The antidepressant mechanism of action of vagus nerve stimulation: Evidence from preclinical studies

Vagus nerve stimulation (VNS) is a proposed neuromodulatory treatment for medically refractory major depression. Although VNS is already used in clinical practice, the underlying mechanism of action remains unknown. The present review provides an overview of the preclinical VNS studies in view of two major hypotheses in depression research: the monoaminergic and the neural plasticity hypothesis of depression.