不同膳食脂肪酸对肝细胞SREBP-1c表达及脂代谢的影响

目的探讨不同膳食脂肪酸构成对肝细胞脂代谢及固醇调节元件结合蛋白-1c(sterol-regulatory elementarybinding protein-1c,SREBP-1c)表达的影响。方法以HepG2肝细胞为研究对象,分为空白对照组、二十碳五烯酸(EPA)组、棕榈酸(PA)组、EPA和亚油酸(LA)1∶1混合组、PA和油酸(OA)1∶1混合组,EPA、PA单独处理组终浓度为150μmol/L,混合处理组各组分浓度为75μmol/L,总浓度为150μmol/L,处理细胞24 h。采用油红O染色观察细胞内脂滴的变化,测定甘油三酯(TG)含量来评价细胞内脂质含量;采用RT-PCR、Western blot法检测SREBP-1c mRNA及蛋白的表达。结果 PA组、PA和OA 1∶1混合组SREBP-1c mRNA及蛋白的表达上调,EPA和LA 1∶1混合组、EPA组SREBP-1c mRNA及蛋白的表达下调,与对照组相比差异显著(P<0.05)。与对照组相比,EPA和LA 1∶1混合组、EPA组肝细胞内TG含量显著减少(P<0.05);PA和OA 1∶1混合组、PA组肝细胞内TG含量显著增加(P<0.05)。结论 PA、OA上调肝细胞SREBP-1c的表达并促进细胞内TG的合成,可能促进肝细胞脂肪变性;而EPA、LA下调肝细胞SREBP-1c的表达并显著降低肝细胞内TG含量,减轻肝细胞脂肪变性。     

肝X受体的激活对小鼠糖尿病肝脏脂肪酸合成酶表达的调节

目的 探讨肝X受体(LXR)对糖尿病肝脏脂肪酸合成酶(FAS)表达的影响及机制.方法 将16周龄、雄性、C57BL/6背景下瘦素受体基因缺陷的db/db小鼠和对照的db/m小鼠,分别予以LXR激动剂TO901317(TO)(3 mg·kg-1·d-1)或DMSO灌胃处理7 d;TO(10 μmol/L)刺激人肝癌细胞系HepG2细胞24 h.此外,HepG2细胞转染小鼠FAS启动子报告基因表达质粒,同时转染pcDNA3.1表达载体或LXR或活化型固醇调节元件结合蛋白(SREBP-1c)表达质粒12 h;采用免疫组织化学方法检测FAS蛋白在肝脏上的表达,实时荧光定量PCR和蛋白印迹方法分别在mRNA和蛋白水平检测FAS和SREBP-1的表达及TO对其表达的影响,荧光素酶报告基因方法检测LXR激动剂和SREBP-1c对小鼠FAS启动子活性的影响.结果 免疫组化结果显示FAS蛋白在肝脏广泛表达,主要位于肝细胞胞质内.TO可显著降低db/db小鼠空腹血糖水平[由(12.00±1.06)mmol/L下降到(7.73±0.69)mmool/L,P＜0.01]和糖化血红蛋白水平(由5.67%±0.10%下降到4.87%±0.08%,P＜0.01).db/db小鼠肝脏FAS mRNA水平明显高于db/m小鼠,约为5.5倍(P＜0.01);在蛋白水平,db/db小鼠肝脏上的FAS也明显高于db/m小鼠.TO处理可使db/m小鼠肝脏FAS mRNA表达升高约3.5倍(P＜0.05),可使db/db小鼠肝脏FAS mRNA升高约1.7倍(P＜0.05);TO处理可使db/m小鼠肝脏SREBP-1 mRNA升高约2.4倍(P＜0.05),使db/db小鼠肝脏SREBP-1 mRNA升高约2.1倍(P＜0.01).TO能够上调HepG2细胞FAS的mRNA表达水平,升高约1.9倍(P＜0.05);LXR的激活还能显著增加HepG2细胞中FAS基因启动子活性,约为对照组的1.5倍;过表达LXR或SREBP-1c也能增加HepG2细胞FAS基因启动子活性,分别为对照组的1.9倍和1.6倍(均P＜0.01).结论 LXR可能通过其本身的直接作用和SREBP-1C的间接作用上调肝脏FAS的表达,LXR可能介导了糖尿病肝脏的脂质生成过程.     

