敲除Nrf2促进高脂饮食诱导小鼠肝脏NF-kB的活化

目的：氧化应激和炎症反应是NASH进展的关键因素,同时二者之间存在着密切关系,而转录因子Nrf2和NF-kB分别是氧化应激和炎症信号通路的关键调控靶点,因此,研究Nrf2对高脂饮食诱导小鼠肝脏NF-kB信号通路的影响,对探讨NASH进展具有重要的意义。方法：雄性野生型（WT）和Nrf2基因敲除（Nrf2-/-）ICR小鼠各10只,随机分为WT对照组（Control）、Nrf2-/-对照组（KO）、WT高脂饮食组（HFD）和Nrf2-/-高脂饮食组（KOHFD）（n=5）。喂养8周后,观察肝脏光镜下改变,检测肝脏GSH、MDA、TNFα和IL-6水平。Western-Blot检测肝脏NF-kB蛋白表达水平,观察敲除Nrf2对肝脏NF-kB活性作用的影响。结果：1.光镜下观察,Control组与KO组小鼠肝脏结构无明显变化,HFD组小鼠肝脏呈现大片脂肪沉积和炎症细胞浸润,KOHFD组小鼠肝脏则呈现明显的大泡性变性,且炎症细胞浸润较HFD组明显加重;2.与Control组相比,KO组小鼠肝脏MDA轻度升高,GSH轻度降低,但无明显差异,而HFD组和KOHFD组小鼠肝脏MDA显著升高（P〈0.05）,GSH显著降低（P〈0.05）,且KOHFD组MDA明显高于HFD组（P〈0.05）,GSH明显低于HFD组（P〈0.05）。3.ELISA结果显示,与Control组相比,KO组小鼠肝脏TNFα和IL-6分泌轻度增加,而HFD组和KOHFD组小鼠肝脏TNFα与IL-6水平显著升高（P〈0.05）,且KOHFD组小鼠肝脏TNFα与IL-6显著高于HFD组（P〈0.05）;4.Western-Blot结果显示,Control组和KO组之间无明显差异,而KOHFD组和HFD组小鼠肝脏胞核NF-kB蛋白表达水平显著升高,且KOHFD组高于HFD组。结论：敲除Nrf2可以显著加重高脂饮食诱导的小鼠肝脏氧化应激水平,进而促进NF-kB的活化,从而为通过以Nrf2为靶点治疗NASH提供重要的实验依据。     

杨梅素对高脂喂养小鼠代谢及自发活动节律的影响研究

摘要 目的：探讨杨梅素对高脂喂养小鼠代谢情况及自发活动节律的影响。方法：6周龄清洁级C57BL/6雄性小鼠15只,随机分为普通饲料组（CON）、高脂饲料组（HFD）、高脂饲料+杨梅素组100 mg /（kg?d）组（HFD+MYR）。从干预第10周开始使用Clocklab生物节律采集分析系统记录三组小鼠自发活动数据。干预第13周结束,检测三组小鼠体重、血脂数据。结果：与CON组相比,HFD组体重、甘油三酯、总胆固醇、低密度脂蛋白均显著升高（P<0.001）,高密度脂蛋白显著降低（P<0.001）,活动峰值时相（Activity phase）显著后移（P<0.001）,自发活动量中值（Activity mesor）和总自发活动量（Total counts）明显增加（P<0.05）,HFD+MYR组体重和低密度脂蛋白无明显变化（P>0.05）,甘油三酯、总胆固醇均显著升高（P< 0.01）,高密度脂蛋白显著降低（P<0.01）,活动峰值时相显著后移（P<0.001）,自发活动量中值和总自发活动量无明显变化（P>0.05）。与HFD组相比,HFD+MYR组体重、甘油三酯、总胆固醇、低密度脂蛋白明显降低（P<0.05）,高密度脂蛋白明显升高（P<0.05）,活动峰值时相明显前移（P<0.05）,自发活动量中值和总自发活动量明显减少（P<0.05）。结论：杨梅素可改善高脂喂养小鼠的代谢状态及减轻小鼠自发活动节律紊乱。     

