Fig. 2

Oligodendrocyte processes align with cortical axons and γ-secretase inhibitors (GSIs) facilitate myelination. Cortical co-cultures were treated with the GSI, DAPT or DMSO as described in Fig. 1. a On 13 DIV, cells were fixed and stained with antibodies to the axon marker SMI 31/32 neurofilament protein (red) and MBP (green). Image at the right is a composite of the SMI 31/32, MBP, and DAPI. Arrowheads indicate regions of MBP alignment with axon. Bar 100 µm. b Left two panels show entire image fields taken from a 96-well plate immunostained for Olig2 and MBP. Bars 200 µm. Boxed regions are enlarged in the middle panel to show morphological detail of MBP-stained OLs. Bar 50 µm. Two images at right depict the digital mask of MBP staining intensity of the adjacent image (middle panel) and the far right image are tracings of MBP alignment used to calculate fiber length. Bars 50 µm. c Raw data from three DAPT dose response experiments was quantified from images as in b and compiled from n = 3 experiments, 80 image fields per concentration, mean ± SEM. Asterisk (*) denotes P values versus DMSO of <0.0001; ANOVA with Bonferroni post hoc test. There was a significant effect of four compound concentrations compared to DMSO [F(9, 19) = 83.82, P < 0.0001]. Post hoc comparisons indicated that the mean score for the concentrations 0.37 μM (M = 21.32, SEM = 1.3), 1.11 μM (M = 27.88, SEM = 1.9), 3.33 μM (M = 33.51, SEM = 1.9), 10 μM (M = 37.1, SEM = 2.5) was significantly different than DMSO