Blockade of EphB2 enhances neurogenesis in the subventricular zone and improves neurological function after cerebral cortical infarction in hypertensive rats

EphB2/ephrinBs has been recently demonstrated to regulate cell proliferation in the neurogenic subventricular zone (SVZ). However, little is known about the role of EphB2 in adult neurogenesis following cerebral infarction. In the present study, we investigated the role of EphB2 in proliferation and differentiation of precursor cells within the SVZ, as well as the neurological function recovery after permanent middle cerebral artery occlusion (MCAO) in hypertensive rats. Bromodeoxyuridine (BrdU) was given twice per day starting from 24h after MCAO for 6-consecutive days. Recombinant EphB2-Fc or IgG-Fc was preclustered by incubation with anti-human Fcγ and then intraventricularly administrated at 24h after MCAO. The neurological function was evaluated before operation and at 7, 14 and 21 days after MCAO respectively. The infarct size and immunoreactivities of BrdU, Nestin, DCX, GFAP and NeuN were measured at 7, 14 and 21 days after MCAO respectively. Treatment with EphB2-Fc markedly improved the neurological function recovery within 3 weeks after MCAO. In parallel, EphB2-Fc significantly increased the number of BrdU-labeled cells and led to marked increases in BrdU+/DCX+ and BrdU+/Nestin+ cells within the ipsilateral SVZ for 2 weeks after MCAO respectively (all p < 0.05). The BrdU+/NeuN+ cells in the peri-infarct area and neighboring ipsilateral striatum were significantly increased following EphB2-Fc infusion within 3 weeks after MCAO (all p < 0.05). Our data suggest that administration of exogenous clustered EphB2-Fc at 24h can enhance the endogenous neurogenesis and concomitantly improve neurological recovery after cerebral infarction.