不同产地当归中砷暴露对小鼠肝肾毒性损伤的研究

目的研究不同产地当归中重金属砷暴露对小鼠肝肾的损伤情况,并探讨其毒性.方法35只昆明种成年小鼠随机分为正常对照组、当归组(产地分别为云南、四川和陕西)和雄黄组共5组.小鼠灌胃给药72h 后处死,取血,肝脏和肾脏组织,全自动生化分析仪检测血清丙氨酸转氨酶(ALT)、天门冬氨酸转氨酶(AST)、尿素氮(UREA)和肌酐(CREA)含量,观察肝肾组织病理学变化;原子荧光光谱测定肝肾组织中的砷蓄积量;实时荧光定量(RT-PCR)检测砷毒性敏感基因金属硫蛋白-1(Metallothionein,MT-1)mRNA 和肿瘤坏死因子-α(TNF-α)mRNA 的表达水平.结果与对照组相比,雄黄组血清 ALT、AST、CREA 浓度水平和肝肾组织中砷蓄积量显著升高(P<0.05),并可能伴随肝肾功能的损伤, MT-1 mRNA 和 TNF-αmRNA 表达量升高但无统计学意义.当归组只在肝组织中检测到微量砷,肝肾功能病理学检查与正常对照组相似,MT-1 mRNA 和 TNF-αmRNA 表达量无显著升高(P>0.05).结论不同产地当归所含砷的毒性远小于雄黄毒性,高剂量雄黄给药对小鼠肝肾组织可能产生影响,但它们在一定剂量下被用于中药仍然是相对安全的.     

亚急性丙烯腈染毒对小鼠脑组织中Zn、Fe、Cu、Se含量的影响

丙烯腈(acrylonitrie,AN)是生产腈纶、塑料和树脂等化工产品的重要原料,也是国际组织确定的优先环境污染物。近年来人们对其神经毒性给予了较多关注,对其神经损害的行为效应和生化基础进行了大量探讨[1],也相继证实其神经损害的主要机制为直接影响胆碱能神经元、释放呼吸链抑制     

吗啡依赖大鼠脑组织内吗啡的免疫组织化学研究

目的··：研究吗啡依赖后大鼠脑内吗啡含量变化。方法··：对慢性染吗啡大鼠脑组织内的吗啡进行了原位免疫组织化学研究。结果··：染毒７ｄ大鼠脑组织内未能检出吗啡,染毒１４ｄ大鼠脑组织内出现了强弱不一的免疫反应。结·论·：大鼠对吗啡依赖形成过程中,脑组织内吗啡含量增高,且吗啡的分布与μ阿片受体分布一致。     

长期接触低剂量甲基汞大鼠脑组织病理观察

长期接触低剂量甲基汞大鼠脑组织病理观察李志超李永安毕晓颖（白求恩医科大学预防医学院，长春１３００２１）目前，环境汞污染的防治问题尚未解决，甲基汞可透过胎盘和血脑屏障，使其对人类健康更具有危害性．现今的研究还不能确定环境甲基汞对机体产生危害的界限浓度，...     

低剂量纳米银暴露致小鼠巨噬细胞RAW264.7的应激反应

目的：探讨纳米银(AgNPs)对小鼠巨噬细胞RAW264.7毒性效应的影响,为AgNPs生物安全性的研究提供依据。方法将不同浓度的AgNPs(0、6.25、12.5、25、50、60、80μg/ml)和RAW264.7共同培养,8、24 h后采用甲基噻唑基四唑比色法(MTT)测定各组细胞的活力,选取2.5、5μg/ml两个无明显细胞毒性的浓度进行后续研究,检测应激相关基因和蛋白表达的变化;采用酶联免疫吸附试验(ELISA)检测细胞培养液中炎症因子TNF-α和IL-6的表达。结果用2.5、5μg/ml的AgNPs处理细胞,24 h后相差显微镜下可见AgNPs进入细胞内,且5μg/ml组的细胞形态有明显改变;8、24 h后ELISA结果显示,IL-6无明显变化,在5μg/ml的24 h处理组TNF-α表达有显著升高,内质网应激相关的基因和蛋白在5μg/ml的24 h处理组表达明显上调。结论 RAW264.7细胞暴露于低剂量的AgNPs后表现出明显的应激反应,并且与暴露剂量和作用时间呈正相关。低剂量AgNPs能够干扰细胞的正常生理功能,长期暴露可能产生不可逆的损伤,应引起高度关注。     

