Insulin, 2-deoxy-D-glucose, and food deprivation as discriminative stimuli in rats

Using a two-lever drug discrimination procedure, two groups of four rats each were trained to discriminate the stimulus effects of 1.0 U/kg insulin or 125 mg/kg 2-deoxy-D-glucose (2-DG) from saline. A third group was trained to discriminate food deprivation produced by feeding 23 h prior to sessions from satiation produced by feeding 2 h prior to sessions. Differential responding was a direct function of dose or deprivation level in each group. Rats trained to discriminate insulin responded as if they had received insulin when they received 2-DG and vice versa. Insulin and 2-DG produced deprivation-appropriate responding in two of four rats trained to discriminate food deprivation. Low insulin and 2-DG doses produced drug-appropriate responding in rats deprived 47 h, but not in rats deprived 23 h. Blood glucose level was altered by the training doses of insulin and 2-DG, but not by 23-h deprivation. These results indicate that operations that induce feeding produce discriminable stimuli, and that these effects overlap or interact. Thus, drug discrimination procedures can be useful in the analysis of ingestive behavior.