A comparison of changes in spontaneous (EEG) and evoked brain activity induced by chlorphenvinphos and physostigmine in rats and rabbits.

The effects of single i.p. injections of two cholinesterase inhibitors, chlorphenvinphos (CVP) and physostigmine, on hippocampal and cortical EEG and flash evoked potentials in occipital cortex were compared in rabbits and rats. A comprised method of spectral analysis was employed for evaluation of changes in EEG. The obtained results showed that in both species the changes in hippocampal and cortical EEG after administration of CVP were relatively small or negligible in comparison with those after physostigmine administered in doses resulting in comparable (or even lesser) inhibition of blood cholinesterase (ChE). Neither CVP nor physostigmine resulted in significant changes in the morphology of the flash evoked potentials. The data do not confirm the suggestion that brain electrical activity is the most sensitive index of neurotoxicity resulting from exposure to organophosphate ChE inhibitors.