Cyclodiene insecticides release labeled neurotransmitter in striatal and cortical synaptosome preparations under nondepolarizing conditions, typically showing half-maximal potencies for release in the low micromolar range. This level of potency is similar to those reported for inhibition of 36Cl- influx at the gamma-aminobutyric acid (GABA)(A) receptor, their consensus target site. A wide variety of other GABA(A) antagonists, including picrotoxinin and bicuculline, did not cause significant dopamine release, which obviated direct involvement of the GABA(A) receptor as a possible site of action. Release assays with different transmitters indicated that striatal dopaminergic terminals are severalfold more sensitive to release than other neurotransmitter types. The selective sensitivity of nigrostriatal dopaminergic nerve terminals to insecticidal organochlorines provides biochemical evidence supporting an epidemiological linkage between exposure to environmental toxicants and Parkinsonism.
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http://dx.doi.org/10.1006/taap.2002.9405 | DOI Listing |
Pestic Biochem Physiol
August 2024
Virginia Polytechnic Institute and State University, Department of Entomology, Molecular Physiology and Toxicology Laboratory Blacksburg, VA 24061, USA; School of Neuroscience, Fralin Life Science Institute, Virginia Tech Center for Drug Discovery, Center for Emerging Zoonotic and Arthropod-borne Diseases, Virginia Tech, Blacksburg, VA 24061, USA. Electronic address:
The Drosophila melanogaster MD-RR strain contains an Rdl mutation (A301S) resulting in resistance to several insecticide classes viz. phenyl pyrazoles (e.g.
View Article and Find Full Text PDFInsects
May 2024
Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China.
Ionotropic γ-aminobutyric acid (GABA) receptors in insects, specifically those composed of the RDL (resistant to dieldrin) subunit, serve as important targets for commonly used synthetic insecticides. These insecticides belong to various chemical classes, such as phenylpyrazoles, cyclodienes, meta-diamides, and isoxazolines, with the latter two potentially binding to the transmembrane inter-subunit pocket. However, the specific amino acid residues that contribute to the high sensitivity of insect RDL receptors to these novel insecticides remain elusive.
View Article and Find Full Text PDFPest Manag Sci
April 2024
Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Background: Insect RDL (resistant to dieldrin) receptors are essential pentameric ligand-gated chloride channels that mediate the neuroinhibitory effect of GABA, the chief inhibitory neurotransmitter in the central nervous system. These receptors serve as primary targets for various insecticides, including noncompetitive antagonists (NCAs) such as cyclodiene organochlorines and phenylpyrazoles, as well as allosteric modulators like meta-diamides and isoxazolines. This study focuses on a newly discovered A2'N mutation within the RDL receptors, identified in fipronil-resistant planthoppers.
View Article and Find Full Text PDFPestic Biochem Physiol
August 2023
Department of Tropical Medicine and Parasitology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea. Electronic address:
Pyrethroids are primarily used for mosquito control in Korea. However, high frequencies of mutations conferring resistance to not only pyrethroids but also to other insecticides have been found in mosquito populations. This study aimed to examine the hypothesis that insecticides used outside of public health may play a role in selection.
View Article and Find Full Text PDFPestic Biochem Physiol
October 2022
Syngenta, Bioscience, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK.
Isocycloseram is a novel isoxazoline insecticide and acaricide with activity against lepidopteran, hemipteran, coleopteran, thysanopteran and dipteran pest species. Isocycloseram selectively targets the invertebrate Rdl GABA receptor at a site that is distinct to fiproles and organochlorines. The widely distributed cyclodiene resistance mutation, A301S, does not affect sensitivity to isocycloseram, either in vitro or in vivo, demonstrating the suitability of isocylsoseram to control pest infestations with this resistance mechanism.
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