氢杨梅素改善高脂饮食诱导的肥胖小鼠肝脏脂肪沉积及机制（英文）

有文献报道, SIRT1-AMPK信号通路可能在DHM改善肝脏细胞甘油三酯蓄积、胰岛素抵抗等作用中发挥作用。为此,本课题拟进一步观察DHM对高脂饮食诱导的肥胖小鼠肝脏脂肪沉积的影响,并探讨其可能机制。C57BL/6J小鼠采用普通饲料和高脂饲料喂养,同时分别用或不用低剂量(125 mg/kg)或高剂量(250 mg/kg)的DHM处理16周。实验期间,每两周检测体重一次。16周后,眼眶静脉取血并处死动物,同时取肩胛下、附睾与腹股沟的脂肪并用电子秤进行称重,并记录脂肪重量。全自动生化分析仪检测:血清甘油三酯(triglyceride,TG)、血清总胆固醇(totalcholesterol,TC)、血清高密度脂蛋白(high-densitylipoprotein,HDL)、血清低密度脂蛋白(low-densitylipoprotein,LDL)。取肝脏甲醛固定、HE和油红O染色检测肝脏脂肪沉积情况;比色法检测肝脏MDA和SOD含量; Realtime PCR检测相关指标的基因表达:IL-6、IL-8、TNF-α、乙酰辅酶A羧化酶(acetyl-Co A carboxylase, ACC)、固...     

Osthole improves fat milk-induced fatty liver in rats: modulation of hepatic PPAR-alpha/gamma-mediated lipogenic gene expression

The objectives of this study were to determine the therapeutic effect of osthole, an active constituent isolated from Cnidium monnieri (L.) Cusson (Apiaceae), in hyperlipidemic fatty liver (HFL) rats and investigate the possible mechanism of the osthole treatment. The HFL rat model was established by feeding Sprague-Dawley rats with fat milk for 6 weeks. The experimental rats were then treated with a dose of osthole of 5 - 20 mg/kg for 6 weeks. After the treatment, total cholesterol (TC) and triglycerides (TG) in serum and hepatic tissue, as well as the coefficient of hepatic weight were measured. The results showed that the TC and TG in both serum and hepatic tissue and the coefficient of hepatic weight in the osthole-treated rats were lower as compared to those in the experimental group, respectively (P < 0.05 or P < 0.01). Moreover, as compared to the control group, the osthole treatment increased the PPARalpha/gamma mRNA expression by 58.0 - 84.0 % and 20.4 - 77.4 %, respectively. The related target genes for mRNA expression were also increased by osthole-treatment, e. g., 53.4 - 93.2 % for CYP7A, 21.1 - 63.2 % for L-FABP and 34.1 - 57.3 % for FATP4, while the DGAT mRNA expression was decreased by 26.0 - 44.4 %. The therapeutic effect of osthole was further confirmed by histological evaluation of the liver showing a dramatically decreased lipid accumulation and improved ultrastructure of hepatocytes. In conclusion, osthole exerts therapeutic effects on fat milk-induced fatty liver in rats, by regulating mRNA expression of the target genes of CYP7A, DGAT, L-FABP and FATP4 via increasing the PPARalpha/gamma mRNA expression.     

Effect of oxymatrine on lipid metabolism regulated genes in liver of fat-induced insulin resistance in ApoE-/-mice北大核心CSCD

Aim To investigate the effect of oxymatrine on lipid metabolism regulated genes in liver in fat-induced insulin resistance in ApoE-/- mice. Methods Seventeen C57BL/6J male mice were selected in normal control group. Sixty-eight ApoE-/- mice with high fat diet for 16 weeks, were randomly divided into model group, oxymatrine low, middle and high dose groups. Then they were gavaged for 8 weeks. Body weight and general biochemical indicators were determined in mice. The mRNA and protein expression levels of LPL, FAT/CD36, CPT1, UCP2, SREBP-1 c, FAS and ACC were examined by real-time PCR and Western blot in the liver. Results Compared with model group, oxymatrine reduced body weight (BW) , fasting blood glucose (FBG), cholesterol (TC) , triglyceride (TG) , free fatty acids (FFA), fasting plasma insulin (FINS) and insulin resistance index(HOMA-IR) (P < 0. 05) , while improved glucose infusion rate (GIR) . Oxymatrine down-regulated the mRNA and protein expression of LPL, FAT/CD36, UCP2, SREBP-1c, FAS and ACC(P <0. 05) ,and up-regulated the mRNA and protein expression of CPT1 in varying degrees (P < 0. 05). Conclusion Oxymatrine can regulate the expression of lipid metabolism regulated genes in liver and improve insulin resistance in ApoE-/- mice induced by high fat diet.     

