Sex differences in pattern of drinking.

Drinking patterns of male and female Long-Evans rats were compared during a 15-day drinking period. All animals were tested for preference for alcohol for 24 h during which food, water, and beer containing 5% ethanol were freely available. Animals drinking 50 ml or more of beer were chosen for the experiments. On days 1-5, animals were offered food, water, and beer containing 5% ethanol (v/v). On days 6-15, the concentration of ethanol in the beer was doubled to 10% (v/v). Preference ratios (beer/total fluid) were higher for females than males, and females consumed more grams of alcohol per unit of body weight. When alcohol concentration was doubled, females increased alcohol intake (g/kg), while males tended to titrate alcohol intake to levels consumed at 5% concentration. Female patterns of drinking differed from male patterns of drinking.