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Hamarneh SR, Murphy CA, Shih CW, Frontera W, Torriani M, Irazoqui JE, Makimura H. Relationship between serum IGF-1 and skeletal muscle IGF-1 mRNA expression to phosphocreatine recovery after exercise in obese men with reduced GH. J Clin Endocrinol Metab 2015; 100:617-25. [PMID: 25375982 PMCID: PMC4318910 DOI: 10.1210/jc.2014-2711] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
CONTEXT GH and IGF-1 are believed to be physiological regulators of skeletal muscle mitochondria. OBJECTIVE The objective of this study was to examine the relationship between GH/IGF-1 and skeletal muscle mitochondria in obese subjects with reduced GH secretion in more detail. DESIGN Fifteen abdominally obese men with reduced GH secretion were treated for 12 weeks with recombinant human GH. Subjects underwent (31)P-magnetic resonance spectroscopy to assess phosphocreatine (PCr) recovery as an in vivo measure of skeletal muscle mitochondrial function and percutaneous muscle biopsies to assess mRNA expression of IGF-1 and mitochondrial-related genes at baseline and 12 weeks. RESULTS At baseline, skeletal muscle IGF-1 mRNA expression was significantly associated with PCr recovery (r = 0.79; P = .01) and nuclear respiratory factor-1 (r = 0.87; P = .001), mitochondrial transcription factor A (r = 0.86; P = .001), peroxisome proliferator-activated receptor (PPAR)γ (r = 0.72; P = .02), and PPARα (r = 0.75; P = .01) mRNA expression, and trended to an association with PPARγ coactivator 1-α (r = 0.59; P = .07) mRNA expression. However, serum IGF-1 concentration was not associated with PCr recovery or any mitochondrial gene expression (all P > .10). Administration of recombinant human GH increased both serum IGF-1 (change, 218 ± 29 μg/L; P < .0001) and IGF-1 mRNA in muscle (fold change, 2.1 ± 0.3; P = .002). Increases in serum IGF-1 were associated with improvements in total body fat (r = -0.53; P = .04), trunk fat (r = -0.55; P = .03), and lean mass (r = 0.58; P = .02), but not with PCr recovery (P > .10). Conversely, increase in muscle IGF-1 mRNA was associated with improvements in PCr recovery (r = 0.74; P = .02), but not with body composition parameters (P > .10). CONCLUSION These data demonstrate a novel association of skeletal muscle mitochondria with muscle IGF-1 mRNA expression, but independent of serum IGF-1 concentrations.
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Affiliation(s)
- Sulaiman R Hamarneh
- Department of Surgery (S.R.H.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; Program in Nutritional Metabolism (C.A.M., C.W.S., H.M.), Massachusetts General Hospital, Boston, Massachusetts 02114; Harvard College (C.W.S.), Boston, Massachusetts 02138; Department of Physical Medicine and Rehabilitation (W.F.), Vanderbilt University Medical Center, Nashville, Tennessee 37212; Department of Physical Medicine and Rehabilitation (W.F.), Harvard Medical School/Spaulding Rehabilitation Hospital, Boston, Massachusetts 02114; Department of Physiology (W.F.), University of Puerto Rico School of Medicine, San Juan, Puerto Rico 00936; and Department of Radiology (M.T.), Laboratory of Comparative Immunology, Center for the Study of Inflammatory Bowel Disease (J.E.I.), and Neuroendocrine Unit (H.M.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
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Yuen KCJ, Chong LE, Riddle MC. Influence of glucocorticoids and growth hormone on insulin sensitivity in humans. Diabet Med 2013; 30:651-63. [PMID: 23510125 DOI: 10.1111/dme.12184] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/13/2013] [Indexed: 12/17/2022]
Abstract
The seminal concept proposed by Sir Harold Himsworth more than 75 years ago that a large number of patients with diabetes were 'insulin insensitive', now termed insulin resistance, has now expanded to include several endocrine syndromes, namely those of glucocorticoid excess, and growth hormone excess and deficiency. Synthetic glucocorticoids are increasingly used to treat a wide variety of chronic diseases, whereas the beneficial effects of recombinant growth hormone replacement therapy in children and adults with growth hormone deficiency have now been well-recognized for over 25 years. However, clinical and experimental studies have established that increased circulating levels of glucocorticoids and growth hormone can also lead to worsening of insulin resistance, glucose intolerance, overt diabetes mellitus and cardiovascular disease. Improved understanding of the physiological 24-h rhythmicity of glucocorticoid and growth hormone secretion and its influence on the dawn phenomenon and the Staub-Trauggot effect has therefore led to renewed interest in studies on the mechanisms of insulin resistance induced by exogenous administration of glucocorticoids and growth hormone in humans. In this review, we describe the physiological events that result from the presence of resistance to insulin action at the level of skeletal muscle, adipose tissue, and liver, describe the known mechanisms of glucocorticoid- and growth hormone-mediated insulin resistance, and provide an update of the contributions of glucocorticoids and growth hormone to understanding the pathophysiology of insulin resistance and its effects on several endocrine syndromes.
