苏氨酸锌对糖尿病大鼠肝脏损伤的保护作用

目的：观察苏氨酸锌对链脲佐菌素(STZ)诱导的糖尿病大鼠肝脏的抗氧化性、肝功能等相关指标的影响,并探讨其可能的作用机制。方法：采用尾静脉注射链脲佐菌素法复制糖尿病大鼠模型。将造模成功的大鼠随机分为糖尿病对照组,二甲基双胍阳性对照组,苏氨酸锌低、中、高剂量组,另设同龄大鼠为正常对照组。检测并比较各组肝脏匀浆谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、一氧化氮合酶(NOS)、丙二醛(MDA)、一氧化氮(NO)、肝脏指数以及血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)、血清总蛋白(TP)等指标。结果：高剂量的苏氨酸锌对糖尿病大鼠的MDA、NO、SOD、GSH-Px、肝脏指数等指标有显著性改善作用(P＜0.05),并对ALT、AST、 AST/ALT、TP有一定的改善作用。结论：苏氨酸锌对糖尿病大鼠肝脏氧化损伤、肝功能有一定的保护作用。     

酵母源金属硫蛋白对慢性汞中毒小鼠氧化损伤的修复作用

探讨具有自主知识产权的两种酵母源金属硫蛋白（metallothionein,MT）亚型（MT-1和MT-2）对慢性汞中毒小鼠氧化损伤的修复作用。实验小鼠经氯化汞染毒,连续灌胃两种酵母源MT及二巯基丙磺酸钠（dimercaptopropansulfonate sodium,DMPS）28 d后测定小鼠体质量、全血汞含量及血清超氧化物歧化酶（superoxide dismutase,SOD）、谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）活力,丙二醛（malondialdehyde,MDA）含量及机体总抗氧化能力（total antioxidative capacity,T-AOC）。与正常对照组小鼠相比,模型对照组小鼠体质量显著下降（P＜0.05）,灌胃给药28 d后,两种酵母源MT亚型高剂量组小鼠体质量显著升高（P＜0.05）;各给药组小鼠血液、肝脏及肾脏汞含量显著低于模型对照组（P＜0.05）,两种酵母源MT亚型高剂量组的排汞效果显著优于DMPS组（P＜0.05）;各给药组小鼠血清中GSH-Px、SOD活力和MDA水平及总抗氧化能力接近正常对照组小鼠水平（P＞0.05）,其中酵母源MT高剂量组的作用效果最佳,且在改善机体T-AOC方面的效果优于DMPS组（P＜0.05）,酵母源MT-1亚型升高小鼠血清SOD活力和降低血清MDA含量的作用效果明显好于酵母源MT-2亚型。两种酵母源MT对慢性汞中毒小鼠具有良好的氧化损伤保护作用及排汞效果。     

Liver proteomic analysis of postpartum Holstein cows exposed to heat stress or cooling conditions during the dry period

Heat stress negatively affects cow performance, compromises immune function, and increases susceptibility to metabolic disorders, particularly during the dry period and as cows transition from gestation to lactation. Metabolic adaptations of the liver are critical for successful transition, yet it is unclear how heat stress affects metabolic pathways within the liver at the proteomic level. The objective of this study was to investigate the liver proteome of postpartum cows that were cooled or heat stressed during the dry period to gain insight into how protein expression is altered by prior heat stress and may contribute to performance and disease outcomes. During the dry period, cows were either housed in shaded barns with fans and water soakers [cooled group (CL); n = 5] or in shaded barns lacking these cooling devices [heat-stressed group (HT); n = 5]. Liver biopsies were collected at 2 d postpartum, and protein content was analyzed by label-free quantitative shotgun proteomics (nanoscale liquid chromatography coupled to tandem mass spectrometry). In the most comprehensive bovine liver proteomics analysis completed to date, we identified 3,270 proteins, 75 of which were differentially expressed between HT and CL cows (fold change ±1.2). The top pathways differing between HT and CL cows were oxidative phosphorylation, mitochondrial dysfunction, farnesoid X receptor/retinoid X receptor (FXR/RXR) activation, and the methylmalonyl pathway. Cooling cows during the dry period likely improves ATP production, reduces oxidative stress, and prevents excessive accumulation of hepatic triglycerides and cholesterol, which may contribute to greater milk yield and lower susceptibility to transition-related diseases.     