毒毛花苷通过Nrf2抑制子宫内膜癌细胞增殖活性

摘要 目的：通过研究毒毛花苷对核因子2相关因子2 (nuclear factor erythroid 2-related factor 2, Nrf2)的抑制作用,深入探讨其抑制子宫内膜癌细胞增殖的作用机制。方法：（1）采用细胞增殖实验观察不同浓度的毒毛花苷对Ishikawa细胞增殖的影响;（2）通过克隆形成实验观察毒毛花苷对Ishikawa细胞增殖的作用;（3）采用蛋白免疫印迹法检测经毒毛花苷处理后,Ishikawa细胞Nrf2蛋白表达水平的变化。结果：经毒毛花苷处理后,Ishikawa细胞增殖受到显著抑制且呈剂量依赖性。Nrf2蛋白表达下调。结论：毒毛花苷可能通过下调Nrf2蛋白水平,从而抑制子宫内膜癌的恶性生物学行为。     

双硫仑治疗小鼠肥胖的安全性和有效性评价

摘要 目的：观察双硫仑治疗小鼠肥胖的安全性和有效性。方法：取6周龄C57BL/6J雄性小鼠10只,高脂饲料诱导肥胖后,随机分为双硫仑组（双硫仑玉米油溶液,300 mg/(kg?d）和对照组（等量玉米油）,每组5只小鼠。每日灌胃给药1次,连续2周,期间仍给与高脂饲料。监测小鼠食物消耗量和体重。给药结束后取小鼠血清、附睾白色脂肪垫、肩胛间区棕色脂肪和肝脏。白色、棕色脂肪和肝脏进行HE染色,观察细胞形态。电镜下观察棕色脂肪细胞内的脂滴和线粒体。Realtime-qPCR法检测棕色脂肪组织中Ucp1、Fabp4、Prdml6和Cidea的mRNA相对表达量,Western blot法检测Ucp1的蛋白表达量。检测血清中转氨酶ALT和AST含量。取8周龄C57BL/6J雄性小鼠10只,随机分为双硫仑组（双硫仑300 mg/(kg?d）和对照组（等量玉米油）,每日灌胃1次,连续2周。给药结束后进行棕色脂肪和肝脏HE染色并检测血清中ALT和AST含量。取8周龄C57BL/6J雄性小鼠10只,随机分为双硫仑组（双硫仑300 mg/(kg?d）和对照组（等量玉米油）,每日灌胃1次,连续4周,进行肝脏HE染色并检测血清中ALT和AST含量。取孕13.5天的C57BL/6J胚胎小鼠,进行成纤维细胞原代培养,分为双硫仑组（双硫仑5 mg/L）和对照组（等量DMSO）并诱导分化为棕色脂肪细胞。分化8天后进行油红O染色,观察脂滴形成情况,检测Ucp1、Fabp4、Prdml6和Cidea的mRNA相对表达量和Ucp1的蛋白表达量。结果：肥胖小鼠给药过程中,双硫仑组和对照组的进食量及体重变化并无明显差别（P＞0.05）。给药结束后,两组白色脂肪细胞大小无明显差别。双硫仑组小鼠棕色脂肪细胞直径和细胞内脂滴明显增大（P＜0.05）,脂滴数量、线粒体形态及数量无明显差别（P＞0.05）。双硫仑组小鼠棕色脂肪中Cidea和Prdm16的mRNA表达减少（P＜0.05）。正常体重小鼠双硫仑给药2周后棕色脂肪细胞脂滴也增大。细胞实验结果显示,双硫仑组脂滴形成明显减少,Ucp1、Cidea、Prdm16的mRNA表达明显减少（P<0.05）;Ucp1的蛋白表达明显减少（P<0.05）。肥胖与正常小鼠双硫仑给药2周后均出现明显的肝细胞水肿,血清中ALT和AST升高（P<0.05）,正常小鼠给药4周后仍有明显肝细胞水肿,ALT和AST升高（P<0.05）。结论：短期使用双硫仑对饮食诱导的肥胖小鼠无明显减肥作用;双硫仑在体内、外均可抑制小鼠棕色脂肪细胞的分化。短期使用双硫仑可引起肝损害。双硫仑用于减肥治疗的安全性及有效性尚不够理想。     

