一种新型脂肪细胞:beige细胞

最近的研究发现,与传统的白色和棕色脂肪细胞不同,脂肪组织中还存在另外一种新型的脂肪细胞,它们散在分布于白色脂肪组织中,受寒冷刺激或β3肾上腺素能受体激动剂激活后,表现出棕色脂肪细胞的特点,棕色脂肪细胞特异的解耦联蛋白1(UCP1)等基因的表达显著增高,产热和能量消耗能力增强.这一过程被称为“白色脂肪细胞棕色化”,这些细胞被命名为brite(brown to white)细胞或者beige(the intermediate color between white and brown)细胞.由于beige细胞在机体内分布广泛,并具有显著的消耗能量的功能,因此可能成为未来减肥药物开发的靶点.     

解偶联蛋白与心肌能量代谢研究进展

<正> 解偶联蛋白(unoupling proteins,UCP)是存在于细胞线粒体内膜上的蛋白质,占整个线粒体蛋白6%～8%,它能降低线粒体内膜电化学梯度从而减少能量生成,同时释放热量。目前已发现了5类:UCP1～5,这5类UCP在结构和功能上相似,因分布不同,它们的生理作用有所不同,在心血管系统中主要表达的是UCP2、UCP3,现就UCP2、UCP3的结构与功能、主要生理作用及其在心血管疾病中的研究进展作一综述。1 UCP的结构分布1.1 UCP2 UCP2的基因位于大鼠的7号染色体和人的11号染色体11q1 3,长6.5 kb,相对分子质量为33.218,含6     

生长分化因子11在白色脂肪细胞棕色化中的作用研究

目的 探讨生长分化因子11（GDF11）在白色脂肪细胞棕色化中的作用。方法 由C3H10T1/2细胞诱导分化而来的成熟白色脂肪细胞随机分为正常对照组，GDF11组；Western blot检测GDF11孵育成熟白色脂肪细胞后UCP1蛋白的表达；实时PCR检测GDF11对棕色脂肪标志基因表达的影响。结果 分别加入浓度为25 ng/ml、50 ng/ml、100 ng/ml 的GDF11，与正常对照组相比加入100 ng/ml的GDF11能够明显促进UCP1的表达（P<0.05），而25 ng/ml和50 ng/ml的GDF11可以在一定程度上诱导UCP1的表达却无显著统计学差异；同时，100 ng/ml的GDF11能够促进棕色脂肪标志基因ucp1、cidea、cox7α、dio2和elovl3的表达（P<0.05）和线粒体DNA拷贝数的增加（P<0.05）。结论 GDF11可显著促进白色脂肪细胞向棕色脂肪细胞转化。     

GIRK4在肥胖大鼠脂肪组织中的表达

目的 研究饮食诱导肥胖大鼠G蛋白耦联(门控)内向整流钾离子通道(GIRK4)基因在脂肪组织中的表达,探讨其与肥胖的相关性.方法 30只Sprague-Dawley大鼠随机分为两组:对照组(n=10),予以普通饲料饲喂;肥胖组(n=20),予以高脂肪、高热量饮食饲喂.8周后处死大鼠,提取两组的白色脂肪组织和棕色脂肪组织,...     

自噬核心蛋白Atg101对脂肪细胞衰老的影响

目的初步探究自噬核心蛋白Atg101对白色脂肪细胞衰老的影响。方法构建Atg101敲减的3T3-L1成熟脂肪细胞模型, 验证Atg101对自噬相关蛋白LC3和p62蛋白的影响。构建并分析人类皮下脂肪组织的RNA-seq数据库, 基于Atg101与其他基因FPKM值的Pearson相关系数(R2>0.4,P<0.050)预测共表达基因集并进行KEGG和Reactome富集分析。构建年轻小鼠(8周龄)和老龄小鼠(18个月龄)模型, 实时定量PCR(RT-qPCR)和Western印迹法检测Atg101在腹股沟皮下脂肪和内脏脂肪中的表达水平。进一步通过RNA-seq、Western印迹和RT-qPCR检测白色脂肪细胞衰老相关分泌表型(senescence-associated secretory phenotype, SASP)、细胞周期及线粒体稳态相关基因的表达差异, 分析Atg101敲减对脂肪细胞衰老的影响。结果在3T3-L1脂肪细胞敲减Atg101后自噬相关蛋白LC3-Ⅱ显著降低, p62蛋白明显上调, 提示细胞自噬受损。KEGG富集分析发现Atg101共表达基因集主要富集...     

