BSEP在高脂血症大鼠肝组织中表达的状况

目的:通过建立高脂血症大鼠模型,以胆盐输出泵(bile salt export pump,BSEP)为研究对象,探讨BSEP在高脂血症大鼠肝脏中的表达状况,初步思考其与高脂血症形成的相关性,为治疗高脂血症找到新的方向.方法:取♂Wistar大鼠60只,体质量145 g±7.5 g,随机分为2组,每组30只:普通饮食对照组(简称对照组)予以普通饮食、高脂饮食实验组(简称实验组)予以高脂饮食.喂食90 d,建立高脂血症模型,定期取血用自动生化仪检测胆固醇及胆汁酸含量,应用逆转录-聚合酶链反应(RT-polymerase chain reaction,RTP C R)技术检测两组模型肝脏组织的Bsep基因表达的强度,石蜡切片后用免疫组织化学SP(streptavidin-perosidase)法检测两组模型肝脏组织的BSEP表达的强度.结果:实验组胆固醇及胆汁酸含量明显高于对照组;电泳结果显示:实验中肝脏组织扩增产物都出现了内参β-actin基因的425 bp扩增带和Bsep基因的289 bp扩增带,实验组Bsep基因扩增带亮度强于对照组;免疫组织化学SP法结果显示,实验组Bsep表达阳性率为76.7%,对照组Bsep表达阳性率为12.5%,他们之间的差异有统计学意义(χ2=10.773,P<0.05).结论:实验组大鼠的Bsep基因的表达较对照组明显增加,提示我们可发展作用于Bsep的药物,为高脂血症及其相关疾病找到新的治疗方法.     

胆汁酸核受体FXR在非酒精性脂肪性肝病中的作用

非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)是以肝细胞脂肪变性和脂质沉积为特征,但无过量饮酒史、排外病毒感染和其他原因引起的肝脏疾病.NAFLD已成为一个全球关注的健康问题,其发病机制仍未阐明,尚无有效的药物治疗手段.法尼醇X受体(farnesoid X receptor,FXR)是需配体激活的转录因子,在胆汁酸、糖脂代谢中起着重要的调节作用.近年来研究显示FXR参与调控胰岛素抵抗(insulin resistance,I R)、脂质代谢异常、抑制肝星状细胞活化及炎症细胞渗入、促进肝内循环及肝细胞再生、延缓肝纤维化进程等NAFLD的重要环节.动物实验和临床研究也证实,FXR激动剂有延缓、治疗NAFLD的作用.提示FXR可能是NAFLD的潜在治疗靶点.目前,FXR应用于NAFLD仍存有争议.     

核受体在胆汁酸和胆固醇代谢中的作用

人体内多种核受体参与胆汁酸和胆固醇的代谢调节.近年来核受体调节胆汁酸及胆固醇代谢的研究已成为国内外研究的热点,其中尤以法尼酯X受体和肝X受体α作用最为重要,此文着重对该两种核受体的研究现状作一综述,对其他核受体作用作简要叙述.     

血清非高密度脂蛋白胆固醇在冠心病高脂血症中的诊断意义

高脂血症是冠状动脉粥样硬化发生、发展的主要危险因素。由于血脂分类繁多 ,不易被临床医师掌握。近年来 ,有学者 [1]提出了一个新的检测致动脉粥样硬化 ( AS)的脂蛋白指标—非高密度脂蛋白胆固醇( n HDLC) ,其能全面反映胆固醇的致 AS作用。本文从 1 999～ 2 0 0 0年干部查体中选取 2 62例冠心病稳定期合并不同类型高脂血症患者 ,与 2 1 0例正常健康者 ,分别测定 n HDLC进行比较 ,以探讨其临床意义。1　资料与方法1 .1　一般资料　本组 2 62例冠心病稳定期合并高脂血症患者 ,男性 1 46例 ,女性 1 0 9例 ,年龄 40～ 81岁 ,平均 5 9.87…     