OSBPL3在代谢相关脂肪性肝病中的作用及机制研究

摘要 目的：探究氧化固醇结合蛋白类似物3（Oxysterol Binding Protein-like 3,OSBPL3）在代谢相关脂肪性肝病中的作用及可能机制。方法：建立肝脏特异性沉默OSBPL3小鼠模型和空载体对照组,分别予以普食和高脂喂养12周。分为正常对照组、OSBPL3沉默组、肥胖对照组、肥胖OSBPL3沉默组。观察小鼠一般情况,Real-time PCR检测脂质合成基因及脂质分解基因mRNA水平,western blot检测Akt/mTOR通路关键蛋白的表达。人HepG2细胞株给予不同浓度油酸（oleic acid,OA）处理,观察油红O染色的变化,western blot检测OSBPL3表达水平。结果：正常对照组与OSBPL3沉默组小鼠各项指标相比无统计学差异（P＞0.05）;与对照组相比,肥胖对照组及肥胖OSBPL3沉默组体质量、内脏脂肪及内脏脂肪指数较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组体质量、内脏脂肪及内脏脂肪指数较低（P＜0.05）。与对照组相比,肥胖对照组及肥胖OSBPL3沉默组总胆固醇(Total cholesterol,TC)、甘油三酯(triglycerides,TG)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组TC、TG、LDL-C及HDL-C较低（P＜0.05）。与正常对照组与OSBPL3沉默组小鼠SREBP-1C、FAS及PPARα表达水平相比无统计学差异（P＞0.05）;与对照组相比,肥胖对照组及肥胖OSBPL3沉默组SREBP-1C、FAS较高,PPARα表达水平较低（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组SREBP-1C、FAS表达水平较低,PPARα表达水平较高（P＜0.05）。与对照组相比,肥胖对照组Akt及mTOR磷酸化表达水平较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组Akt及mTOR磷酸化表达水平较低（P＜0.05）。随着OA作用浓度的升高,油红O染色逐渐加深。与0 μmol/L油酸相比,油酸以剂量依赖性方式增加HepG2细胞OSBPL3 mRNA水平（P<0.05）。结论：OSBPL3能够调控脂质代谢的表达,可能通过调控Akt/mTOR信号通路发挥生物学功能,有望为研究NAFLD疾病发生发展及治疗提供参考依据。     

漏芦醇提取物对小鼠乳腺上皮细胞氧化损伤的缓解作用

摘要 目的：探讨漏芦乙醇提取物（RUEE）对脂多糖（LPS）诱导的小鼠乳腺上皮细胞氧化损伤发挥保护作用。方法：采用体外培养的小鼠乳腺上皮细胞系 HC11 为模型,首先利用MTT法筛选RUEE的最佳作用浓度及检测LPS和RUEE对细胞活力的影响,然后用1 μg?mL^-1 LPS单独处理,20、40、80 μg?mL^-1的RUEE与 1 μg?mL^-1 LPS 共处理 HC11细胞,检测氧化应激相关指标、抗氧化相关基因mRNA和蛋白表达的变化。结果：细胞活力实验确定20、40、80 μg?mL^-1的RUEE作为后续试验的添加浓度。LPS诱导可显著提高HC11细胞内丙二醛（MDA）含量、一氧化氮（NO）水平、一氧化氮合酶（iNOS）活性（P＜0.05）;明显降低超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPx）、过氧化氢酶（CAT）的活性和总抗氧化能力（T-AOC）（P＜0.05）;显著抑制核因子E2相关因子2（Nrf2）、血红素氧合酶1（HO-1）、NAD(P)H醌氧化还原酶1（NQO1）的mRNA及蛋白表达（P＜0.05）。20、40、80 μg?mL^-1的RUEE预处理后可明显下调LPS诱导的HC11细胞内MDA含量、NO水平及iNOS活性（P＜0.05）;显著提高SOD、GPx、CAT的活性及T-AOC（P＜0.05）;显著上调Nrf2、HO-1、NQO1 mRNA和蛋白表达（P＜0.05）。结论：RUEE可以有效减轻LPS诱导的乳腺上皮细胞氧化损伤,这可能与RUEE能激活乳腺上皮细胞Nrf2进而促进抗氧化基因的表达有关。     

