香菇多糖的免疫调节作用

研究香菇多糖(LTN)的免疫调节作用。结果表明,LTN1及5mg·kg^-1·d^-1×6,ip可促进正常小鼠由ConA(2.5mg·kg^-1)刺激的脾脏T淋巴细胞增殖反应。1,5及10mg·kg^-1·d^-1×8或5,ip能分别纠正由环磷酰胺(Cy,200mg·kg^-1和80mg·kg^-1,ip)诱导的免疫亢进或低下状态。此外,LTN(1,5和10mg·kg^-1·d^-1×6,ip),促使小鼠胸腺L3T4+(Th)和Lyt2+(Ts)细胞数减少,外周脾脏L3T4+和Lyt2+细胞数增加,腹腔巨噬细胞释出肿瘤坏死因子(TNF)也明显增加。这些作用均以LTN5mg·kg^-1·d^-1作用最佳。提示LTN可能通过影响T细胞及其亚型,促进TNF活性调节机体的免疫功能。     

映山红花总黄酮对盐酸异丙肾上腺素诱导大鼠心肌缺血的保护作用

目的观察映山红花总黄酮(TFR)对盐酸异丙肾上腺素诱导的实验性心肌缺血的保护作用。方法采用皮下(sc)注射盐酸异丙肾上腺素(Iso)(8 mg·kg^-1×2 d)诱导大鼠实验性心肌缺血模型,测定血清中MDA含量、GSH-PX活力、SOD及心肌组织中ATPase活性。同时行心肌组织病理组织学检查。结果TFR 30 mg·kg^-1显著降低血清中MDA的生成,30,15 mg·kg^-1及60,30 mg·kg^-1升高SOD,GSH-PX的活力,60,30 mg·kg^-1TFR可抑制心肌组织中Na⁺-K⁺-ATPase,Ca²⁺-Mg²⁺-AT-Pase,总ATPase活力的降低,TFR 60,30 mg·kg^-1能显著改善sc Iso后心肌病理损伤程度,降低其病理损伤评分。结论TFR对盐酸异丙肾上腺素诱导的实验性心肌缺血有保护作用,其机制可能与减少体内自由基生成、改善心肌能量代谢有关。     

利福平及异烟肼对家兔体内地西泮药代动力学的影响

用HPLC测定方法,研究了家兔多次ig利福平(100mg·kg^-1·d^-1×4)及异烟肼(50mg·kg^-1×4)后,对iv地西泮的药代动力学。结果表明,给药后利福平组肝微粒体细胞色素P-450含量增加98.1%,使地西泮的T_1/2β由98.77±19.38min减少到40.08±17.75min;AUC由143.52±41.41mg·min·L^-1减少到79.10±11.46mg·min·L^-1;CL由22.41±8.12ml·min^-1·kg^-1增加到43.96±10.38ml·kg^-1·min^-1。异烟肼组则表现出相反的作用。而利福平与异烟肼合用组对P-450含量及地西泮的动力学均无显著影响。提示利福平诱导家兔肝药酶的作用可加速地西泮的体内代谢过程,异烟肼抑制肝药酶减低地西泮的代谢。     

双环醇对四环素诱发小鼠急性脂肪肝的保护作用

研究双环醇对四环素诱发小鼠急性脂肪肝的影响。小鼠一次腹腔注射四环素(180 mg·kg^-1) 24 h后，收集血样和肝组织，采用生化法测定肝脏甘油三酯(triglyceride，TG)、胆固醇(cholesterol，CHO)、谷胱甘肽(glutathione，GSH)含量，以及血清脂质和转氨酶水平；光谱法测定小鼠线粒体脂肪酸β-氧化速率以及肝脏极低密度脂蛋白(very low density lipoprotein，VLDL，TG)分泌速率。结果表明，双环醇(150及300 mg·kg^-1)连续灌胃给药3次可以不同程度地保护四环素引起的小鼠肝脏TG和CHO升高以及血清谷丙转氨酶(alanine aminotransferase，ALT)、谷草转氨酶(aspartate aminotransferase，AST)升高和脂质异常。双环醇(300 mg·kg^-1)还可减轻四环素诱发小鼠肝脏丙二醛(malondialdehyde，MDA)生成增加和GSH水平降低，并能抑制肝线粒体脂肪酸β-氧化速率下降。双环醇(300 mg·kg^-1)可部分逆转四环素所致小鼠肝脏VLDL(TG)分泌速率的减少。由此可见，双环醇对四环素诱发小鼠急性脂肪肝具有明显的保护作用，其作用机制与保护肝线粒体β-氧化功能、改善肝脂蛋白分泌及转运以及抑制肝脏脂质过氧化密切相关。     