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Affiliation(s)
- K C J Yuen
- Department of Medicine, Division of Endocrinology, Diabetes and Clinical Nutrition, Oregon Health and Science University, Portland, OR, USA.
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Krusenstjerna-Hafstrøm T, Clasen BF, Møller N, Jessen N, Pedersen SB, Christiansen JS, Jørgensen JOL. Growth hormone (GH)-induced insulin resistance is rapidly reversible: an experimental study in GH-deficient adults. J Clin Endocrinol Metab 2011; 96:2548-57. [PMID: 21613350 DOI: 10.1210/jc.2011-0273] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT It is clinically relevant and of physiological interest to investigate whether GH-induced insulin resistance depends on the timing of GH exposure relative to when insulin sensitivity is assessed. HYPOTHESIS GH-induced insulin resistance is rapidly reversible. DESIGN AND PARTICIPANTS Eight male GH-deficient patients underwent a 6-h euglycemic-hyperinsulinemic glucose clamp thrice in a randomized crossover design receiving either no GH (study 0), a 7-h GH infusion (0.2-0.3 mg in total) that terminated 5 h before the clamp (study 1), or a similar GH infusion timed to continue during the first hour of the clamp (study 2). A muscle biopsy was obtained 30 min into the clamp. The patients were compared with eight healthy untreated control subjects (study c). MAIN OUTCOME MEASURES The glucose infusion rate, indirect calorimetry, and free fatty acid metabolism were assessed. In muscle biopsies, protein phosphorylation of signal transducer and activator of transcription 5, Akt, and Akt substrate 160 (phospho-Akt substrate signal) and gene expression of IGF-I and SOCS1-3 were assessed. RESULTS Insulin sensitivity differed significantly between the GH-deficiency studies (P = 0.005) with distinct insulin resistance in study 2 and increased insulin sensitivity in study 0 [area under the glucose infusion rate curve (mg/kg · min): 1663 ± 151 (study 0) vs. 1482 ± 166 (study 1) vs. 1123 ± 136 (study 2) vs. 1492 ± 229 (control group)]. Free fatty acid levels and lipid oxidation were elevated in response to GH exposure but became suppressed during the clamp. IGF-I and SOCS3 gene expression was increased in study 2. CONCLUSIONS Very-low-dose GH exposure evokes acute insulin resistance that subsides after 5 h. This time-dependent reversibility should be considered when assessing the impact of GH on glucose homeostasis.
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Affiliation(s)
- T Krusenstjerna-Hafstrøm
- Department of Internal Medicine and Endocrinology and Medical Research Laboratories, Aarhus University Hospital, Denmark.
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Effects of GH in human muscle and fat. Pediatr Nephrol 2010; 25:705-9. [PMID: 19902270 DOI: 10.1007/s00467-009-1334-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 09/07/2009] [Accepted: 09/09/2009] [Indexed: 10/20/2022]
Abstract
Skeletal muscle is the major constituent of lean body mass and a major determinant of energy expenditure both at rest and during physical activity. Growth hormone, in turn, influences muscle mass as well as energy expenditure. Growth hormone substitution in adults increases muscle mass by 5-10%, but part of the effect is attributed to rehydration rather than protein accretion. In addition, GH regulates substrate metabolism in muscle and in particular antagonizes insulin-stimulated glucose disposal. This effect is linked to increased free fatty acid (FFA) flux but the molecular mechanisms remain unclear. During fasting, GH-induced insulin resistance may be favorable by reducing the demand of gluconeogenesis from protein. But in the postprandial phase, GH exposure may compromise glucose tolerance via the same mechanisms. Understanding the mechanisms whereby GH antagonizes insulin-stimulated glucose disposal in muscle is an important future research field with implications for a variety of clinical conditions ranging from malnutrition to obesity and type 2 diabetes.
