Universität zu Köln

Oliveira, Eugenio E., Schleicher, Sabine, Bueschges, Ansgar, Schmidt, Joachim, Kloppenburg, Peter and Salgado, Vincent L. (2011). Desensitization of nicotinic acetylcholine receptors in central nervous system neurons of the stick insect (Carausius morosus) by imidacloprid and sulfoximine insecticides. Insect Biochem. Mol. Biol., 41 (11). S. 872 - 881. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 0965-1748

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Abstract

Imidacloprid, sulfoxaflor and two experimental sulfoximine insecticides caused generally depressive symptoms in stick insects, characterized by stillness and weakness, while also variably inducing postural changes such as persistent ovipositor opening, leg flexion or extension and abdomen bending that could indicate excitation of certain neural circuits. We examined the same compounds on nicotinic acetylcholine receptors in stick insect neurons, which have previously been shown to desensitize in the presence of ACh. Brief U-tube application of 10(-4) M solutions of insecticides for 1 s evoked currents that were much smaller than ACh-evoked currents, and depressed subsequent ACh-evoked currents for several minutes, indicating that the compounds are low-efficacy partial agonists that potently desensitize the receptors. Much lower concentrations of insecticides applied in the bath for longer periods did not activate currents, but inhibited ACh-evoked currents via desensitization of the receptors. Previously described fast- and slowly-desensitizing nACh currents, I-Ach1 and IAch(2) respectively, were each found to consist of two components with differing sensitivities to the insecticides. Imidacloprid applied in the bath desensitized high-sensitivity components, I-ACh1H and I-ACh2H with IC(50)s of 0.18 and 0.13 pM, respectively. It desensitized the low-sensitivity slowly desensitizing component. I-ACh2L, with an IC50 of 2.6 nM, while a component of the fast-desensitizing current, IACh1L, was least sensitive, with an IC50 of 81 nM I-ACh1L appeared to be insensitive to the three sulfoximines tested, whereas all three sulfoximines potently desensitized I-ACh1H and both slowly desensitizing components, with IC(50)s between 2 and 7 nM. We conclude that selective desensitization of certain nAChR subtypes can account for the insecticidal actions of imidacloprid and sulfoximines in stick insects. (C) 2011 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Oliveira, Eugenio E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schleicher, Sabine UNSPECIFIED UNSPECIFIED UNSPECIFIED Bueschges, Ansgar UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Joachim UNSPECIFIED UNSPECIFIED UNSPECIFIED Kloppenburg, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED Salgado, Vincent L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-486417
DOI:	10.1016/j.ibmb.2011.08.001
Journal or Publication Title:	Insect Biochem. Mol. Biol.
Volume:	41
Number:	11
Page Range:	S. 872 - 881
Date:	2011
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	0965-1748
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language COCKROACH NEURONS; DROSOPHILA-MELANOGASTER; MOTONEURONAL ACTIVITY; DIVERSE ACTIONS; NEONICOTINOIDS; SPINOSAD; WALKING; TARGET; MODE; NEREISTOXIN Multiple languages Biochemistry & Molecular Biology; Entomology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48641