Social anhedonia as a Disrupted-in-Schizophrenia 1-dependent phenotype.

Deficits in social interaction or social cognition are key phenotypes in a variety of chronic mental diseases, yet, their modeling and molecular dissection are only in their infancy. The Disrupted-in-Schizophrenia 1 (DISC1) signaling pathway is considered to play a role in different psychiatric disorders such as schizophrenia, depression, and biopolar disorders. DISC1 is involved in regulating the dopaminergic neurotransmission in, among others, the mesolimbic reward system. A transgenic rat line tgDISC1 has been introduced as a model system to study behavioral phenotypes associated with abnormal DISC1 signaling pathways. Here, we evaluated the impact of impaired DISC1 signaling on social (social interaction) and non-social (sucrose) reward preferences in the tgDISC1 animal model. In a plus-maze setting, rats chose between the opportunity for social interaction with an unfamiliar juvenile conspecific (social reward) or drinking sweet solutions with variable sucrose concentrations (non-social reward). tgDISC1 rats differed from wild-type rats in their social, but not in their non-social reward preferences. Specifically, DISC1 rats showed a lower interest in interaction with the juvenile conspecific, but did not differ from wild-type rats in their preference for higher sucrose concentrations. These results suggest that disruptions of the DISC1 signaling pathway that is associated with altered dopamine transmission in the brain result in selective deficits in social motivation reminiscent of phenotypes seen in neuropsychiatric illness.