肥胖大鼠抵抗素的基因表达及共轭亚油酸对其影响的研究

目的研究饮食诱导肥胖大鼠胰岛素抵抗形成过程中脂肪组织抵抗素基因的表达水平和共轭亚油酸(CLA)对其的影响,探讨抵抗素的作用及其与过氧化物酶体增殖物活性受体γ(PPARγ)之间的关系。方法选用雄性Wistar大鼠,分为对照组、高脂组、高脂+CLA组(每100g饲料含CLA分别为0.75g、1.50g、3.00g),每组10只大鼠,观察CLA对肥胖大鼠胰岛素和血糖水平的影响,并应用逆转录聚合酶链反应检测抵抗素和PPARγ的表达水平。结果高脂组大鼠血清胰岛素和血糖水平分别为(11.11±2.73)mIU/L和(5.09±0.66)mmol/L,CLA可降低肥胖大鼠的血清胰岛素和血糖水平,低、中、高剂量组胰岛素水平分别为(6.99±1.77)mIU/L,(7.36±1.48)mIU/L,(7.85±1.60)mIU/L,血糖水平分别为(4.28±0.72)mmol/L、(4.18±0.55)mmol/L、(4.06±0.63)mmol/L,且高脂组大鼠脂肪组织抵抗素、PPARγmRNA的表达较基础组增强,CLA可增加肥胖大鼠脂肪组织抵抗素、PPARγmRNA的表达水平。结论肥胖大鼠脂肪组织抵抗素mRNA表达较基础组增加,CLA可通过激活PPARγ上调抵抗素基因的表达,从而改善胰岛素抵抗。     

共轭亚油酸对胰岛素抵抗大鼠葡萄糖运载体4蛋白表达影响的研究

目的通过研究共轭亚油酸（conjugated linoleic acid,CLA）对饮食诱导胰岛素抵抗大鼠葡萄糖运载体4（glucose transporter4,GLUT4）蛋白表达的影响,探讨CLA抗糖尿病作用的机制。方法选用雄性Wistar大鼠,用随机数字表法按体重随机分为对照组、高脂组、高脂＋CLA组（每100g饲料含CLA分别为0．75g、1．50g．3．00g）,每组动物10只,观察CLA对胰岛素抵抗大鼠胰岛素、血糖水平的影响,并应用Western blot方法检测大鼠骨骼肌GLUT4蛋白的表达水平。结果高脂组大鼠血清胰岛素和糖血水平分别为（11．11±2．73）μU／ml、（5．09±0．66）mmol／L,CLA可降低肥胖大鼠的高胰岛素、高糖血症,低、中、高剂量组胰岛素水平分别为（6．99±1．77）μU／ml、（7．36±1．48）μU／ml、（7．85±1．60）μU／ml,血糖水平分别为（4．28±0．72）mmol／L、（4．18±0．55）mmol／L、（4．06±0．63）mmol／L,且高脂组大鼠骨骼肌GLUT4蛋白的表达水平较基础组降低,CLA可增加高脂组大鼠骨骼肌GLUT4蛋白的表达水平。结论CLA可通过增加胰岛素抵抗大鼠骨骼肌GLUT4蛋白的表达水平,改善胰岛素抵抗。     

