Vascular endothelial growth factor in Alzheimer's disease and experimental cerebral ischemia.
Several growth factors have been implicated in the pathogenesis of Alzheimer's disease (AD). We considered whether the vascular endothelial growth factor (VEGF) is involved in the vascular pathology associated with most cases of AD. We observed enhanced VEGF immunoreactivity in clusters of reactive astrocytes in the neocortex of subjects with AD compared to elderly controls. VEGF reactivity was also noted in walls of many large intraparenchymal vessels and diffuse perivascular deposits. In addition, we established that astrocytic and perivascular VEGF reactivity was enhanced in cerebral cortex of rats subjected to cerebral ischemia and to chronic hypoxia; experimental conditions known to be associated with astrogliosis and angiogenesis. We suggest the increased VEGF reactivity, also observed in infarcted human brain tissue, implicates compensatory mechanisms to counter insufficient vascularity or reduced perfusion (oligemia) apparent in AD.