酵母源金属硫蛋白排汞及对汞致肝脏及机体氧化损伤的修复作用

目的:探讨两种酵母源金属硫蛋白(metallothioneins,MT)-1、MT-2对氯化汞急性汞中毒小鼠排汞及对汞致肝脏及机体氧化损伤的修复作用。方法:氯化汞急性汞中毒小鼠模型通过颈部皮下注射氯化汞生理盐水溶液构建,急性汞中毒小鼠经连续灌胃二巯基丙磺酸钠(dimercaptopropansulfonate sodium,DMPS)及不同剂量(0.16、0.40、0.80 mg/(kg·d))酵母源MT 14 d后,测定小鼠体质量、肝脏脏器系数、血液及肝脏Hg~(2+)的含量、血清谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活力、超氧化物歧化酶(superoxide dismutase,SOD)活力、机体总抗氧化能力(total antioxidative capacity,T-AOC)及丙二醛(malondialdehyde,MDA)含量和两项肝功能指示指标:谷丙转氨酶(alanine aminotransferase,ALT)及谷草转氨酶(aspartate transaminase,AST)活力。结果:相较于正常组小鼠,模型组小鼠体质量下降、肝脏脏器系数上升,差异具有统计学意义(P0.05);血液及肝脏Hg~(2+)含量显著上升(P0.05);血清GSH-Px、SOD活力及T-AOC显著降低(P0.05),MDA含量显著升高(P0.05);两项肝功能指标ALT及AST活力显著升高(P0.05)。经灌胃给药处理后,与模型组小鼠相比,酵母源MT中、高剂量处理组及二巯基丙磺酸钠阳性对照组小鼠体质量均显著上升(P0.05),并与正常组小鼠无显著性差异(P0.05);各给药处理组小鼠脏器系数均较模型组小鼠显著下降(P0.05)且呈一定的剂量-效应关系。各灌胃给药处理组小鼠血液及肝脏Hg~(2+)含量均不同程度下降;血清GSH-Px、SOD活力及T-AOC均不同程度回升,MDA含量及两项肝功能指标ALT及AST活力均不同程度降低。在0.16~0.80 mg/kg剂量范围内,高剂量酵母源MT给药效果最佳,与其他灌胃给药处理组差异显著(P0.05)。结论:两种酵母源MT对急性汞中毒小鼠具有良好的结合机体内游离Hg~(2+)及修复肝脏损伤及机体氧化损伤作用,且作用效果与给药剂量呈正相关。     

蓝莓黑醋栗枸杞决明子复合物对眼部细胞氧化应激损伤的保护作用

探讨了蓝莓黑醋栗枸杞决明子复合物（Blueberry,Blackcurrant,Medlar,Cassia Seed Complex,LHGJ）对丙酮醛（Methylglyoxal,MGO）诱导的人视网膜上皮细胞（Retinal Pigment Epithelium,APRE-19）氧化应激损伤的保护作用。以MGO诱导ARPE-19细胞氧化应激损伤建立细胞模型,给予不同质量浓度LHGJ复合物处理。利用CCK-8法检测细胞活力,采用荧光显微镜检测细胞活性氧（Reactive Oxygen Species,ROS）含量、采用酶联免疫法（Enzyme-linked Immunosorbent Assay,ELISE）测定一氧化氮（Nitric Oxide,NO）含量、比色法测定谷胱甘肽过氧化物酶（Glutathione Peroxidase,GSH-Px）及羟胺法测定超氧化物歧化酶（Superoxide Dismutase,SOD）活性。实验结果表明,ARPE-19细胞可经0.80 mmol/L MGO诱导氧化应激损伤模型。诱导ARPE-19细胞经0.10、1.00 μg/mL LHGJ复合物处理后,细胞活力增加23.03%与21.23%,具有高度显著差异（P<0.001）。0.01、0.10、10.00 μg/mL LHGJ复合物使ROS的荧光强度显著降低1.02、1.28、2.37倍（P<0.05）,0.01、0.10、10 μg/mL LHGJ复合物使NO的生成量显著降低13.24、15.23、16.24 μmol/g prot（P<0.05）;1.00、10.00 μg/mL LHGJ 复合物使SOD活性显著与极显著升高6.01、7.43 U/mg（P<0.05、P<0.01）;1.00与10.00 μg/mL LHGJ复合物显著增加了GSH-Px活力14.32及25.42 U/mg（P<0.05）。LHGJ 复合物对MGO导致的ARPE-19细胞氧化应激损伤具有保护作用,可为LHGJ进一步开发提供理论依据。     

