Fig 1: Oligodendrocytes and myelin basic protein in the dentate gyrus of the hippocampus correspond with individual outcomes of anxiety-like and avoidance behavior after acute stress.A Markers for immature and mature oligodendrocytes (OLs) and myelin selected for immunohistochemical analysis: GSTp, glutathione S-transferase pi; CAII, carbonic anhydrase II; MBP, myelin basic protein. B Representative GSTp, CAII, and MBP staining. Scale bar = 20 µm. DAPI, 4',6-diamidino-2-phenylindole. C Example coronal section with hippocampal, amygdala, and corpus callosum ROIs indicated in red. Scale bar = 2000 µm. D–I Representative images of each oligodendrocyte marker from the dentate gyrus of animals with low (score = 2) or high (score = 19) composite behavior scores. Scale bar = 100 µm. J Dentate gyrus GSTp measures from animals with low (2–6) and high (7 or more) composite behavior scores. All data are presented as mean ± SEM. Granule cell layer (GCL): low = 35.15 ± 2.64 cells/mm2, high = 49.16 ± 3.46 cells/mm2; two-tailed t test, t(9) = 3.11, p = 0.013. Hilus: low = 139.20 ± 14.40 cells/mm2, high = 178.30 ± 28.69 cells/mm2; two-tailed t test, t(9) = 1.14, p = 0.28. K CAII measures. GCL: low = 33.03 ± 3.75 cells/mm2, high = 38.57 ± 2.32 cells/mm2; two-tailed t test, t(8) = -1.26, p = 0.24, one high outlier removed. Hilus: low = 129.50 ± 22.95 cells/mm2, high = 164.40 ± 33.82 cells/mm2; two-tailed t test, t(9) = 0.82, p = 0.43. L MBP measures. GCL: low = 1366 ± 91 integrated fluorescence intensity/µm2, high = 1699 ± 74 integrated fluorescence intensity/µm2; two-tailed t test, t(9) = 2.86, p = 0.019. Hilus: low = 2496 ± 150 integrated fluorescence intensity/µm2, high = 3136 ± 142 integrated fluorescence intensity/µm2; two-tailed t test, t(9) = 3.09, p = 0.013. M Correlation matrix of composite behavior scores to oligodendrocyte and MBP measures from a subset of stress-exposed animals (Pearson correlations: n = 10–11; one high outlier removed from GCL CAII dataset; one high outlier removed from MoDG GSTp dataset). MoDG, molecular layer of dentate gyrus; SLu, stratum lucidum; Rad, stratum radiatum; LMol, lacunosum moleculare; Or, stratum oriens; LA, lateral amygdala; BLA, basolateral amygdala; CeA, central amygdala; cc, corpus callosum. N Correlation matrices of dentate gyrus oligodendrocytes and MBP from stress-exposed animals to composite scores derived from hierarchical behavior clustering (Pearson correlations: n = 10–11; one high outlier removed from GCL CAII dataset). *p < 0.05, **p < 0.01. O Immunomarkers for quantification of oligodendrogenesis. BrdU, bromodeoxyuridine; Olig2, oligodendrocyte transcription factor 2. P Representative images of BrdU and Olig2 immunolabeling. Arrows point to colabeled cells. Scale bar = 25 µm. Q BrdU/Olig2 colabeling measures: n = 6 per group. GCL: median low = 0 cells/mm2, median high = 1.43 cells/mm2; two-tailed Mann-Whitney test, U = 14, p = 0.57. Hilus: low = 3.48 ± 1.16 cells/mm2, high = 16.86 ± 2.71 cells/mm2; two-tailed t test, t(10) = 4.53, p = 0.0011.