Vascular endothelial growth factor rescues hippocampal neurons from glutamate‐induced toxicity: signal transduction cascades

Abstract

Vascular endothelial growth factor (VEGF) is known as a selective endothelial cell mitogen that promotes angiogenesis and increases blood vessel formation in vivo. Here we report that VEGF has protective effects on primary hippocampal neurons against glutamate toxicity by acting on phosphatidylinositol 3‐kinase (PI3‐K)/Akt pathways and mitogen‐activated protein kinase kinase (MEK)/extracellular signal‐regulated kinase (ERK) pathways, operating independently of one another. Decrease in the VEGF's neuroprotective effect resulting from inhibition of either pathway alone was significantly enhanced by simultaneous inhibition of both pathways. However, adenovirus‐mediated expression of either the active form of Akt or of MEK significantly inhibited glutamate‐induced neuronal death. Treatment with antisense ODN against Flk‐1, but not against Flt‐1, blocked the effect of VEGF on the activation of Akt and ERK and glutamate‐induced neuronal death. These findings suggest that VEGF has a protective effect on hippocampal neurons against glutamate‐induced toxicity and that this effect is dependent on PI3‐ K/Akt and MEK/ERK signaling pathways mediated primarily through Flk‐1 receptor.