SEX-DIFFERENCES IN SCHEDULE-INDUCED ALCOHOL-CONSUMPTION

Six female and five male Wistar rats obtained food by pressing a lever on a fixed-interval (FI) 60-s schedule in the presence of a sipper tube which allowed access to an alcohol solution. Systematic manipulation of the alcohol concentration revealed that male rats consumed higher alcohol concentrations (v/v) than female rats to obtain maximum alcohol intake (g ETOH/kg) during an experimental session. Males also reached higher blood alcohol levels (BALs) than females. Individual lick rates varied over a small range when the FI schedule parameter was manipulated (20 s and 180 s) during probe sessions. Very few licks were observed when all pellets were presented at the beginning of the session, during extinction, or during sessions in which only a few pellets were presented. Reduction of the solutions alcohol concentration to half the maximum concentration or presentation of distilled water resulted in increased lick rates at most values of the FI schedule in four male subjects, but not in female subjects. Alcohol intake during sessions in which half the maximum alcohol concentration. The lick rate data in conjunction with those on alcohol intake suggest that male rats, but not female rats, maintained blood alcohol concentrations at levels which they have also reached during sessions in which the maximum alcohol concentration was available from the sipper tube.