title: The actions of the neonicotinoid imidacloprid on cholinergic neurons of Drosophila melanogaster.
abstract: The neonicotinoid insecticide imidacloprid is an agonist on insect nicotinic acetylcholine receptors (nAChRs). We utilised fura-2-based calcium imaging to investigate the actions of imidacloprid on cultured GFP-tagged cholinergic neurons from the third instar larvae of the genetic model organism Drosophila melanogaster. We demonstrate dose-dependent increases in intracellular calcium ([Ca2+]i) in cholinergic neurons upon application of imidacloprid (10 nM-100 muM) that are blocked by nAChR antagonists mecamylamine (10 microM) and alpha-bungarotoxin (alpha-BTX, 1 microM). When compared to other (untagged) neurons, cholinergic neurons respond to lower concentrations of imidacloprid (10-100 nM) and exhibit larger amplitude responses to higher (1-100 microM) concentrations of imidacloprid. Although imidacloprid acts via nAChRs, increases in [Ca2+]i also involve voltage-gated calcium channels (VGCCs) in both groups of neurons. Thus, we demonstrate that cholinergic neurons express nAChRs that are highly sensitive to imidacloprid, and demonstrate a role for VGCCs in amplifying imidacloprid-induced increases in [Ca2+]i.
authors.affiliation: MRC Functional Genetics Unit, Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, OX1 3QX, Oxford, UK.
authors.forename: James E C
authors.initials: JE
authors.lastname: Jepson
authors.forename: Laurence A
authors.initials: LA
authors.lastname: Brown
authors.forename: David B
authors.initials: DB
authors.lastname: Sattelle
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004331:Drosophila melanogaster; D016257:Fura-2; D007093:Imidazoles / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D000073943:Neonicotinoids; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009574:Nitro Compounds; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D011978:Receptors, Nicotinic; C082359:imidacloprid; D000109:Acetylcholine; D016257:Fura-2