双去甲氧基姜黄素对肥胖模型小鼠糖脂代谢的影响及机制

目的 研究双去甲氧基姜黄素(bisdemethoxycurcumin,BDMC)对高糖高脂饮食诱导的肥胖小鼠胰岛素抵抗、糖脂代谢紊乱的影响,并探讨其机制。方法 C57BL/6小鼠40只随机分为正常组(10只)和高糖高脂饮食组(30只),正常组小鼠给予常规饲料,其余小鼠饲喂高糖高脂饮食诱导肥胖,造模8周。造模成功后,高糖高脂饮食组小鼠随机分为模型组、BDMC低剂量组(20 mg·kg^-1)、BDMC高剂量组(40 mg·kg^-1),每组10只。分别按剂量灌胃给药,每日1次,每周5次,连续8周。给药结束后,检测小鼠体质量、肝脏及脂肪重量,观察肝脏病理改变及脂质堆积情况,监测小鼠血糖、血脂、血清胰岛素等生化指标,并考察BDMC对TRPV1、AMPK及下游胰岛素信号、糖脂代谢通路的影响。结果 与正常组相比,模型组小鼠体质量及脏器指数增加,肝脏出现明显的病理改变,脂质堆积严重,血清胰岛素、血糖、血脂参数(TC、TG、LDL-C)显著增高,HDL-C显著降低;肝损伤(ALT、AST)加重;肝脏组织中TRPV1、SREBP、FAS蛋白表达显著升高,p-IRS1、p-AMPK、GLUT4、p-ACC表达显著降低。与模型组相比,给予BDMC治疗后,肝脏脂质堆积减少,组织病理改变得到改善,血糖、血清胰岛素、TC、TG、LDL-C、ALT、AST显著降低(P<0.05),HDL-C显著升高,肝脏中p-IRS1、p-AMPK、GLUT4、p-ACC表达升高,TRPV1、SREBP、FAS表达显著降低(P<0.05)。结论 BDMC能改善胰岛素抵抗,调节糖脂代谢紊乱,治疗高糖高脂饮食诱导的肥胖,其作用可能与调节TRPV1和AMPK信号通路有关。     

胰岛素增敏剂罗格列酮升高血液中镍纹样蛋白水平

目的 探讨胰岛素增敏剂罗格列酮对血液中镍纹样蛋白（METRNL）水平的影响。方法 高脂饮食3个月诱导胰岛素抵抗的肥胖小鼠,给予罗格列酮治疗1个月,葡萄糖耐量实验检测罗格列酮对小鼠糖耐量的作用,酶联免疫吸附实验检测血清中METRNL水平,实时定量PCR检测肌肉、肝脏、白色脂肪、棕色脂肪、脑、脾脏、肾脏等组织中METRNL的表达,以及棕色脂肪中线粒体蛋白的表达。结果 罗格列酮治疗改善了高脂饮食动物的糖耐量,同时血液中METRNL浓度也显著增高;罗格列酮治疗增加了棕色脂肪和肾脏组织中METRNL的表达,对肌肉、肝脏、白色脂肪、脑、脾脏的METRNL表达没有影响;罗格列酮治疗增加了棕色脂肪线粒体相关蛋白的表达。结论 胰岛素增敏剂罗格利酮可能通过提高棕色脂肪和肾组织的METRNL表达升高血清METRNL水平,提示METRNL可能参与了罗格列酮对糖尿病的治疗作用。     

