Anxiolytic Effects of Diazepam and Ethanol in Two Behavioral Models: Comparison of Males and Females

The present study compared the anxiolytic effects of the benzodiazepine agonist diazepam and ethanol in adult male and female rats. Varying doses of diazepam (1-3 mg/kg) or ethanol (0.5-2.0 g/kg) were tested using both the elevated plus maze and defensive prod-burying models. Two time points following ethanol administration (10 and 30 min) were tested in the plus maze. Sex differences were seen in some anxiety-related behaviors, with females showing greater open arm time and reduced burying behavior than males. Although this suggests females displayed less anxiety-like behavior than males, the differences in the plus maze were not observed in all testing situations. Both diazepam and ethanol dose-dependently increased open arm times in the plus maze and reduced burying behavior in the defensive prod-burying task. The parallel nature of the dose-response curves suggests that both diazepam and ethanol have similar anxiolytic effects in males and females. No sex differences were seen in the brain levels of diazepam-like activity or blood alcohol levels with these treatments. A greater corticosterone response was observed in females than males with these two behavioral tests, but neither diazepam nor ethanol decreased this response. These results suggest a dissociation between the anxiety-reducing influences of these compounds and the changes in stress-related endocrine responses.