Figure 4.

p75^NTR-positive SVZ cells respond neurogenically to BDNF stimulation. P2 SVZ cells were sorted for p75^NTR expression by flow cytometry. a, b, After plating in the presence or absence of BDNF and culturing for 7 d, sized-matched neurospheres were induced to differentiate for 48 h, and the number of neurospheres containing β-III-tubulin-positive neurons (a) and the number of β-III-tubulin-positive neurons per neurosphere (b) were quantified for each population. The majority of neurospheres derived from p75^NTR-high cells contained neurons compared with less then 20% of neurospheres derived from p75^NTR-negative cells. Under basal conditions, p75^NTR-high cells also produced more neurons per neurosphere than p75^NTR-negative cells (ANOVA; p = 0.014). c–e, After treatment with 0 (c), 30 (d), or 100 (e) ng/ml BDNF, p75^NTR-high cells showed a dose-dependent increase in the number of β-III-tubulin-positive neurons (red) per neurosphere, but there was no significant effect on neuron number in the p75^NTR-negative cultures. f, g, When differentiated and immunostained, p75^NTR-high (f) and p75^NTR-negative (g) cells sorted from the P2 SVZ generated neurospheres that were found to contain GFAP- (blue), O4- (green), and β-III-tubulin (red)-positive cells. Scale bars, 20 μm. *p < 0.05; **p < 0.01; ***p < 0.001; mean ± SD; n = 3 experiments.