Research on the Antidepressant Mechanisms of Polygonati sibiricum Polysaccharides Based on Microglia Cell Polarization

Polygonum sibiricum is a traditional Chinese food and medicine homologues with multiple active ingredients and extensive bioactive effects. Polygonum sibiricum polysaccharides (PSP) are one of the main active ingredients with the antidepressant activity, meanwhile the specific mechanisms of its action are still unclear. Recently, it is recognized by researchers that microglia play a double-edged role in neuroinflammation and the transformation of M1/M2 microglial phenotypes appears to be a potential therapeutic strategy in depression. Therefore, the present study evaluated the effects of PSP on microglial M1/M2 polarization and the molecular mechanisms were studied based on the lipopolysaccharide (LPS)-induced BV2 cell activation model. The results show that PSP significantly inhibited NO and LDH release and reduced ROS levels in LPS-induced BV2 cells. PSP could significantly reduce the protein expression level of Iba-1, decreased the mRNA levels of TNF-, IL-1 and IL-6, increased the mRNA level of IL-10. PSP also significantly reduced the protein expression level of CD16/32 and increased it of CD206, reduced the mRNA level and fluorescence intensity of iNOS and increased them of Arg-1. However, PSP pretreatment reversed the alterations of BDNF/TrkB/CREB and Notch/Hes1 pathways in LPS-induced BV2 cells. These results suggested that PSP exerted the anti-inflammatory effects by inhibiting M1 phenotype polarization and promoting microglia polarization toward M2 phenotype, and its regulation of microglia M1/M2 polarization may be associated with modulating the BDNF/TrkB/CREB and Notch/Hes1 pathways.