Naloxone attenuation of ethanol-reinforced operant responding in infant rats in a re-exposure paradigm

ROBERTO SEBASTIAN MIRANDA MORALES; JUAN CARLOS MOLINA; NORMAN E SPEAR; PAULA ABATE

PSYCHOPHARMACOLOGY

SPRINGER

Año: 2012 vol. 219 p. 235 - 246

0033-3158

Rationale: Early ethanol exposure promotes ethanol reinforcement, mediated perhaps by ethanol?s motivational effects. The opioid system mediates ethanol reinforcement, at least in part. Objectives: Modulation of consummatory and seeking behaviors by the opioid system was tested in terms of ethanol or sucrose operant self-administration. Methods: Wistar-derived infant rats were tested in an operant conditioning task. (1) Infants were trained on postnatal days (PDs) 14?17 to obtain 5% sucrose and 3.75% ethanol or water, and evaluated in an extinction session at PD 18. (2) Ethanol (3.75%) was used as reinforcer. At PDs 16?17, 6 h before operant task, pups were re-exposed to ethanol after naloxone injection (0 or 1 mg/kg). (3) Sucrose (5%) acted as reinforcer. Pups were re-exposed to sucrose after naloxone injection. (4) A PD 18 re-exposure trial in which pups were injected with naloxone and re-exposed to ethanol was added.