Presentation of an ethanol-paired stimulus complex alters response patterns during extinction

It has been hypothesized that environmental stimuli previously paired with ethanol consumption play a role in excessive ethanol intake. This study exa mined the ability of orally self-administered ethanol to establish a tone-l ight stimulus complex as a conditioned reinforcer (CSR). Male Long-Evans ra ts were trained to orally self-administer 10% ethanol (10E) using the sucro se-substitution procedure. During training, a tone-light stimulus complex w as paired with ethanol presentation in a stimulus complex paired (SC paired ) group but not in a control group. Responding during extinction in the pre sence and absence of the stimulus complex was then examined. Following the initiation of ethanol self-administration, 10E maintained greater respondin g in the SC paired group compared to the control group. When the stimulus c omplex was presented contingent on responding during extinction, the rate o f extinction was slightly attenuated in the SC-paired group but not in the control group. The altered rate of extinction in the SC-paired group was ch aracterized by: 1) a slight decrease in total session responding over succe ssive days of extinction and 2) a transient attenuation of extinction burst response rate during the first extinction session. These data suggest the stimulus complex could function as a weak CSR, but overall its ability to m aintain lever pressing was minimal. (C) 1998 Elsevier Science Inc.