The protective effect of 5-O-methylvisammioside on LPS-induced depression in mice by inhibiting the over activation of BV-2 microglia through Nf-κB/IκB-α pathway

Background: 5-O-methylvisammioside (MeV), also known as 4'-O-beta-D glucosyl-5-O-methylvisamminol, is a conventional marker compound for quality control of roots of Saposhnikovia diviaricata (Radix Saposhnikoviae), which exhibits anti-inflammatory and neuroprotective activities. Purpose: According to the activity of MeV, we speculated that MeV may have antidepressant effect on LPS induced depression, and further explored its mechanism. Study Design: First, to explore the effect and mechanism of MeV on LPS-induced depression in mice, and then to further explore the effect and mechanism of MeV on LPS-activated BV-2 microglia. Methods: By the OFT, EPM, TST and FST behavioral tests, to explore the effect of MeV pretreatment on the behavior of LPS-induced depression mice. ELISA and Griess method were used to detect the changes of the serum TNF-alpha and IL-6 levels, the hippocampus SOD and MDA levels, and the NO, SOD, MDA, TNF-alpha and IL-6 levels in the culture medium of LPS-stimulated BV-2 microglia. Western blot was used to analyze the protein expression in the Nf-kappa B/I kappa B-alpha and BDNF/TrkB pathway in the hippocampus of mice and BV-2 microglia. Results: MeV (4 mg/kg, i.p.) pretreatment significantly improves the activity and exploration ability of LPS-induced depression mice, and reduces the immobility time. MeV inhibited the production of pro-inflammatory cytokines in the serum of mice induced by LPS, such as IL-6 and TNF-alpha. MeV also increased the levels of SOD and reduces the expression of MDA in the hippocampus, thus promoting the alleviation of depressive symptoms in mice. Western blotting analysis showed that the antidepressant activity of MeV was related to the decrease of Nf-kappa B nuclear transport, the inhibition of I kappa B-alpha phosphorylation, and the increase of BDNF and TrkB expression. MeV (40 mu M) significantly reduced the contents of NO, MDA, TNF-alpha and IL-6 in the culture medium of LPS-stimulated BV-2 microglia, and increased the content of SOD. Conclusion: MeV can regulate the neurotrophic factors in the mouse brain, reduce the content of inflammatory factors by the Nf-kappa B/I kappa B-alpha pathway, improve oxidative stress, and inhibit the excessive activation of LPS-stimulated BV-2 microglia. It effectively reversed the depression-like behAavior induced by LPS in mice.