abstract
- The report examines the temporal sequence of yawns induced by apomorphine and whether the opiate antagonist, naloxone, affects it. Before administering apomorphine (0.075 mg/kg) or saline, rats (n = 8) were pretreated with naloxone (1 mg/kg) or saline. Each subject received all 4 possible treatments (saline-saline, saline-apomorphine, naloxone-saline, and naloxone-apomorphine) in random order. Results indicate that yawning induced by apomorphine seems to come in fits; that is, there is a series of yawns spaced closely together and followed by a period of quiescence before the start of another cluster of yawns. Naloxone reduced the number of apomorphine-induced yawns, and the occurrence of very short inter-yawn intervals. It is suggested that the timing of yawns may provide useful information regarding some pathologies and that opiates may potentiate the action of dopaminergic systems.