砷对小鼠骨髓细胞DNA的损伤作用

了解砷对体内细胞ＤＮＡ的损伤作用及其机制。「方法」在小鼠饮水加入Ａｓ２Ｏ３喂养６个月,采用单细胞凝胶电泳技术对骨髓细胞ＤＮＡ断裂进行了分析。「结果高剂量组（１２．５ｍｇ／Ｌ）小鼠骨髓细胞ＤＮＡ的迁移度和迁移率显著高于阴性对照组,Ｐ〈０．０５;中、低剂量组小鼠骨髓细胞ＤＮＡ的迁移度和迁移率与性对照组无显著差异。     

砷对小鼠子代神经行为发育的影响

砷污染环境对人体健康的影响已引起人们高度重视,许多学者对此进行了大量研究。但关于砷的行为畸胎学方面的研究报道甚少。本研究采用一组神经行为功能测试方法,观察了孕鼠染砷对仔鼠神经行为发育的影响,以便为全面评价砷的发育毒性提供依据。     

孕期/哺乳期砷暴露对子鼠脑发育的影响

目的观察孕期/哺乳期环境水平砷暴露对子鼠中枢神经系统发育的影响。方法对昆明种小鼠全孕期和哺乳期以自由饮水方式连续染毒,饮水砷浓度分别为1、4和16 mg/L,对出生3和21 d的子鼠以ICP-MS法测定脑砷含量,HE染色观察脑形态发育。结果子鼠脑砷含量随母鼠饮水砷浓度升高而升高,呈剂量-反应关系(P!0.05)。光学显微镜下脑形态发育:与对照组比较,染砷子鼠大小脑皮层变薄,大脑单位面积神经元数目减少;染砷子鼠海马出现锥体细胞水肿、核浓缩,锥体细胞层变薄、锥体细胞层数减少,神经毡空隙增大等改变。结论孕期/哺乳期砷暴露可致子鼠脑形态发育异常;后者可能是砷神经发育毒性的解剖学基础。     

胚胎期砷暴露对成年小鼠海马神经炎症反应的影响

目的研究胚胎期砷暴露对成年小鼠海马组织神经炎症反应相关基因表达的影响,探讨砷影响认知发育的毒理学机制。方法 7周龄雌性和雄性ICR小鼠以2∶1的比例合笼交配,受孕小鼠随机分为4组,对照组饮用去离子水,低、中、高砷暴露组分别饮用含0.15 mg/L,1.5 mg/L,15 mg/L三氧化二砷的去离子水,攻毒处理至仔鼠出生,试验组母鼠停止砷暴露。各组分别选12只雌性仔鼠,于65日龄麻醉处死并分离海马组织,Trizol法提取总RNA,采用实时荧光定量-聚合酶链反应(qRT-PCR)技术检测相关基因的表达。结果与对照组相比,低浓度砷暴露组小鼠海马组织同种异体移植炎性因子-1(Aif-1)的表达显著升高(P<0.01);胶质纤维酸性蛋白(GFAP)的表达在低、中、高浓度砷暴露组均升高;CC趋化因子配体3(CCL3)的表达在中浓度砷暴露组中显著升高(P<0.05);N-甲基-D-天冬氨酸受体(NMDAR)亚基NR1的表达在中浓度砷暴露组中显著降低(P<0.05);NR2B的表达在中浓度砷暴露组中显著降低(P<0.01)。结论胚胎期砷暴露会引起小鼠成年期海马组织胶质细胞活化继而释放大量促炎症因子,并降低NMDAR有关亚基的表达,这是砷影响小鼠认知发育的分子机制之一。     

砷的雄性生殖毒性研究进展

砷是一种天然类金属化学元素,广泛存在于自然界中[1].同时,砷也是一种雄性生殖毒物,可影响下丘脑—垂体—睾丸轴、损害支持细胞和生精细胞,引起精子质量下降[2].本文就长期砷暴露所引起的雄性生殖毒性及相关机制进行综述. 1砷的雄性生殖毒性 1.1砷对下丘脑—垂体—睾丸轴的影响下丘脑—垂体—睾丸轴是男性生殖的重要调节路径,...     

