胰岛素、胰高血糖素对体外培养犊牛肝细胞脂合成作用的影响

为确定胰岛素(insulin,INS)和胰高血糖素(glucagon,GLN)对奶牛肝细胞脂合成作用的影响,本试验体外培养犊牛原代肝细胞,分别用不同浓度的INS和GLN处理肝细胞:对照组(0nmol/L)、浓度梯度组(1,10,100,1 000nmol/L)。培养1h后分别用免疫印迹(Western blot,WB)方法、荧光定量PCR(qRT-PCR)方法以及细胞免疫荧光(immunofluorescence,IF)方法检测INS和GLN处理体外培养肝细胞对关键转录因子固醇调节元件结合蛋白-1c(SREBP-1c)mRNA表达水平,SREBP-1c核质分布以及下游靶基因脂代谢关键酶乙酰辅酶A羧化酶(ACC)和脂肪酸合成酶(FAS)mRNA表达水平的影响。结果显示:INS处理使SREBP-1c的表达水平和转录活性显著升高,入核量显著增加,其下游的脂合成关键酶ACC和FAS的基因表达水平也显著升高。而与之相反,GLN处理使SREBP-1c的表达水平和转录活性显著降低,入核量显著减少,其下游的脂合成关键酶ACC和FAS的基因表达水平也显著降低。以上结果说明,INS可通过增强SREBP-1c的活性从而促进肝细胞脂合成,增加肝脂沉积;而GLN则通过抑制SREBP-1c的活性从而降低肝细胞脂合成。     

催乳素调控肝脏细胞脂代谢的信号机制

催乳素(prolactin,PRL)是启动和维持泌乳所必须的激素,在泌乳期间能够优先将机体营养物质和能量流向乳腺,用于乳脂和乳蛋白的合成。本试验采用体外分离培养奶牛肝脏细胞,分别添加PRL和磷脂酰肌醇3-激酶(phosphoinositide 3-kinase,PI3K)抑制剂LY294002、PRL和酪氨酸蛋白激酶2(janus kinase 2,JAK2)抑制剂AG490,通过甘油三脂(triglyceride,TG)测定试剂盒测定细胞内TG含量,以确定PRL的脂质合成通路,进而探讨其对脂合成相关基因的作用。结果显示,PRL通过PI3K-Akt信号通路促进奶牛肝脏细胞TG的合成,此时关键转录因子固醇调节元件结合蛋白-1c(SREBP-1c)的表达活性和转录活性及下游控制脂合成的脂肪酸合成酶(FAS)、乙酰辅酶A羧化酶1(ACC1)基因表达均显著升高。而与之相反,添加LY294002之后,SREBP-1c基因的表达活性和转录活性及下游基因FAS、ACC1的表达则显著降低。结果表明,PRL通过PI3K-Akt通路调节SREBP-1c、FAS和ACC1的表达来调控肝脏细胞的TG合成。     

苜蓿源miR168b通过靶向肉碱棕榈酰转移酶1A对奶牛乳腺上皮细胞增殖、凋亡和脂滴积累的调控研究北大核心CSCD

本试验旨在探究苜蓿源miRNAs(mtr-miRNAs)对奶牛乳腺上皮细胞(BMECs)增殖和凋亡的影响。试验首先通过CCK8、5-乙炔基-2′脱氧尿嘧啶核苷(EdU)、流式细胞术、基因和蛋白定量等方法检测苜蓿源-miR168b(mtr-miR168b)对BMECs增殖、凋亡和周期的影响。然后,敲低mtr-miR168b靶基因肉碱棕榈酰转移酶1A(CPT1A)表达后,检测了BMECs的活力和凋亡。通过诱导转染后细胞,用氟硼二吡咯(Bodipy)染色和油红O染色检测mtr-miR168b和CPT1A基因干扰对BMECs脂滴合成的影响。结果表明:1)mtr-miR168b高表达极显著降低了BMECs活力(P<0.01)。2)mtr-miR168b高表达极显著抑制了BMECs增殖(P<0.01),延长了细胞G1~S期进程,极显著促进了细胞凋亡(P<0.01)。3)mtr-miR168b在BMECs中高表达极显著抑制了细胞增殖基因周期蛋白依赖性激酶4(CDK4)、增殖细胞核抗原(PCNA)、细胞周期蛋白D1(Cyclin D1)和细胞周期蛋白D2(Cyclin D2)的基因的表达水平(P<0.01),极显著增加了凋亡标志基因Bcl2关联X蛋白(BAX)基因的表达水平(P<0.01),极显著抑制了PCNA蛋白表达水平(P<0.01),极显著增加了BAX蛋白表达水平(P<0.01),并且mtr-miR168b显著抑制了蛋白激酶B(AKT)和哺乳动物雷帕霉素靶蛋白(mTOR)基因的表达水平(P<0.05)。4)mtr-miR168b高表达抑制了BMECs中脂滴的积累。5)干扰mtr-miR168b的靶基因CPT1A,对BMECs脂滴积累也有抑制作用。综上所述,mtr-miR168b可通过抑制BMECs增殖,促进细胞凋亡,并通过靶向CPT1A基因抑制BMECs中脂滴的生成。试验结果可为mtr-miRNAs调控牛奶乳脂合成提供分子层面的技术支撑。     

