Abstract
Effects of amyloid β-protein fragment 25 - 35, AβP(3P(25 - 35), on the membrane permeability of organic molecules were examined in the brain neurons dissociated from rats by using an argon laser (equipped in flow cytometer and laser microscope) and a combination of two fluorescent dyes, fluo-3-AM and ethidium bromide. AβP(25 - 35) at concentrations of 1 μM or greater induced both leakage of fluo-3 from the neurons and permeation of ethidium across the membrane in a dose-dependent manner, although both dyes are highly impermeant to the intact plasma membrane. Thus, AβP(25 - 35) seems to increase not only membrane permeability of inorganic ions such as Ca2+, Na+ and K+, as previously suggested, but also that of organic molecules. Therefore, the brain neuron membrane is suggested to lose its integrity in the presence of AβP(25 - 35) that leads to neuronal death.
