Effects of the dopamine D2 agonists lisuride and CQ 32-084 on rat feeding behaviour

The influence on rat-feeding behaviour of lisuride and CQ 32-084, agonists at dopamine D2 receptors, was examined using two procedures. In a first series of experiments, the apparatus was an X-maze baited with food pellets where individual fasted rats were observed for 5 min. A number of parameters were recorded: latency to tasting and feeding, interval between tasting and feeding, total feeding time, and total grooming time. Lisuride (0.05 and 0.1 mg/kg) and CQ 32-084 (0.05 and 0.5 mg/kg) behaved as stimulants of eating; lisuride (0.4 mg/kg) inhibited the phenomenon. Both drugs always antagonized grooming. Subsequently, when food intake was determined in the home cages of fasted animals lisuride reduced feeding at all doses during the first hour after treatment, while CQ 32-084 had no effect. The data show that the two compounds display different activity on ingestive behaviour according to the dose and experimental model used. Discussion centres on the possible dependence of feeding enhancement in the X-maze on the anxiolytic activity exerted by low D2 autoreceptorial doses.