BACKGROUND: The Glasgow Coma Scale, computer tomography, and nuclear magnetic resonance imaging have been frequently used to diagnose brain injury. However, these methods do not accurately and quantitatively evaluate injury degree. However, proteomics displays some advantages. To date, there are few proteomics studies based on primary astrocyte cultures from a fluid percussion injury model.OBJECTIVE: To detect differential protein expression in rat cerebral cortical astrocytes following fluid percussion injury using two-dimensional gel electrophoresis and mass spectrum and to determine specific biological markers of brain injury.DESIGN, TIME AND SETTING: Complete, randomized grouping and proteomics experiments were performed at the Molecular Pathological Laboratory, Central Laboratory and Tianjin Key Laboratory for Biomarkers of Occupational and Environmental Hazard of Medical College of Chinese People's Armed Police Force from October 2007 to May 2008.MATERIALS: Inverted phase-contrast microscope was purchased from Olympus, Japan. PROTEAN IEF Cell isoelectric focusing electrophoresis system and PROTEAN II Xi-Cell vertical electrophoresis system were purchased from Bio-Rad, USA. Autoflex MALDI-TOF mass spectrometer was purchased from Bruker, Germany. METHODS: A total of 90 culture dishes, fully coated with Sprague Dawley rat cortical astrocytes, were randomly divided into control (n = 30) and injury (n = 60) groups. Astrocytes in the injury group were subjected to fluid percussion and subdivided into 4-hour (n = 30) and 48-hour injury (n = 30) groups.MAIN OUTCOME MEASURES: Cell morphology was observed using inverted phase-contrast microscopy. Cell total protein was extracted from each group, followed by two-dimensional gel electrophoresis and silver staining, and the differential protein expression was analyzed using PDQuest 7.0 software. Protein peptide mass fingerprinting of differential protein spots was obtained by matrix assisted laser desorption/ionization-time of flight mass spectrometry. The National Center for Biotechnology Information (NCBI) protein database was retrieved by Mascot to primarily identify protein type. Finally, differential protein expression was detected by Western blot analysis. RESULTS: Following fluid percussion injury, astrocytes displayed obvious swelling and increased intercellular space, with some cell detachment; the number of dead cells was significantly greater than the control group (P < 0.05). Expression intensity of 114 protein spots was significantly greater in the injury group compared with the control group (P < 0.05); 9 of the 114 protein spots were identified and peptide matching scores of 8 spots were > 61 (P < 0.05). Protein types were identified and included cellular retinol binding protein, brain fatty acid binding protein 7, S100 calcium binding protein A11, 60S acidic ribosomal protein P2, calponin 3, breast carcinoma amplified sequence 2 homolog, eukaryotic translation initiation factor 1A, and hypothetical protein LOC685814. Western blot detection revealed brain fatty acid binding protein 7 expression in cortical astrocytes, which increased with injury time compared with the control group (P < 0.05).CONCLUSION: Results from this study showed morphological and proteomic changes in cortical astrocytes following fluid percussion injury. Brain fatty acid binding protein 7 was expressed in astrocytes and possibly played an important role in injury repair. Mass-spectrum identified differentially expressed proteins that correlated with cell metabolism regulation, signal transduction, and translation initiation, and could serve as specific biological markers of brain injury.