共轭亚油酸降血脂及抗动脉粥样硬化作用的研究

目的:探讨共轭亚油酸降血脂及抗动脉粥样硬化形成的作用机制。方法:选用大鼠随机分为正常对照组,高脂模型组,c9,t11CLA:t10,c12CLA=2:1、1:1、1:3、1:6,只含t10,c12CLA共7组。实验至第8周末取血,检测血清胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL)和丙二醛(MDA)、超氧化物歧化酶(SOD)活性。结果:与高脂模型组比较,共轭亚油酸组大鼠血清TC、TG、MDA含量明显降低,HDL、SOD含量明显提高(P<0.05)。结论:共轭亚油酸具有降低血脂和抗动脉粥样硬化的作用。     

共轭亚油酸降血脂及抗动脉粥样硬化作用的研究

目的：探讨共轭亚油酸降血脂及抗动脉粥样硬化形成的作用机制。方法：选用大鼠随机分为正常对照组,高脂模型组,c9,t11CLA：t10,c12CLA=2：1、1：1、1：3、1：6,只含t10,c12CLA共7组。实验至第8周末取血,检测血清胆固醇（TC）、三酰甘油（TG）、高密度脂蛋白（HDL）、低密度脂蛋白（LDL）和丙二醛（MDA）、超氧化物歧化酶（SOD）活性。结果：与高脂模型组比较,共轭亚油酸组大鼠血清TC、TG、MDA含量明显降低,HDL、SOD含量明显提高（P〈0.05）。结论：共轭亚油酸具有降低血脂和抗动脉粥样硬化的作用。     

共轭亚油酸对高脂血症大鼠脂质代谢及visfatin基因表达水平的影响

目的建立高脂血症大鼠模型,分析共轭亚油酸（CLA）对其脂质代谢和visfatin基因表达水平的影响,为进一步研究CLA对脂肪代谢的调控机制奠定基础。方法用高脂饲料饲喂雄性Wistar大鼠,4周后断尾采血测定血清甘油三酯（TG）、总胆固醇（CHO）和血糖（GLU）含量,将构建成功的高脂血症大鼠分为实验组和对照组,实验组每天定时灌胃CLA（0.8 mL/0.1 kg）,每周定时称重,记录采食量;4周后眼球采血,测定血清中GLU、CHO、TG、低密度脂蛋白（LDL）、高密度脂蛋白（HDL）水平;断颈处死大鼠,分离体脂并提取肝脏总RNA,半定量RT-PCR分析visfatin基因表达水平。结果高脂饲料饲喂4周后,模型组大鼠血清TG、CHO、GLU明显高于对照组大鼠（P〈0.05）,表明高脂大鼠模型构建成功。灌胃CLA 4周后,实验组大鼠体重、体脂和采食量低于对照组大鼠（P〈0.05）,血清中GLU、CHO、TG、LDL含量明显降低,但实验组HDL浓度升高。RT-PCR实验结果表明,实验组大鼠visfatin基因表达水平明显低于对照组大鼠（P〈0.05）。结论CLA能降低高脂血症大鼠摄食量,改善高血脂大鼠脂质代谢,并能降低visfatin基因的表达水平。     

