Background: Major depression and anxiety disorder are significant causes of disability and socio-economic burden. Despite the prevalence and considerable impact of these affective disorders, their pathophysiology remains elusive. Thus, there is an urgent need to develop novel therapeutics for these conditions. We evaluated the role of SIRT1 in regulating dysfunctional processes of reward by using chronic social defeat stress (CSDS) to induce depression- and anxiety-like behaviors. CSDS induces physiological and behavioral changes that recapitulate depression-like symptomatology and alters gene expression programs in the nucleus accumbens, yet cell type-specific changes in this critical structure remain largely unknown.
Methods: We examined transcriptional profiles of D1-MSNs lacking deacetylase activity of SIRT1 by RNA sequencing (RNA-Seq) in a cell-type specific manner using the RiboTag line of mice. We analyzed differentially expressed genes using gene ontology tools including SynGO and EnrichR, and further demonstrated functional changes in D1-MSN specific SIRT1-KO mice using electrophysiological and behavioral measurements.
Results: RNAseq revealed altered transcriptional profiles of D1-MSNs lacking functional SIRT1 and showed specific changes in synaptic genes including glutamatergic and GABAergic receptors in D1-MSNs. These molecular changes may be associated with decreased excitatory and increased inhibitory neural activity in Sirt1-KO D1-MSNs, accompanied by morphological changes. Moreover, the D1-MSN-specific Sirt1-KO mice exhibited pro-resilient changes in anxiety- and depression-like behaviors.
Conclusions: SIRT1 coordinates excitatory and inhibitory synaptic genes to regulate GABAergic output tone of D1-MSNs. These findings reveal a novel signaling pathway that has the potential for the development of innovative treatments for affective disorders.
Keywords: Anxiety; Depression; SIRT1; cell-type specificity; nucleus accumbens; translatome.
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