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Author (up) Aubrecht, T.; Weil, Z.; Nelson, R. url  doi
openurl 
  Title Dim light at night interferes with the development of the short-day phenotype and impairs cell-mediated immunity in Siberian hamsters (Phodopus sungorus) Type Journal Article
  Year 2014 Publication Journal of Experimental Zoology Abbreviated Journal J. Exp. Zool.  
  Volume 321 Issue 8 Pages 450-456  
  Keywords animals; seasonal timing; chronobiological effects  
  Abstract Winter is a challenging time to survive and breed outside of the tropics. Animals use day length (photoperiod) to regulate seasonally appropriate adaptations in anticipation of challenging winter conditions. The net result of these photoperiod-mediated adjustments is enhanced immune function and increased survival. Thus, the ability to discriminate day length information is critical for survival and reproduction in small animals. However, during the past century, urban and suburban development has rapidly expanded and filled the night sky with light from various sources, obscuring crucial light-dark signals, which alters physiological interpretation of day lengths. Furthermore, reduced space, increased proximity to people, and the presence of light at night may act as stressors for small animals. Whereas acute stressors typically enhance immune responses, chronic exposure to stressors often impairs immune responses. Therefore, we hypothesized that the combination of dim light at night and chronic stress interferes with enhanced cell-mediated immunity observed during short days. Siberian hamsters (Phodopus sungorus) were assigned to short or long days with dark nights (0 lux) or dim (5 lux) light at night for 10 weeks. Following 2 weeks of chronic restraint (6 hr/day), a model of chronic stress, delayed type hypersensitivity (DTH) responses were assessed. Both dim light at night and restraint reduced the DTH response. Dim light at night during long nights produced an intermediate short day phenotype. These results suggest the constant presence of light at night could negatively affect survival of photoperiodic rodents by disrupting the timing of breeding and immune responses.  
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  Notes Approved no  
  Call Number LoNNe @ schroer @ Serial 1574  
Permanent link to this record
 

 
Author (up) Bedrosian, Tracy A; Fonken, Laura K; Walton, James C; Haim, Abraham; Nelson, Randy J url  doi
openurl 
  Title Dim light at night provokes depression-like behaviors and reduces CA1 dendritic spine density in female hamsters Type Journal Article
  Year 2011 Publication Psychoneuroendocrinology Abbreviated Journal  
  Volume 36 Issue 7 Pages 1062-1069  
  Keywords animals; Chronobiological effects; Behavior  
  Abstract The prevalence of major depression has increased in recent decades; however, the underlying causes of this phenomenon remain unspecified. One environmental change that has coincided with elevated rates of depression is increased exposure to artificial light at night. Shift workers and others chronically exposed to light at night are at increased risk of mood disorders,suggesting that nighttime illumination may influence brain mechanisms mediating affect. We tested the hypothesis that exposure to dim light at night may impact affective responses and alter morphology of hippocampal neurons. Ovariectomized adult female Siberian hamsters (Phodopus sungorus) were housed for 8 weeks in either a light/dark cycle (LD) or a light/dim light cycle (DM), and then behavior was assayed. DM-hamsters displayed more depression-like responses in the forced swim and the sucrose anhedonia tests compared with LD-hamsters. Conversely, in the elevated plus maze DM-hamsters reduced anxiety-like behaviors. Brains from the same animals were processed using the Golgi-Cox method and hippocampal neurons within CA1, CA3, and the dentate gyrus were analyzed for morphological characteristics. In CA1, DM-hamsters significantly reduced dendritic spine density on both apical and basilar dendrites, an effect which was not mediated by baseline cortisol, as concentrations were equivalent between groups. These results demonstrate dim light at night is sufficient to reduce synaptic spine connections to CA1. Importantly, the present results suggest that night-time low level illumination, comparable to levels that are pervasive in North America and Europe, may contribute to the increasing prevalence of mood disorders.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ schroer @ Serial 1576  
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Author (up) Bray, M.S.; Young, M.E. url  doi
openurl 
  Title Chronobiological Effects on Obesity Type Journal Article
  Year 2012 Publication Current Obesity Reports Abbreviated Journal Curr Obes Rep  
  Volume 1 Issue 1 Pages 9-15  
  Keywords Human Health; Chronobiological effects; Circadian; Gene; Molecular clock; Obesity; Rhythm; Shift work; Sleep; Transcription  
  Abstract The development of obesity is the consequence of a multitude of complex interactions between both genetic and environmental factors. It has been suggested that the dramatic increase in the prevalence of obesity over the past 30 years has been the result of environmental changes that have enabled the full realization of genetic susceptibility present in the population. Among the many environmental alterations that have occurred in our recent history is the ever-increasing dyssynchrony between natural cycles of light/dark and altered patterns of sleep/wake and eating behavior associated with our “24-hour” lifestyle. An extensive research literature has established clear links between increased risk for obesity and both sleep deprivation and shift work, and our understanding of the consequences of such dyssynchrony at the molecular level is beginning to emerge. Studies linking alterations in cellular circadian clocks to metabolic dysfunction point to the increasing importance of chronobiology in obesity etiology.  
  Address Departments of Epidemiology and Genetics, University of Alabama at Birmingham, Birmingham, AL  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2162-4968 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23682347; PMCID:PMC3653336 Approved no  
  Call Number LoNNe @ christopher.kyba @ Serial 510  
Permanent link to this record
 

 
Author (up) Bray, M.S.; Young, M.E. url  doi
openurl 
  Title Chronobiological Effects on Obesity Type Journal Article
  Year 2012 Publication Current Obesity Reports Abbreviated Journal Curr Obes Rep  
  Volume 1 Issue 1 Pages 9-15  
  Keywords Human Health; Chronobiological effects; Circadian; Gene; Molecular clock; Obesity; Rhythm; Shift work; Sleep; Transcription  
  Abstract The development of obesity is the consequence of a multitude of complex interactions between both genetic and environmental factors. It has been suggested that the dramatic increase in the prevalence of obesity over the past 30 years has been the result of environmental changes that have enabled the full realization of genetic susceptibility present in the population. Among the many environmental alterations that have occurred in our recent history is the ever-increasing dyssynchrony between natural cycles of light/dark and altered patterns of sleep/wake and eating behavior associated with our “24-hour” lifestyle. An extensive research literature has established clear links between increased risk for obesity and both sleep deprivation and shift work, and our understanding of the consequences of such dyssynchrony at the molecular level is beginning to emerge. Studies linking alterations in cellular circadian clocks to metabolic dysfunction point to the increasing importance of chronobiology in obesity etiology.  
  Address Departments of Epidemiology and Genetics, University of Alabama at Birmingham, Birmingham, AL  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2162-4968 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:23682347; PMCID:PMC3653336 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 725  
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