VEGF enhance cortical newborn neurons and their neurite development in adult rat brain after cerebral ischemia

To study the effect of VEGF overexpression on development of cortical newborn neurons in the brains after stroke, we injected human VEGF165-expressive plasmids (phVEGF) into the lateral ventricle of rat brains with a transient middle cerebral artery occlusion (MCAO). An injection of phVEGF significantly promoted angiogenesis (BrdU+-von Willebrand's factor+) and reduced infarct volume in the rat brain after MCAO. Single labeling of 5′-bromodeoxyuridine (BrdU) and double staining of BrdU with lineage-specific neuronal markers were used to indicate the proliferated cells and maturation of newborn neurons in the brain section of rats at 2, 4, and 8 weeks after MCAO. The results showed that BrdU positive (BrdU+) cells existed in ipsilateral frontal cortex within 8 weeks after MCAO and reached the maximum at 2 weeks of reperfusion. The phVEGF treatment significantly increased BrdU+ cells compared with the control plasmid (pEGFP) injection. Cortical neurogenesis was indicated by the presence of newborn immature (BrdU+-Tuj1+), newborn mature (BrdU+-MAP-2+), and newborn GABAergic (BrdU+-GAD67+) neurons. All these neurons declined within 8 weeks after MCAO in the controls. Injection of phVEGF significantly increased BrdU+-Tuj1+ neurons at 2 weeks, and BrdU+-MAP-2+ neurons and BrdU+-GAD67+ neurons at 4 and 8 weeks, respectively after MCAO. Moreover, phVEGF treatment significantly increased neurite length and branch numbers of BrdU+-MAP-2+ newborn neurons compared with pEGFP treatment. These results demonstrate that VEGF enhances maturation of stroke-induced cortical neurogenesis and dendritic formation of newborn neurons in adult mammalian brains.