Lipopolysaccharide induces astrocyte activation and downregulates the expression of Kir4.1 channel

To explore the influence of lipopolysaccharide (LPS) on the activation of astrocytes and the expression of the inwardly rectifying K(+) channel Kir4.1.Astrocytes were separated from the cerebral cortex of newborn SD rats and cultured in the presence of LPS or LPS combined with interleukin-1 receptor antagonist (IL-1ra). The cell vitality was detected by MTT assay; the expression of glial fibrillary acidic protein (GFAP) was analyzed by immunocytochemistry; the production of IL-1β was tested by ELISA; the expression of Kir4.1 and IL-1β mRNAs were determined by quantitative real-time PCR.LPS promoted the activation of astrocytes in a time- and dose-dependent manner. LPS significantly increased the production of IL-1β and the expression of IL-1β mRNA, while decreased the expression of Kir4.1 mRNA in cultured astrocytes. Compared with the LPS group, IL-1ra could effectively reversed the above two results.The cultured astrocytes could be activated by LPS; LPS-induced downregulation of Kir4.1 mRNA in cultured astrocytes might be related with the inflammatory cytokine IL-1β.