Abstract
Disrupted-in-schizophrenia-1 (DISC1) is associated with mental disorders, including major depression. We previously showed that DISC1-Q31L mutant mice have depression-like behaviors and can therefore be used to study neurobiological mechanisms of depression and antidepressant (AD) medication action. First, we found reduced levels of dopamine, serotonin and norepinephrine in the nucleus accumbens (NAC) of DISC1-Q31L mutants. Next, we assessed social-conditioned place preference as a reward-dependent task and the capacity of distinct ADs to correct impaired social behavior in DISC1-Q31L mice. Bupropion, but not fluoxetine or desipramine, was able to correct deficient social facilitation, social reward, and social novelty in DISC1-Q31L mutants, whereas all three ADs were able to improve social motivation and behavioral despair in DISC1-Q31L mutants. Furthermore, we sought to correlate social anhedonia with molecular and cellular features including dendritic spine density, β-arrestin-1,2, and cAMP-response-element-binding protein (CREB) in the NAC as biomarkers related to depression and the DISC1 pathway. DISC1-Q31L mutants showed reduced levels of β-arrestin-1,2, CREB, and spine density in the NAC, further supporting the construct validity of the genetic model. Bupropion induced the greatest effect on CREB in DISC1-Q31L mutants, whereas all studied ADs corrected the reduced levels of β-arrestin-1,2 and modestly ameliorated deficient spine density in this brain region. Overall, we find neurobiological changes accompanying social anhedonia in the NAC of DISC1-Q31L mutant mice, consistent with a role for DISC1 in regulating social reward as an endophenotype of depression.