Objective To investigate which cells persistantly express interleukin (IL)-1β during the transition of acute neuroinflammaiton to chronic neuroinflammaiton and therefore to provide the evidences of targeted therapy for blocking neuroinflammation.Methods A single does of lipopolysaccharide (LPS) (2 mg/kg,LPS group) or 0.9％ saline (Control group) was intraperitoneally injected in aged rats.Level and gene expression of IL-1β in hippocampual tissue were measured by enzyme-linked immunosorbent assay (ELISA) and real time polymerase chain reaction (RT-PCR),respectively.Cells secreted IL-1β in hippocampus was detected via double fluorescence.Results Glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule-1 (IBA-1) positive cells were significantly increased day 1 (P ＜ 0.05) and latee on,gradually return to base level 30 days after LPS exposure.These changes were consistent with mRNA expressions of IL-1β and astrocytes-derived IL-1β in hippocampus.Neither IL-1β expressed in microglia nor in neurons was observed at any time point following LPS-treated.Conclusions LPS induces prolonged activation of glial cells and sustained expression of astrocytes-derived IL-1β,which may play an important role in the transition of acute neuroinflammation to chronic neuroinflammation.