白藜芦醇通过激活PKA-PLIN2通路促进HepG2细胞脂滴脂解

目的 明确围脂滴蛋白2(perilipinin-2,PLIN2)在白藜芦醇(resveratrol,RSV)改善脂肪变性HepG2细胞脂滴代谢中的作用机制.方法 0.2 mmol/L棕榈酸处理HepG2细胞24 h,建立肝细胞脂肪变性模型.使用0、10、20、40、80 μmol/L RSV及转染PLIN2 siRNA或PKI过表达质粒后,再用40 μmol/L RSV干预24 h,油红O染色检测脂滴形成情况,酶法检测细胞内甘油三酯以及细胞外游离甘油含量,Western blot检测PLIN2蛋白表达,实时定量PCR检测PLIN2 mRNA表达.结果 RSV可以降低脂肪变性HepG2细胞脂滴蓄积程度,促进脂滴的脂解.RSV可以通过促进磷酸化增强PKA的活性,并呈浓度依赖性地上调PLIN2 mRNA和蛋白表达水平(P＜0.05).抑制PKA活性或下调PLIN2表达后,RSV促进脂肪变性HepG2细胞脂解的作用显著减弱(P＜0.05).结论 RSV通过激活PKA-PLIN2通路促进HepG2细胞脂滴脂解过程,从而可能改善非酒精性脂肪性肝病.     

Diet Rich in Saturated Fat Decreases the Ratio of Thromboxane/prostacyclin in Healthy Men

Objective To investigate the effect of dietary saturated fat (SFA) from animal sources on the urine excretion 11-dehydro thromboxane B_2 (TXB_2) and 6-keto prostaglandin F 1α (PGF 1α) in 27 healthy free-living male subjects aged 30 to 55 years. Methods It was a randomized crossover design. Each volunteer was randomly assigned to one of the two diets (high fat and low fat) for a period of 4 weeks, after which each subject resumed his usual diet for 2 weeks as a 'wash-out period', before being assigned to the other diet for an additional 4 weeks. Results Serum proportion of 20: 4n-6 was 5% lower in the high fat (6.2% of total fatty acid) than in the low fat diet (6.5% of total fatty acid), which was associated with a significantly decreased ratio of the urinary excretion 11-dehydro TXB_2 to 6-keto PGF 1α(P<0.05). However, there was no significant fall in the absolute urinary excretion of 11-dehydro TXB_2. Conclusions Diet rich in SFA from animal sources may influence TXA_2 formation via effect on tissu     

白藜芦醇通过上调脂肪变性HepG2细胞Sirt3表达改善线粒体功能

目的 探讨白藜芦醇(resveratrol,RSV)对脂肪变性肝细胞线粒体功能的影响,以及沉默信息调节因子3(sirtuin 3,Sirt3)在其中的重要作用.方法 用0.2 mmol/L棕榈酸(palmitic acid,PA)处理HepG2细胞24 h建立肝细胞脂肪变性模型,再用40 μmol/L RSV和/或50 μmol/L Sirt3抑制剂3-TYP处理24 h.实验分为对照组、PA组、PA+ RSV组、PA+ RSV+ 3-TYP组、PA+ 3-TYP组.用相关试剂盒检测甘油三酯(TG)含量、沉默调节蛋白3(sirtuin 3,Sirt3)活性、ATP合酶活性、ATP生成量以及线粒体基础呼吸率,使用DCFH-DA荧光探针检测细胞活性氧(reactive oxygen species,ROS)含量,Westernblot检测Sirt3蛋白表达.Sirt3 siRNA处理HepG2细胞后再用PA和/或RSV处理,分析ROS和甘油三酯含量.结果 相对于PA组,PA+RSV组HepG2细胞的甘油三酯、ROS含量明显降低(P＜0.05),ATP合酶活性、ATP生成量和基础呼吸率明显提高(P＜0.05).而3-TYP或Sirt3 siRNA处理后,RSV的上述作用被削弱(P＜0.05).结论 RSV通过上调脂肪变性肝细胞Sirt3的表达与活性而改善其线粒体功能.     

