Exogenous administration of glial cell line-derived neurotrophic factor improves recovery after spinal cord injury

The aim of present study was to examine whether systemically delivered glial cell-derived neurotrophic factor (GDNF) was beneficial in reversing the spinal cord injury (SCI) in a spinal cord compression model. Rats were divided into three major groups: (1) sham operation (laminectomy only); (2) laminectomy + SCI + normal saline (1 ml/kg, i.v.); (3) laminectomy + SCI + GDNF (50 ng/kg, i.v.). Spinal cord injury was induced by compressing the spinal cord for 1 min with an aneurysm clip calibrated to a closing pressure of 55 g. GDNF or saline was administered immediately after SCI via the tail vein. Behavioral tests of motor function measured by maximal angle an animal could hold to the inclined plane were conducted at days 1-7 after SCI. The triphenyltetrazolium chloride staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling assay were also conducted after SCI to evaluate spinal cord infarction and apoptosis, respectively. Both GDNF and vascular endothelial growth factor (VEGF) in the injured spinal cord were assayed by immunofluorescence. It was found that systemically delivered GDNF, but not vehicle solution, significantly attenuated the SCI-induced hind limb dysfunction and spinal cord infarction and apoptosis. Both GDNF and VEGF could be detected in the injury spinal cord after GDNF, but not vehicle solution, therapy. The results indicate that GDNF treatment may be beneficial in reversing hind limb dysfunction by reducing spinal cord infarction and apoptosis in a spinal cord compression model.