GDM大鼠胎盘脂联素基因表达水平与胎鼠出生体重的关系

目的:探讨妊娠期糖尿病大鼠胎盘脂联素与胎鼠出生体重的关系。方法:育龄雌性SD大鼠受孕后随机分为正常妊娠组、妊娠期糖尿病组、共轭亚油酸治疗组。腹腔内注射45mg/kg链尿佐菌素,建立妊娠期糖尿病大鼠模型。注射药物3天后用共轭亚油酸3.0g/(kg·d)灌胃至孕19天,建立共轭亚油酸治疗组大鼠模型。孕19天后解剖大鼠,计数胚胎存活数并测量胎鼠体重。采用葡萄糖氧化酶法测定血糖;采用放射免疫法测定血清胰岛素;采用ELISA试剂盒检测大鼠血清脂联素和胎盘组织脂联素浓度;采用RT-PCR技术检测脂肪组织脂联素和过氧化物增殖物激活受体γmRNA的表达和胎盘组织脂联素mRNA的表达,并进行半定量分析。结果:①共轭亚油酸可降低妊娠期糖尿病大鼠血糖和胰岛素水平,增加脂肪组织中过氧化物增殖物激活受体-γmRNA、脂联素mRNA的表达和胎盘组织中脂联素mRNA的表达水平,相应地,妊娠期糖尿病大鼠血清中和胎盘组织中脂联素的浓度也升高。②3组大鼠的胚胎存活数无统计学差异。③胎盘脂联素mRNA表达水平与胎鼠出生体重呈显著负相关关系。结论:①共轭亚油酸可降低妊娠期糖尿病大鼠血糖水平,并改善血糖升高后刺激胰岛素大量分泌的状态,改善胰岛素抵抗。②共轭亚油酸可通过激活过氧化物增殖物激活受体γ来提高妊娠期糖尿病大鼠脂联素水平。③胎盘组织有脂联素基因的表达,妊娠期糖尿病病理状态可影响脂联素基因在胎盘的表达水平,共轭亚油酸可上调脂联素mRNA的表达水平,并且胎盘组织中脂联素浓度升高。④妊娠期糖尿病病理状态对胚胎存活数影响不大,但胎鼠出生体重增加。⑤胎盘来源的脂联素可能参与了胎儿生长发育的调节。     

妊娠期糖尿病胎儿代谢的相关研究

目的:通过测定妊娠期糖尿病(GDM)脐血脂联素、胰岛素、C肽、糖化血红蛋白水平,探讨GDM对胎儿代谢水平的影响。方法:采用放射免疫法测定30例GDM患者及26例正常孕妇脐血脂联素、胰岛素、C肽水平,采用乳胶增强的免疫竞争抑制法测定脐血糖化血红蛋白水平。结果:GDM组脐血脂联素水平为(20.74±5.66)μg/ml,明显低于对照组(26.66±8.43)μg/ml,脐血胰岛素、糖化血红蛋白水平分别为(31.53±14.63)uIU/ml,(4.9±0.7)%,明显高于对照组,差异有统计学意义。两组脐血脂联素水平与脐血胰岛素、糖化血红蛋白呈明显负相关。结论:宫内暴露于GDM不良环境因素下可引起胎儿脂联素水平的下降及胰岛素、C肽、糖化血红蛋白水平的升高。胎儿代谢水平的改变影响了胎儿的生长发育,还可能与将来子代的代谢性疾病具有相关性。     

共轭亚油酸对胰岛素抵抗大鼠ap2基因表达的影响

目的通过研究共轭亚油酸(CLA)对饮食诱导胰岛素抵抗大鼠脂肪酸连接蛋白(ap2)基因表达的影响,探讨CLA抗糖尿病作用的机制。方法选用雄性Wistar大鼠,随机分为对照组、高脂组、高脂+CLA组(每100g饲料含CLA分别为0·75g、1·50g、3·00g),每组动物10只,观察CLA对胰岛素抵抗大鼠胰岛素、血糖水平的影响,并应用RT-PCR的方法检测ap2、过氧化物酶体增殖物活性受体γ(PPARγ)的表达水平。结果高脂组大鼠血清游离脂肪酸(FFA)、胰岛素和糖血水平显著高于基础组,CLA可降低胰岛素抵抗大鼠血清FFA、血糖、胰岛素水平,并可增加其脂肪组织ap2、PPARγmRNA的表达水平。结论CLA可通过激活PPARγ上调脂肪酸连接蛋白基因的表达,改善肥胖大鼠的胰岛素抵抗。     

非酒精性脂肪性肝病患者脂联水平检测及意义

目的 检测非酒精性脂肪性肝病(NAFLD)患者血清脂联素的水平并探讨其临床意义.方法 选取60例无糖尿病的NAFLD患者(NAFLD组)和40例健康对照者(对照组),测定两组的空腹血糖、血脂、胰岛素和脂联素水平,计算稳态模型评估法胰岛素抵抗指数(HOMA-IRI).结果 NAFLD组血清脂联素水平明显低于对照组[(8.04±3.20)μg/ml比(12.53±8.50)μg/ml,P＜0.001];脂联素与体重指数(BMI)、腰围、天冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、γ-谷氨酰基转移酶(GGT)、甘油三酯(TG)、HOMA-IRI呈负相关;BMI、HOMA-IRI为脂联素水平的独立影响因素.结论 NAFLD患者血清脂联素水平降低,脂联素可能参与了NAFLD患者胰岛素抵抗及动脉粥样硬化的发病过程.     

