VEGF and flt - Expression time kinetics in rat brain infarct

Background and Purpose Vascular endothelial growth-vascular permeability factor (VEGF) is a candidate for an angiogenic and hyperpermeability inducing factor in an infarct because it is a secretable mitogen specific for endothelial cells and is upregulated by hypoxia. Our study attempts to clarify the chronological expression of VEGF and its receptor (fit) system in experimental cerebral infarction. Methods With the use of a reproducible middle cerebral artery occlusion model in rats, VEGF expression was identified by Western blotting with anti-VEGF antibody. The chronological expression of the VEGF/flt system was analyzed semiquantitatively by immunohistochemical means in infarcts with different time courses from 3 hours to 3 weeks. Results VEGF and fit were expressed exclusively in the ischemic brain. The bands obtained on the immunoblot at 38 and 45 kD are related td those of VEGF(121) and VEGF(165) isoforms. Macrophages, neurons, and glial cells chronologically expressed VEGF immunoreactivity in a different fashion. Both VEGF (bound) and fit were detected in endothelial cells along with the development of angiogenesis. Conclusions In the ischemic brain the macrophages, neurons, and glial cells appear to contain VEGF. The VEGF receptor fit was induced in endothelial cells along with the progression of angiogenesis in infarct. The VEGF/flt system is thus considered to be involved in the healing process of brain infarct.