Phloroglucinol ameliorates the reduction in dendritic synaptic density- induced by Aβ_1–42 in primary hippocampal neuron cultures.

<p>(A)(C) Representative images of dendritic spines on cultured primary hippocampal neurons at DIV 18. The dendritic segment, outlined with a white box (upper), is magnified to delineate spine morphology (bottom). The scale bars indicate 20 μm (low-scaled panel) and 1 μm (magnified panel). (B) Quantification of the spine density (secondary dendritic spines 50–100 μm from the soma) at DIV 18; the neurons were transfected at DIV 11 with IRES-mGFP. Treatment with hydrogen peroxide significantly decreased the spine density (4.27 ± 0.13 spines/10 μm, n = 43, ***<i>p</i> < 0.001) compared with the control treatment (7.07 ± 0.28 spines/10 μm, n = 50). The decrease in spine density induced by hydrogen peroxide was ameliorated by phloroglucinol (7.21 ± 0.28 spines/10 μm, n = 26, ^###p<0.001 vs. hydrogen peroxide-treated). (D) The dendritic spine density of neurons treated with Aβ_1–42 was significantly reduced (4.17 ± 0.28 spines/10 μm, n = 31, ***<i>p</i> < 0.001) compared to the control neurons (7.12 ± 0.28 spines/10 μm, n = 31). Adding phloroglucinol to the primary hippocampal neurons treated with Aβ_1–42 significantly alleviated the reduction in dendritic spine density (6.93 ± 0.36 spines/10 μm, n = 41, ^###p<0.001 vs. Aβ_1–42-treated). The statistical analyses were performed via one-way ANOVA, and the data are presented as the means ± SEM (**<i>p</i> < 0.01 or ***<i>p</i> < 0.001 vs. control, ^###p<0.001 vs. hydrogen peroxide or Aβ_1–42-treated).