己酮可可碱对非酒精性脂肪肝大鼠肝组织线粒体解耦联蛋白表达的影响

目的 探讨己酮可可碱(PTX)对非酒精性脂肪肝性肝病(NAFLD)大鼠线粒体解耦联蛋白(UCP)-2 mRNA表达的影响. 方法 SD大鼠60只,正常喂养1周后随机分为3组,每组20只.其中对照组20只,以普通饲料喂养,实验组和干预组各20只,以高脂饲料喂养,干预组高脂饮食4周后,在饮水中加用已酮可可碱(PTX)(100 mg·Kg-1·d-1),于第24周处死,采用反转录聚合酶链反应(RT-PCR)技术检测肝脏UCP-2mRNA的表达. 结果 对照组大鼠肝脏UCP2mRNA呈微量表达(1.2±0.1),实验组大鼠肝脏UCP2mRNA呈强表达(4.0±0.3),干预组大鼠肝脏UCP2mRNA呈弱表达(3.0±0.2),3组间UCP-2mRNA表达差异有统计学意义(F=160.67,P＜0.01). 结论 己酮可可碱可下调NAFLD大鼠肝细胞UCP-2mRNA的表达.     

替米沙坦对胰岛素抵抗SD大鼠内脏脂肪细胞体积的影响

目的观察替米沙坦对长期高糖高脂(HSHF)膳食喂养诱导的胰岛素抵抗SD大鼠内脏脂肪细胞体积的影响,探讨其对大鼠胰岛素抵抗程度影响的机制。方法将雄性SD大鼠随机分为3组:正常对照组(对照组,n=10)、高糖高脂组(HSHF组,n=10)、高糖高脂+替米沙坦组(替米沙坦组,n=10)。模型组给予高糖高脂膳食喂养24周后,对照组和HSHF组继续同前喂养12周,替米沙坦组给予替米沙坦干预12周。试验结束后测定各组大鼠体重、空腹血糖(FPG)、空腹胰岛素(FINS)和三酰甘油(TG),计算胰岛素抵抗指数(HOMA IR);同时留取各组大鼠左侧附睾脂肪组织HE染色光镜下观察脂肪细胞体积。结果与正常对照组大鼠相比,HSHF组大鼠体重、FPG、FINS、TG、HOMA-IR升高,差异有统计学意义(P0.05);与HSHF组大鼠相比,替米沙坦组体重、TG、FINS、HOMA IR水平均显著降低,差异有统计学意义(P0.05)。HE染色镜下观察:正常对照组可见脂肪细胞大小均一,体积小;HSHF组可见脂肪细胞大小不均一,体积较大;相比于HSHF组,替米沙坦组脂肪细胞体积减小,大小均一性较好。结论替米沙坦能够减轻长期HSHF膳食喂养大鼠体重,改善其脂代谢,减轻胰岛素抵抗;替米沙坦可减小长期HSHF膳食喂养大鼠内脏脂肪细胞体积,从而改善胰岛素抵抗。     

肥胖治疗新希望：白色脂肪棕色化

哺乳动物体内有两种脂肪组织,白色脂肪和棕色脂肪。白色脂肪以储存能量为主,棕色脂肪则以消耗能量产热,维持体温恒定。棕色脂肪组织约占体重的2％以下,棕色脂肪细胞富含大量线粒体和解偶联蛋白1（UCP-1）,线粒体产生大量的ATP,通过UCP-1的解偶联作用,转换成热量释放。棕色脂肪细胞也有大量的脂滴,与白色脂肪细胞不同,它们以多房小脂滴形式存在,更方便于被氧化利用。     

