Effect of Insulin on the Differential Expression of VLDL Receptor Isoforms of SGC7901 Cell and Its Biological Implication

This study examined the effect of insulin on the expression of very low density lipoprotein receptor (VLDLR) subtypes of SGC7901 cells and discussed its biological implication.In vitro, moderately or poorly-differentiated human gastric adenocarcinoma cell line SGC7901 was incubated with insulin for different lengths of time, and then the expression of protein and RNA level in VLDLR subtypes were detected by Western blotting and real-time PCR, respectively.The results showed that, at certain time interval, insulin could down-regulate expression of type Ⅰ VLDLR and up-regulate the expression of type Ⅱ VLDLR in SGC7901 cells, at both protein and RNA level.We are led to conclude that insulin serves as a regulator in maintaining the balance between glucose and lipid metabolism in vivo, possibly through its effect on the differential expression of VLDLR subtypes.

Silymarin in non alcoholic fatty liver disease

AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory parameters were assayed after 3 mo of a restricted diet and before silymarin treatment (twice a day orally). The brightness of liver echography texture (hepatorenal ratio brightness) was also defined at same time. These evaluations were repeated after 6 mo of treatment. RESULTS: Serum levels of some metabolic and anti-inflammatory data nonsignificantly lowered after 6 mo of silymarin. On the contrary, Steato test, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase were significantly (P < 0.001) reduced. Instead, the AST/ALT ratio unchanged. Finally, the hepatorenal brightness ratio, as an index of hepatic steatosis, significantly (P < 0.05) dropped. CONCLUSION: The obtained results indicate that silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.

Regulation and deregulation of cholesterol homeostasis: The liver as a metabolic "power station"

Cholesterol plays several structural and metabolic roles that are vital for human biology. It spreads along the entire plasma membrane of the cell, modulating fluidity and concentrating in specialized sphingolipid-rich domains called rafts and caveolae. Cholesterol is also a substrate for steroid hormones. However, too much cholesterol can lead to pathological pictures such as atherosclerosis, which is a consequence of the accumu- lation of cholesterol into the cells of the artery wall. The liver is considered to be the metabolic power station of mammalians, where cholesterol homeostasis relies on an intricate network of cellular processes whose deregulations can lead to several life-threatening pathologies, such as familial and age-related hypercholesterolemia. Cholesterol homeostasis maintenance is carried out by: biosynthesis, via 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity; uptake, through low density lipoprotein receptors (LDLr); lipoprotein release in the blood; storage by esterification; and degradation and conversion into bile acids. Both HMGR and LDLr are transcribed as a function of cellular sterol amount by a family of transcription factors called sterol regulatory element binding proteins that are responsible for the maintenance of cholesterol homeostasis through an intricate mechanism of regulation. Cholesterol obtained by hepatic de novo synthesis can be esterified and incorporated into apolipoprotein B-100-containing very low density lipoproteins, which are then secreted into the bloodstream for transport to peripheral tissues. Moreover, dietary cholesterol is transferred from the intestine to the liver by high density lipoproteins (HDLs); all HDL particles are internalized in the liver, interacting with the hepatic scavenger receptor (SR-B1). Here we provide an updated overview of liver cholesterol metabolism regulation and deregulation and the causes of cholesterol metabolism-related diseases. Moreover, current pharmacological treatment and novel hypocho-lesterolemic strategies will also be introduced.

Role of VLDL Receptor in the Process of Foam Cell Formation

The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP) and VLDLR were detected by semi quantitative RT PCR. The results demonstrated that VLDL, β VLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, ldl A7 VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.

Cholesterol metabolism in cholestatic liver disease and liver transplantation:From molecular mechanisms to clinical implications

The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that affect cholesterol metabolism, such as low-density-lipoprotein(LDL) receptor gene mutations that are associated with familial hypercholesterolemia. On the other hand, cholestatic liver disease often alters cholesterol metabolism. Cholestasis can lead to formation of lipoprotein X(Lp-X), which is frequently mistaken for LDL on routine clinical tests. In contrast to LDL, Lp-X is non-atherogenic, and failure to differentiate between the two can interfere with cardiovascular risk assessment, potentially leading to prescription of futile lipid-lowering therapy. Statins do not effectively lower Lp-X levels, and cholestasis may lead to accumulation of toxic levels of statins. Moreover, severe cholestasis results in poor micellar formation, which reduces cholesterol absorption, potentially impairing the cholesterol-lowering effect of ezetimibe. Apolipoprotein B-100 measurement can help distinguish between atherogenic and non-atherogenic hypercholesterolemia. Furthermore, routine serum cholesterol measurements alone cannot reflect cholesterol absorption and synthesis. Measurements of serum non-cholesterol sterol biomarkers- such as cholesterol precursor sterols, plant sterols, and cholestanol- may help with the comprehensive assessment of cholesterol metabolism. An adequate cholesterol supply is essential for liver-regenerative capacity. Low preoperative and perioperative serum cholesterol levels seem to predict mortality in liver cirrhosis and after liver transplantation. Thus, accurate lipid profile evaluation is highly important in liver disease and after liver transplantation.

