THE EFFECT OF MILD HYPOBARIC HYPOXIA IN PRECONDITIONING REGIME ON THE EXPRESSION OF PCREB AND NF-κB TRANSCRIPTION FACTORS IN RAT HIPPOCAMPUS BEFORE AND AFTER SEVERE HYPOXIA
Preconditioning using threefold mild hypobaric hypoxia (HH) is known to increase the tolerance of vulnerable brain neurons to severe hypoxia and other damaging factors. In the present study, the changes of the expression of transcription factors NF-κB (nuclear factor kappa B) and CREB (cAMP response element binding protein) were studied in the hippocampus of rats preconditioned by mild hypoxia. Using immunocytochemical method, it was demonstrated that HH increased NF-κB and phosphorylated CREB (pCREB) immunoreactivity in CA1-CA4 fields of the hippocampus and gyrus dentatus. It also contributed to the up-regulation of the expression of these transcription factors in the hippocampus of preconditioned rats 3-24 h following severe HH. These findings suggest that NF-κB and CREB are involved in HH-activated mechanisms of brain tolerance development.