ObjectiveTo explore the expression of mannose receptor on microglia and its difference in different brain areas in the mouse, in order to understand better the microglial function. MethodsThe expression of mannose receptor on microglia was revealed by using immunofluorescencent double-labeling technique either in ten normal brains (Iba-1 ) and ten inflammatory brains induced by unilaterally cerebroventricular injection of lippolysaccharide (LPS) or six brains with a acute inflammation induced by intraperitoneal injection of LPS in C57 adult mice. The comparison of the expressions in different brain regions（cortex, hippocampus, striatum, substantia nigra and cerebellum）was done in those normal and inflammatory mice, respectively. ResultsThe expression of mannose receptor (CD206) showed clearly in part of microglia (both of Iba-1 positive cells and OX-6 positive cells) either in normal and inflammatory cortex. The CD206 positive cells were 83% and 94% in total cortical microglia, respectively. The activated microglia (OX-6 positive cells) in total CD206 positive cells were 79%,81%,74%,53% and 66% in the cortex, hippocampus, striatum, substantia nigra and cerebellum, while the CD206 positive cells in activated microglia were 63%,48%,49%,53% and 52%, respectively. ConclusionEither the rest or activated microglia express mannose receptors and this expression can be enhanced by brain inflammation. This expression has also a regional difference in the brain. The ratio of activated microglia in total CD206 positive cells is lower in substantia nigra than that in other brain areas, while the ratio of CD206 positive cells in activated microglia is lower in hippocampus.