Relationship between Insuline-like Growth Factor-I and Progesterone Secretion of Cultured Human Trophoblast Cells in Vitro

Objective To investigate the effect of insuline-like growth factor-Ⅰ （IGF-Ⅰ） on progesterone genesis and regulation. Methods Cytotrophoblast cells were collected by trypsin-collagenase digestion and percoll gradient centrifugation for primary culture. After stimulated with different concentrations（100 μg/ml, 10 μg/ml, 1 μg/ml, 0.1 μg/ml） of IGF-Ⅰ at the same time and with different duration（12 h,24 h,48 h, 72 h） of IGF-Ⅰ with the same concentration, progesterone levels in the media were measured by radioimmunoassay. Simultaneously, semiquantitative reverse transcriptase polymerase chain reaction （RT-PCR） was applied to determine the expression of low density lipoprotein receptor （LDLR） mRNA. Results Progesterone levels correlated positively with IGF-Ⅰ along with the IGF-Ⅰ concentration increasing, progesterone level began to increase at 12 h, and reached the climax at 48 h when cultured with 100 μg/L IGF-Ⅰ. The expression of LDLR mRNA was detectable in every group and accordant with variation of progesterone level. Conclusion Progesterone secretion has time- and dose-dependent effect on IGF-Ⅰ, and IGF-1 can up-regulate the expression of LDLR mRNA. IGF-Ⅰ may play an important role in promoting secretion of progesterone in trophoblast cells.

肝X受体α(LXRα)及三磷酸腺苷结合盒转运体A1(ABCA1)参与子痫前期发病的机理研究

目的探讨在子痫前期发病中LXRα和ABCA1的变化及二者与脂质代谢异常的关系。方法选取2019年10月至2023年6月在福建医科大学附属泉州第一医院妇产科分娩的子痫前期孕妇112例(子痫前期组),根据妊娠34周前是否诊断为子痫前期,将其分为早发组和晚发组;同期住院生产的70名正常孕产妇为正常对照组(正常组),采用生化方法测得血清中血脂水平(TG、TC、LDL及HDL);采用ELISA法检测2组患者血清中的LXRα与ABCA1蛋白表达水平;采用免疫组化及半定量PCR(RT-PCR)检测正常组及子痫前期组胎盘组织中LXRα与ABCA1的表达。分析LXRα和ABCA1表达与血脂异常的关系。结果子痫前期组TG、TC、LDL高于正常组,HDL低于正常组,差异均具有统计学意义(均P<0.05)。RT-PCR及免疫组化显示子痫前期组胎盘和血清的LXRα、ABCA1表达低于正常组(P<0.05)。胎盘上LXRαmRNA水平与LXRα蛋白表达水平呈正相关,差异具有统计学意义(P<0.05);两组患者血清ABCA1的表达水平与其胎盘上ABCA1蛋白浓度呈正相关,与血液循环中LDL的浓度水平呈负相关,与血液循环中HDL的浓度水平呈正相关,差异均有统计学意义(均P<0.05)。结论子痫前期妇女的血脂水平及血清中LXRα、ABCA1表达异常,且与病情严重程度相关;LXRα及ABCA1参与了子痫前期的血脂代谢异常的发生,可以作为临床上评判相关病程进展的依据。

