Multi-Target Antidepressant Action of Citrus medica L. var. sarcodactylis Swingle (Bergamot) Essential Oil: From PI3K/AKT-Driven Apoptosis Inhibition to BDNF/5-HT Signaling Activation

Depression is a worldwide affliction that seriously compromises social adaptation and physical well-being. Citrus medica L. var. sarcodactylis Swingle (also known as Bergamot) is a citrus plant in the Rutanceae family. Bergamot essential oil, a naturally derived product, has been reported to possess neuroprotective effects. The present study aimed to reveal the neuroprotective mechanisms of bergamot essential oil in PC12 cells, and compare its efficacy with that of its predominant constituent, D-limonene. To confirm the target of action, this study sought to use PI3K inhibitor LY294002 to validate the mechanism in modulating autophagy and apoptosis of bergamot essential oil. By constructing a corticosterone-induced PC12 cell model of depression in vitro , we observed that bergamot essential oil stimulated the PI3K/AKT/mTOR signaling cascade, reducing autophagy markers LC3-II and p62 approximately by 22 % and 37 % respectively, and decreasing apoptosis rates by 37 %. Bergamot essential oil intervention also upregulated 5-HT levels and played a positive role in the BDNF/TrkB pathway which associated with synaptic plasticity. D-limonene (56.6 % of bergamot essential oil) was demonstrated to be a key contributor to these mechanisms. It exhibited protective effects comparable to bergamot essential oil against autophagy and BDNF/5-HT signaling activation, however, bergamot essential oil showed better efficacy in alleviating apoptosis. This study provides in vitro mechanistic evidence supporting the potential application of bergamot essential oil in the treatment of depression.