岩黄连总碱对代谢相关脂肪性肝病小鼠的治疗作用及分子机制研究

目的 研究岩黄连总碱对高糖高脂饮食诱导的代谢相关脂肪性肝病（MAFLD）小鼠的治疗作用。方法 随机取C57BL/6小鼠7只设置为对照组,喂以正常饲料;造模小鼠给予高脂饮食和高糖饮水（含20%果糖水）,连续喂养10周;将造模小鼠按体质量随机分为模型组、盐酸二甲双胍（阳性药,200 mg/kg）组和岩黄连总碱低、高剂量（25、100 mg/kg）组,继续饲以高脂高糖饮食,连续ig给药5周。记录小鼠体质量,取肝脏并拍照,测定小鼠肝脏质量,计算肝脏指数;应用血糖仪测定小鼠空腹血糖（FBG）及口服糖耐量（OGTT）;试剂盒法测定血清总胆固醇（TC）、三酰甘油（TG）、低密度脂蛋白胆固醇（LDL-C）、高密度脂蛋白胆固醇（HDL-C）及游离脂肪酸（NEFA）的水平;取肝组织进行HE染色、油红O染色和Masson染色;Western blotting检测肝组织中AMP依赖的蛋白激酶（AMPK）、p-AMPK、磷脂酰肌醇3-激酶（PI3K）、p-PI3K、蛋白激酶B （Akt）、p-Akt蛋白表达情况。结果 与对照组比较,模型组小鼠体质量、肝脏指数显著升高;给药后小鼠体质量及肝脏指数显著下降（P<0.05、0.01）。与模型组比较,岩黄连总碱显著降低小鼠的FBG及OGTT水平（P<0.01）;显著降低血清TC、TG、LDL-C及NEFA水平（P<0.01）;显著改善小鼠肝组织脂肪变及纤维化;显著上调MAFLD小鼠肝组织p-AMPK、p-PI3K、p-Akt蛋白水平（P<0.01）。结论 岩黄连总碱对MAFLD发挥显著治疗作用,其作用机制可能与通过激活AMPK/PI3K/Akt信号通路,减轻肝脏脂质沉积有关。     

白藜芦醇对高血脂模型小鼠的预防作用和对模型金黄地鼠的改善作用研究

目的:研究白藜芦醇对高血脂模型小鼠的预防作用和对模型金黄地鼠(以下简称地鼠)的改善作用。方法:以高脂高胆固醇饲料饲养诱导高血脂动物模型。将小鼠和地鼠均分为模型组和白藜芦醇低、中、高剂量组(小鼠给予40、80、160 mg/kg,地鼠给予25、50、100 mg/kg),每组10只,同时设立10只相应动物为正常对照组。除正常对照组动物喂食正常饲料和ig生理盐水外,其余小鼠在喂食高脂高胆固醇饲料的同时ig相应药物;其余地鼠先建模2周,成模后再ig相应药物,给药期间继续喂食高脂高胆固醇饲料。持续给药4周,每周检测各组小鼠和地鼠血清中总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)水平,给药4周后检测各组小鼠和地鼠血清中前蛋白转化酶枯草溶菌素9(PCSK9)mRNA及蛋白、微小RNA-27a(miRNA-27a)表达,以及小鼠肝组织中低密度脂蛋白受体(LDLR)蛋白表达。结果:与正常对照组比较,模型组小鼠从给药2周后开始血清中TC、LDL-C、PCSK9 mRNA及蛋白、miRNA-27a水平均明显升高(P<0.05),肝组织中LDLR蛋白水平明显降低(P<0.05);模型组地鼠给药期间血清中TC、LDLC、PCSK9 mRNA及蛋白、miRNA-27a水平均明显升高(P<0.05)。与模型组比较,各给药组小鼠和地鼠上述指标均明显改善(P<0.05),且与剂量呈正相关。结论:白藜芦醇对高血脂模型小鼠有预防作用,对模型地鼠有改善作用。其机制可能是通过下调血清中miRNA-27a表达与PCSK9蛋白表达,进而升高肝组织中LDLR蛋白水平,最终降低血清中LDL-C水平。     

