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Prolonged Physical Training Decreases mRNA Levels of Glucocorticoid Receptor and Inflammatory Genes

Background/Aims: Prolonged physical exercise induces adaptive alterations in the hypothalamic-pituitary axis, increasing cortisol metabolism, and reducing cortisol synthesis and glucocorticoid sensitivity. The mechanisms responsible for this relative glucocorticoid resistance remain unknown but may involve expression of genes encoding glucocorticoid receptor (GR) and/or inflammatory molecules of nuclear factor kappa B1 (NFkB1) signaling pathway and cytokines. This study aimed to determine the impact of prolonged physical training on the expression of genes involved in glucocorticoid action and inflammatory response. Methods: Normal sedentary male cadets of the Brazilian Air Force Academy were submitted to 6 weeks of standardized physical training. Eighteen of 29 initially selected cadets were able to fully complete the training program. Fasting glucose, insulin and cortisol levels, cytokine concentration and the expression of genes encoding GR, NFkB1, inhibitor of NFkB1 and IkB kinase A were determined before and after the training period. Results: Prolonged physical exercise reduced the basal cortisol levels and the percent cortisol reduction after dexamethasone. These findings were associated with a significant reduction in the mRNA levels of GR (6.3%), NFkB1 (63%), inhibitor of NFkB1 (25%) and IkB kinase A (46%) with concomitant reduction in cytokine concentrations (ELISA). Conclusions: Prolonged physical training decreases the glucocorticoid sensitivity and the mRNA levels of the GR gene combined with decreased mRNA of genes related to the NFkB pathway.

Aspectos moleculares da sensibilidade aos glicocorticóides

Glucocorticoids play an essential role in maintaining basal and stress-related homeostasis. Most known effects of glucocorticoids are mediated by the intracellular glucocorticoid receptors. The glucocorticoid sensitivity seems to depend on the amount of receptors expressed and the efficiency of glucocorticoid receptor-mediated signal transduction. Glucocorticoid resistance or hypersensitivity, seen in autoimmune-inflammatory diseases and in metabolic syndrome respectively, can represent the variability of several steps that influence the signaling cascade of glucocorticoid action. The recognition of these steps could provide the understanding of the clinical phenotype and course of such diseases as well as their responsiveness to glucocorticoid therapy. The comprehension of these pathophysiological mechanisms can also improve the possible therapeutic interventions. In this review, we have summarized the multiple factors that have been shown to be involved in this signaling cascade and, thus, to influence glucocorticoid sensitivity.

Antiproliferative and apoptotic potencies of glucocorticoids: nonconcordance with their antiinflammatory and immunossuppressive properties

Relative antiinflammatory and immunosuppressive potencies of glucocorticoids (GC) were previously well defined. Nonetheless, GC also regulate cell proliferation and programmed death (apoptosis). The aim of this study was to determine the relative potency of different GC on the modulation of cell survival. The GC-sensitive lymphoblast cell line CEM-c7/14 was submitted to 48 h-exposure to GC (dose-response curve from 10(-8) to 10(-5) M). Cell survival was analyzed employing the DimethylTiazol-Tetrazolium (MTT) test. For each GC at least 4 experiments were performed in quadruplicate. Responses to different GC at the same molarity were analyzed by ANOVA on Ranks. Cell responses to the same GC in different concentrations were tested by repeated measures ANOVA. The EC50 for each GC was calculated with the GraphPad Prism 3.0 software. The use of low concentrations (10(-8) and 10(-7) M) of hydrocortisone and methylprednisolone determined a similar effects on cell survival, which was less prominent than that observed with betamethasone, budesonide or momethasone. Momethasone was the most potent GC, inducing the most intense dexamethasone reduction on cell survival at the lowest concentration (10(-8) M). Momethasone and methylprednisolone were the two GC with the strongest impact on cell survival. Our findings suggest that antiproliferative and apoptotic potencies of GC are different from those previously reported antiinflammatory and immunosuppressive actions.

A very low dose intravenous dexamethasone suppression test as an index of glucocorticoid sensitivity.

