Acclimatization to Middle Attitude Hypoxia Masks the Symptoms of Experimental Posttraumatic Stress Disorder, but Does Not Affect Its Pathogenetic Mechanisms.

The effects of acclimatization to middle attitude hypoxia on the resistance to acute emotional stress were studied on the model of posttraumatic stress disorder in rats. Anxyolitic, but not anxiogenic effect was observed in acclimatized rats. However, acclimatized rats with posttraumatic stress disorder were characterized by hypofunction of the pituitary-adrenocortical axis, which is typical of this pathology, and reduction in corticosterone/dehydroepiandrosterone ratio. At the neuroendocrine level, up-regulation of glucocorticoid receptors and a decrease in the level of corticotropin-releasing hormone in the hippocampus were revealed. The observed modifications of regulatory mechanisms can underlie hypofunction of the pituitary-adrenocortical axis. It was concluded that acclimatization to middle attitude hypoxia masks behavioral symptoms of posttraumatic stress disorder, but does not alter its pathogenetic neuroendocrine mechanisms.