真菌中氧胁迫调控因子AP-1研究进展

氧化应激是细胞应激反应的一种,在所有生物中都是保守进化的。应激反应的调控包括转录、翻译和翻译后修饰,决定生物体是否适应、存活、或者死亡。酵母中b-ZIP型激活蛋白(Yap)家族包括8个成员,Yap1是酵母Yap家族中首先发现的成员,具有DNA结合结构域和转录激活活性,在细胞的氧化应激中发挥着必不可少的作用。在氧化压力下,Yap1的活性增加。本文对近年来AP-1转录因子在真菌中的主要研究进展进行了综述,重点介绍了AP-1作为主要的氧化应激调节器参与的生物学应激反应、致病性及产生真菌毒素等,并介绍了AP-1在铁代谢、钴毒性、DNA损伤、耐药性中的功能。     

原花青素对糖尿病大鼠肾的保护作用

本文主要研究了原花青素(PC)对糖尿病大鼠肾脏的保护作用,并初步探讨其作用机制。实验中采用高脂高糖饲料喂养联合链脲佐菌素(STZ)损伤建立糖尿病大鼠模型。将造模大鼠按照体重随机分为模型组和实验组,同时设立正常组。实验组,每日腹腔注射原花青素150 mg/kg,其余2组腹腔注射等体积的生理盐水,连续给药4周后,检测血糖(BG)、总胆固醇(TC)、三酰甘油(TG)及肾脏组织中丙二醛(MDA)、蛋白羰基化(PCO)、超氧化物歧化酶(SOD)及过氧化氢酶(CAT)的活性,光镜观察肾组织结构。结果表明,与正常组相比,模型组TC、TG显著升高了4.02倍和6.88倍(p0.01),肾脏组织中的SOD活性降低27.88%,CAT活性降低了17.61%(p0.01),肾脏组织MDA、PCO含量显著升高了51.10%和81.36%(p0.01);与模型组相比,实验组大鼠血糖、TC和TG水平明显降低了50.84%、55.70%和70.52%(p0.01),肾脏组织中的SOD、CAT活性明显升高了26.05%和12.97%(p0.01),肾脏组织MDA、PCO含量显著降低到21.54%和11.86%(p0.01)。病理切片显示,PC保护可减轻STZ引起的肾小球萎缩等病理损伤。由结果可知,原花青素对糖尿病大鼠肾具有一定的保护作用,其机制可能与其抗氧化作用有关。     

Methionine supply alters mammary gland antioxidant gene networks via phosphorylation of nuclear factor erythroid 2-like 2 (NFE2L2) protein in dairy cows during the periparturient period

The periparturient period is the most critical period during the lactation cycle of dairy cows and is characterized by increased oxidative stress status. The objective of this experiment was to evaluate the effect of supplementing rumen-protected methionine on nuclear factor erythroid 2-like 2 (NFE2L2, formerly NRF2) protein and target gene expression in the mammary gland during the early postpartal period. Multiparous Holstein cows were used in a block design experiment with 30 cows per treatment. Treatments consisting of a basal control diet (control) or the basal diet plus rumen-protected methionine (methionine) were fed from d ?28 to 60 relative to parturition. Mammary tissue biopsies were harvested on d 21 postpartum from 5 cows per treatment. Compared with control, methionine increased dry matter intake, milk yield, and milk protein content. Among plasma parameters measured, methionine led to greater methionine and lower reactive oxygen metabolites. Compared with control, methionine supply resulted in greater mRNA abundance of the NFE2L2 target genes glutamate-cysteine ligase catalytic subunit (GCLC), glutamate-cysteine ligase modifier subunit (GCLM), glutathione reductase (GSR), glutathione peroxidase 1 (GPX1), malic enzyme 1 (ME1), ferrochelatase (FECH), ferritin heavy chain 1 (FTH1), and NAD(P) H quinone dehydrogenase 1 (NQO1) in the mammary tissue. In addition, methionine upregulated the mRNA abundance of NFE2L2, NFKB1, MAPK14 and downregulated KEAP1. The ratio of phosphorylated NFE2L2 to total NFE2L2 protein, and total heme oxygenase 1 (HMOX1) protein were markedly greater in response to methionine supply. In contrast, total protein abundance of Kelch-like ECH-associated protein 1 (KEAP1), which sequesters NFE2L2 in the cytosol and reduces its activity, was lower with methionine. Besides the consistent positive effect of methionine supply on systemic inflammation and oxidative stress status, the present data indicate a positive effect also on antioxidant mechanisms within the mammary gland, which are regulated, at least in part, via phosphorylation of NFE2L2 and its target genes. The exact mechanisms for these responses merit further study.     