Background/Aims: The wide variability of responses to corticotherapy suggests a role for individual recognition of steroid sensitivity in order to customize treatment. Oral dexamethasone (DEX) administration may be hindered by the rate of its intestinal absorption and the liver first-passage effect. In this study we suggest that an intravenous very low dose DEX suppression test (VLD IV-DST) can be used as an index for glucocorticoid (GC) sensitivity. Methods: We evaluated 87 normal subjects: 44 prepubertal children, 23 adolescents and 20 adults with a VLD IV-DST using 20 µg/m2 of DEX (dose able to recognize GC sensitivity). Cortisol was initially measured at several time-points after DEX prompting us to establish its nadir and subsequent simplification of the test by measuring cortisol at baseline and after 120 min. Results: Baseline cortisol was similar in adolescents and in adults, but lower in children. There was a spectrum of individual responses in all age groups. The percent reduction of cortisol after 120 min was different in these three age groups, with median values of 44.4% in children, 25.9% in adolescents and 61.6% in adults. Conclusion: This simplified VLD IV-DST using 20 µg/m2 of DEX is useful to evaluate individual sensitivity to GC in different age groups.

Evaluation of Glucocorticoid Sensitivity and Its Potential Clinical Applicability

Glucocorticoids (GC) play an important role in physiologic and pathophysiologic adaptive responses to stress. The majority of these effects are mediated by the GC receptors (GR). GC sensitivity largely depends of the amount of available GR, and their ability to bind the GC-responsive element and/or other nuclear transcription factors, leading to modulation of the expression of GC target genes. Clinical conditions of tissue-specific GC resistance or GC hypersensitivity have been described in several diseases, such as chronic inflammatory and autoimmune conditions, and in visceral obesity, such as metabolic syndrome. Several in vivo and in vitro methods have been described, allowing the evaluation and quantitation of GC sensitivity. The recognition of these parameters has improved our comprehension of the mechanisms involved in those diseases, with potential implications for the diagnosis and therapy of such abnormalities.

First Two Years’ Response to Growth Hormone Treatment in Very Young Preterm Small for Gestational Age Children

Background: Growth hormone (GH) is a therapeutic option for small for gestational age (SGA) children without spontaneous catch-up. There are few reports on preterm SGA children. Prematurity is an additional risk factor for adult short stature. Aim: To describe GH efficacy in preterm SGA patients. Methods: Twenty-five preterm SGA patients, 2–4 years old, treated with GH 0.066 mg/kg/day, were compared with 14 age-matched preterm SGA historical controls. Height, weight, IGF-I, IGFBP-3, fasting glucose and insulin were measured every 6 months. Results: At start of GH treatment, mean height and weight were –2.4 and –2.4 SDS, respectively. There was a significant increment in height SDS of 1.3 and 2.1 during the 1st and the 2nd year of GH therapy, respectively. There was no significant difference between the progression of chronological and bone ages. A significant increase in IGF-I, IGFBP-3 and molar ratio was observed during GH therapy. There was no difference in glucose, insulin or HOMA-IR index. Conclusion: We showed for the first time that the height increment of preterm SGA with GH treatment is similar to that described in other studies with term SGA patients. Therefore, short-term GH treatment in a subset of preterm SGA patients between 2–4 years of age was able to promote adequate growth recovery with no excessive bone age acceleration or adverse effects on carbohydrate metabolism.

Impact of prolonged physical training on the pituitary glucocorticoid sensitivity determined by very low dose intravenous dexamethasone suppression test.

The activity of the hypothalamic-pituitary-adrenal axis is usually modulated by several stress factors, including exercise. Different responses are induced by physical training according to duration and intensity of exercise. During prolonged training, cortisol remains normal or decreased as a consequence of altered cortisol secretion, metabolism and excretion, and possibly by changes in glucocorticoid sensitivity. The aim of this study was to evaluate the impact of prolonged physical training on the glucocorticoid sensitivity. Eighteen cadets of the Air Force Academy, mean (SD) age: 18.7 (1.0) years, underwent an intensive 6-week preparatory training-period considered adequate by inducing significant changes on body composition measured by bioelectrical impedance. Measurement of individuals pituitary glucocorticoid sensitivity was done by an intravenous very low dose dexamethasone suppression test (20 microg/m (2)) that was performed before and after the training period. Cortisol levels were obtained at basal condition and 120 minutes after the dexamethasone infusion. Basal cortisol showed a significant decrease after prolonged training. The percent cortisol suppression after dexamethasone tended to be lower after the training period. Overall, our data suggest that prolonged physical training is able to reduce glucocorticoid sensitivity, which can have a beneficial impact in chronic stress conditions.