omega-3多不饱和脂肪酸治疗非酒精性脂肪性肝病的研究进展

随着人们生活方式和饮食结构的改变,非酒精性脂肪性肝病(NAFLD)发病率逐年上升,严重威胁人类健康。NAFLD疗法一直是基础和临床肝病研究的热门领域。近年来,诸多研究揭示omega-3多不饱和脂肪酸(ω3-PUFA)可促进脂肪酸氧化并改善肠道稳态,从而改善脂代谢和肝脏炎症,因而越来越多的临床研究开始将ω3-PUFA运用于NAFLD的治疗中。然而,ω3-PUFA治疗NAFLD的机制尚不明确,相关临床研究也存在一定局限性。主要介绍了ω3-PUFA在NAFLD中发挥的作用以及相关的临床研究结果,并进一步讨论ω3-PUFA治疗NAFLD尚需解决的问题。     

心力衰竭大鼠解偶联蛋白2表达及其对线粒体功能的影响

目的观察心力衰竭大鼠心肌线粒体解偶联蛋白2(uncoupling protein 2,UCP2)表达及其对线粒体功能的影响。方法45只雄性SD大鼠随机分为腹主动脉缩窄组(实验组)、假手术组和正常对照组,实验组行腹主动脉缩窄术。术后20周心脏超声检测心功能,测定血清游离脂肪酸(free fatty acid,FFA)浓度,免疫印迹法分析心肌线粒体UCP2蛋白表达,密度梯度法提取大鼠心肌线粒体,氧电极法测定线粒体的呼吸活性,罗丹明123法测定线粒体膜电位。结果实验组术后20周左心室射血分数比假手术组和正常对照组降低[(41.0±6.7)%vs.(84.0±2.5)%,P<0.01;(41.0±6.7)%vs.(84.0±2.3)%,P<0.01]、舒张末期内径比假手术组和正常对照组增加[(6.80±0.58)mm vs.(5.20±0.78)mm,P<0.01;(6.80±0.58)mm vs.(5.00±0.67)mm,P<0.01],大鼠心力衰竭建模成功。与正常对照组和假手术组比较,实验组血清FFA浓度明显增高[(372±14)μmol/L vs.(218±16)μmol l/L,P<0.01;(372±14...     

The effects of dietary fatty acid composition in the post-sucking period on metabolic alterations in adulthood: can ω3 polyunsaturated fatty acids prevent adverse programming outcomes?

Early life nutrition is important in the regulation of metabolism in adulthood. We studied the effects of different fatty acid composition diets on adiposity measures, glucose tolerance, and peripheral glucocorticoid (GC) metabolism in overfed neonatal rats. Rat litters were adjusted to a litter size of three (small litters (SLs)) or ten (normal litters (NLs)) on postnatal day 3 to induce overfeeding or normal feeding respectively. After weaning, SL and NL rats were fed a ω6 polyunsaturated fatty acid (PUFA) diet (14% calories as fat, soybean oil) or high-saturated fatty acid (high-fat; 31% calories as fat, lard) diet until postnatal week 16 respectively. SL rats were also divided into the third group fed a ω3 PUFA diet (14% calories as fat, fish oil). A high-fat diet induced earlier and/or more pronounced weight gain, hyperphagia, glucose intolerance, and hyperlipidemia in SL rats compared with NL rats. In addition, a high-fat diet increased 11β-hsd1 (Hsd11b1) mRNA expression and activity in the retroperitoneal adipose tissue of both litter groups compared with standard chow counterparts, whereas high-fat feeding increased hepatic 11β-hsd1 mRNA expression and activity only in SL rats. SL and a high-fat diet exhibited significant interactions in both retroperitoneal adipose tissue and hepatic 11β-HSD1 activity. Dietary ω3 PUFA offered protection against glucose intolerance and elevated GC exposure in the retroperitoneal adipose tissue and liver of SL rats. Taken together, the results suggest that dietary fatty acid composition in the post-sucking period may interact with neonatal feeding and codetermine metabolic alterations in adulthood.     

