Introduction: It has been demonstrated that NF-kappaB (NF-kappaB) as a well-known transcription factor is activated after subarachnoid hemorrhage (SAH) onset. However, the existent researches only sketched the role of NF-kappaB in early brain injury after SAH, and the panoramic view of NF-kappaB activation remains obscure. In the current study, we aim to investigate the phases of NF-kappaB activation in vitro and vivo experiments and the downstream gene expression for further studies.
Methods: Cultured neurons were treated with hemoglobin to produce the neuron SAH injury model in vitro. In the present study, the cultured neurons were divided into 7 groups: control groups, without any special treatment; 1h, 3h, 6h, 12h, 24h, 48h groups of hemoglobin injury model. One-hemorrhage SAH model in New Zealand rabbits was induced with the cisterna magna arterial blood injection methods. Forty New Zealand rabbits were signed into 6 groups (4 or 8 rabbits per group): control groups, just experience the operation procedures without blood injection; day 1, 3, 6, 10, 14 groups of SAH model. Electrophoretic mobility shift assay (EMSA) was performed to access the NF-kappaB activation both in vivo and vitro. Immunohistochemistry was used to detect the location of activated NF-kappaB, Real-time PCR were performed to assess the downstream gene expression of NF-kappaB respectively. Nissl staining and LDH quantification were used to distinguish the neuron injury in vivo and vitro respectively.
Results: NF-kappaB DNA binding activity showed dual elevated phases after SAH in rabbits(day 1 to day 3 and day 10 groups). Meanwhile, in cultured hemoglobin-induced neuron injury model, NF-kappaB DNA binding activity showed significantly increase and biphasic peaks (1h and 24h groups) after exposed to hemoglobin. The down-stream gene expression showed an accordant peak phases detected by real-time PCR. The Nissl staining and LDH quantification results suggested neurons damage role for the early peak and no deteriorated effect for the late peak.
Conclusions: In vitro and in vivo studies, we showed that the biphasic NF-kappaB activity is induced both in hemoglobin-induced neuron injury and rabbit SAH model, and the early peak indicated injury role on neurons survive, and the late peak denied deteriorated role on neuron fate.
Patient Care: If we can explore the exactly inflammatory mechanism after SAH, and get a thorough description of NF-kappaB activation, we will get a more efficient anti-inflammation way to treat brain injury induced by SAH.
Learning Objectives: We aim to discover the molecular mechanism of brain injury after SAH, especially the NF-kappaB activation in vivo and vitro experiment.