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Lewitt MS. The Role of the Growth Hormone/Insulin-Like Growth Factor System in Visceral Adiposity. BIOCHEMISTRY INSIGHTS 2017; 10:1178626417703995. [PMID: 28469442 PMCID: PMC5404904 DOI: 10.1177/1178626417703995] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 03/19/2017] [Indexed: 12/18/2022]
Abstract
There is substantial evidence that the growth hormone (GH)/insulin-like growth factor (IGF) system is involved in the pathophysiology of obesity. Both GH and IGF-I have direct effects on adipocyte proliferation and differentiation, and this system is involved in the cross-talk between adipose tissue, liver, and pituitary. Transgenic animal models have been of importance in identifying mechanisms underlying these interactions. It emerges that this system has key roles in visceral adiposity, and there is a rationale for targeting this system in the treatment of visceral obesity associated with GH deficiency, metabolic syndrome, and lipodystrophies. This evidence is reviewed, gaps in knowledge are highlighted, and recommendations are made for future research.
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Affiliation(s)
- Moira S Lewitt
- School of Health, Nursing & Midwifery, University of the West of Scotland, Paisley, UK
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Veldhuis JD, Dyer RB, Trushin SA, Bondar OP, Singh RJ, Klee GG. Interleukins 6 and 8 and abdominal fat depots are distinct correlates of lipid moieties in healthy pre- and postmenopausal women. Endocrine 2016; 54:671-680. [PMID: 27444747 PMCID: PMC5107333 DOI: 10.1007/s12020-016-1041-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 06/27/2016] [Indexed: 01/24/2023]
Abstract
UNLABELLED Available data associate lipids concentrations in men with body mass index, anabolic steroids, age, and certain cytokines. Data were less clear in women, especially across the full adult lifespan, and when segmented by premenopausal and postmenopausal status. SUBJECTS 120 healthy women (60 premenopausal and 60 postmenopausal) in Olmsted County, MN, USA, a stable well studied clinical population. Dependent variables: measurements of 10 h fasting high-density lipoprotein cholesterol, total cholesterol, low-density lipoprotein cholesterol, and triglycerides. INDEPENDENT VARIABLES testosterone, estrone, estradiol, 5-alpha-dihydrotestosterone, and sex-hormone binding globulin (by mass spectrometry); insulin, glucose, and albumin; abdominal visceral, subcutaneous, and total abdominal fat [abdominal visceral fat, subcutaneous fat, total abdominal fat by computerized tomography scan]; and a panel of cytokines (by enzyme-linked immunosorbent assay). Multivariate forward-selection linear-regression analysis was applied constrained to P < 0.01. Lifetime data: High-density lipoprotein cholesterol was correlated jointly with age (P < 0.0001, positively), abdominal visceral fat (P < 0.0001, negatively), and interleukin-6 (0.0063, negatively), together explaining 28.1 % of its variance (P = 2.3 × 10-8). Total cholesterol was associated positively with multivariate age only (P = 6.9 × 10-4, 9.3 % of variance). Triglycerides correlated weakly with sex-hormone binding globulin (P = 0.0115), and strongly with abdominal visceral fat (P < 0.0001), and interleukin-6 (P = 0.0016) all positively (P = 1.6 × 10-12, 38.9 % of variance). Non high-density lipoprotein cholesterol and low-density lipoprotein cholesterol correlated positively with both total abdominal fat and interleukin-8 (P = 2.0 × 10-5, 16.9 % of variance; and P = 0.0031, 9.4 % of variance, respectively). Premenopausal vs. postmenopausal comparisons identified specific relationships that were stronger in premenopausal than postmenopausal individuals, and vice versa. Age was a stronger correlate of low-density lipoprotein cholesterol; interleukin-6 of triglycerides and high-density lipoprotein; and both sex-hormone binding globulin and total abdominal fat of non high-density lipoprotein cholesterol in premenopausal than postmenopausal women. Conversely, sex-hormone binding globulin, abdominal visceral fat, interleukin-8, adiponectin were stronger correlates of triglycerides; abdominal visceral fat, and testosterone of high-density lipoprotein cholesterol; and age of both non high-density lipoprotein and low-density lipoprotein in postmenopausal than premenopausal women. Our data delineate correlations of total abdominal fat and interleukin-8 (both positively) with non high-density lipoprotein cholesterol and low-density lipoprotein cholesterol in healthy women across the full age range of 21-79 years along with even more specific associations in premenopausal and postmenopausal individuals. Whether some of these outcomes reflect causal relationships would require longitudinal and interventional or genetic studies.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Roy B Dyer
