Re-socialization reduces social isolation-induced high alcohol preference and anxiety via possibly restoring dopamine-rewarding effects in the rat striatum.

Social environmental factors frequently play an important role in early-life. It is reported that isolation increases vulnerability to develop alcohol use disorder. We investigated the effects of re-socialization on high alcohol preference and anxiety behaviors, induced by early-life social isolation (SI), and its possible underlying mechanism in male Wistar rats. On the 21st postnatal day, animals were either housed in groups of (CON) or isolated (SI-1) for the first stage (3 weeks). Afterwards, the SI-1 group were divided into two groups: re-socialization with socially housed rats (Re-SH) and isolation (SI-2) for a second stage (3 weeks). Both alcohol preference and behaviour tests were performed in these two stages. The ratio of dopamine content in striatum tissue was measured. The results showed that SI considerably induced the high alcohol preference and increased anxiety-like behaviors. However, during the 2nd stage, peer companionship significantly reduced the high alcohol preference and anxiety-like behaviors which were induced by early-life SI. Moreover, the striatal dopamine content was significantly enhanced by SI, but was evidently suppressed by re-socialization. Additionally, there was no statistical difference in body weight, anxiety-like behaviour, alcohol preference or dopamine content when the rats were only isolated during the SI-2 stage. It suggests that both the high alcohol preference and anxiety-like behaviors are able to be significantly reduced by re-socialization, which is possibly associated with regulating dopamine concentration.