从胆固醇代谢标志物视角分析高脂血症患者血脂异常的影响因素

目的分析胆固醇吸收与合成标志物及其它相关指标对高脂血症患者血脂成份的影响,探讨高脂血症患者胆固醇代谢特点。方法选取高脂血症患者(n=53)和健康对照者(n=50),常规检测肝肾功能及血脂水平,应用气相色谱法检测胆固醇吸收与合成标志物水平。结果高脂血症组总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDLC)显著高于健康对照组(P0.05);高脂血症组角鲨烯、7-烯胆烷醇的合成率均高于健康对照组(P0.05),而豆固醇吸收率低于健康对照组(P0.05)。多元线性逐步回归分析显示,高脂血症组影响TC的独立影响因素为LDLC和菜油固醇,影响TG的独立影响因素为脱氢胆固醇和LDLC,影响健康对照组TC和TG的独立影响因素均为LDLC和7-烯胆烷醇。结论高脂血症患者胆固醇代谢标志物特点是角鲨烯、7-烯胆烷醇合成率显著增高,植物固醇中豆固醇吸收率显著降低;高脂血症组影响TC和TG的独立影响因素除LDLC外,还与胆固醇合成标志物(脱氢胆固醇)、胆固醇吸收标志物(菜油固醇)有关。     

基因多态性参与胆固醇结石发病机制的研究进展

胆汁胆固醇过饱和及胆汁淤积是胆固醇结石的重要诱因。基因多态性通过影响胆固醇的转运及代谢,导致胆汁胆固醇过饱和、降低胆囊动力加重胆汁淤积,使个体对胆固醇结石的易感性增加。此文就近几年来对基因多态性在影响胆固醇结石发生方面的研究进展进行综述,以期进一步了解基因多态性在胆固醇结石发生中的作用,增进对胆固醇结石发病机制的了解,并为胆固醇结石的诊治提供新的思路。     

肝X受体在胆固醇代谢过程中的作用机制

胆固醇是细胞膜的组成成分,对维持机体代谢及正常的功能有着至关重要的作用。肝X受体(LXR)是肝脏中丰富表达的一种核受体,通过在肝细胞层面调控胆固醇及胆汁酸的合成、转化及转运来影响胆固醇代谢过程,在维持机体胆固醇稳态中发挥重要作用。另外,LXR能抑制食物中胆固醇在肠道的吸收,从而降低机体外源性胆固醇水平,从一定程度上降低机体总胆固醇水平,预防高胆固醇血症、胆结石等的形成。从肝脏和肠道两个层面对LXR调控胆固醇代谢的机制进行了总结。     

胆囊胆固醇结石病的遗传基础

胆囊胆固醇结石病的发生与胆汁胆固醇过饱和、成核缺陷以及胆囊收缩功能异常有关 ,同时受到遗传因素的影响。为进一步探索胆石病发病机制 ,复习近年来国内外胆石病的遗传基础研究取得的进展。     

复合膳食纤维对高胆固醇血症大鼠胆固醇代谢的长期作用

健康、断乳SD大鼠 84只 ,经高脂饲料诱导形成高脂血症模型后按体重及血胆固醇均衡的原则分为 7组 ,分别以基础饲料及高脂饲料作为对照组 ,其余 5组饲以不同水平的复合膳食纤维配方B(可溶性纤维 不可溶性纤维 =2 .0 ) ,实验期为 3个月 ,观察配方B对大鼠血浆胆固醇代谢的长期作用。结果表明 :与高脂组相比 ,高胆固醇血症大鼠的血总胆固醇、低密度脂蛋白胆固醇在不同水平的复合膳食纤维配方B组均显著降低 (P <0 .0 5 ) ,而高密度脂蛋白胆固醇水平及高密度脂蛋白胆固醇 低密度脂蛋白胆固醇比值显著升高 (P <0 .0 5 ) ;复合膳食纤维配方B在降低大鼠血总胆固醇浓度的作用上 ,存在明显的剂量反应关系。以上结果提示 :以燕麦麸、沙棘皮、瓜儿豆胶为主要原料研制成的复合膳食纤维确能长期有效地降低血浆胆固醇水平 ,可用于动脉粥样硬化和冠心病的防治。     