苦参碱联合甘草甜素在四氯化碳慢性肝损伤中的保护作用及机制

摘 要 目的：考察苦参碱联合甘草甜素在四氯化碳（CCl₄）慢性肝损伤中的保护作用,并从能量代谢及CYP酶的角度探讨其保护机制。方法: 建立CCl₄慢性肝损伤模型,通过考察血清ALT、AST观察两药及其联合用药在慢性肝损伤模型中的保护作用;检测血清谷氨酸脱氢酶（GLDH）及肝组织中肝脏腺嘌呤核苷三磷酸（ATP）、二磷酸腺苷（ADP）、腺嘌呤核糖核苷酸（AMP）含量,评价药物对肝脏能量代谢及线粒体功能的调节作用;实时定量PCR及Western Blot法检测肝脏CYP1A2、CYP2E1 mRNA及蛋白水平,评价两药及其联合用药对肝脏CYP酶的调控作用。结果: 苦参碱（72.8 mg·kg^-1）、甘草甜素（43.4 mg·kg^-1）在CCl₄慢性肝损伤模型中均可降低大鼠血清ALT、AST（P<0.05）,两药联合（36.4 mg·kg^-1 苦参碱+21.7 mg·kg^-1 甘草甜素）使用保护作用更加显著(P<0.05);其中苦参碱（72.8 mg·kg^-1）、甘草甜素（43.4 mg·kg^-1）均可降低血清GLDH,并恢复肝脏ATP含量(P<0.05);苦参碱（72.8 mg·kg^-1）对CYP1A2、CYP2E1mRNA表达水平无抑制作用,甘草甜素（43.4 mg·kg^-1）对CYP1A2、CYP2E1mRNA及蛋白表达水平均有抑制作用（P<0.05）。结论: 苦参碱联合甘草甜素在慢性肝损伤模型中具有明显的线粒功能调节和肝保护作用。     

阿魏酸钠对甘油致小鼠肾脏氧化性损伤的拮抗效应阿魏酸钠对甘油致小鼠肾脏氧化性损伤的拮抗效应

目的从氧化应激角度,探讨阿魏酸钠对实验动物中毒性肾损害的防治作用。方法建立甘油所致小鼠急性肾小管损伤模型,观察不同剂量的阿魏酸钠对肾损伤小鼠肾功能指标、抗氧化指标和组织学的影响。结果在甘油注射后6和72 h,阿魏酸钠100～200 mg·kg^-1 ip能剂量依赖性的降低甘油所致血清尿素氮、肌酐和N-乙酰-β-葡糖苷酶的升高。阿魏酸钠200 mg·kg^-1减少肾组织丙二醛生成,提高肾脏谷胱甘肽含量及谷胱甘肽过氧化物酶、谷胱甘肽S-转移酶、过氧化氢酶和超氧化物歧化酶活性,且可明显减轻肾组织病理改变。结论阿魏酸钠对甘油致肾损伤有防治作用,其机制与增强肾脏抗氧化功能有关。     

