title: Thioredoxin-1 expression levels in rat hippocampal neurons in moderate hypobaric hypoxia.
abstract: 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.
authors.affiliation: Department of Developmental Biology, University Medical School, Tampere, Finland.
authors.forename: S A
authors.initials: SA
authors.lastname: Stroev
authors.forename: E I
authors.initials: EI
authors.lastname: Tyul'kova
authors.forename: T S
authors.initials: TS
authors.lastname: Glushchenko
authors.forename: I A
authors.initials: IA
authors.lastname: Tugoi
authors.forename: M O
authors.initials: MO
authors.lastname: Samoilov
authors.forename: M
authors.initials: M
authors.lastname: Pelto-Huikko
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D006624:Hippocampus / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D013879:Thioredoxins / Q000096:biosynthesis*
chemical_list: D017382:Reactive Oxygen Species; C495697:Txn1 protein, rat; D013879:Thioredoxins