饥饿诱发成脂分化C2C12细胞中脂滴形态重塑

试验旨在探究短期饥饿处理对成脂分化C2C12细胞中脂滴生长发育的影响,为阐释及利用补偿生长机制奠定基础。通过胰岛素等激素混合物诱导C2C12细胞成脂分化,将成脂分化12 d的C2C12细胞分为两组：对照组（Control）,高糖培养24 h;饥饿处理组（FAST）,无血清低糖培养24 h。通过BODIPY染色和甘油三酯测定观察脂滴形态变化,并使用Western blotting方法测定脂滴表面结构蛋白perilipin1-5表达量的变化。结果显示,C2C12细胞成脂诱导12 d,可以使细胞达到较好的充脂状态。通过无血清低糖饥饿处理后,成脂分化C2C12细胞中甘油三酯含量极显著下降（P<0.01）;脂滴平均尺寸极显著减小（P<0.01）,脂滴平均数量极显著增多（P<0.01）;脂滴表面结构蛋白出现变化,perilipin2、perilipin5表达极显著上调（P<0.01）、perilipin3表达显著上调（P<0.05）。综上,无血清低糖处理可以诱发脂滴形态重塑,改变脂滴表面结构蛋白的表达。     

银杏叶提取物对高脂饮食诱导肥胖犬脂肪沉积及脂质代谢的影响

文章旨在研究银杏叶提取物对高脂饮食诱导肥胖犬脂肪沉积及脂质代谢的影响，试验选取雄性成年泰迪型贵宾犬30只，等分成5组，分别为对照组（CD）、高脂饲粮组（HFD）、低剂量银杏叶提取物组（LGL）、中剂量银杏叶提取物组（MGL）和高剂量银杏叶提取物组（HGL）。CD组饲喂普通饲粮，HFD组饲喂高脂饲料，各银杏叶提取物饮食组分别饲喂含1%、3%和5%银杏叶提取物的高脂饲料，试验为期8周。结果显示，与HFD组相比，MGL组和HGL组体重和体脂率显著降低（P＜0.05）|MGL组和HGL组血清TG、LDL-C含量降低，HDL-C升高（P＜0.05）|MGL组和HGL组脂肪细胞面积变小（P＜0.05）|MGL组和HGL组AMPK α1的mRNA表达量上调，SREBP-1、FAS及PPARγ的mRNA表达量下调|LGL组CTP-1蛋白表达量升高，FAS蛋白表达量降低，MGL组和HGL组AMPK α1及CPT-1蛋白表达量升高，ACC1、SREBP-1、FAS及PPARγ蛋白表达量降低。综上所述，银杏叶提取物具有促进肥胖犬脂质代谢，抑制脂肪沉积作用。 [关键词]银杏叶提取物|高脂饮食|肥胖犬|脂肪沉积|脂质代谢     