Polymorphic trial in oxidative damage of arsenic exposed Vietnamese

Arsenic causes DNA damage and changes the cellular capacity for DNA repair. Genes in the base excision repair (BER) pathway influence the generation and repair of oxidative lesions. Single nucleotide polymorphisms (SNPs) in human 8-oxoguanine DNA glycosylase (hOGG1) Ser326Cys; apurinic/apyrimidinic endonuclease (APE1) Asp148Glu; X-ray and repair and cross-complementing group 1 (XRCC1) Arg280His and Arg399Gln in the BER genes were analyzed, and the relationship between these 4 SNPs and the urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) concentrations of 100 Vietnamese population exposed to arsenic was investigated. Individuals with hOGG1 326Cys/Cys showed significantly higher urinary 8-OHdG concentrations than did those with 326 Ser/Cys and Ser/Ser. As for APE1 Asp148Glu, heterozygous subjects showed significantly higher urinary 8-OHdG concentrations than did those homozygous for Asp/Asp. Moreover, global ethnic comparison of the allelic frequencies of the 4SNPs was performed in 10 population and previous reported data. The mutant allele frequencies of hOGG1 Ser326Cys in the Asian populations were higher than those in the African and Caucasian populations. As for APE1 Asp148Glu, Caucasians showed higher mutant frequencies than those shown by African and Asian populations. Among Asian populations, the Bangladeshi population showed relatively higher mutant allele frequencies of the APE1 Asp148Glu polymorphism. This study is the first to demonstrate the existence of genetic heterogeneity in a worldwide distribution of SNPs (hOGG1 Ser326Cys, APE1 Asp148Glu, XRCC1 Arg280His, and XRCC1 Arg399Gln) in the BER genes.     

DNA damage induced in brain cells of CBA mice exposed to magnetic fields

DNA migration, using single cell gel electrophoresis (comet assay), was studied on brain cells of CBA mice exposed continuously to 50 Hz, 0.5 mT magnetic fields (MF) for 2 hrs, 5 days or 14 days. No differences were observed in the groups MF-exposed for 2 hrs and 5 days compared with controls. However, in the group exposed to MF for 14 days, a significantly extended cell DNA migration was observed (0.02 < p < 0.05). These changes together with results from previous studies indicate that magnetic fields may have genotoxic effects in brain cells.     

Protein oxidative damage in arsenic induced rat brain: influence of DL-alpha-lipoic acid

A body of evidence has accumulated implicating free radical generation and reaction of arsenic with protein thiols in the biochemical and molecular mechanisms of arsenic toxicity. Brain readily undergoes oxidative damage, so it is important to determine whether arsenic-induced changes in rat brain may be associated with oxidative events. An increase in oxidative stress may contribute to the development of protein damage in rat brain. Present experiments were performed to study the effect of arsenic (sodium arsenite, 100 ppm mixed in drinking water) on protein oxidation and further to demonstrate the potential of dl-alpha-lipoic acid (70 mg/kg body weight) against arsenic-induced changes in different anatomic regions (cortex, striatum, cerebellum, hypothalamus and hippocampus) of the brain of male Wistar rats. We report here that arsenic treated rats had a significantly higher level of oxidised protein as assessed by increased carbonyl residues and decreased protein thiols (protein sulfhydryls) as compared to control rats in all five regions studied, with the most notable changes occurring in the cortex, striatum and hippocampus. Coadministration of lipoic acid along with arsenic resulted in reversal of the arsenic induced trends in carbonyl and sulfhydryl concentrations. The results of the study showed, lipoic acid treatment reduces oxidative protein damage in arsenic intoxicated rat brain regions, which is associated with its antioxidant activity that combines free radical scavenging and metal chelating properties.     