虎杖苷对老年小鼠术后认知功能障碍及海马氧化应激和神经炎症的影响

摘要 目的：探讨虎杖苷对老年小鼠术后认知功能障碍及海马氧化应激和神经炎症的影响。方法：C57BL/6J雄性老年小鼠,18月龄,体重24~28 g,随机分为4组：假手术组（Sham组）、术后认知功能障碍组（POCD组）、低剂量虎杖苷组（PD1组）、高剂量虎杖苷组（PD2组）。Sham组老年小鼠仅接受水合氯醛麻醉,不行外科手术;POCD组老年小鼠接受腹部手术以制备POCD老年动物模型;PD1组小鼠制备POCD模型,并于术后即刻、24 h和48 h分别腹腔注射低剂量虎杖苷25 mg/kg;PD2组小鼠制备POCD模型,并于术后即刻、24 h和48 h分别腹腔注射高剂量虎杖苷50 mg/kg。使用Morris水迷宫行为学实验评估老年小鼠术后认知功能,使用Western blot法检测术后小鼠海马Nrf2、HO-1、HMGB1、Iba-1蛋白水平,检测海马活性氧（ROS）、丙二醛（MDA）、超氧化物歧化酶（SOD）含量以反映术后海马氧化应激水平。结果：（1）与Sham组比较,POCD组老年小鼠术后逃离潜伏期显著增加（P<0.05）,穿越平台次数和目标象限停留时间下降（P<0.05）,海马Nrf2和HO-1蛋白表达水平明显降低（P<0.05）,氧化应激产物ROS和MDA含量增加（P<0.05）,抗氧化酶SOD活性降低（P<0.05）,Iba-1和HMGB1蛋白表达水平增加（P<0.05）;（2）与POCD组比较,PD1组和PD2组小鼠术后逃离潜伏期缩短（P<0.05）,穿越平台次数和目标象限停留时间增多（P<0.05）,海马Nrf2和HO-1蛋白表达水平升高（P<0.05）,ROS和MDA含量减少（P<0.05）,SOD活性增加（P<0.05）,Iba-1和HMGB1蛋白表达减少（P<0.05）。结论：虎杖苷可减轻老年小鼠术后认知功能损伤,缓解术后海马氧化应激和神经炎症,其机制可能与促进Nrf2/HO-1信号通路有关。     

miR-19通过Keap-Nrf2/HO-1信号通路对卵巢癌细胞增殖的影响

摘要 目的：研究卵巢癌组织和细胞中miR-19的表达,探讨其异常表达对卵巢癌细胞Kelch样环氧氯丙烷相关蛋白-1（Kelch-like epichlorohydrin-associated protein1,Keap1）--核因子E2相关因子2（nuclearfactor-E2-relatedfactor2,Nrf2） /血红素氧合酶-1（heme oxygenase1,HO-1）信号通路及卵巢癌细胞增殖的影响。方法：回顾性收集2019年1月至2020年12月于我院就诊的患者经病理切片诊断为卵巢癌上皮细胞的手术标本30例,卵巢良性肿瘤标本30例,正常卵巢组织标本30例。免疫组化检测不同标本中Keap1、Nrf2、HO-1的表达,检测卵巢组织及细胞中miR-19、Keap1、Nrf2、HO-1的mRNA表达水平,及卵巢癌细胞中Keap1、Nrf2、HO-1的蛋白表达水平。在OVCAR-3细胞中沉默miR-19后,Western Blot检测细胞内Keap1、Nrf2、HO-1蛋白表达水平,收集沉默miR-19,对照组,沉默Nrf2、对照组的OVCAR-3细胞,继续培养0 h、24 h、48 h后,检测细胞增殖和凋亡。结果：Keap1蛋白在卵巢癌组织中的阳性表达显著低于良性卵巢肿瘤组织及正常卵巢组织;Nrf2和HO-1蛋白在卵巢癌组织中的阳性表达显著低于良性卵巢肿瘤组织及正常卵巢组织（P＜0.05）;沉默miR-19抑制其表达后,细胞内Keap1 mRNA、蛋白表达水平明显升高,Nrf2、HO-1 mRNA表达水平无明显变化,蛋白表达水平明显降低（P＜0.05）;沉默miR-19 组、沉默Nrf2组与转染阴性对照组相比,增殖能力明显降低,凋亡能力明显升高（P＜0.05）。结论：卵巢癌细胞中,miR-19表达水平升高,可通过调控Keap1-Nrf2/HO-1信号通路影响卵巢癌细胞的增值、凋亡能力。     

