肥胖和肥胖抵抗大鼠脂肪组织PPARγ和aP2基因表达的研究

目的观察高脂饮食诱导的肥胖及肥胖抵抗大鼠脂肪组织中PPARγ和aP2 mRNA表达水平的变化。方法31只健康wistar雄性大鼠,随机选取7只作为对照组喂饲基础饲料,24只作为高脂组喂饲高脂饲料。第8周末按体重增量,从高脂组选出5只大鼠作为肥胖组,5只作为肥胖抵抗组,检测各组大鼠血清甘油三酯和总胆固醇,附睾周围脂肪组织中PPARγ和aP2 mRNA表达。结果肥胖组大鼠血清甘油三酯水平显著高于对照组(P<0.05);总胆固醇水平均显著高于对照组和肥胖抵抗组(P<0.05,P<0.01);肥胖组PPARγ和aP2 mRNA表达量高于对照组和肥胖抵抗组(P<0.05)。结论高脂饮食诱导产生的肥胖及肥胖抵抗大鼠在脂肪组织PPARγ和aP2 mRNA表达上存在差异,肥胖大鼠脂肪合成能力增强。     

SOCS-3抑制对膳食诱导肥胖大鼠脂肪细胞PPARγ及aP2表达的影响

目的通过对膳食诱导肥胖大鼠脂肪细胞SOCS-3进行抑制,探讨是否可以恢复瘦素的抗脂肪合成作用。方法采用SOCS-3小发夹RNA（shRNA）慢病毒,感染瘦素抵抗肥胖大鼠成脂诱导分化后的脂肪细胞,检测SOCS-3的抑制效果。再采用50 nmol/L瘦素处理6 h,观察脂肪合成相关基因（PPARγ及aP2）mRNA表达的变化。结果 SOCS-3 shRNA慢病毒可有效抑制脂肪细胞SOCS-3 mRNA的表达,抑制率达50%。50 nmol/L瘦素处理6 h后,感染SOCS-3 shRNA慢病毒组PPARγ及aP2 mRNA的表达显著降低（P〈0.01）,空白对照组和感染阴性对照病毒组的表达无明显变化（P〉0.05）。结论通过抑制膳食诱导肥胖大鼠的脂肪细胞SOCS-3,在一定程度上可以解除脂肪细胞的瘦素抵抗。     

瘦素抵抗肥胖大鼠脂肪组织SOCS-3、PPARγ及ACO mRNA水平的探讨

目的观察高脂饮食诱导的肥胖瘦素抵抗大鼠细胞因子信号转导抑制因子-3(SOCS-3)、过氧化物酶体增殖物激活受体γ(PPARγ)及乙酰辅酶A氧化酶(ACO)mRNA表达水平的变化。方法30只Wistar雄性大鼠,6只为对照组喂饲基础饲料,24只为高脂组喂饲高脂饲料,第8周末按体重增量从高脂组中筛选出8只大鼠作为肥胖组,测定对照组和肥胖组大鼠血清瘦素,附睾脂肪组织中SOCS-3,PPARγ以及ACO mRNA表达。结果肥胖组大鼠体重以及血清瘦素水平均显著高于对照组(P<0.05);肥胖组脂肪组织SOCS-3、PPARγ mRNA水平显著高于对照组(P<0.05),而ACO mRNA则显著低于对照组(P<0.05)。结论高脂饮食诱导的肥胖大鼠存在瘦素信号转导通路的抑制,脂肪酸氧化能力降低,脂肪合成能力增强。     

