对氧磷酶在有机磷农药中毒中的研究进展

对氧磷酶(Paraoxonase,PON)是一类广谱的非专一性酯酶.对氧磷酶家族至少有3个成员,PON1、PON2和PON3.PON在有机磷酸代谢中具有重要作用,被认为是可开发治疗有机磷中毒的有前途的方法.本文综述了PON的性质、基因多态性、催化活性及PON在有机磷农药中毒中的重要作用.     

对氧磷酶的基因多态性对有机磷作业工人血清对氧磷酶活力的影响

目的探讨对氧磷酶(PON1)的基因多态性对接触有机磷的作业工人血清对氧磷酶(sPON)活力的影响。方法采用标准曲线法测定作业工人和对照者sPON活力,PCR-限制性片段长度多态性分析PON1基因192位点的基因型。结果合并敌敌畏和对硫磷暴露组后,不同基因型sPON活力均值为195.0(谷氨酸纯合子,Gln/Gln)、304.6(谷氨酸/精氨酸杂合子,Gln/Arg)和368.4(精氨酸纯合子,Arg/Arg),呈Gln/Gln→Gln/Arg→Arg/Arg递增的趋势,并且差异有统计学意义(P=0.03)。结论PON1基因192位点的多态性影响sPON的活力,可能调节个体对甲基对硫磷的毒性的易感性。     

对氧磷酶的某些研究进展

对氧磷酶 (PON)多基因家族至少有 3个成员 ,包括PON1、PON2和PON3。PON1是PON多基因家族中发现最早 ,研究最多的成员 ,其基因产物血清对氧磷酶在有机磷神经毒剂解毒中起重要作用 ,其基因多态性与脑卒中、动脉粥样硬化、冠心病及 2型糖尿病发病等有密切关系 ;PON2基因多态性与家族性高胆固醇血症、糖尿病等有关 ;PON3基因产物目前尚未有在人体组织中存在的报道 ,它们的生理作用仍在探索中。现将PON研究的进展综述如下。1　PON多基因家族PON多基因家族至少存在 3个成员 :PON1、PON2、PON3,它们位于人类 7号染色体的长臂q2 1 …     

热应激有机磷毒物中毒对小鼠全血乙酰胆碱酯酶活力的影响

目的 高温环境超过机体调节适应的生理限度时,机体发生失代偿性反应。有机磷毒物抑制胆碱酯酶(ChE)活性,造成体内乙酰胆碱(ACh)的堆积而中毒。本实验试阐述热应激和有机磷毒物中毒两种因素同时作用于小鼠,对小鼠的体重变化及全血的乙酰胆碱酯酶(AChE)活力的影响。方法 将54只小鼠随机分为对照组、热应激组和热应激有机磷毒物中毒组。热应激组小鼠放在相对湿度（60±5）%,温度分别为（38℃±1℃）和（40℃±1℃）的热环境下1 h,密切观察小鼠一般情况,热应激前后小鼠称重记录。有机磷毒物中毒组小鼠ip给予有机磷毒物9和15 mg·kg^-1;染毒30 min后,处死小鼠;取全血测量AChE活性。结果 停留在热环境（38℃/40℃）中的小鼠活动量明显增加,烦躁不安、勤梳毛发,口周及下腹部毛发湿润,阴囊变大,摄水量降低。热环境前后小鼠平均体重差值38℃组是40℃组的0.69倍（P<0.05）;而热环境前后体重百分比是20℃体重变化百分比的96.49%和95.78%,有显著差异（P<0.05）。热应激有机磷毒物中毒组小鼠全血AChE活力明显下降（P<0.05）。在本实验条件下,空白对照组,小鼠全血AChE活力在38℃时最高（91±10)kU·L^-1,40℃时最低（57±3)kU·L^-1,三个温度组之间有显著差异（P<0.05）;在同一温度组,随着染毒剂量的增加,小鼠全血AChE的活力逐渐降低;各温度组,与空白对照组相比,有机磷毒物9和15 mg·kg^-1组均有显著差异（P<0.05）;而有机磷毒物15 mg·kg^-1组与各温度空白对照组都有显著降低（P<0.05）。提示温度改变或有机磷毒物单因素作用时,对小鼠全血AChE活力均有显著影响,且温度和有机磷毒物对小鼠全血AChE活力的影响有交互作用;40℃热应激和有机磷毒物15 mg·kg^-1时小鼠全血AChE活力最低。结论 热应激或有机磷毒物中毒对小鼠AChE有显著的抑制作用,指标的变化幅度远大于单纯有机磷毒物中毒的效应,温度和染毒剂量对小鼠全血AChE的影响有交互作用。     

