9-cis-Retinoic Acid and 1,25-dihydroxy Vitamin D3 Improve the Differentiation of Neural Stem Cells into Oligodendrocytes through the Inhibition of the Notch and Wnt Signaling Pathways

Background: differentiating oligodendrocyte precursor cells (opcs) into oligodendrocytes could be improved by inhibiting signaling pathways such as wnt and notch. 9-cis-retinoic acid(9-cis-ra) and 1,25-dihydroxyvitamin d_3(1,25[oh]_2d_3) can ameliorate oligodendrogenesis. we investigated whether they could increase oligodendrogenesis by inhibiting the wnt andnotch signaling pathways.methods: cortical neural stem cells were isolated from 14-day-old rat embryos and cultured using the neurosphere assay. the cells were treated in 4 different conditions for 1 week: the negative control group received only the basic fibroblast growth factor, the positive control group received only t3 without growth factors, the ra group was treated with 9-cis-ra, and the vit d3 group was treated with 1,25(oh)_2d_3. the effects of 9-cis-ra and 1,25(oh)_2d_3 on the level of the myelin basic protein (mbp) and the gene expression of the sox10, mbp gene, hes5, and lrp6 were studied using flow cytometry and real-time pcr. the data were analyzed using one-way anova with graphpad prism. a p value less than 0.05 was considered significant. results: the mrna expressions of the sox_10, mbp, and mbp gene were significantly increased in the treated groups compared with the negative control group; the increase was similar in the 9-cis-ra group and the positive control group. furthermore, 9-cis-ra significantly decreased the expression of the hes5 gene, a notch signaling pathway transcription factor, and 1,25(oh)_2d_3 significantly reduced the expression of the lrp6 gene, a wnt signaling pathway co-receptor. conclusion: it seems that 9-cis-ra and 1,25(oh)_2d_3 are good candidates to improve the differentiation of opcs into oligodendrocytes.