Comparison of Acute Neurobehavioral and Cholinesterase Inhibitory Effects of N-Methylcarbamates in Rat

Abstract

While the cholinesterase-inhibiting N-methyl carbamate pesti-cides have been widely used, there are few studies evaluating direct functional and biochemical consequences of exposure. In the present study of the acute toxicity of seven N-methyl carbamate pesticides, we evaluated the dose-response profiles of cholinesterase (ChE) inhibition in brain and erythrocytes (RBCs) as well as motor activity (both horizontally and vertically di-rected) and clinical signs of overt toxicity. The chemicals tested were carbaryl, carbofuran, formetanate, methiocarb, methomyl, oxamyl, and propoxur. All were administered orally, and rats were tested in 20-min activity sessions beginning 15 min after dosing; tissues were collected immediately after activity sessions. In general, motor activity was a sensitive measure of ChE inhibition for all these carbamate pesticides, and vertical activity showed the greatest magnitude of effect at the highest doses compared t