EXPRESSION OF APOLIPOPROTEIN-E MESSENGER-RNA IN RAT MICROGLIA

Apolipoprotein E (apoE) is a major risk factor for Alzheimer disease ( AD), which is the most common cause of progressive dementing illness. ApoE has been postulated to be synthesized by astrocytes and taken up by microglia and neuronal cells. However, it remains unknown whether a poE is also produced by microglia in the brain. We analyzed apoE mRNA expression of microglia using a rat primary culture system. Reverse tr anscriptase-polymerase chain reaction (RT-PCR) analysis revealed expre ssion of apoE mRNA in cultured rat microglia. By RT-in situ-PCR, micro glia showed positive staining for the PCR product of apoE mRNA. These results indicated that apoE was biosynthesized in rat microglia. We su ggest that microglia might be one of the sources of apoE in the brain, and that apoE synthesized in microglia might be closely related to th e pathogenesis of AD.