Exendin-4对胰岛素抵抗人肝癌HepG2细胞脂代谢相关因子基因表达的影响

目的：探讨Exendin-4（Ex-4）对胰岛素抵抗（IR）人肝癌HepG₂细胞脂代谢相关因子表达的影响,阐明Ex-4改善IR的作用。方法：选取处于对数生长期的人肝癌HepG₂细胞,采用高浓度胰岛素诱导HepG₂细胞制备IR模型（HepG₂-IR细胞）,再将其分为对照组（不含胰岛素的HepG₂细胞）、IR组（IR模型,即HepG₂-IR细胞）和Ex-4组（IR模型中加入10 nmol·L^-1 Ex-4）。采用葡萄糖氧化酶法（GOD-POD）检测细胞中葡萄糖消耗量,采用油红O染色观察细胞形态及胞内脂滴形成情况,应用甘油三酯（TG）试剂盒检测细胞中TG水平,采用荧光定量PCR（qRT-PCR）法检测细胞中乙酰辅酶A羧化酶（ACC）、脂肪酸合成酶（FAS）、固醇调节元件结合蛋白1c（SREBP-1c）和载脂蛋白B100（apoB100）等脂代谢相关因子mRNA表达水平。结果：HepG₂细胞建立IR模型后,与对照组比较,IR组HepG₂-IR细胞葡萄糖消耗量明显降低（P<0.01）;与IR组比较,Ex-4组HepG₂-IR细胞葡萄糖消耗量明显增加（P<0.05）。油红O染色法,与对照组比较,IR组细胞含脂率明显升高（P<0.05）;与IR组比较,Ex-4组细胞中含脂率明显降低（P<0.05）。与对照组比较,IR组细胞中TG水平明显升高（P<0.01）;与IR组比较,Ex-4组细胞中TG水平明显降低（P<0.05）。qRT-PCR检测,与对照组比较,IR组细胞中ACC、FAS和SREBP-1c mRNA表达水平明显升高（P<0.01）,apoB100mRNA表达水平明显降低（P<0.05）;与IR组比较,Ex-4组细胞中ACC、FAS和SREBP-1c mRNA表达水平降低（P<0.05）,apoB100 mRNA表达水平升高（P<0.01）。结论：Ex-4可通过调节人肝癌HepG₂细胞脂类代谢相关因子的表达进而改善IR。     

IL-17A基因敲除减轻脂多糖诱导的脂肪肝小鼠肝脏炎症性损伤及其机制

目的 在长程高脂膳食诱导的脂肪肝小鼠中,探讨白介素17A(interleukin 17A,IL-17A)基因缺陷对脂多糖(lipopolysaccharide,LPS)诱导的急性肝损伤的作用及其可能的机制.方法 利用IL-17A基因敲除小鼠构建脂肪肝急性损伤模型,通过检测血浆中谷丙转氨酶(alanine transaminase,ALT)和谷草转氨酶(aspartate transaminase,AST)评估肝脏损伤情况,通过检测血浆中3种主要炎症因子TNF-α、IL-1β以及IL-6评估机体炎症水平,通过肝脏病理形态观测肝脏组织炎症细胞浸润和肝细胞损伤情况.通过对肝脏组织表达mRNA进行转录组学分析,寻找IL-17A基因敲除在高脂膳食(high fat diet,HF)+LPS诱导的肝损伤中的发挥作用的相关分子信号机制.结果 在高脂膳食喂养辅之以一次性LPS刺激下,IL-17A基因敲除(gene knockout,KO)小鼠血浆中的ALT及AST水平显著降低(P＜0.05);KO小鼠血浆中炎症因子水平显著降低(P＜0.05),肝脏组织中浸润的炎症细胞显著减少(P＜0.05).肝脏转录组学分析结果显示,刺激后,KO小鼠下调的938个基因主要富集于氧化应激(P＜0.01)、过氧化氢代谢途径(P＜0.01)以及谷胱甘肽代谢途径(P＜0.01).Real-time PCR检测发现KO小鼠肝脏中与过氧化氢代谢相关的CAT、GPX1、IDH1、IDH2以及ME1基因的mRNA水平显著升高.同时,肝脏的氧化应激水平显著降低(P＜0.05).TUNEL检测进一步检测结果显示,KO小鼠肝脏凋亡细胞数量显著减少(P＜0.01).结论 IL-17A基因敲除可能通过促进过氧化氢代谢减轻LPS诱导的脂肪肝小鼠急性炎症性肝损伤.     