槐角总黄酮对高脂血症大鼠降血脂及抗氧化能力的实验研究

目的:观察槐角总黄酮对高脂血症大鼠的降血脂及抗脂质过氧化作用.方法:用高脂饲料喂养大鼠4wk,建立实验性高脂血症大鼠模型,给予槐角总黄酮40,80,160mg/kg体质量,连续6wk,以绞股蓝总皂苷为阳性对照,检测血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)含量;测定血液黏度、肝脏丙二醛(MDA)含量、超氧化物歧化酶(SOD)活力及总抗氧化能力(T-AOC)的变化;逆转录-多聚酶链反应(RT-PCR)检测肝低密度脂蛋白受体(LDL-R)基因mRNA的表达.结果:槐角总黄酮能降低高脂血症大鼠血清TC,TG,LDL-C水平(P<0.05或P<0.01),升高HDL-C水平(P<0.05);降低全血黏度,使肝组织MDA水平降低,SOD及T-AOC活力升高,促进LDL-R基因mRNA的表达.结论:槐角总黄酮对高脂血症模型大鼠脂代谢紊乱具有较好的调节作用,可能是通过降低血液黏度、抗脂质过氧化,对肝LDL-R基因mRNA表达的调控来实现其降脂作用.

有氧运动对高胆固醇血症大鼠肝脏低密度脂蛋白受体活性调节的影响

本文研究了实验性高胆固醇血症大鼠肝脏低密度脂蛋白受体（ＬＤＬＲ）活性变化及有氧运动时ＬＤＬＲ活性调节的影响。发现，高脂（ＨＣ）组肝组织匀浆ＬＤＬＲ活性较正常对照（ＮＣ）组降低３７％（Ｐ＜０．０５），同时血清总胆固醇（ＴＣ）、低密度脂蛋白胆固醇（ＬＤＬＣ）及血清载脂蛋白Ｂ（ＡｐｏＢ）均显著高于ＮＣ组（Ｐ＜０．０１）；高脂＋运动（ＨＥ）组ＴＣ、ＬＤＬＣ及ＡｐｏＢ均明显低于ＨＣ组，而ＬＤＬＲ活性则较ＨＣ组增高２６％（Ｐ＜０．０５）。结果提示：（１）高胆固醇负荷时细胞可通过下行调节影响ＬＤＬＲ活性；（２）运动可能通过增加对细胞内胆固醇利用和降解，反馈作用于下行调节过程影响ＬＤＬＲ的合成，增加对ＬＤＬＣ摄取而显著改善血脂水平。

胰岛素抵抗在非酒精性脂肪肝发病中的作用

目的:探讨胰岛素抵抗(IR)在非酒精性脂肪肝(NAFL)大鼠脂肪肝模型中的作用机制.方法:大鼠随机分为空白对照组,脂肪肝模型对照组(模型+生理盐水组)和脂肪肝实验组(模型+罗格列酮组).其中脂肪肝模型对照组和脂肪肝实验组分别予生理盐水和马来酸罗格列酮干预治疗4wk.观察各组大鼠肝脏大体形态和组织学改变;检测空腹血糖(FPG),空腹血胰岛素水平(FINS),计算胰岛素抵抗指数(IRI);检测血浆ApoCⅡ、ApoCⅢ水平及血浆脂蛋白脂肪酶(LPL)、肝脂肪酶(HL)活性和大鼠肝组织ApoB-100mRNA的表达量.结果:治疗前,脂肪肝组大鼠(包括脂肪肝模型组和脂肪肝实验组)与空白对照组大鼠比较,肝脏组织学改变达到脂肪肝诊断标准,FPG、FINS明显升高(6.46mmol/L±0.75mmol/L,6.61mmol/L±0.45mmol/L vs5.48mmol/L±0.47mmol/L;78.82mU/L±11.13mU/L,78.48mU/L±12.94mU/Lvs40.90mU/L±7.76mU/L),IR也明显升高(22.48±2.81,22.98±3.47vs9.85±1.15),血浆ApoCⅡ水平降低、ApoCⅢ水平升高,LPL和HL酶活性均降低,肝组织ApoB-100mRNA的表达量降低.马来酸罗格列酮干预治疗4wk后,与脂肪肝模型对照组比较,脂肪肝实验组大鼠肝脏大体标本和组织学脂肪变性情况明显减轻,FPG,FINS降低(6.01mmol/L±0.56mmol/Lvs6.43mmol/L±0.47mmol/L,68.11mU/L±10.52mU/L vs82.48mU/L±15.20mU/L),IR降低(18.49±2.44vs23.39±3.16),血浆ApoCⅡ水平升高,ApoCⅢ水平降低,LPL和HL酶活性均增加,肝组织ApoB-100mRNA的表达量上升.结论:高脂肪高胆固醇饮食可以成功造成SD大鼠有IR的NAFL模型.通过改善脂肪肝大鼠的IR,可以改变血浆ApoCⅡ、ApoCⅢ水平来提高LPL和HL的酶活性,加速外周VLDL和TG的降解,促使肝组织ApoB-100mRNA的表达量上升,VLDL在肝脏合成加快,从而加快内源性TG的转运,减轻肝细胞脂肪浸润.

