Acidic fibroblast growth factor (aFGF; also known as FGF-1) is a potent neurotrophic factor that affects neuronal survival in the injured spinal cord. However, the pathological changes that occur with spinal cord injury (SCI) and the attribution to aFGF of a neuroprotective effect during SCI are still elusive. In this study, we demonstrated that rat SCI, when treated with aFGF, showed significant functional recovery as indicated by the Basso, Beattie, and Bresnahan locomotor rating scale and the combined behavior score (p < 0.01-0.001). Furthermore proteomics and bioinformatics approaches were adapted to investigate changes in the global protein profile of the damaged spinal cord tissue when experimental rats were treated either with or without aFGF at 24 h after injury. We found that 51 protein spots, resolvable by two-dimensional PAGE, had significant differential expression. Using hierarchical clustering analysis, these proteins were categorized into five major expression patterns. Noticeably proteins involved in the process of secondary injury, such as astrocyte activation (glial fibrillary acidic protein), inflammation (S100B), and scar formation (keratan sulfate proteoglycan lumican), which lead to the blocking of injured spinal cord regeneration, were down-regulated in the contusive spinal cord after treatment with aFGF. We propose that aFGF might initiate a series of biological processes to prevent or attenuate secondary injury and that this, Spinal cord injury (SCI)1 is a costly disease as well as the most frequent cause of mortality and morbidity in every medical care system around the world (1, 2). Traumatic axonal injury is a primary sequela of contusive SCI and is characterized by axonal swelling and disconnection of the ascending sensory and descending motor tracts (3). Contusive SCI seems to initiate a complicated cascade of pathophysiological changes, a process called secondary injury, including fiber deformation, increased vascular permeability, local ischemia, intraneuronal edema, and local demyelination. Moreover traumatic axonal injury typically involves a disruption of the axonal membrane, and this results in up-regulation of the entry of calcium, the influx of which initiates calpain activation (4, 5) and mitochondrial injury/swelling (6), resulting in cytochrome c release and caspase activation (7). Simultaneously the proliferation and hypertrophy of astrocytes around the injury site are characterized by increased immunoreactivity to glial fibrillary acidic proteins (GFAPs) (8).Although many studies have focused on revealing the pathophysiology of SCI, the exact molecular mechanisms and the biochemical pathways that mediate secondary injury remain sketchy (9). Spinal cord injury often causes permanent neurological deficits mostly because the injured neurons lack regenerative ability, and the series of destructive processes that follow SCI results in a second wave of cell death and spreading tissue loss (10). Therefore, studies of the stimulaFrom the ‡Institute

Abbreviations used: aFGF, acidic fibroblast growth factor; Anp, acidic nuclear protein; ED1, ectodermal dysplasia 1; GFP, Green Fluorescent Protein; IEF, isoelectric focusing; IFN-c, interferon-c; IL-1, interleukin-1; iNOS, inducible nitric oxide synthase; IpG, immobilized pH gradient; LPS, lipopolysaccharide; MCP-1, macrophage chemoattractant protein 1; NO, nitric oxide; NOS, nitric oxide synthase; PAL31, proliferation related acidic leucine-rich protein; PKA, protein kinase A; SCI, spinal cord injury; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; siRNA, small interfering RNA; STAT-1, signal transducer and activator of transcription-1; TNF-a, tumor necrosis factor-a. AbstractFunctional regeneration in a complete T8 transection model Cheng et al. (1996) and most recently, acidic fibroblast growth factor (aFGF; also known as FGF-1) involved in the repair process of the spinal cord injury (SCI) rat Tsai et al. (2008) have been reported. To further reveal the mechanism of the repair process of SCI, in additionally, we have identified a 30 kDa specific protein kinase A substrate induced at 6 days after SCI. However, the induction of the transducing signal was reduced in samples treated with aFGF. The 30 kDa protein was purified and identified by mass spectrometry as a novel protein, PAL31. The results of immunohistochemical study showed that PAL31 is abundantly expressed in the epicenter of the injured spinal cord and colocalizes with ED1-positive cells (macrophages) and CD8 T lymphocytes. Over-expression of PAL31 in RAW 264.7 cells resulted in the down-regulation of macrophage chemoattractant protein 1, inducible nitric oxide synthase, and signal transducer and activator of transcription-1. However, knockdown of PAL31 by small interfering RNA seems to lead to apoptosis when the cells were treated with inflammatory inducers. These experimental results suggest that PAL31 may involve in the modulation of the inflammatory response and, at the same time, prevent apoptosis process of macrophage after SCI. Keywords: apoptosis, inducible nitric oxide synthase, inflammation, macrophage chemoattractant protein 1, PAL31, signal transducer and activator of transcription-1, spinal cord injury.