Figure 6.

EPs alleviated the OD-associated deficits of adult neurogenesis in the hippocampus. (A) Representative pictures of vertically and horizontally aligned BrdU (red) and GFAP (green) double-labeled RGL progenitor cells in SGZ of dentate gyrus. (B) Quantitative analysis of the number of BrdU-labeled RGL progenitor cells in SGZ (n = 11 slices from 3 mice). (C) Quantitative analysis of the cell alignment modes in three groups (n = 11 slices from 3 mice). (D-E) Confocal photomicrographs and Quantification of Tbr2⁺ progenitor cells in SGZ (n = 9 slices from 3 mice). (F) Confocal photomicrographs of double labeling of act-casp3 (red) and DCX (green), a marker for immature neurons. Nuclei were counterstained with Hoechst (blue). (G) Quantification of total DCX⁺ cells (n = 9 slices from 3 mice). (H) The percentage of DCX and act-casp3 double-labeled cells in DG significantly increased in OD-mice compared to that in Chow, indicating more newly generated immature neurons went to apoptosis. n = 11 slices from 3 mice. (I) Based on morphology, DCX-positive immature neurons can be divided into two subtypes. Type Ⅰ of DCX⁺ cells with processes short than the height of GCL, the younger neurons. Type Ⅱ of DCX⁺ cells with longer processes into the molecular layer, the differentiated neurons. (J) Distribution of two types of DCX ⁺ cells across three groups. The percentage of type I DCX-positive neurons in OD was significantly higher than that in Chow, indicating more newly generated neurons remained in differentiating stage in OD. (K) Images depicting the migration of newly generated neurons double-labeled with BrdU (red) and Prox1 (green), a specific marker for dentate granule cells. The migration index was shown in L. n = 33 cells from 3 mice. (M) EPs promoted the ratio of survived BrdU⁺ cells in OD-fed mice. (N) Phagocytosis by microglia (green) involves a ball-and-chain structure formed by microglial terminal branches clearly distinguishable from the microglial cell body (N2). The microglial phagocytic pouch is shown in detail: a pyknotic nucleus (N1) located in the body of DCX⁺ cells (N3) is undergoing phagocytosis. Nuclei were counterstained with Hoechst (blue). (O) The percentage of DCX⁺ cells phagocytic by microglia (n = 9 slices from 3 mice). In C and J, the same lower letter indicates no significant difference. Statistical significance compared to OD group by one-way ANOVA, adjusted for multiple comparisons by Dunnett post-hoc test. Lines in boxes represent median, top and bottom of boxes represent first and third quartiles, and whiskers represent 1.5 interquartile range.