对氧磷酶2研究进展

<正>对氧磷酶(paraoxonase,PON)基因家族包含3个高度保守的基因:PON1基因、PON2基因与PON3基因,它们都位于染色体7q21.3-22.1区域,三者具有高度的同源性。由于PON2独特的表达特性和分布特性,近年来的研究热点聚焦于此。与PON1和PON3不同,PON2在人体的诸多组织具有表达,包括:肝脏、肾脏、肺脏、心脏、胎盘、睾丸、胃、脾脏、胰腺、小肠、骨骼肌、动脉壁细胞以及巨噬细胞。尽管PON2具有与PON1高度同源的氨基酸序列和相似的结     

对氧磷酶-1与有机磷农药中毒的关系

1953年,人们发现生物体内存在一种能水解神经毒杀虫剂的有机化合物--对氧磷（paraoxon）的酶类,称为对氧磷酶（paraoxonase,PON）.其对有机磷农药中毒的治疗具有重要作用,下面就这方面进展作一综述.     

对硫磷与对氧磷抑制的人脑乙酰胆碱酯酶的老化及重活化

目的　了解对硫磷与对氧磷在试管内对人脑乙酰胆碱酯酶 (AChE)的抑制 ,膦酰化酶的老化速率及肟类药物的重活化效能有何差别。方法　微量羟胺比色法测定AChE活性。结果　对硫磷与对氧磷抑制人脑AChE 5 0 %活性的摩尔浓度的负对数值(pI50 )分别为 4 .10及 7.5 1,抑制人脑AChE 90 %活性的摩尔浓度的负对数值 (pI90 )值分别为 2 .5 5及6 .5 7。氯磷定、双复磷、双磷定和酰胺磷定 4种重活化剂对对硫磷与对氧磷抑制的人脑AChE的重活化作用有较大差异 ,等摩尔浓度条件下 ,其对对氧磷的重活化作用普遍好于对硫磷。且双肟类重活化剂作用普遍强于单肟类重活化剂 ;对硫磷与对氧磷的最佳重活化剂均为双复磷。对硫磷与对氧磷人脑AChE磷酰化酶的半老化时间 (t0 .5)分别为 14及 12h ,老化达到 99%的时间 (t0 .99)分别为 95及 81h。结论　对硫磷或对氧磷中毒时应尽早使用双复磷或双磷定。且在急性中毒症状控制后 ,仍须连续使用重活化剂 4d。     

对氧磷酶基因家族与动脉粥样硬化

对氧磷酶基因家族至少有PON1、PON2和PON33个成员。PON1的活性与动脉粥样硬化呈负相关,其遗传多态性可能是As的独立危险因素。PON2和PON3在结构及功能上与PON1高度相似,PON2的遗传多态性与PON1具有协同效应,PON3也是一种具有抗氧化作用的内酯酶。PON基因家族的3个成员都能通过影响HDL的功能及抑制LDL的氧化而起着抗动脉粥样硬化的作用。     

冠心病患者I型对氧磷酯酶基因192 Gln／Arg多态性的研究

目的：探讨中国北方地区I型对氧磷酯酶（paraoxonase,PON1)基因192 Gln/Arg遗传多态性及其与冠心病发病的关系。方法：应用PCR－RFLP技术，检测49例老年CHD患者和38例对照者的PON1－192Gln/Arg基因多态性，等位基因以A／B表示。结果：各基因组（AA，AB，BB）分布在冠心病组：18.4%,51%,30.6%;对照组：39.5%,47.3%,13.2%。两组比较各基因型分布具有显著性差异（X^2=6.35,P=0.042);B等位基因在冠心病组明显增高（0.56vs.0.370);B等位基因携得（AB型＋B型）与AA型纯合子比较，两组间具有显著性差异（x^2=4.77,P=0.029).B等位基因是中国北方地区冠心病发病的危险因素(OR=2.19,95%CI:1.19-4.05)。结论：PON1基因192Gln/Arg遗传多态性与中国北方地区冠心病发病明显相关。该酶切位点多态性具有明显的种族差异。     

High-dose taurine supplementation increases serum paraoxonase and arylesterase activities in experimental hypothyroidism