银杏叶提取物对实验性高脂血症血脂代谢的影响及抗氧化作用

目的 观察银杏提取物（GBE）对高脂血症大鼠血脂代谢的影响及抗氧化作用。方法 高脂饲料喂养21d，同时给大鼠灌胃GBE（50-100，200mg／kg）测定血清总胆固醇（TC）和甘油三酯（TG）、HDL-C（高密度脂蛋白-胆固醇）、LDL-C（低密度脂蛋白-胆固醇）活性，测定血清及肝组织中过氧化脂质（LPO）及超氧化物歧化酶（SOD）活性，并观察肝脏脂肪沉积情况。结果 GBE（100，200mg／kg）组均能明显降低血清TC、TG、LDL-C活性及血清和肝组织LPO，并能升高血清HDL-C及血清和肝组织SOD活性。病理检查可见肝脏脂肪沉积明显减轻。结论 GBE可能通过调整脂蛋白-胆固醇代谢，纠正自由基代谢紊乱，增强抗氧化酶活性等途径发挥调血脂及抗氧化作用。     

Age-related changes in the regulation of cholesterol metabolism in rats

Activities of the hepatic cholesterol synthetic system including initial steps of the pathway and cholesterol 7 alpha-hydroxylase were all lower in adult (8 to 9-month-old) rats than in young (5 week-old) rats. The extent of diurnal fluctuation of 3-hydroxy-3-methylglutaryl coenzyme A reductase was, however, apparently greater in adult animals. When the cholesterol-enriched diet was fed to rats for 1 day, the extent of the depression of the cholesterogenic enzymes was dependent on age of animals. The enzyme activities rapidly increased on refeeding a cholesterol-free diet after the cholesterol challenge. In young rats the activity of cholesterol 7 alpha-hydroxylase exhibited a pattern inverse to that of HMG-CoA reductase whereas in adult rats it increased continuously during the entire experimental period. Cholesterol and triglyceride accumulated in the liver of adult animals, and their response to dietary cholesterol also depended on the age of the animals. The results indicate a specific modification of the cholesterol homeostatic mechanism with age.     

Effects of pravastatin on cholesterol metabolism in Watanabe heritable hyperlipidemic rabbits.

Pravastatin, a competitive inhibitor of hydroxymethylglutaryl CoA reductase (HMG CoA reductase) is a potent hypocholesterolemic agent in humans as well as experimental animals, including the Watanabe heritable hyperlipidemic (WHHL) rabbit, lacking low density lipoprotein (LDL) receptor activity. We studied the effect of pravastatin on several aspects of cholesterol metabolism in WHHL rabbits. Cholesterol synthesis was measured by intraperitoneal injection of radioacetate and determination of its incorporation into the nonsaponifiable lipid fraction of liver, plasma, adrenal glands and gonads. A single dose of pravastatin (25 mg/kg) caused statistically significant inhibition of hepatic cholesterol synthesis at 2, 6, 12, and 24 hours following oral administration. By 48 hours, the inhibitory effect of the drug was no longer demonstrable. The pattern of radioactivity in the plasma was similar to that in the liver. The drug had no statistically significant effect on cholesterol synthesis in adrenal glands and gonads, suggesting a selective effect on the liver. Cholesterol absorption was studied after simultaneous oral administration of [3H] cholesterol and [14C] beta-sitosterol. Pravastatin, 50 mg/kg for 10 days had no effect on fecal excretion of the radiolabelled steroids over 4 days. At 24 hours the plasma level of [14C] cholesterol was 1/3 that of control in pravastatin treated animals (p < 0.05) but did not undergo an accelerated decline over 6 days. The activity of acyl CoA: cholesterol acyltransferase (ACAT) in intestinal mucosa and the concentration of hepatic cholesterol were similar in animals treated over one year with pravastatin 50 mg/kg/day or with placebo. Our data do not allow us to make definitive conclusions about the effect of pravastatin on cholesterol absorption but are compatible with the hypothesis that the drug inhibits the hepatic synthesis as well as the assembly of cholesterol into lipoproteins.     

