睡眠不足和夜间光暴露扰乱脂肪合成与分解代谢平衡促发肥胖

Obesity is the excessive accumulation and storage of fat in the body. Epidemiological studies have demonstrated that sleep insufficiency and night light exposure both can increase the risk of obesity, especially for children and adolescents, but the underlying mechanisms remain unclear. As a result, the current obesity prevention and control measures are still confined to diet and exercise, and the effectiveness were not satisfied, with obesity rates continuing to rise worldwidely, affecting countries rich and poor. This project is aimed to provide insights into the mechanisms for the obesity-promoting effects of sleep insufficiency and night light exposure, by investigating their influences on the balance between lipogenesis and lipolysis, based on animal experiments and combined with human trials. The central hypothesis is that sleep insufficiency and night light exposure may lead to increased adipogenesis and/or decreased lipolysis and fatty acid oxidation, which is prone to the occurrence and development of obesity, due to disruption of peripheral circadian clocks in adipose tissues and dysregulation of melatonin- and leptin-mediated lipid metabolic pathways. Western blot technique was mainly used to analyze the altered expression of clock and metabolic genes after intervention in C57BL/6J mice, including circadian genes BMAL1, PER2, RORα、β、ɤ, REV-ERBα、β, and HDAC3 in adipose tissues, key metabolic genes and other regulatory proteins involved in melatonin membrane receptors-, melatonin nuclear receptors- and leptin receptor-based lipid metabolic pathways, with special attention being paid to the joint effects of the two interference factors, the long-term effects, the effects of melatonin supplementation during intervention, the recovery effects after intervention, and the change of leptin sensitivity. This project is expected to provide primary in-vivo evidences that sleep insufficiency and night light exposure be obesity risk factors, and that new macro-measures, techniques and even molecular biological targets can be taken into consideration in obesity prevention and treatment.

肥胖实质是脂肪过量蓄积。睡眠不足和夜间光暴露皆能增加肥胖发生危险性，尤其对于儿童青少年的影响更甚，但其致病机理尚不明了，以至目前肥胖的群体防治措施仅局限于膳食和运动干预，防治效果不佳，肥胖发生率持续攀升。本项目以动物为实验对象，研究睡眠不足和夜间光暴露对脂肪合成与分解代谢平衡的影响。提出了睡眠不足和夜间光暴露可造成生物钟紊乱、褪黑素介导的脂代谢失调和瘦素抵抗，从而使机体脂肪生成大于分解产热的假说。研究主要采用Western blot等方法，探析睡眠剥夺和夜间光暴露对小鼠下丘脑与脂肪组织钟基因、肝脏褪黑素膜受体与核受体介导的脂代谢通路关键基因及调节因子、脑与脂肪组织瘦素信号通路及调节因子表达的影响，着重两因素的复合暴露效应、长期暴露效应、暴露期补充褪黑素效应、去暴露后的恢复效应等，旨在揭示睡眠不足和夜间光暴露扰乱脂代谢平衡促发肥胖的分子机制，为肥胖防治提供新的措施和分子靶点。

睡眠不足及夜间光暴露可能是肥胖的致病因素或危险因子，但其作用机制并不明了，以致针对此二因素的预防干预措施未得到应有重视。本项目采用动物实验法，通过建立小鼠睡眠剥夺和夜间光暴露模型，研究睡眠不足和夜间过度光暴露对机体脂肪合成与分解代谢平衡的影响及其分子机制，为肥胖防治提供新的实验依据。.利用睡眠剥夺仪的随机平移运动干扰法实施睡眠剥夺，使小鼠（C57BL/6J）每日睡眠时间不超过4小时。利用普通日光灯照明法进行夜间光暴露干预，使小鼠整夜暴露于日光灯照射下。实验分组主要包括短期（10天）睡眠剥夺或光暴露组、长期（90天）睡眠剥夺或光暴露组、短期睡眠剥夺或光暴露补充褪黑素组，等。重点针对“睡眠不足和夜间光暴露可能造成机体组织代谢生物钟紊乱、褪黑素介导的脂代谢失调和瘦素抵抗，从而使脂肪生成增加而分解产热减少”的研究假设，进行相关指标的测试验证。结果表明：.1)睡眠剥夺或夜间光暴露能够引起小鼠体重和体成分的改变，原因可能与睡眠剥夺或夜间光暴露导致褪黑素分泌抑制进而影响脂肪合成与分解代谢关键酶的表达水平，造成易于脂肪合成的总体变化有关。补充褪黑素可一定程度抵消睡眠剥夺或夜间光暴露对脂肪代谢关键酶（FAS、HSL、LPL等）基因表达的影响。.2)睡眠剥夺和夜间光暴露均会直接影响外周组织褪黑素受体介导的脂代谢调节通路关键信号分子。睡眠剥夺还对脂肪组织生物钟基因及下游钟控基因的表达具有显著影响，可能是其影响外周组织脂代谢的机制之一。.3)睡眠剥夺和夜间光暴露均可导致下丘脑瘦素信号通路关键分子POMC表达下调，而其竞争性抑制分子ROR表达上调，表明睡眠剥夺和夜间光暴露具有诱发中枢瘦素抵抗的潜在效应。.4)睡眠剥夺和夜间光暴露还会影响氨基酸代谢、核酸代谢及糖代谢等不同代谢通路，表明睡眠不足和夜间光暴露对机体代谢健康具有广泛的影响。.5）本研究结果支持睡眠不足和夜间光暴露是诱发肥胖的危险因子。通过合理保障睡眠和控制夜间光暴露，将会有利于预防肥胖和促进健康。