1. Hypothyroidism is accompanied by hyperlipidaemia and oxidative stress and is associated with several complications, such as atherosclerosis. Paraoxonase activity has been reported to decrease in several situations associated with atherosclerosis and oxidative stress. In the present study, the effects of different doses of taurine on serum paraoxonase and arylesterase activities, as well as on the serum lipid profile, were investigated in hypothyroid rats. 2. Forty male Sprague-Dawley rats were randomly divided into five groups as follows: Group 1, rats received normal rat chow and tap water; Group 2, rats received standard rat chow + 0.05% propylthiouracil (PTU) in the drinking water; and Groups 3-5, taurine-supplemented PTU groups (standard rat chow + 0.5, 2 or 3% taurine in the drinking water, respectively, in addition to PTU). Paraoxon or phenylacetate were used as substrates to measure paraoxonase and arylesterase activity, respectively. Plasma and tissue malondialdehyde (MDA) levels, indicators of lipid peroxidation, were determined using the thiobarbituric-acid reactive substances method. Serum triglyceride, total cholesterol and high-density lipoprotein-cholesterol (following precipitation with dextran sulphate-magnesium chloride) were determined using enzymatic methods. 3. Serum paraoxonase and arylesterase activities were increased and plasma and tissue MDA levels and serum triglyceride levels were reduced in a dose-dependent manner in taurine-treated hypothyroid rats. Taurine concentrations were positively correlated with enzyme activities and negatively correlated with MDA and triglyceride levels. 4. Further studies are needed to investigate the role of taurine supplementation in hypothyroidism in human subjects.     

Effects of copper,zinc and paraquat on acetylcholinesterase activity in carp (Cyprinus carpio L.)

The effects of pH and substrate concentration on acetylcholinesterase (AChE) activity were studied in serum, brain, heart and muscle of common carp (Cyprinus carpio L.). Effects of zinc chloride, paraquat (1,1′-dimethyl-4,4′-dipyridinium dichloride) and copper sulphate from in vivo and in vitro exposure were studied on these AChE activities. Zinc chloride did not decrease AChE activity in any of the organs studied in vivo or in vitro. In contrast, paraquat, competitively, and copper sulphate, in a mixed way, inhibited acetylcholinesterase activity. Inhibition of AChE in fish exposed to these two pesticides may serve as an indicator of hazard due to application of these chemicals in the natural environment.     

血清对氧磷酶活性联合丙二醛在子痫前期发病中的意义

目的探讨子痫前期（PE）孕妇血清中对氧磷酶活性（PON）、丙二醛（MDA）含量与PE发病及病情轻重程度的相关性。方法选择PE患者60例作为试验组,另取健康晚孕期女性40例作为对照组。检测和观察PE孕妇血清中PON活性、MDA含量变化。结果试验组孕妇血清中PON活性（99±33）kU/L显著低于对照组（140±33）kU/L（P〈0.01）,其中重度PE组PON活性（82±30）kU/L较轻度PE组（116±27）kU/L明显降低（P〈0.01）,轻度PE组亦低于对照组（P〈0.05）。试验组孕妇血清中MDA含量（6.1±1.6）nmol/L显著高于对照组（4.4±0.9）nmol/L（P〈0.01）,其中重度PE组MDA含量（7.1±1.5）nmol/L较轻度PE组（5.2±1.0）nmol/L明显升高（P〈0.01）,轻度PE组亦高于对照组（P〈0.05）。结论PON活性、MDA含量高低与PE发病及病情轻重程度有关。     

Oxidative stress and genetic damage among workers exposed primarily to organophosphate and pyrethroid pesticides

The indiscriminate use of pesticides in agriculture and public health campaigns has been associated with an increase of oxidative stress and DNA damage, resulting in health outcomes. Some defense mechanisms against free radical‐induced oxidative damage include the antioxidant enzyme systems. The aim of this study was to determine the levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and the relationship of antioxidant enzyme levels with DNA damage among sprayers (workers) occupationally exposed to pesticides. The determinations of MDA and antioxidant enzymes were performed spectrophotometrically. The genotoxic effects were evaluated using the comet assay. The results showed a marginally significant decrease in SOD and CAT activities in the high exposure group compared to the control group. For MDA, statistically significant differences were found among people working long term vs. those working temporarily (P = 0.02) as sprayers. In the moderate exposure group, a positive correlation was observed between MDA levels and GPx activity. In the high exposure group, a negative correlation was observed between GR and CAT activities, and between MDA levels and GPx activities. Furthermore, in the high exposure group, a positive correlation between DNA damage parameters and MDA levels was observed. The results suggest an important role of antioxidant enzymes for the protection of DNA damage caused by occupational exposure to pesticides.     

