非酯化脂肪酸对原代犊牛肝细胞内质网应激信号通路的影响

通过体外添加一定浓度的非酯化脂肪酸(nonestesterifiedfatty acid,NEFAs)(1.8 mmol/L)处理犊牛原代肝细胞不同时间,运用Western blot和实时荧光定量PCR(qRT-PCR)方法,测定NEFAs对内质网应激(ER stress)标志分子IRE1α磷酸化水平和GRP78、CHOP、XBP-1的mRNA表达水平的影响。结果显示,随着NEFAs作用时间的增加,与0.5h组相比,IRE1α磷酸化水平逐渐升高,NEFAs处理小于5h时,IRE1α磷酸化水平呈时间依赖性增加。并在5h达到最高水平,极显著高于0.5h组(P0.01),此后,磷酸化水平降低。与0.5h组相比,GRP78、CHOP、XBP-1的mRNA的表达水平整体逐渐升高,NEFAs处理9h时极显著高于0.5h时组(P0.01)并达到最高水平。结果表明,一定浓度的NEFAs可诱导奶牛肝细胞发生内质网应激。     

非酯化脂肪酸对原代培养犊牛肝细胞胰岛素信号通路的影响

旨在探讨非酯化脂肪酸(nonestesterified fatty acids,NEFAs)对体外原代培养犊牛肝细胞胰岛素信号通路的影响及SIRT1在其中的调控作用。选择培养48h的原代犊牛肝细胞,添加不同浓度的NEFAs(0、0.6、1.2、1.8mmol/L),继续培养12h,胰岛素处理组在收样前用100nmol/L胰岛素处理30min,每个浓度3个重复。另外选取已培养48h的细胞,用SIRT1抑制剂Nicotinamide(10mmol/L)处理12h,胰岛素处理组在收样前用100 mmol/L胰岛素处理30min。运用免疫印迹Western blot方法,检测NEFAs和Nicotinamide对肝细胞胰岛素信号通路关键蛋白IR和Akt的磷酸化水平及SIRT1蛋白表达水平的影响。结果显示,与对照组相比,1.2、1.8 mmol/L NEFAs组胰岛素刺激的IR磷酸化水平显著降低(P0.01),而Akt的磷酸化程度在NEFAs浓度为0.6 mmol/L时即显著降低(P0.01),同时,SIRT1的蛋白表达水平在NEFAs为1.2、1.8mmol/L显著降低(P0.01);添加SIRT1抑制剂显著降低SIRT1的蛋白表达水平(P0.01),同时胰岛素刺激的Akt磷酸化水平也显著降低(P0.01)。结果表明,高浓度的NEFAs可以损伤体外原代培养肝细胞的胰岛素信号通路,SIRT1在NEFAs损伤的胰岛素信号通路中发挥重要作用。     

非酯化脂肪酸对体外培养犊牛原代肝细胞中炎性因子表达及其活性的影响

在建立犊牛原代肝细胞体外培养模型的基础上,通过培养液中添加不同浓度的非酯化脂肪酸(Nonesterified fatty acids,NEFAs),运用实时荧光定量PCR和ELISA方法,测定NEFAs对肝细胞中炎性因子TNFα、IL-6和IL-1β的mRNA表达及其活性的影响。结果显示,NEFAs作用肝细胞9h后,与对照组相比,高浓度NEFAs(1.8mmol/L)组肝细胞中TNFα、IL-1β的mRNA表达水平显著增加(P<0.05),IL-6的mRNA表达水平在2.4mmol/L时极显著增加(P<0.01),低浓度NEFAs(0.6、1.2mmol/L)组肝细胞中TNFα、IL-1β和IL-6的mRNA表达水平无显著差异(P>0.05);并且TNFα、IL-1β的活性在NEFAs浓度达到1.8、2.4mmol/L显著高于对照组(P<0.01),且呈剂量依赖性作用,IL-6的活性在在NEFAs浓度达到1.8mmol/L显著高于对照组(P<0.01),在2.4mmol/L也高于对照组,但差异不显著。结果表明,高浓度NEFAs在一定程度上能引起或加剧奶牛肝细胞炎性反应,可能是导致产后奶牛肝功能炎性损伤主要因素。     

