Ontogenetic difference in ethanol reinforcing properties: the role of the opioid system.
Previous data indicate that ethanol intoxication (3 g/kg, intragastric) on postnatal day (PD) 7 and 8 increases ethanol acceptance, but on PD 10 and 11 generates an aversion in infant rats. We investigated the participation of the opioid system in these effects. Subcutaneous administration of naloxone (1 or 10 mg/kg) followed by ethanol intoxication on PD 7 and 8 prevented the increased ethanol intake effect observed in the younger pups, but when ethanol intoxication occurred on PD 10 and 11, naloxone treatment did not affect the aversion observed at this age. An aversion to ethanol was evidenced in the younger pups administered ethanol and naloxone, but only when exposed to ethanol odor during ethanol intoxication. Results indicate that the increased ethanol acceptance induced by ethanol intoxication in the younger pups is mediated by the opioid system, and that ethanol may also induce conditioned aversions at this early age.
Gabriela Chotro
M
M
Universidad del País Vasco - UPV/EHU, San Sebastian, Spain. g.chotro@ehu.es
Arias
Carlos
C
D000818:Animals; D000831:Animals, Newborn; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D018847:Opioid Peptides / Q000502:physiology*; D051381:Rats; D012054:Reinforcement, Psychology
D009292:Narcotic Antagonists; D018847:Opioid Peptides; D009270:Naloxone; D000431:Ethanol