下丘脑Orexin 对肥胖大鼠能量代谢的影响

目的:探讨下丘脑注射OXR-1选择性受体拮抗剂ACT-335827对肥胖大鼠代谢的效果。方法:通过高脂饮食建立肥胖大鼠模型,采用CODA 8通道高通量非侵入性血压系统(EMKA)测量血压;所有脂类都使用商品酶试剂盒和TOSHIBA-40FR全自动分析仪测量;空腹血糖采用葡萄糖氧化酶法;空腹胰岛素采用放射免疫法测定。肥胖大鼠出现代谢紊乱后,给予ACT-335827处理,检测大鼠体重、血压、脂肪、甘油三酯、总胆固醇、高密度脂蛋白、低密度脂蛋白、游离脂肪酸(NEFA)、瘦素、空腹血糖及空腹胰岛素等的变化。结果:与普通饮食组相比,经过10周高脂饮食,高脂饮食组大鼠体重显著升高(P0.05),给予ACT-335827处理后,普通大鼠的体重、血压、脂肪含量、脂代谢等均无明显变化;与高脂饮食和高脂饮食加生理盐水处理组大鼠比较,高脂饮食加ACT-335827处理组肥胖大鼠的体重显著下降(P0.05),腹部和附睾脂肪含量下降(P0.05),低密度脂蛋白、甘油三酯、总胆固醇、瘦素水平下降(P0.05),空腹血糖及空腹胰岛素也显著降低(P0.05),但血压、肠系膜脂肪和肩胛棕色脂肪、高密度脂蛋白和NEFA无明显变化(P0.05)。结论:ACT-335827对肥胖大鼠的代谢紊乱具有改善作用,对肥胖大鼠有一定的减肥作用。     

不同脂肪高脂日粮诱发胰岛素抵抗综合征大鼠模型的比较

目的分析猪油、豆油、氢化椰子油、乳脂四种不同脂肪的高脂日粮分别诱发胰岛素抵抗综合征（IRS）大鼠的血液生化指标差异,为此类模型的建立及实验研究提供参考。方法雄性SD大鼠随机分为5组,对照组给予普通日粮,高脂组给予脂肪热量比相同的高脂日粮。喂养6周,每两周测定空腹血糖、甘油三酯（TG）、高密度脂蛋白胆固醇（HDL-c）、总胆固醇（TC）、胰岛素,根据胰岛素敏感性指数（ISI）=ln1/（FPG×FINS）评定大鼠的胰岛素敏感性。结果6周后,猪油组、乳脂组、豆油组血清胰岛素均显著高于对照组（P〈0.05）;乳脂组血清TG显著高于其它高脂组（P〈0.05）;高脂组血清HDL-c均显著低于对照组（P〈0.05）并以豆油组下降幅度最大;猪油组、乳脂组ISI显著低于对照组（P〈0.05）;而各组间血清总胆固醇、血糖及体重无明显差异（P〉0.05）。结论4种高脂日粮诱发IRS大鼠模型的综合效果依次为乳脂、猪油、豆油、氢化椰子油。     

游泳运动对大鼠血清高密度脂蛋白胆固醇水平的影响

本文观察了游泳运动对摄取高脂饲料大鼠血清高密度脂蛋白胆固醇(HDL-C)及高密度脂蛋白胆固醇/总胆固醇(HDL—C/TC)百分比值的影响。52头雄性成年大鼠分为四组:对照组(高脂饲料)、运动1组(高脂饲料 强制游泳0.5小时/天)、运动2组(高脂饲料 强制游泳2小时/天)和运动8组(高脂饲料 强制游泳4小时/天),每周游5天,连续3周。实验高脂饲料配方为:基础饲料93％,椰子油5％、胆固醇1.5％和胆盐0.5％。结果表明,高饱和脂肪和高胆固醇饲料引起血清TC升高,HDL-C和HDL-C/TC百分比值降低。游泳运动则可减轻体重,降低血清TC水平,显著地升高HDL-C和HDL-C/TC百分比值(P<0.001)。显示HDL-C的升高幅度与一定的运动时间延长有关。可见适宜的运动能改善高脂饲料所致的血脂异常。     

