Erk activation is required for Nrf2 nuclear localization during pyrrolidine dithiocarbamate induction of glutamate cysteine ligase modulatory gene expression in HepG2 cells.

Pyrrolidine dithiocarbamate (PDTC) induction of the human glutamate cysteine ligase modulatory (GCLM) gene is dependent on activation of the mitogen-activated protein kinases (MAPKs) extracellular regulated kinase (Erk) and p38, and is not affected by protein kinase C (PKC) or PI3K inhibitors. Nrf2 binding to the electrophile response element (EpRE) located within the GCLM promoter is decreased after MAPK inhibition, suggesting that Nrf2 could be a downstream target of activated MAPK. To evaluate this hypothesis, a series of Nrf2 proteins harboring mutations in conserved consensus MAPK phosphorylation sites were developed and used in multiple functional assays. All mutated Nrf2 proteins tested interacted with the cytoplasmic repressor Keap1 in a manner indistinguishable from wild-type Nrf2. Furthermore, the mutant and wild-type Nrf2 proteins were similarly capable of transactivating an EpRE-containing GCLM/luciferase reporter transgene. Collectively these functional assays suggest that Nrf2 is not likely to be a direct downstream target of activated MAPK in vivo. However, treatment of HepG2 cells with MAPK inhibitors PD98059 and/or SB202190 prior to exposure to PDTC, reduced Nrf2 translocation to the nucleus, suggesting that MAPK-directed phosphorylation is a requirement for nuclear localization during PDTC induction of GCLM gene expression.     

Erythrocyte indicators of oxidative stress in gestational diabetes

Foetuses born to mothers with gestational diabetes are at increased risk of developing respiratory distress, foetal macrosomia, foetal anomalies and platelet hyperaggregability. High blood glucose level induces oxidative stress and decreases antioxidant defences. The present study discusses the possibility of lipid peroxidation and protein oxidation in both maternal and foetal erythrocytes as an indicator of oxygen radical activity. The level of lipid peroxidation and protein oxidation in erythrocytes was estimated in 20 mothers with gestational diabetes and their newborns. The maternal age varied between 19 and 42 y and foetal age ranged between 34 and 39 weeks. The proteolytic activities in the erythrocyte lysates obtained from mothers with gestational diabetes and their newborns were significantly greater [(mean ± SD) 24.41 ± 9.05 and 16.70 ± 3.36μM of amino groups/g haemoglobin, n = 20, respectively] than those from control group (10.18 ± 4.84 and 14.64 ± 6.21 μM amino groups/g haemoglobin, n = 15, respectively; p < 0:05 in both cases). Similarly erythrocyte malondialdehyde levels were significantly elevated in babies born to mothers with gestational diabetes (10.11 ±2.21 nM/g haemoglobin) when compared to controls (6.8 ± 3.75 nM/g haemoglobin) (p < 0:05). In the erythrocytes of mothers with gestational diabetes, malondialdehyde levels correlated significantly with glycated haemoglobin levels (p < 0:01). The results of this study indicate that the oxidative stress induced by gestational diabetes manifests as increased lipid peroxidation and protein oxidative damage in the erythrocytes of both mothers with gestational diabetes and their newborn infants.     

Antioxidant-rich diets improve cerebellar physiology and motor learning in aged rats

The free radical theory of aging predicts that reactive oxygen species are involved in the decline in function associated with aging. The present paper reports that diets supplemented with either spinach, strawberries or blueberries, nutritional sources of antioxidants, reverse age-induced declines in beta-adrenergic receptor function in cerebellar Purkinje neurons measured using electrophysiological techniques. In addition the spinach diet improved learning on a runway motor task, previously shown to be modulated by cerebellar norepinephrine. Motor learning is important for adaptation to changes in the environment and is thus critical for rehabilitation following stroke, spinal cord injury, and the onset of some neurodegenerative diseases. These data are the first to indicate that age-related deficits in motor learning and memory can be reversed with nutritional interventions.     

人体肝癌和正常肝脏细胞内硒与氧化应激机制的初步探讨

目的　探讨微量元素硒和氧化应激水平在肝癌发展中的作用。方法　采集了数例肝癌晚期切除样品及其癌旁正常组织 ,测定了正常肝脏组织和癌组织不同细胞器中硒的含量以及超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH -Px)、硫氧还蛋白还原酶 (TrxR)活性及谷胱甘肽 (GSH)和蛋白总巯基的含量。结果　Se在肝癌溶酶体 (P <0 0 5 )、微粒体 (P <0 0 5 )、细胞质中的含量高于正常肝组织 ,几种抗氧化酶酶的活性和巯基含量均高于正常肝。癌细胞中的Se含量要明显高于相应的癌旁周围正常肝细胞 ,尤其是细胞核、线粒体和细胞质。癌细胞线粒体、细胞质中几种抗氧化酶的活性以及巯基含量均高于相应的癌旁正常肝细胞。结论　癌细胞代谢旺盛 ,摄取更多的营养物质 ,从而造成周围正常细胞营养素的缺乏 ,抗氧化能力的下降 ,其机制还有待进一步研究     

