Figure 3.

Neurogenesis and DG injury induced by long-term VEGF exposure. A, Tetracycline-regulated transgenic system for VEGF expression in the brain. B, VEGF was induced (on) in adult (2 months) mice by tetracycline withdrawal and was kept in the on mode for the indicated periods. Littermates harboring only the driver transgene served as controls. C, VEGF-induced neurogenesis reflected in an increased number of DCX⁺ cells (neuroblasts and immature neurons) in the DG. Bottom, Quantification of DCX⁺ cells in the DG in hippocampi removed at the indicated times after VEGF induction. On the contrary to natural neurogenic decline in control mice, an elevated neurogenic rate persists throughout the 7 month period of continuous VEGF exposure. D, NeuN staining (labeling mature neurons) highlights dramatic neuronal loss in the DG of prolonged VEGF-expressing animals. Scale bar, 100 μm. Bottom, Average GCL area measured in NeuN-stained DG sections. For statistical details, see Table 1. *p < 0.005.