Overweight induced by chronic risperidone exposure is correlated with overexpression of the SREBP-1c and FAS genes in mouse liver

Weight gain and metabolic disturbances, such as dyslipidemia and hyperglycaemia, are common side effects of most antipsychotic drugs, including risperidone. The aim of this study was to investigate the effects of chronic treatment with risperidone on body weight, fat accumulation, liver weight, and hepatic expression of key genes involved in lipid metabolism in female mice. We also addressed the mechanism of risperidone induction of metabolic side effects by exploring its effect on lipid and cholesterol metabolism in primary cultures of rat hepatocytes. Eleven?weeks of treatment with long-acting risperidone (12.5?mpk/week) resulted in a significant weight gain associated with an increase of liver and adipose tissue weight. These effects were positively correlated with hepatic mRNA induction of two key genes involved in lipogenesis: sterol regulatory element binding protein-1c (SREBP-1c) and fatty acid synthase (FAS). Furthermore, in line with these in vivo results, risperidone elicited significant inductions of SREBP-1 maturation and FAS mRNA expression in primary cultures of rat hepatocytes associated with an increase of free fatty acid, triacylglycerol, and phospholipid synthesis as assessed by acetate incorporation. The current investigations underscore the usefulness of a mouse model to study the weight gain observed with risperidone treatment in humans. This study shows that risperidone induces similar effects in the liver (in vivo) and in hepatocyte cell cultures (in vitro) on the expression of key genes and/or proteins that control lipid metabolism. This suggests that risperidone could alter lipid metabolism in the liver and induce weight gain in a way that is partly independent of its action on the central nervous system.     

豚鼠高脂血症模型LDL-C代谢紊乱的机制研究

目的建立豚鼠高胆固醇血症模型,并对形成机制进行探讨。方法高脂饲料诱导法建立豚鼠高胆固醇血症模型,分别于造模1、2、4周检测血清脂质的动态变化;检测肝脏脂质;酶联免疫分析法测定血清ox-LDL浓度;实时荧光定量PCR法检测肝脏CYP7A1(cholesterol 7a-hydroxylaseA1)、肝脏法尼酯X受体(hepatic farnesoid X receptor,FXR)、肝X受体α(liver X receptor,LXRα)、HMG-CoA还原酶mRNA的相对表达;Western blot法检测肝脏LDL-R的蛋白表达情况。结果豚鼠经高脂饲料诱导1周后,模型组与对照组比较血清TC、LDL-C即发生升高,随造模时间延长,血脂一直维持在较高水平。造模4周后模型组血清ox-LDL、sd-LDL浓度,肝脏TC水平比正常组升高。肝脏HMG-CoA还原酶表达下调,LDL-R蛋白表达量明显高于正常组。值得注意的是豚鼠肝脏法尼酯X受体(FXR)表达明显上调,且肝X受体α(LXRα)表达也明显上调,但二者激活水平相当,最终未改变肝脏CYP7A1mRNA的表达水平。结论高脂诱导豚鼠形成高胆固醇血症主要与外源性胆固醇和低密度脂蛋白的清除发生障碍有关。     

Garlic oil alleviated ethanol-induced fat accumulation via modulation of SREBP-1, PPAR-α, and CYP2E1

