Object: Results of recent studies indicate that erythropoietin (EPO) produces a neuroprotective effect on experimental subarachnoid hemorrhage (SAH). It has been reported that S-100 protein levels increase in cerebrospinal fluid (CSF) after SAH, providing a highly prognostic indication of unfavorable outcome. This study was conducted to validate further the findings of S-100 protein as an index of brain damage and to assess whether treatment with recombinant human EPO (rhEPO) would limit the increase of S-100 protein level in CSF following experimental SAH.
Methods: Thirty-two rabbits were each assigned to one of four groups: Group 1, control; Group 2, SAH; Group 3, SAH plus placebo; and Group 4, SAH plus rhEPO (each group consisted of eight rabbits). The rhEPO and placebo were administered to the rabbits after SAH had been induced, and S-100 protein levels in the CSF of these animals were measured at 24, 48, and 72 hours after the experimental procedure. In each group of animals levels of S-100 protein were compared with the mortality rate, neurological outcome, and neuronal ischemic damage. High S-100 protein levels were found in rabbits in Groups 2 and 3, which exhibited poor neurological status and harbored a high number of damaged cortical neurons. Favorable neurological outcome and significant reductions in total numbers of damaged neurons were observed in animals in Group 4 in which there were significantly lower S-100 protein concentrations compared with animals in Groups 2 and 3 (p < 0.001).
Conclusions: The results of this study support the concept that determination of the S-100 protein level in CSF has prognostic value after SAH. The findings also confirm that rhEPO acts as a neuroprotective agent during experimental SAH.