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Neurotransmitters in Characean Electrical Signaling
Published in Akula Ramakrishna, Victoria V. Roshchina, Neurotransmitters in Plants, 2018
Vilma Kisnieriene, Indre Lapeikaite, Vilmantas Pupkis
Some studies have suggested that avermectin (AVM, a drug used for treating diseases caused by parasitic roundworms) can promote GABA release and bind to its receptors to result in Cl− influx, hyperpolarization of the cell membrane, and inhibition of neural cells. It is proved that the effect of avermectin B1 on neurons of mammals is due to changes in Cl− current through the GABAA receptor/Cl− ionophore complex. In addition, AVMs can induce the opening of Glu-gated Cl− channels, increase membrane Cl− permeability, and reduce nerve conduction, which results in excitotoxicity, apoptosis, and necrosis (Chen et al. 2014). It was demonstrated in voltage clamp experiments with C. corallina that avermectin A1 (but not avermectins B1, A2, B2) regulate the Ca2+-dependent Cl− currents. The low concentrations of avermectin A1 increase the Cl− currents in plant cell, while high concentrations of A1 inhibit them, thus resembling the effect of avermectin B1 on neurons of mammals. The Ca2+-dependent Cl− current in these experiments was almost completely blocked at avermectin concentration of about 10 µM and avermectin A1 concentration of 10 nM (Drinyaev et al. 2001).
Medical theory, medical care, and preventive medicine
Published in Lois N. Magner, Oliver J. Kim, A History of Medicine, 2017
Microbiologists William C. Campbell and Satoshi Ōmura discovered avermectins, a class of compounds that can kill the parasites that cause elephantiasis (lymphatic filariasis) and river blindness (onchocerciasis). Ivermectin, one of the avermectins, has revolutionized the treatment of elephantiasis and river blindness. Recognizing the great need for this drug in some of the most impoverished parts of the world, in the late 1980s Merck began donating ivermectin to people with these diseases. Of course, all pharmaceutical products are likely to have unintended consequences for some recipients. In the case of ivermectin, adverse effects have been detected among the thousands of species of dung beetles doing humble but necessary work throughout the world. Dung beetles, which are important coprophilous insects, recycle billions of tons of dung dropped by animals every day. If manure is not removed it can smother pastures and grasslands. Since the 2010s, scientists have detected a surprising threat to dung beetles that might be even more devastating than habitat loss. In addition to humanitarian use of ivermectin, the drug is a widely used veterinary drug for the control of liver flukes, eye worms, lungworms, roundworms, mites, ticks, and flies. Dung beetles are poisoned by the high concentrations of ivermectin present in animal droppings. When dung beetle populations drop, dung accumulates, as do other kinds of parasites and pests.
Issues in Fisheries and Aquaculture
Published in Joyce D’Silva, John Webster, The Meat Crisis, 2017
Sea lice, a copepod exoparasite of salmon, widely affect farmed salmon and can severely debilitate the fish unless controlled. Several chemicals based on avermectin, a class of drug used to control invertebrate parasites in animals and man, are used to control sea lice. Farmed salmon are fed the antiparasitic drug in their feed. The drug enters the fishes’ circulation and is absorbed by sea lice attached to the fish, eventually ending up in the sea. The avermectins work by disrupting nerves and affect many classes of invertebrate including crustaceans such as prawns, crabs and lobsters. Because of this, there is considerable concern about the release into the sea of these (and other) chemicals used to control sea lice. The industry is using protocols to attempt to limit releases but how effective these are is not known.
Intentional avermectin pesticide ingestion: a retrospective multicenter study
Published in Clinical Toxicology, 2022
Yi-Kan Wu, Chia-Hau Chang, Jiun-Hao Yu, Kai-Ping Lan, Tzung-Hai Yen, Shu-Sen Chang, Chen-June Seak, Hsing-Yuan Chang, Hsien-Yi Chen
Avermectins are a group of drugs initially used to treat animals with roundworms, ticks, mites, or insect infections. The primary mechanism of action of these drugs involves activation of the invertebrate glutamate-gated chloride channel and interaction with the GABA receptor, causing paralysis or death of the target pathogen. Mammalian species are much less sensitive due to lower GABA receptor affinities. Furthermore, they have GABA receptors only in the central nervous system (CNS) and are protected by the BBB [9]. Animal experiments have revealed that the existence of P-glycoprotein, an ATP-dependent transporter in the BBB, results in decreased influx and increased efflux of numerous xenobiotics, effectively lowering their intracellular concentrations and protecting mammals from avermectin-induced neurotoxicity [7,21,22]. Despite being less sensitive to avermectin, toxic effects thereof have been observed in animals [23–26]. Coma and drowsiness are common presentations in dogs and cats that overdose on avermectin. Other symptoms include dyspnea, hypotension, nausea/vomiting, neurologic signs including tremors, hyperactivity, and ataxia, and even death.
Ivermectin: a mini-review
Published in Clinical Toxicology, 2022
The avermectins are commonly used antiparasitic agents with activity against arthropods and nematodes [1]. Derived from Streptomyces bacteria found naturally in soil, the avermectin class of drugs, including abamectin, ivermectin, eprinomectin, doramectin, and selamectin, are structurally similar macrocyclic lactone compounds differentiated by the presence of A and B components [1]. Ivermectin is composed of avermectin B1 components and was initially marketed for animal use in 1981. In 1987, it was registered for human use as a treatment for onchocerciasis (river blindness) [1,2]. Currently, ivermectin is used in humans as a prescription medication for Strongyloides stercoralis, Onchocerca volvulus, and Ascariasis infections as well as lice, scabies, and rosacea.
Eprinomectin nanoemulgel for transdermal delivery against endoparasites and ectoparasites: preparation, in vitro and in vivo evaluation
Published in Drug Delivery, 2019
Yujuan Mao, Xiaolan Chen, Bohui Xu, Yan Shen, Zixuan Ye, Birendra Chaurasiya, Li Liu, Yi Li, Xiaoling Xing, Daquan Chen
As for intact skin applied with different EPR formulations, no obvious inflammation was observed, indicating that the formulations were not irritating to the intact skin of the rats (Figure 5(C)). A small amount of inflammatory cell infiltrations was found in the skin of control groups, while the damaged skin administered with EPR nanoemulsion and the EPR nanoemulgel was intact and exhibited no significant inflammation. It was reported that avermectin and its derivative ivermectin exerted anti-inflammation effect (Ci et al., 2009; Yan et al., 2011). As the EPR is the derivative of avermectin, it may also have the anti-inflammatory effect. The overall results indicated that the EPR nanoemulgel were within the limit of the skin tolerance and safe to use in transdermal applications.