Figure 4

PIPE-791 induces OPC differentiation. (A) Dissociated rat oligodendrocyte precursor cells were treated with PIPE-791 and immunostained with an antibody against MBP (green) and the OPC marker PDGFRα (white). A dose dependent increase in MBP⁺ oligodendrocytes was observed. Graphs plotted as vehicle subtracted percent of T3 induced differentiation (EC₅₀ 108 nM, mean ± SEM, n = 6). Values were compared by ANOVA with Dunnet’s vs vehicle: ****p < 0.0001; T3 was p < 0.0001 by t-test to vehicle). A₁, representative image at 1 µM PIPE-791. Scale bar: 50 µm. (B) PIPE-791 induces oligodendrocytes that can myelinate axons in a rat cortical myelination assay. Cells were immunostained against MBP (green), Tuj1 (white), and counterstained with Hoechst (blue). Linear myelin segments were measured to obtain a myelination index, resulting in an EC₅₀ of 2.6 nM. 1 µM AM152 was used as a positive control, mean ± SEM, n = 4. Values were compared by ANOVA with Dunnett’s vs vehicle, ****p < 0.0001; AM152 was p < 0.0001. B₁, representative image at 300 nM PIPE-791. Scale bar: 25 µm. (C) PIPE-791 (300 nM) increases MBP⁺ rat oligodendrocytes despite the presence of inhibitory macrophages (mean ± SEM, t-test vs vehicle no macrophages, n = 8).