烟酸通过下调PCSK9的表达促进HepG2细胞摄取LDL-C

目的探讨烟酸对HepG2细胞摄取及代谢LDL-C的影响,寻找烟酸改善血脂异常,减缓动脉粥样硬化进程的相关分子机制,为其临床用药提供指导。方法采用油红O染色观察细胞内脂质蓄积;酶法检测细胞内胆固醇含量;荧光流式检测细胞表面LDLR丰度分布;qPCR及Western blot检测LDLR、SREBP2以及PCSK9的mRNA及蛋白含量变化。结果经烟酸处理的HepG2细胞,油红O阳性细胞数及细胞内红染脂滴增多,细胞内TC、FC水平明显增高(P<0.05);LDLR mRNA含量无差异(P>0.05),而细胞膜表面LDLR分布丰度及细胞内LDLR的含量明显增加(P<0.05);烟酸对SREBP2的表达无影响,却能明显下调PCSK9的表达。结论烟酸可能通过下调PCSK9的表达,减少PCSK9成熟体蛋白含量,使得LDLR降解减少,进而增加LDLR含量,促进HepG2细胞摄取LDL-C。     

外泌体miRNA-222预警shRNA-PCSK9诱发脑Tau蛋白过度磷酸化

目的 探究血浆外泌体携带的微小RNA-222(microRNA-222,miRNA-222)能否作为shRNA-PCSK9 诱发认知障碍提供早期预警的标志物。方法 高脂饲料(high-fat diet,HFD)喂饲法制备高胆固醇血症小鼠模型。再将模型小鼠分为HFD-shRNA空白对照组和HFD-shRNA-PCSK9组。构建shRNA-PCSK9慢病毒,经静脉注入体内,实时荧光定量(realtime polymerase chain reaction,RT-PCR)法检测PCSK9 mRNA表达。免疫组织化学(immunohistochemistry,IHC)观察脑组织Tau蛋白和磷酸化。Western blotting检测Tau蛋白和P-Tau蛋白。ELISA法测定血清淀粉样蛋白Aβ1-42Ab水平。试剂盒分步提取血浆外泌体,负染电镜技术对外泌体形态进行鉴定,纳米颗粒跟踪分析技术测定外泌体粒径。RT-PCR技术检测血浆外泌体中携带的miRNA-222表达水平。结果 HFD喂饲13周制备模型组小鼠,血清总胆固醇(total cholesterol,TC)、低密度脂蛋白(low density lipoprotein,LDL-C)含量显著升高,同时,模型组小鼠脑组织内PCSK9 mRNA表达明显升高。经shRNA-PCSK9慢病毒干扰后,PCSK9 mRNA表达抑制,同时IHC观察到shRNA-PCSK9诱发了脑组织Tau蛋白的异常表达和过度磷酸化,表明已发生神经纤维缠结的病理改变。然而,此时血清Aβ1-42Ab尚未明显升高,尚未具备诊断认知障碍的意义。将血浆外泌体中的miRNA提取,RT-PCR结果显示,HFD-shRNA-PCSK9组外泌体中携带的miRNA-222表达量与HFD-shRNA空白对照组相比显著降低。结论 血浆外泌体携带的miRNA-222可以作为shRNA-PCSK9 诱发认知障碍提供早期预警的标志物。     

雷公藤多苷片对高脂小鼠血脂的影响

目的 研究雷公藤多苷片对高脂小鼠血脂的影响。方法 采用高血脂小鼠模型,通过小鼠尾静脉注射不同剂量（0.5,1.0,1.5 mg·kg^-1·d^-1）雷公藤多苷,测定不同时间段小鼠体质量和血清总胆固醇（total cholesterol,TC）、甘油三酯（totaltriglyceride,TG）、高密度脂蛋白胆固醇（high density lipoprotein cholesterol,HDL-C）、低密度脂蛋白胆固醇（low densitylipoprotein cholesterol,LDL-C）的含量及卵磷脂胆固醇酰基转移酶（lecithin cholesterol acyltransferase,LCAT）、肝脂酶（hepatic lipase,HL）和脂蛋白脂酶（lipoprotein lipase,LPL）的活性,研究雷公藤多苷对小鼠体质量、血脂代谢、动脉粥样硬化指数、肝脏LCAT水平等的影响。结果 给予高脂饲料后小鼠体质量和血脂显著升高（P<0.01）,动脉粥样硬化指数显著升高（P<0.01）,抗动脉粥样硬化指数显著下降（P<0.01）。注射雷公藤多苷能显著降低高血脂模型小鼠血清TC、TG和LDL-C,同时显著降低高脂饮食所导致的动脉粥样硬化指数升高。此外,雷公藤多苷片能显著提高血清LCAT水平和HL、LPL的活性。结论 雷公藤多苷片具有一定的降血脂功能,并能有效降低动脉粥样硬化的发生几率。     