普洱茶提取物对饮食诱导肥胖大鼠脂质合成相关基因表达的影响

目的观察普洱茶提取物(PTE)对饮食诱导性肥胖大鼠脂质合成相关基因的影响,探讨普洱茶抗肥胖的作用机制。方法30只雄性Sprague-Dawley大鼠随机分为3组(n=10):正常对照组,普通饲料;高脂组,高脂饲料;高脂+PTE组,高脂饲料+PTE。采用高脂饲料建立肥胖大鼠模型,测定大鼠体重和脂肪组织重量,判定减肥效果;采用real-timePCR检测PTE对脂质合成相关基因的表达影响。结果PTE能有效减轻动物体重和脂肪组织重量,显著下调二酰基甘油酰转移酶-1(DGAT1)、固醇辅酶A去饱和酶1(SCD1)和固醇调节元件结合蛋白(SREBP)-1cmRNA的表达。结论PTE可通过调节脂质合成相关基因,减少脂肪的合成,达到预防肥胖的作用。     

n-3多不饱和脂肪酸对肥胖小鼠食欲调节因子表达的影响

【目的】 探讨n-3多不饱和脂肪酸(n-3 PUFAs)对饲料诱导肥胖小鼠食欲调节因子表达的影响。 【方法】 使用3~4周龄C57BL/6J雄性小鼠,随机分为3组,每组15只,分别给予两种高脂饲料(脂肪含量为34.9%,供能比为60%)-n-6PUFAs(来源于葵花籽油)饲料和n-3PUFAs(来源于鱼油)饲料喂养3个月;以正常脂饲料(脂肪含量为4.3%,供能比为10%)作为诱导肥胖鼠的对照。小鼠禁食12 h后,麻醉状态下心脏取血、脑和性腺周围脂肪。血浆瘦素含量测定采用酶联免疫分析法;脂肪组织瘦素及下丘脑瘦素受体、神经肽Y(NPY) 和促阿片-黑素细胞皮质素原(POMC)mRNA表达采用实时荧光定量PCR进行。 【结果】 两组高脂饲料诱导的肥胖小鼠体重和血浆瘦素浓度均高于正常脂饲料组小鼠,但n-3PUFAs高脂饲料组肥胖小鼠在两项指标的增高程度显著低于n-6PUFAs高脂饲料组肥胖小鼠。与正常脂饲料喂养小鼠相比,n-6PUFAs高脂饲料诱导肥胖小鼠脂肪组织瘦素和下丘脑瘦素受体、POMC mRNA表达水平显著升高,而NPY mRNA水平降低;n-3PUFAs高脂饲料诱导肥胖小鼠的上述4种基因mRNA表达则未发生变化。 【结论】 n-3PUFAs可减轻肥胖状态下瘦素及其受体、NPY、POMC等食欲调节因子表达的异常,在肥胖发生中起着积极作用。     

n-3多不饱和脂肪酸对肥胖小鼠瘦素基因启动子区DNA甲基化的影响

目的 从基因启动子区DNA甲基化环节, 探讨n-3多不饱和脂肪酸(n-3 polyunsaturated fatty acids, n-3 PUFAs)对肥胖状态下瘦素表达的表观遗传调控机制。方法 3~4周龄C57BL/6J雄性小鼠30只, 随机被分为3组(每组10只), 分别给予高脂饲料、鱼油n-3 PUFAs高脂饲料(脂肪含量均为34.9%, 供能比为40%)以及正常脂饲料(脂肪含量为4.3%, 供能比为10%)喂养4个月以诱导肥胖。喂养结束时取性腺周围脂肪组织, 应用RT-PCR检测脂肪组织瘦素mRNA水平;应用亚硫酸盐修饰直接测序(bisulfite sequencing-PCR, BSP)法检测瘦素基因启动子区CpG甲基化程度;应用染色质免疫共沉淀-荧光定量PCR(CHIP-RT-PCR)技术测定瘦素基因启动子区结合的DNA甲基化转移酶(DNMTs)、甲基化CpG结合蛋白2(MECP-2)以及RNA聚合酶2(Poly II)的变化。结果 与正常脂饲料组小鼠相比, 脂肪组织中瘦素mRNA 表达在高脂饲料诱导肥胖小鼠明显增加, 而在鱼油高脂饲料组肥胖小鼠无变化。基因启动子区甲基化结果显示, 高脂肥胖小鼠瘦素基因启动子区CpG位点甲基化程度、DNMT1、DNMT3a、DNMT3b和MECP-2含量均较正常饲料组显著升高, 并伴随Poly II含量减少;而鱼油高脂饲料组瘦素基因启动子区结合DNMT3a、DNMT3b and MeCP-2增加, 但启动子区MECP-2含量与高脂饲料组比缺有显著降低, DNMT1和Poly II以及CpG位点甲基化程度无改变。结论 肥胖状态下瘦素表达变化可能与基因启动子区DNA甲基化以及结合的相关调控蛋白、RNA聚合酶等有关;n-3 PUFAs对瘦素基因表达的调节也可能是通过对这些蛋白的影响而实现的。     