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
| | - Sergey A Trushin
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
- Department of Neurology, 200 First Street SW, Rochester, MN, 55905, USA
| | - Olga P Bondar
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
| | - Ravinder J Singh
- Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - George G Klee
- Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
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Musumeci G, Castorina S, Castrogiovanni P, Loreto C, Leonardi R, Aiello FC, Magro G, Imbesi R. A journey through the pituitary gland: Development, structure and function, with emphasis on embryo-foetal and later development. Acta Histochem 2015; 117:355-66. [PMID: 25858531 DOI: 10.1016/j.acthis.2015.02.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 12/28/2014] [Accepted: 02/05/2015] [Indexed: 12/22/2022]
Abstract
The pituitary gland and the hypothalamus are morphologically and functionally associated in the endocrine and neuroendocrine control of other endocrine glands. They therefore play a key role in a number of regulatory feedback processes that co-ordinate the whole endocrine system. Here we review the neuroendocrine system, from the discoveries that led to its identification to some recently clarified embryological, functional, and morphological aspects. In particular we review the pituitary gland and the main notions related to its development, organization, cell differentiation, and vascularization. Given the crucial importance of the factors controlling neuroendocrine system development to understand parvocellular neuron function and the aetiology of the congenital disorders related to hypothalamic-pituitary axis dysfunction, we also provide an overview of the molecular and genetic studies that have advanced our knowledge in the field. Through the action of the hypothalamus, the pituitary gland is involved in the control of a broad range of key aspects of our lives: the review focuses on the hypothalamic-pituitary-gonadal axis, particularly GnRH, whose abnormal secretion is associated with clinical conditions involving delayed or absent puberty and reproductive dysfunction.
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Veldhuis JD, Dyer RB, Trushin SA, Bondar OP, Singh RJ, Klee GG. Immunologic and mass-spectrometric estimates of SHBG concentrations in healthy women. Metabolism 2014; 63:783-92. [PMID: 24746136 PMCID: PMC4066221 DOI: 10.1016/j.metabol.2014.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/07/2014] [Accepted: 03/17/2014] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Sex-hormone binding globulin (SHBG) concentrations across the adult female lifespan are not well defined. To address this knowledge gap, SHBG was quantified by both immunological and criterion methods, viz, mass spectrometry (MS). SETTING Center for Translational Science Activities (CTSA). PARTICIPANTS Healthy nonpregnant women (N=120) ages 21 to 79 years. OUTCOMES SHBG, testosterone (T), estradiol (E2) and estrone (E1) each determined by MS. Uni- and multivariate regression of SHBG concentrations on age, body mass index (BMI), total and visceral abdominal fat (TAF, AVF), albumin, glucose, insulin, sex steroids, selected cytokines, blood pressure, and lipids. RESULTS By univariate regression, MS-estimated SHBG correlated negatively with BMI, TAF, AVF, insulin, free T and bioavailable T (bio T) (each P≤10(-4)), but not with blood pressure or lipids. By stepwise multivariate regression analysis, free and total T (both positive) and bio T (negative) were correlated with SHBG in all 4 assays (each P<10(-15), R(2)≥0.481). In addition, TAF and BMI were negatively associated with SHBG (P≤0.0066) in 2 SHBG assays, and estrone and IL-8 with SHBG weakly (P≤0.035) in one SHBG assay each. When nonsignificant cytokines were excluded, SHBG was jointly associated with AVF, total T and HDL (P<10(-9), R(2)=0.358). CONCLUSION According to MS, three metabolic factors, T, AVF and HDL, together explain more than one-third of the interindividual variation in SHBG levels. We speculate that these measures reflect insulin action.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Mayo Clinic, Rochester, MN 55905.
