Effect of Selenium Pretreatment in Chronic Mercury Intoxication in Rats

Effect of selenium pretreatment (0.2 mg/kg/day, as sodium selenite), 4 h prior to mercury treatment (0.4 mg/kg/day, as mercuric chloride), administered intraperitoneally, was examined after daily exposure for 20 days’ in rats. Liver, kidney and brain tissues were assayed for malondialdehyde (MDA) level, glutathione (GSH) content and mercury concentration. Mercury induced MDA levels, which was also observed in selenium pretreated animals. Significant reduction in GSH levels was observed in mercury alone and selenium pretreated animals. Mercury accumulation was in the order of kidney, liver and brain. Selenium pretreatment resulted in further enhancement in mercury accumulation in liver and kidney.     

Role of selenium in mercury intoxication in mice

Studies were conducted to examine the effect of pre and post-treatment of selenium in mercury intoxication (20 micromole/ kg b.w. each given intraperitoneally) in mice in terms of lipid peroxidation (LPO), glutathione (GSH) content, activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and mercury concentration in liver, kidney and brain. No significant alteration was observed in all the organs examined after mercury or selenium treatment in LPO and GSH but administration of selenium (pre and post) resulted in an increase in the level of LPO and GSH. The activity of SOD was depleted in liver and kidney while that of GPx was lowered in liver of mercury exposed animals. Selenium administration resulted in restoration of the depletion of these enzymatic activities. The activity of CAT in liver and brain was enhanced both in mercury and selenium treated animals. Administration of selenium significantly arrested enhanced CAT activity. Kidney showed the highest mercury concentration among the organs examined. Administration of selenium resulted in further enhancement of mercury concentration in the tissues. An increase in selenium level in liver was observed after mercury treatment, which was also restored by mercury selenium co-administration. Our results indicate that the prooxidant effect of selenium was greater by its pretreatment.     

褪黑素对低硒饮食大鼠脂质过氧化的影响

目的 :研究褪黑素对低硒粮喂养的大鼠脂质过氧化增强的影响 ,并讨论其可能机制。方法 :将SD大鼠分为 3组 ,分别用低硒饲料、低硒饲料加硒、低硒饲料加褪黑素灌胃饲养 ,12周时检测血Se、血GSH—Px及心肌组织、肝组织匀浆MDA水平。结果 :12周时低硒组大鼠血Se、GSH—Px较加硒组 (对照组 )显著降低 ,心肌组织、肝组织匀浆MDA均明显高于其它两组。加硒组与褪黑素组MDA无显著差异。结论 :褪黑素可以显著抑制低硒饮食大鼠脂质过氧化的增强 ,作用与其抗氧化机制有关     

Antioxidant responses and bioaccumulation in Ictalurus melas under mercury exposure

Laboratory experiment was carried out to determine mercury accumulation in tissues (gills, kidneys, liver, and muscle) and biochemical responses in the liver of freshwater teleost Ictalurus melas. Catfish were subjected to different concentrations of Hg(2+) (35, 70, and 140 microg/L) for 10 days. The chemical analyses showed higher mercury concentrations for all treatments in gills and kidneys followed by liver and muscle. At the lowest mercury concentration a decrease in glutathione (GSH) content and an increase of GSH peroxidase Se-dependent and glyoxalase II enzymes were observed. An increasing trend was observed also for GSH-S-transferase and glyoxalase I, while GSH peroxidase Se-independent enzyme and GSH reductase showed no significant variation in activities. The increase in the enzymes activities of catfish, involved in the inactivation of reactive molecules formed during oxidative stress, could provide an additional protection against the oxidative damage induced by mercury.     

Hepatic metabolism of glucose and linoleic acid varies in relation to susceptibility to fatty liver in ad libitum-fed Muscovy and Pekin ducks

The susceptibility to develop hepatic steatosis is known to differ between duck species, especially between Muscovy and Pekin ducks. This difference could be explained by either differential responses of species to overfeeding or genetic differences in hepatic lipid metabolism. The aim of the present study was to compare the intensities of the different hepatic pathways (oxidation, lipogenesis, esterification, secretion, etc.) of the two main nutrients (glucose and linoleic acid (LA)) reaching the liver of ad libitum-fed Muscovy (n 6) and Pekin (n 6) ducks using the ex vivo method of liver slices incubated for 16 h with [U-14C]glucose, [1-14C]LA and [35S]methionine added to the survival medium. In such experimental conditions, the lipogenesis pathway from glucose was 2-fold higher (P<0.05) in the liver of the Muscovy duck than in that of the Pekin duck. Furthermore, the hepatic uptake of LA was 2-fold higher (P<0.05) in the Muscovy duck than in the Pekin duck leading to a 2-fold higher (P<0.05) esterification of this fatty acid in the liver of the Muscovy duck. The hepatic secretion of VLDL was higher (P<0.01) in the Muscovy duck than in the Pekin duck but insufficient to prevent lipid accumulation in the liver of the Muscovy duck. In conclusion, these results show the influence of the species on the hepatic metabolism of ducks in relation to their susceptibility to develop fatty liver. These results should shed light on the metabolic regulations that might underlie susceptibility to hepatic steatosis in the the human liver.     