绿茶多酚对胰岛素抵抗模型大鼠血脂与血压的效应及其机制

目的:利用胰岛素抵抗模型大鼠,探究绿茶多酚(greenteapolyphenols,GTP)调脂降压作用及其作用机制。方法:高脂、高糖和高盐饲料饲养大鼠,饲养6w时,给予GTP,1次/d,连续6w,并于处理前,处理6w和12w测定大鼠血压,以及各组大鼠空腹血糖、血脂、胰岛素水平及血中MDA、TNF-α、Renin、AngⅡ水平和SOD活性。结果:GTP可显著降低胰岛素抵抗模型大鼠血压和血脂,并提高胰岛素敏感指数;同时,降低血中AngⅡ、MDA、TNF-α水平,升高SOD活性。结论:GTP对胰岛素抵抗时发生的高血脂和高血压具有调脂和降压作用,其作用机制与其抗氧化,抑制AngⅡ和TNF-α因子生成有关。     

鱼油摄入对肥胖大鼠脂肪组织、瘦素表达和胰岛素水平的影响

目的探讨鱼油摄入对肥胖大鼠体重增量、脂肪组织、瘦素基因表达、血清瘦素及胰岛素水平的影响。方法雄性Wistar大鼠在高脂(猪油20%WT/WT)饮食8 w后,以体重比对照组重30g及以上(约1个标准差)为标准分出肥胖大鼠,并按体重随机分为两组:猪油组(猪油20/100 WT/WT)和鱼油组(鱼油20/100WT/WT),保留对照组,分别饲以相应饲料,继续饲养4w。腹腔麻醉,心脏穿刺取血并分离血清,测血清瘦素及胰岛素水平;处死大鼠,分离腹膜后、附睾脂肪组织,称湿重,做腹膜后脂肪组织切片,以目镜测微计测脂肪细胞直径;RT-PCR检测脂肪组织瘦素mRNA。结果 (1)鱼油组大鼠体重增量、腹膜后、附睾脂肪组织湿重、脂肪细胞体积显著低于猪油组;其脂肪组织瘦素mRNA表达水平、血清瘦素、胰岛素水平均有降低趋势,但未达到统计学意义上的显著差异。(2)猪油、鱼油两组大鼠血清瘦素水平与血清胰岛素水平均呈显著的相关关系。结论鱼油饮食4w能显著降低肥胖大鼠体重增量、脂肪组织含量,但未能显著降低脂肪组织瘦素mRNA水平、血清瘦素及胰岛素水平。[营养学报,2013,35(2):146-149]     

中链甘油三酯饮食增加过氧化物酶增殖体激活受体γ和脂联素的表达

目的探讨含中链甘油三酯(medium chain triglycerides,MCT)的高脂饮食对血清和脂肪组织中脂联素、过氧化物酶增殖体激活受体γ(PPARγ)水平的影响。方法雄性Wistar大鼠,分别饲喂含MCT和长链甘油三酯(LCT)的高脂饲料,8w后病理检测右侧肾周脂肪细胞的大小。ELISA法检测血清中脂联素、TNF-α、胰岛素的水平。逆转录PCR测定脂肪组织中脂联素、PPARγ mRNA表达水平。结果MCT组大鼠体脂(BFA)、外周脂肪组织的细胞直径小于LCT组。MCT组的血清脂联素含量高于LCT组,两组间血清TNF-α无显著差异。MCT组外周脂肪组织中脂联素、PPARγ mRNA表达水平显著高于LCT组。结论MCT饮食可通过促进PPARγ表达,上调脂联素基因的表达,改善大鼠胰岛素抵抗。     

