Ingestive behaviour of the pigeon: stereoselective influence of the opiate agonist levorphanol and its antagonism by naloxone.
Four experiments evaluated the effect of levorphanol on ingestive behaviour of different groups of non-deprived pigeons. In experiments 1 and 2, levorphanol and its (+)stereoisomer dextrorphan were administered at three doses (0.25, 1 and 2 mg). As compared with control values, levorphanol dose-dependently reduced food intake. This anorexia persisted for at least 5 h post-injection. A late hyperdipsia was also observed. These changes were stereoselective, suggesting that they followed the binding of levorphanol to opiate receptors. In experiments 3 and 4, the anorexic effect of 1 mg levorphanol, but not its hyperdipsic effect, was partly antagonized by the concomitant administration of either 0.25 mg or 1 mg naloxone. Given alone at the dose of 1 mg, naloxone slightly and transiently reduced food, but not water, intake. These results are discussed in terms of the endorphinergic regulation of ingestive behaviour in birds.
D000818:Animals; D010856:Columbidae; D004327:Drinking Behavior / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects*; D007981:Levorphanol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D013237:Stereoisomerism; D013997:Time Factors
D007981:Levorphanol; D009270:Naloxone