Operant infantile self-administration of ethanol: role of prior exposure to the drug and effects upon adolescent ethanol intake.

PONCE, L.F.; PAUTASSI, R.M.; SPEAR, N.E.; MOLINA, J.C.

Chicago, Illinois, EEUU

Congreso; 2007 Annual Meeting of the Research Society on Alcoholism.; 2007

Research Society on Alcoholism

Aversive as well as appetitive attributes of ethanol (EtOH) have been observed in young rats when utilizing classical conditioning procedures. The development of operant-based tasks is desirable to better understand early patterns of self-administration of the drug and latter consequences upon ethanol affi nity. The main goal of the present study was to assess the effects of pre-exposure to ethanol upon later self-administration patterns of the drug during infancy using an operant conditioning task. The effect of these early experiences upon adolescent’s affi nity for ethanol ingestion was also evaluated. Thirteen-days-old pups (PD13) were pre-exposed to intraoral infusions of either ethanol (7.5% v/v) or water. Following this pre-exposure phase, daily operant training sessions were conducted (PDs 14–17). Nosepoking was reinforced with either intraoral pulses of water or ethanol (3.75% v/v). Infants pre-exposed to ethanol and later reinforced with the drug exhibited signifi cantly higher levels of nose poking when compared with the remaining groups. Blood ethanol concentrations in ethanol reinforced pups (PD 17) ranged between 31–49 mg%. Experiment II was conducted using a similar operant training procedure as the one described for Experiment 1. Infants had been pre-exposed to 7.5% v/v ethanol and later trained with water, 3.75% or 7.5% v/v EtOH (PDs 14–17). During periadolescence, they were evaluated in a free-choice ethanol intake test (duration: 2 hrs/day). Rats had free access to water and a given ethanol solution (3, 4, 5 or 6% v/v on PDs 30, 31, 32 and 33; respectively). Rats reinforced with ethanol during infancy exhibited higher levels of ethanol intake when compared with water reinforced animals. Taken together, these results indicate that EtOH pre-exposure during infancy facilitates subsequent self-administration of the drug when employing an operant conditioning procedure. In turn, ethanol reinforcement during infancy promotes heightened affi nity for ethanol ingestion during periadolescence. Familiarization with ethanol’s orosensory properties, development of tolerance to the drug’s aversive properties and/or sensitization to ethanol’s positive reinforcing represent potential factors that can help explain the results under consideration.