Electrophysiological biomarkers of an organophosphorous pesticide, dichlorvos.

The correlations between the relatively low level, chronic dichlorvos (DDVP) treatment and the early electrophysiological changes were investigated in three series of experiments. In the first series, male Wistar rats were orally given daily by gavage 0.98, 1.96 and 3.92 mg/kg of DDVP for 4, 8, or 12 weeks, and recordings were made at the end of each period. In the second one, the male and female rats of three consecutive generations were treated with the same doses, the investigated parameters were recorded at the age of 12 weeks of the male animals. In the third experiment, the doses were administered in different stages of development: during pregnancy, pregnancy + lactation, pregnancy + lactation + postweaning, and the electrophysiological markers were recorded also at the age of 12 weeks of male offspring. The analyzed elecrophysiological parameters were: electrocorticogram, sensoric cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve. The data showed that the relatively low level dichlorvos exposure caused dose-, duration-, generation-, developmental stage-dependent and partly significant alterations in all the investigated electrophysiological parameters. The analyzed functional parameters proved to be sensitive biomarkers of the exposure as they were changed by the lower doses, while the brain cholinesterase activity was considerably inhibited only in the groups given the highest dose.