脑5-HT1A/1B、α2受体及腺苷酸环化酶参与了胍丁胺的抗抑郁作用

为了在单胺受体及受体后腺苷酸环化酶(adenylate cyclase,AC)水平探讨胍丁胺(agmatine,AGM)抗抑郁作用的精细机制,采用小鼠悬尾实验和强迫游泳实验观察AGM抗抑郁行为改变。采用放射免疫方法测定大鼠前额皮层突触膜蛋白AC活性。结果表明,AGM(5～40 mg·kg^-1,ig)在小鼠悬尾实验和强迫游泳实验模型上均有显著抗抑郁活性。同时伍用β受体/5-HT_1A/1B受体阻断剂吲哚洛尔(pindolol, PIN, 20 mg·kg^-1, ip)、 α₂肾上腺素受体拮抗剂育亨宾(yohimbine, YOH, 5～10 mg·kg^-1, ip)或咪唑克生(idazoxan, IDA, 4 mg·kg^-1, ip)对AGM(40 mg·kg^-1, ig)的抗抑郁活性具有显著拮抗效应; 而β受体阻断剂普萘洛尔(propranolol, PRO, 5～20 mg·kg^-1, ip)或5-HT₃受体拮抗剂曲匹西隆(tropisetron, TRO, 5～40 mg·kg^-1, ip)对AGM(40 mg·kg^-1, ig)的抗抑郁活性无显著影响。AGM(0.1～6.4 μmol·L^-1)与大鼠前额皮层提取的突触膜共孵可剂量依赖地激活AC活性, 而PIN(1 μmol·L^-1)或YOH(0.25～1 μmol·L^-1)均显著拮抗AGM(6.4 μmol·L^-1)对AC的激活作用; 慢性给予大鼠AGM(10 mg·kg^-1, ig, bid)或氟西汀(fluoxetine, FLU, 10 mg·kg^-1, ig, bid) 2 w也显著增强大鼠前额皮层基础及Gpp(NH)p 预激活的AC活性。本研究表明, 调节脑内5-HT_1A/1B和α₂等受体功能, 并激活前额皮层AC可能是AGM抗抑郁活性的重要机制之一。     

芍药苷对佐剂性关节炎大鼠脾细胞产生抗体和cAMP水平的影响

探讨芍药苷(paeoniflorin,Pae)对佐剂性关节炎(adjuvant arthritis，AA)大鼠血清抗体水平和脾脏淋巴细胞cAMP水平的影响。大鼠足跖皮内注射弗氏完全佐剂(FCA)诱发大鼠AA模型，聚乙二醇(PEG)6000法检测血清循环免疫复合物(circulating immune complexes，CIC)；酶联免疫吸附(ELISA)法检测血清中抗C II抗体(anti-C II antibody)水平和抗结核杆菌抗体(anti-TB antibody)水平；放射免疫法(RIA)检测芍药苷体外给药对脾细胞中cAMP水平的影响。大鼠免疫后第17天开始分别灌胃给予芍药苷(25、 50及100 mg·kg^-1)和雷公藤多苷(40 mg·kg^-1)对照药，连续给药7 d。芍药苷(50及100 mg·kg^-1)可明显降低AA大鼠血清中升高的CIC水平、抗C II抗体水平和抗结核杆菌抗体水平，芍药苷组对AA模型组的抑制率(inhibition ratio，IR)与剂量呈正相关；芍药苷体外给药(12.5、62.5及312.5 mg·L^-1)使AA大鼠脾细胞升高的cAMP水平降低。芍药苷治疗后，明显降低AA大鼠的血清抗体水平及大鼠脾细胞升高的cAMP水平。     

重组小鼠β防御素3体内抗甲型流感病毒H1N1作用

目的 观察重组小鼠β防御素3(rMBD3)对甲型流感病毒感染小鼠的保护作用。方法 以10 mg·kg^-1·d^-1rMBD3腹腔注射3月,观察小鼠的一般状态,以及对主要脏器的影响。BALB/c小鼠,♀,分为正常对照组、模型对照组、rMBD3高剂量组(10 mg·kg^-1·d^-1)、rMBD3低剂量组(5 mg·kg^-1·d^-1)和利巴韦林组(100 mg·kg^-1·d^-1)。采用流感病毒液滴鼻感染建立甲型流感病毒H1N1感染小鼠模型,感染病毒12 h后分别腹腔注射给药。每日观察小鼠一般情况和死亡情况。于攻毒第3天检测肺泡灌洗液流感病毒滴度、血清γ干扰素含量、肺指数和肺组织病理变化。结果 小鼠腹腔注射10?mg·kg^-1·d^-1 rMBD3 3月,未发现明显异常反应或死亡,各重要脏器的未见明显病理改变。rMBD3各剂量组肺泡灌洗液中的病毒滴度、肺指数抑制率均降低,肺组织病理改变减少。结论 rMBD3对小鼠无明显毒性作用,在体内具有抗流感病毒、保护流感小鼠的活性。     