不同性别大鼠在2型糖尿病造模过程中的稳定性

目的研究不同性别大鼠在2型糖尿病造模过程中的成功率及模型的稳定性。方法高糖高脂饮食联合腹腔注射小剂量链脲佐菌素诱导建立雄、雌性大鼠2型糖尿病模型。成模后所有大鼠每周固定时间测血糖和体重。观察24周后,心脏穿刺取血,测定空腹血糖（FPG）、血清胰岛素（FINS）、HbA1c、甘油三脂（TG）、胆固醇（TC）、高密度脂蛋白-胆固醇（HDL-C）、低密度脂蛋白-胆固醇（LDL-C）。结果单纯高糖高脂饮食喂养,雄、雌性大鼠血糖与正常组无显著差异;STZ注射后,雄性大鼠血糖升高并逐渐平稳,而雌性需两次STZ注射,模型才比较稳定。实验结束时,雄、雌性糖尿病大鼠FPG、FINS、HOMA-IR以及TG、TC、LDL-C均显著升高,说明模型存在胰岛素抵抗和脂代谢紊乱。结论高糖高脂饲料加一次性小剂量链脲佐菌素腹腔注射,可成功建立雄性大鼠2型糖尿病模型,而同等剂量,雌性模型需两次STZ。雄、雌性糖尿病大鼠模型具有高血糖、脂质代谢紊乱和胰岛素抵抗特点。造模成功率及稳定性与性别有关,雄性大鼠较雌性大鼠成模率高,稳定性好,且耗时更短。     

共轭亚油酸对HepG2细胞脂质沉积的影响

目的:研究共轭亚油酸(conjugated linoleic acid,CLA)对HepG2细胞脂肪沉积的影响,以探讨其对肝脏脂肪沉积的可能机制.方法:体外培养HepG2细胞,不同浓度CLA(0、10、50、100 μmol.1-1)作用24小时后,100 nmol.1-1胰岛素作用1小时.以比色法测定培养液中游离脂肪酸的含量,油红O染色观察细胞脂肪沉积,Western-blot检测Akt和P-Akt蛋白表达.结果:随着CLA浓度增加,培养液中的游离脂肪酸含量显著降低,细胞中红染脂滴增多,Western-blot结果发现,Akt蛋白的磷酸化水平增高.结论:CLA可以增加细胞内脂肪合成和细胞中Akt蛋白的磷酸化水平.     

共轭亚油酸甘油酯对大鼠血清脂肪酸组成影响的研究（英文）

目的:研究共轭亚油酸甘油酯对高脂饮食大鼠血清脂肪酸组成变化的影响;方法:60只SD大鼠随机分为5组:正常对照组、高脂对照组,共轭亚油酸甘油酯低(2 g/kg·bw)、中(4 g/kg·bw)、高(6 g/kg·bw)剂量组,除基础对照组外其余各组均喂饲高脂饲料,建立高脂模型,以灌胃方式给予受试物,6周后取血清测定其脂肪酸组成。采用一步法直接对血清中脂肪酸进行甲酯化,气相色谱毛细管柱分离,氢火焰离子化检测器(FID)定性定量分析;结果:共轭亚油酸甘油酯低、中、高剂量组大鼠血清中单不饱和脂肪酸含量为25.66%,18.74%,17.72%,与高脂对照组相比显著性下降(P0.01),各剂量组饱和脂肪酸和多不饱和脂肪酸含量分别为48.08%,48.52%,51.15%和27.03%,29.28%,31.13%,与高脂对照组相比显著性升高(P0.01)。几种代表性脂肪酸如各剂量组中的油酸、亚油酸与高脂对照组相比分别增加了26.48%,41.56%,51.26%和9.18%,8.61%,8.73%,各剂量组中棕榈酸与高脂对照组相比降低了5.28%,8.80%,10.92%。结论:共轭亚油酸甘油酯能够增加大鼠血清中饱和脂肪酸和多不饱和脂肪酸的含量,减少单不饱和脂肪酸含量,改变血清脂肪酸组成。     

16S rDNA测序研究高脂饮食诱导的高脂血症大鼠肠道菌群变化

目的 通过高脂饮食诱导大鼠高脂血症,采用16S rDNA测序检测高脂血症大鼠肠道菌群变化情况.方法 SD大鼠20只(清洁级),按体质量随机分为模型组和对照组,对照组大鼠给予维持饲料,模型组大鼠给予高脂饲料.1周后检测血清总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)和高密度脂蛋白胆固醇(HDL-C...     