Selective effects of carbamate pesticides on rat neuronal nicotinic acetylcholine receptors and rat brain acetylcholinesterase

Effects of commonly used carbamate pesticides on rat neuronal nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes have been investigated using the two-electrode voltage clamp technique. The potencies of these effects have been compared to the potencies of the carbamates to inhibit rat brain acetylcholinesterase. The potency order of six carbamates to inhibit alpha4beta4 nicotinic receptors is fenoxycarb > EPTC > carbaryl, bendiocarb > propoxur > aldicarb with IC50 values ranging from 3 microM for fenoxycarb to 165 microM for propoxur and >1 mM for aldicarb. Conversely, the potency order of these carbamates to inhibit rat brain acetylcholinesterase is bendiocarb > propoxur, aldicarb > carbaryl > EPTC, fenoxycarb with IC50 values ranging from 1 microM for bendiocarb to 17 microM for carbaryl and > mM for EPTC and fenoxycarb. The alpha4beta2, alpha3beta4, and alpha3beta2 nicotinic acetylcholine receptors are inhibited by fenoxycarb, EPTC, and carbaryl with potency orders similar to that for alpha4beta4 receptors. Comparing the potencies of inhibition of the distinct subtypes of nicotinic acetylcholine receptors shows that the alpha3beta2 receptor is less sensitive to inhibition by fenoxycarb and EPTC. The potency of inhibition depends on the carbamate as well as on a combination of alpha and beta subunit properties. It is concluded that carbamate pesticides affect different subtypes of neuronal nicotinic receptors independently of acetylcholinesterase inhibition. This implicates that neuronal nicotinic receptors are additional targets for some carbamate pesticides and that these receptors may contribute to carbamate pesticide toxicology, especially after long-term exposure.     

Effects of waterborne acephate exposure on antioxidant responses and acetylcholinesterase activities in Synechogobius hasta

The present study was conducted to determine the 24, 48, 72, and 96‐h median lethal concentration (LC50) of acephate and investigate the antioxidant response and acetylcholinesterase (AChE) activities in liver, gill, and spleen of Synechogobius hasta exposed to 0 (control), 5, and 10 mg/L acephate, at the fixed interval time of 24, 48, 72, and 96 h, respectively. LC50 value was 60.83 mg/L at 24 h, 51.36 mg/L at 48 h, 47.07 mg/L at 72 h and 40.13 mg/L at 96 h, respectively. Dismutase (SOD), catalase (CAT), AChE activities, and malondialdehyde (MDA) levels in these tissues for the control remained stable over the exposure period. However, for the two tested groups, tissue‐, dose‐, and time‐dependent responses of these parameters were observed in S. hasta. In general, hepatic SOD and CAT activities were significantly inhibited at 24 h, activated, and increased at 48 h, but again inhibited from 48 to 96 h in fish exposed to the two tested concentrations. Hepatic MDA levels of fish for the two tested concentration peaked at 48 h, significantly higher than the control. Hepatic AChE activity was inhibited at 24 h, peaked at 48 h, and then declined at 72 h for the two tested groups. For gills, the highest SOD and CAT activities for the two tested groups were observed at 48 h, higher than the control. AChE activities for the two tested groups were significantly inhibited at 24 h, but activated at 48 h. At 96 h, AChE activities among the treatments showed no significant differences. Gill MDA levels at 48 h for the tested groups were significantly higher than the control, but showed no significant differences at 24 and 72 h among the treatments. In spleen, SOD and CAT activities at 48 h for the two tested groups were significantly higher than those in the control, but at 96 h the vice versa was true. Spleenic AChE activities and MDA levels for the two tested groups were inhibited at 24 h, activated at 48 h, and then were again inhibited at 72 h. Based on these observations earlier, the results obtained in our study will have important toxicological implications for waterborne acephate pollution and, meantime, provide the basis for the effective risk assessment of acephate in water environment and appropriate safety recommendations for fish. © 2011 Wiley Periodicals, Inc. Environ Toxicol 2013.     