Mechanisms underlying arsenic carcinogenesis: hypersensitivity of mice exposed to inorganic arsenic during gestation

Inorganic arsenic is an important human carcinogen of unknown etiology. Defining carcinogenic mechanisms is critical to assessing the human health hazard of arsenic exposure but requires appropriate model systems. It has proven difficult to induced tumors in animals with inorganic arsenic alone. Several groups have studied the carcinogenic potential of inorganic arsenic in rodents, finding it to act as co-promoter or co-carcinogen, but not as a complete carcinogen. As gestation is a time of high sensitivity to chemical carcinogenesis, we performed two in utero exposure studies with inorganic arsenic. In the first study, pregnant mice received drinking water containing sodium arsenite at 0 (control), 42.5 and 85 ppm arsenic from gestation day 8 to 18, and the offspring were observed for up to 90 weeks. As adults, male offspring developed hepatocellular carcinoma (HCC) and adrenal tumors after in utero arsenite exposure. Although liver tumors were not induced by arsenic in female offspring, they did develop lung carcinoma, ovarian tumors, and uterine and oviduct preneoplasia. In a second study, the same doses of arsenic were used and the skin tumor promoting phorbol ester, TPA, was applied to the skin after birth in an effort to promote skin tumors potentially initiated by arsenic in utero. TPA did not promote dermal tumors after in utero arsenite exposure. Otherwise, results from the second chronic study largely duplicated the first and, irrespective of additional TPA exposure, arsenic exposure in utero induced HCC and adrenal tumors in males and ovarian tumors in females. In addition, combined arsenic and TPA induced a significant increase in hepatocellular tumors in female offspring, although arsenic alone was not effective. Thus, in utero inorganic arsenic exposure can act as a complete carcinogen in mice, with brief exposures consistently inducing tumors at several sites. In addition, it appears gestational arsenic can act as a tumor initiator in the female mouse liver, inducing liver lesions that can be promoted by TPA.     

Aberrant DNA methylation and gene expression in livers of newborn mice transplacentally exposed to a hepatocarcinogenic dose of inorganic arsenic

Our prior work showed that brief exposure of pregnant C3H mice to inorganic arsenic-induced hepatocellular carcinoma (HCC) formation in adult male offspring. The current study examined the early hepatic events associated with this oncogenic transformation. Pregnant mice were exposed to a known carcinogenic dose of arsenic (85 ppm) in the drinking water from gestation days 8 to 18. The dams were allowed to give birth and liver samples from newborn males were analyzed for arsenic content, global DNA methylation and aberrant expression of genes relevant to the carcinogenic process. Arsenic content in newborn liver reached 57 ng/g wet weight, indicating arsenic had crossed the placenta, reached the fetal liver and that significant amounts remained after birth. Global methylation status of hepatic DNA was not altered by arsenic in the newborn. However, a significant reduction in methylation occurred globally in GC-rich regions. Microarray and real-time RT-PCR analysis showed that arsenic exposure enhanced expression of genes encoding for glutathione production and caused aberrant expression of genes related to insulin growth factor signaling pathways and cytochrome P450 enzymes. Other expression alterations observed in the arsenic-treated male mouse newborn liver included the overexpression of cdk-inhibitors and stress response genes including increased expression of metallothionein-1 and decreased expression of betaine-homocysteine methyltransferase and thioether S-methyltransferase. Thus, transplacental exposure to arsenic at a hepatocarcinogenic dose induces alterations in DNA methylation and a complex set of aberrant gene expressions in the newborn liver, a target of arsenic carcinogenesis.     