Low expression of insulin signaling molecules impairs glucose uptake in adipocytes after early overnutrition

Experimental and clinical studies have demonstrated that early postnatal overnutrition represents a risk factor for later obesity and associated metabolic and cardiovascular disturbance. In the present study, we assessed the levels of glucose transporter 4 (GLUT-4), GLUT-1, insulin receptor (IR), IR substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K) and Akt expression, as well as insulin-stimulated glucose transport and Akt activity in adipocytes from adult rats previously raised in small litters (SL). The normal litter (NL) served as control group. We also investigated glycemia, insulinemia, plasma lipid levels, and glucose tolerance. Our data demonstrated that early postnatal overfeeding induced a persistent hyperphagia accompanied by a significant increase in body weight until 90 days of age. The SL group also presented a significant increase ( approximately 42%) in epidydimal fat weight. Blood glucose, plasma insulin, and lipid levels were similar among the animals from the SL and NL groups. While insulin-stimulated glucose uptake was approximately twofold higher in adipocytes from the NL group, no stimulatory effect was observed in the SL group. The impaired insulin-stimulated glucose transport in adipose cells from the SL rats was associated with a significant decrease in GLUT-4, IRS-1 and PI3K expression, and Akt activity. In contrast, IR and Akt expression in adipocytes was not different between the SL and NL groups. Despite these alterations, our results showed no differences in glucose tolerance test in rats raised under different feeding conditions. Our findings reinforce a potent and long-term effect of neonatal overfeeding, which can program major changes in the metabolic regulatory mechanisms.     

The effect of leptin treatment on the development of obesity in overfed suckling Wistar rats

OBJECTIVE: To identify the role of hyperleptinaemia in mediating the effects of early postnatal overfeeding in a rat strain known to be prone to manipulations of the early environment which result in predispositions for obesity and associated metabolic and cardiovascular disturbance in later life. DESIGN: Wistar rats were reared in normal litters (NL, 10--12 pups) or small litters (SL, four pups) from postnatal day 3 and killed for determination of body composition and plasma leptin and insulin concentrations on day 7 or day 21 after having been treated with recombinant leptin (2 x 50 (pmol/g)/day) or saline from day 1. RESULTS: Rearing in SL doubled the body fat content and plasma leptin levels in comparison to NL pups by 21 days of age. Under leptin-treatment throughout suckling age, NL pups remained leptin responsive, ie the difference in body fat content was progressively reduced relative to the controls. Until 7 days of age, despite the body fat content of untreated SL pups being 2-fold higher and their plasma leptin level 7-fold higher than that of NL pups, leptin treatment caused the same percentage decreases in body fat in SL than in NL pups. But in contrast to NL pups, the SL pups became leptin resistant thereafter. Plasma insulin levels in 7-day-old leptin-treated SL pups were 3-fold higher than in untreated littermates and 5-fold higher than in the NL groups. CONCLUSION: Prophylactic leptin treatment does not prevent hyperinsulinaemia and excessive fat deposition in SL pups. On the other hand, selective hyperleptinaemia during suckling age does not trigger leptin resistance and obesity in NL pups. Rather than hyperleptinaemia per se, other factors associated with early postnatal overnutrition, for example, the concurrent hyperinsulinaemia, seem to play a pivotal role for the development of leptin-resistance and life-long obesity risk in SL rats.     

The effect of maternal prolactin infusion during pregnancy on fetal adipose tissue development

The present study determines whether maternal administration of prolactin (PRL) to dams promotes the abundance of the brown adipose tissue-specific uncoupling protein-1 (UCP1) in fetal and neonatal rat pups. Recombinant PRL (24 micro g/kg per day), or an equivalent volume of saline, were infused into dams (n=19 per group) throughout pregnancy from 12 h after mating. Interscapular brown adipose tissue was sampled either from fetuses at 19.5 days of gestation (term=21.5 days) or from neonatal rat pups at approximately 18 h after birth. The abundance of UCP1 was determined by immunoblotting on adipose tissue samples from individual pups and pooled from groups of pups. This analysis was complemented by immunocytochemistry on representative adipose tissue samples. Maternal PRL infusion resulted in a greater abundance of UCP1 in fetal rats at 19.5 days of gestation (control: 97.2+/-8.4% reference; PRL: 525.6+/-74.4% reference; P<0.001) and in neonates 18 h after birth. In contrast, the abundance of the outer mitochondrial membrane protein voltage-dependent anion channel was unaffected by PRL. Neonatal adipose tissue sampled from pups born to PRL-infused dams possessed fewer lipid droplets, but more UCP1, as determined by immunocytochemistry. Fetal, but not maternal, plasma leptin concentrations were also increased by maternal PRL administration. In conclusion, as rats are altricial, and the potential thermogenic activity of brown adipose tissue develops over the first few days of postnatal life, these changes prior to, and at the time of, birth implicate PRL in fetal and neonatal adipose tissue maturation.     

