To investigate whether astragaloside (AST) Ⅳ could inhibit lipopolysaccharide (LPS)-induced activation of astrocytes and the possible mechanism.

Effects of different concentrations of AST Ⅳ on astrocyte viability were determined by MTT to select the optimum concentration for the following experiments. Primary astrocytes were induced by LPS to construct the inflammatory model. Astrocytes were divided into three groups: PBS, LPS and LPS+ AST Ⅳ (LPS+ AST Ⅳ) groups. The release of nitric oxide (NO) was detected by Griess method. Expression of glial fibrillary acidic protein (GFAP), an astrocyte marker, and TLR4 were analyzed by immunohistochemistry and Western blot. Cytokines of IL-6, TNF-α, IL-4 and IL-10 in the supernatants of cell culture for 24 h collected after stimulation were measured by ELISA.

AST Ⅳ significantly inhibited the LPS-induced activation of astrocytes and NO release (P<0.01), suppressed the expression of TLR4 (P<0.05) and reduced the secretion of IL-6 (P<0.01) and TNF-α (P<0.01), but increased the secretion of IL-4 and IL-10 (P<0.05 and P<0.01).

AST Ⅳ could significantly inhibit the LPS-induced activation of astrocytes and suppress inflammatory responses, and the possible mechanism might be related to reduced secretion of inflammatory factors after blocking the expression of TLR4.

Activation of astrocyte; Astragaloside Ⅳ; Toll-like receptor 4(TLR4)