Effects of single and repeated exposures to abate on rat behavior and cholinesterase activity.

Rats were injected i.p. with the organophosphate insecticide ABATE and tested over the next 16 days. Animals given 1000 mg/kg showed impaired performance of a previously conditioned avoidance response 6 days after injection but not 2, 8, 10, or 16 days after injection. No behavioral changes were observed in animals given 316 or 562 mg/kg. A subsequent experiment showed that the avoidance impairment in animals given 1000 mg/kg was accompanied by significant erythrocyte, plasma, and brain cholinesterase activity inhibition and decreased spontaneous motor activity. If administration of the same ABATE dose was distributed over 6 days (167 mg/kg/day), cholinesterase and motor activity depression was still evident but conditioned avoidance performance was unimpaired. The results were interpreted as differential behavioral adaption to repeated injections of ABATE.