黑木耳硒多糖对小鼠血脂、血硒及过氧化物酶的影响

目的　探讨黑木耳硒多糖对血脂、血硒浓度及谷胱甘肽过氧化物酶活性的影响。方法昆明系雄性小白鼠随机分成四组 :正常对照组 ( )、高脂对照组 ( )、亚硒酸钠组 ( )、硒多糖组( )。 和 组饲喂高脂饲料。并每日每鼠分别灌胃亚硒酸钠或硒多糖水溶液 1 ml(1 .95μg Se/ml) ,共 2 1 d。结果　与 组比 , 、 组小鼠血清 TC显著降低 (P<0 .0 0 1 ) ,GSH- Px活性显著增强 (P<0 .0 0 1 ) ; 组小鼠血清 TG显著降低 (P<0 .0 5) ,血硒浓度显著提高 (P<0 .0 1 ) ; 组小鼠血清 TG显著降低 (P<0 .0 1 ) ,血硒浓度显著提高 (P<0 .0 0 1 ) ;与 组比 , 组硒血浓度显著提高(P<0 .0 0 1 ) ,GSH- Px活性显著增强 (P<0 .0 1 )。结论　硒多糖较亚硒酸钠具有更好的降血脂、提高血硒浓度和增强 GSH- Px活性的作用 ,对高血脂症有一定的预防作用     

Association of selenium status and blood glutathione concentrations in blacks and whites

Selenium deficiency has been linked with increased cancer risk and, in some studies, selenium supplementation was protective against certain cancers. Previous studies have suggested that selenium chemoprevention may involve reduced oxidative stress through enhanced glutathione (GSH). Our objectives were to examine the relationships between selenium and GSH in the blood and the modifying effects of race and sex in free-living adults and individuals supplemented with selenium. Plasma selenium concentrations and free and bound GSH concentrations and γ-glutamyl cysteine ligase (GCL) activity in the blood were measured in 336 healthy adults (161 Blacks, 175 Whites). Plasma selenium and blood GSH were also measured in 36 healthy men from our previously conducted placebo-controlled trial of selenium-enriched yeast (247 μg/day for 9 mo). In free-living adults, selenium concentrations were associated with increased blood GSH concentration and GCL activity (P < 0.05). Further, selenium was significantly higher in Whites than in Blacks (P < 0.01). After 9 mo of supplementation, plasma selenium increased 114% in Whites and 50% in Blacks (P < 0.05), and blood GSH increased 35% in Whites (P < 0.05) but was unchanged in Blacks. These results indicate a direct association between selenium and GSH in the blood of both free-living and selenium-supplemented individuals, with race being an important modifying factor.     

汞矿地区大米对大鼠生长发育及氧化损伤的影响

目的探讨汞矿地区大米暴露对大鼠生长发育的影响及氧化损伤机制。方法利用汞矿地区大米及对照组大米分别对SD大鼠进行90d暴露实验,观察大鼠的体重变化情况,90d后处死,测定大鼠脑、肝、肾组织谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活力及还原型谷胱甘肽(GSH)、丙二醛(MDA)含量。结果与对照组相比,实验组大鼠的体重增幅较大,脑、肝、肾组织中GSH-Px、SOD活力和GSH含量降低(P<0.05),MDA含量升高,差异均有统计学意义(P<0.01)。结论大鼠暴露于汞污染大米90d后脑、肝、肾均产生了明显的脂质过氧化。     

