SEX-DIFFERENCES IN OPEN-FIELD BEHAVIOR IN RESPONSE TO THE BETA-CARBOLINE FG-7142 IN RATS

Sex differences in animal models of anxiety and depression that employ external stimuli have been previously reported. This study examined t he effect of gender on pharmacologically induced anxiety in rats coupl ed with novel handling, injection, and activity in an open-field test. The anxiogenic compound FG 7142 significantly decreased male open-fie ld exploratory at 5, 10, and 20 mg/kg, while rearing behavior was decr eased only at the 20 mg/kg dose. Female rats were more resistant to th e effects of FG 7142 on open-field exploratory behavior, decreasing op en-field activity, and rearing behavior only after the administration of a dose of 40 mg/kg. In addition, a significant sex difference was o bserved in the open-field activity of rats injected with the vehicle c ontrol. Male rats were less active but showed a similar level of reari ng behavior when compared to female rats. The greater sensitivity of m ale rats to the activity-suppressant effects of FG 7142 could explain the sex differences observed in several other animal models of anxiety and depression.