Abstract
The purpose of this study was to investigate the antidepressant mechanism of GEN (geniposide) on depression mice induced by LPS. The mice were intragastrically treated with GEN (10 mg/kg/d or 40 mg/kg/d) or ibrutinib for continuous 7 days prior to LPS injection. The anxiety- and depression-like behaviors of mice were assessed via behavioral tests (sucrose preference test (SPT), tail suspension test (TST), forced swimming test (FST), and open-field test (OFT)). Microglial BV2 cells were treated with GEN or/and ibrutinib and stimulated with LPS. The productions of pro-inflammatory cytokines IL-6 and TNF-α in hippocampus, serum, and supernatant were detected by ELISA. The correlative proteins BTK, p-BTK, JAK2, p-JAK2, STAT1, p-STAT1, BDNF, TrkB, and p-TrkB were assessed through western blot. As a result, GEN ameliorated the anxiety- and depression-like behaviors of mice in behavioral tests. GEN treatment also regulated microglia polarization towards anti-inflammatory phenotype M2 and inhibited the production of pro-inflammatory cytokines IL-6 and TNF-α. In addition, with the application of ibrutinib, the selective inhibitor of BTK, it was proclaimed that the administration of GEN restrained the activation of JAK2/STAT1 pathway via attenuating the hyperphosphorylation of BTK both in mice and BV2 cells. Furthermore, it was also found that GEN activated BDNF/TrkB neuroprotective signaling pathway through the reduction of BTK phosphorylation. From the overall results, we suggested that GEN exerted a beneficial effect on LPS-induced depression in mice possibly through the modulation of BTK/JAK2/STAT1 signaling.