Isomers of conjugated linoleic acid decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in post-prandial adult sedentary or trained Wistar rat

The respective effects and interactions of supplementation with two conjugated linoleic acid (CLA) isomers and exercise on plasma metabolic profile, activity of lipogenic enzymes and cellularity in two adipose tissue sites, those of the liver and heart, were examined in adult Wistar rats. Rats that were either sedentary or exercise-trained by treadmill running were fed one of four diets: a diet without CLA; a diet with either 1% cis 9, trans 11 CLA or 1% trans 10, cis 12 CLA; or a mixture of both isomers (1% of each) for 6 weeks. We observed that the exercise decreased lipogenic enzyme activities in epididymal and perirenal adipose tissue. Plasma cholesterol, insulin, and leptin concentrations were lower in exercise-trained rats than in sedentary rats. The ingestion of either CLA mixture or the trans 10, cis 12 CLA increased lipogenic enzyme activities in epididymal tissue and more markedly in perirenal adipose tissue, especially in sedentary rats, and without affecting adipose tissue weight or cellularity. A similar effect of trans 10, cis 12 CLA was observed in regard to malic enzyme activity in the liver. In addition, this isomer decreased plasma lipid and urea concentrations and increased plasma 3-hydroxybutyrate levels. The ingestion of cis 9, trans 11 CLA increased fatty acid synthase activity in perirenal adipose tissue in sedentary rats and decreased plasma cholesterol and leptin concentrations. These results show that isomers of CLA decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in adult sedentary or exercise-trained rat, thus suggesting a stimulation of adipose tissue turnover.     

Conjugated docosahexaenoic acid inhibits lipid accumulation in rats

Conjugated linoleic acid (CLA), which contains a conjugated double-bond system, and n-3 highly unsaturated fatty acids such as docosahexaenoic acid (DHA) are widely known to improve lipid metabolism. To examine the possibility that a fatty acid with a combination of these structural features might have stronger physiological effects, we prepared conjugated DHA (CDHA) by alkaline isomerization of DHA and examined its effects on lipid and sugar metabolism in rats. Rats were force fed with 200 mg of test oils [linoleic acid (LA), DHA, CLA or CDHA] everyday for 4 weeks. Compared with the animals from the other groups, those in the CDHA group showed a significant weight loss in white adipose tissue (57% of adipose tissue weight in the LA group) and significant decreases in the levels of liver triacylglycerol (TG; 65% of TG level in the LA group) as well as total cholesterol (TC; 88% of TC level in the LA group), indicating suppression of lipid accumulation in the liver and adipose tissue. In addition, plasma TG and TC levels significantly decreased (69% of TG level and 82% of TC level in the LA group), indicating improved lipid metabolism. In the liver, the fatty acid synthesis system was inhibited and the fatty acid beta-oxidation system was activated, whereas the free fatty acid, glucose and tumor necrosis factor alpha levels in the plasma were lowered following CDHA administration. Hence, intake of CDHA appears to suppress the accumulation of fat in the liver and epididymal adipose tissue and improves lipid and sugar metabolism in rats.     

Chromium picolinate and conjugated linoleic acid do not synergistically influence diet- and exercise-induced changes in body composition and health indexes in overweight women

This study assessed the effects of combined chromium picolinate (CP) and conjugated linoleic acid (CLA) supplementation on energy restriction and exercise-induced changes in body composition, glucose metabolism, lipid lipoprotein profile and blood pressure in overweight, premenopausal women. For 12 weeks, 35 women [age 36+/-1 years (mean+/-S.E.M.); BMI 28.0+/-0.5 kg/m2] were counseled to consume a 2092 kJ/day (500 kcal/day) energy deficit diet and performed 30 min of moderate-intensity walking or jogging 5 days/week. The women were randomly assigned to ingest either CP-CLA [400 mug chromium (Cr), 1.8 g CLA in 2.4 g tonalin oil, n=19] or placebo (<0.1 microg Cr, 2.4 g canola oil, n=16). Compared to baseline, urinary Cr excretion increased 22-fold, plasma CLA isomer 18:2 (c9,t11) content increased 79% and plasma CLA isomer 18:2 (t10,c12) became detectable in CP-CLA and were unchanged in Placebo. Over time, body weight decreased 3.5+/-0.5% (CP-CLA -2.6+/-0.5; placebo -2.5+/-0.5 kg) and fat mass decreased 8.9+/-1.3% (CP-CLA -2.7+/-0.5, placebo -2.4+/-0.5 kg), with no differences in responses between groups. Fasting blood hemoglobin A1c, plasma glucose and insulin, a homeostatic assessment of insulin resistance, serum total cholesterol (CHOL), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol, triacylglycerol (TG), CHOL/HDL ratio, TG/HDL ratio and sitting systolic and diastolic blood pressures were not changed over time or influenced by CP-CLA. The use of a combined CP and CLA supplement for 3 months does not affect diet- and exercise-induced changes in weight and body composition or improve indexes of metabolic and cardiovascular health in young overweight women.     

