Social isolation after a single defeat reduces striatal dopamine transporter binding in rats

A single social defeat in male rats has long lasting physiological and behavioural consequences, which are similar to those seen in depressive patients. In addition, the housing conditions after social defeat appear to be crucial for the development of depression-like symptoms. Because the dopaminergic system is thought to be altered in depressive illness, we investigated the impact of individual and group housing on the temporal development of changes of dopamine transporter (DAT) binding in male rats after a single social defeat. The number of striatal DAT binding sites was reduced in animals that remained isolated after being defeated. The isolation length after social defeat amplified this effect, indicating a temporal development of the changes on the striatal DAT. In animals which returned to the familiar group after social defeat the density of striatal DAT binding sites was not affected. We conclude that social isolation after a single defeat reduces the number of DAT binding sites. In contrast, a familiar environment after a single social defeat appears to prevent the stress-induced alterations on the dopaminergic system. This finding suggests that housing conditions are critical when investigating the central nervous effects of social defeat in male rats.