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Widdowson WM, Healy ML, Sönksen PH, Gibney J. The physiology of growth hormone and sport. Growth Horm IGF Res 2009; 19:308-319. [PMID: 19505835 DOI: 10.1016/j.ghir.2009.04.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/03/2009] [Indexed: 11/20/2022]
Abstract
The growth hormone (GH)/ insulin-like growth factor-I (IGF-I) axis exerts short-and long-term metabolic effects that are potentially important during exercise. Exercise is a potent stimulus to GH release and there is some evidence that the acute increase in GH is important in regulating substrate metabolism post-exercise. Regular exercise also increases 24-hour GH secretion rates, which potentially contributes to the physiologic changes induced by training. The effects of GH replacement in GH-deficient adults provide a useful model with which to study the effects of the more long-term effects of the GH/ IGF-I axis. There is convincing evidence that GH replacement increases exercise capacity. Measures of exercise performance including maximal oxygen uptake (VO2max) and ventilatory threshold (VeT) are impaired in GH deficiency and improved by GH replacement, probably through some combination of increased oxygen delivery to exercising muscle, increased fatty acid availability with glycogen sparing, increased muscle strength, improved body composition and improved thermoregulation. Administration of supraphysiologic doses of GH to athletes increases fatty acid availability and reduces oxidative protein loss particularly during exercise, and increases lean body mass. It is not known whether these effects translate to improved athletic performance, although recombinant human GH is known to be widely abused in sport. The model of acromegaly provides evidence that long-term GH excess does not result in improved performance but it is possible that a "window" exists in which the protein anabolic effects of supraphysiologic GH might be advantageous.
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Affiliation(s)
- W Matthew Widdowson
- Department of Endocrinology and Diabetes, Adelaide and Meath Hospital, Tallaght, Dublin 24, Ireland
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Krag MB, Nielsen S, Guo Z, Pedersen SB, Schmitz O, Christiansen JS, Jørgensen JOL. Peroxisome proliferator-activated receptor gamma agonism modifies the effects of growth hormone on lipolysis and insulin sensitivity. Clin Endocrinol (Oxf) 2008; 69:452-61. [PMID: 18331610 DOI: 10.1111/j.1365-2265.2008.03231.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
CONTEXT Peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonists such as thiazolidinediones (TZDs) improve insulin sensitivity in type 2 diabetes mellitus (T2DM) through effects on fat metabolism whereas GH stimulates lipolysis and induces insulin resistance. OBJECTIVE To evaluate the impact of TZDs on fat metabolism and insulin sensitivity in subjects exposed to stable GH levels. DESIGN A randomized, placebo-controlled, double-blind parallel-group study including 20 GH-deficient patients on continued GH replacement therapy. The patients were studied before and after 12 weeks. INTERVENTION Patients received either pioglitazone 30 mg (N = 10) or placebo (N = 10) once daily for 12 weeks. RESULTS Adiponectin levels almost doubled during pioglitazone treatment (P = 0.0001). Pioglitazone significantly decreased basal free fatty acid (FFA) levels (P = 0.02) and lipid oxidation (P = 0.02). Basal glucose oxidation rate (P = 0.004) and insulin sensitivity (P = 0.03) improved in the patients who received pioglitazone treatment. The change in insulin-stimulated adiponectin level after pioglitazone treatment was positively correlated to the change in insulin-stimulated total glucose disposal (R = 0.69, P = 0.04). CONCLUSION The impact of GH on lipolysis and insulin sensitivity can be modified by administration of TZDs.
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Affiliation(s)
- Morten B Krag
- Medical Department M, Aarhus University Hospital, Aarhus Sygehus, Aarhus C, Denmark
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Trepp R, Flück M, Stettler C, Boesch C, Ith M, Kreis R, Hoppeler H, Howald H, Schmid JP, Diem P, Christ ER. Effect of GH on human skeletal muscle lipid metabolism in GH deficiency. Am J Physiol Endocrinol Metab 2008; 294:E1127-34. [PMID: 18413676 DOI: 10.1152/ajpendo.00010.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adult-onset growth hormone (GH) deficiency (GHD) is associated with insulin resistance and decreased exercise capacity. Intramyocellular lipids (IMCL) depend on training status, diet, and insulin sensitivity. Using magnetic resonance spectroscopy, we studied IMCL content following physical activity (IMCL-depleted) and high-fat diet (IMCL-repleted) in 15 patients with GHD before and after 4 mo of GH replacement therapy (GHRT) and in 11 healthy control subjects. Measurements of insulin resistance and exercise capacity were performed and skeletal muscle biopsies were carried out to assess expression of mRNA of key enzymes involved in skeletal muscle lipid metabolism by real-time PCR and ultrastructure by electron microscopy. Compared with control subjects, patients with GHD showed significantly higher difference between IMCL-depleted and IMCL-repleted. GHRT resulted in an increase in skeletal muscle mRNA expression of IGF-I, hormone-sensitive lipase, and a tendency for an increase in fatty acid binding protein-3. Electron microscopy examination did not reveal significant differences after GHRT. In conclusion, variation of IMCL may be increased in patients with GHD compared with healthy control subjects. Qualitative changes within the skeletal muscle (i.e., an increase in free fatty acids availability from systemic and/or local sources) may contribute to the increase in insulin resistance and possibly to the improvement of exercise capacity after GHRT. The upregulation of IGF-I mRNA suggests a paracrine/autocrine role of IGF-I on skeletal muscle.