NFκB-Orai1参与NEFA诱导的内质网应激

为探究NFκB-Orai1是否参与游离脂肪酸(NEFA)诱导的内质网应激,首先通过体外添加一定浓度的非酯化脂肪酸(nonestesterifiedfatty acid,NEFAs)(1.2 mmol/L)处理大鼠肝细胞不同时间,运用Western blot和实时荧光定量PCR(qRT-PCR)方法,测定NEFAs对内质网应激(ER stress)标志分子GRP78表达量以及钙通道相关蛋白Orai1表达水平的影响。结果显示NEFAs处理12 h时GRP78、Orai1表达量极显著高于对照组(P0.01),证明12 h NEFAs刺激诱导产生内质网应激效果最佳。而后又通过分别添加NFκB抑制剂wogonin与Orai1抑制剂2APB,结果显示抑制NFκB和Orai1后NEFAs刺激可明显降低GRP78、NFκB p65、Orai1的表达水平。结果表明NFκB-Orai1参与NEFA诱导的内质网应激。     

Orai1对NEFA诱导内质网应激引起犊牛肝细胞脂质沉积的影响

为探究Orai1是否参与非酯化脂肪酸(nonestesterifiedfatty acid,NEFAs)诱导内质网应激引起犊牛肝细胞脂质沉积,本试验首先通过体外添加高浓度NEFAs,运用Western blot和实时荧光定量PCR(qRT-PCR)方法,测定NEFAs对内质网应激标志分子GRP78表达量以及脂肪从头合成ACC1、FAS的表达水平的影响。而后又添加Orai1抑制剂2APB与RNA靶向沉默Orai1。结果显示,抑制或沉默Orai1后NEFAs刺激可明显降低GRP78、Orai1、ACC1、FAS的表达水平以及脂滴含量。结果表明,Orai1参与NEFA诱导的内质网应激引起犊牛肝细胞脂质沉积。     

非酯化脂肪酸对体外培养犊牛原代肝细胞中炎性因子表达及其活性的影响

在建立犊牛原代肝细胞体外培养模型的基础上，通过培养液中添加不同浓度的非酯化脂肪酸（Nonesterifiedfatty acids，NEFAs），运用实时荧光定量PCR和ELISA方法，测定NEFAs对肝细胞中炎性因子TNFα、IL-6和IL-1β的mRNA表达及其活性的影响。结果显示，NEFAs作用肝细胞9h后，与对照组相比，高浓度NEFAs（1．8mmol／L）组肝细胞中TNFα、IL-1β的mRNA表达水平显著增加（P〈0．05），IL-6的mRNA表达水平在2．4retool／L时极显著增加（P〈0．01），低浓度NEFAs（0．6、1．2mmol／L）组肝细胞中TNFα、IL-1β和IL-6的mRNA表达水平无显著差异（P〉0．05）；并且TNFα、IL-1G的活性在NEFAs浓度达到1．8、2．4mmol／L显著高于对照组（P〈0．01），且呈剂量依赖性作用，IL-6的活性在在NEFAs浓度达到1．8mmol／L显著高于对照组（P〈0．01），在2．4mmol／L也高于对照组，但差异不显著。结果表明，高浓度NEFAs在-定程度上能引起或加剧奶牛肝细胞炎性反应，可能是导致产后奶牛肝功能炎性损伤主要因素。     

NEFAs对BRL-3A氧化应激的作用

用非酯化脂肪酸(non-esterified fatty acids,NEFAs)刺激BRL-3A,添加钙释放激活的钙通道蛋白1(calcium release-activated calcium channel protein 1,CRAR,也叫Orai1)通路抑制剂2-氨基乙酯二苯基硼酸(2-APB),检测不同分组细胞内Orai1 mRNA表达量以及活性氧(ROS)、丙二醛(MDA)、还原型谷胱甘肽(GSH)水平的变化。结果显示,添加NEFAs的BRL-3A细胞中Orai1 mRNA表达量及ROS、MDA水平显著高于对照组,GSH水平显著低于对照组,经过2-APB预处理的NEFAs组细胞的Orai1 mRNA表达量和ROS、MDA水平显著低于NEFAs组,GSH水平显著高于NEFAs组。结果表明,NEFAs通过激活Orai1通路,使BRL-3A细胞的氧化应激水平显著上升,从而导致肝损伤,而抑制Orai1通路可下调NEFAs诱导的大鼠肝细胞氧化应激水平,进而保护肝脏。     