共轭亚油酸对肥胖大鼠PPARγ基因表达及血清瘦素水平的影响

目的　研究不同剂量共轭亚油酸 (CLA)对饮食诱导肥胖大鼠PPARγ基因、瘦素、血糖、血脂的影响。方法　选用雄性Wistar大鼠 ,随机分为对照组、高脂组、高脂 +CLA组 (每 10 0g饲料含CLA分别为 0 75g、1 5 0g、3 0 0g) ,于第 12周末处死动物 ,计算脂 体比 ,测定大鼠血糖、血脂及瘦素水平 ,并应用RT PCR的方法检测大鼠白色脂肪组织过氧化物酶体增殖物激活受体γ(PPARγ)的表达水平。结果　CLA可降低肥胖大鼠血糖、甘油三酯 (TG)、总胆固醇 (TC)及瘦素水平 ,增加脂肪组织PPARγmRNA的表达水平。结论　CLA可降低肥胖大鼠血糖、血脂 ,并可通过激活PPARγ下调瘦素水平 ,有改善肥胖大鼠的瘦素抵抗作用。     

乌龙茶水浸物对大鼠的减肥作用

[目的]探讨乌龙茶的减肥作用。[方法]选用SD雄性大鼠用高能量高脂肪饲料制备肥胖模型大鼠后,选择其中32只模型鼠,随机分为肥胖对照组、低、中、高剂量组,分别灌服蒸馏水、0.4g/kg.bw、1.2g/kg.bw、2.4g/kg.bw的乌龙茶水浸物30d后,测定体重、体脂及脂肪细胞最大径。[结果]30d后,灌服中、高剂量乌龙茶水浸物的大鼠体重、体重增加、体围、腹膜后与附睾周脂肪组织重量及脂肪系数、附睾周与肩胛间脂肪细胞的最大径明显低于肥胖对照组大鼠,而饲料总摄取量在各组间却无明显差异。中剂量大鼠腹膜后、肾周脂肪系数也明显低于低剂量组大鼠。[结论]乌龙茶具有减肥作用,中剂量可能为适宜剂量。     

青砖茶与绿茶对大鼠脂代谢和抗氧化作用的比较研究

目的分析了青砖茶及绿茶主要生化成分含量及其对大鼠减肥和抗氧化作用。方法选用2种贮藏时间的青砖茶和普通绿茶测定其主要化学成分,选取雄性Wistar大鼠60只,体重为80±5g,随机分为6组,每组10只。空白对照组和模型对照组每天灌胃蒸馏水;阳性对照组每天灌胃Orlistat 0.04g/kg·bw,1年砖剂量组、10年砖剂量组、绿茶剂量组每天灌胃1.5g/kg·bw的相应茶汤。除空白对照组喂饲普通饲料外,其它5组均喂饲高脂营养饲料,试验期6w。定期称体重,测体长,实验结束后颈动脉取血,测血脂及其抗氧化指标,观测大鼠体内脂肪沉着及脏器变化情况。结果 10年青砖茶茶多糖、茶褐素含量最高,其它成分含量最低,而绿茶茶多糖、茶褐素含量最低,其它成分含量最高。青砖茶、绿茶都能显著降低大鼠体重、Lee’s指数、脂肪系数及血脂水平,能显著提高血清HDL-C含量及血清、肝脏SOD、GSH-PX活性,降低血清和肝脏MDA水平,有效减小脂肪细胞直径。其中,青砖茶的效果优于绿茶,10年砖茶优于1年砖茶。结论青砖茶较绿茶更具有减肥降脂、抗氧化作用。     

Prevention of diet-induced obesity by dietary black tea polyphenols extract in vitro and in vivo

Objective

The effects of certain tea components on the prevention of obesity in humans have recently been reported, although it is still unclear whether black tea consumption is beneficial. We obtained black tea extract (BTPE) consisting of polyphenols specific to black tea, and from it, prepared a polymerized polyphenol fraction (BTP). The effectiveness of oral administration of the BTPE was examined in in vitro and in vivo experiments.

