Figure 6.

Evidence that MAO activity exerts a long-lasting effect on the proliferative capacity of NSC in the developing telencephalon. A, Images of neurospheres in cultures prepared from the VZ/SVZ of the dorsal telencephalon of E14.5, E17.5, and P2 MAO AB KO and WT littermate mice. Scale bar, 1.0 mm. B, C, Sizes of first generation (B) and second generation (C) neurospheres established from telencephalic tissues of WT and MAO AB KO mice of the indicated ages. Values are the mean and SEM (n = 3–4 mice). *p < 0.05, **p < 0.01. D, Levels of MAO A and MAO B activities in neurospheres cultured from WT and MAO AB KO mice of the indicated ages (E12.5, E15.5, and P2). Note that cultured NS exhibit MAO A, but not MAO B activity, and MAO A activity significantly increases as development proceeds. E, Levels of MAO A activity in E17.5 neurospheres measured 24 h after treatment with the indicated concentrations of clorgyline (an inhibitor of MAO A). F, G, Clorgyline administration did not significantly alter the diameter (F) or number (G) of neurospheres in cultures established from P2 cortical tissue. H, Low concentrations of serotonin (10 and 100 ng/ml) stimulate neurosphere formation in P2 cultures from WT mice, but not in cultures from MAO AB KO mice. Values are the mean and SEM (n = 3–4 mice). **p < 0.01 compared with the value for cultures not exposed to serotonin.