Early PBM treatment prevents ELA-induced OLs apoptosis and reduction in mature oligodendrocytes. A (a-c) and C (a-c) Representative immunofluorescence staining for TUNEL+ (green) - labeled OLs (Olig2+, red) in CA1 region of the hippocampus, small images exhibit a representative single cell from each group. B (a) and D (a) Representative synthetic protein bands of Olig2 in the hippocampus, corresponding peak areas were normalized with the level of total protein. B (b) and D (b) Results of quantitative analysis of Olig2 protein levels. B (c) and D (c) Percentage of TUNEL+ - labeled OLs (TUNEL+ Olig2+ cells) in the total Olig2+ population. A (d-f) and C (d-f) Representative immunofluorescence staining for mature oligodendrocyte (CC1, green) with DAPI. B (d) and D (d) Quantification of CC1+ cells. ELA-exposured rats exhibited a marked increase in the proportion of oligodendrocyte apoptosis, accompanied by reductions in Olig2 protein content and mature oligodendrocyte (CC1), which was reversed by early PBM treatment. Scale bar = 40 µm. All data are presented as mean ± SE (n = 5-7). * P < 0.05 versus Control-group; # P < 0.05 versus ELA-group.