黄芪水提取物减轻高脂饮食引起的小鼠肥胖

目的:研究黄芪水提取物(Astragalus radix extract,ARE)对高脂饮食(High fat diet,HFD)引起的小鼠肥胖的作用及可能机制。方法:将30只C57 BL/6小鼠随机分为正常喂养组(ND组,n=10)、高脂喂养组(HFD组,n=10)和高脂喂养+黄芪水提取物处理组(ARE组,n=10)。记录三组小鼠体重及食物摄入。在喂养16周时,对小鼠附睾白色脂肪称重,并进行HE染色观察脂肪细胞大小;对小鼠肝脏进行进行HE染色观察肝脏脂肪变性情况。应用ELISA方法检测血清瘦素及脂联素水平。应用Western Blot检测脂肪组织过氧化物酶体增殖物激活受体γ(Peroxisome proliferator activated receptorγ,PPARγ)表达。结果:1与ND组相比,HFD组体重及热量摄入均显著增加,表明肥胖模型建立成功;ARE处理组的体重较HFD组显著下降,但其热量摄入与HFD组相当。2与ND组相比,HFD组白色脂肪组织重量增加、脂肪细胞增大、肝细胞出现显著脂肪变性;ARE处理组上述指标较HFD组明显改善。3与ND组相比,HFD组瘦素水平升高、脂联素水平下降;ARE处理组与HFD组相比,瘦素水平降低、脂联素水平升高。4与ND组相比,HFD组PPARγ表达显著增加,而ARE处理组较HFD组PPARγ表达下降。结论:黄芪水提取物可能通过抑制PPARγ减轻高质饮食引起的肥胖。     

