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冷损伤在冬季户外作业人员中常见,长时间冷暴露会造成不可逆性损伤甚至危及生命。目前,对冷损伤的研究主要侧重在肢端损伤的对症治疗,尚缺乏针对体温和机体功能下降的干预策略。冷暴露过程中,核心体温下降是导致冷损伤最直接的因素。核心体温降至35 ℃时,则损伤开始[1]。核心温度为33~35 ℃则发生轻度低温,降至28~32 ℃为中度低温、17~27 ℃为深度低温。核心体温下降将引起重要器官、组织发生系列生理和病理变化,造成不同程度的损伤[2]。然而,目前维持核心体温的主要方式为穿戴保暖装备[3],有效维持核心体温的抗寒药物研究较少。因此,通过药物增加机体的产热作用,可能是预防冻伤的一种有效方法。
外界温度降低将导致基础产热无法维持体温恒定,继而发生颤抖性产热(shivering thermogenesis,ST)和非颤抖性产热(non-shivering thermogenesis,NST)[4]。与ST相比,NST可以持续产热且不会产生明显疲劳等不适感。棕色脂肪组织(brown adipose tissue,BAT)作为NST的最重要来源,在冷暴露中发挥着重要的调节产热能力[5]。当NST激活时,BAT线粒体内膜上的UCP1表达水平增多,线粒体中电子传递链断开ATP生成减少,使化学能转化为热能[6],从而增加机体产热、维持核心体温[7]。
米格列醇(miglitol)为第二代半合成α-糖苷酶抑制剂[8],结构与葡萄糖相似,通过延长餐后小肠中碳水化合物的吸收发挥降糖作用,为临床常用的口服抗糖尿病药物[9]。有证据表明,米格列醇有减脂作用[10, 11],这可能与其改变肠道中短链脂肪酸的生产有关[12]。近年研究表明,米格列醇具有独立于延缓碳水化合物吸收的减重机制[13]。米格列醇抑制脂质积累的机制可能是通过增加脂肪组织产热实现[14]。因此米格列醇对BAT的能量消耗水平、产热激活以及体温调节作用机制值得进一步探讨。
本研究以诱导分化成熟的棕色脂肪细胞和冷暴露小鼠为研究对象,探究米格列醇对棕色脂肪细胞增殖和脂质消耗的影响,考察冷暴露小鼠体温以及产热通路关键蛋白的变化,为深入探究米格列醇产热作用机制提供理论依据,为冷损伤提供干预策略。
Anti-frostbite effect of miglitol on cold-exposed mice through UCP1-mediated thermogenic activation
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摘要:
目的 探讨米格列醇调控棕色脂肪细胞能量代谢、改善冷暴露后小鼠寒冷损伤的作用及机制。 方法 将原代棕色脂肪细胞诱导成为成熟的脂肪细胞,通过MTT法考察米格列醇对棕色脂肪细胞活力的影响,采用油红O染色技术考察细胞给药后的脂滴消耗水平。在4 ℃、−20 ℃冷暴露过程中考察改善寒冷损伤的活性。将昆明小鼠随机分为空白对照组、冷暴露对照组、米格列醇组、全反式维甲酸组,重复给药 7 d后,应用红外热成像系统检测小鼠体表温度变化、肛温测定仪检测核心体温变化,通过足肿胀考察寒冷损伤水平,蛋白印迹法检测棕色脂肪中的产热关键蛋白解偶联蛋白1(uncoupling protein 1, UCP1)和过氧化物酶体增殖活化受体γ 辅助活化因子1α(peroxisome proliferator-activated receptor γ coactivator 1α, PGC1α)的水平。 结果 与空白对照组比较,米格列醇给药组的棕色脂肪细胞脂滴消耗水平显著增加。米格列醇给药组小鼠冷暴露后体表温度和核心温度水平显著增加,且小鼠棕色脂肪组织内的UCP1和PGC1α水平显著增高,表明米格列醇能够激活产热通路关键蛋白UCP1和PGC1α,增加小鼠在冷暴露后的产热能力,改善足趾肿胀的损伤作用。 结论 米格列醇可通过激活产热通路的关键靶点UCP1、PGC1α促进棕色脂肪产热而发挥改善冷暴露小鼠冷损伤的作用。 Abstract:Objective To investigate the effect and mechanism of miglitol on regulating the energy metabolism of brown adipocytes by activating UCP1 and improving cold injury in mice after cold exposure. Methods Primary brown adipocytes were induced into mature adipocytes, the effect of miglitol on the viability of brown adipocytes was investigated by MTT method, the lipid droplet consumption level of cells after drug administration was investigated by Oil Red O staining technology, and the level of UCP1, a key protein of thermogenesis in brown adipocytes, was detected by Western blotting. The activity of anti-frostbite was investigated in cold exposure at 4 ℃ and −20 ℃. KM mice, which were randomly divided into control group, cold exposure group, miglitol group and all-trans retinoic acid group, and after 7 days of repeated administration, the body surface temperature of mice was detected by infrared thermal imaging system, the anal temperature change was detected by anal thermometer, and the expression levels of UCP1 and PGC1-α in adipose tissue were detected by immunoblotting. Results Compared with the control group, the lipid droplet consumption and UCP1 expression levels in brown adipocytes in the miglitol group were significantly increased. The levels of body surface temperature and rectal temperature increased significantly after cold exposure, and the levels of UCP1 and PGC1α in the brown adipose tissue of mice increased significantly, which indicated that the miglitol could activate the critical proteins UCP1 and PGC1α of the thermogenesis pathway, increase the thermogenesis of mice after cold exposure, and thus improve the effect of cold injury for toe swelling. Conclusion Miglitol could play a role in improving cold injury and body temperature in mice by increasing the level of UCP1 and PGC1α, which are key targets of the thermogenesis pathway to promote the thermogenesis of brown fat. -
Key words:
- miglitol /
- brown adipose /
- thermogenesis /
- cold injury /
- UCP1
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