The antidepressant effect of nucleus accumbens deep brain stimulation is mediated by parvalbumin-positive interneurons in the dorsal dentate gyrus.

The nucleus accumbens (NAc) is a crucial region in the reward circuit and is related to anhedonia, the pivotal symptom of major depression disorder (MDD). Deep brain stimulation (DBS) of NAc has been identified as an effective treatment for severe refractory major depression; however, the underlying mechanism of NAc-DBS in MDD treatment remains elusive. Using the chronic unpredictable mild stress (CUMS) mouse model, we found NAc-DBS rescued depression-like behaviors, and reversed high gamma oscillation reduction and neurogenesis impairment in the dorsal dentate gyrus. Inactivation of parvalbumin (PV)-positive interneurons (PVI) in the dorsal DG led to depression-like behavior and decreased adult neurogenesis. Further investigation elucidated the VTA-DG GABAergic projection and CA1-NAc projection might jointly participate in NAc-DBS therapeutic mechanism. Disinhibition of the VTA-DG GABAergic projection had an antidepressant effect, and inhibition of the CA1-NAc projection reduced the antidepressant effect of DBS-NAc. Moreover, disinhibiting the VTA-DG GABAergic projection or activating the CA1-NAc projection could increase PVI activity in the dorsal DG. These results showed PVI in the dorsal DG as an essential target in depression and NAc-DBS antidepressant mechanisms.