孕期吸烟饮酒对仔鼠体格和神经发育的影响

目的:探讨孕期烟酒对子代神经发育的影响和机制。方法:建立烟酒复合因素所致小鼠胎儿宫内发育迟缓(IUGR)模型,观察小鼠自然分娩后子代的生长发育状态及神经行为功能,测定其体内抗氧化酶活性。结果:1.与对照组相比,烟酒处理组孕鼠体重增长和仔鼠体重、脏器重均显著降低(P<0.05);2.仔鼠早期反射时间明显延长(P<0.01),运动协调能力和自主活动能力显著降低(P<0.01);3.跳台及Y-迷宫实验中学习及记忆能力均降低(P<0.01,P<0.05);4.仔鼠脑细胞浆和线粒体丙二醛含量显著增高(P<0.05),超氧化物歧化酶、谷胱甘肽过氧化物酶、过氧化氢酶、谷胱甘肽S-转移酶活性皆呈不同程度降低。结论:孕期吸烟饮酒将显著影响子代的体格与神经发育,其机制与降低仔鼠的抗氧化能力和增加氧自由基损伤有关。     

维生素C对香烟烟雾的氧化应激作用的影响

目的　了解维生素C(VC)对香烟烟雾溶液 (CSS)作用下的大鼠淋巴细胞产生氧化应激的影响。方法　将香烟烟雾溶液作用于经VC预处理的大鼠淋巴细胞 ,用 2’ ,7’ -二乙酰二氯荧光素 (DCFH -DA)检测细胞内活性氧自由基 (ROS)水平 ,用彗星实验评价DNA的损伤状况 ,同时检测细胞内超氧化物歧化酶 (SOD)活性和脂质过氧化物(LPO)水平。结果　 8× 10 -3 支 /mlCSS作用下大鼠淋巴细胞内ROS和LPO水平增高 ,DNA损伤增强 ,SOD活性降低。用 5 0 μmol/LVC干预后 ,与相应非干预组相比细胞内ROS和LPO水平降低 ,DNA损伤减轻 ,SOD活性增强 ,且均有显著性差异。结论　 5 0 μmol/LVC能保护大鼠淋巴细胞 ,减轻CSS导致的氧化应激。     

坛紫菜硫酸多糖对60Co辐射引起的小鼠体内氧化应激的作用研究

应用生物化学的方法探讨在^60Co辐射条件下，坛紫菜硫酸多糖对小鼠体内氧化应激的抑制作用。结果表明，^60Co辐射能显著降低昆明种小鼠体内不同脏器组织匀浆SOD、GSH—Px的活性，引起脂质过氧化。坛紫菜硫酸多糖可提高辐射损伤后小鼠组织匀浆SOD、GSH—Px的活性，增强总抗氧化能力，减少脂质过氧化。     

妊娠高血压疾病患者氧化应激状态的改变

目的探讨妊娠高血压疾病患者氧化应激状态的改变情况。方法选取妊娠高血压疾病患者60例,其中妊娠高血压患者15例,轻度子痫前期患者15例,重度子痫前期患者30例。另取同期住院分娩的正常孕妇30例作为对照组。所有研究对象均测血清同型半胱氨酸、丙二醛、超氧化物歧化酶、谷胱甘肽过氧化物酶水平。结果妊娠高血压疾病组MDA水平为7.02±3.05 nmol/L,显著高于对照组5.16±2.79 nmol/L(P<0.01),妊娠高血压疾病组GSH-PX水平105.41±32.95 U/0.1 ml,明显低于对照组127.52±40.64 U/0.1 ml(P<0.05),两组SOD水平无显著差别。妊娠高血压疾病组Hcy为11.8±3.4μmol/L,显著高于对照组9.7±3.0μmol/L(P<0.01)。并且妊娠高血压疾病组Hcy与MDA呈正相关。结论妊娠高血压疾病患者由于氧化物质增加,抗氧化物质减少,氧化还原系统平衡失调,呈现氧化应激状态。     

有机磷类杀虫剂存在其他作用靶分子

目的：研究有机磷类杀虫剂对大鼠脑G蛋白偶联受体激酶2介导的毒蕈碱乙酰胆碱m2受体磷酸化的影响,揭示有机磷类杀虫剂存在的其他作用靶分子或作用途径.方法：制备亲和层析柱;利用亲和层析方法从大鼠脑中纯化毒蕈碱乙酰胆碱m2受体;将纯化的毒蕈碱乙酰胆碱m2受体或β-肾上腺素受体,G蛋白偶联受体激酶-2,[γ-p32]ATP与对氧磷（PO）、氧毒死蜱（CPO）共同保温,聚丙烯酰胺凝胶电泳分离蛋白,放射性自显影检测m2受体磷酸化结果.结果：氧毒死蜱完全抑制大鼠脑m2受体的磷酸化,其半数抑制浓度为（IC50）70μmol/L;对氧磷不抑制m2受体的磷酸化;氧毒死蜱和对氧磷都不抑制β-肾上腺素受体的磷酸化.结论：氧毒死蜱有选择性地抑制大鼠脑m2受体的磷酸化,说明某些有机磷杀虫剂的毒性作用存在其他靶分子或作用途径.