Glial and neuronal serum markers after controlled cortical impact injury in the rat

The aim of this study was to investigate the time course and the correlation of glial fibrillary acidic protein (GFAP), protein S-100B, and neuron specific enolase (NSE) serum levels to the severity of traumatic brain injury in rats. Male Wistar rats (n = 65 S-100B, NSE group and n = 55 GFAP group) underwent a severe cortical impact injury (100PSI, 2 mm deformation). Blood samples were drawn directly after trauma, 1 h, 6 h, 12 h, 24 h, and 48 h post trauma as well as in sham operated animals directly after craniotomy, after 6 h and 48 h. Serum levels at different severities were estimated in 20 rats (45PSI, 75PSI, 2 mm deformation). We found a time-dependent release of NSE and GFAP into serum after trauma. The highest NSE values were detected six hours after trauma (31.5 micrograms/l, mean, p < 0.0001), the highest GFAP levels were measured one hour after trauma (0.079 microgram/l, mean, p < 0.0014). Additionally we found a close relationship between NSE serum levels and the severity of traumatic brain injury (45PSI = 12.7 micrograms/l, 75PSI = 16.17 micrograms/l, 100PSI = 28.45 micrograms/l, p < 0.05). S-100B serum levels showed an increase (0.92 microgram/l, p < 0.005) but no time-dependent release. S-100B and GFAP showed no relationship to trauma severity. Serum levels of GFAP, S-100B and NSE are significantly elevated in the early phase after experimental traumatic brain injury. In this experimental model of cortical impact injury only NSE, but not GFAP and S-100B serum levels are time-dependently correlated with the severity of cortical impact.