Effects of chronic low-dose acrylamide exposure on progressive ratio performance in adolescent rats

Abstract

Acrylamide (ACR) is a neurotoxicant known to produce peripheral neuropathy in rats and humans, but little is known of its potential for producing cognitive or motivational alterations. Chronic exposure to low doses of ACR as a food contaminant is known to occur widely in humans. This research evaluated the effects of daily ACR exposure on food-motivated behavior, with exposures beginning prenatally on gestation day 6 and continuing through approximately postnatal day (PND) 85. Plug-positive Fischer 344 dams (9–10 per dose) were gavaged daily with 0, 0.1, 0.3, 1.0 or 5.0 mg/kg/day ACR. On PNDs 1–22, pups were gavaged with the same dose their dam had received. On PND 22, pups were weaned and pair-housed with a same-sex littermate and ACR exposure continued at 0, 1, 3, 10 and 50 ppm via drinking water. One male and one female pup per litter were tested in an operant chamber under a progressive ratio (PR) schedule of food reinforcement from approximately 6 to 12 weeks of age. Results over 6 weeks of testing indicated a significant treatment effect of ACR on number of reinforcers earned, with Tukey HSD post hoc tests revealing significantly fewer reinforcers earned in the 5.0 mg/kg/day dose group than in controls. A significant effect of ACR on response rate was also observed, with the Tukey HSD post hoc tests revealing a significantly lower response rate in the 5.0 mg/kg/day group than in controls. No effects of ACR were observed on post-reinforcement pause. These data suggest that daily ACR exposure at 5.0 mg/kg/day can produce measurable decrements on aspects of food-motivated behavior.