高住低练对肥胖小鼠内源性大麻素系统的调节作用及其机制

The discovery of the endocannabinoid system (ECs), its role in the regulation of energy homeostasis and its control of appetite function, has received a great amount of attention recently. Our previous studies showed that after a weight loss program with diet and exercise, weight gain occurred often in young people. The relapse may be associated with appetite reinforcement after weight loss. However, our intervention with "living hypoxic-training normal" resulted in reduced appetite and less energy intake, which allowed for better maintained weight loss, compared to exercise alone. Thus, we hypothesize that the molecular and cellular mechanism underlying the better weight loss and longer maintenance induced by "living hypoxic-training normal" would be functional and regulatory changes of the ECs, specifically, that inhibiting the activation of CB1R receptors through metabolic hormones such as Leptin would lead to the attenuated cannabinoid inhibition in AMPKs pathway and in the meantime, PGC-1α and HIF-1α would activate the combination of cannabinoids with PPARs, consequently leading to the lessened appetite and facilitating lipolysis processes. The proposed study is, by using high-fat-diet induced obese mice from our previous studies as subjects, to determine the effects of a 4-wk "living hypoxic-training normal" intervention on the ECs activities of the hypothalamus and adipose tissue and on the regulatory changes of food intake and energy expenditure. The advanced techniques such as co-immunoprecipitation, Western blot, and HPLC will be applied to determine the effects; and the CB1R agonist and HIF-1α knockout are adopted to verify these mechanisms. The proposed research may advance the understanding of the mechanisms at molecular and cellular levels regarding the effects of "living hypoxic-training normal" on the ECs in the hypothalamus and adipose tissue. It may provide a theoretical basis for the effectiveness of "living hypoxic-training normal" as a "green" modality for better weight control, as well as for better prevention and possible treatment of some diseases such as obesity, fatty liver disease, and diabetes.

内源性大麻素系统（ECs）是近年来备受关注的既可有效调节食欲又可调控能量代谢的物质。我们前期研究发现运动结合饮食减体重后肥胖的反弹和食欲增强有关，而高住低练（人工低氧环境居住，平原环境运动）可有效抑制食欲，且比单独运动具有更佳的减重效果。我们推测高住低练减体重新机理：通过激素（如瘦素等）抑制大麻素受体（CB1R）活性，导致大麻素对AMPKs通路的抑制作用有所减弱；同时，通过PGC-1α和HIF-1α激活大麻素和PPARs结合，从而诱导食欲减退、脂肪分解代谢增强。本研究拟以我们前期的高脂饮食性肥胖小鼠模型为实验对象：通过应用免疫共沉淀、Western blot、高效液相等技术，观察4周高住低练对肥胖小鼠下丘脑和脂肪组织ECs以及摄食调控、能量代谢的影响，并使用CB1R激动剂、HIF-1α基因敲除进行验证。该研究为高住低练减体重的"绿色"方法提供理论基础，并为脂肪肝、糖尿病等的防治提供新思路。

内源性大麻素系统（Endocannabinoid system, ECS）在中枢能量摄入和外周糖脂代谢调控过程中发挥着重要作用。在肥胖形成过程中，以CB1受体为核心的ECS过度活化可促进中枢能量摄入，阻碍能量消耗，加速肥胖进程。. 健康饮食和加强运动是目前公认的最经济有效减重方式，但其存在的难题是：食欲增强。因此，寻找能防止食欲增强的有效减重方式，对长期体重管理具有重要意义。本课题组人体实验研究发现：对于肥胖青少年，高住低练比常氧训练减重效果更好，且重要的食欲、能量代谢调控因子和血清内源性大麻素水平显著下降。立足于人体实验研究结果，课题组首先系统研究了肥胖小鼠肥胖形成和平衡膳食减重过程中，机体重要的能量代谢器官ECS表达变化，得到平衡膳食减重后重要能量代谢器官ECS过度活化未得到改善的证据；其次，在验证高住低练减控体重效果的基础之上，观察高住低练对能量代谢器官ECS表达变化，得到相比平衡膳食减重，高住低练可更好改善能量代谢器官ECS表达变化的证据；并进一步分析以CB1受体为核心的ECS在高住低练调控肥胖小鼠糖脂代谢紊乱过程中的可能作用机制。.结果发现：（1）从超重向严重肥胖的形成过程中，肥胖小鼠血清大麻素含量呈上升趋势，脂肪组织大麻素合成酶与降解酶表达均下调，进而使脂肪组织ECS失衡；（2）平衡膳食干预减重效果显著，全脑和血清内源性大麻素均已恢复至正常水平，但肝脏和骨骼肌均存在未被逆转的ECS成分，其中以肝脏最为明显，其大麻素受体CB1和合成酶表达均处于较高水平；（3）高住低练减重效果明显，在下调肝脏、脂肪组织ECS成分表达的同时，显著改善了肥胖小鼠肝脏、骨骼肌和脂肪组织糖脂代谢紊乱现象；（4）高住低练改善肝脏脂代谢紊乱的部分可能机制为：下调肝脏CB1-SREBP-1/PPARγ通路，减少脂肪合成，从而改善脂代谢紊乱。. 本课题首次研究了肥胖形成和减重过程中ECS成分表达变化情况，有助于理解ECS在肥胖形成和减重过程中所扮演的角色；并首次发现了高住低练可能通过下调CB受体改善肥胖小鼠能量代谢器官糖脂代谢紊乱现象；高住低练可能通过CB1-SREBP-1/PPARγ通路，减少肝脏脂肪合成，改善肝脏脂代谢，为高住低练应用于长期体重管理提供了重要理论依据。