氟硒镉对大鼠体内抗氧化酶及微量元素的影响

目的　探讨氟硒镉对大鼠各组织中脂质过氧化物 (LPO)含量和谷胱甘肽过氧化物酶 (GSH Px)活性以及镉硒锌等微量元素含量的影响。方法　采用SD大鼠经饮水染毒 8周 ,实验结束时处死动物测定各组织中LPO和谷胱甘肽过氧化物酶及镉硒锌的含量。结果　氟、硒、镉实验组均可见大鼠血清、肝、肾组织中GSH Px含量与对照组比呈显著降低 ,LPO含量量呈显著增高。其中任意二元素联合组较氟、硒、镉组GSH Px的含量呈明显回升 ,LPO含量量呈明显降低 ,而氟 +硒 +镉组其升高与降低的作用则更明显 ,以至GSH Px、LPO的水平几乎和对照组相同。过量硒和镉能导致肾硒、肝镉成数倍的增长。氟、镉可引起各组织中硒、锌的缺乏 ,硒则可使肝、肾中锌水平普遍提高。氟 +硒、镉 +硒以及氟 +硒 +镉联合可减少肾硒、肝镉的蓄积 ,同时也可减少氟、镉所致锌的损失。结论　提示过量的氟、硒、镉均可促进动物体内脂质过氧化作用增强 ,并抑制GSH Px的活性 ,使机体抗氧化能力降低。但当其中二或三种化学元素共存时 ,可减轻各自所引起的脂质过氧化作用以及对GSH Px的活性的抑制作用 ,同时减轻镉硒在体内的蓄积和氟镉所致引起体内锌水平的降低。     

Optimization and application of glutamate cysteine ligase measurement in wildlife species

Glutamate cysteine ligase (GCL), synthesizing gamma-glutamylcysteine from glutamate and cysteine, is the rate-limiting enzyme in glutathione (GSH) biosynthesis. GCL activity measurement was optimized in tissues from deer mice, Sprague Dawley rats, and mallard ducks. Varying glutamic acid concentrations from 5 to 80 mM did not affect GCL activities markedly, whereas cysteine concentrations from 2.5 to 40 mM influenced GCL activities substantially. Optimal cysteine concentrations for deer mouse, Sprague Dawley rat, and mallard duck (respectively) were 30, 30, and 20 mM in liver, 10, 10, and 20 mM in kidney, 20, 20, and 30 mM in brain, and 30 mM in heart for all three species. Responses of mallard duck GCL activity to acid metalliferous water were evaluated. After subacute exposure, low doses increased GCL activity and GSH content in liver by 48.3% and 54.4%, respectively. High doses reduced GCL activities significantly in liver and kidney to 31.2% and 43.0% of the control, respectively.     

纳米硒对大鼠急性胃粘膜损伤的保护作用

目的研究不同剂量纳米硒对大鼠急性胃粘膜损伤是否有保护作用。方法将50只健康Wister大鼠随机分为5组:正常对照组、模型对照组、纳米硒低、中、高剂量组,含纳米硒剂量分别为4.17、8.33和16.67μg/kg,用无水乙醇诱导大鼠急性胃粘膜损伤(AGML),然后进行胃粘膜组织病理学检查,分别测定各组大鼠胃粘膜损伤指数(UI)、血清谷胱甘肽过氧化物酶(GSH-Px)活性、丙二醛(MDA)含量。结果与模型对照组比较,纳米硒各剂量组的损伤指数显著降低(P<0.01),且呈剂量依赖性,血清中GSH-Px活性显著升高(P<0.01),MDA含量下降(P<0.05,P<0.01),粘膜损伤程度明显减轻。结论纳米硒对无水乙醇诱导的急性胃黏膜损伤有明显的保护作用,其机制可能与抗氧化作用有关。     

松花江汞污染综合治理后儿童发汞含量的调查

目的　了解松花江主要汞污染源综合治理后 ,环境汞污染现状及儿童体内汞蓄积水平。方法　设对照组与观察组 ,分别采集地面水、土壤、粮食、鱼及儿童头发 ,测定汞含量 ,并分别与 1 982年 (治理前 )和 1 992年 (即治理1 0年后 )汞含量水平比较。结果　观察组水、土壤、鱼汞含量显著低于 1 982年及 1 992年 (P <0 0 1 ) ;与对照组比较差异无统计学意义 (P >0 0 5 ) ,均未超过相应的卫生标准。观察组粮食汞含量与 1 982年及 1 992年相比明显降低 (P <0 0 1 ) ,但明显高于对照组 (P <0 0 5 )。观察组儿童发汞明显低于 1 982年及 1 992年 ,与对照组比较差异无统计学意义 (P >0 0 5 )。结论　松花江汞污染综合治理后环境汞污染状况已明显改善 ,未发现儿童体内汞蓄积现象。     

