寒冷刺激诱导大鼠棕色脂肪组织中的心脏干细胞增多

目的:检测寒冷刺激下大鼠肩胛部棕色脂肪组织中的心脏干细胞.方法:将大鼠随机分为2组,每组6只.实验组在寒冷环境下(4℃)饲养,对照组在常温条件(24℃)饲养.4周后分离肩胛部棕色脂肪比较两组脂肪组织活性.运用联合酶消化法提取并体外培养棕色脂肪来源细胞,使用流式方法检测相应细胞表面标记物的表达情况,体外培养4周后运用免疫...     

3,5-二碘-L-甲状腺素对白色脂肪棕色化的作用

目的 探究3,5-二碘-L-甲状腺素(T2)诱导白色脂肪棕色化的作用.方法 3T3-LI脂肪前体细胞诱导分化并用油红O染色进行鉴定;细胞分化过程中予不同浓度梯度(1 nmol/L、10 nmol/L、100 nmol/L)的T2处理,待细胞分化成熟后,分别用实时荧光定量PCR、Western印迹检测解耦联蛋白-1(UCP-1)表达水平的变化;仅予高浓度(100 nmol/L) T2处理,Western印迹法检测其他棕色脂肪功能性基因,包括诱导细胞死亡DNA片段化因子α样效应因子A(CIDEA)、过氧化物酶体增殖物活化受体γ协同刺激因子-1α(PGC-1α)蛋白表达变化.结果 3T3-L1脂肪前体细胞呈成纤维细胞样形态,胞浆中无脂滴;诱导分化成熟后光镜下油红O染色可见细胞内大量环状脂滴.在细胞分化过程中予不同浓度T2干预后,分化成熟的脂肪细胞上UCP-1 mRNA水平均有升高(t=3.97、11.77、17.7,P均＜0.05),蛋白表达水平也均有改变(t=13.31、14.55、23.62,P均＜0.05),且在高浓度(100nmoL/L)下最明显.在高浓度T2(100 nmol/L)干预下,成熟脂肪细胞的棕色脂肪其他功能性基因蛋白CIDEA、PGC-1α水平表达增加(t=15.92、17.36,P均＜0.05).结论 T2可诱导由3T3-L1脂肪前体细胞分化而来的成熟白色脂肪细胞表达棕色脂肪功能性基因.     

白色脂肪棕色化及其调控因素

近年,对脂肪组织的起源、分化、作用及调节的认识有了新的进展.体内的白色脂肪组织负责储存能量并分泌一些脂肪因子参与各种代谢性疾病的发生,而棕色脂肪组织主要负责产热和消耗能量.因此,“白色脂肪棕色化”对肥胖及许多相关疾病有着巨大的治疗潜力,可为这些疾病的治疗提供新的选择.“白色脂肪棕色化”这一过程受多种因素调控,如多种转录调节剂、蛋白质和激素等,因此未来可通过干预这些调控因素来研究相关疾病的新治疗方法.     

