作用于GABA受体杀虫剂药理学

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4 Spinosad (多杀菌素)
Insects
exposed to spinosad exhibit classical symptoms of neurotoxicity, including lack of coordination, prostration, tremors, and other involuntary muscle contractions leading to paralysis and death.
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4 Spinosad (多杀菌素)
Spinosad
is a natural fermentation product produced by the actinomycete bacterium, Saccharopolyspora spinosa. It has insecticidal activity and has a structure consisting of a large complex hydrophobic ring, a basic amine group, and two sugar moieties.
Spinosad
depolarizes insect neurons by activating nicotinic receptors，causing widespread hyperactivity in the nervous system．Spinosad also act at γaminobutyric acid recepors by inhibiting γ-aminobutyric acid recepors to lead neurons hyperactive．
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3. Avermectin
Animal
toxicity Abamectin can be considered to be a specifically neurotoxic substance via opening of GABA-controlled chloride channels.
Fipronil
is a highly active, broadspectrum insecticide from the phenyl pyrazole(吡唑) family. It can be used against major lepidopterous and orthopterous pests on a wide range of field and horticultural crops and against coleopterous larvae in soil. It is also employed for cockroach and ant control.
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2、 fipronil
Insect
specificity relative to mammals is the result of differences in the binding affinity of fipronil to chloride channel membranes.
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9
2、 fipronil
The
mechanism of action for this insecticide appears to be the blockage of the GABA-regulated chloride channel. Fipronil acts as an insect-specific antagonist altering chloride ion flux, resulting in disruption of CNS activity and death of target insect.
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2、 fipronil
Fipronil
was discovered in 1987 and first authorized for agricultural and no-agricultural use in 1993. The major advantages include a broad spectrum of activity, lack of crossresistance with existing commercial products, and selectivity against pest species.
2、 fipronil
Animal
toxicity The genotoxicity studies showed no mutagenic potential. No cases of adverse health effects in humans have been reported for fipronil.
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3. Avermectin

阿维菌素，英文名称为Avermectin，是一 种新型农畜两用抗生素，属大环内酯抗生 素类杀虫杀螨剂，是土壤微生物灰色链霉 素（Strentomyces avermitilis）的发酵 代谢产物。
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3. Avermectin

作用机理：Avermectins作用于昆虫神经 元突触或神经肌肉突触的GABA-A受体， 激发神经未梢放出神经传递抑制剂γ-氨基 丁酸(GABA)，促使GABA门控的氯离子通 道延长开放，对氯离子通道具有激活作用， 大量氯离子涌入造成神经膜电位超级化， 致使神经膜处于抑制状态，从而阻断神经 未梢与肌肉的联系，使昆虫麻痹、拒食、 死亡。
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4 Spinosad (多杀菌素)
Bio-insecticide
spinosad is a novel insecticide which shows the special neurotoxic poisoning symptom with an elevation of the body， involuntary muscle contractions and tremors，eventually prostrate and paralyzed．
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3. Avermectin
Animal
toxicity The acute oral toxicity is high with LD50 values from 1.5mg/Kg bw in rats to 85mg/Kg bw in duck with mainly neurotoxic symptoms. No evidence of oncogenic potential has been found in rats and mice. Avermectins exhibit no genotoxic or mutagenic potential.
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3. Avermectin
Avermectins
are a new family of insecticidal, acaricidal, and antihelminthic(驱肠虫的) agents that have been isolated from fermentation products of Streptomyces avermitilis.
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4 Spinosad (多杀菌素)
Although
the mode of action of spiosad is not fully understood, it appears to affect nicotinic and GABA-receptor function.
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4 Spinosad (多杀菌素)
第六章 作用于GABA受体杀虫剂
1、
GABA-receptor GABA (γ-aminobutyric acid ) is a true neurotransmitter. GABA's role is that of the primary inhibitory neurotransmitter. GABA achieves this by effecting the actions of the GABA receptor, a 5 subunit ion transporter.
was developed for agricultural use. It is composed of 80 per cent avermectin B 1a and 20 per cent avermectin B 1b.
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3. Avermectin
The
related substance, ivermectin, was introduced into human medicine mainly for use against Onchocerca volvulus (盘尾丝虫)and also into veterinary medicine against animal parasites.
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3. Avermectin
These
complex macrocyclic disaccharides have shown biological activity against insects, nematodes, and arthropods.
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3. Avermectin
Abamectin
1
1. GABA-receptor
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1. GABA-receptor
3
1. GABA-receptor
4
1. GABA-receptor
5
1. GABA-receptor
When
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GABA binds to the GABA receptor, the subunits of the receptor "open" and there is an influx of chloride ions. This influx restores the electrical potential of the neuron and thereby decreases the likelihood that the neuron will depolarize and relay the incoming signal. Essentially, weak or irrelevant signals are more likely to be terminated or "ignored."
Fra Baidu bibliotek20
3. Avermectin
Since
commercially available abamectin formulations of pesticides contain only a low amount of the active ingredient, severe intoxications are only possible if relatively large quantities of the formulation are ingested.
2、 fipronil
fipronil ） 法国罗纳普朗克公司开发的苯并吡唑 类杀虫剂，中等毒性，以触杀、胃毒 为主，在水稻上内吸作用强，主要防 水稻螟虫、飞虱、蓟马、蚜虫、小菜 蛾等，对有机磷和菊酯类杀虫剂抗性 害虫的防治效果较好。
2、锐劲特（regent,氟虫腈
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2、 fipronil
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4 Spinosad (多杀菌素)
Spinosad
has proven effective in controlling many chewing insect pests with such high selectivity that more than 70 per cent of beneficial insects and predatory wasps are left unharmed.
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4 Spinosad (多杀菌素)
Spinosad
is composed of numerous spinosyns, but nearly all of the insecticidal activity of spinosad is produced by the two closely related compounds spinosyns A and D, in a ratio of approximately 7:1.