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Affiliation(s)
- Roman Trepp
- Division of Endocrinology, Diabetology and Clinical Nutrition, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
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Abstract
The syndrome of adult GH deficiency and the effects of GH replacement therapy provide a useful model with which to study the effects of the GH/IGF-I axis on exercise physiology. Measures of exercise performance including maximal oxygen uptake and ventilatory threshold are impaired in adult GH deficiency and improved by GH replacement, probably through some combination of increased oxygen delivery to exercising muscle, increased fatty acid availability with glycogen sparing, increased muscle strength, improved body composition, and improved thermoregulation. In normal subjects, in addition to the long-term effects of GH/IGF-I status, there is evidence that the acute GH response to exercise is important in regulating substrate metabolism after exercise. Administration of supraphysiological doses of GH to athletes increases fatty acid availability and reduces oxidative protein loss, particularly during exercise, and increases lean body mass. Despite a lack of evidence that these metabolic effects translate to improved performance, GH abuse by athletes is widespread. Tests to detect GH abuse have been developed based on measurement in serum of 1) indirect markers of GH action, and 2) the relative proportions of the two major naturally occurring isoforms (20 and 22kDa) of GH. There is evidence that exercise performance and strength are improved by administration of GH and testosterone in combination to elderly subjects. The potential benefits of GH in these situations must be weighed against potential adverse effects.
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Affiliation(s)
- James Gibney
- Department of Endocrinology and Diabetes, Adelaide and Mental Hospital, Tallaght, Dublin 24, Ireland
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Landi F, Russo A, Capoluongo E, Cesari M, Liperoti R, Danese P, Bernabei R, Onder G. Insulin-like growth factor-binding protein 3 and hemoglobin concentration in older persons living in the community. Int J Hematol 2007; 85:294-9. [PMID: 17483071 DOI: 10.1532/ijh97.e0629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A decreased hemoglobin concentration is a common clinical condition in elderly subjects, and in at least 20% of the cases it is not possible to directly attribute the anemia to specific factors. The aim of the present study was to evaluate the relationship of different levels of insulin-like growth factor-binding protein 3 (IGFBP-3) with the blood concentration of hemoglobin in persons aged 80 years and older. Data are from a baseline evaluation of the Aging and Longevity in the Sirente Geographic Area (ilSIRENTE) study (n=253). Analysis of covariance was used to examine the effect of different IGFBP-3 levels on hemoglobin concentration. After adjustment for potential confounding variables, which included age, sex, number of diseases, renal failure, cancer, gastric ulcer, albumin, and iron concentrations, individuals in the group with higher IGFBP-3 concentrations showed a significantly higher mean hemoglobin concentration than participants in the group with lower IGFBP-3 concentrations (13.4 +/- 1.4 g/dL versus 12.9 +/- 1.9 g/dL, respectively; P=.03). In conclusion, the present study has shown that a higher IGFBP-3 level is associated with a higher hemoglobin concentration among older people living in the community. This finding suggests that the growth hormone/IGF axis may play an important role in hematopoiesis, and it may be implicated in the age-related decline in hemoglobin concentration.
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Affiliation(s)
- Francesco Landi
- Department of Gerontology and Geriatrics, Catholic University of Sacred Heart, Roma, Italy.
