Enhanced expression of the CXCl12/SDF-1 chemokine receptor CXCR7 after cerebral ischemia in the rat brain

Expression patterns of the second SDF-1 receptor RDC1/CXCR7 were examined after focal ischemia in rats using in situ hybridization. CXCR7 mRNA was identified in the ventricle walls as well as neuronal, astroglial, and vascular cells. After ischemia, intact cortical regions showed a rapid, 4 days-lasting increase in neuronal CXCR7 expression. In the ischemic tissue CXCR7 expression was scarce and associated with blood vessels. Between days 2 and 10 after ischemia-onset, SDF-1 expression increased strongly in the peri-infarct and infarct region, which was accompanied by the appearance of numerous CXCR4-expressing but not CXCR7-expressing cells. These patterns suggest that SDF-1 may influence vascular, astroglial, and neuronal functions via CXCR7 and mediate cell recruitment to ischemic brain areas via CXCR4.