Age-associated decrease in plasma cholesterol and changes in cholesterol metabolism in homozygous Watanabe heritable hyperlipidemic rabbits

We examined the cholesterol metabolism of homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model deficient in low-density lipoprotein (LDL) receptors, to clarify the mechanism of the age-associated decrease of plasma total cholesterol, one of the properties of WHHL rabbits. The rabbits were examined at several ages: after weaning at 3 months, at sexual maturation at 6 months, at 12 months, and at 24 months, equivalent to about 35 years of age in humans. Plasma total cholesterol, triglyceride, and phospholipid levels decreased with aging by about 45%. These reductions were mainly dependent on a decrease in the LDL fraction. In the liver microsomal fraction, although there were no age-related changes in the cholesterol concentration and cholesterol 7alpha-hydroxylase (C7H) activity, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity increased and acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity decreased with aging. The lipolytic activity varied with aging. The secretion rate of very-low-density lipoprotein (VLDL) cholesterol as determined by injection of Triton WR-1339 decreased significantly with aging, while the catabolic rate of VLDL cholesterol was about 2-fold higher in the oldest group versus the young groups. From these results, we conclude that the age-associated decrease in plasma cholesterol in WHHL rabbits is related not only to a decrease in the secretion rate of VLDL cholesterol but also to an increase in the catabolic rate.     

水仙子提取物对高脂血症大鼠血脂调节及肝脏保护的作用

目的 观察水仙子提取物对大鼠高脂血症的预防与治疗作用,及对肝脏脂肪性病变的保护作用.方法 水仙子经组织匀浆、过滤、离心后冷冻干燥,得到提取物干粉.(1)预防性实验:在建立高脂血症模型的同时给以提取物进行干预,实验结束后检测大鼠血脂水平及观察肝脏的病理变化;(2)治疗性实验:建立高脂血症模型后,以最优预防剂量进行干预,实验结束后观察上述指标外,并检测肝脏匀浆液中的超氧化物歧化酶(SOD)活力及丙二醛水平.结果 (1)预防性实验:不同剂量提取物均可较好的抑制大鼠血清中总胆固醇(TC)、甘油三酯(TG)和低密度载脂蛋白(LDL-C)的升高及高密度载脂蛋白(HDL-C)的下降,并有效地抑制肝脏的脂肪性病变;其中以高剂量组预防效果最为明显.高剂量组与阴性对照组比较,TC(3.23±0.01)mmol/L对(6.56±0.01)mmol/L、TG(2.33±0.01)mmol/L对(4.12±0.02)mmol/L、LDL-C(2.02±0.01)mmol/L对(3.91±0.02)mmol/L、HDL-C(0.98±0.01)mmol/L(0.76±0.01)mmol/L,差异均有统计学意义(P＜0.01);(2)治疗性实验:水仙子提取物可有效调节高脂血症大鼠血脂水平,治疗组与阴性对照组比较,TC(3.67±0.31)mmol/L对(6.33±0.52)mmol/L、TG(1.99±0.11)mmol/L对(4.08±0.24)mmol/L、LDL-C(1.57±0.12)mmol/L对(3.78±0.14)mmol/L、HDL-C(1.10±0.03)mmol/L对(0.77±0.02)mmol/L,均差异有统计学意义(P＜0.01);明显逆转肝脏的脂肪性病变,提高肝脏匀浆液中的SOD活力,降低丙二醛水平,高剂量组与阴性对照组比较SOD为(276.3±26.8)U/mg对(165.4±16.7)U/mg,丙二醛为(3.67±1.23)nmol/mg对(7.45±2.33)nmol/mg,差异均有统计学意义(P＜0.01).结论 水仙子提取物能有效防治大鼠高脂血症的发生和肝脏的脂肪变性,且有一定的抗氧化能力.     

