Development of a test battery for social behavior and assessing a rat model for bipolar disorder

To develop new therapeutic options for the treatment of bipolar disorder, animal models are a valuable tool to understand underlying changes in neurobiology. By manipulating the prefrontal dopamine D1 receptor our group was able to induce mania- as well as depressive-like behavior in rats. As social behavior is largely affected in bipolar disorder, we aim to phenotype our model in this respect. Therefore, a test battery including social hierarchy in three different tests (social dominance tube test, food competition test, urine scent mark test), sexual motivation and sexual behavior in adult rats of both sexes was developed. Results showed that the three hierarchy test did not correlate and presented different results. However, the social dominance tube test seemed to be the most stable and appropriate test for hierarchy. A sex-specific correlation was visible between hierarchy and sexual activity. There were correlations between sexual activity and sexual motivation, and between hierarchy and sexual motivation in males, while there were no correlations for females. The sexual incentive motivation paradigm highly depended on females’ receptivity. Males preferred the receptive female while receptive females preferred the male. With non-receptive females no preference for sex (of either sex) was observed highlighting the need for precise hormone treatment. In a next step, the established tests will now be used in the model for bipolar disorder. Extending our observations on impairments in social behavior and for the first time applying the model in females will increase face and construct validity of the model.