n-3多不饱和脂肪酸对大鼠非酒精性脂肪肝的改善作用

目的 探讨n-3多不饱和脂肪酸(n-3 PUFA)对高脂诱导的Wister大鼠非酒精性脂肪性肝(NAFLD)的改善作用.方法 Wister雄性大鼠30只,分为正常组、模型组、n-3 PUFA组.采用高脂喂养建立NAFLD模型,实验20周后,每组抽出7只大鼠检测血清及肝脏总胆固醇(TG)及三酰甘油(TC);其余3只大鼠肝脏苏木精-伊红(HE)染色;应用实时定量PCR(Real timeqPCR)及Western blot检测肝脏组织单核细胞趋化蛋白-1(MCP-1)、诱导型一氧化氮合酶(iNOS)、肿瘤坏死因子-α(TNF-α) mRNA及蛋白水平.结果 模型组大鼠血清及肝脏TG、TC水平明显高于对照组(P＜0.01),加入n-3 PUFA后血清及肝脏的TG、TC水平明显下降(P＜0.05).HE染色能明显观察到模型组大鼠肝细胞脂肪变性,而n-3 PUFA有明显改善效果.模型组大鼠炎症分子MCP-1、iNOS、TNF-α基因表达水平明显高于对照组(P＜0.05),而n-3 PUFA组与模型组比较,MCP-1、iNOS、TNF-α炎症分子的表达水平明显下降(P＜0.05).结论 高脂喂养能引起大鼠肝脏严重的脂肪变性及炎性反应,而n-3 PUFA起明显的改善作用.     

短链脂肪酸对HepG2细胞脂质堆积模型脂质代谢的影响

目的:揭示肠道菌群产物短链脂肪酸(Short-chain fatty acids, SCFAs)对HepG2细胞脂质堆积模型脂质代谢的影响。方法:通过油红O染色法观察油酸钠建立的HepG2细胞脂质堆积模型,使用不同浓度的SCFAs(乙酸、丙酸、正丁酸)干预HepG2细胞脂质堆积模型,MTT法检测HepG2细胞存活率;TC、TG试剂盒检测HepG2细胞脂质堆积模型中TC、TG含量;Western blot检测HepG2细胞AMPK、p-AMPK、ACC和p-ACC等蛋白的表达量。结果:随着三种SCFAs浓度的升高,HepG2细胞活性逐渐降低(P<0.05);SCFAs干预HepG2细胞脂质堆积模型后TC、TG含量降低(P<0.05),并抑制脂质堆积模型组细胞内AMPK、ACC的磷酸化表达。结论:SCFAs对HepG2细胞活性、HepG2细胞脂质堆积模型脂质代谢以及蛋白表达均有影响,不同浓度不同种类的SCFAs干预结果有差异。     

油酸在人肝癌HepG2细胞内转化生成9,10-二羟基硬脂酸

目的以人肝癌细胞株HepG2验证油酸转化生成9,10-二羟基硬脂酸（DHSA）途径。方法将HepG2细胞消化传代接种于24孔培养板,24h贴壁后分别加入含50μmol/L和100μmol/L油酸的无血清MEM培养液,培养24h和48h后测定细胞裂解液及上清液中DHSA和油酸（OA）的含量。结果添加50μmol/L和100μmol/L油酸培养24h后,HepG2细胞裂解液中DHSA浓度分别为（3.29±0.38）ng/ml和（6.33±1.99）ng/ml,无油酸对照组为（2.08±0.61）ng/ml;OA含量分别为（645.07±142.81）ng/ml和（1341.6±349.69）ng/ml,对照组为（359.68±12.06）ng/ml;上清液中DHSA和OA含量亦显著高于对照组。培养48h后,油酸组细胞裂解液中OA含量仍高于对照组,DHSA含量仅100μmol/L油酸组高于其他组;细胞上清液中OA含量仅100μmol/L油酸组高于对照组,DHSA含量各组间无显著差异。结论油酸可在HepG2细胞内代谢生成DHSA。     