紫檀芪调节Keap-1/Nrf2/HO-1信号通路对非酒精性脂肪肝大鼠氧化应激和细胞凋亡的影响

摘要 目的：研究紫檀芪调节Kelch样ECH关联蛋白1（Keap-1）/核因子E2相关因子2（Nrf2）/血红素加氧酶-1（HO-1）信号通路对非酒精性脂肪肝（NAFLD）大鼠氧化应激和细胞凋亡的影响。方法：将60只SD大鼠随机分为对照组、模型组、紫檀芪低剂量组（30 mg/kg）、紫檀芪高剂量组（60 mg/kg）、紫檀芪（60 mg/kg）+N-（4-（2,3-二氢-1-（2''-甲基苯甲酰）-1H-吲哚-5-基）-5-甲基-2-噻唑基）-1,3-苯并二氧唑-5-乙酰胺（ML385）（30 mg/kg）组，每组12只。模型组与药物干预组大鼠以高脂饲料饲养诱导NAFLD模型，对照组大鼠以普通饲料饲养，各组连续喂养12周。以紫檀芪和ML385分组处理14 d后（对照组以等剂量生理盐水处理），检测各组大鼠脂代谢指标[三酰甘油（TG）、总胆固醇（TC）及游离脂肪酸（FFA）水平]、肝指数、肝功能指标[谷丙转氨酶（ALT）及谷草转氨酶（AST）]水平、血清白细胞介素（IL）-17、IL-6、IL-10、氧化应激指标[丙二醛（MDA）、超氧化物歧化酶（SOD）及过氧化氢酶（CAT）]水平；原位末端标记法（TUNEL）染色检测各组大鼠肝细胞凋亡率；蛋白免疫印迹法检测各组大鼠肝组织凋亡相关蛋白及Keap-1/Nrf2/HO-1通路相关蛋白表达。结果：与对照组相比，模型组大鼠血清IL-10、SOD及CAT水平、肝组织Nrf2、HO-1、Bcl-2表达水平显著降低（P＜0.05），TG、TC及FFA水平、肝指数、ALT及AST水平、血清IL-17、IL-6、MDA水平、肝细胞凋亡率、肝组织Keap-1及Bax表达水平显著升高（P＜0.05）。与模型组相比，紫檀芪低、高剂量组大鼠血清IL-10、SOD及CAT水平、肝组织Nrf2、HO-1、Bcl-2表达水平均升高（P＜0.05），TG、TC及FFA水平、肝指数、ALT及AST水平、血清IL-17、IL-6、MDA水平、肝细胞凋亡率、肝组织Keap-1、Bax表达水平均降低（P＜0.05）；与紫檀芪低剂量组相比，紫檀芪高剂量组大鼠血清IL-10、SOD及CAT水平、肝组织Nrf2、HO-1、Bcl-2表达水平升高（P＜0.05），TG、TC及FFA水平、肝指数、ALT及AST水平、血清IL-17、IL-6、MDA水平、肝细胞凋亡率、肝组织Keap-1及Bax表达水平降低（P＜0.05）；与紫檀芪高剂量组相比，紫檀芪+ML385组大鼠血清IL-10、SOD及CAT水平、肝组织Nrf2、HO-1、Bcl-2表达水平降低（P＜0.05），TG、TC及FFA水平、肝指数、ALT及AST水平、血清IL-17、IL-6、MDA水平、肝细胞凋亡率、肝组织Bax表达水平升高（P＜0.05）。结论：紫檀芪可能通过激活Keap-1/Nrf2/HO-1信号通路，改善NAFLD大鼠脂代谢水平，调节炎症反应及氧化应激，减轻肝组织脂肪变性及细胞凋亡。     

The inflammatory profile and liver damage of a sucrose-rich diet in mice

It is still unclear if an isoenergetic, sucrose-rich diet leads to health consequences.AimsTo investigate the effects of excessive sucrose within an isoenergetic diet on metabolic parameters in male C57BL/6 mice.MethodsAnimals were fed a control diet (10% fat, 8% sucrose — SC group), a high-sucrose diet (10% fat, 32% sucrose — HSu group), a high-fat diet (42% fat, 8% sucrose — HF group) or a high-fat/high-sucrose diet (42% fat, 32% sucrose — HF/HSu group) for 8 weeks.ResultsMice fed HF and HF/HSu diets gained more body mass (BM) and more body adiposity than SC- or Hsu-fed mice. Despite the unchanged BM and adiposity indices, HSu mice presented adipocyte hypertrophy, which was also observed in the HF and HF/HSu groups (P<.0001). The HF, HSu and HF/HSu mice were glucose intolerant and had elevated serum insulin levels (P<.05). The levels of leptin, resistin and monocyte chemotactic protein-1 increased, while the serum adiponectin decreased in the HF, HSu and HF/HSu groups (P<.05). In the adipose tissue, the HF, HSu and HF/HSu groups showed higher levels of leptin expression and lower levels of adiponectin expression in comparison with the SC group (P<.05). Liver steatosis was higher in the HF, HSu and HF/HSu groups than in the SC group (P<.0001). Hepatic cholesterol was higher in the HF and HF/HSu groups, while hepatic TG was higher in the HSu and HF/HSu groups (P<.05). In hepatic tissue, the sterol receptor element-binding protein-1c expression was increased in the HF, HSu and HF/HSu groups, unlike the peroxisome proliferator-activated receptor-alpha expression that decreased in the HF, HSu and HF/HSu groups in comparison with the SC group (P<.05).ConclusionA sucrose-rich diet does not lead to a state of obesity but has the potential to cause changes in the adipocytes (hypertrophy) as well as glucose intolerance, hyperinsulinemia, hyperlipidemia, hepatic steatosis and increases in the number of inflammatory cytokines. The deleterious effects of a sucrose-rich diet in an animal model, even when the sucrose replaces starch isocalorically in the feed, can have far-reaching consequences for health.     

