The senile plaque (SP) is one of the pathological hallmarks in the brains of patients with Alzheimer's disease (AD), but the mechanism of its formation and its role in AD progression are not yet fully understood. Synthetic amyloid β-protein (Aβ)1-40 is known to aggregate in vitro, and the aggregated Aβ has been widely used for in vitro experiments, in which its peculiar effects on neuronal and glial cells have been shown. To date, however, the formation of a SP-like structure in a culture system using synthetic Aβ has not been demonstrated. In this study, we established a possible SP model using synthetic Aβ1-40 and rat glial cultures as follows: (1) large spherical aggregates of synthetic Aβ (sAmys) were produced from synthetic Aβ1-40 (10-50 μm in diameter), (2) the sAmys were added to a glial culture, and (3) the characteristics of the sAmys and the reactions of glial cells (microglia and astrocytes) around the sAmys were analyzed. We found that the sAmys exhibited the same features as the dense amyloid core in SPs, including the intense green birefringence under polarized light with Congo red, and induced reactive features in glial cells, including induction of major histocompatibility complex class II antigen in the microglia and interleukin-1β in the astrocytes, similar to those seen in SPs in the brain in AD. Given our findings, we consider that this glial culture system with the sAmys is a possible in vitro SP model and useful for investigating the effects of massive amyloid deposition on neuronal and glial cells. (C) 2000 Academic Press.
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