Short communication: hydroperoxides in circulating lipids from dairy cows: implications for bioactivity of endogenous-oxidized lipids

This study was conducted to investigate the potential for increased oxidative stress of high- vs. average-producing dairy cows. Two experiments were performed using 11 and 13 Holstein cows (53 +/- 2 d postpartum). Lipohydroperoxides (LHP) were determined in serum lipids (experiment 1) and low-density lipoprotein (experiment 2) via oxidation of ferrous to ferric ions through LHP using thiocyanate as chromogen. In experiment 1, differing milk yield and milk energy output corresponded to different concentrations of LHP. In experiment 2, analysis of regression resulted in a significant relationship between milk yield and LHP. Phospholipids isolated from lipids with 6.5 microM of LHP evoked in monocytic cells a transient increase in superoxide formation, indicating inflammatory potential. The results show that high milk productivity can associate with oxidative stress indicated by oxidative modifications of circulating lipids and their changed bioactivity.     

叶黄素对铁过载大鼠氧化应激水平影响的实验研究

目的:铁是人体必需的微量元素之一,但机体内铁负荷过多可诱导氧化应激,造成细胞和组织损伤。本研究通过建立铁过载大鼠模型,探讨不同剂量叶黄素对其氧化应激水平的影响。方法:60只SD雄性大鼠随机分为5组,每组12只。正常对照组大鼠饲喂基础饲料(铁含量50 mg/kg),其他大鼠均饲喂高铁饲料(铁含量1 000 mg/kg),建立铁过载模型大鼠,同时随机分为高铁负荷组、高铁+叶黄素低剂量组(10 mg/kg·bw)、高铁+叶黄素中剂量组(20 mg/kg·bw)、高铁+叶黄素高剂量组(40 mg/kg·bw)。持续喂养6w后,测定血清铁蛋白、血清铁、肝组织铁及血清和肝匀浆中总超氧化物歧化酶(T-SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、丙二醛(MDA)等含量。结果:与正常对照组比较,高铁负荷组大鼠血清铁及血清铁蛋白含量均升高28%(P值均0.05),肝组织铁含量升高23%(P0.01)。与高铁负荷组大鼠比较,添加叶黄素低剂量、中剂量和高剂量的高铁负荷组大鼠血清铁、血清铁蛋白及肝组织铁含量均显著降低(P值均0.05),与正常对照组水平无显著差异(P值均0.05)。氧化应激水平分析显示,高铁负荷组大鼠血清GSH-Px活力和肝匀浆GSH-Px活力比正常对照组分别降低了12%和20%(P值均0.05)。中剂量叶黄素组大鼠血清GSH-Px及CAT活力比高铁负荷组分别提高了12%、32%(P值均0.05);高剂量叶黄素组肝匀浆GSH-Px活力比高铁负荷组大鼠提高了23%(P0.05)。与正常对照组比较,高铁负荷和高铁+低剂量叶黄素组肝匀浆T-SOD活力分别降低了20%和17%(P值均0.05)。而高剂量叶黄素组大鼠肝匀浆T-SOD活力与高铁负荷和高铁+低剂量叶黄素组大鼠相比分别提高了22%和19%(P值均0.05)。高铁负荷组大鼠肝匀浆CAT活力比正常组降低了19%(P0.05),比中剂量叶黄素组下降了22%(P0.05)。结论:铁负荷过载可降低机体多种抗氧化酶的活性,增加机体氧化应激水平;补充叶黄素可有效地减少高铁负荷损伤,提高抗氧化能力,较高剂量补充的效果可能更明显。     

小檗碱及其衍生物抑菌作用研究进展

小檗碱是从中草药黄连等植物中提取分离的一类异喹啉类生物碱,具有多种生物活性和药效,早已广泛应用于临床。但小檗碱生物利用度低、功能特性研究局限于医学应用。通过化学方法修饰或改造可制备一系列抑菌活性得到增强的衍生物。本文主要综述小檗碱及其衍生物的制备、抑菌作用和机理进展,并对小檗碱作为防腐剂或与壳聚糖等混合涂膜应用于蔬果防病、保鲜进行展望,以期为小檗碱尤其是小檗碱衍生物在食品中的保鲜作用研究提供一定的参考。