6种2型糖尿病动物模型中生化和病理改变的比较

目的 比较6种常见2型糖尿病动物模型的生化指标和胰岛、肝脏的组织病理学改变。方法 大鼠、小鼠各32只,随机分为8组：大鼠对照组、大鼠高脂高糖+四氧嘧啶组、大鼠高脂高糖+链脲佐菌素组、ZDF大鼠组、小鼠对照组、db/db小鼠组、ob/ob小鼠组和KK-ay小鼠组。制备2型糖尿病模型：高脂高糖+四氧嘧啶组和高脂高糖+链脲佐菌素组,喂饲高脂高糖饲料6周后,分别ip 1次150 mg/kg剂量的四氧嘧啶和30 mg/kg的链脲佐菌素,ZDF大鼠饲喂Purina#5008饲料6周;C57BL、db/db和ob/ob小鼠普通饲料、KK-ay小鼠高脂料喂养8周。每周测定体质量;腹主动脉取血,全自动生化分析仪测定血清空腹血糖（FBG）、胆固醇（TC）、三酰甘油（TG）、低密度脂蛋白胆固醇（LDL）和高密度脂蛋白胆固醇（HDL）,Elisa法检测血清中空腹胰岛素（FINS）水平。剖取胰腺、肝脏进行HE染色,于光学显微镜下观察组织病理学变化。结果 与对照组比较,高脂高糖+四氧嘧啶及高脂高糖+链脲佐菌素组大鼠体质量增长幅度更大;ZDF大鼠组体质量缓慢降低;血脂、血糖和胰岛素测定结果显示,与大鼠对照组比较,高脂高糖+四氧嘧啶组和高脂高糖+链脲佐菌素组FBG、TC、TG均显著升高（P<0.01）,FINS显著降低（P<0.01）;ZDF大鼠组FBG、TC、TG、HDL和FINS均显著升高（P<0.05、0.01）。与小鼠对照组比较,db/db、ob/ob、KK-ay小鼠组FBG、TC、TG、HDL、LDL和FINS均显著升高（P<0.05、0.01）（其中db/db小鼠LDL除外）。组织病理学检查结果显示,与大鼠对照组比较,高脂高糖+四氧嘧啶组与高脂高糖+链脲佐菌素组胰岛萎缩,体积减小,数量减少,分布稀疏,形态极不规则,胰岛细胞空泡样变,数目减少,β细胞坏死凋亡;肝脏可见不同程度的肝细胞空泡变性;ZDF大鼠组胰岛萎缩,体积减小,形状不规则,边界不清,炎细胞浸润,纤维组织增生,岛内β细胞凋亡,形态不清,排列紊乱;轻微至轻度肝细胞空泡变性。与小鼠对照组比较,db/db、ob/ob、KK-ay小鼠组均可见胰岛增生、肥大,岛内β细胞核增多、密集,胞浆减少,排列紊乱;中至重度肝细胞空泡变性。结论 6种大鼠2型糖尿病模型糖脂代谢紊乱,可致肝脏空泡变性和胰岛的病理改变。其中3种大鼠2型糖尿病模型可致胰岛的退行性病变,3种小鼠2型糖尿病早期模型可致胰岛的代偿性增生肥大的病变。     

