P4‐251: BETA AMYLOID OLIGOMER INTERNALIZATION VIA α7β2 NICOTINIC ACETYLCHOLINE RECEPTORS MAY CONTRIBUTE TO CHOLINERGIC CELL DEATH IN ALZHEIMER'S DISEASE

Background: Loss of central cholinergic neurons and accumulation of amyloid plaques are pathogenic features of Alzheimer’s disease (AD). Research has shown that a7-nicotinic acetylcholine receptors (a7-nAChR) mediate b-amyloid peptide (Ab) internalization and contribute to neuronal death. The a7b2-nAChR, a recently-discovered nicotinic receptor subtype, is expressed in the septum and hippocampus of the brain regions of cell death early in AD. Studies have not yet focused on a7b2 nAChR mediated internalization of Ab1-42. Based on previous research, a7b2 is suspected to have a higher affinity for Ab. Methods:Our study focused on comparing a7b2to a7-nAChR mediated internalization of Ab. SH-EP1 human neuroepithelial cell lines stably expressing a7-nAChRs (Fig 1A) or a7b2-nAChRs (Fig 1B), and wild type cells were incubated with oligomeric Ab1-42 or scrambled peptide (Fig 1C) followed by incubation with Amylo-Glo dye (Biosensis). Fluorescence intensity was compared to determine relative amounts of Ab internalization. Cell death assays were also performed. Results:Cells expressing a7-nAChRs had more internalized Ab versus cells with a7b2-nAChRs, but both were markedly higher than cells incubated with scrambled Ab1-42 and wild type cells. Notably, cells expressing a7b2-nAChRs had a high rate of cell death. This suggests that internalization by a7b2-nAChRs could contribute to loss of function and cell death in AD. Conclusions: These results provide new insights into mechanisms of intracellular Ab accumulation and cytotox-