ABSTRACT
The morphological changes in the anterior horn of the L4 and L5 spinal segments were observed following anterior root avulsion in the adult male Sprague-Dawley rat (300~350 gm) at 5 days, 1 week, 2 weeks and 3 weeks postlesion. The animals were perfused with 4% paraformaldehyde, 0.15% picric acid in 0.1 M phosphate buffer solution and cryostat sections were prepared. Immunohistochemistry was used to identify changes of the phenotype in the anterior horn cells. Primary antibodies, goat anti-choline acetyltransferase (ChaT, 1 : 500, Chemicon), mouse antirat ED-1 (1 : 200, Serotec), rabbit anti-glial fibrillary acidic protein (GFAP, 1 : 200, DAKO) and rabbit anti-vascular endothelial growth factor (VEGF, 1 : 500, Santa Cruz Biotechnology) were used. Avidin-Biotin complex method was performed for immunohistochemical reaction and color reaction was developed with DAB-H2O2. Following results were observed in the anterior horn of lumbar spinal cord; 1. The number of ChaT-immunoreactive (ir) cells were reduced 20% level of control animals at 3 weeks after avulsion. 2. ED-1-ir microglia were significantly increased at 1 week and processes of ED-1-ir microglia surrounded around the axotomized neuronal cell bodies. 3. Gliosis defined by extensive GFAP immunoreactivity was observed both ipsilateral and contralateral side of lesion but the VEGF-ir cells were significantly increased in the ipsilateral side of lesion. Therefore, this study suggested that the majority of axotomized motor neurons were degenerated and the cellular proliferation and phenotype changes including glial cell activation were observed in the lumbar spinal cord after anterior root avulsion of adult rats.