妊娠期高血压疾病患者血清脂联素水平的变化与胰岛素抵抗的关系

目的:探讨不同程度妊娠期高血压疾病(HDCP)患者血清脂联素(APN)水平变化及其与胰岛素抵抗的关系。方法:以100例妊娠期高血压疾病孕妇为研究对象,其中轻度子痫前期69例,重度子痫前期31例;选取同期100例正常孕晚期孕妇为对照组。采用酶联免疫吸附法(ELISA法)检测孕妇血清脂联素水平,同时检测空腹血糖(FBG)、空腹胰岛素(FINS)水平,计算胰岛素抵抗指数(IRI)。结果:轻度、重度子痫前期患者血清脂联素水平分别为(9.29±3.30)μg/ml和(7.53±2.68)μg/ml,明显低于对照组(11.22±2.75)μg/ml,差异有统计学意义(P<0.01),轻度、重度子痫前期患者胰岛素抵抗指数明显高于对照组(P<0.01),脂联素水平与胰岛素抵抗指数呈显著负相关(r=-0.750,P<0.01)。结论:脂联素水平在妊娠期高血压疾病患者中明显降低,脂联素水平与胰岛素抵抗指数呈显著相关性,提示脂联素在妊娠期高血压疾病发病中可能起着一定的作用,其作用机制与增强胰岛素抵抗有关,可以作为HDCP发病及严重程度的一个预测指标。     

不同脂肪酸对脂肪细胞脂联素及PPARγ基因表达影响

目的用不同种类、不同浓度的脂肪酸处理体外培养的3T3-L1成熟脂肪细胞,观察处理前后脂联素(ad-iponectin)及过氧化物酶体增殖物激活受体γ(PPARγ)基因mRNA的表达水平,及两者之间是否存在相互关系。方法运用实时荧光定量PCR方法检测体外培养并诱导分化成熟的3T3-L1脂肪细胞经一定浓度脂肪酸处理后,脂联素及PPARγ基因mRNA的表达水平。结果棕榈酸(PA)在低浓度(25μmol/L)时能明显上调脂联素及PPARγmRNA的表达,比对照组增加53%(P<0.05),其余浓度均呈表达下降;油酸(OA)和亚油酸(LA)则在浓度为25、50、100μmol/L时上调脂联素及PPARγmRNA的表达,在50μmol/L时上调作用最为明显,随着浓度的继续增加脂联素表达下降,呈剂量依赖关系,浓度越高,表达越低。结论油酸和亚油酸在一定浓度范围内上调3T3-L1脂肪细胞脂联素基因表达,棕榈酸则主要表现为抑制作用,但在很低浓度(25μmol/L)时也上调脂联素表达;脂联素基因表达与PPARγ基因表达相关。     

共轭亚油酸对饮食诱导肥胖大鼠脂代谢及相关基因表达的影响

目的:通过研究共轭亚油酸(CLA)对饮食诱导肥胖大鼠脂肪酸转移蛋白、酰基CoA合成酶基因表达的影响,探讨CLA抗糖尿病机制。方法:选雄性Wistar大鼠,随机分为对照组、高脂组、高脂+CLA组(每100g饲料含CLA分别为0.75、1.50、3.00g),每组动物10只,观察CLA对肥胖大鼠血清游离脂肪酸(FFA)、胰岛素、血糖水平的影响,并应用RT-PCR法检测脂肪酸转移蛋白(FATP)、酰基CoA合成酶(ACS)、过氧化物酶体增殖物活性受体γ(PPARγ)mRNA的表达水平。结果:高脂组大鼠血清FFA、胰岛素和血糖水平显著高于对照组,CLA可降低肥胖大鼠血清FFA、胰岛素、血糖水平,并且可增加肥胖大鼠脂肪组织FATP、ACS、PPARγmRNA的表达水平。结论:CLA可通过激活PPARγ上调FATP、ACS基因的表达,改善肥胖大鼠的胰岛素抵抗。     