蒲黄对动脉粥样硬化大鼠肝脏低密度脂蛋白受体基因的影响

目的:探讨蒲黄对动脉粥样硬化(AS)大鼠模型低密度脂蛋白受体(LDLR)基因表达的影响。方法:实验采用一次性腹腔注射维生素D3加喂饲高脂饲料复制动脉粥样硬化动物模型。蒲黄混悬液低、中、高剂量按2g/kg、4g/kg、8g/kg体重3个剂量灌胃给药,每天一次,连续8周,同时喂饲高脂饲料,第6周、8周分别取肝组织,应用逆转录-聚合酶链反应(RT-PCR)技术检测低密度脂蛋白受体信使核糖核酸(mRNA)水平。结果:蒲黄高剂量组LDLR mRNA相对含量高于模型组,差异具有显著性;蒲黄中、低剂量组LDLR mRNA相对含量与模型组相比无差异。结论:高剂量的蒲黄可以调节脂质代谢紊乱,抗AS的形成,其机制与上调肝LDLR mRNA表达有关。

茵陈提取物对SD大鼠高脂血症模型血脂水平和肝脂肪变的影响

目的:观察茵陈提取物对高脂血症大鼠血脂和肝脏脂肪变性程度的影响。方法:用高脂饲料复制SD大鼠高脂血症模型,观察茵陈提取物对造模大鼠血清总胆固醇(TC)和甘油三酯(TG)水平的影响,对造模大鼠肝脏脂肪变性和MDA含量和SOD活性的影响。结果:茵陈提取物6,3,1.5g/kg能有效降低高脂血症大鼠血清中TC、TG、LDLC的含量,升高血清中HDLC的含量,并具有不同程度减轻高脂血症大鼠肝脂肪变,降低肝脏MDA含量,提高SOD活性的作用。结论:茵陈提取物通过调整血脂,对高脂血症大鼠模型具有良好的降脂和减轻肝脂肪变的作用。

重度脂肪肝与血脂异常的相关性研究

目的:探讨脂肪肝病情严重程度与血脂异常之间的相关性。方法:选取200例脂肪肝患者为脂肪肝组,其中轻度44例,中度102例,重度54例,选取肝脏无明显异常中老年体检者100例为对照组,检测两组血脂浓度。结果:总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)脂肪肝组分别为(5.57±1.38)、(3.13±2.18)、(0.92±0.26)、(3.71±0.93)mmol/L,对照组为(4.24±0.75)、(1.34±0.82)、(1.21±0.28)、(2.19±0.78)mmol/L,两组比较差异具有统计学意义(P<0.05);轻度脂肪肝患者为(4.98±0.95)、(1.43±0.99)、(1.15±0.26)、(2.43±0.80)mmol/L,中度为(5.63±1.14)、(2.32±1.81)、(1.06±0.25)、(3.15±0.91)mmol/L,重度为(6.14±1.56)、(3.48±2.35)、(0.87±0.28)、(3.82±0.94)mmol/L,不同分度脂肪肝患者之间比较差异具有统计学意义(P<0.05);非条件Logistic多因素回归分析结果显示TG是引起脂肪肝患病的独立危险因素(P<0.05),相关性分析脂肪肝病情严重程度与TC、TG、LDL-C浓度之间具有正相关(P<0.05),与HDL-C浓度之间具有弱负相关(P<0.05)。结论:脂肪肝病情严重程度与血脂水平异常之间具有密切相关性。

FGF-21通过上调肝脏LDL受体的表达降低血浆中LDL水平

目的成纤维细胞生长因子-21(FGF-21)可降低实验动物血浆中的低密度脂蛋白(LDL)的浓度,但其作用机制尚不清楚,本实验试图通过研究FGF-21对LDLR的调节作用揭示FGF-21调节血浆LDL浓度的机制。方法向谷氨酸钠(MSG)肥胖大鼠连续注射FGF-21蛋白40d后,检测其血浆中LDL的变化,并用荧光定量PCR的方法结合免疫荧光检测FGF-21对肝脏组织中LDLR mRNA及蛋白的影响。结果 MSG肥胖鼠经FGF-21处理,血浆内的LDL降低18%,其肝脏组织中LDLR mRNA含量提高9倍;HepG2细胞内的LDLR mRNA表达量随FGF-21处理时间增加而提高,且呈剂量依赖性;流式细胞仪检测显示,经FGF-21处理后HepG2细胞表面LDLR蛋白数量增加。结论 FGF-21通过增加肝细胞的LDLR表达量从而降低血浆中LDL浓度。

