Acute effect of β amyloid on synchronized spontaneous Ca²⁺ oscillations in cultured hippocampal networks

The effects of β amyloid (Aβ) on cytoplasmic Ca²⁺ ([Ca²⁺]_c) have been studied extensively, but the current literature on this aspect is confusing. We reported that 20 μM Aβ_25-35 significantly inhibited the synchronized spontaneous cytoplasmic Ca²⁺ transients immediately after application, whereas it had little effect on the baseline [Ca²⁺]_c concentration in neurons. Aβ_1-42 had a similar effect on the Ca²⁺ transients as Aβ_25-35, while it increased baseline [Ca²⁺]_c concentration gradually. However, Aβ_1-40 had little effect on either Ca²⁺ transients or baseline [Ca²⁺]_c. Such differential effects of Aβ on Ca²⁺ signals might explain, at least partially, the confusing observations from the previous studies and provide important therapeutic implications for preventing or reversing early neuron damage in Alzheimer's disease.