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Hansen M, Morthorst R, Larsson B, Flyvbjerg A, Rasmussen MH, Orskov H, Astrup A, Kjaer M, Lange KHW. Effects of 2 wk of GH administration on 24-h indirect calorimetry in young, healthy, lean men. Am J Physiol Endocrinol Metab 2005; 289:E1030-8. [PMID: 16046455 DOI: 10.1152/ajpendo.00124.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed as a randomized, double-blind placebo (Plc)-controlled study to determine the effect of 2 wk of growth hormone administration (GH-adm.) on energy expenditure (EE) and substrate oxidation in healthy humans. Sixteen young healthy men were divided into two groups. The study consisted of two 24-h measurements (indirect calorimetry), separated by 2 wk of either Plc or GH injections (6 IU/day). At baseline, no significant differences were observed between the two groups in any of the measured anthropometric, hormonal, or metabolic parameters, neither did the parameters change over time in the Plc group. GH-adm. resulted in a 4.4% increase in 24-h EE (P < 0.05) and an increase in fat oxidation by 29% (P < 0.05). However, a decrease in the respiratory quotient was only observed in the postabsorptive phase after an overnight fast (0.84 +/- 0.1 to 0.79 +/- 0.1, P < 0.05). Furthermore, lean body mass (LBM) was increased by GH-adm. only [62.8 +/- 2.5 kg (baseline) vs. 64.7 +/- 2.4 kg (after), P < 0.001]. In conclusion, GH-adm. increases 24-h EE, which may be partly explained by increased LBM. Furthermore, GH-adm. stimulates fat combustion, especially in the postabsorptive state.
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Affiliation(s)
- Mette Hansen
- Institute of Sports Medicine, Copenhagen, Building 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark.
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Hansen M, Morthorst R, Larsson B, Dall R, Flyvbjerg A, Rasmussen MH, Orskov H, Kjaer M, Lange KHW. No effect of growth hormone administration on substrate oxidation during exercise in young, lean men. J Physiol 2005; 567:1035-45. [PMID: 16002451 PMCID: PMC1474222 DOI: 10.1113/jphysiol.2005.089524] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The purpose of this study was to examine the effects of increased fat availability induced by growth hormone (GH) administration on the oxidative metabolism during exercise. Seven well-trained males (age 25 +/- 2 years (mean +/- S.E.M.); peak oxygen consumption : 62 +/- 1 ml min(-1) kg(-1) (completed four randomised trials: 120 min bicycling at 55% 4 h after receiving either 7.5 IU (2.5 mg) GH or placebo (Plc), and during rest after receiving either GH or Plc. In all studies a standardized meal was given 2 h after GH or Plc injection. GH administration resulted in an approximately 60-fold increase in serum GH concentration at rest (P < 0.0001) and during exercise (P < 0.0001). The increase in serum GH was followed by an increase in circulating glycerol at rest (8%, P < 0.0001). When combined with exercise the increase in plasma glycerol was more pronounced (GH: 716% of baseline versus Plc: 328%, P < 0.0001). However, this increase in fat mobilization did not increase fat oxidation during exercise (indirect calorimetry). In conclusion, GH administration combined with aerobic exercise increased lipolytic parameters substantially more than exercise alone, but did not further augment whole body fat oxidation.
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Affiliation(s)
- Mette Hansen
- Institute of Sports Medicine, Copenhagen, Denmark.
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Jørgensen JOL, Krag M, Jessen N, Nørrelund H, Vestergaard ET, Møller N, Christiansen JS. Growth hormone and glucose homeostasis. HORMONE RESEARCH 2005; 62 Suppl 3:51-5. [PMID: 15539799 DOI: 10.1159/000080499] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Patients with active acromegaly are insulin-resistant and glucose-intolerant, whereas children with growth hormone (GH) deficiency (GHD) are insulin-sensitive and may develop fasting hypoglycaemia. Surprisingly, however, hypopituitary adults with unsubstituted GHD tend to be insulin-resistant, which may worsen during GH substitution. During fasting, which may be considered the natural domain for the metabolic effects of GH, the induction of insulin resistance by GH is associated with enhanced lipid oxidation and protein conservation. In this particular context, insulin resistance appears to constitute a favourable metabolic adaptation. The problem is that GH substitution results in elevated circadian GH levels in non-fasting patients. The best way to address this challenge is to employ evening administration of GH and to tailor the dose. Insulin therapy may cause hypoglycaemia and GH substitution may cause hyperglycaemia. Such untoward effects should be minimized by carefully monitoring the individual patient.
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Affiliation(s)
- Jens O L Jørgensen
- Medical Department M (Endocrinology and Diabetes) and Institute of Experimental Clinical Research, Arhus University Hospital, Arhus, Denmark.
