Distinct patterns of intracerebral hemorrhage-induced alterations in NF-κB subunit, iNOS, and COX-2 expression

Transcription factor nuclear factor-kappa B (NF-kappa B), plays a key role in regulating inflammation in brain pathologies. The goal of this study was to characterize temporal changes in NF-kappa B activation, NF-kappa B subunit expression, and expression of selected NF-kappa B-regulated gene products [inducible form of nitric oxide synthase (iNOS) and cyclooxygenase-2], at the transcriptional and translational level in the brain after intracerebral hemorrhage (ICH). Employing the intrastriatal injection of autologous blood in rats to model ICH, we demonstrated, using NF-kappa B-DNA binding assay, a robust and prolonged NF-kappa B activation, starting as early as 15 min after the onset of ICH. Consequently, we demonstrated that the mRNA and protein for p50, p52, p65, c-Rel, and RelB NF-kappa B subunits, as well as I kappa B alpha were all up-regulated, with a time course ranging from minutes to days following ICH, depending on the subunit. Using reverse transcription-polymerase chain reaction to analyze mRNA and immunoblotting to analyze protein in ICH-affected tissue, we found robust induction of iNOS at both mRNA and protein levels that followed a time-course similar to changes in p65, p52, and RelB mRNA. Oddly, in contrast to iNOS, cyclooxygenase-2 mRNA and protein following an early transient increase demonstrated significant reduction in response to ICH. In summary, NF-kappa B activation occurs within minutes and persists for at least a week in response to ICH. This reaction utilizes different NF-kappa B regulatory subunits and is associated with the expression of selected target genes.