硒酸酯多糖对化疗致癌症患者脂质过氧化的拮抗作用

为了解硒酸酯多糖对肿瘤患者体内过氧化脂质（ＬＰＯ）及谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）活性的影响，对６０例肿瘤病人随机分成三组：不服硒组、服硒４００μｇ／ｄ组及８００μｇ／ｄ组，并与１５名正常人对照比较。结果为癌患者血清ＬＰＯ明显高于正常人（Ｐ＜０．０１），血清Ｓｅ明显低于正常人（Ｐ＜０．０１），而全血ＧＳＨ含量及ＧＳＨ－Ｐｘ活性明显低于正常人（Ｐ＜０．０５）。服硒酸酯多糖者化疗后血清Ｓｅ较不服者明显升高（Ｐ＜０．０５），ＧＳＨ及ＧＳＨ－Ｐｘ活性明显升高（Ｐ＜０．０１，Ｐ＜０．０５），而ＬＰＯ含量显著下降（Ｐ＜０．０５）。服硒酸酯多糖４００μｇ／ｄ组与８００μｇ／ｄ组之间上述各指标均无明显差异。提示肿瘤病人摄入适量（４００μｇ／ｄ）硒酸酯多糖可增加体内ＧＳＨ－Ｐｘ活性，减轻化疗药物对正常细胞的过氧化损伤。     

Effect of selenium depletion and repletion on plasma glutathione and glutathione-dependent enzymes in the rat

Selenium deficiency has several known biochemical effects. In the rat, these effects include loss of glutathione peroxidase (GSH-Px) activity, increased plasma glutathione concentration and increased liver glutathione S-transferase (GSH S-Tr) activity. The time course of the development of these changes in rats fed selenium-deficient diets and the time course of reversal of these changes in selenium-deficient rats fed graded levels of selenium were determined. As selenium deficiency was produced, liver cytosolic and plasma GSH-Px activities decreased first and were less than 5% of control when plasma glutathione concentration and liver GSH S-Tr activity began to increase. Elevated liver GSH S-Tr activity in selenium-deficient rats was corrected by refeeding selenium at the lowest level of supplementation (0.015 ppm) for 4 wk. GSH-Px activity required a supplementation of 0.10 ppm selenium for correction to control levels in 4 wk. Based on these studies a classification of the severity of selenium deficiency into mild, moderate and severe categories is proposed. In addition, the effect of dietary sulfur amino acid supplementation on plasma glutathione concentration was studied.     

Mercury and selenium content and chemical form in fish muscle

Data on the content, chemical form, and distribution of mercury and selenium in edible muscle are presented for several species of marine and freshwater fish. For most species, 60 to 95% of the total mercury content is present as methylmercury. For all species, 15 to 35% of the total selenium content is in the form of selenate (Se VI). Muscle selenium content does not correlate with the corresponding mercury content. For freshwater and processed (canned) marine samples, 60 to 90% of the total mercury content is water-extractable. On a percentage basis, methylmercury is slightly more extractable than inorganic mercury. For nonprocessed marine samples, only 25 to 45% of the total mercury is water-extractable, inorganic mercury being more extractable than methylmercury. For all species, 55 to 80% of the total selenium content is water-extractable, Se VI is more extractable on a percentage basis than selenite (Se IV) and selenide (Se-II).     

Duck cerebellum participates in regulation of food intake via the neurotransmitters serotonin and neuropeptide Y

Two important neurotransmitters, serotonin (5-hydroxytryptamine, 5-HT) and neuropeptide Y (NPY), have been confirmed to be involved in food intake regulation. To clarify whether the cerebellum participates in modulation of food intake through these two neurotransmitters, we investigated the distribution and expression levels of 5-HT and NPY in cerebellum of the duck. Our results showed that 5-HT and NPY were distributed only at the Purkinje cell layer of the duck cerebellum. Moreover, the expression level of 5-HT in fasted (4 h) and tryptophan (100-200 mg/kg)-treated ducks was significantly higher than that in control animals (P<0.01), whereas the expression of NPY was significantly decreased (P<0.01). Therefore, our results indicated that inhibitory regulation of food intake respectively increased and decreased cerebellar 5-HT and NPY in the duck.     