The effects of t10,c12 CLA isomer compared with c9,t11 CLA isomer on lipid metabolism and body composition in hamsters

The objective of the present study was to examine the effects of two different isomers of conjugated linoleic acid (CLA), c9,t11 CLA and t10,c12 CLA, compared with linoleic acid (LA) used as control, on body composition, lipoprotein profile, hepatic lipids and fecal fat content in hamsters. Animals were assigned to the three diet groups (n=15) during 28 days. The diet was composed of 2% of the experimental fat, and throughout the experimental protocol, the hamsters experienced similar food intake. No significant differences were noted in body weight gain among the three diet groups. However, the t10,c12 CLA-fed animals showed higher low-density lipoprotein cholesterol (LDL-C) concentrations (0.9+/-0.1 mmol/L) than those who ingested either LA (0.6+/-0.1 mmol/L) or c9,t11 CLA isomer (0.7+/-0.1 mmol/L), although the t10,c12 CLA consumption decreased hepatic cholesterol and triglycerides and increased fecal fat content compared with the other two groups. Under the present experimental conditions, the dietary c9,t11 CLA isomer showed no positive beneficial effect on plasma lipids. Furthermore, the t10,c12 CLA isomer induced undesirable higher LDL-C, although it reduced hepatic lipids and fat digestibility in hamsters.     

Dietary conjugated linoleic acid reduces body fat mass and affects gene expression of proteins regulating energy metabolism in mice

ICR and C57BL/6J mice were fed experimental diets containing either a 2% fatty acid preparation rich in conjugated linoleic acid (CLA) or a preparation rich in linoleic acid and free of CLA for 21 days. CLA greatly decreased weights of white adipose tissue and interscapular brown adipose tissue in the two strains. CLA reduced mRNA levels of glucose transporter 4 (Glut 4) in white and brown adipose tissue of both strains. A CLA-dependent decrease in mRNA levels of peroxisome proliferator activated receptor (PPAR) gamma was seen in interscapular brown adipose tissue of both strains and in white adipose tissue of C57BL/6J but not ICR mice. Dietary CLA was found to cause a decrease in the mRNA levels of uncoupling protein (UCP) 1 in brown adipose tissue when the value was corrected for the expression of a house-keeping gene (beta-actin) in the two strains. Uncorrected values were, however, indistinguishable between the animals fed the CLA diet and CLA-free diet. UCP 3 expression in brown adipose tissue was much lower in mice fed the CLA diet than in those fed the control diet in both strains. In contrast, CLA greatly up-regulated the gene expression of UCP 2 in brown adipose tissue. Dietary CLA also increased UCP 2 mRNA level in skeletal muscle. It is apparent that dietary CLA decreases white and brown adipose tissue mass, accompanying changes in the gene expression of proteins regulating energy metabolism in white and brown adipose tissues, and skeletal muscle of mice.     