Muscle endothelial-dependent microvascular dysfunction in adulthood due to early postnatal overnutrition

The aims of our study were to investigate effects of postnatal overnutrition, obtained by restricting the number of pups per litter, on microcirculatory reactivity, fat depots, its total percentage and lipid profile. Microvascular reactivity was evaluated in the cremaster muscle of 24 hamsters divided into four groups, with 6 animals in each one: normal (NL) and restricted (RL) litter groups, both at 6th and 21st weeks of age. The NL group had 8-9 pups and the RL 3 pups per litter and to avoid the litter effect, only one animal was used per litter. The results have shown that the RL group had higher velocity of weight, body mass and fat gain compared to the NL one at weeks 6 and 21. Significant differences were also observed on urogenital fat depot, total cholesterol and low density lipoprotein between groups. At the lowest concentration of Ach, the RL group showed smaller arteriolar dilatation at the 21st than at the 6th week [5(3-13) vs 19(8-40)%, p<0.01] while the NL one did not show any difference within the group. The highest concentration of Ach at the 21th week pointed to endothelial-dependent microvascular dysfunction in RL compared to NL [3(8-26) vs. 13(8-26)%, p<0.05]. Endothelial-independent microvascular reactivity was similar between groups. Our data suggest that postnatal overnutrition is associated to muscle endothelial-dependent microvascular dysfunction, greater body mass and total percentage of fat and impaired the lipid profile. In conclusion, the imprinting promoted by this experimental model of obesity was able to influence microvascular reactivity later in life.     

Prolactin, the prolactin receptor and uncoupling protein abundance and function in adipose tissue during development in young sheep

A primary role of the prolactin receptor (PRLR) during fetal and postnatal development has been suggested to be the regulation of uncoupling protein (UCP) expression. We, therefore, determined whether: (1) the rate of loss of UCP1 from brown adipose tissue after birth was paralleled by the disappearance of PRLR; and (2) administration of either pituitary extract prolactin (PRL) containing a mixture of posttranslationally modified forms or its pseudophosphorylated form (S179D PRL) improved thermoregulation and UCP1 function over the first week of neonatal life. PRLR abundance was greatest in adipose tissue 6 h after birth before declining up to 30 days of age, a trend mirrored by first a gain and then a loss of UCP1. In contrast, in the liver--which does not possess UCPs--a postnatal decline in PRLR was not observed. Administration of PRL resulted in an acute increase in colonic temperature in conjunction with increased plasma concentrations of non-esterified fatty acids and, as a result, the normal postnatal decline in body temperature was delayed. S179D PRL at lower concentrations resulted in a transient rise in colonic temperature at both 2 and 6 days of age. In conclusion, we have demonstrated a close relationship between the ontogeny of UCP1 and the PRLR. Exogenous PRL administration elicits a thermogenic effect suggesting an important role for the PRLR in regulating UCP1 function.     

Effects of intravenously infused leptin on insulin sensitivity and on the expression of uncoupling proteins in brown adipose tissue.

Centrally administered leptin has been shown to increase insulin-stimulated glucose utilization and to favor the expression of uncoupling proteins (UCPs). To study if leptin also has direct peripherally mediated effects on these processes, this hormone (1 mg/day) or its vehicle was infused i.v. for 4 days to lean rats and insulin-stimulated glucose utilization in skeletal muscle and adipose tissue as well as the expression of UCP messenger RNAs (mRNAs) in brown adipose tissue were measured. I.v. leptin administration resulted in decreases in food intake (31%), body weight gain, and plasma insulin levels (45%), in increases in overall (23%) as well as brown adipose tissue and muscle glucose utilization, and in decreases in white adipose tissue glucose uptake. Most of these changes were mimicked, in control rats, by giving them the same amount of food as that consumed by the leptin-infused group (pair-feeding). I.v. leptin infusion also favored the expression of UCPs in brown adipose tissue, either by increasing their expression or preventing the fall occurring during the pair-feeding regimen. Relative UCP expression levels were 100, 104, and 33 for UCP1, 100, 191, and 125 for UCP2 and 100, 107, and 29 for UCP3 in ad libitum fed control rats, in leptin-treated rats and in pair-fed control rats, respectively. These results suggest that the overall effect of leptin on glucose utilization and on the expression of UCPs may be mediated through central mechanism.     