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Jørgensen JOL, Nørrelund H, Conceicao F, Møller N, Christiansen JS. Somatropin and glucose homeostasis: considerations for patient management. ACTA ACUST UNITED AC 2005; 1:229-34. [PMID: 15799216 DOI: 10.2165/00024677-200201040-00004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
More than 60 years ago it was shown, in dogs, that anterior pituitary extracts may cause glucose intolerance and that hypophysectomy was associated with increased insulin sensitivity. Accordingly, active acromegaly is characterized by insulin resistance at the hepatic and muscular level, whereas children with growth hormone (GH) deficiency are insulin hypersensitive and prone to developing fasting hypoglycemia. Somewhat unexpectedly, hypopituitary adults with untreated GH deficiency tend to be insulin resistant, which may be aggravated by somatropin (GH) therapy. The explanation for this apparent paradox has not been fully established. It is, however, likely that high circulating levels of free fatty acids (FFA) are responsible for insulin resistance, both before and after somatropin therapy. In the untreated state, patients have abdominal obesity, which increases circulating FFA levels. Since GH has potent lipolytic effects, somatropin therapy will further increase FFA levels. Theoretically, this GH replacement effect will eventually be compensated for by favorable alterations in body composition, including a reduction of fat mass. Subcutaneous somatropin therapy, however, will cause some degree of hypersomatropinemia in the prandial phase, which will inevitably antagonize the physiologic effects of insulin. At present, the best way to circumvent this inherent problem is to employ evening injections of somatropin and to ensure that the dosage is not too high. In the latter regard, it is important to realize that dosage requirements are lower in adults compared with children, and that the dosage will probably need to be reduced with age in the individual patient.
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Affiliation(s)
- Jens O L Jørgensen
- Medical Department M (Endocrinology and Diabetes), Institute of Experimental Clinical Research, Aarhus University Hospital, Aarhus, Denmark.
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Johansen T, Laurino C, Barreca A, Malmlöf K. Reduction of adiposity with prolonged growth hormone treatment in old obese rats: effects on glucose handling and early insulin signaling. Growth Horm IGF Res 2005; 15:55-63. [PMID: 15701573 DOI: 10.1016/j.ghir.2004.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 11/19/2004] [Accepted: 11/22/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVES Growth Hormone (GH) promotes loss of body fat and causes insulin resistance. It is debated whether reduction of body fat mass during long term growth hormone (GH) administration improves carbohydrate metabolism. To answer this question we assessed carbohydrate handling and tissue specific function of the insulin receptor (IR) and insulin receptor substrate-1 (IRS-1) during prolonged GH treatment of obese rats. METHODS Body fat % estimated by DEXA scanning, plasma IGF-I, glucose and insulin were studied in 17 months old dietary induced obese rats treated for 4, 21 or 41 days (GH: 4 mg/kg/d or saline total n=90). Adipose tissue, muscle and liver samples were obtained after 21 days and expression and tyrosine phosphorylation of IR and IRS-1 proteins and the degree of IRS-1-Janus Kinase-2 (JAK2) interaction were analyzed by immunoprecipitation and immunoblotting. RESULTS Forty-one days GH treatment caused the body fat to decline significantly to 20+/-3% (Mean+/-SEM), whereas it remained steady on 51+/-4% in the pair fed group. Insulin levels in response to OGTT were significantly elevated throughout the experiment. IR amount was elevated in adipose tissue but decreased in liver after GH treatment while IR phosphorylation was increased in muscle only. IRS-1 amount was elevated in adipose tissue and muscle while IRS-1 phosphorylation was increased only in liver. The association of IRS-1 with JAK-2 was increased in liver and muscle. CONCLUSIONS An extensive reduction of fat mass did not improved signs of insulin resistance in GH treated old obese rats. The molecular events associated with GH treatment included tissue specific changes in the function of IR and IRS-1 suggesting the liver to be the primary site of insulin resistance. Furthermore, the association of IRS-1with JAK-2 in the course of GH signaling could present a mechanism for GH to directly induce insulin resistance.
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Affiliation(s)
- T Johansen
- Department of Pharmacological Research, Discovery, Novo Nordisk, DK-2760 Måløv, Denmark.
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Affiliation(s)
- Jens Møller
- Medical Department, Aarhus Kommunehospital, Institute of Clinical Experimental Research, University of Aarhus, DK-8000 Aarhus C., Denmark.