9 cis,11 trans conjugated linoleic acid (CLA) is synthesised and desaturated into conjugated 18:3 in bovine adipose tissues

Although endogenous synthesis of conjugated linoleic acid (CLA) in the mammary gland of lactating cows has been already well documented, no study has determined so far as to which tissue and/or organ is involved in CLA synthesis in the growing ruminant except one study showing that CLA synthesis does not occur in ruminant liver. In this context, adipose tissue appears to be a good candidate for endogenous synthesis of CLA in the growing ruminant. The aim of this study was to compare the respective metabolisms of 11trans 18:1 (vaccenic acid, VA) and 9cis,11trans 18:2 (rumenic acid) to that of stearic acid (the preferential substrate of Δ9 desaturase) in adipose tissues (subcutaneous, SC and intermuscular, IM) of six Charolais steers by using the in vitromethod of incubated tissue slices. Samples of SC and IM adipose tissues were incubated at 37°C for 16 h under an atmosphere of 95% O2/5% CO2 in a medium supplemented with 0.75 mM of fatty acid (FA) mixture (representative of circulating non-esterified FA) and 186 μM [1-14C]-18:0 or 58.6 μM [1-14C]-VA or 56 μM [1-14C]-9cis,11trans CLA. Viability of explants was verified by measuring metabolic functions (glucose uptake and glucose-6-phosphate dehydrogenase activity). After 16 h of incubation, FA uptake was similar for all FA (18:0, VA and 9cis,11trans 18:2) in both SC and IM adipose tissues (around 40%). Once in adipose tissue, all FA were preferentially esterified (>80% of cell FA) favouring neutral lipid synthesis (around 90% of esterified FA). Stearic acid was highly (27%) desaturated into oleic acid in SC adipose tissue whereas this desaturation was much lower (6.8%) in IM adipose tissue (P < 0.0001). VA was desaturated into 9cis,11trans CLA at a low extent of about 2.5% to 4.4% in both adipose tissues probably because of a limited affinity of Δ9 desaturase for VA. 9cis,11trans CLA was itself converted by desaturation into 6cis, 9cis,11trans 18:3 at the intensity of 10.8% and 14.5% of cell 9cis,11trans CLA in SC and IM adipose tissues, respectively. In conclusion, bovine adipose tissues of the growing ruminant were especially involved in the endogenous synthesis of CLA from VA and in its desaturation into conjugated derivative, mainly 6cis, 9cis,11trans 18:3, of which biological properties need to be elucidated.     

Dietary effect of conjugated linoleic acid on lipid levels in white adipose tissue of Sprague-Dawley rats.

We examined the effect of dietary conjugated linoleic acid (CLA) on lipid parameters in the liver, white adipose tissue (WAT) and brown adipose tissue (BAT) of Sprague-Dawley rats and found that it reduced the levels of triglycerides and non-esterified fatty acid in the liver and WAT without significant change in the BAT lipid levels. These results suggest that CLA has an obesity-preventing action.     

Fucoxanthin-rich seaweed extract suppresses body weight gain and improves lipid metabolism in high-fat-fed C57BL/6J mice

An ethanol extract of fucoxanthin-rich seaweed was examined for its effectiveness as a nutraceutical for body fat-lowering agent and for an antiobese effect based on mode of actions in C57BL/6J mice. Animals were randomized to receive a semi-purified high-fat diet (20% dietary fat, 10% corn oil and 10% lard) supplemented with 0.2% conjugated linoleic acid (CLA) as the positive control, 1.43% or 5.72% fucoxanthin-rich seaweed ethanol extract (Fx-SEE), equivalent to 0.05% or 0.2% dietary fucoxanthin for six weeks. Results showed that supplementation with both doses of Fx-SEE significantly reduced body and abdominal white adipose tissue (WAT) weights, plasma and hepatic triglyceride (TG), and/or cholesterol concentrations compared to the high-fat control group. Activities of adipocytic fatty acid (FA) synthesis, hepatic FA and TG synthesis, and cholesterol–regulating enzyme were also lowered by Fx-SEE supplement. Concentrations of plasma high-density lipoprotein-cholesterol, fecal TG and cholesterol, as well as FA oxidation enzyme activity and UCP1 mRNA expression in epididymal WAT were significantly higher in the Fx-SEE groups than in the high-fat control group. CLA treatment reduced the body weight gain and plasma TG concentration. Overall, these results indicate that Fx-SEE affects the plasma and hepatic lipid profile, fecal lipids and body fat mass, and alters hepatic cholesterol metabolism, FA synthesis and lipid absorption.