In adolescence, female rats are more sensitive to the anxiolytic effect ofnicotine than are male rats

Anxiety may play an important role in the onset of smoking, particularly in young girls. This study examined whether there were sex differences in the effects of nicotine on anxiety in adolescent rats and whether social isola tion modified these effects. Male and female adolescent rats were housed in groups of the same sex or in social isolation for seven days prior to test ing in the social interaction test Of anxiety. Nicotine increased social in teraction in both males and females, and because there was no concomitant c hange in locomotor activity, this indicated anxiolytic effects. However, th ere was a 5-fold sex difference in the lowest dose required to enhance soci al interaction, with an anxiolytic effect in females at 0.05mg/kg, but in m ales only at 0.25mg/kg. Furthermore, in males the anxiolytic effect was see n only in socially isolated animals, whereas in the females it was present in both housing conditions. The depressant effect of nicotine on locomotor activity also depended on both the sex of the animal and on their housing c onditions, with greater effects in singly housed animals and in males. This sex difference in sensitivity to nicotine's anxiolytic effects suggests th ere may be sex differences in the factors initiating and maintaining teenag e smoking.