大鼠脂肪细胞分化过程中脂代谢相关基因转录表达时序的研究

对大鼠附睾和肾周脂肪组织分离的前体脂肪细胞原代培养，采用RT—PCR法分析脂代谢重要酶和转录因子基因在不同分化阶段转录表达的时序变化。结果显示，在前体脂肪细胞阶段，固醇调控元件结合蛋白（SREBP）-1c、碳水化合物反应元件结合蛋白（ChREBP）以及脂肪酸合成酶（FAS）、乙酰辅酶A羧化酶α（ACC1）、硬酯酰辅酶A去饱和酶（SCD）和激素敏感脂酶（HSL）基因均不转录表达；HSL mRNA在分化初期表达，中期表达水平最高，分化末期降低；SCD mRNA在分化中期表达，末期表达水平显著提高；分化初期FAS mRNA水平明显高于中期和末期；ACC1 mRNA仅在末期表达；分化初期SREBP-1c mRNA水平较高，中期和末期显著下降；ChREBP mRNA表达水平在分化末期稍高于中期，但差异不显著。表明，SREBP-1c mRNA的表达与脂肪细胞早期分化调控有关，分化成熟脂肪细胞的ChREBP mRNA表达可能与生脂基因的转录激活有关。     

ADCY2基因表达对延边黄牛脂肪前体细胞成脂分化的影响

本试验旨在研究环腺苷酸（3',5'-cyclic adenosine monophosphote,cAMP）环化酶合成酶2（adenylyl cyclase 2,ADCY2）基因对延边黄牛脂肪前体细胞成脂分化的影响。选取3日龄的延边黄牛腹股沟皮下脂肪组织进行脂肪前体细胞的分离、培养和诱导分化;设计ADCY2基因的干扰片段（siADCY2-1、2、3）,构建pEX4过表达载体;分别收集正常诱导（对照组）、干扰和过表达0、5和10 d的脂肪细胞。用实时荧光定量PCR检测过氧化物酶体增殖激活物受体（PPARγ）、CCAAT/增强子结合蛋白（C/EBPα）和ADCY2在细胞分化过程中mRNA的转录水平,并用Western blotting法检测其蛋白的表达;用油红O染色检测脂滴含量的变化;用甘油三酯试剂盒检测甘油三酯含量。试验结果表明,在成脂分化过程中,与未分化相比,ADCY2基因在分化的第5和10天表达量均极显著上升（P<0.01）,而分化第10天与第5天相比水平极显著下降（P<0.01）;siADCY2-1干扰效率最高,过表达ADCY2基因使其mRNA水平升高;与对照组相比,过表达组细胞内ADCY2基因mRNA水平提高了约4 000 000倍,脂肪细胞内脂滴含量和甘油三酯的含量极显著提高（P<0.01）,成脂关键基因C/EBPα和PPARγ表达极显著上调（P<0.01）,而RNA干扰组细胞内ADCY2基因mRNA水平极显著降低（P<0.01）,脂肪细胞内脂滴含量和甘油三酯的含量极显著下降,成脂关键基因C/EBPα和PPARγ表达极显著下调（P<0.01）。因此,ADCY2基因过表达能显著增加成熟脂肪细胞的脂滴含量及甘油三酯含量,促进成脂关键基因C/EBPα和PPARγ的表达,说明ADCY2基因对脂肪细胞分化具有正向调控作用。     

黄羽肉鸡日粮中添加胆汁酸盐对肠道黏膜转运蛋白及消化酶的影响

试验旨在研究日粮中添加不同水平的胆汁酸盐对黄羽肉鸡雏鸡肠道黏膜转运蛋白(SREBF1、FATP4)及消化酶(FAS、ACC)基因表达的影响。将420只雏鸡分为7组,试验1组为阴性对照组饲喂基础日粮,试验2组为阳性对照组,在基础日粮上添加0.02%泰乐菌素代替麸皮,试验3组、试验4组、试验5组、试验6组、试验7组分别用0.015%、0.025%、0.035%、0.045%、0.055%的胆汁酸盐代替麸皮。雏鸡饲养28 d,在28日龄时采集十二指肠、空肠、回肠和肝脏,通过实时荧光定量PCR技术对各组织相应目的基因进行表达量测定。结果显示:黄羽肉鸡不同组织SREBF1、FATP4、FAS、ACC mRNA的相对表达量均存在极显著差异(P<0.01);不同胆汁酸盐添加水平黄羽肉鸡肠道SREBF1、FATP4、FAS、ACC mRNA相对表达量存在极显著差异(P<0.01)。由此可见,黄羽肉鸡肠道营养转运蛋白SREBF1、FATP4及消化酶FAS、ACC基因表达具有肠段及胆汁酸盐添加水平的差异性。日粮添加0.055%胆汁酸盐,对于肠道整体营养转运蛋白及消化酶的基因表达影响最佳。     

