Fig. 2

Alterations on spinal microglia with aging and obesity. a) Microglia in the dorsal horn of lumbar spinal cord was labeled with Iba1 (red). While there was no obvious difference among the groups of 3 mo, 6 mo and DIO 6 mo mice, the density of Iba1⁺ microglia was higher in lean and DIO 17 month-mice. b) Total number of Iba1+ cells was significantly increased in lean 17 month-mice compared to lean 3 month-mice (^xxx p < 0.001, lean 3 vs. lean 17) which was further increased in DIO 17 month-mice (n = 6–10 section/animal, n = 3 animals/group, +++p < 0.001, lean 17 vs. DIO 17, ###p < 0.001, DIO 6 vs. DIO 17). c) Iba1⁺ microglia (red) underwent morphological changes with aging and obesity. It was observed that cell bodies were enlarged (arrowheads) and processes were retracted (arrows) while more lipofuscin granules (yellow) were accumulated in these enlarged cell bodies with aging and obesity. d) Microglia clusters were found in the spinal cord white matter of aged mice (square in lean 17 month-mice), not found in lean 3 and 6 month-mice. Confocal scanning images showed that clusters were composed of 5-7 microglia and contained less lipofuscin granules