Garlic oil (GO) has been shown to partially attenuate ethanol-induced fatty liver, but the underlying mechanisms remain unclear. The current study was designed to evaluate the protective effects of GO against ethanol-induced steatosis in vitro and in vivo, and to explore potential mechanisms by investigating the sterol regulatory element binding protein-1c (SREBP-1c), peroxisome proliferators-activated receptor-α (PPAR-α), cytochrome P4502E1 (CYP2E1), and etc. In the in vitro study, human normal cell LO2 was exposed to 100 mM ethanol in the presence or absence of GO for 24 h. We found that ethanol increased the protein levels of n-SREBP-1c and CYP2E1, but decreased the protein levels of PPAR-α, which was significantly attenuated by GO co-treatment. In the in vivo study, male Kun-Ming mice were pretreated with single dose of GO (50-200 mg/kg body weight) at 2 h before ethanol (4.8 g/kg body weight) exposure. The changes of n-SREBP-1c, PPAR-α and CYP2E1 were paralleled well to those of in vitro study. Furthermore, GO significantly reduced the protein levels of fatty acid synthase (FAS), and suppressed ethanol-induced hepatic mitochondrial dysfunction. These results suggested that GO had the potential to ameliorate alcoholic steatosis which might be related to its modulation on SREBP-1c, PPAR-α, and CYP2E1.     

Alleviative effects of resveratrol on nonalcoholic fatty liver disease are associated with up regulation of hepatic low density lipoprotein receptor and scavenger receptor class B type I gene expressions in rats

Lipid metabolic disorders are widely considered to be one of the most critical and basic link in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). The aim of this study was to illustrate the alleviation function of resveratrol (Res) on NAFLD and the roles of hepatic fatty acid synthase (FAS), low density lipoprotein receptor (LDLr), scavenger receptor class B type I (SR-BI), and thyroid hormone receptor β1 (TRβ1), which are the key molecules involved in lipid metabolism. Adult male Wistar rats were fed a normal diet or high fat/sucrose diet (HFS) with or without resveratrol for 13 weeks. HFS induced NAFLD formation and increased the lipids concentrations in serum and livers of rats, while noticeable improvement has been reached by Res intervention. Moreover, Res protected against HFS-induced decrease in hepatic LDLr and SR-BI mRNA and protein expressions, whereas TRβ1 expressions were impervious with/without Res. Unexpectedly, hepatic FAS gene expressions were markedly diminished in NAFLD rats and were gradually increased by treatment with Res. These data indicate that the alleviative effects of Res on NAFLD are associated with up regulation of hepatic LDLr and SR-BI gene expressions, which provide new insights into the pharmacological targets of Res in the prevention of NAFLD.     

表没食子儿茶素没食子酸酯对大鼠高脂性脂肪肝的治疗作用研究

目的研究表没食子儿茶素没食子酸酯(EGCG)对大鼠高脂性脂肪肝的治疗作用。方法以脂肪乳剂灌胃的方法建立高脂性脂肪肝大鼠模型,造模成功后将高脂性脂肪肝大鼠随机分为EGCG(10、20和40 mg.kg-1)3个剂量治疗组、非诺贝特治疗组(20 mg.kg-1)以及模型对照组。分别观察EGCG对高脂性脂肪肝大鼠的肝重和肝脏系数、血脂水平、肝功能指标以及抗氧化能力的影响;光镜和电镜观察大鼠肝组织脂质变性程度和超微结构的改变。结果EGCG10、20、40 mg.kg-1治疗6 wk后,高脂性脂肪肝大鼠肝重和肝脏系数、血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白-胆固醇(LDL-C)、游离脂肪酸(FFA)、谷丙转氨酶(ALT)和谷草转氨酶(AST)水平以及肝组织中TC和TG含量明显降低(P<0.05或P<0.01),血清高密度脂蛋白-胆固醇(HDL-C)水平明显升高(P<0.05),肝组织中超氧化物歧化酶(SOD)的活性明显升高(P<0.05或P<0.01),同时肝组织中丙二醛(MDA)水平明显降低(P<0.05或P<0.01),并且具有一定的剂量依赖趋势。光镜和电镜观察结果表明,给予EGCG的大鼠肝组织脂质变性程度和肝细胞超微结构改变明显减轻(P<0.01)。结论EGCG 10、20、40mg.kg-1治疗6 wk后,对高脂性脂肪肝大鼠具有较好的治疗作用,其作用机制可能与降低血脂水平和增强机体的抗氧化能力有关。     

