During the week prior to clonidine administration, baseline alcohol and water intakes during the daily 2-h alcohol-access period (1100–1300 hours) were calculated for each rat over 4 consecutive days and the rats were ranked in descending order in terms of average daily alcohol consumption. The rats were assigned to drug treatment groups in a manner that ensured that the groups did not differ in baseline alcohol intake prior to clonidine administration. Specifically, the top 5 alcohol drinkers were randomly assigned to the vehicle or one of four clonidine-treatment groups (10, 20, 40, or 80 µg clonidine/kg BW), followed by the next 5 highest alcohol drinkers likewise randomly assigned, etc.
