Altered expression of Angiopoietins after cerebral trauma

grantor: University of TorontoAngiopoietin-1 stabilizes vascular endothelium by activation of the endothelial Tie-2 receptor, and Angiopoietin-2 is a competitive antagonist of Angiopoietin-1/Tie-2 interaction. The role of these ligands in blood-brain barrier breakdown and cerebral angiogenesis post-trauma was studied in the rat cortical cold-injury model by examining their spatial and temporal mRNA and protein expression over a time-course of 6 hours to 6 days. Increased Angiopoietin-2 relative to Angiopoietin-1 mRNA and immunoreactivity was observed in the early phase post-injury. This suggests a role in blood-brain barrier breakdown and vascular remodeling. Two to 6 days post-injury, the progressive increase in Angiopoietin-1 and decrease in Angiopoietin-2 mRNA coincides with cerebrovascular angiogenesis, maturation of neovessels, and restoration of blood-brain barrier. There was no change in the basal Tie-2 mRNA and immunoreactivity after cold-injury. These results suggest that Angiopoietins are one of the factors regulating blood-brain barrier integrity and cerebrovascular angiogenesis post-injury.M.Sc