Newport Margaret E, Wilson Paul, Lowes Shanna, Behrends Marthe, Coons Alexis, Bowman Jeff, Bates Holly E
Department of Biology Trent University Peterborough Ontario Canada.
Wildlife Research and Monitoring Section Ontario Ministry of Natural Resources Peterborough Ontario Canada.
FASEB Bioadv. 2025 Apr 17;7(5):e70006. doi: 10.1096/fba.2024-00115. eCollection 2025 May.
Physiology is closely synchronized to daily and seasonal light/dark cycles. Humans artificially extend daylight and experience irregular light schedules, resulting in dysregulation of metabolism and body mass. In rodents, winter-like conditions (cold and short photoperiod) can alter energy balance and adipose tissue mass. To determine if photoperiod alone, independent of temperature, is a strong enough signal to regulate adiposity, we compared the effects of long and short photoperiod at thermoneutrality on adiposity and WAT gene expression in photoperiod-sensitive, F1 generation wild-derived adult male white-footed mice (). Mice were housed in long-day (16:8 light:dark) or short-day (8:16 light:dark) photoperiod conditions at thermoneutrality (27°C) for 4 weeks with the extended light being provided through artificial lighting. Photoperiod did not impact body weight or calorie consumption. However, mice housed in long photoperiod with extended artificial light selectively developed greater visceral WAT mass without changing subcutaneous WAT or interscapular BAT mass. This was accompanied by a decrease in and mRNA expression in visceral WAT with no change in , , or . Expression of , , and mRNA in visceral WAT differed between long and short photoperiods over time when aligned to circadian time but not onset of darkness, indicating alterations in clock gene expression with photoperiod. These findings suggest that extended photoperiod through artificial light can promote visceral fat accumulation alone, independent of temperature, supporting that artificial light may play a role in obesity.
生理学与日常和季节性的光/暗周期密切同步。人类人为地延长了白昼时间并经历不规律的光照时间表，从而导致新陈代谢和体重失调。在啮齿动物中，类似冬季的条件（寒冷和短光周期）会改变能量平衡和脂肪组织质量。为了确定仅光周期（独立于温度）是否是调节肥胖的足够强的信号，我们比较了在热中性条件下长光周期和短光周期对光周期敏感的F1代野生成年雄性白足鼠肥胖和白色脂肪组织（WAT）基因表达的影响。小鼠被饲养在热中性（27°C）的长日照（16:8光:暗）或短日照（8:16光:暗）光周期条件下4周，通过人工照明提供延长的光照。光周期对体重或卡路里消耗没有影响。然而，饲养在长光周期且有延长人工光照的小鼠选择性地发展出更大的内脏WAT质量，而皮下WAT或肩胛间棕色脂肪组织（BAT）质量没有变化。这伴随着内脏WAT中 和 mRNA表达的降低，而 、 或 没有变化。当与昼夜节律时间对齐但与黑暗开始时间无关时，内脏WAT中 、 和 mRNA的表达在长光周期和短光周期之间随时间不同，表明时钟基因表达随光周期发生改变。这些发现表明，通过人工光延长光周期可单独促进内脏脂肪积累，独立于温度，支持人工光可能在肥胖中起作用。