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Affiliation(s)
- G Johannsson
- RCEM, Sahlgrenska University Hospital, Göteborg, Sweden
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Vann RC, Nguyen HV, Reeds PJ, Steele NC, Deaver DR, Davis TA. Somatotropin increases protein balance independent of insulin's effects on protein metabolism in growing pigs. Am J Physiol Endocrinol Metab 2000; 279:E1-E10. [PMID: 10893316 DOI: 10.1152/ajpendo.2000.279.1.e1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Somatotropin (ST) administration enhances protein deposition and elicits profound metabolic responses, including hyperinsulinemia. To determine whether the anabolic effect of ST is due to hyperinsulinemia, pair-fed weight-matched growing swine were treated with porcine ST (150 microg x kg body wt(-1) x day(-1)) or diluent for 7 days (n = 6/group, approximately 20 kg). Then pancreatic glucose-amino acid clamps were performed after an overnight fast. The objective was to reproduce the insulin levels of 1) fasted control and ST pigs (basal insulin, 5 microU/ml), 2) fed control pigs (low insulin, 20 microU/ml), and 3) fed ST pigs (high insulin, 50 microU/ml). Amino acid and glucose disposal rates were determined from the infusion rates necessary to maintain preclamp blood levels of these substrates. Whole body nonoxidative leucine disposal (NOLD), leucine appearance (R(a)), and leucine oxidation were determined with primed, continuous infusions of [(13)C]leucine and [(14)C]bicarbonate. ST treatment was associated with higher NOLD and protein balance and lower leucine oxidation and amino acid and glucose disposals. Insulin lowered R(a) and increased leucine oxidation, protein balance, and amino acid and glucose disposals. These effects of insulin were suppressed by ST treatment; however, the protein balance remained higher in ST pigs. The results show that ST treatment inhibits insulin's effects on protein metabolism and indicate that the stimulation of protein deposition by ST treatment is not mediated by insulin. Comparison of the protein metabolic responses to ST treatment during the basal fasting period with those in the fully fed state from a previous study suggests that the mechanism by which ST treatment enhances protein deposition is influenced by feeding status.
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Affiliation(s)
- R C Vann
- United States Department of Agriculture, Agricultural Research Service (USDA/ARS) Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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19
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Abstract
A growth-promoting principle of the pituitary gland was discovered in 1921, and bovine growth hormone (GH) was isolated in 1944. Since then, the structure of GH as it relates to its biological activities has been an exciting research topic. Equally fascinating is the relationship between GH structure and its metabolic activities. In attempts to define some of these activities, several investigators have used GH transgenic mice as models. In this review we summarize what is known about the molecular mechanisms of GH action. We then describe some of the GH transgenic models and point out potential targets for nutrition research.
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Affiliation(s)
- J J Kopchick
- Edison Biotechnology Institute, Konneker Research Laboratories, College of Osteopathic Medicine, Ohio University, Athens 45701, USA.
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Roemmich JN, Clark PA, Mai V, Berr SS, Weltman A, Veldhuis JD, Rogol AD. Alterations in growth and body composition during puberty: III. Influence of maturation, gender, body composition, fat distribution, aerobic fitness, and energy expenditure on nocturnal growth hormone release. J Clin Endocrinol Metab 1998; 83:1440-7. [PMID: 9589636 DOI: 10.1210/jcem.83.5.4760] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We examined the relationships among gender, sexual maturation, four-compartment model estimates of body composition, body fat distribution (magnetic resonance imaging for abdominal visceral fat and anthropometrics), aerobic fitness, basal and total energy expenditure, and overnight GH release in an ultrasensitive chemiluminescence assay in healthy prepubertal and pubertal boys (n = 18 and 11, respectively) and girls (n = 12 and 18, respectively). Blood samples were withdrawn every 10 min from 1800-0600 h to determine the area under the serum GH-time curve (AUC), sum of the GH peak heights (sigma GH peak heights), and the mean nadir GH concentration. GH release was greater in the pubertal than prepubertal subjects due to an increase in sigma GH peak heights (43.8 +/- 3.6 vs. 24.1 +/- 3.5 ng.mL-1, P = 0.0002) and mean nadir (1.7 +/- 0.2 vs. 0.7 +/- 0.2 ng.mL-1, P = 0.0002), but not peak number (4.3 +/- 0.2 vs. 4.5 +/- 0.2). The girls had a greater sigma GH peak heights (39.0 +/- 3.5 vs. 28.8 +/- 3.6 ng.mL-1, P = 0.05) and mean nadir concentration (1.4 +/- 0.2 vs. 0.9 +/- 0.2 ng.mL-1, P = 0.05) than the boys. Significant inverse relationships existed between sigma GH peak heights (r = -0.35, P = 0.06) or mean nadir (r = -0.39, P = 0.04) and four-compartment percent body fat for all boys but not for all girls or when combining all subjects. For all girls, significant inverse relationships existed between sigma GH peak heights (r = -0.39, P = 0.03) or mean nadir (r = -0.37, P = 0.04) and waist/hip ratio. Similar inverse relationships in all boys or all subjects were not significant. Forward stepwise regression analysis determined that bone age (i.e. maturation, primary factor) and gender were the significant predictors of AUC, sigma GH peak heights, and mean nadir. The influence of maturation reflects rising sex steroid concentrations, and the gender differences appear to be because of differences in estradiol concentrations rather than to body composition or body fat distribution.
