Oxidative Stress Accompanies HIF1-Dependent Impairment of Glucose Metabolism in the Hippocampus of Adult Rats That Survived Prenatal Severe Hypoxia.

Abstract

Introduction: Many socially significant diseases are associated with prenatal developmental disorders. Previously, we showed the pathological role of hypoxia-inducible factor-1 (HIF1) in post-hypoxic reoxygenation. This study aimed to investigate the effect of prenatal severe hypoxia (PSH) on HIF1α protein expression as well as on HIF1-dependent activity of the pentose phosphate pathway (PPP) and anaerobic glycolysis in the hippocampus (HPC) of offspring that reached adulthood.

Methods: PSH was induced during the critical period of fetal hippocampal formation on gestation days 14-16 in a hypobaric chamber (180 Torr, 5% oxygen, 3 h). Subsequent studies were conducted on both the HPC of adult control and PSH rats under normal conditions, as well as in response to severe hypoxia (SH) or psycho-emotional stress ("learned helplessness" [LH] model). We evaluated HIF1α protein levels using both immunohistochemistry and Western blotting techniques. The amount of glucose-6-phosphate dehydrogenase (G6PD) was also determined by Western blotting. Colorimetric enzymatic assays were employed to analyze enzymatic activity of lactate dehydrogenase (LDH), the concentration of lactate, NADPH, reduced glutathione (GSHred), and malonic dialdehyde (MDA).

Results: We showed that PSH caused a stable increase in the content of HIF1α protein in the HPC, which was accompanied by an increase in the efficiency of anaerobic glycolysis. This was confirmed by increased LDH activity and lactate concentration. At the same time, the amounts of G6PD, NADPH, and GSHred decreased in the HPC of PSH rats, whereas the concentration of MDA, an oxidative stress marker, exceeded the control values. In a series of experiments using the LH or SH stress, it was shown that in the HPC of control rats, there was an increase in the amount of HIF1α in response to stress, which was also accompanied by more efficient anaerobic glycolysis and decrease of PPP-dependent NADPH production, similar to the intact PSH rats. In PSH rats, emotional stress resulted in higher HIF1α levels without affecting glycolysis or PPP.

Conclusion: Therefore, the increased content and activity of the transcription factor HIF1α in the HPC of adult rats exposed to prenatal hypoxia leads to an imbalance between glycolysis and PPP, which is accompanied by oxidative stress.