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IMIDACLOPRID PRODUCES MINIMAL CHANGES IN THE EEG OF LONG-EVANS RATS
Citation:
LYKE, D. F., K. MCDANIEL, V. C. MOSER, AND D. W. HERR. IMIDACLOPRID PRODUCES MINIMAL CHANGES IN THE EEG OF LONG-EVANS RATS. Presented at Society of Toxicology (SOT) Annual Meeting, San Francisco, CA, March 11 - 15, 2012.
Impact/Purpose:
In the current study, we examined the ability to detect changes in EEG activity produced by imidacloprid, a neonicotinoid pesticide that binds to nicotinic acetylcholine receptors.
Description:
We have reported that the non-stimulus driven EEG is differentially altered by deltamethrin or permethrin (Lyke and Herr, Toxicologist, 114(S-1) :265, 2010) as well as fipronil (Lyke and Herr, Toxicologist, 120(S-2) :290, 2011). In the current study, we examined the ability to detect changes in EEG activity produced by imidacloprid, a neonicotinoid pesticide that binds to nicotinic acetylcholine receptors. Adult male Long-Evans rats were dosed with imidacloprid (po). A range-finding study (n=4/dosage: 50, 100, or 200 mg/kg in 0.5% methycellulose / 0.4% Tween 80, v:v; 1 ml/kg) was conducted using observations of neurological sign. The data suggested decreased open field rearing and mild to moderate tremors at 100 mg/kg or greater. Maximal effects were evident about 2 hours after dosing. Additional rats were implanted with epidural screw electrodes. After about 1 week recovery, non-restrained animals were gavaged with vehicle and tested for 2 days for acclimation. On day 3, the rats were dosed with vehicle, 50, or 100 mg/kg imidacloprid (n=14-15/dosage) and tested 2 h later. EEG was recorded as 30 segments of 2 s durations, transformed using a FFT, and the spectra averaged. Treatment with either 50 or 100 mg/kg imidacloprid did not significantly alter the EEG spectra. A decrease in alpha amplitude and area (particularly between the visual cortex and frontal cortex; 35-19% decrease) had approximately 40% power for detection at the p=0.05 level. Approximately 23-57 animals/dosage would be required to detect these differences with 80% power. These results were different from the decreased gamma activity resulting from treatment with fipronil, increased gamma activity following treatment with permethrin, but similar to the lack of EEG changes after dosing with deltamethrin. The data show that imidacloprid produced minimal changes in CNS activity as measured by EEG, and the alterations may differ from some other pesticides. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.