光污染或因改变棕色脂肪功能而导致肥胖

荷兰科学家发现如果将小鼠暴露在更长时间的光照下（模拟延长白天时间），动物的体脂会增加。长时间光照暴露并不导致动物进食量增多，也没有发现其运动量降低，出现代谢紊乱的原因是它们体内负责燃烧能量的棕色脂肪功能出现了问题。

这一研究团队将雄性小时暴露在12，16和24小时的光照条件下，历时5周后发现白天延长可以引起体脂增多，棕色脂肪从血浆中摄取脂肪酸和葡萄糖的能力下降。

在生物钟节奏和肥胖的关系上，体内棕色脂肪发挥了重要的介导作用。才研究表明棕色脂肪活性下降可能有助于解释为什么动物和人类生物钟节律被打乱后容易出现体重增加和代谢紊乱这一现象。难道都市光污染与肥胖大流行间当真有些许内在的关系？

http://www.pnas.org/content/early/2015/05/06/1504239112.abstract

Prolongeddaily light exposure increases body fat mass through attenuation of brownadipose tissue activity

Abstract

Disruptionof circadian rhythmicity is associated with obesity and related disorders,including type 2 diabetes and cardiovascular disease. Specifically, prolonged artificiallight exposure associates with obesity in humans, although the underlyingmechanism is unclear. Here, we report that increasing the daily hours of lightexposure increases body adiposity through attenuation of brown adipose tissue(BAT) activity, a major contributor of energy expenditure. Mice exposed to aprolonged day length of 16- and 24-h light, compared with regular 12-h light,showed increased adiposity without affecting food intake or locomotor activity.Mechanistically, we demonstrated that prolonged day length decreasessympathetic input into BAT and reduces β3-adrenergic intracellular signaling.Concomitantly, prolonging day length decreased the uptake of fatty acids fromtriglyceride-rich lipoproteins, as well as of glucose from plasma selectivelyby BAT. We conclude that impaired BAT activity is an important mediator in theassociation between disturbed circadian rhythm and adiposity, and anticipatethat activation of BAT may overcome the adverse metabolic consequences ofdisturbed circadian rhythmicity.

群晓科苑

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