The Pattern of DNA and Histone H3 Methylation in Rat Brain in Response to Severe Hypobaric Hypoxia and Hypoxic Postconditioning

Abstract

Methylation of histone H3 Lys4 (meН3К4) and Lys9 (meН3К9), as well as DNA methylation (meDNA), was investigated in rat hippocampal and neocortex neurons in an original model of severe hypobaric hypoxia (SHH) and hypoxic postconditioning (PostC). It was shown that, in hippocampal field CA1, a day after SHH, the content of meH3K4 increased, while the level of meDNA decreased. Later, the amount of meH3K9 decreased and the meDNA content increased. PostC increased meH3K4, normalized the level of meH3K9, and decreased the level of meDNA in the hippocampal field CA1 of rats that had survived SHH. In the neocortex, significant changes were detected only 1–2 days after SHH, consisting in the stimulation of histone H3 methylation and decreased meDNA. Thus, a complex pattern of changes in the methylation of H3 histone and DNA was observed in both the hippocampus and neocortex in response to SHH. However, the protective effect of PostC was accompanied by the correction of only hippocampal reactions, while methylation in the neocortex returned to the initial level regardless of the PostC.