Adenosine A₁ receptors do not play a major role in the regulation of lipogenic gene expression in hepatocytes

Activation of adenosine A? receptors was reported to promote fatty acid synthesis in AML-12 cells, by increasing the expression of SREBP-(1c) (sterol regulatory binding protein 1c) and FAS (fatty acid synthase). Since these findings have important therapeutic implications for the discovery of adenosine A? receptor agonists, further studies were undertaken to determine the expression and functional relevance of adenosine A? receptor in the liver. To that end, we used two classes of distinct adenosine A? receptor agonists: CPA (N?-cyclopentyl-adenosine), a full agonist and GS-9667 (2-{6-[((1R,2R)-2-hydroxycyclopentyl)-amino]purin-9-yl}(4S,5S,2R,3R)-5-[(2-fluorophenylthio)methyl]-oxolane-3,4-diol), a partial agonist. Treatment of AML-12 cells, HepG2 cells and primary human hepatocytes with either CPA or GS-9667 did not increase the gene expression of SREBP-(1c) or FAS. Furthermore, in AML-12 and HepG2 cells, CPA did not antagonize forskolin-stimulated cAMP production, a characteristic of adenosine A? receptor activation, indicating that these cells lack adenosine A? receptor function. Consistent with this finding, adenosine A? receptor gene expression was found to be very low and adenosine A? receptor protein levels were hardly detectable by radioligand binding assays in hepatic cell lines such as AML-12 and HepG2 as well as in both mouse and human liver tissues. Finally, acute treatment with adenosine A? receptor agonist GS-9667 had no significant effect on gene expression of both SREBP-(1c) and FAS in livers of Sprague Dawley rats. Taken together, our data suggest that the expression of adenosine A? receptor is too low to play a major role in the regulation of lipogenic gene expression in hepatocytes.     

Ferulic acid improves lipid and glucose homeostasis in high‐fat diet‐induced obese mice

Ferulic acid (FA) is a plant phenolic acid that has several pharmacological effects including antihyperglycaemic activity. Thus, the objective of this study is to investigate the effect of FA on glucose and lipid metabolism in high‐fat diet (HFD)‐induced obese mice. Institute for Cancer Research (ICR) mice were fed a HFD (45 kcal% fat) for 16 weeks. At the ninth week of induction, the obese mice were orally administered with daily FA doses of 25 and 50 mg/kg for the next eight weeks. The results show that FA significantly reduced the elevated blood glucose and serum leptin levels, lowered the insulin resistance, and increased the serum adiponectin level. Moreover, serum lipid level, and liver cholesterol and triglyceride accumulations were also reduced. The histological examination showed clear evidence of a decrease in the lipid droplets in liver tissues and smaller size of fat cells in the adipose tissue in the obese mice treated with FA. Interestingly, FA reduced the expression of hepatic lipogenic genes such as sterol regulatory element‐binding protein 1c (SREBP1c), fatty acid synthase (FAS), and acetyl‐CoA carboxylase (ACC). It could also up‐regulate hepatic carnitine palmitoyltransferase 1a (CPT1a) gene and peroxisome proliferator‐activated receptor alpha (PPARα) proteins. The FA treatment was also found to suppress the protein expressions of hepatic gluconeogenic enzymes, phosphoenolpyruvate carboxylase (PEPCK) and glucose‐6‐phosphatase (G6Pase). In conclusion, the findings of this study demonstrate that FA improves the glucose and lipid homeostasis in HFD‐induced obese mice probably via modulating the expression of lipogenic and gluconeogenic genes in liver tissues.     

