Impacts of Erythropoietin on Vascular Endothelial Growth Factor Receptor 2 by the Extracellular Signal-regulated Kinase Signaling Pathway in a Neonatal Rat Model of Periventricular White Matter Damage

Abstract

To explore the impacts of erythropoietin on vascular endothelial growth factor receptor 2 (VEGFR2) by the extracellular signal-regulated kinase (ERK) signaling pathway in a neonatal rat model of periventricular white matter damage. All of postnatal day 4 rats were randomized into three groups: the sham group [without hypoxia-ischemia (HI)], the HI group (HI with saline administration), and the erythropoietin (EPO) group [HI with recombinant human erythropoietin (rh-EPO) administration]. Rat pups underwent permanent ligation of the right common carotid artery, followed by 6% O2 for 2 hours or sham operation and normoxic exposure. Immediately after the HI, rats received a single intraventricular injection of rh-EPO (0.6 IU/g body mass) or saline. ERK and phosphorylation-ERK were examined at 60 minutes and 90 minutes after operation, and VEGFR2 were detected at 2 and 4 days after operation by using Western blot. At 60 minutes and 90 minutes after operation, the proteins of phosphorylation-ERK were significantly higher in HI rats than in the sham rats and significantly higher in HI+EPO rats than in the HI rats (P<0.05). Two days after operation, VEGFR2 was not significantly different between sham and HI rats. However, the proteins of VEGFR2 were increased after administration of rh-EPO (P<0.05). Four days after operation, the proteins of VEGFR2 were significantly higher in HI rats than in the sham rats and significantly higher in HI+EPO rats than in the HI rats (P<0.05). EPO may regulate VEGFR2 expression by affecting the intracranial ERK signaling pathways.