褐藻糖胶调节大鼠脂质代谢紊乱的作用

目的研究褐藻糖胶(FPS)调节大鼠脂质代谢紊乱的作用。方法通过建立大鼠高脂血症模型,观察FPS对大鼠血脂水平、脂代谢酶、粪便中脂类含量、胆汁代谢、肝脏低密度脂蛋白受体(LDL-R)mRNA的影响。结果FPS能抑制高脂血症大鼠血清甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-C)的浓度,升高高密度脂蛋白(HDL-C)的浓度和脂蛋白脂酶(LPL)、肝脂酶(HL)、卵磷脂胆固醇酰基转移酶(LCAT)的活性。FPS能增加粪便中胆固醇、甘油三酯、胆汁酸的含量,但对胆汁的分泌、胆汁中胆固醇和胆汁酸的浓度却无显著影响。逆转录聚合酶链反应(RT-PCR)实验显示,FPS能显著提高高脂血症大鼠肝脏LDL-R mRNA的表达水平。结论FPS可能通过抑制脂质(甘油三酯、胆固醇、胆汁酸)的吸收,激活脂代谢酶(LPL、HL、LCAT)的活性,促进肝脏低密度脂蛋白受体(LDL-R)mRNA的表达来调节脂质代谢紊乱。

氧化型低密度脂蛋白对3T3-L1脂肪细胞胆固醇流出的影响

目的:观察氧化型低密度脂蛋白(oxidized low-density lipoprotein,ox-LDL)干预是否刺激分化成熟的3T3-L1脂肪细胞胆固醇流出,并探讨其机制。方法:3T3-L1细胞促分化成熟后,给予不同浓度的ox-LDL(0～50μg/mL)干预8或24h;在以25μg/mL ox-LDL预处理脂肪细胞24h后,再以10μmol/L22(R)-羟基胆固醇干预24h,收集细胞,采用逆转录聚合酶链反应(reverse transcription polymer-ase chain reaction,RT-PCR)测定脂肪细胞三磷酸腺苷结合盒转运体A1(ATP binding cassette transporterA1,ABCA1),B族I型清道夫受体(scavenger receptor class B type I,SR-BI)和肝X受体α(liver X receptorα,LXRα)mRNA表达,采用液体闪烁计数器检测载脂蛋白A-I(apolipoprotein A-I,apoA-I)介导的细胞内胆固醇流出。结果:低浓度ox-LDL(12.5～25μg/mL)干预24h可增加脂肪细胞ABCA1,LXRα和SR-BImRNA的表达,并促进apoA-I介导的胆固醇流出,而高浓度(50μg/mL)则无此作用。将脂肪细胞用25μg/mL ox-LDL预处理24h,再用10μmol/L22(R)-羟基胆固醇干预细胞,ABCA1和LXRαmRNA表达均有显著增加(P<0.01),同时apoA-I介导的胆固醇流出增加,而SR-BImRNA表达无明显改变。结论:低浓度ox-LDL不仅可促进脂肪细胞LXRα-ABCA1-apoA-I通路,还可上调SR-BI表达,加速细胞内胆固醇流出。Ox-LDL这种新的作用不仅有利于维持脂肪细胞内胆固醇的动态平衡,还可能具有抗动脉粥样硬化作用。

