Expression of angiogenic factors in rabbit spinal cord after transient ischaemia

It is known that angiogenic factors are induced in brain by ischaemia, and new vessel formation is correlated with better prognosis in patients of stroke. However, the role of angiogenesis and expression of angiogenic factors in spinal cord ischaemia is uncertain. We here investigated expression of three highly potent angiogenic peptides, i.e. basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) in the rabbit spinal cord after transient ischaemia, by Western blot and immunohistochemical analysis. Western blot analysis revealed that bFGF was induced at 8 h after transient ischaemia and decreased thereafter. Immunoreactive VEGF was also induced at 8 h, and it disappeared thereafter. HGF was not detected in the spinal cord with sham-operation or ischaemic injury. By immunohistochemical analysis, bFGF was weakly expressed in only a few small interneurons in sham-operated spinal cords. However, it was induced to a marked degree in motor neurons and interneurons of the anterior horn at 8 h after reperfusion. It was also induced in small neurons of the posterior horn. The expression in the anterior horn decayed thereafter though it lasted until 7 d in the posterior horn. VEGF was not expressed in sham-operated spinal cords, but the expression was induced in large motor neurons and interneurons at 8 h with marked reduction at 1 d. In contrast, HGF was not expressed in the spinal cord with sham-operation or ischaemic injury. These factors are known to play pivotal roles in angiogenesis, regulation of blood flow, and protection of endothelial cells. Through induction of these angiogenic peptides, protection of vascular endothelial cells and improvement of regional blood flow might be occurring in the spinal cord after ischaemia.