INITIATION OF ETHANOL SELF-ADMINISTRATION BY THE SUCROSE-SUBSTITUTIONMETHOD WITH HAS AND LAS RATS

This study was performed to examine ethanol self-administration in rat s bred for different sensitivities to the sedative effects of alcohol [the Colorado High Alcohol Sensitive (HAS) and Low Alcohol Sensitive ( LAS) rats]. Four rats from each replicate line of the HAS and LAS rats (n = 16) were obtained from the University of Colorado, and initiatio n to self-administer ethanol by the sucrose-substitution procedure was attempted. Before the initiation procedure was conducted, home-cage e thanol intake and preference ratio did not differ between LAS and HAS rats. During the initiation procedure, the LAS rats came to self-admin ister 10% ethanol (v/v) at similar levels as outbred Wistar rats initi ated with the same procedure (similar to 0.4 g/kg/ session). The HAS r ats, however, failed to initiate (similar to 0.08 g/kg/session after c ompleting the sucrose-substitution procedure) and lever pressing was r educed even more in the HAS rats when the ethanol concentration presen ted was >10% (v/v). Three of the eight HAS rats stopped lever pressing completely when the ethanol concentration was raised to 15%. After in itiation, home-cage preference ratio differed significantly between th e LAS and HAS rats (LAS > HAS, p < 0.03). That the LAS rats did not co nsume greater amounts of ethanol compared with outbred Long-Evans or W istar rats is contrary to our hypothesis, based on recent human data s uggesting that a lower sensitivity to ethanol could result in increase d alcohol intake. The finding that the HAS rats could not be initiated , while selectively bred ethanol nonpreferring rats can, is also contr ary to our hypothesis. Further studies related to ethanol self-adminis tration with the HAS line could provide important information related to the genetics of alcohol nonacceptance.