Protein oxidation and enzyme susceptibility in white and gray matter with in vitro oxidative stress: relevance to brain injury from intracerebral hemorrhage.

Intracerebral hemorrhage (ICH) is a devastating stroke sub-type with high mortality and morbidity. ICH frequently occurs in subcortical white matter generating hematomas that contain high heme iron levels. In this study, we examined the consequences of iron-induced oxidation (1-100 microM Fe2+ for 30 min. or 50 microM Fe2+ for 1-120 min.) on the activities of two oxidatively sensitive enzymes, creatine kinase (CK) and glutamine synthetase (GS), and on an oxidative stress marker, protein carbonyl formation, in porcine cerebral cortical white and gray matter. In vitro iron oxidation produced time and concentration dependent decreases in both CK [maximum decreases of 49.3+/-1.2% and 44.3+/-4.1% (average +/- SEM, N=3) for white and gray matter, respectively] and GS activities (maximum decreases of 16.9+/-1.7% and 13.2+/-1.0% for white and gray matter, respectively) and increases in protein carbonyl formation. Interestingly, protein carbonyl concentrations were significantly greater (p<0.05) in white vs. gray matter at 100 microM iron (30 min.) and 50 microM iron (120 min.). Additionally, CK and GS activities were lower for white versus gray matter at several time points and iron concentrations. It is our hypothesis that iron induced oxidative stress contributes to the pathogenesis of perihematomal brain injury following ICH.