过氧化物酶体增殖物激活受体γ激动剂对肥胖小鼠非肾上腺素能原代棕色脂肪功能和分化的影响

目的探索过氧化物酶体增殖物激活受体γ（PPAR-γ）激动剂吡格列酮（PGZ）对肥胖小鼠非肾上腺素能条件下原代棕色脂肪分化和功能的影响,为2型糖尿病和肥胖的治疗提供新依据。方法高脂饮食诱导的4周龄雄性C57BL／6J肥胖小鼠20只,取肩胛间区棕色脂肪组织,分离并培养C57小鼠原代棕色脂肪细胞,等量分人10个培养皿中,等分为对照组和PGZ干预组,每组5皿,使用PGZ干预细胞,建立PGZ干预的细胞模型,使用和PGZ溶液等量的生理盐水处理对照组细胞。实时定量聚合酶链反应（RT-PCR）检测细胞模型的棕色脂肪基因：解偶联蛋白1（UCP-J）、超长链脂肪酸延长酶3（ELOVL3）、PPAR-γ共激活因子α和β（PGCI-α、PGCI-β）、PR包含域16区（PRDM16）、CCAAT增强子结合蛋白β（CEBP/β）、脂联素、脂肪细胞脂质结合蛋白2（AP2）、细胞色素C1氧化酶（CYC1）、线粒体转录因子A（TFAM）等表达水平;使用油红染色定量法检测细胞模型的棕色脂肪成脂功能;Western blotting法检测PGZ干预组UCP-1蛋白表达。2组间比较采用t检验,多组间比较采用方差分析和LSD检验。结果PGZ干预组细胞的棕色脂肪特异基因（UCP-1、ELOVL3、PGCI-α、PGCI-β）、成脂基因（AP2）、线粒体功能基因（CYCI、TFAM）和脂肪分化基因（PRDM16、CESP／β）表达量均显著高于对照组（相对表达量分别为：UCP-1：1100．0±612．0、2．0±0．4;ELOVL3：1461．0±617．0、2．0±1．2;PGCI-α：8．1±2．8、2．0±1．1;PGCI-β：8．3±2．8、2．0±1．3;脂联素：2．6±0．8、1．04±0．7;AP2：5．1±2．2、1．00±0．24;CYCI：3．1±0．8、1．0±0．4;TFAM：1．2±0．4、1．00±0．25;PRDM16：4．8±2．6、2．0±0．3;CEBP／β：6×10^8±5×10^8、2．0±0．6;t=2．45～5．22,均P〈0．05）;油红定量亦发现干预组成脂功能高于对照组（染色定量：1．2±0．2比1．0±0．1,t=2．45,P〈0．05）。Westernblotting检测PGZ干预组UCP-1表达高于对照组（灰度分析相对定量分别为1．24±0．25和1．00±0．14,t=2．63,P〈0．05）。结论PGZ可能通过增强棕色脂肪特异基因表达、促进细胞分化成脂、提高线粒体功能等方面增强棕色脂肪细胞功能,这可能是其改善机体代谢的原因之一。     

糖皮质激素对高脂饮食肥胖大鼠棕色脂肪和骨骼肌PGC-1αmRNA表达的影响

实时荧光定量PCR方法检测大鼠棕色脂肪和骨骼肌中PPARγ辅激活因子1α(PGC-1α)mRNA的表达.肥胖大鼠棕色脂肪和骨骼肌中PGC-1α mRNA表达水平低于普通大鼠(均P<0.01);应用高剂量糖皮质激素后普通大鼠和肥胖大鼠棕色脂肪和骨骼肌中PGC-1α mRNA表达水平降低.     

白色脂肪棕色化研究进展

以往的观点认为,哺乳动物体内主要存在两种脂肪组织——白色脂肪（WAT）和棕色脂肪（BAT）。WAT的主要功能是以甘油三酯的形式储存能量,而BAT则通过产热来维持机体的能量代谢平衡。近年来,人们在WAT中发现了一种与BAT一样具有产热功能的所谓“米色脂肪”（beigecell）,这种现象也被认为是WAT棕色化。     

棕色脂肪组织移植减肥和改善糖脂代谢的研究进展

棕色脂肪组织（BAT）是人体非颤栗性产热的主要场所。多项研究证明,移植BAT具有减轻体重、改善糖代谢、逆转1型糖尿病等重要作用,作用机制包括激活内源性BAT、促进产热相关基因的表达、增加机体能量消耗、通过分泌棕色脂肪细胞因子改善糖脂代谢、减轻脂肪组织炎症。BAT在能量调节和全身代谢中发挥的作用为减肥及改善糖脂代谢异常提...     

