Identification of a high-affinity binding site for dinotefuran in the nerve cord of the American cockroach |
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| Authors: | Miyagi Satoshi Komaki Iori Ozoe Yoshihisa |
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| Institution: | Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan. |
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| Abstract: | The binding of the neonicotinoid insecticide dinotefuran to insect nicotinic acetylcholine receptors (nAChRs) was examined by a centrifugation method using the nerve cord membranes of American cockroaches and 3H]dinotefuran (78 Ci mmol-1). The Kd and Bmax values of 3H]dinotefuran binding were estimated to be 13.7 nM and 14.8 fmol 40 microg-1 protein respectively by Scatchard analysis. Epibatidine, an nAChR agonist, showed a rather lower affinity to the dinotefuran binding site (IC50=991 nM) than dinotefuran (IC50=5.02 nM). Imidacloprid and nereistoxin displayed lower potencies than dinotefuran but higher potencies than epibatidine. The potencies of five dinotefuran analogues in inhibiting the specific binding of 3H]dinotefuran to nerve cord membranes were determined. A good correlation (r2=0.970) was observed between the -log IC50 values of the tested compounds and their piperonyl butoxide-synergised insecticidal activities (-log LD50 values) against German cockroaches. The results indicate that a high-affinity binding site for dinotefuran is present in the nerve cord of the American cockroach and that the binding of ligands to the site leads to the manifestation of insecticidal activity. |
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| Keywords: | binding site cockroach dinotefuran neonicotinoids nicotinic acetylcholine receptors |
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