[Expression of Ephrin-B2 after focal cerebral ischemia in rats]

To explore the expression profile of Ephrin-B2 in the ischemic penumbra after transient focal cerebral ischemia in rats, and to clarify the mechanism of Ephrin-B2 triggering angiogenesis.

Sprague-Dawley rats were randomly divided into a normal group, a sham operation group and ischemic-reperfusion 1, 3, 7, 14, and 28 d groups. Suture-occluded method was used to establish the focal middle cerebral artery occlusion model and the ischemic brain was reperfused 2 h after the occlusion. Western blot and quantitative real-time reverse-transcription polymerase chain reaction were used to detect the dynamic expression profile of Ephrin-B2 in the penumbra cortex. Double immunofluorescence was used to speculate the location and the co-expression of Ephrin-B2 in blood vessels, neurons and astrocytes. Microvessel density was quantified by the number of CD31+ cells. Rats were subjected to neurologic functional tests by modified neurological severity scores (mNSS) before sacrifice.

Compared with the sham group, Ephrin-B2 protein and mRNA level of the penumbra cortex in the ischemic group increased 3 days (P<0.05) after the reperfusion, peaked at day 7 and 14 (P<0.01), and declined at day 28. Double immunofluorescence indicated that Ehprin-b2 was expressed in the neurons, blood vessels and astrocytes; mNSS peaked at day 7, and gradually declined at day 14. The microvessel density of penumbra cortex in the ischemic group increased 3 days (P<0.05) after the reperfusion, peaked at day 14 (P<0.01), and gradually declined at 48 h.

Cerebral ischemia reperfusion induces the over-expression of Ephrin-B2, with a dynamic trend, suggesting that Ehprin-b2 may improve post-stroke functional recovery by enhancing angiogenesis and neurogenesis.