NO-1886 (ibrolipim), a lipoprotein lipase activator, increases the expression of uncoupling protein 3 in skeletal muscle and suppresses fat accumulation in high-fat diet-induced obesity in rats

Although the lipoprotein lipase (LPL) activator NO-1886 shows antiobesity effects in high-fat-induced obese animals, the mechanism remains unclear. To clarify the mechanism, we studied the effects of NO-1886 on the expression of uncoupling protein (UCP) 1, UCP2, and UCP3 in rats. NO-1886 was mixed with a high-fat chow to supply a dose of 100 mg/kg to 8-month-old male Sprague-Dawley rats. The animals were fed the high-fat chow for 8 weeks. At the end of the administration period, brown adipose tissue (BAT), mesenteric fat, and soleus muscle were collected and levels of UCP1, UCP2, and UCP3 messenger RNA (mRNA) were determined. NO-1886 suppressed the body weight increase seen in the high-fat control group after the 8-week administration (585 +/- 39 vs 657 +/- 66 g, P < .05). NO-1886 also suppressed fat accumulation in visceral (46.9 +/- 10.4 vs 73.7 +/- 14.5 g, P < .01) and subcutaneous (43.1 +/- 18.1 vs 68.9 +/- 18.8 g, P < .05) tissues and increased the levels of plasma total cholesterol and high-density lipoprotein cholesterol in comparison to the high-fat control group. In contrast, NO-1886 decreased the levels of plasma triglycerides, nonesterified free fatty acid, glucose, and insulin. NO-1886 increased LPL activity in soleus muscle (0.082 +/- 0.013 vs 0.061 +/- 0.016 mumol of free fatty acid per minute per gram of tissue, P < .05). NO-1886 increased the expression of UCP3 mRNA in soleus muscle 3.14-fold (P < .01) compared with the high-fat control group without affecting the levels of UCP3 in mesenteric adipose tissue and BAT. In addition, NO-1886 did not affect the expression of UCP1 and UCP2 in BAT, mesenteric adipose tissue, and soleus muscle. In conclusion, NO-1886 increased the expression of UCP3 mRNA and LPL activity only in skeletal muscle. Therefore, a possible mechanism for NO-1886's antiobesity effects in rats may be the enhancement of LPL activity in skeletal muscle and the accompanying increase in UCP3 expression.     

In vitro induction of UCP1 mRNA in preadipocytes from rabbit considered as a model of large mammals brown adipose tissue development: importance of PPARgamma agonists for cells isolated in the postnatal period

In mammals with a lower mass-specific metabolic rate than small laboratory rodents, the brown adipose tissue (BAT) loses its thermogenic activity after birth and undergoes a transformation into white adipose tissue (WAT). Rabbit is a model of these mammals of larger body mass. Preadipocytes from cervical BAT of foetal or newborn rabbits differentiated in a chemically-defined medium and expressed low levels of uncoupled protein-1 (UCP1) mRNA, greatly increased by beta3-adrenergic or retinoic acid stimulations. On the contrary, preadipocytes from 1-month-old animals differentiated in the same conditions with no detectable,expression of UCP1. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists were necessary to induce UCP1 in these cells from older animals, a synergistic increase being noted in the presence of beta3-adrenergic agonists. In contrast to these results, preadipocytes from perirenal WAT stimulated by PPARgamma agonists never expressed UCPI. CONCLUSION: preadipocytes in the postnatal period are determined as brown or white preadipocytes. PPARgamma agonists induce UCP1 expression in brown postnatal preadipocytes, but they are unable to trigger the gene in white preadipocytes.