雌激素调控奶牛乳腺上皮细胞凋亡及生长周期作用机制的研究

试验旨在研究雌激素对奶牛乳腺上皮细胞（BMECs）凋亡及生长周期的影响。通过添加MAPK/ERK信号通路阻断剂探索雌激素调控BMECs凋亡及生长周期具体的作用机制,采用流式细胞仪检测细胞凋亡及周期的变化情况,实时荧光定量PCR检测Bcl-2、Caspase3及CyclinD1基因mRNA的表达丰度。结果显示,对照组BMECs凋亡率极显著低于BMECs+PD98059、BMECs+E₂+PD98059组（P<0.01）,Bcl-2 mRNA表达丰度极显著高于BMECs+PD98059组（P<0.01）,Caspase3 mRNA表达丰度显著低于BMECs+PD98059组（P<0.05）;对照组细胞比例在G1期显著高于BMECs+E₂组（P<0.05）,极显著低于BMECs+E₂+PD98059组（P<0.01）,S期细胞比例极显著高于BMECs+PD98059、BMECs+E₂+PD98059组（P<0.01）,G2期细胞比例极显著低于BMECs+PD98059、BMECs+E₂+PD98059组（P<0.01）;对照组CyclinD1 mRNA的表达丰度极显著高于BMECs+PD98059组（P<0.01）;BMECs+E₂+PD98059组的Bcl-2 mRNA的表达量极显著高于BMECs+PD98059组（P<0.01）,Caspase3 mRNA的表达量显著低于BMECs+PD98059组（P<0.05）。结果表明,MAPK/ERK信号通路参与BMECs的增殖及细胞生长周期调节的过程,且雌激素可通过MAPK/ERK信号通路抑制BMECs的凋亡,MAPK/ERK信号通路可能参与由雌激素调控的细胞生长周期的进程。     

刺葡萄汁对大鼠血脂代谢影响的研究

通过研究刺葡萄汁对动物血脂代谢的影响,探讨其调节血脂代谢的可能机制。选取6周龄大鼠60只,随机分为6组:空白对照组(基础饲料+生理盐水)、模型对照组(高脂饲料+生理盐水)、阳性药物组(高脂饲料+血脂康胶囊)、刺葡萄汁处理组(高脂饲料+低、中、高剂量刺葡萄汁)。每组10个重复,采用脂代谢紊乱法,试验干预6周。采用全自动血液生化分析仪检测并分析大鼠体质量、血脂指标、血清内谷丙转氨酶(ALT)和谷草转氨酶(AST)的活力,肝脏组织内抗氧化指标超氧化物歧化酶(SOD)、谷胱甘肽过氧化酶(GSH-PX)和丙二醛(MDA)及血脂代谢相关基因的相对表达量。结果表明:刺葡萄汁能显著抑制大鼠体质量的增长;所有剂量刺葡萄汁能极显著(P<0.01)降低甘油三酯(TG)和低密度脂蛋白胆固醇(LDL-C)含量,中剂量刺葡萄汁显著(P<0.05)降低总胆固醇(TC),极显著(P<0.01)升高高密度脂蛋白胆固醇(HDL-C)水平;所有剂量刺葡萄汁能极显著(P<0.01)升高大鼠肝脏内GSH-PX、SOD的活性,低中剂量极显著(P<0.01)降低肝脏MDA的含量;刺葡萄汁各剂量处理均能上调LCAT、MCD、CPT-1基因的表达,下调ACAT1、DGAT2、UCP2、SREBP-1和FAS基因的表达,低剂量、中剂量刺葡萄汁处理组与模型组相比均达到了显著(P<0.05)或极显著(P<0. 01)水平,高剂量刺葡萄汁处理在DGAT2、CPT-1和SREBP-1基因表达上与模型组相比无显著性差异。因而,低、中剂量的刺葡萄汁具有一定的调节血脂功能。     

Effect of Fatty Acid Binding Protein 5 on Milk Fat Synthesis of Bovine Mammary Epithelial Cells

The fatty acid binding protein 5 (FABP5) is an intracellular lipid carrier. The TG GPO-POD assay kit and BODIPY staining methods were used to detect lipid secretion and triglyceride content,and the effect of FABP5 on SREBP-1c expression were detected by Real-time PCR and Western blotting methods. The results showed that high purity bovine mammary epithelial cells (BMECs) were successfully isolated and purified,and the eukaryotic expression vector pGCMV-IRES-EGFP-FABP5 was constructed in this experiment. Compared with the blank control group and empty vector group,the lipid secretion and triglyceride content, and the expression of SREBP-1c and FAS,ACC were extremely significantly increased when the FABP5 was overexpressed (P<0.01). FABP5 siRNA1 was selected as the optimal interference fragment, and when FABP5 was inhibited,the lipid secretion and triglyceride content,the expression of SREBP-1c,FAS and ACC were extremely significantly decreased (P<0.01).The results indicated that FABP5 could promote the synthesis of milk fat in BMEC by up-regulating the expression of SREBP-1c.     