PCSK9及IDOL在姜黄素促进HepG2细胞摄取LDL-C中的作用

目的从分子水平探讨姜黄素的降脂机制,为姜黄素作为降脂药物的临床开发提供科学依据。方法本研究运用油红O染色、酶法测定细胞内胆固醇含量,荧光染色检测细胞胆固醇摄取,RT-Q-PCR及Western blot检测姜黄素对HepG2细胞内胆固醇代谢相关因子在RNA和蛋白水平的表达。结果姜黄素组的HepG2细胞内红色脂滴明显增多,且TC及FC含量增高。Di I标记LDL,姜黄素组HepG2细胞橙红色荧光高于对照组。姜黄素能升高SREBP2和LDLR的mRNA和蛋白水平的表达;降低PCSK9蛋白成熟体及IDOL蛋白表达。结论姜黄素可能通过下调PCSK9及IDOL的表达,进而减少LDLR降解,促进HepG2细胞摄取LDL-C。     

Berberine inhibits dyslipidemia in C57BL/6 mice with lipopolysaccharide induced inflammation

BackgroundInhibiting the action of proprotein convertase subtilisin/kexin type 9 (PCSK9) on the low-density lipoprotein receptor (LDLR) has emerged as a novel therapeutic target for hypercholesterolemia. Here we investigated the effect of berberine, natural plant extracts, on PCSK9-LDLR pathway in C57BL/6 mice with lipopolysaccharide (LPS) induced inflammation.MethodsForty female mice were divided into four groups (n = 10): control, LPS (5 mg/kg), LPS + berberine 10 (5 mg/kg LPS plus 10 mg/kg berberine), and LPS + berberine 30 (5 mg/kg LPS plus 30 mg/kg berberine). Changes in the levels of blood lipids [total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C)]; pro-inflammatory cytokines [interferon-γ (IFNγ), tumor necrosis factor α (TNFα), and interleukin-1α (IL-1α)], 8-isoprostane, hepatic expressions of PCSK9 and LDLR were determined.ResultsBerberine pretreatment reduced the expression of hepatic PCSK9, decreased the plasma TC, TG, LDL-C, IFNγ, TNFα, IL-1α, and 8-isoprostane concentrations; increased HDL-C level and LDLR expression in mice.ConclusionThe present results suggest that berberine inhibits dyslipidemia in C57BL/6 mice with LPS induced inflammation through regulating PCSK9-LDLR pathway.     

MG132, a proteasome inhibitor,enhances LDL uptake in HepG2 cells in vitro by regulating LDLR and PCSK9 expression

Aim:

Expression of liver low-density lipoprotein receptor (LDLR), a determinant regulator in cholesterol homeostasis, is tightly controlled at multiple levels. The aim of this study was to examine whether proteasome inhibition could affect LDLR expression and LDL uptake in liver cells in vitro.

Methods:

HepG2 cells were examined. Real-time PCR and Western blot analysis were used to determine the mRNA and protein levels, respectively. DiI-LDL uptake assay was used to quantify the LDLR function. Luciferase assay system was used to detect the activity of proprotein convertase subtilisin/kexin type 9 (PCSK9, a major protein mediating LDLR degradation) promoter. Specific siRNAs were used to verify the involvement of PCSK9.

Results:

Treatment of HepG2 cells with the specific proteasome inhibitor MG132 (0.03–3 μmol/L) dose-dependently increased LDLR mRNA and protein levels, as well as LDL uptake. Short-term treatment with MG132 (0.3 μmol/L, up to 8 h) significantly increased both LDLR mRNA and protein levels in HepG2 cells, which was blocked by the specific PKC inhibitors GF 109203X, Gö 6983 or staurosporine. In contrast, a longer treatment with MG132 (0.3 μmol/L, 24 h) did not change LDLR mRNA, but markedly increased LDLR protein by reducing PCSK9-mediated lysosome LDLR degradation. Furthermore, MG132 time-dependently suppressed PCSK9 expression in the HepG2 cells through a SREBP-1c related pathway. Combined treatment with MG132 (0.3 μmol/L) and pravastatin (5 μmol/L) strongly promoted LDLR expression and LDL uptake in HepG2 cells, and blocked the upregulation of PCSK9 caused by pravastatin alone.

Conclusion:

Inhibition of proteasome by MG132 in HepG2 cells plays dual roles in LDLR and PCSK9 expression, and exerts a beneficial effect on cholesterol homeostasis.     