肥胖儿童脂联素水平与肥胖相关生化指标的研究

目的 探讨肥胖儿体内脂联素水平的变化情况及脂联素与肥胖相关生化指标的关系.方法 采用配对设计,测定78对肥胖和对照儿童的血清脂联素,胰岛素,糖、脂代谢指标等.结果 儿童脂联素测定值为非正态分布.肥胖儿童脂联素水平低于正常对照儿童(7.60 μg/ml±4.58 μg/ml vs 10.08 μg/ml±5.36 μg/ml,P＜0.05;中位数P50 6.12 μg/ml vs 8.71μg/ml).肥胖组谷丙转氨酶、甘油三酯的异常率都明显高于对照组.正常体重儿童的脂联素水平与载脂蛋白A1呈正相关(r=0.32,P=0.012);与血糖呈负相关(r=-0.33,P=0.004).肥胖儿童脂联素水平与血糖呈正相关(r=0.23,P=0.041);与谷酰转肽酶(r=-0.25,P=0.049)、胰岛素(r=-0.31,P=0.006)、胰岛素敏感指数(r=-0.36,P=0.001)呈负相关.结论 肥胖儿童脂联素水平比正常儿童低,脂联素水平与机体肝细胞损伤,糖、脂代谢紊乱有一定的关系.     

Oral chromium picolinate improves carbohydrate and lipid metabolism and enhances skeletal muscle Glut-4 translocation in obese,hyperinsulinemic (JCR-LA corpulent) rats

Human studies suggest that chromium picolinate (CrPic) decreases insulin levels and improves glucose disposal in obese and type 2 diabetic populations. To evaluate whether CrPic may aid in treatment of the insulin resistance syndrome, we assessed its effects in JCR:LA-corpulent rats, a model of this syndrome. Male lean and obese hyperinsulinemic rats were randomly assigned to receive oral CrPic [80 microg/(kg. d); n = 5 or 6, respectively) in water or to control conditions (water, n = 5). After 3 mo, a 120-min intraperitoneal glucose tolerance test (IPGTT) and a 30-min insulin tolerance test were performed. Obese rats administered CrPic had significantly lower fasting insulin levels (1848 +/- 102 vs. 2688 +/- 234 pmol/L; P < 0.001; mean +/- SEM) and significantly improved glucose disappearance (P < 0.001) compared with obese controls. Glucose and insulin areas under the curve for IPGTT were significantly less for obese CrPic-treated rats than in obese controls (P < 0.001). Obese CrPic-treated rats had lower plasma total cholesterol (3.57 +/- 0.28 vs. 4.11 +/- 0.47 mmol/L, P < 0.05) and higher HDL cholesterol levels (1.92 +/- 0.09 vs. 1.37 +/- 0.36 mmol/L, P < 0.01) than obese controls. CrPic did not alter plasma glucose or cholesterol levels in lean rats. Total skeletal muscle glucose transporter (Glut)-4 did not differ among groups; however, CrPic significantly enhanced membrane-associated Glut-4 in obese rats after insulin stimulation. Thus, CrPic supplementation enhances insulin sensitivity and glucose disappearance, and improves lipids in male obese hyperinsulinemic JCR:LA-corpulent rats.     

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。     

The effects of obesity-associated insulin resistance on mRNA expression of peroxisome proliferator-activated receptor-gamma target genes, in dogs

Visceral adipose tissue and skeletal muscle have central roles in determining whole-body insulin sensitivity. The peroxisome proliferator-activated receptor-gamma (PPARgamma) is a potential mediator of insulin sensitivity. It can directly modulate the expression of genes that are involved in glucose and lipid metabolism, including GLUT4, lipoprotein lipase (LPL) and adipocytokines (leptin and adiponectin). In this study, we aimed to determine the effects of obesity-associated insulin resistance on mRNA expression of PPARgamma and its target genes. Dogs were studied when they were lean and at the end of an overfeeding period when they had reached a steady obese state. The use of a sensitive, real-time PCR assay allowed a relative quantification of mRNA expression for PPARgamma, LPL, GLUT4, leptin and adiponectin, in adipose tissue and skeletal muscle. In visceral adipose tissue and/or skeletal muscle, mRNA expression of PPARgamma, LPL and GLUT4 were at least 2-fold less in obese and insulin-resistant dogs compared with the same animals when they were lean and insulin-sensitive. The mRNA expression and plasma concentration of leptin was increased, whereas the plasma level and mRNA expression of adiponectin was decreased, by obesity. In adipose tissue, PPARgamma expression was correlated with leptin and adiponectin. These findings, in an original model of obesity induced by a prolonged period of overfeeding, showed that insulin resistance is associated with a decrease in PPARgamma mRNA expression that could dysregulate expression of several genes involved in glucose and lipid metabolism.     

