Intracellular Zn2+ levels are decreased in primary hippocampal culture neurons after treatment with soluble Aβ. A) In hippocampal cell cultures (DIV15), a fraction of applied Aβ1-40 HiLyte Fluor™ 555 can be found intracellular, after removal of extracellular Aβ by washing steps, colocalizing with Zn2+ stained by Zinpyr-1 (arrows). B) After treatment of hippocampal neurons (DIV15) with 1 μM and 10 μM Aβ1-40, a reduction in dendritic Zn2+ signals (arrows) can be seen. The mean grey value of Zinquin signals inside dendrites was measured from five cells and the ratio between cells treated for 6 or 24 h and untreated cells is shown. A significant reduction can be seen after 6 h (10 μM) and 24 h (1 μM and 10 μM) treatment.