Methods

Effects of BTPE or BTP on pancreatic lipase activity were investigated in vitro. Male Wistar rats were administered an oral lipid emulsion containing BTPE at a concentration of 500 or 1000 mg/kg body weight and sequential plasma lipid levels were measured. Female C57BL/6N mice were fed a standard or high-fat diet supplemented with 1% or 5% (w/w) BTPE for 8 wk and changes in body weight were examined.

Results

BTP and BTPE inhibited pancreatic lipase activity with an IC₅₀ of 15.5 and 36.4 μg/mL in vitro, respectively. BTPE suppressed increases in rat plasma triglyceride levels in a dose-dependent manner after oral administration of a lipid emulsion. Furthermore, administration of the 5% BTPE suppressed increases in body weight (P < 0.05), parametrial adipose tissue mass, and liver lipid content (reduced to 56.9% and 81.7% of control mice, respectively, P < 0.05) in mice fed a high-fat diet.

Conclusion

The BTPE may prevent diet-induced obesity by inhibiting intestinal lipid absorption. It was suggested that the major active component in the BTPE was BTP.     

绿茶多酚对高糖高脂饮食大鼠肾纤溶酶原激活物抑制剂表达的影响

目的研究绿茶多酚(GTPs)对高糖高脂饮食大鼠肾纤溶酶原激活物抑制剂-1(PAI-1)表达的影响及机制。方法健康雄性Wistar大鼠随机分为五组:正常对照组(CON)、高糖高脂组(HG)、GTPs干预组(低、中、高剂量绿茶多酚组,G1、G2、G3)。CON组大鼠给予普通饲料,HG组及GTPs干预组给予高糖高脂饲料。喂养100d后处死所有大鼠,测定血清胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、肾组织匀浆液总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)活性和丙二醛(MDA)含量。分别采用荧光实时定量PCR法、免疫印记法测定肾皮质PAI-1mRNA和蛋白表达水平。结果 HG组大鼠血清TC、TG、LDL-C水平和肾皮质MDA含量比CON组明显升高(P<0.05)。与HG组相比GTPs干预组血清TC、TG及LDL-C水平和肾皮质MDA含量均明显降低(P<0.05),T-AOC、SOD、GSH-Px水平升高(P<0.05)。高糖高脂饮食大鼠肾皮质PAI-1mRNA及蛋白表达水平升高,GTPs可以逆转高糖高脂饮食所导致的大鼠肾皮质PAI-1mRNA及蛋白表达水平升高,但三个剂量GTPs干预组之间未见显著性差别。结论绿茶多酚可能通过调节血脂、抗氧化作用、以及降低PAI-1基因及蛋白表达水平从而保护肾脏。     

Black and green tea polyphenols attenuate blood pressure increases in stroke-prone spontaneously hypertensive rats

Oxidative stress was reported to be involved not only in cardiovascular diseases, but also in hypertension. Epidemiologic studies indicated that tea consumption slightly reduces blood pressure. We conducted two studies to determine whether black and green tea can lower blood pressure (BP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP (n=15) were allowed to recover for 2 wk after a transmitter for measuring BP was implanted in the peritoneal cavity. The rats were divided into three groups: the control group consumed tap water (30 mL/d); the black tea polyphenol group (BTP) consumed water containing 3.5 g/L thearubigins, 0.6 g/L theaflavins, 0.5 g/L flavonols and 0.4 g/L catechins; and the green tea polyphenol group (GTP) consumed water containing 3.5 g/L catechins, 0.5 g/L flavonols and 1 g/L polymetric flavonoids. The telemetry system was used to measure BP, which were recorded continuously every 5 min for 24 h. During the daytime, systolic and diastolic BP were significantly lower in the BTP and GTP groups than in the controls. Protein expressions of catalase and phosphorylated myosin light chain (MLC-p) were measured in the aorta by Western blotting. GTP significantly increased catalase expression, and BTP and GTP significantly decreased MLC-p expression in the aorta. These data demonstrate that both black and green tea polyphenols attenuate blood pressure increases through their antioxidant properties in SHRSP. Furthermore, because the amounts of polyphenols used in this experiment correspond to those in approximately 1 L of tea, the regular consumption of black and green tea may also provide some protection against hypertension in humans.     

