Influence of the Human Amyloidogenic precursor on Epithelial and Neuronal Cell Membrane*

The pathology of Alzheimer’s disease (AD) is correlated with the amyloid fiber formation. The Aβ (1-42) amyloid fragment is the principal species associated with senile plaque. There is evidence that the Aβ (1-42) amyloid precursors, such as the monomers, dimers, oligomers, and the proto-fibrils are toxic to the neuronal cell. It is believed that the Aβ (1-42) amyloid precursors perturb the neuronal cell membrane integrity leading to its death; however, the molecular mechanism by which the neuronal cell death occurs is not yet understood. Dielectric relaxation spectroscopy was used to study the interaction of the oligomeric Aβ (1-42) with the cell membrane of epithelial and neuronal cells. We incubated both cell types with the Aβ (1-42) solution of monomers, oligomers, and fibrils. We measured the dielectric response of the incubated cells at different concentrations over a wide range of frequencies (from 10^-2 Hz to 10⁷ Hz). Two dispersion processes (α, β) can be observed for all concentrations of the cell suspensions. We observed changes in the conductivity and permittivity of the neuronal cells when incubated with Aβ (1-42), which suggests the toxicity of the precursors causing marked alterations in the electrical properties of the cell membrane.