Effects of oral tetrachlorvinphos fly control (Equitrol®) administration in horses: Physiological and behavioural findings

Highly reactive horses may pose risks to humans involved in equestrian activities. Among the factors that may affect horses’ reactivity to external stimuli are pesticides used for fly control in equine facilities. The organophosphorus (OP) insecticide tetrachlorvinphos (TCVP) is used as a feed-through larvicide to prevent completion of the fly larval life cycle in horse manure. TCVP exerts its effect by inhibiting the enzyme cholinesterase (ChE) leading to the accumulation of the neurotransmitter acetylcholine (AChE) in synapses of the central and peripheral nervous systems. The aim of the present study was to investigate alterations of whole-blood ChE levels associated with feeding a commercially available product (Equitrol, Farnam Companies, Inc.) to horses for fly control. A second aim was to report neurological, physiological and behavioural findings in addition to profiles of selected immune markers (IFN-γ, IL-12p40 and COX-2) and serum thyroid hormones during and after a 30-day treatment period of TCVP feeding. The results indicated significant decreases in whole-blood ChE activity and concomitant behavioural alterations, manifested as increased reactivity and decreased controllability in treated horses. No changes were detected in physiological or neurological parameters, immune markers or thyroid hormones in treated (n = 6) or control (n = 4) horses during the course of the study.     

赤拟谷盗乙酰胆碱酯酶生化及毒理学特性研究

为了阐明赤拟谷盗[Triboliumcastaneum(Herbst)]体内乙酰胆碱酯酶(AChE)在其各虫态间的变化关系,以期为该虫的综合治理提供一定的理论依据,本试验采用微量滴度酶标板法,分别对其10d龄和20d龄幼虫、蛹及成虫体内AChE的生化及毒理学特性进行了较为系统的研究。结果表明,赤拟谷盗各虫态AChE酶源蛋白含量、酶活力和比活力差异显著,酶源蛋白含量从低到高依次为:10d龄幼虫<20d龄幼虫<成虫<蛹;AChE活力和比活力依次为:成虫<蛹<10d龄幼虫<20d龄幼虫。酶动力学分析发现,AChE米氏常数Km值大小依次为:蛹<成虫<10d龄幼虫<20d龄幼虫,但成虫和蛹之间的差异不显著。此外,幼虫AChE的最大反应速度Vmax亦显著高于成虫和蛹。通过对幼虫AChE离体抑制作用测定表明,毒扁豆碱、马拉氧磷和西维因对20d龄幼虫的抑制中浓度I50均高于10d龄幼虫,说明20d龄幼虫体内的AChE对3种抑制剂的抑制作用更不敏感。     

昆虫乙酰胆碱酯酶研究进展

昆虫乙酰胆碱酯酶(AChE)是昆虫体内神经传导的一种关键酶,是有机磷类和氨基甲酸酯类农药的重要作用靶标。介绍了昆虫AChE研究的历史和现状,并分别从昆虫AChE的分子特性、ace基因、昆虫抗药性和农药残留检测4个方面进行了探讨,以期为昆虫AChE的深入研究提供理论依据。     

Substrate specificity of brain acetylcholinesterase and its sensitivity to carbamate insecticides in <Emphasis Type="Italic">Carassius auratus</Emphasis>

The substrate specificity of brain acetylcholinesterase (AChE) in adult Carassius auratus fish and its sensitivity to carbamate insecticides were investigated in vitro. The results showed that the order of four substrates hydrolyzed by brain AChE in C. auratus was acetylthiocholine iodide > β-methylthiocholine iodide > propionylthiocholine iodide > butyrylthiocholine iodide, and the maximum velocity (V _max) of AChE hydrolyzing acetylthiocholine iodide (ATCh) was the highest among the four substrates, and the V _max values were 0.067 and 0.082 mmol min⁻¹ mg⁻¹ for male and female fish respectively. But their Michaelis–Menten constants (K _m) were the lowest, only 0.071 and 0.072 mmol/l respectively. Compared with other carbamate insecticides, the sensitivity of brain AChE to carbofuran was the highest and the IC₅₀ values were 1.04 × 10⁻⁶ mol/l for females and 1.17 × 10⁻⁶ mol/l for males. The inhibitory tendencies of eserine, methomyl, and aldicarb to brain AChE were very similar, and the percentage inhibition increased with time at the concentration of 1 × 10⁻⁶ mol/l. The order of inhibition potential of the three inhibitors from the highest to the lowest was eserine, aldicarb, and methomyl.     

Cholinesterase (ChE) inhibition in pumpkinseed (Lepomis gibbosus) as environmental biomarker: ChE characterization and potential neurotoxic effects of xenobiotics

Inhibition of cholinesterases (ChEs) has been widely used as an environmental biomarker of exposure to organophosphates (OP) and carbamate (CB) pesticides. More recently, this biomarker has been suggested as a putative biomarker for exposure to detergents. The use of cholinesterase inhibition as effect criterion in Ecotoxicology requires the previous characterization of the specific enzymatic forms that may be present in different tissues or organs. Different ChEs isoforms may be present in the same tissue and may exhibit distinct sensitivities towards environmental contaminants. This work intended to characterize the soluble ChEs present in pumpkinseed sunfish (Lepomis gibbosus) total head and dorsal muscle homogenates, through the use of different substrates and selective inhibitors of cholinesterasic activity. Also, the in vitro effects of sodium dodecylsulphate (SDS - anionic detergent) and chlorfenvinphos (organophosphate pesticide) on the enzymatic activity of the mentioned species were investigated. In general terms, the predominant cholinesterasic form present in both tissues was acetylcholinesterase. Chlorfenvinphos was responsible for inhibitory effects on AChE activity, while SDS did not cause any significant effect. These results suggest that in environmental monitoring programs, L. gibbosus head and dorsal muscle AChE can be an adequate diagnostic tool for exposure to OP pesticides; this conclusion however is not applicable to detergent residues. We also discuss the usefulness of L. gibbosus as an alternative model system and valuable option for freshwater ecotoxicological monitoring programs.     