Berberine--a novel approach to cholesterol lowering

Although low-density lipoprotein (LDL)-cholesterol lowering with the statins reduces the mortality and morbidity associated with coronary artery disease, considerable mortality and morbidity remains. Berberine upregulates the LDL receptor (LDLR) by a mechanism distinct from that of the statins, which involves stabilising the LDLR mRNA. In hamsters fed a high-fat and high-cholesterol diet for 2 weeks, the oral administration of berberine 100 mg/kg for 10 days reduced total serum cholesterol from approximately 4.8 to 2.7 mmol/l, and LDL-cholesterol from approximately 2.5 to 1.4 mmol/l. In subjects with hypercholesterolaemia, berberine hydrochloride (0.5 g b.i.d. for 3 months) reduced LDL-cholesterol (from 3.2 to 2.4 mmol/l) without any effect on high-density lipoprotein-cholesterol. Berberine also caused a reduction in triglyceride levels from 2.3 to 1.5 mmol/l. As berberine and statins both upregulate LDLR, their lipid-lowering profiles are similar. Thus, this mechanism is unlikely to make berberine an attractive alternative to statins for lipid lowering in most circumstances. However, the other effects of berberine (antihypertensive, inotropic and class III antiarrhythmic properties) may make it a useful agent in the treatment of cardiovascular disease.     

Berberine – a novel approach to cholesterol lowering

Although low-density lipoprotein (LDL)-cholesterol lowering with the statins reduces the mortality and morbidity associated with coronary artery disease, considerable mortality and morbidity remains. Berberine upregulates the LDL receptor (LDLR) by a mechanism distinct from that of the statins, which involves stabilising the LDLR mRNA. In hamsters fed a high-fat and high-cholesterol diet for 2 weeks, the oral administration of berberine 100 mg/kg for 10 days reduced total serum cholesterol from ～ 4.8 to 2.7 mmol/l, and LDL-cholesterol from ～ 2.5 to 1.4 mmol/l. In subjects with hypercholesterolaemia, berberine hydrochloride (0.5 g b.i.d. for 3 months) reduced LDL-cholesterol (from 3.2 to 2.4 mmol/l) without any effect on high-density lipoprotein-cholesterol. Berberine also caused a reduction in triglyceride levels from 2.3 to 1.5 mmol/l. As berberine and statins both upregulate LDLR, their lipid-lowering profiles are similar. Thus, this mechanism is unlikely to make berberine an attractive alternative to statins for lipid lowering in most circumstances. However, the other effects of berberine (antihypertensive, inotropic and class III antiarrhythmic properties) may make it a useful agent in the treatment of cardiovascular disease.     

硫化氢对动脉粥样硬化胆固醇代谢的调节作用

目的观察H2S对动脉粥样硬化(AS)胆固醇代谢的影响,并探究其作用机制。方法用高脂饲料结合维生素D3的方法建立AS大鼠模型,并给与腹腔注射NaHS 56μmol·kg-1.d-1,持续12周。检测血脂水平及肝胆固醇含量。HepG2细胞给与NaHS 100μmol·L-16 h后,用RT-PCR方法检测羟甲基戊二酰辅酶A还原酶(HMGCoA reductase)和低密度脂蛋白受体(LDLR)mRNA表达。结果 NaHS组血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-Ch)和低密度脂蛋白胆固醇(LDL-Ch)均较模型组降低,肝胆固醇含量下降。NaHS使HepG2细胞HMGCoA Re-ductase mRNA表达下降,LDLR mRNA表达增加。结论H2S对AS胆固醇代谢具有调节作用,能下调肝HMGCoAReductase,使胆固醇合成下降;上调肝脏LDLR表达,降低血清总胆固醇水平。     

