THE EFFECTS OF WAY-100135 AND 8-HYDROXY-2-(DI-N-PROPYLAMINO)TETRALIN ON FEEDING IN THE RAT

We have examined the effects of the selective 5-HT1A receptor antagonist, WAY-100135, on feeding and on 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT)-induced hyperphagia in rats. Given alone, WAY-100135 (1-10 mg/kg s.c.) did not affect the food intake of fasted or satiated rats; however, in free feeding rats, WAY-100135 (3 mg/kg s.c.) significantly attenuated 8-OH-DPAT-induced hyperphagia (0.1 mg/kg s.c.). Using a satiety sequence analysis of feeding behaviour, WAY-100135 (1 mg/kg s.c.) did not affect behaviour per se, but significantly antagonised the increased incidence of feeding, but not the decrease in observations of grooming following 8-OH-DPAT (0.1 mg/kg s.c.). These data provide the first demonstration of the antagonism, by a selective 5-HT1A receptor antagonist, of 8-OH-DPAT-induced feeding; an effect mediated via the somatodendritic 5-HT1A autoreceptor. These results also suggest that 5-HT1A receptor antagonists may have no intrinsic effect on food intake or feeding behaviour.