Lipoic acid administration prevents nonalcoholic steatosis linked to long-term high-fat feeding by modulating mitochondrial function

Nonalcoholic steatosis is an important hepatic complication of obesity linked to mitochondrial dysfunction and insulin resistance. Furthermore, lipoic acid has been reported to have beneficial effects on mitochondrial function. In this study, we analyzed the potential protective effect of lipoic acid supplementation against the development of nonalcoholic steatosis associated with a long-term high-fat diet feeding and the potential mechanism of this effect. Wistar rats were fed on a standard diet (n=10), a high-fat diet (n=10) and a high-fat diet supplemented with lipoic acid (n=10). A group pair-fed to the latter group (n=6) was also included. Lipoic acid prevented hepatic triglyceride accumulation and liver damage in rats fed a high-fat diet (?68%±11.3% vs. obese group) through the modulation of genes involved in lipogenesis and mitochondrial β-oxidation and by improving insulin sensitivity. Moreover, this molecule showed an inhibitory action on electron transport chain complexes activities (P<.01–P<.001) and adenosine triphosphate synthesis (P<.05), and reduced significantly energy efficiency. By contrast, lipoic acid induced an increase in mitochondrial copy number and in Ucp2 gene expression (P<.001 vs. obese). In summary, this investigation demonstrated the ability of lipoic acid to prevent nonalcoholic steatosis induced by a high-fat intake. Finally, the novelty and importance of this study are the finding of how lipoic acid modulates some of the mitochondrial processes involved in energy homeostasis. The reduction in mitochondrial energy efficiency could also explain, at least in part, the beneficial effects of lipoic acid not only in fatty liver but also in preventing excessive body weight gain.     

Polychlorinated biphenyl 153 is a diet-dependent obesogen that worsens nonalcoholic fatty liver disease in male C57BL6/J mice

BackgroundPolychlorinated biphenyls (PCBs) are persistent environmental pollutants that are detectable in the serum of all American adults. Amongst PCB congeners, PCB 153 has the highest serum level. PCBs have been dose-dependently associated with obesity, metabolic syndrome and nonalcoholic fatty liver disease (NAFLD) in epidemiological studies.ObjectiveThe purpose of this study is to determine mechanisms by which PCB 153 worsens diet-induced obesity and NAFLD in male mice fed a high-fat diet (HFD).MethodsMale C57BL6/J mice were fed either control or 42% milk fat diet for 12 weeks with or without PCB 153 coexposure (50 mg/kg ip ×4). Glucose tolerance test was performed, and plasma and tissues were obtained at necropsy for measurements of adipocytokine levels, histology and gene expression.ResultsIn control diet-fed mice, addition of PCB 153 had minimal effects on any of the measured parameters. However, PCB 153 treatment in high-fat-fed mice was associated with increased visceral adiposity, hepatic steatosis and plasma adipokines including adiponectin, leptin, resistin and plasminogen activator inhibitor-1 levels. Likewise, coexposure reduced expression of hepatic genes implicated in β-oxidation while increasing the expression of genes associated with lipid biosynthesis. Regardless of diet, PCB 153 had no effect on insulin resistance or tumor necrosis factor alpha levels.ConclusionPCB 153 is an obesogen that exacerbates hepatic steatosis, alters adipocytokines and disrupts normal hepatic lipid metabolism when administered with HFD but not control diet. Because all US adults have been exposed to PCB 153, this particular nutrient–toxicant interaction potentially impacts human obesity/NAFLD.     

Chronic intermittent hypoxia causes hepatitis in a mouse model of diet-induced fatty liver