转录调控脂肪形成——代谢性疾病的新一代治疗

2012年第72届美国糖尿病协会(ADA)年会上,Bruce Soiegelman教授获得Banting科学成就奖.会上Soiegelman作了题为“转录调控脂肪形成——代谢性疾病的新一代治疗”的演讲.他报道了一种新发现的糖代谢关键调节激素——虹神素(Irisin)和第三类型脂肪——米色脂肪组织的脂肪细胞.其研究工作包括:(1 )PR域包含蛋白16(PRDM16)是控制棕色脂肪组织与骨骼肌组织相互转换的开关.(2) PRDM16决定小鼠皮下白色脂肪组织的产热方式.(3)米色脂肪细胞是小鼠和人类一种独特的产热脂肪细胞.(4)米色脂肪组织可用于减肥.(5)过氧化物酶体增殖物活化受体(PPAR)-γ协同刺激因子(PGC)-1α依赖的白色脂肪棕色样改变及产热作用与Irisin有关.     

产热型脂肪分化调控机制研究进展

脂肪组织是调节人体能量代谢的重要器官。储能型脂肪（白色脂肪）过量积累可导致肥胖,引发健康问题,而产热型脂肪（棕色/米色脂肪）通过线粒体的氧化产热消耗能量,具有潜在的抗肥胖作用。研究显示产热型脂肪可由众多前体细胞分化而来,其分化方向受多种转录因子包括PRDM16、PPARγ、SIRT1等调控,且这些转录因子参与了动脉粥样硬化的发生。本文就调控产热型脂肪分化形成的分子机制综述如下。     

吡格列酮对肥胖小鼠原代棕色脂肪细胞分化和功能基因表达的影响

观察吡格列酮对肥胖小鼠原代棕色脂肪(brown adipose tissue,BAT)细胞分化和功能基因表达的影响,并为治疗肥胖相关疾病寻找新思路.结果显示吡格列酮通过增强特异基因表达、促进分化成脂、提高线粒体功能等方面增强BAT细胞功能(P＜0.05);这可能是吡格列酮改善机体代谢的重要原因.     

Stearic acid content of abdominal adipose tissues in obese women

Objective:

Subcutaneous (SC) adipose tissue stearic acid (18:0) content and stearoyl-CoA desaturase-1 (SCD1)-mediated production of oleic acid (18:1) have been suggested to be altered in obesity. The objective of our study was to examine abdominal adipose tissue fatty acid content and SCD1 mRNA/protein level in women.

Subjects and methods:

Fatty acid content was determined by capillary gas chromatography in SC and omental (OM) fat tissues from two subgroups of 10 women with either small or large OM adipocytes. Samples from 10 additional women were used to measure SCD1 mRNA and protein expression, total extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphorylated ERK1/2 protein as well as insulin receptor (IR) expression levels.

Results:

OM fat 18:0 content was significantly lower in women with large OM adipocytes compared with women who had similar adiposity, but small OM adipocytes (2.37±0.45 vs 2.75±0.30 mg per 100 g adipose tissue, respectively, P⩽0.05). OM fat 18:0 content was negatively related to the visceral adipose tissue area (r=−0.44, P=0.05) and serum triglyceride levels (r=−0.56, P<0.05), while SC fat 18:0 content was negatively correlated with total body fat mass (BFM) (r=−0.48, P<0.05) and fasting insulin concentration (r=−0.73, P<0.005). SC adipose tissue desaturation index (18:1/18:0), SCD1 expression and protein levels were positively correlated with BFM. Moreover, obese women were characterized by a reduced OM/SC ratio of SCD1 mRNA and protein levels. A similar pattern was observed for ERK1/2 and IR expression.

Conclusion:

The presence of large adipocytes and increased adipose mass in a given fat compartment is related to reduced 18:0 content and increased desaturation index in women, independently of dietary fat intake. The depot-specific difference in ERK1/2 expression and activation, as well as in SCD1 and IR expression in obese women is consistent with the hypothesis that they may predominantly develop SC fat, which could in turn help protect from metabolic disorders.     