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Affiliation(s)
- J N Roemmich
- University of Virginia Health Sciences Center, Department of Pediatrics, Charlottesville 22908, USA.
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Monti LD, Brambilla P, Caumo A, Magni F, Omati S, Nizzoli G, di Natale B, Galli-Kienle M, Cobelli C, Chiumello G, Pozza G. Glucose turnover and insulin clearance after growth hormone treatment in girls with Turner's syndrome. Metabolism 1997; 46:1482-8. [PMID: 9439548 DOI: 10.1016/s0026-0495(97)90153-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The study was performed to elucidate, by means of a euglycemic-hyperinsulinemic clamp, whether insulin sensitivity, lipid levels, posthepatic insulin delivery, and insulin clearance are impaired in girls with Turner's syndrome in the absence of previous treatment (T0) and after 6 (T6) and 12 (T12) months of growth hormone (GH) therapy (GHT). The study was performed in six girls with Turner's syndrome and eight healthy girls. We found that previously untreated girls with Turner's syndrome had a normal insulin activity on glucose metabolism. GHT progressively and significantly decreased hepatic insulin sensitivity. In fact, residual hepatic glucose release (HGR), which was 19.6 +/- 4.7 mg/m2. min at T0, doubled at T6 (39.3 +/- 5.1 mg/m2.min) and showed a threefold increase at T12 (68.7 +/- 10.8 mg/m2.min, P < .05 v T0). On the contrary, GHT did not show an appreciable influence on peripheral insulin sensitivity. Insulin clearance was higher in girls with Turner's syndrome than in control girls at T0 (30.0 +/- 2.8 v 20.2 +/- 1.1 mL.kg-1.min-1). It decreased to normal values at T6 (18.2 +/- 2.0 mL.kg-1.min-1, P < .05 v T0) and remained at normal levels at T12 (23.8 +/- 2.9 mL.kg-1. min-1). The posthepatic insulin delivery rate significantly increased at T6 and T12, suggesting increased insulin secretion. In conclusion, we found that insulin-stimulated glucose turnover was normal in girls with Turner's syndrome before therapy. One year of GHT was successful in stimulating the growth rate, but significantly decreased the insulin suppressibility on HGR with only slight changes in peripheral insulin sensitivity. In addition, an increase in the insulin posthepatic delivery rate and a normalization of insulin clearance were present, probably to counteract hepatic insulin resistance.
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Affiliation(s)
- L D Monti
- Istituto Scientifico H. San Raffaele, Cattedra di Clinica Medica, Milano, Italy
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McNurlan MA, Garlick PJ, Steigbigel RT, DeCristofaro KA, Frost RA, Lang CH, Johnson RW, Santasier AM, Cabahug CJ, Fuhrer J, Gelato MC. Responsiveness of muscle protein synthesis to growth hormone administration in HIV-infected individuals declines with severity of disease. J Clin Invest 1997; 100:2125-32. [PMID: 9329979 PMCID: PMC508405 DOI: 10.1172/jci119747] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This study was undertaken to determine if human recombinant growth hormone (hrGH, 6 mg/d for 2 wk) would stimulate muscle protein synthesis in AIDS wasting. Healthy controls were compared with patients who were HIV+, had AIDS without weight loss, and had AIDS with > 10% weight loss. Before hrGH, rates of skeletal muscle protein synthesis, measured with l-[2H5]phenylalanine, were the same in controls and in all stages of disease. Rates of myofibrillar protein degradation, however, assessed from urinary excretion of 3-methyl histidine, were higher in AIDS and AIDS wasting than in HIV+ or healthy individuals. The group with weight loss had significantly higher TNFalpha levels but not higher HIV viral loads. Muscle function, as determined by isokinetic knee extension and shoulder flexion, was significantly higher in controls than all infected individuals. After GH, rates of protein synthesis were stimulated 27% in controls, with a smaller increase (11%) in HIV+, and a significant depression (42%) in AIDS with weight loss, despite fourfold elevation in insulin-like growth factor-I in all groups. There was a significant correlation of hrGH-induced changes in muscle protein synthesis with severity of disease (P = 0.002). The results indicate increased basal muscle protein degradation and decreased responsiveness of muscle protein synthesis to GH in the later stages of disease.
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Affiliation(s)
- M A McNurlan
- Department of Surgery, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
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