Obstructive sleep apnea (OSA) causes chronic intermittent hypoxia (CIH) during sleep. OSA is associated with nonalcoholic steatohepatitis (NASH) in obese individuals and may contribute to progression of nonalcoholic fatty liver disease from steatosis to NASH. The purpose of this study was to examine whether CIH induces inflammatory changes in the liver in mice with diet-induced hepatic steatosis. C57BL/6J mice (n = 8) on a high-fat, high-cholesterol diet were exposed to CIH for 6 mo and were compared with mice on the same diet exposed to intermittent air (control; n = 8). CIH caused liver injury with an increase in serum ALT (461 +/- 58 U/l vs. 103 +/- 16 U/l in the control group; P < 0.01) and AST (637 +/- 37 U/l vs. 175 +/- 13 U/l in the control group; P < 0.001), whereas alkaline phosphatase and total bilirubin levels were unchanged. Histology revealed hepatic steatosis in both groups, with mild accentuation of fat staining in the zone 3 hepatocytes in mice exposed to CIH. Animals exposed to CIH exhibited lobular inflammation and fibrosis in the liver, which were not evident in control mice. CIH caused significant increases in lipid peroxidation in serum and liver tissue; significant increases in hepatic levels of myeloperoxidase and proinflammatory cytokines IL-1beta, IL-6, and CXC chemokine MIP-2; a trend toward an increase in TNF-alpha; and an increase in alpha1(I)-collagen mRNA. We conclude that CIH induces lipid peroxidation and inflammation in the livers of mice on a high-fat, high-cholesterol diet.     

Effect of Octreotide on Hepatic Steatosis in Diet-Induced Obesity in Rats

Background

Non-alcoholic fatty liver disease (NAFLD) caused by liver lipid dysregulation is linked to obesity. Somatostatin (SST) and its analogs have been used to treat pediatric hypothalamic obesity. However, the application of such drugs for the treatment of NAFLD has not been evaluated.

Objective

This study aimed to investigate the expression levels of important regulators of hepatic lipid metabolism and the possible effect of the SST analog octreotide on these regulators.

Methods

SD rats were assigned to a control group and a high-fat diet group. Obese rats from the high-fat diet group were further divided into the obese and octreotide-treated groups. The body weight, plasma SST, fasting plasma glucose (FPG), insulin, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and free fatty acid (FFA) levels were measured. Hepatic steatosis was evaluated based on the liver TG content, HE staining and oil red O staining. The SREBP-1c, ACC1, FAS, MTP, apoB and ADRP expression levels in the liver were also determined by RT-PCR, qRT-PCR, western blot or ELISA.

Results

The obese rats induced by high-fat diet expressed more SREBP-1c, FAS and ADRP but less MTP protein in the liver than those of control rats, whereas octreotide intervention reversed these changes and increased the level of apoB protein. Compared to the control group, obese rats showed increased liver ACC1, SREBP-1c and apoB mRNA levels, whereas octreotide-treated rats showed decreased mRNA levels of apoB and SREBP-1c. This was accompanied by increased body weight, liver TG contents, FPG, TG, TC, LDL-C, FFA, insulin and derived homeostatic model assessment (HOMA) values. Octreotide intervention significantly decreased these parameters. Compared to the control group, the obese group showed a decreasing trend on plasma SST levels, which were significantly increased by the octreotide intervention.

Conclusion

Octreotide can ameliorate hepatic steatosis in obese rats, possibly by decreasing hepatic lipogenesis and increasing TG export from hepatocytes.     

Genes of the antioxidant response undergo upregulation in a rodent model of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease encompasses a spectrum of hepatic pathologies ranging from simple fatty liver to an inflammatory state known as nonalcoholic steatohepatitis (NASH). NASH is also characterized by severe hepatic oxidative stress. The goal of this study was to determine whether genes of the antioxidant response are induced in rodent models of nonalcoholic fatty liver disease. To simulate simple fatty liver and NASH, respectively, male Sprague-Dawley rats were fed a high-fat (HF) or a methionine and choline-deficient (MCD) diet for 8 weeks. Key marker genes of the antioxidant response that are known to undergo upregulation via activation of Nuclear Factor Erythroid 2-Related Factor 2 were measured using the branched DNA signal amplification assay. Messenger RNA levels of the antioxidant response, including NAD(P)H:quinone oxidoreductase-1 (Nqo1), Glutamate cysteine ligase catalytic (Gclc), and Heme oxygenase-1 (Ho-1), were significantly induced in MCD rat liver but not in HF rat liver. Furthermore, Nqo1 protein expression and activity underwent significant upregulation in MCD rat liver but not in HF rat liver. These data strongly indicate that the pathology induced by the MCD dietary model of NASH results in upregulation of the antioxidant response in rats.