Molecular basis of dendritic atrophy and activity in stress susceptibility.

Molecular and cellular adaptations in nucleus accumbens (NAc) medium spiny neurons (MSNs) underlie stress-induced depression-like behavior, but the molecular substrates mediating cellular plasticity and activity in MSN subtypes in stress susceptibility are poorly understood. We find the transcription factor early growth response 3 (EGR3) is increased in D1 receptor containing MSNs of mice susceptible to social defeat stress. Genetic reduction of Egr3 levels in D1-MSNs prevented depression-like outcomes in stress susceptible mice by preventing D1-MSN dendritic atrophy, reduced frequency of excitatory input and altered in vivo activity. Overall, we identify NAc neuronal-subtype molecular control of dendritic morphology and related functional adaptations, which underlie susceptibility to stress.