职业接触镉对工人胰岛素水平的影响

目的研究镉对职业暴露人群胰岛素和血糖水平的影响。方法以我国中南地区某冶炼厂98名镉作业工人为职业接触对象,同时选取该厂职工医院未接触镉的健康医生作为对照。按照研究对象镉接触工龄及血镉、尿镉分组,调查了不同接触工龄组及不同血镉、尿镉组工人血清胰岛素水平的变化,同时检测机体血锌、尿锌水平的改变,并就血镉、血锌及血胰岛素等水平之间的相关关系进行分析。结果接触工龄20-年组血糖水平[(4．9±0．6)mmol／L]明显高于对照组[(4．6±0．5) mmol／L],差异有统计学意义(P<0．01)。接触工龄10～年组血清胰岛素水平[(8．58±4．91)μIU/ml]明显低于对照组[(11．57±5．42)μIU/ml],差异有统计学意义(P<0．05);且随血镉、尿镉水平的增加,血清胰岛素水平明显降低。接触工龄20-年者尿锌水平明显增高。相关分析显示,胰岛素与血镉、尿镉呈明显的负相关关系,血糖与胰岛素、C肽水平之间呈正相关关系。结论职业接触镉可以导致血清胰岛素水平的降低,可能影响血糖水平。     

Linoleic acid conjugation by human intestinal microorganisms is inhibited by glucose and other substrates in vitro and in gnotobiotic rats

The anticarcinogen conjugated linoleic acid (CLA) is a product of bacterial activity that isomerizes linoleic acid (LA) in the rumen of herbivores. Therefore, fatty dairy products in the human diet are enriched with CLA. Although bacteria capable of in vitro LA conjugation were detected in the human intestinal tract, CLA synthesis from dietary sunflower seed oil was not observed in gnotobiotic rats associated with these intestinal bacteria. The objective of the study was to investigate variables that affect LA conjugation. In vitro, LA conjugation was strongly inhibited by glucose and other substrates. Concentrations of 1.5 mmol glucose/L inhibited LA conjugation by 50%. Methyl-alpha-D-glucoside was a less effective inhibitor than glucose, and 2-deoxy-D-glucose did not inhibit LA conjugation at all. To analyze the concentration of carbohydrates in intestinal contents, the LA-conjugating bacterial mixed culture and human fecal microorganisms were introduced into germ-free rats. Samples of feces and cecum and colon contents of both groups exhibited in vitro LA-conjugating activity. Rats associated with human intestinal microorganisms contained 5.7 +/- 1. 3 mmol glucose/L in the cecal contents and 6.6 +/- 1.0 mmol glucose/L in the colonic contents. Rats associated with CLA-producing bacterial culture contained 3.4 +/- 1.3 mmol glucose/L in the cecal contents and 4.2 +/- 1.0 mmol glucose/L in the colonic contents. These values are within a range that may explain the observed inhibition of LA conjugation in vivo.     

Duration of improved muscle glucose uptake after acute exercise in obese Zucker rats

Skeletal muscle is insulin resistant in the obese Zucker rat. Endurance training reduces muscle insulin resistance, but the effects of a single acute exercise session on muscle insulin resistance in the obese Zucker rat are unknown. Therefore, insulin responsiveness of muscle glucose uptake was measured in 15-week-old obese rats either 1, 48, or 72 hours after two hours of intermittent exercise (30:30 min; work:rest). Hindlimbs of sedentary lean (LS) and obese (OS) rats and exercised obese (OE) rats were perfused after a 10-hour fast under both basal (0 mU x ml(-1)) and maximal (20 mU x ml(-1)) insulin concentrations to measure net glucose uptake. Insulin responsiveness of net glucose uptake was significantly reduced in OS compared to LS (8.5 +/- 1.6 vs 15.3 +/- 2.0 micromol x g(-1) x h(-1), respectively). Compared to OS, insulin responsiveness of net glucose uptake was significantly increased by 56% and 80% at 1 hour and 48 hours after acute exercise. However, 72 hours after acute exercise, the increased insulin responsiveness of net glucose uptake was no longer evident. These results indicate that improved responsiveness of muscle glucose uptake persists for at least 48 hours after two hours of acute intermittent exercise in 15-week-old obese Zucker rats.