灵芝多糖肽对氧自由基损伤巨噬细胞的保护作用

目的:研究灵芝多糖肽(GLPP)在离体和整体水平对氧自由基(ROS)(tBOOH为氧化剂)损伤巨噬细胞的保护作用.方法:以tBOOH为氧化剂损伤小鼠腹腔巨噬细胞,以MTT法分析小鼠巨噬细胞存活率,在光镜和电子显微镜下观察细胞的形态改变.结果:GLPP50,100,200 mg/kg腹腔注射5天,能抑制巨噬细胞膜样变性和坏死,细胞存活率提高.在培养的巨噬细胞中加入 GLPP 3.125,12.5,50,200 mg/L,产生相似的保护作用.电镜观察发现,GLPP(100mg/kg)腹腔注射5天可保护细胞器如线粒体免受tBOOH的损伤.结论:GLPP有显著的清除氧自由基和抗氧化作用.     

灵芝多糖肽对人脐静脉内皮细胞氧化损伤的保护作用

目的研究灵芝多糖肽对人脐静脉内皮细胞(HU-VECs)氧化损伤的保护作用。方法原代培养人脐静脉内皮细胞,CD31免疫荧光法鉴定细胞。以叔丁基氢过氧化物(tBOOH)为氧化剂损伤细胞,造成氧化损伤模型,培养液中加入不同浓度灵芝多糖(6.125、12.5、25、50、100mg·mL-1),以CCK-8法检测细胞存活率;Hoechst333258检测细胞氧化损伤引起的凋亡;比色法检测Caspase-3活性变化;电镜检测细胞及细胞器形态学改变。结果灵芝多糖(6.125、12.5、25、50、100mg·mL-1)可减轻叔丁基氢过氧化物对HUVECs的氧化损伤,CCK-8检测灵芝多糖给药组,HUVEC细胞存活率增加。Hoechst33258检测给药组细胞凋亡数量较损伤组减少。比色法检测损伤组Caspase-3活性明显增高,给药组较损伤组减少。电镜可见灵芝多糖给药组减轻细胞器的氧化损伤,减少细胞凋亡。结论灵芝多糖肽(GLPP)对人脐静脉内皮细胞氧化损伤具有保护作用。     

Ganoderma Lucidum polysaccharide peptides protect kidney from renal ischemia reperfusion injury via counteracting oxidative stress

OBJECTIVE Ganoderma lucidum polysaccharide peptides(GLPP)have an anti-oxidant activity.The oxidative stress implicates in the pathogenesis of renal ischemia-reperfusion injury(RIRI).The objective of this study was to determine whether GLPP could attenuate RIRI via counteracting the oxidative stress.METHODS Mice subjected to uninephrectomy with the right kidney ischemia for 35 min and reperfusion for 24 hwere used to explore the protective activity of GLPP against RIRI.In GLPP-treated group,100mg·kg-1·d-1 of GLPP were intraperitoneally injected for 7dbefore the procedure.In vitro,NRK-52 Ecells subjected to hypoxia-reoxygenation(H/R)and tunicamycin were used to explore the protective effect of GLPP against oxidative stress.The mechanisms in which GLPP protected kidney from RIRI were studied using a series of physiological and molecular biological methods.RESULTS Kidneys undergone ischemia-reperfusion showed renal dysfunction and characteristic morphological changes including cellular necrosis,brush border loss,cast formation,vacuolization and tubular dilatation while these damages were significantly attenuated by GLPP treatment.The abnormal levels of MPO,MDA and SOD caused by renal ischemia-reperfusion were significantly reversed by GLPP treatment.More apoptotic cells were found in the renal ischemia-reperfusion group than the sham group whereas GLPP reduced apoptotic cells in the ischemia-reperfusion mice by21.75%(P<0.01).The GLPPs(25-1μg·mL)alleviated H/R induced cell viability loss by 20.12%(P<0.01)andΔφm dissipation by 27.3%(P<0.01)in vitro as well and its pretreatment dramatically reduced H/R and tunicamycin induced cell injury.CONCLUSION Our study found that GLPP had a protective effect on RIRI via its anti-oxidative capacity,which suggests that GLPP may be developed as a candidate drug for preventing acute kidney injury.     

