The aim of the present study was to analyse the alterations in the cortical and peripheral
electrophysiological activity of rats acutely treated with combinations of insecticides.
Young adult male Wistar rats were treated with 1/5 and 1/25 LD50 of the insecticides
dimethoate, propoxur, cypermethrin and amitraz, given alone or in triple or quadruple
combinations. After 24 h, spontaneous cortical activity, and stimulus-evoked cortical
and peripheral responses, was recorded and analysed. All treatments changed the cortical
activity spectrum. The effect of the 1/5 LD50 combinations indicated non-additive
interactions. In the cortical-evoked responses, dimethoate and its combinations gave
the strongest change in the latency, while amitraz and its combinations, in the response
duration. In the tail nerve, relative refractory period was the most sensitive parameter.
The frequency dependence of the cortical responses was the most strongly altered by
propoxur, and the least, by amitraz. Our results indicate that simultaneous exposure
by various pesticide agents, which happens possibly also in humans, deserves further
investigation in, among others, neurotoxicological points of view. ÂŠ 2006 Elsevier
Inc. All rights reserved.