Induction of vascular endothelial growth factor receptor-3 mRNA in glial cells following focal cerebral ischemia in rats.

To identify whether vascular endothelial growth factor receptor (VEGFR)-3, a receptor for VEGF-C and VEGF-D, is involved in pathophysiology of stroke, we investigated the spatiotemporal regulation of VEGFR-3 mRNA after transient focal cerebral ischemia. Most of the increase in VEGFR-3 expression in the ischemic core could be attributed to brain macrophages, whereas VEGFR-3 in the peri-infarct penumbra region was predominantly expressed in reactive astrocytes. A subpopulation of VEGFR-3-expressing brain macrophages was positive for NG2 proteoglycan and showed proliferative activity. In addition, in vitro model of stroke revealed no significant induction of VEGFR-3 in activated microglial cells, indicating that infiltrating exogenous macrophages expressed VEGFR-3 after focal ischemia. These data suggest that VEGFR-3 may be involved in the glial reaction and possibly in the recruitment of monocytic macrophages during ischemic insults.