Thioredoxin-1 expression levels in rat hippocampal neurons in moderate hypobaric hypoxia

• Published in: Neuroscience and behavioral physiology 2009, Vol.39 (1), p.1-5
• Main Authors: Stroev, S. A., Tyul’kova, E. I., Glushchenko, T. S., Tugoi, I. A., Samoilov, M. O., Pelto-Huikko, M.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - physiology; Animals; Antioxidants; Behavioral Sciences; Biomedical and Life Sciences; Biomedicine; Hippocampus - metabolism; Hypoxia; Hypoxia - metabolism; Ischemia; Male; Neurobiology; Neurons; Neurons - metabolism; Neurosciences; Physiology; Proteins; Rats; Rats, Wistar; Reactive Oxygen Species - metabolism; Thioredoxins - biosynthesis
• ISSN: 0097-0549; 1573-899X
• DOI: 10.1007/s11055-008-9091-5

Previous studies have demonstrated that preconditioning (PC) with three sessions of moderate hypoxia significantly increases the expression of the antioxidant protein thioredoxin-1 (Trx-1) in the rat hippocampus by 3 h after subsequent acute severe hypoxia as compared with non-preconditioned animals. However, it remained unclear whether this increase in Trx-1 accumulation during PC is induced before severe hypoxia or is a modification of the response to severe hypoxia. This question was addressed in the present investigation using experiments on 12 adult male Wistar rats with studies of Trx-1 expression after PC without subsequent severe hypoxia. Immunocytochemical studies were performed 3 and 24 h after three episodes of moderate hypobaric hypoxia (three sessions of 2 h at 360 mmHg with 24-h intervals). Immunoreactivity to Trx-1 24 h after the last session was significantly decreased in neurons in all the areas of the hippocampus studied (CA1, CA2, CA3, and the dentate gyrus). Immunoreactivity in CA3 was also decreased 3 h after hypoxia. These results provide evidence that moderate preconditioning hypoxia itself not only does not increase, but even significantly decreases Trx-1 expression. Thus, increases in Trx-1 contents in the hippocampus of preconditioned animals after severe hypoxia are not associated with the accumulation of this protein during PC, but with a PC-induced modification of the reaction to severe hypoxia.