Effects of chronic administration of S-adenosyl-l-methionine on brain oxidative stress in rats

S-adenosyl-L-methionine (SAM), used to treat liver diseases and as a coadjuvant in antidepressive medication, has neuroprotective effects in animal models. The aim of this study was to discover whether SAM has antioxidant effects in rat brain tissue. Ten male Wistar rats were killed by decapitation and the forebrains incubated with SAM for in vitro experiments. To study the effects of long-term administration, animals in four groups of ten rats each were given 10 mg SAM/kg per day s.c., and 40 other rats were given an equivalent volume of L-lysine (the commercial solvent for SAM). Treatment was started at the end of lactation, and animals were killed by decapitation after 15 days or 1, 6 or 22 months of treatment. The forebrain of each animal was used to test membrane lipid peroxidation by determining thiobarbituric acid-reactive substances (TBARS), glutathione level and enzyme activities related to glutathione (reduced form GSH, oxidized form GSSG) metabolism: GSH-peroxidase (GSHpx), GSSD-reductase (GSSGrd) and GSH-transferase (GSHtf). Chronic treatment with SAM decreased maximum forebrain production of TBARS by 46% compared with animals given L-lysine and increased glutathione levels by 50%, GSHpx activity by 115% and GSHtf activity by 81.4%. The results of in vitro experiments were qualitatively similar: lipid peroxidation was inhibited (13.1+/-1.3 nmol/mg protein in controls vs. 5.9+/-0.8 nmol/mg protein in samples incubated with 1000 micromol/l SAM) and glutathione levels were stimulated (0.97+/-0.06 micromol/g tissue in control samples vs. 1.55+/-0.08 micromol/g tissue in samples incubated with 1000 micromol/l SAM), as were GSHpx and GSHtf. No significant effect was seen in any of the experiments with L-lysine. We conclude that SAM has antioxidant effects in rat brain tissue both in vitro and ex vivo. The effect is seen both as inhibition of lipid peroxide production and as an enhancement of the endogenous glutathione antioxidant system.     

Antitumor and anti-angiogenic activity of Ganoderma lucidum polysaccharides peptide

AIM: To investigate the antitumor and anti-angiogenic activity of Ganoderma lucidum polysaccharides peptide (GLPP). METHODS: Antitumor effect of GLPP was observed in tumor-bearing mice in vivo. At the same time,the effects of GLPP on proliferation of tumor cells and human umbilical cord vascular endothelial cell (HUVEC) were detected by MTr assay in vitro. Subsequently, spleen lymphocytes proliferation of nude mice was stimulated by LPS or ConA. To investigate the anti-angiogenic effect of GLPP, GLPP 80 μg per disc and GLPP-treated serum 10μL per disc were added to the chick chorioallantoic membrane (CAM) respectively in vivo. RESULTS: GLPP 50, 100, and 200 mg/kg inhibited growth of Sarcoma 180 in BALB/c mice markedly by 35.2 %, 45.2 %, and 61.9 %,respectively. GLPP which was directly added to the cultured medium did not inhibit PG cell proliferation in vitro;but GLPP-treated serum 50, 100, 200 mg/kg potently inhibited PG cell proliferation by 22.5 %, 26.8 %, and 30.3 %,respectively; and reduced the xenograft (human lung carcinoma cell PG) in BALB/c nude mice greatly in vivo by 55.5 %, 46.0 %, and 46.8 %, respectively. Lymphocytes proliferation of nude mice could be stimulated by LPS 5 mg/L but not by ConA 2.5 mg/L, indicating that GLPP could not promote the T lymphocyte proliferation and neutral red phagocytosis of peritoneal macrophages of nude mice. The CAM assay showed that GLPP and GLPP-treated serum had anti-angiogenic effect. GLPP (1, 10, and 100 mg/L) inhibited HUVEC proliferation in vitro with the inhibitory rate of 9.4 %, 15.6 %, and 40.4 %, respectively. CONCLUSION: GLPP has antitumor and antiangiogenic activity. The anti-angiogenesis of GLPP may be a new mechanism underlying its anti-tumor effects.     