Paraoxonase-1 genetic polymorphisms and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides

Human paraoxonase 1 (PON1) is a lipoprotein-associated enzyme involved in the detoxification of organophosphate pesticides (OPs) by hydrolyzing the bioactive oxons. Polymorphisms of the PON1 gene are responsible for variation in the expression and catalytic activity of PON1 enzyme. In the present study, we have determined (a) the prevalence of two common PON1 polymorphisms, (b) the activity of PON1 and acetylcholinesterase enzymes, and (c) the influence of PON1 genotypes and phenotypes variation on DNA damage in workers exposed to OPs. We examined 230 subjects including 115 workers exposed to OPs and an equal number of normal healthy controls. The results revealed that PON1 activity toward paraoxon (179.19 ± 39.36 vs. 241.52 ± 42.32 nmol/min/ml in controls) and phenylacetate (112.74 ± 17.37 vs. 134.28 ± 25.49 μmol/min/ml in controls) was significantly lower in workers than in control subjects (p < 0.001). No significant difference was observed in the distribution of genotypes and allelic frequencies of PON1₁₉₂QR (Gln/Arg) and PON1₅₅LM (Leu/Met) in workers and control subjects (p > 0.05). The PON1 activity toward paraoxonase was found to be significantly higher in the R/R (Arg/Arg) genotypes than Q/R (Gln/Arg) and lowest in Q/Q (Gln/Gln) genotypes in both workers and control subjects (p < 0.001). For PON1₅₅LM (Leu/Met), PON1 activity toward paraoxonase was observed to be higher in individuals with L/L (Leu/Leu) genotypes and lowest in individuals with M/M (Met/Met) genotypes in both groups (p < 0.001). No influence of PON1 genotypes and phenotypes was seen on the activity of acetylcholinesterase and arylesterase. The DNA damage was observed to be significantly higher in workers than in control subjects (p < 0.05). Further, the individuals who showed least paraoxonase activity i.e., those with (Q/Q [Gln/Gln] and M/M [Met/Met]) genotypes showed significantly higher DNA damage compared to other isoforms in workers exposed to OPs (p < 0.05). The results indicate that the individuals with PON1 Q/Q and M/M genotypes are more susceptible toward genotoxicity. In conclusion, the study suggests wide variation in enzyme activities and DNA damage due to polymorphisms in PON1 gene, which might have an important role in the identification of individual risk factors in workers occupationally exposed to OPs.     

Inhibition kinetics of certain organophosphorus and carbamate pesticides on acetylcholinesterase from the snail Lymnaea acuminata

k2, Kd and ki, for 2 organophosphorus (Phorate and Formothion) and 2 carbamate pesticides (Mexacarbate and Carbaryl) using acetylcholinesterase present in homogenates of the nervous tissue of the snail Lymnaea acuminata, were determined. Calculation of zero time velocities demonstrated that even in their P-S form the organophosphate compounds inhibited snail acetylcholinesterase. The kinetic constants of the 2 carbamates have been explained on the basis of their structure. The toxicity of the 4 pesticides has been explained on the basis of their kinetic constants.     

人血清对氧磷酶的部分纯化及解毒效应

目的　寻求对氧磷酶 (paraoxonase ,EC 3.1.8.1)作为外源性抗毒剂对抗G类有机磷毒剂的可能性。方法　采用亲和凝胶柱层析进行了人血清对氧磷酶的部分纯化 ,测定了其对于不同底物的米氏常数 (Km)以及钙离子对于酶活性的影响 ,比较了不同种属的对氧磷酶活性 ,采用体外解毒 ,体内染毒的方法检测了对氧磷酶对于不同的底物的作用。结果部分纯化的对氧磷酶对于梭曼和对氧磷均有较好的催化水解作用。以对氧磷为底物时 ,Km 值为 0 .2 2mmol·L- 1,比活性为 375 μmol·min- 1·g- 1蛋白 ;以梭曼为底物时 ,Km 值为 0 .6 0mmol·L- 1,比活性为 4 34μmol·min- 1·g- 1蛋白。不同种属来源的血清对氧磷酶的活性差异较大 ,是造成不同种属动物对有机磷毒剂中毒敏感性差别的原因之一。部分纯化的对氧磷酶在含 1mmol·L- 1CaCl2 的缓冲液中活性良好 ,加入乙二胺四乙酸 (EDTA)后 ,无论以对氧磷或梭曼为底物 ,酶活性均受到明显抑制 ,表明人血清对氧磷酶是钙离子依赖性酶。EDTA的pI50 约为 1.8mmol·L- 1。人血清对氧磷酶能有效地水解对氧磷、梭曼、沙林、塔崩及敌敌畏 ,但对VX及乐果无效 ,表明其对P F、P CN及P O键有选择性 ,对P S键无作用。结论　对氧磷酶可作为G类毒剂的抗毒剂