驼奶对急性酒精肝损伤的辅助保护作用

目的探讨驼奶对小鼠急性酒精性肝损伤的辅助保护作用。方法60只雄性ICR小鼠随机分为5组,即500、1 000、3 000mg/kg b.wt.等3个剂量组、模型对照组和空白对照组。剂量组分别经口给予相应剂量的驼奶水溶液,模型对照组和空白对照组给予纯净水。连续灌胃30d后,空白对照组继续给予纯净水,其余各组于实验结束时1次给予50%的乙醇(14mL/kg b.wt.)灌胃,禁食16h,以建立小鼠急性肝损伤模型,分别检测各组肝匀浆中甘油三酯(TG)、还原型谷胱甘肽(GSH)、丙二醛(MDA)和血清中极低密度脂蛋白(VLDL)的含量,观察肝脏病变情况并比较。结果灌胃30d后,各剂量组与对照组小鼠体重差异均无统计学意义(P>0.05);模型对照组肝匀浆MDA和TG含量高于空白对照组,肝匀浆GSH和血清中的VLDL含量低于空白对照组(P值均<0.01),急性酒精肝损伤模型成功建立。各剂量组小鼠肝匀浆中MDA含量低于模型对照组,GSH含量高于模型对照组,其中500、1 000mg/kg b.wt.剂量组小鼠肝匀浆MDA、GSH含量,与模型对照组差异均有统计学意义(P值均<0.05);各剂量组小鼠肝匀浆中TG含量低于模型组,差异均有统计学意义(P值均<0.01);各剂量组血清VLDL含量高于模型对照组,3 000mg/kg b.wt.剂量组与模型对照组差异有统计学意义(P<0.05)。与模型对照组相比,各剂量组小鼠肝细胞脂肪变性不同程度减轻,其中1 000mg/kg b.wt.剂量组病变程度与模型对照组差异有统计学意义(P<0.05)。结论实验条件下,驼奶对小鼠急性酒精肝损伤有一定的辅助保护作用。

小鼠肝脏胰岛素受体的特异性敲除降低极低密度脂蛋白中三酰甘油分泌的研究

目的:建立肝组织特异性胰岛素受体急性缺失的动物模型,分析胰岛素信号缺失对三酰甘油代谢的影响。方法:在构建腺病毒时,利用Cre-LoxP系统机制,在Cre重组酶基因的上游插入肝组织特异性表达的白蛋白基因启动子。扩增纯化病毒,经小鼠尾静脉注射病毒14 d后,收集小鼠血浆,测定极低密度脂蛋白三酰甘油分泌速率,抽提肝脏脂质并用酶法检测脂质含量,用免疫印迹法分析胰岛素受体和脂代谢相关基因在肝脏内的表达。结果:成功构建了肝脏特异性胰岛素受体急性缺失动物模型。胰岛素信号缺失显著降低了小鼠肝脏的极低密度脂蛋白三酰甘油的分泌速度,同时也下调了肝脏脂肪酸合成相关基因和极低密度脂蛋白形成相关基因的表达。结论:肝脏胰岛素信号急性缺失降低极低密度脂蛋白中三酰甘油的分泌速度,这种变化可能和肝脏内脂肪酸的合成速度下降有关。

血管紧张素Ⅱ灌注在脂质肝损伤中的作用研究

目的:通过制备血管紧张素Ⅱ(AngⅡ)灌注模型,观察AngⅡ在脂质肝损伤中的作用及其可能的机制。方法:将C57BL/6小鼠随机分为对照组、AngⅡ灌注组及AngⅡ灌注加AngⅡ1型受体(AT1R)基因敲除组。采用HE、菲律宾、油红0染色以及胞内胆固醇定量测定法观察肝细胞内脂质沉积情况;免疫组化、蛋白质印迹法检测低密度脂蛋白受体(LDLR)、固醇调节元件结合蛋白2(SREBP-2)及其裂解激活蛋白(SCAP)表达水平。结果:AngⅡ刺激增加C57BL/6小鼠肝细胞内脂质沉积,且上调LDLR、SREBP-2和SCAP的表达。而AT1R基因敲除组C57BL/6小鼠肝细胞内脂质沉积明显减少,LDLR通路的相关蛋白表达也显著下调。结论:AngⅡ通过AT1R诱导LDLR负反馈调节失调,进而增加胆固醇内流、肝细胞内脂质过度沉积,介导脂质肝损伤的发生。

橄榄降脂胶囊对高脂血症大鼠血脂及其肝脏低密度脂蛋白受体基因表达的影响

目的:探讨中药橄榄降脂胶囊的降脂机制,为临床应用提供实验依据。方法:采用酶法检测大鼠血清总胆固醇(TC)、甘油三酯(TG);采用磷钨酸-镁沉淀法检测HDL-c、LDL-c,RT-PCR法测定肝低密度脂蛋白受体(LDLR)基因表达。结果:模型组大鼠TC、TG、LDL-c均显著高于正常组,HDL-c显著低于正常组(P<0.05)。与正常组比较,模型组大鼠肝LDLR mRNA表达降低,P<0.05。各治疗组肝LDLR mRNA表达升高,与模型组比较P<0.05。结论:橄榄降脂胶囊可能通过调节肝LDLR mRNA表达而纠正脂质代谢紊乱。