Effect of high-fat diet on liver and placenta fatty infiltration in early onset preeclampsia-like mouse model

Background  Preeclampsia, especially early onset of preeclampsia (PE), is a common and serious disorder with high maternal and perinatal morbidity and mortality. Dietary factor is one of the most important factors which may affect the occurrence and development of the disease. The aim of this study is to investigate the effects of dietary factors on pathological changes of liver and placenta in preeclampsia-like mouse model by establishing the model at multiple stages of gestation.

Methods  Wild-type (WT) mice were injected subcutaneously with nitric oxide synthase (NOS) inhibitor L-arginine methyl ester (L-NAME, 50 mg×kg^–1×d^–1) to establish PE-like model (L-NAME group) at early-, mid-, and late- pregnant periods respectively; simultaneously, the control mice were injected with normal saline (NS group). All the groups were divided into subgroups, standard chow group (SC), and high-fat diet group (HF). ApoE^–/– pregnant mice served as a control group. Systolic blood pressure (SBP), urine protein, and histopathologic changes of placenta and liver in all groups were observed and statistically analyzed.

Results  In WT and apoE^–/– L-NAME subgroups, blood pressure and urine protein were significantly higher than those in all the gestational age matched NS groups (P <0.05). Compared to other groups, remarkable liver fatty infiltration and lipid storage in placenta were found in early- and mid-L-NAME subgroups in apoE^–/– mice (P <0.05), especially in the early- and mid-HF+L-NAME subgroups in apoE^–/– mice (P <0.05). More lipid storage droplets both in liver and placenta were found in ApoE^–/– mice than that of WT groups (P <0.05). Morphology histopathologic examination of placentas showed varying degrees of fibrinoid necrosis and villous interstitial edema in early- and mid-L-NAME both in HF and SC of apoE^–/– and WT subgroups compared to NS controls (P <0.05). But there was no significant difference between HF and SC subgroups (P >0.05), and no difference between apoE^–/–and WT groups (P >0.05).

Conclusions  Preeclampsia-like conditions could be induced by L-NAME in mice at different gestational stages. Both WT and apoE^–/– genotype mice with preeclampsia-like symptoms in early and mid stages of pregnancy presented lipid deposition in the placenta and hepatic fatty infiltration. To alter the environmental condition by feeding high-fat diet was harmful to the mother and the fetus. High-fat diet aggravated the impact of liver fatty infiltration at early and mid gestational stages especially in the apoE^–/– mouse model. These results further revealed the association between early-onset preeclampsia and the dysoxidation of fatty acids.

     

Diet Rich in Saturated Fat Decreases the Ratio of Thromboxane／prostacyclin in Healthy Men^1

Objective To investigate the effect of dietary saturated fat (SFA) from animal sources on the urine excretion ll-dehydro thromboxane B2 (TXB2) and 6-keto prostaglandin F la (PGF la) in 27healthy free-living male subjects aged 30 to 55 years.     

磷酸腺苷激活的蛋白激酶在慢性应激诱发小鼠非酒精性脂肪肝中的作用

目的 探讨磷酸腺苷激活的蛋白激酶(AMPK)及其激动剂5-氨基咪唑-4-甲酰胺核苷酸(AICAR)在慢性应激诱发小鼠非酒精性脂肪肝(NAFLD)中的作用.方法 建立小鼠慢性应激模型,设对照组、应激组、应激加AICAR给药组和AICAR给药组,每组6只.采用ELISA法检测小鼠血浆促炎性细胞因子(肿瘤坏死因子a,γ干扰素)浓度,采用自动生化分析仪检测小鼠血浆丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、总胆固醇、三酰甘油、游离脂肪酸的水平,采用苏木精-伊红染色和油红O染色检测肝细胞脂肪变性,采用蛋白质印迹法检测肝组织AMPK蛋白表达;然后用AICAR处理慢性应激小鼠并检测上述指标的变化.结果 慢性应激导致小鼠肝细胞脂肪变性,肝功能损害(ALT、AST水平升高,P＜0.01),血浆促炎性细胞因子浓度升高(P＜0.05),血浆游离脂肪酸水平升高(P＜0.01)以及肝组织AMPK蛋白表达降低(P＜0.01).AICAR改善了肝细胞脂肪变性,并缓解了上述指标的变化.结论 慢性应激可能通过AMPK信号通路诱发NAFLD,AMPK激动剂AICAR可缓解慢性应激导致的NAFLD.     