Effect of maternal rearing on lipid metabolism-related gene expression in offspring broilers during embryonic development

1. The aim of this study was to investigate the effect of maternal rearing on lipid metabolism and lipid metabolism-related gene expression in offspring broilers during embryonic development. 2. One hundred laying Sanhuang breeders were divided into two groups, and either floor-reared or cage-reared on the same diet. Liver and serum samples were extracted on days 14 and 19 of embryonic development and at hatching. The lipid metabolism related gene expressions of acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), malic enzyme (ME), apolipoprotein B100(apoB100), sterol regulating element binding protein (SREBP-1c), carnitine palmitoyltransferase (CPT-1) and peroxisome proliferators-activated receptor (PPARα) genes were determined using real time RT-PCR. 3. The results showed that embryonic weight, liver weight, serum and hepatic total cholesterol (TC) concentration and serum triglyceride (TG) content were not significantly different between the cage-reared group and the floor-reared group during embryonic development. However, embryonic weight, liver weight, serum and hepatic TC concentration and serum TG content in the cage-reared group were significantly higher than in the floor-reared group at hatching. 4. Hepatic ACC, FAS, SREBP-1c, ME and apoB genes expression were not significantly different between the cage-reared and the floor-reared groups during E9 and E14 development. Hepatic ME gene expression in the cage-reared group was higher than in the floor-reared group during E19 development. However, hepatic FAS, SREBP-1c, CPT-1 and PPARα gene expressions in the cage-reared group was higher than in the floor-reared group. 5. A change in the maternal regime could regulate lipid metabolism in offspring broilers during embryonic development, and especially at hatching.     

纳米氧化锌对育肥牛生产性能、血清指标和背最长肌肌内脂肪沉积相关基因表达的影响

本试验旨在研究纳米氧化锌对育肥牛生产性能、血清指标及背最长肌肌内脂肪(IMF)沉积相关酶活性和基因表达的影响。选用16头西杂阉公牛(西门塔尔牛×本地黄牛),随机分2组,每组8个重复,每个重复1头牛。对照组饲喂基础饲粮(不添加锌),纳米氧化锌组在基础饲粮的基础上添加80 mg/kg锌(纳米氧化锌形式)。试验期为60 d。结果表明：1)与对照组相比,添加纳米氧化锌显著提高了育肥牛的平均日增重(P<0.05),显著降低了料重比(P<0.05)。2)与对照组相比,添加纳米氧化锌极显著提高了血清游离脂肪酸、甘油三酯、总胆固醇、高密度脂蛋白、低密度脂蛋白、葡萄糖和胰岛样生长因子-Ⅰ含量(P<0.01),显著提高了胰岛素含量(P<0.05),极显著降低了葡萄糖/胰岛素比值(P<0.01)。3)与对照组相比,添加纳米氧化锌显著提高了背最长肌IMF含量和乙酰辅酶A羧化酶(ACC)活性(P<0.05),极显著降低了激素敏感脂肪酶(HSL)活性(P<0.01),显著降低肉碱转移酶-1(CPT-1)和脂蛋白脂肪酶(LPL)活性(P<0.05)。4)与对照组相比,...     

