Fig. 5: DDC treatment rescued the deficits of adult hippocampal neurogenesis, newborn neuron development, and hippocampus-dependent learning in HMF-exposed mice.

a Experiments timeline for cell proliferation analysis in GFM- and HMF-exposed mice with or without DDC treatment. b–d Quantification of numbers of BrdU⁺Sox2⁺GFAP⁺ cells (b), BrdU⁺Sox2⁺GFAP⁻ cells (c), and active caspase-3⁺ DCX⁺ cells (d) in GFM- and HMF-exposed mice with or without DDC treatment. GMF + Vehicle, n = 4 mice, GMF + DDC, n = 4 mice, HMF + Vehicle, n = 4 mice, HMF + DDC, n = 4 mice. P values were determined using two-tailed unpaired t test. e Experiments timeline for cell differentiation analysis in GFM- and HMF-exposed mice with or without DDC treatment. f–h Quantification of numbers of BrdU⁺ cells (f), BrdU+NeuN⁺ cells (g), and BrdU⁺S100β⁺ (h) cells in GFM- and HMF-exposed mice with or without DDC treatment. GMF + Vehicle, n = 4 mice, GMF + DDC, n = 4 mice, HMF + Vehicle, n = 4 mice, HMF + DDC, n = 4 mice. P values were determined using two-tailed unpaired t test. i Timeline of experiments for the in vivo labeling and analyses of newborn neurons in the DG of mice, followed by DDC treatment. j Representative images of RFP⁺ newborn neurons in GFM- and HMF-exposed mice with or without DDC treatment. Scale bar = 50 μm. k, l Quantification of the dendritic length (k) and dendritic complexity (l, GMF + Vehicle versus GMF + DDC, UNIANOVA, F(1, 200) = 2.381 p = 0.124; HMF + Vehicle versus HMF + DDC, UNIANOVA, F(1, 113) = 23.84 P < 0.001) of RFP⁺ newborn neurons in the DG. GMF + Vehicle, n = 71 neurons from four mice, GMF + DDC, n = 131 neurons from four mice, HMF + Vehicle, n = 32 neurons from four mice, HMF + DDC, n = 76 neurons from four mice. Data were analyzed by UNIANOVA analysis, and the two-tailed unpaired t test for two-group comparisons. m Schematic drawing of novel location and object location test. n, o Quantification of the ratio of exploration time on novel objective location (n) and novel objective object (o) in GFM- and HMF-exposed mice with or without DDC treatment. GMF + Vehicle, n = 9 mice, GMF + DDC, n = 9 mice, HMF + Vehicle, n = 9 mice, HMF + DDC, n = 8 mice. P values were determined using the two-tailed unpaired t test. p Schematic drawing of fear conditioning test. q, r The percentage analysis of freezing behavior during fear conditioning tests (q, contextual test; r, cue test) in GFM- and HMF-exposed mice with or without DDC treatment, GMF + Vehicle, n = 9 mice, GMF + DDC, n = 9 mice, HMF + Vehicle, n = 9 mice, HMF + DDC, n = 8 mice. P values were determined using the two-tailed unpaired t test. The data in (k) were presented in the whisker plot with defined elements, median (centerline), upper and lower quartiles (bounds of box), and highest and lowest values (whiskers). Other data are presented as mean ± SEM. Tukey’s multiple comparisons test was performed to analyze the mean of each group with the mean of every other group.