Endoplasmic reticulum stress is involved in hepatic SREBP-1c activation and lipid accumulation in fructose-fed mice

A link between fructose drinking and nonalcoholic fatty liver disease (NAFLD) has been demonstrated in human and rodent animals. The aim of the present study was to investigate whether endoplasmic reticulum (ER) stress is mediated in the development of fructose-induced NAFLD. Female CD-1 mice were fed with 30% fructose solution for eight weeks. Hepatic lipid accumulation was assessed. Hepatic nuclear sterol regulatory element-binding protein (SREBP)-1c was measured. Results showed that hepatic SREBP-1c was activated in mice fed with fructose solution. Fatty acid synthase (fas) and acetyl-CoA carboxylase (acc), two target genes of SREBP-1c, were up-regulated. Fructose-evoked hepatic SREBP-1c activation seemed to be associated with insulin-induced gene (Insig)-1 depletion. An ER stress and unfolded protein response (UPR), as determined by an increased glucose-regulated protein (GRP78) expression and an increased eIF2α and PERK phosphorylation, were observed in liver of mice fed with fructose solution. Phenylbutyric acid (PBA), an ER chemical chaperone, not only significantly attenuated ER stress, but also alleviated fructose-induced hepatic Insig-1 depletion. PBA inhibited fructose-evoked hepatic SREBP-1c activation and the expression of SREBP-1c target genes, and protected against hepatic lipid accumulation. In conclusion, ER stress contributes, at least in part, to hepatic SREBP-1c activation and lipid accumulation in fructose-evoked NAFLD.     

普罗布考干预大鼠非酒精性脂肪肝形成的作用及机制研究

目的：探究普罗布考对大鼠非酒精性脂肪肝形成作用的干预情况及干预机制。方法选取30只SD大鼠,将其随机分为空白组、高脂组及研究组,每组10只。给予相应喂养方法,通过高脂饮食诱发实验大鼠出现NAFLD,建立模型,喂养18周后,处死全部大鼠,并进行血脂及肝功能相关指数,即TC、TG、AST、ALT及HDL与LDL水平,计算肝脏指数同时检测其肝脏组织FXR、SHP及SREBP-1c mRNA表达情况。结果3组大鼠肝脏病变程度均以高脂组最高,空白组最低,研究组脂肪性病变、炎性程度及纤维化病变评分分别为（2?．97±0．18）分、（1．29±0．27）分及（0．05±0．02）分,均位于其他2组评分之间。高脂组与研究组TC、ALT、AST及LDL与空白组比较均明显升高,且高脂组升高程度更为明显（ P ＜0．05）,空白组FXR、SHP及SREBP-1c的mRNA水平分别为（0．92±0．42）β-actin、（1．01±0．60）β-actin、（0．68±0．27）β-actin,各检测项目均显著高于高脂组（ P ＜0．05）,研究组FXR、SHP的mRNA表达水平位于其他2组之间,分别为（0．28±0．13）β-actin及（0．42±0．23）β-actin,差异有统计学意义（ P ＜0．05）,而SREBP-1c的mRNA表达水平为（0．68±0．22）β-actin,与空白组基本相同（ P ＞0．05）。结论普罗布考对由高脂饮食导致的大鼠NAFLD症状具有一定的预防作用,可明显减轻由该因素导致的大鼠肝脏出现脂肪性样变情况,其预防机制为该药物提高了大鼠机体的抗氧化能力,从而降低了组织出现氧化应激而导致的损伤。     

