Effects of different hypobaric hypoxia regimes on the expression of corticosteroid receptors in the rat hippocampus

Hippocampal gluco- and mineralocorticoid receptors (GR, MR) have important roles in the mechanisms regulating the activity of the hypothalamo-hypophyseal- adrenocortical system (HHAS), neuron survival/death, learning, and memory. Imbalance in MR and GR contents lead to impairments of HHAS activity and can promote neuron damage/death in extreme conditions. The present study used a quantitative immunocytochemistry method to provide the first comparative analysis of the effects of different regimes of hypobaric hypoxia on the nature of GR and MR expression in the dorsal (CA1) and ventral (dentate gyrus) parts of the hippocampus in rats. The data obtained here showed that severely harmful hypoxia induces marked impairments to the expression of both GR and MR in CA1 and dental gyrus cells, which correlated with damage/death of a significant proportion of neurons in CA1 and dysregulation of the activity of the HHAS. Series of three and six sessions (but not one session) of preconditioning with moderate hypoxia preceding severe hypoxia prevented these impairments. © 2014 Springer Science+Business Media.