日粮蛋白质水平对乌金猪肝脏组织脂类代谢相关基因表达的影响

为探讨日粮蛋白质水平对乌金猪肝脏组织脂类代谢相关基因表达的影响,试验选取体重约15 kg的乌金猪54头,随机分为3组,每组18头,为低、中和高蛋白质组,其在15～30、30～60及60～100 kg生长阶段的蛋白质水平分别为14%、12%、10%,16%、14%、12%和18%、16%、14%。猪在体重为30、60和100 kg时屠宰,取其肝脏组织,Real-time PCR定量检测脂类代谢相关基因的表达水平。结果显示,在30、60和100 kg时,乌金猪肝脏组织中ACC、FAS、SREBP-1C基因的表达水平均随着蛋白质水平的升高而降低;CPT-Ⅰ和PPARα基因的表达水平则随着蛋白质水平的升高而升高。由此表明,日粮高蛋白质水平显著降低肝脏脂肪酸合成代谢基因(ACC、FAS和SREBP-1C)的表达(P<0.05),提高脂肪酸分解代谢基因(CPT-Ⅰ和PPARα)的表达水平(P<0.05);脂肪酸合成减少,且被氧化的量增加,两者共同作用导致用于合成甘油三酯(TG)的脂肪酸含量降低,从而减少了从肝脏组织被运输到各个组织的TG含量,使机体沉积TG的能力降低。     

丁酸钠通过AMPK通路调控LPS造成牛乳腺上皮细胞脂代谢紊乱的作用机制

通过向脂多糖（LPS）诱导牛乳腺上皮细胞系（MAC-T）脂代谢紊乱模型中添加不同浓度（2、8、16 μmol·L^-1）的丁酸钠,探讨其对细胞脂代谢的调控机理及炎症损伤的修复作用。分别用1 000 ng·mL^-1 LPS刺激MAC-T细胞9 h后,检测细胞脂滴面积及三酰甘油（TG）含量;用不同浓度的丁酸钠刺激MAC-T细胞12 h后,流式细胞术检测细胞凋亡率;试验共分为5组：对照组、LPS处理组、2 μmol·L^-1丁酸钠+LPS处理组、8 μmol·L^-1丁酸钠+LPS处理组和16 μmol·L^-1丁酸钠+LPS处理组,分别对细胞TG含量、AMPK信号通路蛋白、脂代谢关键基因以及相关炎症因子进行检测。结果显示：LPS会造成MAC-T细胞总脂滴面积显著下降（P<0.05）,TG含量极显著下降（P<0.01）;不同浓度的丁酸钠对MAC-T细胞凋亡率没有影响;与对照组相比,LPS处理组TG含量极显著下降（P<0.01）、P-AMPK表达水平显著上升（P<0.05）、脂合成代谢相关基因ACC、SCD-1以及FAS mRNA表达水平均显著（P<0.05）或极显著（P<0.01）下降、脂分解代谢相关基因CPT-1、CPT-2以及ACO mRNA表达水平均显著上升（P<0.05）、炎症因子TNF-α和IL-6含量显著上升（P<0.05）;与LPS处理组相比,（2、8、16 μmol·L^-1）丁酸钠+LPS处理组TG含量有一定程度上升,P-AMPK表达水平下降,脂合成代谢相关基因表达水平上升,脂分解代谢相关基因表达水平有一定程度下降,炎症因子TNF-α和IL-6含量下降。本研究表明丁酸钠会通过AMPK通路激活脂合成代谢,调控TG的合成,并且对MAC-T细胞的炎症损伤具有一定的缓解作用。     

Lipogenic gene expression in abdominal adipose and liver tissues of diet-induced overweight cats

The effect of overweight status on the expression of SREBP-1c and downstream lipogenic genes, such as ATP citrate lyase (ACL) and fatty acid synthase (FAS), in abdominal adipose and liver tissues was determined in cats using a diet-induced weight gain model. ACL and SREBP-1c mRNA expression was significantly reduced (～65% and 20%, respectively) in liver tissue, whereas FAS and SREBP-1c expression was significantly increased (～80% and 45%, respectively) in abdominal omental adipose tissue of overweight animals as compared to healthy animals. Additionally, ACL, FAS, and SREBP-1c expression was significantly reduced by ～50%, 75%, and 70%, respectively, in abdominal subcutaneous adipose tissue of overweight animals. Omental adipose tissue appeared to foster, whereas subcutaneous adipose and liver tissues appeared to defer lipid storage based on differences in SREBP-1c mRNA expression. Overall, reduced lipogenic gene mRNA expression patterns support the hypothesis that SREBP-1c expression is reduced in overweight and possibly obese cats, reflecting down-regulation of the lipogenic pathway to prevent further fat accumulation and weight gain.     

