Specific uptake of Abeta1-40 in rat brain occurs in astrocyte, but not in microglia.

In the brain of a patient with Alzheimer's disease, beta amyloid peptide (Abeta) is thought to be taken up by glial cells such as astrocyte and microglia to be degraded. However, it is unclear whether the Abeta is absorbed by astrocyte or microglia. The purpose of our study is to determine which type of glial cell, astrocyte or microglia, can take up Abeta. Beta amyloid 1-40 (Abeta1-40) was directly infused into the frontal cortex or hippocampus for 14 days. Dual-labeling immunohistochemistry for Abeta1-40 with an astrocytic (GFAP) or microglial (CD11b) marker was performed to examine co-localization of Abeta1-40 and glial markers. In the Abeta1-40 infused site, immunoreactivity of Abeta1-40 was observed only in astrocytes, not in microglia. In addition, Abeta40-1, a reverse peptide of Abeta1-40, was not taken up by astrocytes. These results suggested that the astrocyte-specific uptake of Abeta occurred in the rat brain.