WATER DEPRIVATION-INDUCED ORAL SELF-ADMINISTRATION OF COCAINE IN THE LEWIS RAT - EVIDENCE FOR LOCOMOTOR EFFECTS BUT NOT REINFORCEMENT

Oral cocaine self-administration was studied in water-deprived Lewis r ats. Liquid was available to rats only during daily 90-min sessions, i n chambers equipped with spouts that delivered precise volumes of liqu id following completion of lever-press responses. Blocks of training a nd testing sessions were alternately carried out during which increasi ng cocaine concentrations were presented: 0.0, 0.0125, 0.025, 0.05, 0. 1, 0.2, 0.282, and 0.4 mg/ml. Although high cocaine intakes (23.3-33.0 mg/kg) were obtained, neither avoidance nor preference for cocaine de veloped. Subsequently, fixed-ratio size was increased, and then distin ctive stimulus lights were correlated with each liquid. One rat showed a preference for water following these changes, but two rats continue d to show no preference. To determine if the amounts of cocaine self-a dministered had behavioral effects, locomotor activity tests were run immediately following self-administration sessions. Locomotor activity was substantially higher following cocaine self-administration than f ollowing water self-administration. These results demonstrate that the cocaine intakes reached under the present conditions did produce loco motor, but not reinforcing, effects.