Effects of different levels of protein supplementary diet on gene expressions related to intramuscular deposition in early‐weaned yaks

This study was conducted to estimate different levels of protein supplementary diet on gene expressions related to intramuscular deposition in early‐weaned yaks. Results showed that supplementary dietary protein significantly increased final weight, average daily gain (ADG), intramuscular fat (IMF), serum free fatty acid (FFA), total triglycerides, total cholesterol (Ch), low‐density lipoprotein cholesterol (LDL) and high‐density lipoprotein cholesterol (HDL) content. There was a quadratic response of ADG, IMF, FFA, Ch, HDL and LDL to dietary crude protein (CP) level. Lipoprotein lipase (LPL), fatty acid synthase (FAS) and acetyl‐CoA carboxylase (ACC) enzyme activities were significantly increased by supplementary dietary CP, while hormone‐sensitive lipase (HSL) and carnitine palmitoyltransferase‐1 (CPT‐1) activities were significantly decreased. LPL, ACC and FAS enzyme activities showed quadratic increase as dietary CP increased. Peroxisome proliferator‐activated receptor γ (PPARγ), LPL, FAS, sterol regulatory element binding protein 1 (SREBP‐1), ACC, stearoyl‐CoA desaturase (SCD) and heart fatty‐acid binding protein (H‐FABP) gene expression were significantly increased by supplementary dietary CP, while HSL and CPT‐1 gene expression were significantly decreased. PPARγ, LPL, SREBP‐1, ACC and H‐FABP gene expression showed quadratic increase as dietary CP increased. These results indicated that supplementary dietary protein increased IMF accumulation mainly to increased intramuscular lipogenic gene expression and decreased lipolytic gene expression.     

Potential predictive biomarkers of obesity in Burmese cats

Australian Burmese cats are predisposed to diabetes mellitus and, compared to other breeds, have delayed triglyceride clearance that may result in subtle changes within cells and tissues that trigger specific alterations in gene expression within peripheral blood leucocytes (PBLs). Expression of genes involved in energy metabolism (glucose-6-phosphate dehydrogenase and malate dehydrogenase), lipogenesis (ATP citrate lyase [ACL], fatty acid synthase [FAS] and sterol regulatory binding protein-1c [SREBP-1c]), and insulin signalling (insulin receptor substrates 1 and 2, and phosphatidylinositol-3 kinase), as well as cholesterol lipoprotein subfraction profiling were carried out on PBLs from lean Burmese cats and compared with similar profiles of age and gender matched lean and obese Australian domestic shorthaired cats (DSHs) in an attempt to identify possible biomarkers for assessing obesity.For the majority of the genes examined, the lean Burmese cats demonstrated similar PBL gene expression patterns as age and gender matched obese Australian DSH cats. Lean Burmese had increased expression of ACL and FAS, but not SREBP-1c, a main upstream regulator of lipid synthesis, suggesting possible aberrations in lipogenesis. Moreover, lean Burmese displayed a 3- to 4-fold increase in the very low density cholesterol fraction percentage, which was double that for obese DSH cats, indicating an increased degree of lipid dysregulation especially in relation to triglycerides. The findings suggest that Burmese cats may have a particular propensity for dysregulation in lipid metabolism.     

2种日粮对不同生长阶段乌金猪脂肪组织脂类合成代谢相关基因表达的影响

为探讨不同日粮对乌金猪不同生长阶段脂类合成代谢相关基因表达的影响,试验选取体重约23 kg乌金猪36头,公、母各半,随机分为2个处理组,每个处理组3个重复,每个重复6头。处理1组饲喂乌金猪日粮,处理2组饲喂NRC日粮。分别于30、60和100 kg体重时屠宰,通过Real-time PCR比较研究3个脂肪合成代谢相关基因在脂肪组织中表达的差异。结果显示,体重30 kg时,处理1组脂肪酸合成酶(fatty acid synthase,FAS)的相对表达量显著低于处理2组(P<0.05),60和100 kg时,处理1组FAS基因的相对表达量高于处理2组,60 kg时达到显著水平(P<0.05);在各个体重时,处理1组固醇调节元件结合蛋白1c(sterol regulator element binding protein-1c,SREBP-1c)的相对表达量均高于处理2组,30和60 kg时达到显著水平(P<0.05);在各个体重时,处理1组二酰基甘油酰基转移酶1(diacylglycerol acyltransferase-1,DGAT-1)的相对表达量低于处理2组,100 kg时达到显著水平(P<0.05)。提示,不同日粮调控不同体重乌金猪脂类合成代谢相关基因表达存在着差异。