OLIG2 and neuromyelitis optica: Myelin alteration was confirmed at D21 by proteolipid protein (PLP) labeling (mean decrease of fluorescence intensity, 39.5 ± 0.1 %) and associated the loss of olig2-positive oligodendrocytes in the NMO-rats compared to the Control-rats (39.6 ± 7.6 versus 66.8 ± 16 positive cells per field, respectively, p < 0000,1).