Fig. 3. Inhibition of neurogenesis after irradiation is independent of p21.

a Loss of DCX+ cells in dentate gyrus is apparent in both p21+/+mice and p21−/− mice at 9 weeks after irradiation (DCX, green; DAPI, blue). b A proliferating neuroblast (arrow) demonstrates dual Ki67/DCX staining (Ki67, red; DCX, green; DAPI, blue). c A newborn neuron (arrow) demonstrates dual BrdU/NeuN immunoreactivity (BrdU, green; NeuN, red; DAPI, blue). d, e At 9 weeks after 5 Gy, there is loss of Ki67+ and BrdU+ cells in dentate gyrus independent of p21 genotype. f−h Absence of p21 results in an increase in DCX+ and BrdU+/NeuN+ cells in nonirradiated controls, but loss of DCX+ (f), Ki67+/DCX+ (g) and BrdU+/NeuN+ (h) cells after irradiation is independent of p21 genotype. BrdU (50 mg/kg/day × 7 consecutive days) was given at 4 weeks and animals were killed at 9 weeks after 0 or 5 Gy. Data are represented as mean ± SEM and analyzed using two-way ANOVA, *p < 0.05, †p < 0.01, §p < 0.001, post hoc Bonferroni test with 3-4 mice per genotype per time point