Factors involved in white‐to‐brown adipose tissue conversion and in thermogenesis: a review

Obesity is the result of energy intake chronically exceeding energy expenditure. Classical treatments against obesity do not provide a satisfactory long‐term outcome for the majority of patients. After the demonstration of functional brown adipose tissue in human adults, great effort is being devoted to develop therapies based on the adipose tissue itself, through the conversion of fat‐accumulating white adipose tissue into energy‐dissipating brown adipose tissue. Anti‐obesity treatments that exploit endogenous, pharmacological and nutritional factors to drive such conversion are especially in demand. In the present review, we summarize the current knowledge about the various molecules that can be applied in promoting white‐to‐brown adipose tissue conversion and energy expenditure and the cellular mechanisms involved.     

Visceral/epicardial adiposity in nonobese and apparently healthy young adults: Association with the cardiometabolic profile

Objective

We investigate associations of regional adipose tissues with cardiometabolic profile of nonobese and apparently healthy young adults.

Methods

Four hundred twenty-five nonobese and apparently healthy individuals were assessed for blood pressure and fasting lipid profile, blood glucose and adiponectin. Subcutaneous abdominal adipose tissue (SAT) and ectopic fat depots (visceral abdominal adipose tissue [VAT], epicardial adipose tissue [EAT] and hepatic fat fraction [HFF]) were quantified by magnetic resonance imaging.

Results

According to anthropometric measurements, blood pressure and blood markers, the population (18–35 years, 54% women) had a low cardiometabolic risk. Compared to women, men had more VAT, EAT and HFF, but less SAT. Regional adipose tissues were positively correlated with each other. VAT and EAT carried significant correlations with all markers of cardiometabolic risk, while SAT and HFF correlated variably with these markers. While taking into account age and gender, SAT, VAT and EAT were associated with most cardiometabolic markers, while HFF was only associated with total cholesterol/high-density lipoprotein ratio (TC/HDL-C) and triglycerides (TG). When comparing SAT, VAT and EAT head-to-head, VAT was the only adipose tissue location maintaining significant association with most markers of cardiometabolic risk. Greater VAT (≥50th percentile) was associated with a worse cardiometabolic profile, whether individuals were overweight or normal weight.

Conclusion

Even in nonobese and apparently healthy young women and men, accumulation of ectopic visceral adiposity in general, and of VAT in particular, is associated with a worse cardiometabolic profile whether individuals were overweight or normal weight.     

Targeting epicardial adipose tissue with exercise,diet, bariatric surgery or pharmaceutical interventions: A systematic review and meta‐analysis

Epicardial adipose tissue (EAT) and pericardial adipose tissue (PAT) are metabolically active fat depots implicated in cardiovascular disease, and EAT has potential as a novel cardiac risk factor, suitable as a target for interventions. The objective of this systematic review and meta‐analysis was to investigate the evidence whether EAT and PAT volume can be reduced by weight‐loss interventions (exercise, diet, bariatric surgery or pharmaceutical interventions). A systematic literature search identified 34 studies that were included in the qualitative synthesis (exercise, n = 10, diet, n = 5, bariatric surgery, n = 9 and pharmaceutical interventions, n = 10). Of the 34 studies, 10 reported sufficient data to be included in the meta‐analysis. The meta‐analysis was only conducted for changes in EAT volume, since only few controlled studies reported changes in PAT (n = 3) or total cardiac adipose tissue volume (n = 1). A significant pooled effect size (ES) for reduction in EAT volume was observed following weight‐loss interventions as compared with control interventions (ES = ?0.89, 95% CI: ?1.23 to ?0.55, P < 0.001). When comparing the effect of exercise training versus control on EAT volume reduction, there was a significant pooled ES favouring exercise training (ES: ?1.11, 95% CI: ?1.57 to ?0.65, P < 0.001). Similarly, the ES of pharmaceutical versus control interventions on EAT volume reduction was significant, favouring pharmaceutical interventions (ES: ?0.79, 95% CI: ?1.37 to ?0.21, P < 0.0072). In conclusion, this systematic review and meta‐analysis provides evidence that exercise, diet, bariatric surgery and pharmaceutical interventions can reduce cardiac adipose tissue volume.