Hyperactivity and impulsiveness in rats fed diets supplemented with eitherAroclor 1248 or PCB-contaminated St. Lawrence river fish

We examined whether exposure to polychlorinated biphenyls (PCBs) around pub erty would produce hyperactivity and impulsiveness in adult Sprague-Dawley rats. Randomly assigned groups consumed food containing environmental conce ntrations of Aroclor 1248, PCB-contaminated St. Lawrence River carp, or cor n oil (control). All received operant training to a final multiple (mult) 1 20-s, fixed interval (FI), 5-min extinction (EXT) schedule. Pressing rates of both exposed groups for drops of water averaged more than 1.5 times that of controls, especially toward the end of the 120-s interval. This overact ivity included bursts with short (less than or equal to 0.5 s) interrespons e times (IRTs), behavior characteristic of hyperactive boys and genetically hyperactive rats. The exposed groups also overreacted to the decreases in reinforcement density associated with transition to the final schedule. The results were interpreted in terms of the possible alterations in the anima ls' reinforcement mechanisms and the possible neurotoxic effects of PCB exp osure. (C) 2001 Elsevier Science B.V. All rights reserved.