铁水平和孵育时间对原代培养肉鸡鸡胚肝细胞中铁含量及含铁酶活性、基因表达和蛋白表达的影响

本试验旨在研究铁水平和孵育时间对原代培养肉鸡鸡胚肝细胞中铁含量及含铁酶活性、基因表达和蛋白表达的影响。采用5×3两因子完全随机设计,铁水平分别为0、0.25、0.50、0.75、1.00 mmol/L,孵育时间分别为24、48和72 h,共形成15个组,每组6个重复。结果表明:1)铁水平、孵育时间及两者的互作对肝细胞铁含量有显著影响(P0.05)。24、48和72 h时,0.25、0.50、0.75、1.00 mmol/L铁水平组肝细胞中铁含量均显著高于0 mmol/L铁水平组(P0.05)。2)铁水平和孵育时间对肝细胞中胞琥珀酸脱氢酶(SDH)和细胞色素c氧化酶(COX)活性有显著影响(P0.05)。与0 mmol/L铁水平组相比,0.25、0.50、0.75和1.00 mmol/L铁水平组肝细胞中SDH活性显著降低(P0.05);24 h肝细胞中SDH活性显著高于48 h(P0.05),而72 h又显著高于24和48 h(P0.05)。与0 mmol/L铁水平组相比,0.75和1.00 mmol/L铁水平组肝细胞中COX活性显著提高(P0.05);24和48 h肝细胞中COX活性显著高于72 h(P0.05)。3)铁水平、孵育时间及两者的互作对肝细胞中SDH、过氧化氢酶(CAT)、COX7A2L和铁蛋白重链1(FTH1)的mRNA表达水平有显著影响(P0.05),铁水平及铁水平与孵育时间的互作对肝细胞中COX1的mRNA表达水平有显著影响(P0.05)。4)铁水平和孵育时间对肝细胞中COX1的蛋白表达水平有显著影响(P0.05),铁水平及铁水平与孵育时间的互作对肝细胞中FTH1的蛋白表达水平表达有显著影响(P0.05)。24和72 h肝细胞中COX1的蛋白表达水平显著高于48 h(P0.05),1.00 mmol/L铁水平组肝细胞中COX1的蛋白表达水平显著高于其他铁水平组(P0.05)。由此可见,铁水平和孵育时间可影响原代培养肉鸡鸡胚肝细胞中铁含量,SDH、CAT和COX的活性、基因表达,以及FTH1的基因表达。综合考虑以上指标,适宜铁的水平应为0.50 mmol/L,孵育时间为24 h。     

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。     

高表达线粒体融合蛋白2(MFN2)可抑制高BHBA活化的奶牛肝细胞NF-κB炎性通路

为研究线粒体融合蛋白2(mitofusin 2,MFN2)对高β-羟丁酸(β-hydroxybutyrate,BHBA)活化NF-κB炎性通路的影响,体外培养奶牛肝细胞,添加不同浓度(0.0,1.2,2.4,4.8 mmol/L)的BHBA,并转染过表达MFN2的腺病毒,运用Western blot和qRT-PCR技术检测NF-κB炎性通路关键分子的基因和蛋白表达。结果显示,随着BHBA浓度的增加,IKBα和NF-κB p65的磷酸化水平以及IL-1β、IL-6和TNFα的mRNA表达均显著升高,MFN2的基因和蛋白表达水平则显著降低;过表达MFN2后,显著抑制了高BHBA诱导的IKBα和NF-κB p65磷酸化水平及IL-1β、IL-6、TNFαmRNA表达水平的升高。结果表明,在奶牛肝细胞中过表达MFN2可以显著抑制高BHBA活化的NF-κB炎性通路。     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.

     

Heartworm in dogs in Canada in 1991

In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium.     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.

     

Heartworm in dogs in Canada in 1987

In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%).     

Heartworm in dogs in Canada in 1986

In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%).

Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada.