Effects of the 5-HT1A agonist 8-OH-DPAT on operant feeding in pigs.

The effect of intravenous (i.v.) injection of 8-OH-DPAT on operant food intake in pigs has been examined in animals with food available ad lib and in pigs feeding after 4 h deprivation of food. Operant methods were used to ascertain whether any increases in food intake were due to increased motivation to feed rather than stereotypic chewing movements. In nondeprived animals i.v. injection of 8-OH-DPAT at doses of 10, 30, and 50 micrograms/kg significantly increased food intake in the 45 min following injection. In pigs feeding after 4 h deprivation, i.v. injection of 8-OH-DPAT at doses of 30 and 50 micrograms/kg, given 5 min before feeding commenced, had no effect on food intake.