh
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and
| | - H Eitam
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and
| | - R Agmon
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and
| | - M Cohen-Zinder
- a Agricultural Research Organization , Newe Ya'ar, Ramat Yishay , Israel and
| | - A E Zubidat
- b Department of Evolutionary and Environmental Biology , Faculty of Natural Sciences, The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa , Mount Carmel , Haifa , Israel
| | - A Haim
- b Department of Evolutionary and Environmental Biology , Faculty of Natural Sciences, The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa , Mount Carmel , Haifa , Israel
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