Decaffeinated green and black tea polyphenols decrease weight gain and alter microbiome populations and function in diet-induced obese mice

Purpose

Decaffeinated green tea (GT) and black tea (BT) polyphenols inhibit weight gain in mice fed an obesogenic diet. Since the intestinal microflora is an important contributor to obesity, it was the objective of this study to determine whether the intestinal microflora plays a role in the anti-obesogenic effect of GT and BT.

Methods

C57BL/6J mice were fed a high-fat/high-sucrose diet (HF/HS, 32% energy from fat; 25% energy from sucrose) or the same diet supplemented with 0.25% GTP or BTP or a low-fat/high-sucrose (LF/HS, 10.6% energy from fat, 25% energy from sucrose) diet for 4 weeks. Bacterial composition was assessed by MiSeq sequencing of the 16S rRNA gene.

Results

GTP and BTP diets resulted in a decrease of cecum Firmicutes and increase in Bacteroidetes. The relative proportions of Blautia, Bryantella, Collinsella, Lactobacillus, Marvinbryantia, Turicibacter, Barnesiella, and Parabacteroides were significantly correlated with weight loss induced by tea extracts. BTP increased the relative proportion of Pseudobutyrivibrio and intestinal formation of short-chain fatty acids (SCFA) analyzed by gas chromatography. Cecum propionic acid content was significantly correlated with the relative proportion of Pseudobutyrivibrio. GTP and BTP induced a significant increase in hepatic 5′adenosylmonophosphate-activated protein kinase (AMPK) phosphorylation by 70 and 289%, respectively (P < 0.05) determined by Western blot.

Conclusion

In summary, both BTP and GTP induced weight loss in association with alteration of the microbiota and increased hepatic AMPK phosphorylation. We hypothesize that BTP increased pAMPK through increased intestinal SCFA production, while GTPs increased hepatic AMPK through GTP present in the liver.

     

茶多酚降血脂抗血栓作用的实验研究

从茶叶中提取茶多酚喂饲实验性高脂血症模型大鼠六周。结果表明,茶多酚组大鼠的血清胆固醇、甘油三酯含量均明显低于高脂对照组(P<0.01),高密度脂蛋白胆固醇明显高于高脂对照组(P<0.05),且呈剂量效应关系。茶多酚组大鼠的红细胞变形能力增强,血浆纤维蛋白原含量下降,体外血栓指标优于高脂对照组(P<0.01)。提示茶多酚具有防治高脂血症的作用,并能改善血液高凝状态,对血浆脂质异常情况下的隐性血栓病交具有一定的疗效。     

富硒绿茶对大鼠载脂蛋白及血液流变学的影响

目的:探讨富硒绿茶对心血管的保护作用。方法:将Wistar大鼠分为4组,分别饲以标准饲料+常规饮水、标准饲料+硒茶、高脂饲料+常规饮水、高脂饲料+硒茶。12w后测定体重、载脂蛋白apoA、apoB、全血比粘度、血浆比粘度、红细胞压积、计算纤维蛋白原比粘度、红细胞聚集指数。结果:高脂对照组(HC)体重明显高于正常对照组(NC)、硒茶组(ST)和高脂硒茶组(HST);ST组和HST组apoA水平明显高于NC组和HC组、apoB/apoA比值明显低于NC组和HC组;ST组全血比粘度和血浆比粘度明显低于NC组,HST组全血比粘度、血浆比粘度及红细胞聚集指数均显著低于HC组。结论:富硒绿茶能显著降低高脂饮食大鼠体重、改善脂蛋白代谢和血流状态,对大鼠心血管系统有一定的保护作用。