Applicability of real-time PCR methodology in the neonatal detection of Turner syndrome.

Turner syndrome (TS) is the complete or partial loss of the second sex chromosome, occurring in 1:5 000 girls. Early recognition allows appropriate therapy for short stature and puberty. Neonatal diagnosis of TS permits detection of associated malformations, minimizing sequels. Aiming to develop a molecular method for the diagnosis of TS we employed blood samples stored on filter paper. We evaluated 78 female controls, 25 TS girls with 45,X karyotype, and 32 TS patients with other karyotypes. After DNA extraction, samples were submitted to real-time PCR, using primers and probes directed to the study gene ARSE and to the control gene GAPDH. A ROC curve established the ARSE:GAPDH ratio with a cutoff value of 0.7. Low ARSE:GAPDH ratio of <0.7 was present in 100% of 45,X TS patients. This cutoff value presented a sensitivity of 100% and a specificity of 100% in detecting 45,X TS patients with a positive predictive value of 100% and a negative predictive value of 100%. The same cutoff value was able to identify only 56% of TS with other karyotypes, in which we observed a mean (SD) ARSE:GAPDH ratio=0.66 (0.2); and the interquartile range=0.4-0.8. Determination of ARSE:GAPDH ratio is a fast, sensitive, and specific method, with viable cost and feasible automation, which makes it potentially applicable in neonatal screening programs for the diagnosis of Turner syndrome 45,X.

Simultaneous evaluation of in vivo glucocorticoid sensitivity and expression of glucocorticoid receptor alpha-isoform in rheumatoid arthritis patients

OBJECTIVES To analyze glucocorticoid (GC) sensitivity using intravenous very low dose dexamethasone suppression test (IV-VLD-DST) in patients with rheumatoid arthritis (RA) and its correlation with glucocorticoid receptor alpha-isoform (GRalpha) gene expression. METHODS We evaluated 20 healthy controls and 32 RA patients with Health Assessment Questionnaire (HAQ) and Disease Activity Score 28 joints (DAS) scores and IV-VLD-DST and GRalpha expression in mononuclear cells. RESULTS Basal cortisol and the percentage of cortisol reduction after IV-VLD-DST were lower in RA patients than in controls, whereas GRalpha expression was similar among groups. In the RA group there was an inverse correlation between GRalpha expression and the percentage of cortisol suppression that was not observed in controls. There was a direct relationship between DAS and GRalpha expression. CONCLUSIONS Mechanisms involved in GC resistance observed in patients with RA are possibly not at the level of GRalpha gene expression, since it was similar among groups and GRalpha increased with disease activity.

TSH neurosecretory dysfunction (TSH-nd) in Down syndrome (DS): low risk of progression to Hashimoto's thyroiditis

INTRODUCTION Patients with Down syndrome (DS) often have elevated TSH (hypothalamic origin), which is called TSH neurosecretory dysfunction (TSH-nd). In these cases, there is slight elevation in TSH (5-15 µUI/mL), with normal free T4 and negative thyroid antibodies (AB). OBJECTIVE To recognize the risk of progression to Hashimotos thyroiditis (HT). SUBJECTS AND METHODS We retrospectively analyzed 40 DS patients (mean age = 4.5 years), followed up for 6.8 years. RESULTS HT was diagnosed in 9/40 patients, three early in monitoring, and six during evolution. In 31/40 patients, TSH-nd diagnosis remained unchanged over the years, with maximum TSH values ranging from 5 to 15 µUI/mL. In this group, free T4 also remained normal and AB were negative. There was a significant TSH reduction (p = 0.017), and normal TSH concentrations (< 5.0 µUI/mL) were observed in 29/31 patients, in at least one moment. No patient had TSH > 15 µUI/mL. CONCLUSION DS patients with TSH-nd present low risk of progression to HT (10% for females and 6% for males).