灵芝多糖肽对ECV304细胞氧化损伤的保护作用

目的研究灵芝多糖肽对ECV304氧化损伤的保护作用。方法培养ECV304细胞,以叔丁基氢过氧化物(tBOOH)为氧化剂损伤细胞,造成氧化损伤模型,培养液中加入不同浓度灵芝多糖(12.5、25、50、100mg.L-1),以MTT法测细胞存活率;以光镜、电镜检测细胞形态学改变及线粒体损伤;用AnnexinV/PI双标记细胞,流式细胞检测细胞凋亡的百分率。结果灵芝多糖(12.5、25、50、100mg.L-1)可减少叔丁基氢过氧化物对ECV304的氧化损伤,MTT检测灵芝多糖给药组,ECV304细胞存活率增加。光镜下可见细胞损伤减少,电镜可见灵芝多糖(50mg.L-1,温育24h)减轻细胞器如线粒体氧化损伤,减少细胞凋亡。细胞流式检测表明:对照组、给药组、损伤组总凋亡百分率分别2.24%±0.43%、24%±6.4%(P<0.01)、82.1%±7.9%。结论灵芝多糖肽(GLPP)对ECV304细胞氧化损伤具有保护作用。     

Temporal changes in oxidative stress and antioxidant activities in Ulva pertusa Kjellman

Temporal changes in the oxidative stress and antioxidant system in Ulva pertusa Kjellman collected in July, September, and November was evaluated. The lipid peroxidation was decreased in September and re-increased in November. Glutathione, the major thiol antioxidant molecule, was mostly in reduced form in September, but the glutathione was more oxidized and the content was significantly decreased in November. Glutamylcysteine ligase (GCL), the rate limiting enzyme for glutathione synthesis, activity was increased in September and November. Among the enzymes for glutathione recycling, the glutathione peroxidase (GPx) activity was highest in September, while the glutathione reductase (GRd) activity was highest in November. The superoxide dismutase (SOD) activity was significantly increased after September. The results suggest that reduced oxidative stress in September was due to the increased ROS scavenging capacity. The elevated oxidative stress in November indicates that the ROS generation should be exceedingly high despite the adaptively increased GCL, GRd, and SOD activities in cold season. Catalase activity was decreased after September, which might be relevant to the control of hydrogen peroxide concentration as a signaling molecule to modulate intrinsic seasonal changes in the algal metabolism rather than to the antioxidant function.     

Hepatic changes in adenine nucleotide levels and adenosine 3'-monophosphate forming enzyme in streptozotocin-induced diabetic mice

