Downregulation of hippocampal SIRT6 activates AKT/CRMP2 signaling and ameliorates chronic stress-induced depression-like behavior in mice

Sirtuin 6 (SIRT6) has been reported to play a key role in cognitive function and mood regulation, yet its role in mood disorders is not completely understood. Here, we confirmed that knockdown of hippocampal SIRT6 alleviated depression-like behaviors induced by chronic unpredictable stress (CUS) in mice. Our in vitro data showed that SIRT6 negatively regulated protein kinase B (Akt) signaling by deacetylating histone 3 at Lys9 and Lys56. Knockdown of SIRT6 significantly increased Akt phosphorylation activity, while decreased collapsin response mediator protein 2 (CRMP2) phosphorylation activity. Furthermore, pharmacologic inhibition of SIRT6 by ferulic acid (FA) (40 or 80 mg· kg^-1 per day, i.g.) could activate Akt/CRMP2 pathway in vitro, which has been proved to exert an antidepressant-like effect on CUS-induced depressive models. In conclusion, our study suggested that hippocampal SIRT6 contributes to the performance of depression-like behaviors by suppressing Akt/CRMP2 signaling, and FA ameliorates CUS-induced depression-like behaviors in mice as a potential pharmacologic inhibitor of SIRT6.