INCREASED BASIC FIBROBLAST GROWTH-FACTOR EXPRESSION FOLLOWING CONTUSIVE SPINAL-CORD INJURY

Neurotrophic factors appear to be crucial for the survival and potenti al regeneration of injured neurons. We have previously demonstrated th at contusive spinal cord injury (SCI) increases the levels of mRNA for basic fibroblast growth factor (FGF2). To determine whether FGF2 prot ein levels also increase, Western blot analysis was performed on extra cts of spinal cord tissue after a standardized SCI and compared to lam inectomy controls, In spinal cord extracts, a monoclonal antibody to F GF2 recognized various molecular forms of FGF2 (18-24 kDa) and some ch aracteristic proteolytic fragments. Extracts of spinal cords 1 day aft er SCI showed a slight increase in the levels of these polypeptides. B y 4 days, a significant increase (twofold) was detected ill the levels of the 18-kDa and higher molecular weight forms as well as the proteo lytic fragments. Immunohistochemical analyses on spinal cord tissue se ctions confirmed an increased cellular (glial) FGF2 as well as interst itial immunoreactivity surrounding neurons and along blood vessels. He parin-purified spinal cord extracts from tissue 4 days after SCI showe d increased biological activity as indicated by their ability to (i) i ncrease [H-3]thymidine incorporation in cultures of Balb/c 3T3 cells a nd (ii) induce phosphorylation of suc-associated neurotrophic factor-i nduced tyrosine-phosphorylated target, a FGF2 target protein. These da ta suggest that SCI induces increased FGF2 expression and support the hypothesis that FGF2 may play a role in the partial recovery of functi on seen following SCI. (C) 1996 Academic Press, Inc.