To elucidate the pathophysiological significance of adenosine 3'-monophosphate (3'-AMP) forming enzyme in mice, the effect of streptozotocin (STZ) on the enzyme activities and adenine nucleotide levels in the ICR mice (4-week-old) liver was examined. After 2 weeks, treatment with a single dosage of STZ (100, 150 or 200 mg/kg i.p.) induced a dose-dependent hyperglycemia and hypoinsulinemia but had no effect on serum alanine aminotransferase activity, indicating that STZ generated type 1 diabetes without hepatitis. In the diabetic liver, the activities of superoxide dismutase (SOD), catalase and ATP levels decreased, and the microsomal CYP2E1 activity increased. Changes of these biological activities might disrupt the cellular homeostatic balance of reactive oxygen species (ROS) production. The activities of 3'-AMP forming enzyme, one of the ribonucleases, in hepatic homogenates were not altered. However, in the STZ 200 mg/kg group, the cytosolic forming enzyme activities were enhanced, and inversely, the mitochondrial activity was reduced significantly, indicating that the decrease in the mitochondrial activity may be accelerated by development of diabetes due to the decrease in the antioxidant defense system and/or increase in ROS production. With the decrease in the 3'-AMP forming enzyme activity, the levels of 3'-AMP, a P-site inhibitor of adenylate cyclase, in mitochondrial were significantly reduced. These results obtained suggested that change in the mitochondrial 3'-AMP forming enzyme activity might reflect the pathophysiological change of mitochondrial function with the development of diabetes. Our results also suggested that change in cytosolic enzyme activity might serve as a new biomarker of oxidative stress because significant negative correlation between the activities of cytosolic 3'-AMP forming enzyme and SOD was found in the early stage of diabetes.     

Potential in vitro Protective Effect of Quercetin,Catechin, Caffeic Acid and Phytic Acid against Ethanol-Induced Oxidative Stress in SK-Hep-1 Cells

Phytochemicals have been known to exhibit potent antioxidant activity. This study examined cytoprotective effects of phytochemicals including quercetin, catechin, caffeic acid, and phytic acid against oxidative damage in SK-Hep-1 cells induced by the oxidative and non-oxidative metabolism of ethanol. Exposure of the cells to excess ethanol resulted in a significant increase in cytotoxicity, reactive oxygen species (ROS) production, lipid hydroperoxide (LPO), and antioxidant enzyme activity. Excess ethanol also caused a reduction in mitochondrial membrane potential (MMP) and the quantity of reduced glutathione (GSH). Co-treatment of cells with ethanol and quercetin, catechin, caffeic acid and phytic acid significantly inhibited oxidative ethanol metabolism-induced cytotoxicity by blocking ROS production. When the cells were treated with ethanol after pretreatment of 4-methylpyrazole (4-MP), increased cytotoxicity, ROS production, antioxidant enzyme activity, and loss of MMP were observed. The addition of quercetin, catechin, caffeic acid and phytic acid to these cells showed suppression of non-oxidative ethanol metabolism-induced cytotoxicity, similar to oxidative ethanol metabolism. These results suggest that quercetin, catechin, caffeic acid and phytic acid have protective effects against ethanol metabolism-induced oxidative insult in SK-Hep-1 cells by blocking ROS production and elevating antioxidant potentials.     

Pyrazole induced oxidative liver injury independent of CYP2E1/2A5 induction due to Nrf2 deficiency

Pyrazole can induce CYP2E1 and 2A5, which produce reactive oxygen species (ROS). Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates important antioxidant enzymes to remove ROS. In this study, we applied Nrf2 knockout mice to test the hypothesis that pyrazole will cause hepatotoxicity and elevate oxidative stress to a greater extent in Nrf2 knockout mice compared to wild type mice. Pyrazole induced severe oxidative liver damage in Nrf2 knockout mice but not in wild type mice. Activities and levels of CYP2E1 and 2A5 were elevated by pyrazole in the wild type mice but not in the Nrf2 knockout mice. However, expression or activity of Nrf2-regulated antioxidant enzymes, such as gamma-glutamylcysteine synthetase (GCS), heme oxygenase-1 (HO-1) and glutathione-S-transferase (GST), were upregulated in the pyrazole-treated wild type mice, but to a lesser extent or not at all in the pyrazole-treated Nrf2 knockout mice. Treatment with antioxidants such as vitamin C or S-adenosyl-l-methionine (SAM) or an inhibitor of iNOS prevented the pyrazole-induced oxidative liver damage, thus validating the role of oxidative/nitrosative stress in the pyrazole induced liver injury to the Nrf2 knockout mice. In summary, even though ROS-producing CYP2E1/2A5 were not elevated by pyrazole, impaired antioxidant capacity resulting from Nrf2 deficiency appear to be sufficient to promote pyrazole-induced oxidative liver injury.