氟中毒发生机制与骨代谢调控网络

近10多年来，骨的基础生物学有了长足发展，突出反映在一系列与骨代谢相关的细胞因子、转录因子的发现，对骨代谢调控网络有了更全面、更深入的认识。这些进步对地方性氟中毒（简称地氟病）发生机制的研究，从理论到方法学给予了有力的支持和有益的启示。[第一段]     

Plasma lipoproteins and cholesterol metabolism in spontaneously hyperlipemic rats

The aim of this study was to characterize the plasma lipoprotein pattern and some aspects of cholesterol metabolism in a line of hyperlipemic male rats. Plasma cholesterol and triglycerides were increased about 3-fold as compared to control animals (238 vs. 75 and 185 vs. 59 mg/dl respectively). The plasma lipoprotein distribution and the chemical composition of the isolated lipoproteins was unaffected. Plasma triglyceride production rate was increased (40%, P less than 0.01) and post-heparin lipoprotein lipase activity in plasma decreased (-28%, P less than 0.01) in the hyperlipemic rat. The activity of 3 enzymes involved in cholesterol metabolism (HMG-CoA reductase, cholesterol 7 alpha-hydroxylase, and acyl-CoA cholesterol-acyltransferase) did not differ from control values. 3H2O incorporation into digitonin-precipitable sterols, however, was significantly higher than in controls. This finding was due, in part, to an increased liver weight in the hyperlipemic animals. Furthermore kinetic data using 125I-LDL showed that the fractional catabolic rate of lipoprotein was within the normal range, while the synthetic rate of LDL protein was increased (0.67 vs. 0.3 mg/kg/h, P less than 0.01) in the hyperlipemic rat. These observations suggest that multiple metabolic defects underline the hyperlipemia observed in this animal model.     

Dietary fiber and cholesterol metabolism in rats fed a high cholesterol diet.

The effect of administering blackgram (Phaseolus mungo) fiber (isolated as neutral detergent residue) at the 30% dietary level has been studied with regard to lipid concentration in the tissues and that of biliary and fecal bile acids and sterols. Rats were fed a high fat-cholesterol diet and compared with those fed a cellulose diet. The results indicate that blackgram fiber significantly lowers cholesterol in both serum and aorta [11]. There was an increased concentration of biliary sterols and bile acids and increased fecal excretion of sterols and bile acids, each of these effects being significantly greater than those observed in the rats fed cellulose.     

Berberine decreases cholesterol levels in rats through multiple mechanisms,including inhibition of cholesterol absorption

Objective

The objective was to determine the mechanisms of action of berberine (BBR) on cholesterol homeostasis using in vivo and in vitro models.

Methods

Male Sprague–Dawley rats were fed the AIN-93G diet (normal control) or modified AIN-93G diet containing 28% fat, 2% cholesterol and 0.5% cholic acid with treatment of 0 (atherogenic control), 50, 100, and 150 mg/kg·d of BBR, respectively by gavaging in water for 8 weeks. Cholesterol absorption rate was measured with the dual stable isotope ratio method, and plasma lipids were determined using the enzymatic methods. Gene and protein expressions of Acyl-coenzyme A:cholesterol acyltransferase-2 were analyzed in vivo and in vitro. Cholesterol micellarization, uptake and permeability were determined in vitro.

Results

Rats on the atherogenic diet showed significantly hypercholesterolemic characteristics compared to normal control rats. Treatment with BBR in rats on the atherogenic diet reduced plasma total cholesterol and nonHDL cholesterol levels by 29%–33% and 31%–41%, respectively, with no significant differences being observed among the three doses. The fractional dietary cholesterol absorption rate was decreased by 40%–51%. Rats fed the atherogenic diet showed lower plasma triacylglycerol levels, and no changes were observed after the BBR treatment. BBR interfered with cholesterol micellarization, decreased cholesterol uptake by Caco-2 cells and permeability through Caco-2 monolayer. BBR also inhibited the gene and protein expressions of acyl-coenzyme A cholesterol acyltransferease-2 in the small intestine and Caco-2 cells.

Conclusion

BBR lowered blood cholesterol levels at least in part through inhibiting the intestinal absorption and further by interfering with intraluminal cholesterol micellarization and decreasing enterocyte cholesterol uptake and secretion.