Figure 1
Temporal dynamics of cellular responses after excitotoxic lesion. (A) Treatment protocols. (B) (Upper panel) Immunoblot analyses of inosine 5-monophosphate dehydrogenase (IMPDH)2 and β-actin at different time points post-lesion. N-methyl-D-aspartate (NMDA) lesion affected IMPDH2 immunoreactivity over time. (Lower panel) Semiquantitative analyses of immunoblot data (n = 4) showed a significant reduction in the amount of IMPDH2 at 36 and 48 hours after injury compared with the values at 12 hours (*P < 0.05). (C) Confocal laser scanning microscopy images, double-labeled with isolectin (I)B4 (microglial cells, green) or glial fibrillary acidic protein (GFAP) (astrocytes, green) each in combination with Ki-67 (proliferating cells, red). Temporal patterns of (D) microglial and (E) astroglial proliferation indices after NMDA-mediated excitotoxic lesion as shown by quantitative morphometry of Ki-67+ glial cell ratios (*P < 0.05 vs. control (CTL)). Microglial proliferation indices were significantly increased from 12 hours to 48 hours, with maximum values at 24 hours post-lesion. Astrocytic proliferation indices were significantly increased from 12 hours to 36 hours after injury. (F–G) Microglial and astroglial apoptosis indices after NMDA-mediated excitotoxic lesion as measured by assessment of ratios of cleaved caspase-3-immunoreactive glial cells (*P < 0.05 vs. control (CTL)). The apoptosis indices of both microglial cells and astrocytes were significantly increased between 24 and 72 hours, with a decline at 36 hours post-lesion. Scale bar = 50 μm