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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
Citation:
Freeborn, D., Kathy Mcdaniel, V. C. Moser, AND D. Herr. 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. TOXICOLOGY AND APPLIED PHARMACOLOGY. Academic Press Incorporated, Orlando, FL, 282(2):184-94, (2015).
Impact/Purpose:
The electroencephalogram (EEG) is an apical measure,capable of detecting multiple types of changes in the brain neuronal activity produced by internal or external stimuli. The goal of this study was to assess whether pesticides with different modes of action produced different changes in the EEG of adult male Long Evans rats. Pesticides included: permethrin and deltamethrin (Type 1 and Type II pyrethroids; 2 h), fipronil (single and repeated doses; phenypyrazole;6h),imidacloprid (neonicotinoid;2h),carbaryl (carbamate;O.5h}, and triadimefon (triazole;lh},using dosages that produced a minor change in motor activity (approximately ED3o} and a larger change in motor activity (ED5o- ED8o}. Each pesticide produced a different pattern of changes in the EEG. This data shows that EEG can be used to detect changes in neurological function,and that different chemical types produced different changes in the EEG. Thus, EEG may serve as an apical measure to detect neuroactive compounds which may have little other neurotoxicity data available.
Description:
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 (neoniotinoid; 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.