Formation of 8-oxodeoxyguanosine in brain DNA of rats exposed to acrylonitrile

Acrylonitrile (ACN) produces tumors in rats, particularly gliomas of the brain, but tests for genotoxicity have yielded mixed results and no ACN-DNA adducts have been identified in the brain. To examine the possibility that ACN-related brain tumors were not a consequence of binding of ACN to brain DNA, experiments were conducted to investigate possible epigenetic mechanisms. Male Sprague-Dawley rats were exposed to 0, 3, 30, and 300 ppm ACN in drinking water for 21 days, a range that includes doses associated with brain tumorigenesis. In the 30 and 300 ppm ACN groups, 8-oxodeoxyguanosine (8-oxodG) levels were two fold greater than in the controls. Measures of glutathione levels, glutathione peroxidase and catalase were not significantly changed, but cyst(e)ine was somewhat increased. No changes were found in brain cytochrome oxidase activity, which indicates a lack of metabolic hypoxia. Also, no effects on thiobarbituric acid reactive substances were found, indicating a lack of lipid peroxidation. In an additional experiment, male Sprague-Dawley rats were exposed to 0 or 100 ppm ACN in drinking water for 94 days; interim sacrifices were conducted at 3, 10, and 31 days. Levels of brain nuclear DNA 8-oxodG were significantly increased in ACN-exposed rats compared with controls. Another group of animals were given weekly i.v. injections of 5 mg/kg methylnitrosurea and no increases in 8-oxodG were found. These studies suggest the possibility that ACN-induced tumors may be produced by a mode of action involving 8-oxodG. The formation of 8-oxodG is not understood, but does not appear to involve lipid peroxidation or disruption of antioxidant defenses. Received: 15 December 1997 / Accepted: 10 February 1998     

Leucocytes DNA damage in mice exposed to JS-118 by the comet assay

JS-118 is an extensively used insecticide in China. The present study investigated the genotoxic effect of JS-118 on whole blood at 24, 48, 72 and 96 h by using alkaline comet assay. Male Kunming mice were given 6.25, 12.5, 25, 50 and 100 mg/kg BW of JS-118 intraperitoneally. A statistically significant increase in all comet parameters indicating DNA damage was observed at 24 h post-treatment (p < 0.05). A clear concentration-dependent increase of DNA damage was revealed as evident by the OTM (arbitrary units), tail length (μm) and tail DNA (%). From 48 h post-treatment, a gradual decrease in mean comet parameters was noted. By 96 h of post-treatment, the mean comet tail length reached control levels indicating repair of damaged DNA. This study on mice showed different DNA damage depending on the concentration of JS-118 and the period of treatment. The present study provided further information of the potential risk of the genetic damage caused by JS-118.     

Combination of low dose ethanol and caffeine protects brain from damage produced by focal ischemia in rats

Caffeine and ethanol are two commonly overused psychoactive dietary components. The purpose of this study was to assess the effects of acute, chronic, oral (p.o.) and intravenous (i.v.) caffeine, ethanol and their combination on infarct volume following focal ischemia in rats. Rats received treatment either p.o. 3 h and 1 h before, or by i.v. infusion for 2.5 h beginning 30-180 min after, ischemia. There were six acute treatment groups. (1) oral dH2O (control); (2) oral caffeine (10 mg/kg); (3) oral ethanol (0.65 g/kg total); (4) oral ethanol plus caffeine; (5) intravenous saline; and (6) intravenous ethanol (0.65 g/kg) plus caffeine (10 mg/kg) in saline. A 7th group received oral ethanol plus caffeine for three weeks prior to ischemia. After 3 h of left MCA/CCA occlusion and 24 h reperfusion, infarct volume was determined. Control animal infarct volume was 102.4+/-42.0 mm3. Oral caffeine alone had no effect (122.4+/-30.2 mm3). Oral ethanol alone exacerbated infarct volume (177.2+/-27.8 mm3). Oral caffeine plus ethanol almost entirely eliminated the damage (17.89+/-10.41 mm3). When i.v. treatment with ethanol plus caffeine was initiated at 30, 60, 90 and 120 minutes post-ischemia the infarct volume was reduced by 71.7%, 49.8%, 64.8% and 47.1%, respectively. Chronic daily oral ethanol plus caffeine prior to ischemia eliminated the neuroprotection seen with acute treatment. These studies indicate that ethanol, which by itself aggravates cerebral ischemia, and caffeine, when combined together immediately before or for 2 h after focal stroke, reduces ischemic damage.