Decreased α7 nicotinic acetylcholine receptor protein levels in sporadic Alzheimer's disease hippocampus

Alzheimer's disease pathology is characterized by the presence of neuritic plaques enriched in beta-amyloid peptide(1-42) (A beta(1-42)) and the loss of cholinergic functions in the brain. A beta(1-42) binds to a neuronal pentameric cation channel, the alpha 7 nicotinic acetylcholine receptor (alpha 7nAChR), with high affinity and modulates two processes critical in memory formation, calcium homeostasis and neurotransmitter release. We compared the protein levels of intact alpha 7nAChR in the hippocampi of Alzheimer's disease patients (n=10) and age-matched non-demented control subjects (n=10) using gel electrophoresis and Western blot analysis. We showed that the alpha 7nAChR protein was significantly reduced by 54% (p<0.0001) in Alzheimer's disease hippocampi. The possibility of developing a biochemical marker of Alzheimer's disease by monitoring the changes in alpha 7nAChR protein levels in a relevant accessible tissue is discussed.