Expression of cyclooxygenase-2 and its pathogenic effects in nonalcoholic fatty liver disease

Objective:To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats,and to explore its possible mechanism.Methods:The rat NAFLD model was established by giving a fat-enriched diet.The blood samples were obtained form abdominal aorta and the levels of serum ALT,AST and IL-1,changes in the hepatic tissue 6-k-PGF1α TXB2 were measured.The expression level of COX-2 in rats livers were assayed by immunohistochemistry,RT-PCR and Western-blot.Results:Light microscope analysis revealed that hepatocytes were injured in the model group and slightly in the treatment group.The levels of serum TXB2 and IL-1 in the fatty liver rats were increased.Compared with the model group,the IL-1 and TXB2 increased significantly(P < 0.05),on the contrary,compared with the normal group,the hepatic tissue 6-Keto-prostagland decreased significantly in the model group(P < 0.05),the treatment group also increased but P > 0.05.There was no positive expression of COX-2 in hepatic tissue of normal rats.In the model group,there was positive expression of COX-2 antigen and the number of COX positive cells progressively increased at 4,8,12 wks.The intensity of expression of COX-2 had significantly increased(P < 0.05)and the intensity of COX-2 expression in the treated group decreased remarkably compared with the model group(P < 0.05).The expression of COX-2 mRNA and the level of COX-2 protein were significantly stronger in the liver of model rats compared with normal rats,and significantly weaker in treated rats,than in 8W and 12W model rats(P < 0.05).Conclusion:The increase of COX-2 expression in NAFLD is closely associated with the severity of liver inflammation and damage.COX-2 may play an important role in the progression of rat NAFLD,and the expression of COX-2 mRNA is downregulated by cyclooxygenase-2 inhibitor,which can depress the oxidative stress and control inflammatory response efficiently.     

线粒体靶向小分子IR-61改善小鼠非酒精性脂肪肝

目的 探讨线粒体靶向七甲川花菁类荧光小分子IR-61对小鼠非酒精性脂肪肝(non-alcoholic fatty liver disease,NAFLD)模型的治疗效果.方法 通过喂养高脂饲料建立NAFLD小鼠模型,腹腔注射磷酸缓冲盐溶液(phosphate buffer saline,PBS)或IR-61,治疗18周后,取肝脏组织切片HE常规染色,显微镜下观察,采用酶比色法检测肝脏和血清甘油三酯(triglyceride,TG)含量,Real-time PCR和Western blot法检测固醇调节元件结合蛋白1c(sterol regulatory element binding protein 1c,SREBP-1c)、乙酰辅酶A羧化酶1(acetyl-CoA carboxylase-1,ACC1)、过氧化物酶体增殖物激活受体α(peroxisome proliferator-activated receptor-α,PPARα)和肉毒碱棕榈酰转移酶-1(carnitine palmitoyltransferase-1,CPT1)的mRNA及蛋白表达水平.结果 IR-61可降低高脂诱导的小鼠肝脏TG含量增加,抑制SREBP-1c、ACC1过度表达;同时增加肝脏PPARα、CPT1的表达(P ＜0.05);IR-61可明显改善小鼠肝脏的脂肪沉积.结论 IR-61通过抑制高脂诱导的脂肪合成代谢过度增强,促进肝脏脂肪酸氧化,减少肝脏甘油三酯沉积,从而改善非酒精性脂肪肝.     