小檗碱对高果糖饲养诱导大鼠胰岛素抵抗和肝脏TNF-α表达的影响

目的研究小檗碱对高果糖饲养诱导胰岛素抵抗大鼠的作用。方法高果糖饲料喂养SD大鼠6wk后,分为3组,模型组,小檗碱组(187.5mg.kg-1.d-1灌服)、二甲双胍组(184mg.kg-1.d-1灌服)作为对照,继续高果糖饮食。实验同时设立正常对照组,普通饮食喂养。4wk后处死大鼠;测定血糖、血清胰岛素、胰岛素抵抗指数及血脂的变化,用RT-PCR方法观察肝脏TNF-αmRNA的表达。结果模型组胰岛素、胰岛素抵抗指数、游离脂肪酸(free fatty acids,FFA)及甘油三酯(triglycerides,TG)水平均明显升高;肝脏TNF-αmRNA的表达与正常对照组比较明显升高。小檗碱降低了胰岛素抵抗大鼠的血糖、血清胰岛素、胰岛素抵抗指数、TG、FFA及TNF-αmRNA的表达。二甲双胍降低了大鼠的血糖、血清胰岛素、胰岛素抵抗指数及TG。结论小檗碱可以改善胰岛素抵抗,其机制可能包括抑制肝脏TNF-αmR-NA的表达与改善脂代谢紊乱。     

Inhibition of PCSK9 as a novel strategy for the treatment of hypercholesterolemia

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role controlling the levels of low-density lipoprotein (LDL) particles that circulate in the bloodstream. Several gain-of-function and loss-of-function mutations in the PCSK9 gene, which occur naturally, have been identified and linked to hypercholesterolemia and hypocholesterolemia, respectively. Studies have demonstrated that PCSK9 acts mainly by enhancing degradation of the LDL receptor (LDLR) protein in the liver. Inactivation of PCSK9 in mice reduces plasma cholesterol levels primarily by increasing hepatic expression of LDLR protein and thereby accelerating clearance of circulating LDL cholesterol. Since the loss of a functional PCSK9 in human is not associated with apparent deleterious effects, this protease is becoming an attractive target for lowering plasma LDL cholesterol levels either alone or in combination with statins.     

黄连及小蘖碱降血糖作用的研究

实验证明,黄连水煎剂可以降低正常小鼠血糖,黄连的主要成分小蘖碱可以降低正常小鼠、四氧嘧啶糖尿病小鼠和自发性糖尿病KK小鼠的血糖。给正常小鼠腹腔注射葡萄糖或肾上腺素可以引起血糖升高,小蘖碱可以对抗这两种作用。给小蘖碱后,可以改善KK小鼠的葡萄糖耐量。此外,小蘖碱可以降低喂高胆固醇乳剂小鼠的血清胆固醇水平,在体外可以抑制家兔血小板聚集。     

Ameliorative effect of berberine on endothelial dysfunction in diabetic rats induced by high-fat diet and streptozotocin

Berberine can improve insulin resistance, lower blood glucose, and regulate lipid metabolism disorders which cause endothelial dysfunction, leading to vascular complications of type 2 diabetes mellitus. The aim of the present study was to investigate the effects of berberine on endothelial dysfunction of aortas in type 2 diabetes mellitus rats and its mechanism. Wistar rats were randomly divided into four groups: diabetic rats, control rats, diabetic rats treated with berberine (100 mg/kg), and control rats treated with berberine. The serum fasting blood glucose, insulin, total cholesterol, triglyceride and nitric oxide (NO) levels were tested. Acetylcholine-induced endothelium-dependent relaxation and sodium nitroprusside induced endothelium-independent relaxation were measured in aortas for estimating endothelial function. The expression of endothelial nitric oxide synthase (eNOS) mRNA was measured by RT-PCR, and the protein expressions of eNOS and NADPH oxidase (NOX4) were analyzed by western blot. The results showed that berberine significantly decreased fasting blood glucose, and triglyceride levels in diabetic rats. Berberine also improved endothelium-dependent vasorelaxation impaired in aorta. The expressions of eNOS mRNA and protein were significantly increased, while NOX4 protein expression was decreased in aortas from diabetic rats with berberine treatment. Moreover, serum NO levels were elevated after berberine treatment. In conclusion, berberine restores diabetic endothelial dysfunction through enhanced NO bioavailability by up-regulating eNOS expression and down-regulating expression of NADPH oxidase.