Multiple Mild Hypobaric Hypoxia Induces Expression of Thioredoxin-1 in the Hippocampus and Neocortex of Rats

Abstract

It is known that mild hypobaric hypoxia preconditioning may prevent brain damage induced by ischemic stroke and other forms of hypoxia. Activation of the antioxidant systems is one of the key molecular mechanisms that protect cells from oxidative stress during and after severe hypoxia/ischemia. Specifically, the cytoplasmic protein antioxidant thioredoxin-1 efficiently protects neurons from oxidative stress and hypoxia-induced damage. It has been previously shown that preconditioning with triple mild hypobaric hypoxia treatment significantly increased the expression of some endogenous antioxidants, including thioredoxin- 1, in the rat brain after subsequent severe hypoxia. This increase correlated with prevention or at least substantial amelioration of behavioral disturbances and structural brain damage. However, triple preconditioning per se, that is, without or prior to beginning of the subsequent severe hypoxia, did not increase but even significantly decreased the expression of thioredoxin-1 and some other antioxidants. In the present study we estimated the effects of a six-time mild hypobaric hypoxia on the expression of thioredoxin-1 in various regions of the hippocampus and neocortex of rats. Using immunocytochemistry, we demonstrate that six-time treatment with mild hypoxia significantly increases the thioredoxin-1 expression in neurons of the hippocampus and neocortex of rats 24 h after the last hypoxia treatment.