Objective To investigate the effect and possible mechanisms of Oligomeric β-amyloidSUB>1-42/SUB>-induced inflammatory responses in microglia on neuronal cells. Methods BV-2 microglial and Neuro-2A neuronal-like cells were cultured EM>in vitro/EM>. Conditioned media from Oligo-AβSUB>1-42/SUB> stimulated BV-2 cells (Aβ-CM) was performed. Neuro-2A cells viability were measured by MTT assay. And the percentage of apoptotic or necrotic neuronal cells were evaluated by epifluorescence microscopy after stained with AO-EB. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and prostaglandin E2 (PGESUB>2/SUB>) le BR>vels were determined by ELISA assay. Nitric oxide (NO) levels were detected by Greiss assay. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins were detected by Western blotting. Results Treatment of neuronal cells with conditioned media from Oligo-AβSUB>1-42/SUB>-stimulated in BV-2 cells (Aβ-CM) resulted in a more dramatic decrease in the viability of Neuro-2A cells when compared to the Oligo-AβSUB>1-42/SUB> alone group when the concentration of induced Oligo-AβSUB>1-42/SUB> was at 1.0 and 5.0μmol/L (P<0.05,P<0.01). The combined groups(Aβ-CM+Aβ) showed significant interaction between Aβ-CM and Aβ(1.0μmol/L) by two-way ANOVA. Further, the percentage of apoptotic and necrotic neuronal cells was increased gradually and significantly with increasing concentrations of Aβ in CM by AO-EB stain assay. Me