Study on Antidepressant Effect and Mechanism of Crocin Mediated by the mTOR Signaling Pathway

Crocin is a monomer of Chinese traditional herbs extracted from saffron, relieving depression-like behavior. However, its underlying mechanism of action remains unclear. Herein, we explored whether crocin's antidepressant effect depended on the mammalian target of the rapamycin (mTOR) signaling pathway. The model of PC12 cells injury was established by corticosterone, the changes in cell survival rate were tested by the CCK-8 method, and the changes in cellular morphology were observed under a fluorescence microscope. The depression model was established by chronic unpredictable mild stress (CUMS), and its antidepressant effect was estimated by open field test (OFT), forced swimming test (FST), and tail suspension test (TST). Western blot was used to monitor the protein expression. The results showed that crocin could effectively improve cell survival rate and cellular synaptic growth, alleviate the depressive behavior of CUMS mice, and promote the expression of BDNF, P-mTOR, P-ERK, and PSD95. However, when rapamycin was pretreated, the antidepressant effects of crocin were inhibited. In summary, crocin plays a significant antidepressant effect. After pretreatment with rapamycin, the anti-depression effect of crocin was significantly inhibited. It is suggested that the mechanism of the anti-depression effect of crocin may be related to the mTOR signaling pathway.