氧化乐果对静水椎实螺急性毒性和酶活性的影响

[目的]探究有机磷农药氧化乐果对水生生物的毒性效应。[方法]测定了氧化乐果对静水椎实螺(Lymnaea stagnalis)的急性毒性,并研究了氧化乐果对静水椎实螺组织中乙酰胆碱酯酶(AChE)和超氧化物歧化酶(SOD)活性的影响。[结果]氧化乐果对静水椎实螺的96 h-LC50为19.22 mg/L,安全浓度为1.92 mg/L。静水椎实螺暴露于氧化乐果中5 d,AChE活性明显下降,SOD活性在0.53、1.06mg/L浓度下上升不明显,在2.65、5.30 mg/L浓度下呈明显下降。[结论]为氧化乐果的使用和及其污染防治提供了理论依据。     

Fumigant and contact toxicity of Myrtaceae plant essential oils and blends of their constituents against adults of German cockroach (Blattella germanica) and their acetylcholinesterase inhibitory activity

Fumigant and contact toxicities of 11 Myrtaceae plant essential oils and their constituents against adult male and female Blattella germanica were evaluated. Of 11 Myrtaceae plant essential oils, Eucalyptus polybractea, Eucalyptussmithii, Eucalyptusradiata, Eucalyptusdives, Eucalyptusglobulus, and Melaleuca uncinata, showed 100% fumigant toxicity against adult male German cockroaches at a concentration of 7.5 mg/liter air concentration. In contact toxicity tests, E. polybractea, E. smithii, E. radiata, E. dives, E. globulus, Melaleucadissitiflora, and M. uncinata produced strong insecticidal activity against adult male and female German cockroaches. Of the essential oil constituents, terpinolene, α-terpinene, and terpinen-4-ol demonstrated strong fumigant toxicity against adult male and female B. germanica. Eugenol, isoeugenol, methyl eugenol, and terpinen-4-ol showed strong contact toxicity against adult male B. germanica. The toxicity of the constituent blends identified from M. dissitiflora essential oils indicated that terpinen-4-ol were major contributor to the fumigant activity or contact toxicity of the artificial blend. Only isoeugenol exhibited inhibition activity against male acetylcholinesterase. IC₅₀ values of isoeugenol were 0.22 mg/mL against male acetylcholinesterase.     

远志茯苓醇提物改善学习记忆障碍的实验研究

目的通过观察中药远志茯苓醇提物对学习记忆障碍动物模型的影响,研究其改善学习记忆障碍的药理作用,并探讨其作用机制,为中药远志茯苓能够预防和治疗老年性痴呆即阿尔茨海默病提供可靠的依据.方法通过避暗法观察远志茯苓醇提物对东莨菪碱所致记忆获得性障碍模型小鼠的影响;通过跳台法观察远志茯苓醇提物对30%乙醇所致记忆再现障碍模型小鼠的影响;通过Morris水迷宫法观察远志茯苓醇提物对戊巴比妥钠所致空间方向辨别障碍模型小鼠的影响;应用放射免疫分析方法测定东莨菪碱所致记忆获得障碍模型小鼠血清和脑组织中乙酰胆碱酯酶的含量.结果远志茯苓醇提物能减少东莨菪碱所致记忆获得障碍模型小鼠5 min内学习及记忆实验的错误次数,延长潜伏期;能减少30%乙醇所致记忆再现障碍模型小鼠5 min内进入暗室内的次数（错误次数）,延长进入暗室的潜伏期;能缩短戊巴比妥钠所致空间方向辨别障碍模型小鼠在空间搜索实验中第一次到达原平台所在位置的时间,并增加穿越原平台的次数;能有效降低东莨菪碱所致记忆获得性障碍模型小鼠血清和脑组织中乙酰胆碱酯酶的含量.结论远志茯苓醇提物能改善多种化学药物所致学习记忆障碍模型小鼠的学习记忆能力,可能通过抑制乙酰胆碱酯酶合成,减少乙酰胆碱水解,提高血清和脑内乙酰胆碱水平而发挥改善学习记忆的作用.     

乙酰胆碱酯酶酶抑制法快速检测农药残留的研究进展

概述了乙酰胆碱酯酶酶抑制法快速检测农药残留技术的研究现状．指出了酶抑制法在使用中存在的问题和发展趋势。     

λ-cyhalothrin and cypermethrin induced in vivo alterations in the activity of acetylcholinesterase in a freshwater fish, Channa punctatus (Bloch)

In the present study, the in vivo effects of λ-cyhalothrin and cypermethrin on the activity of acetylcholinesterase (AChE, EC 3.1.1.7) were evaluated for 96 h in brain, muscle and gills of Channa punctatus. Both compounds exhibited tissue specific as well as dose dependent decrease in the activity of AChE. The treated fish showed a significant decrease in the activity of AChE in brain and a lesser inhibition in muscle and gills in response to the increasing concentrations of λ-cyhalothrin as well as cypermethrin. Our results indicated that the brain was the main target organ for both insecticides, followed by muscle and gills, as determined by AChE inhibition study. However, these organs showed variations in the degree of AChE inhibition for separate treatments of both insecticides. The λ-cyhalothrin was a more potent AChE inhibitor as compared to cypermethrin. These findings indicated that apart from the established mechanism of delayed closure of sodium ion channels, these pyrethroids inhibit the activity of AChE in C. punctatus which could further aggravate their neurotoxic effects.