Operant conditioning with a stimulus discrimination: An alternative method for evaluating alcohol reinforcement in preweaning rats

Ethanol exposure at early ontogeny promotes further predisposition to consume the drug. Operant conditioning allows motivational alcohol properties to be assessed. To date, the operant conditioning approach used during infancy consisted in paired subjects being trained to learn an operant response, using simultaneously a yoked partner, which received reinforcer solution as a result of a paired animal instrumental response (OYS). In our study, we attempted to evaluate ethanol reinforcing effects during PDs 15–18 in an operant conditioning schedule with a stimulus discrimination procedure (OSD), as an alternative control learning. This new proposal includes a single subject, who has to choose between an S+ nose-poke hole, which delivers the reinforcer into the mouth, or an S- nose-poke hole with no reinforcement effect. The OSD results seemed to be more reliable than those obtained using the OYS procedure, since some data appeared to be more robust when using a yoked nose-poke hole than when employing a yoked subject, such as in control learning. Consequently, OSD has the following advantages compared to the OYS procedure: a) the operant response learned is controlled by the overall behavior of the same subject, resulting in a relatively clearer data; b) a yoked animal is not necessary, thereby reducing the number of rats used in the operant conditioning procedure. A novel technique of operant conditioning adapted to infancy was developed by training animals to emit a particular response to gain access to alcohol solution as a reinforcer. •Operant conditioning with stimulus discrimination in infant rats.•Alcohol self-administration evaluated by a stimulus discriminative procedure.•Alcohol reinforcement, infancy and operant discrimination of stimulus.