谷胱甘肽和牛磺酸对汞急性肾毒性影响的实验研究

目的 探讨预先投予GSH和牛磺酸对汞急性肾毒性的影响。方法 将32只Wistar大鼠随机分为对照、HgCl2染毒、GSH HgCl2和牛磺酸 HgCl2 4组。对照组皮下注射0．9％的生理盐水,汞染毒组皮下注射2．5mg／kg的HgCl2溶液,注射容量为5ml／kg。GSH和牛磺酸组于注射相同剂量Hg口2前2h分别腹腔注射3mmoL/kg的GSH溶液和4mmol／kg的牛磺酸溶液。测定尿N-Z乙酰-β-D氨基葡萄糖苷酶(NAG)、碱性磷酸酶(ALP)、乳酸脱氢酶(LDH)活性,尿蛋白和尿肌酐含量,血清尿素氮(BUN)以及尿汞和肾汞含量。结果 与对照组比较,HgCl2染毒组尿NAG、ALP、LDH活性显著升高,尿蛋白、BUN、尿汞、肾汞含量明显增加。预先投予GSH和牛磺酸后,可使汞染毒大鼠尿NAG和ALP活性、尿蛋白和BUN含量均较HgCl2染毒组显著减低;GSH组尿汞显著低于单纯染汞组,而牛磺酸组尿汞、肾汞与汞染毒组比较差异则无显著性。结论 GSH和牛磺酸对汞致急性肾损伤有一定的保护作用。     

Toxicity and oxidative stress of different forms of organic selenium and dietary protein in mallard ducklings

Concentrations of over 100 ppm (mg/kg) selenium (Se) have been found in aquatic plants and insects associated with irrigation drainwater and toxicity to fish and wildlife. Composition of diet for wild ducklings can vary in selenium-contaminated environments. Earlier studies have compared toxicities and oxidative stress of Se as selenite to those of seleno-DL-methionine (DL) in mallards (Anas platyrhynchos). This study compares DL, seleno-L-methionine (L), selenized yeast (Y) and selenized wheat (W). Day-old mallard ducklings received an untreated diet (controls) containing 75% wheat (22% protein) or the same diet containing 15 or 30 ppm Se in the above forms except for 30 ppm Se as W. After 2 weeks, blood and liver samples were collected for biochemical assays and Se analysis. All forms of selenium caused significant increases in plasma and hepatic glutathione peroxidase activities. Se as L at 30 ppm in the diet was the most toxic form, resulting in high mortality (64%) and impaired growth (>50%) in survivors and the greatest increase in ratio of oxidized to reduced hepatic glutathione (GSH). Se as both L and DL decreased the concentrations of hepatic GSH and total thiols. Se as Y accumulated the least in liver (approximately 50% of other forms) and had less effect on GSH and total thiols. In a second experiment, in which the basal diet was a commercial duck feed (22% protein), survival was not affected by 30 ppm Se as DL, L, or Y and oxidative effects on GSH metabolism were less pronounced than with the wheat diet.     

氟中毒氧化应激与细胞凋亡关系的研究

目的 研究氟、硒对大鼠肝细胞氧化应激和细胞凋亡的影响.方法 大鼠经饮水加氟化钠(150mg/L)或/和亚硒酸钠(2mg/L)10周后,检测肝细胞凋亡百分率、细胞周期构成比、活性氧(ROS)和还原型谷胱甘肽(GSH)含量以及脂质过氧化物(LPO)水平.结果 氟可使肝细胞凋亡百分率明显升高,S期细胞数增多,ROS和LPO水平升高,GSH含量下降;硒通过稳定细胞GSH含量可拮抗氟的毒性作用,使组织中ROS、LPO水平下降,GSH含量升高,凋亡百分率下降.结论 硒可部分拮抗氟化物诱导的肝细胞脂质过氧化和凋亡,氧化应激参与了介导细胞凋亡的过程.     

甲醛吸入对小鼠不同组织器官谷胱苷肽水平的影响

目的　探讨经不同浓度甲醛吸入对小鼠不同组织器官的氧化损伤作用及其分子机理。方法　用 1m g/ m3和 3m g/ m3的甲醛气体对小鼠进行染毒处理 ,测定吸入甲醛后 5种器官 (脑、心、肝、肺、肾 )的谷胱苷肽 (GSH)含量。结果　吸入 1mg/ m3甲醛的小鼠 ,心、肺、肝、肾的 GSH含量明显下降 (P<0 .0 1,P<0 .0 5 ) ,其中心最为严重 ;吸入 3mg/ m3甲醛的小鼠 ,所试全部器官的 GSH水平均显著下降 (P<0 .0 0 1,P<0 .0 1,P<0 .0 5 ) ,脑、心、肾最为严重 ,肺次之 ,肝较轻。结论　气态甲醛对机体的各组织器官均有氧化损伤作用 ,是一种全身性毒物。