Fig. 1.

Lithium treatment 4 weeks after irradiation increased proliferation but not neuronal maturation in the GCL on PND 77. a Timeline of the in vivo experimental design showing that lithium treatment was started 4 weeks after irradiation; three different time points (PND 77, 91, and 105) were investigated to assess the early as well as late effects of lithium on neurogenesis. b BrdU immunoreactivity in the GCL of the different treatment groups at PND 77. Scale bar = 100 µm. ×20 magnification. c Interleaved dot plot graph of BrdU quantification in GCL showing the effect of lithium treatment in the Sham (*p = 0.0485) and Irr groups (*p = 0.0471). Two-way ANOVA shows that both irradiation and lithium treatments had an effect: irradiation (F_1,16 = 57.77, ^####p < 0.0001), lithium (F_1,16 = 12.45, **p = 0.0028). d DCX immunoreactivity in the GCL of the different treatment groups on PND 77. Scale bar = 100 µm. ×20 magnification. e Interleaved dot plot graph of DCX quantification in the GCL on PND 77. Two-way ANOVA revealed an effect of irradiation but not lithium treatment: irradiation (F_1,16 = 127.3, ^####p < 0.0001), lithium (F_1,16 = 1.34, p = 0.7974). Lithium treatment did not alter the density of DCX-positive cells in Sham (p = 0.8097) or Irr (p > 0.9999) groups. f Representative images of the dendritic tracing in DCX⁺ cells for all experimental groups. g Cell body area (µm²) shows that lithium treatment significantly decreased the size of the immature cells both in Sham and Irr groups at PND 77. h Dot plot graph of the dendritic complexity of DCX⁺ immature neurons showing lower complexity in ShamLi, Irr, and IrrLi compared with Sham at PND 77. Circle, triangle, and square marks represent the value for each neuron in each animal. N (number of animals) = 3 in each group. Number of traced neurons is 15–20 in each animal. Linear mixed model, *p < 0.05, **p < 0.01, ***p < 0.001. Error bars represent point estimate and 95% confidence interval. i Sholl analysis of DCX⁺ immature neurons showing that lithium treatment reduced the number of intersections in the distal part (50–60 µm) of the dendrites at PND 77 in Sham but not in Irr brains. Error bars represent SEM ****p < 0.0001; **p < 0.01; *p < 0.05