Comparison of alcohol-preferring and nonpreferring selectively bred rat lines. I. Ethanol initiation and limited access operant self-administration

Several lines of alcohol-preferring and alcohol-nonpreferring rats have bee n developed using selective breeding based on 24-hr homecage ethanol consum ption, However, it remains unclear if the selection based on two-bottle cho ice resulted in similar ethanol self-administration when measured using an operant procedure, In this paper, we compare our previous work using alcoho l-accepting (AA) and alcohol-nonaccepting (ANA) rats with data obtained usi ng the identical procedures in the (P) and (NP) rat lines, and both replica te lines of the high alcohol drinking (HAD1 and HAD2) and low alcohol drink ing (LAD1 and LAD2) lines. All rats from each line were initiated to self-a dminister 10% ethanol using the sucrose fading procedure. After initiation, increasing concentrations of ethanol up to 30% ethanol were tested, The re sults indicated that only in the LAD1 and LAD2 lines was ethanol presentati on not able to maintain lever pressing after initiation. Compared with the AA line, the P, HAD1, HAD2, and NP lines all self-administered more ethanol in the operant paradigm after initiation. The ANA line self-administered l ess ethanol than the AA line, but more than the LAD lines, Correlational an alysis of homecage consumption with operant ethanol self-administration sug gested that similar to 62% of the genetic variance in operant self-administ ration resulted from genes selected for the homecage drinking. At the same time, it was clear that there were genetic influences on operant self-admin istration that were not selected for by homecage ethanol drinking.