Caffeine-induced taste aversions in Lewis and Fischer rat strains: Differential sensitivity to the aversive effects of drugs

Abstract

Lewis (LEW) and Fischer 344 (F344) rat strains have been reported to differ in the aversive effects induced by a number of drugs. The present studies extended this previous work and examined the ability of caffeine to induce taste aversions in the two strains. Specifically, LEW and F344 rats were given access to saccharin and injected with varying doses of caffeine (0, 0.32, 1.0 and 3.2mg/kg—Experiment 1; 0, 10, 18 and 32mg/kg—Experiment 2). Additionally, the effects of caffeine on locomotor activity were examined in Experiment 2. At low doses (Experiment 1), caffeine failed to induce taste aversions in either strain. At higher doses (Experiment 2), aversions were induced that were strain dependent. Specifically, caffeine induced taste aversions in both strains at 32mg/kg, while 18mg/kg caffeine was effective in inducing aversions only in the LEW strain. Caffeine increased activity in both strains with no strain difference. This demonstration adds to the growing list of drugs on which the LEW and F344 strains differ in relation to their affective properties. Given that drug use and abuse are a function of the balance of the rewarding and aversive effects of drugs, understanding such strain differences may provide insight into the biological (and genetic) factors impacting abuse vulnerability.