Light at night during development in mice has modest effects on adulthood behavior and neuroimmune activation

Light at night disrupts biological clocks, calendars, and immune function

“…Indeed male Swiss Webster mice housed in 5 lx ALAN for 4 weeks demonstrated elevated microglia pro-inflammatory cytokine expression (TNF and IL-6) following LPS administration [ 61 ]. Similar effects are seen in female C57Bl6 mice with exposure to ALAN during development and subsequent challenge with LPS in adulthood [ 62 ]. Furthermore, housing male Swiss Webster mice in 5 lx ALAN for 7 days following cardiac arrest resulted in an increase in CNS proinflammatory cytokine expression, elevated Iba1 immunoreactivity (a marker for microglial activation with concurrent cytokine data), and reduced survival [ 63 ].…”

Chronic circadian phase advance in male mice induces depressive-like responses and suppresses neuroimmune activation

“…Indeed, the hippocampus of female hamsters appears to be sensitive to CPA: female hamsters show long-term cognitive deficits 4 weeks after the cessation of phase shifts ( Gibson et al., 2010 ). We previously found that female mice during development are more susceptible to another chronic light manipulation, dim light at night, and exhibit affective behaviors and worsened neuroinflammatory responses to LPS ( Chen et al., 2021 ). Future studies should compare the potential sex differences in neuroinflammatory responses and mood-related behaviors after CPA.…”

“…3 μg of RNA was reverse transcribed to cDNA with SuperScriptII Reverse Transcriptase (Invitrogen) according to the manufacturer's protocol. Relative mRNA expressions of pro-inflammatory markers interleukin-1β ( Il1β ), Nfkbia (indicative of NFκB ), Tnf , microglia phagocytic marker Cd68 , anti-inflammatory gene arginase 1 (Arg 1 ), brain-derived neurotrophic factor ( Bdnf ), and circadian clock genes Per1 , Per2 , Nr1d1 , and Nr1d2 were determined relative to housekeeping gene Gapdh as previously described ( Chen et al., 2021 ). All genes were determined in duplicates, analyzed using the 2 ΔΔCt method, and normalized such that the level of the control ZT4 group was set to a value of 1.…”

“…Despite the SCN's role as the primary oscillator, circadian clocks exist in nearly every organ and tissue including peripheral organs such as the liver ( Tahara and Shibata, 2016 ), and in brain regions such as the hippocampus ( Debski et al., 2020 ). Specifically, the hippocampus is a brain region involved in emotional regulation ( Hajszan et al., 2010 ; Altar, 1999 ), it is sensitive to stress, glucocorticoids ( McEwen, 2008 ) and chronic light treatment ( Bedrosian et al., 2011 ; Chen et al., 2021 ), and diseases such as epilepsy reset hippocampal circadian oscillations ( Debski et al., 2020 ). Abrupt changes of external signals that are experienced during global travel or rotating shift work, including changes in timing of light exposure and food intake, may lead to desynchronization of internal circadian rhythms and cause mood disturbances ( Reinberg and Ashkenazi, 2008 ).…”

Chronic Exposure to Dim Light at Night or Irregular Lighting Conditions Impact Circadian Behavior, Motor Coordination, and Neuronal Morphology

“…A number of previous studies have demonstrated the impact DLAN has upon behavior. Specifically, exposure to DLAN has been shown to modulate mood and anxiety ( Bedrosian et al, 2011 , 2013 ; Aubrecht et al, 2013 ; Cisse et al, 2016 ; Chen et al, 2021 ), circadian function ( Shuboni and Yan, 2010 ) and sleep consolidation ( Panagiotou and Deboer, 2020 ; Panagiotou et al, 2020 ). Here, we confirm the long-term disruptive influence of DLAN upon circadian activity but also demonstrate an unexpected impact of the condition upon motor function.…”