Glucocorticoid receptor mRNA expression in peripheral blood mononuclear cells in high trained compared to low trained athletes and untrained subjects
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Background: Physiological needs during prolonged exercise are a potent stimulus for the hypothalamic-pituitaryadrenal (HPA) axis. Hence, athletes undergoing daily endurance training sessions may have frequent and prolonged phases of endogenous hypercortisolism. Since chronic glucocorticoids treatment leads to down-regulation of glucocorticoid receptor α (GR-α) mRNA expression, endurance training could lead to modulation of GR expression. Aim: The aim of the study was to evaluate GR-α and GR-β mRNA expressions in peripheral blood mononuclear cells and plasma cortisol, ACTH and cortisol binding globulin (CBG) concentrations at rest in subjects undergoing different training regimes. Subjects and methods: Nine high trained (HT) swimmers (training volume: 21.6±1.7 hours/week in 10–12 sessions) were compared with two age-matched control groups represented by 8 low trained (LT) runners (training volume: 6.4±2.6 h/week in 3–5 sessions) and 9 untrained subjects. Expression of GR was determined by RT-PCR of total RNA. Hormone levels were determined by radioimmunoassay methods. Results: HT athletes showed 10 times less GR-a mRNA expression than the untrained subjects, while LT athletes exhibited values about twofold less than the untrained subjects. GR-β mRNA expression was undetectable in all subjects. No differences were observed among the three groups in hormone levels. Conclusions: GR-a mRNA expression is repressed in proportion to the amount and frequency of the stressful stimuli due to training. Hence, this down-regulation may be a consequence of the frequent and prolonged exposure to cortisol acute elevations induced by training. GR-β did not play an important role in inducing the down-regulation of GR-a mRNA expression observed.
KeywordsCortisol exercise GR-α mRNA expression GR-β mRNA expression swimming
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- 1.Galbo H. Hormonal and metabolic adaptation to exercise. Stuttgart, Georg Thieme Verlag 1983, 46–51.Google Scholar
- 5.Orth DN, Kovaks WJ. The adrenal cortex. In: Williams RH, Foster DW, Kronenberg HM, Larsen PR, Wilson JD eds. Williams Textbook of Endocrinology. 9th ed. Philadelphia: WB Saunders. 1998, 517–664.Google Scholar
- 11.Webster JC, Oakley RH, Jewell CM, Cidlowski JA. Proinflammatory cytokines regulate human glucocorticoid receptor gene expression and lead to the accumulation of the dominant negative beta isoform: a mechanism for the generation of glucocorticoid resistance. Proc Natl Acad Sci U S A 2001, 98: 6865–70.PubMedCentralPubMedCrossRefGoogle Scholar
- 17.Boyum A. Isolation of mononuclear cells and granulocytes from human blood. Isolation of monuclear cells by one centrifugation, and of granulocytes by combining centrifugation and sedimentation at 1 g. Scand J Clin Lab Invest 1968, 97: 77–89.Google Scholar