title: Use of electroencephalography (EEG) to assess CNS changes produced by pesticides with different modes of action: effects of permethrin, deltamethrin, fipronil, imidacloprid, carbaryl, and triadimefon.
abstract: The electroencephalogram (EEG) is an apical measure, capable of detecting changes in brain neuronal activity produced by internal or external stimuli. We assessed whether pesticides with different modes of action produced different changes in the EEG of adult male Long-Evans rats. The EEG was recorded using two montages (visual cortex referenced to the cerebellum and to the frontal cortex) in unrestrained rats at the time of peak behavioral effects. Pesticides included: permethrin and deltamethrin (Type I and Type II pyrethroids; 2 h), fipronil (single and repeated doses; phenylpyrazole; 6 h), imidacloprid (neonicotinoid; 2 h), carbaryl (carbamate; 0.5 h), and triadimefon (triazole; 1 h), using dosages that produced approximately an ED30 or an ED50-ED80 change in motor activity. Permethrin (43, 100 mg/kg) increased amplitudes or areas (delta, alpha, or gamma bands) in the EEG. Deltamethrin (2.5, 5.5 mg/kg) reduced the amplitudes or areas of the delta, theta, alpha, beta, and gamma bands, but the changes were not dose-related. A single treatment with fipronil (25, 50 mg/kg, but not 5, 10 mg/kg) decreased gamma band area. Additional changes in the delta, theta, and gamma bands were observed when fipronil (5, 10 mg/kg) was administered for 14 days. Imidacloprid (50, 100 mg/kg) did not alter the EEG. Carbaryl (10, 50 mg/kg) decreased theta area, and decreased delta and increased beta frequency. Triadimefon (75, 150 mg/kg) produced minimal changes in the EEG. The results show that the EEG is affected differently by approximately equipotent doses of pesticides with different modes of action.
authors.affiliation: Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, USA. Electronic address: Freeborn.danielle@epa.gov.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Freeborn
authors.affiliation: Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, USA. Electronic address: McDaniel.kathy@epa.gov.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: McDaniel
authors.affiliation: Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, USA. Electronic address: Moser.ginger@epa.gov.
authors.forename: Virginia C
authors.initials: VC
authors.lastname: Moser
authors.affiliation: Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, USA. Electronic address: Herr.david@epa.gov.
authors.forename: David W
authors.initials: DW
authors.lastname: Herr
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects*; D002800:Cholinesterase Inhibitors / Q000633:toxicity; D002802:Cholinesterases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D005659:Fungicides, Industrial / Q000633:toxicity; D007306:Insecticides / Q000633:toxicity; D008297:Male; D010575:Pesticides / Q000633:toxicity*; D051381:Rats; D020318:Rats, Long-Evans; D014793:Visual Cortex / Q000187:drug effects
chemical_list: D002800:Cholinesterase Inhibitors; D005659:Fungicides, Industrial; D007306:Insecticides; D010575:Pesticides; D002802:Cholinesterases
keywords: EEG; Pesticides; Rats