Opioid system blockade inhibits operant behaviors in an infantile model of ethanol self-administration task

MIRANDA MORALES RS; MOLINA JC; SPEAR NE; ABATE P

Congreso; IIRCN, Second Joint Meeting of the Argentine Society for Neurosciences (SAN) and the Argentine Workshop in Neurosciences (TAN) Huerta Grande, October 6-10, 2010.; 2010

ARGENTINE SOCIETY FOR NEUROSCIENCE

This study analyzed ethanol operant self-administration, in infants. Involvement of opioid system in the acquisition or expression of this experience was inquired. Infant rats (PDs14-17) have to display a target behavior (nose-poke) to gain access to 5% sucrose, 3.75% ethanol or water. On PD18 an extinction session was included. Sucrose and ethanol promoted higher levels of responses than water. During extinction, seeking behavior was only observed in pups reinforced with sucrose or ethanol. In a second study, only ethanol was used as reinforcer. At PDs16-17, 6-hr before training, pups were re-exposed to ethanol under opioid antagonism effects (naloxone, 1 mg/kg). During training, pups pre-exposed to ethanol under naloxone effects, failed to increase nose-poking responses to ethanol. Re-exposure conditions had no effects at extinction. In a third experiment a re-exposure trial was included at PD18. Prior extinction, pups were injected with naloxone and re-exposed to ethanol. The main result was a reduction of seeking behavior during extinction, in pups re-exposed to the drug -under naloxone effects- at PDs16, 17 and 18. These results indicate that opioid system seems to being modulating ethanol reinforcing effects, in terms of both appetitive and consummatory behaviors.