Differences between hepatic and biliary lipid metabolism and secretion in gene tically gallstone- susceptible and gallstone- resistant mice

目的：研究胆囊胆固醇结石易患鼠（C57L）和兔患鼠（AKR）肝胆脂质代谢和分泌的特征以及胆囊胆固醇结石形成状况。结果：无论结石餐前后C57L鼠肝内胆汁中脂质分泌率均明显高于AKR鼠,而肝内胆固醇含量却显低于AKR鼠;结石餐干预后C57L鼠肝内胆汁中胆固醇分泌率的增加幅度明显高于AKR鼠,胆囊胆固醇结石形成在C57L鼠,脂肪肝则出现在AKR鼠。结论：胆道胆固醇的高分泌是胆囊胆固醇结石形成的主要病理生理基础,结石基因决定了C57L鼠肝内胆汁中胆固醇的高分泌和胆囊胆固醇结石的易患性,成石胆汁形成在肝内胆管,先于胆囊结石的形成;肝内胆汁中胆固醇和胆酸的低分泌可能与AKR鼠脂肪肝的发生和胆囊结石的免患性有关。     

绞股蓝多糖含药血清对四氯化碳肝细胞损伤的保护作用

目的 研究绞股蓝多糖(gynostemma pentaphyllum makino polysaccharide,PGP)含药血清对四氯化碳(carbon tetrachloride,CCl4)诱导的肝细胞损伤保护作用。方法 采用中药血清学方法收集PGP含药血清,用CCl4诱导肝HepG2细胞损伤,设正常对照组、CCl4损伤组和不同浓度PGP含药血清保护组;细胞形态学观察细胞凋亡,MTT法检测细胞活力,生化法检测细胞培养上清液中丙氨酸氨基转移酶(alanine aminotransferase, ALT/GPT)、天门冬氨酸氨基转移酶(aspartate aminotransferase, AST/GOT)活性及western blot凝胶电泳检测细胞色素P450 2E1的表达。结果 各PGP含药血清保护组肝细胞损伤程度明显减轻;细胞存活率显著升高(P<0.05);上清液中ALT、AST活性显著降低(P<0.05);CYP 2E1表达量显著增加。以4~8mg·kg-1·d-1保护组效果最佳。结论 PGP含药血清对CCl4诱导的HepG2细胞损伤有明显保护作用,以4~8mg·kg-1·d-1含药血清作用最显著。     

SIRT1激动剂通过降低ACAT1表达抑制平滑肌泡沫细胞形成

目的 探讨沉默信息调节因子1 (silent mating type information regulation 2 homolog-1,SIRT1)对氧化型低密度脂蛋白(oxidized low density lipoprotein,ox-LDL)诱导的血管平滑肌细胞(vascularsmooth muscle cell,VSMC)泡沫化的作用和相关的分子机制.方法 用组织贴块法体外培养原代VSMC,用80μg/mL ox-LDL刺激VSMC诱导泡沫细胞形成.检测SIRT1在ox-LDL刺激不同时间(24、48、72 h)的表达变化.SIRT1的活性调控分别应用SIRT1激动剂(SRT1720,SRT,1μmol/L)和抑制剂(nicotinamide,Nic,100 μmoL/L)进行干预.干预24 h后采用Western blot检测VSMC过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,PPARγ)、酰基辅酶A:胆固醇酰基转移酶1(A-cholesterol acyhransferase 1,ACAT1)的蛋白表达,干预48 h后采用油红O染色检测细胞内脂质沉积和泡沫细胞形成情况.应用PPARγ激动剂(Rosiglitazone,RSG,50 μmol/L)和抑制剂(GW9662,10 μmol/L)调控PPARγ的表达,Western blot检测VSMC中ACAT1的表达.结果 ①ox-LDL诱导的VSMC泡沫细胞中,SIRT1蛋白表达在48 h降低约47％ (P ＜0.01);油红O染色显示,SRT可以抑制VSMC泡沫细胞形成,而Nic可逆转SRT的抑制作用;②ox-LDL诱导的VSMC泡沫细胞中ACAT1的表达显著增加[(2.77±0.70),P＜0.01],SIRT1激动剂SRT可显著抑制ACAT1的表达[(0.90±0.27),P＜0.01],而SIRT1抑制剂Nic可阻断这一作用,升高ACAT1的表达[(2.25±0.37),P＜0.05];③ox-LDL诱导的VSMC泡沫细胞中PPARγ的表达减少[(0.73±0.12),P＜0.05],SIRT1激动剂SRT可上调VSMC中PPARγ的表达[(0.98±0.16),P＜0.05],SIRT1抑制剂Nic抑制PPARγ的表达[(0.47 ±0.13),P＜0.01];④PPARγγ激动剂RSG可抑制ACAT1的表达[(0.73±0.09),P＜0.01],而PPARγ抑制剂GW9662则上调ACAT1表达[(1.68±0.09),P＜0.01].结论 SIRT1通过上调VSMC中PPARγ表达而抑制ACAT1表达,从而抑制ox-LDL诱导的VSMC泡沫样变.     

