Effects of the 5-HT1A receptor agonist 8-OH-DPAT on operant food intake infood-deprived pigs

The effects of the 5-HT1A agonist 8-hydroxy-2 (di-n-propylamino)tetralin (8 -OH-DPAT) were investigated on operant food intake in food-deprived pigs. I n Experiment 1, 8-OH-DPAT (5-20 mu g/kg) administered intravenously (i.v.) 15 min prior to the occurrence of feeding produced a dose-related decrease in operant food intake in pigs that had been fasted overnight. The effects were mainly apparent during the first 30 min after the start of the feeding period. In Experiment 2, 8-OH-DPAT (25 and 50 mu g/kg, i.v.) administered 60 min prior to the ocurrence of feeding in pigs that were fasted overnight also produced significant decreases in food intake. The effects were, main ly apparent during the first 30-40 min after the start of the feeding perio d. In Experiment 3, 8-OH-DPAT (20 mu g/kg, i.v.) significantly increased op erant feeding in satiated pigs during the first 30 min after administration . These results show that 8-OH-DPAT has complex effects on feeding behaviou r in pigs, increasing operant food intake in satiated pigs, while producing a reduction in food intake in food-deprived animals. (C) 1999 Elsevier Sci ence Inc.