title: Timing of yawns induced by a small dose of apomorphine and its alteration by naloxone.
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.
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects*; D012119:Respiration / Q000187:drug effects
chemical_list: D009270:Naloxone; D001058:Apomorphine