Figure 1

Somatic applications of Aβ peptides induce a dying-back pattern. a. Schematic representation of a two-chamber microfluidic device (2-C μFD) with two cell culture chambers interconnected by funnel-shaped micro-channels [8] (a': cross-section of the microfluidic device. A neuron is represented. Note that only axons can reach the right chamber). b-f. Fluorescence microscopy analysis of axonal degeneration vs somatic status after addition of Aβ peptide in the left (soma) vs right (distal part of axons) chambers. Cortical neurons were grown for 12 days in two-compartment chips and each chamber was treated for 48 h with Aβ peptides as indicated. The two left micrographs show the somato-dendritic chamber after staining with anti-MAP2 (red), DAPI (blue) and Thioflavine S (green). The right rectangular micrographs show the distal chamber after immunostaining with anti-α-tubulin and labeling with Thioflavine S. Each central scheme represents the device with indicated localization of treatment (left chamber vs right chamber): b) control cultures (Ø/Ø), c) somato-dendritic treatment with Aβ 25-35 peptide (Aβ/Ø, 30 μM), d) axonal treatment with Aβ 25-35 peptide (Ø/Aβ, 30 μM), e) somato-dendritic treatment with glutamate (Glut/Ø, 10 μM), f) somato-dendritic treatment with glutamate combined with axonal treatment Aβ 25-35 (Glut/Aβ, 10 μM/30 μM). Scale bar: 20 μM. g) Quantification of axonal fragmentation. Aβ25-35, glutamate (Glut), and control Aβ35-25 were added, or not (Ø), to the chamber as indicated. Axonal fragmention index was calculated as described in Methods section (n = 3; **P < 0.01; ***P < 0.001, ANOVA).