中国野生小鼠来源1号染色体替换系缺失突变的发掘及功能注释

目的 建立非酒精性脂肪性肝纤维化小鼠模型,观察其病变及炎症因子的表达情况.方法 20只雄性C57BL/6J小鼠随机分成对照组、非酒精性脂肪性肝纤维化模型组.对照组小鼠予以蛋氨酸-胆碱充足(MCS)饲料喂养,模型组小鼠予以蛋氨酸-胆碱缺乏(MCD)饲料喂养造模.于造模8周末处死小鼠.观察肝脏组织病理学变化,检测小鼠血清草氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、胆固醇(TC)、甘油三酯(TG)肿瘤坏死因子-α(TNF-∞、白细胞介素-6(IL-6)水平.结果 造模8周末,模型组小鼠体质量显著下降.肝组织病理学观察显示严重肝脂肪变,肝细胞水肿,可见点灶状坏死及淋巴细胞浸润,局灶见界面肝炎,汇管区扩大,纤维组织增生.模型组小鼠肝脏炎症活动度得分和纤维化得分均显著高于对照组(P＜0.01).模型组小鼠血清ALT、AST、TNF-α、IL-6与对照组比较显著升高,而TG和TC水平显著下降(P＜0.01).结论 小鼠经MCD饲料喂养8周出现严重肝脂肪变、肝纤维化和炎症因子高表达,表明成功诱导小鼠非酒精性脂肪性肝纤维化模型.该方法造模简单,成模快,存活率高,适合用于非酒精性脂肪性肝纤维化发病机制和药物干预等方面的研究.     

乙肝病毒X蛋白对油酸钠诱导HepG2细胞脂质沉积的影响

目的探讨乙肝病毒X蛋白(hepatitis B virus X protein,HBx)是否增加油酸钠诱导HepG2细胞的脂质沉积。方法将质粒pIRES2-eGFP-HBx瞬时转染入HepG2细胞中,建立表达HBx的细胞模型(HepG2-HBx);以转染空载体pIRES2-eGFP(HepG2-pIRES2)和HepG2细胞(HepG2)作对照。观察转染后绿色荧光蛋白(GFP)的表达;转染后16 h开始用油酸钠处理各组细胞24、48 h(分别命名为HBx/OA组、空/OA组、G2/OA组),细胞内甘油三酯(TG)含量测定及油红O染色了解细胞内脂质沉积情况;在油酸钠处理细胞24 h,RT-PCR法检测SREBP-1和LXRα的mRNA表达水平,Westernblot检测HBx、LXRα及FAS蛋白表达水平。结果转染后16 h HepG2-HBx细胞和HepG2-pIRES2细胞中开始有GFP的表达,提示转染成功;仅在HepG2-HBx细胞内有HBx表达,表明HepG2-HBx细胞模型构建成功。在相同油酸钠处理的条件下,HBx/OA组细胞内脂质含量和TG含量与对照组相比均明显增加(P<0.01)。在油酸钠处理细胞24 h,HBx/OA组细胞内LXRα、SREBP-1的mRNA表达量和LXRα、FAS蛋白表达量较对照组均明显增加(P<0.01/0.05)。结论 HBx通过上调HBx-LXRα-SREBP1/FAS通路脂质合成相关基因表达,可能增加HepG2-HBx细胞对外界脂代谢紊乱因素的易感性,从而增加油酸钠诱导HepG2细胞脂质沉积。