二氢杨梅素经激活SIRT1-AMPK通路抑制高脂饮食诱导的肥胖小鼠肝脏脂质沉积

目的探究二氢杨梅素(dihydromyricetin,DHM)对高脂饮食诱导的肥胖小鼠肝脏脂质蓄积的作用及其机制。方法C57BL/6J小鼠60只,随机分为6组(n=10):①ND组:正常饲料;②ND+L-DHM组:正常饲料+低剂量DHM(125 mg·kg^-1·d^-1);③ND+H-DHM组:正常饲料+高剂量DHM(250 mg·kg^-1·d^-1);④HFD组:高脂饲料;⑤HFD+L-DHM组:高脂饲料+低剂量DHM;⑥HFD+H-DHM组:高脂饲料+高剂量DHM。记录小鼠体重;16周后,测空腹血脂;计算体脂重量;肝脏HE和油红O染色;荧光定量PCR和Western blot检测肝脏SIRT1、AMPK、ACC、FAS、SREBP-1和PPARα、CPT1的表达。结果与ND组相比,HFD组小鼠体重、体脂、血清TG、TC、HDL水平明显增加;肝脏内脂肪蓄积增加,肝脏SREBP-1c、FAS、ACC1表达增加,而PPARα、CPT1、SIRT1和AMPK表达下降。经DHM处理后,HFD小鼠上述指标发生逆转;但ND小鼠上述指标无明显改变。结论DHM可能通过激活SIRT1-AMPK通路抑制脂质合成,促进脂质分解,改善高脂饮食诱导的肥胖小鼠肝脏脂质沉积。     

蚯蚓冻干粉对高血脂症小鼠载脂蛋白AI和载脂蛋白B基因表达的影响

目的研究蚯蚓冻干粉(earthworm lyophilized powder,ELP)的降血脂作用是否与调节载脂蛋白AI(apolipoproteinAI,ApoAI)和载脂蛋白B(apolipoprotein B,ApoB)基因表达有关。方法健康昆明种小鼠60只,随机分为5组,基础饲料组(normal diet control group,NCG)、高脂饲料组(high fatdiet control group,HCG)、高脂饲料+高剂量ELP组(high-dose gavage group,HDG)、高脂饲料+中剂量ELP组(middle-dose gavage group,MDG)、高脂饲料+低剂量ELP组(low-dose gavage group,LDG)。ELP干预10周后,测定各组小鼠血脂水平,RT-PCR测定各组小鼠肝脏ApoAI、ApoB mRNA表达量。结果 ELP明显降低高血脂小鼠血浆TG(totalcholesterol)、TG(triglycerol)和LDL-C(low-density lipoprotein-cholesterol)水平,同时升高HDL-C(high-density lipoprotein-cholesterol)水平。HDG组和MDG组小鼠ApoAI mRNA表达量明显上升,ApoB mRNA表达量明显降低。结论 ELP具有明显的降血脂作用,其降血脂作用可能与其调节载脂蛋白基因表达有关。     

蛇床子素通过激活过氧化物酶体增殖物激活受体α调节肝细胞内脂肪酸代谢

目的探讨蛇床子素是否通过激活过氧化物酶体增殖物激活受体(PPAR)α调节肝细胞内的脂肪酸代谢。方法 大鼠肝细胞在用蛇床子素12.5～100μmol.L-1作用24 h后,用比色法测定细胞内甘油三酯(TG)和游离脂肪酸(FFA)含量,用逆转录聚合酶链反应法测定PPARαmRNA表达的变化。PPARα抑制剂MK886 1μmo.lL-1预处理肝细胞2 h后,观察蛇床子素100μmo.lL-1作用24 h后对细胞内TG和FFA含量以及PPARα调控的靶基因包括固醇调节元件结合蛋白(SREBP)-1/2、脂肪酸合酶(FAS)、二脂酰甘油酰基转移酶(DGAT)、肉碱软脂酰转移酶(CPT)-1a、脂肪酸转运蛋白(FATP)4和肝脂肪酸结合蛋白(L-FABP)mRNA表达的影响。结果 蛇床子素12.5～100μmol.L-1可明显降低肝细胞内TG和FFA的含量(P<0.01),同时也能明显增加肝细胞内PPARαmRNA的表达(P<0.01)。在用PPARα抑制剂MK886预处理后,蛇床子素降低肝细胞内TG和FFA的作用则明显被减弱(P<0.01),同时抑制SREBP-1/2,FAS和DGAT mRNA表达的作用明显减弱或完全消失(P<0.01),增加CPT-1a,FATP4和L-FABPmRNA表达的作用也明显减弱或完全消失(P<0.01)。结论 蛇床子素通过激活肝细胞中PPARα后可降低细胞中的TG和FFA含量,其机制与激活PPARα后随后抑制SREBP-1/2,FAS和DGAT的基因表达以及增加CPT-1a,FATP4和L-FABP的基因表达有关。