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Neonicotinoid insecticides display partial and super agonist actions on native insect nicotinic acetylcholine receptors
Author(s) -
Brown Laurence A.,
Ihara Makoto,
Buckingham Steven D.,
Matsuda Kazuhiko,
Sattelle David B.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.04084.x
Subject(s) - clothianidin , nicotinic agonist , imidacloprid , neonicotinoid , acetylcholine , acetylcholine receptor , nicotine , pharmacology , agonist , nicotinic acetylcholine receptor , chemistry , thiacloprid , biology , neuroscience , receptor , biochemistry , thiamethoxam , pesticide , agronomy
Nicotinic acetylcholine receptors (nAChRs) are present in high density in insect nervous tissue and are targeted by neonicotinoid insecticides. Improved understanding of the actions of these insecticides will assist in the development of new compounds. Here, we have used whole‐cell patch‐clamp recording of cholinergic neurons cultured from the central nervous system of 3rd instar Drosophila larvae to examine the actions of acetylcholine (ACh) and nicotine, as well as the neonicotinoids imidacloprid, clothianidin and P‐CH‐clothianidin on native nAChRs of these neurons. Dose–response data yield an EC 50 value for ACh of 19 μ m . Both nicotine and imidacloprid act as low efficacy agonists at native nAChRs, evoking maximal current amplitudes 10–14% of those observed for ACh. Conversely, clothianidin and P‐CH‐clothianidin evoke maximal current amplitudes up to 56% greater than those evoked by 100 μ m ACh in the same neurons. This is the first demonstration of ‘super’ agonist actions of an insecticide on native insect nAChRs. Cell‐attached recordings indicate that super agonism results from more frequent openings at the largest (63.5 pS) conductance state observed.