Effects of moderate hypobaric hypoxic preconditioning on the expression of the transcription factors pCREB and NF-kappaB in the rat hippocampus before and after severe hypoxia.

Preconditioning using three sessions of moderate hypobaric hypoxia, i.e., hypoxic preconditioning (HP), increased the tolerance of susceptible brain neurons to severe hypoxia and other harmful factors. The study addressed changes in the expression of transcription factors NF-kappaB (nuclear factor kappa B) and CREB (cAMP response element binding protein) in the hippocampus of rats preconditioned with moderate hypoxia. Immunocytochemical methods demonstrated that HP increased immunoreactivity for NF-kappaB and phosphorylated CREB (pCREB) in hippocampal fields CA1-CA4 and the dentate gyrus and promoted increases in the expression of these transcription factors in the hippocampus of preconditioned rats 3-24 h after severe hypobaric hypoxia. These data provide evidence that NF-kappaB and CREB are involved in the mechanisms forming HP-induced tolerance of the brain.