Fig. 7.

Radiation-induced changes in neurogenesis are associated with indications of neuroinflammation. Two month-old C57BL6J mice were irradiated with whole brain doses ranging from 2 – 10 Gy and 2 months later, dual labeling immunohistochemistry and confocal microscopy were used to quantify the fractions of newly born (BrdU+) cells that were co-labeled with NeuN (neurons; left panel, light bars) or CD68 (activated microglia; left panel, dark bars). The significant decrease in numbers of newly born neurons was associated with a significant increase in the numbers of newly born activated microglia. When considered in terms of individual animals, when neurogenesis (percentage of BrdU+ neurons) was plotted against the percentage of BrdU+ activated microglia, there was a strong correlation (r = 0.83) suggesting a relationship between neuroinflammation and reduced neurogenesis. In the left panel each bar represents a mean of 4 mice; error bars are SEM. In the right panel each point represents a single animals. Reprinted from Fike et al (21) with permission.