| | - Roy B Dyer
- Immunochemical Laboratory, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Sergey A Trushin
- Immunochemical Laboratory, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905; Department of Neurology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Olga P Bondar
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Ravinder J Singh
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - George G Klee
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
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Veldhuis JD, Bondar OP, Dyer RB, Trushin SA, Klee EW, Singh RJ, Klee GG. Immunological and mass spectrometric assays of SHBG: consistent and inconsistent metabolic associations in healthy men. J Clin Endocrinol Metab 2014; 99:184-93. [PMID: 24203061 PMCID: PMC3879680 DOI: 10.1210/jc.2013-2642] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT SHBG concentrations correlate inconsistently with metabolic parameters. HYPOTHESIS SHBG assay platforms contribute to nonuniformities according to the literature. DESIGN The design of the study was a noninterventional quantification of SHBG by two immuno- and two mass spectrometric assays and abdominal visceral fat by computed tomography scan. SETTING The study was conducted at the Center for Translational Science Activities. PARTICIPANTS Healthy men (n=120) aged 18-80 years with a body mass index of 20-43 kg/m2 participated I the study. OUTCOMES Outcomes of the study included a correlation of log SHBG with age, metabolic surrogates [body mass index, albumin, glucose, insulin, abdominal (total and visceral) fat, homeostasis model assessment insulin resistance index], sex steroids (estrone, 17β-estradiol, T, and dihydrotestosterone by mass spectrometry), and adipocytokines (IL-1β, IL-6, IL-8, IL-10 and IL-12, TNF-α, and adiponectin). RESULTS By univariate regression, age (P<10(-4)), dihydrotestosterone (P<10(-4)), T (P≤.00022), and adiponectin (P≤.0084) were positive correlates, and insulin and homeostasis model assessment insulin resistance index were negative correlates (P≤.0060) of SHBG in all four assays. Stepwise multivariate analysis unveiled that age and T together could explain 38.1%-52.5% of the statistical variance in SHBG in all assays (P<10(-11)). Multivariate regression without sex steroids unveiled that age (P<10(-5)) and insulin (P<10(-3)) are jointly associated with SHBG levels in the four assays with overall R2=0.215-0.293 and P<10(-6). In one immunological SHBG assay each, abdominal visceral fat and adiponectin were weak multivariates also. CONCLUSION Immunological and mass spectrometric SHBG assays yield both consistent and inconsistent correlations with key metabolic variables in healthy men, thereby potentially explaining earlier inconsistencies in the literature.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit (J.D.V.), Mayo School of Graduate Medical Education Center for Translational Science Activities, Immunochemical Laboratory (R.B.D.), and Departments of Neurology (S.A.T.) and Laboratory Medicine and Pathology (J.D.V., O.P.B., E.W.K., R.J.S., G.G.K.), Mayo Clinic, Rochester, Minnesota 55905
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Abstract
Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.
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Affiliation(s)
- André Tchernof
- Endocrinology and Genomics Axis, Centre Hospitalier Universitaire de Québec, Québec, Canada
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Le Tissier PR, Hodson DJ, Lafont C, Fontanaud P, Schaeffer M, Mollard P. Anterior pituitary cell networks. Front Neuroendocrinol 2012; 33:252-66. [PMID: 22981652 DOI: 10.1016/j.yfrne.2012.08.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 08/17/2012] [Accepted: 08/18/2012] [Indexed: 12/17/2022]
Abstract
Both endocrine and non-endocrine cells of the pituitary gland are organized into structural and functional networks which are formed during embryonic development but which may be modified throughout life. Structural mapping of the various endocrine cell types has highlighted the existence of distinct network motifs and relationships with the vasculature which may relate to temporal differences in their output. Functional characterization of the network activity of growth hormone and prolactin cells has revealed a role for cell organization in gene regulation, the plasticity of pituitary hormone output and remarkably the ability to memorize altered demand. As such, the description of these endocrine cell networks alters the concept of the pituitary from a gland which simply responds to external regulation to that of an oscillator which may memorize information and constantly adapt its coordinated networks' responses to the flow of hypothalamic inputs.
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Affiliation(s)
- P R Le Tissier
- Division of Molecular Neuroendocrinology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom;
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Iranmanesh A, Lawson D, Veldhuis JD. Distinct metabolic surrogates predict basal and rebound GH secretion after glucose ingestion in men. J Clin Endocrinol Metab 2012; 97:2172-9. [PMID: 22472562 PMCID: PMC3387415 DOI: 10.1210/jc.2011-3317] [Citation(s) in RCA: 9] [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: 12/26/2022]
Abstract
CONTEXT GH secretion declines rapidly after glucose ingestion and then recovers to higher-than-baseline levels (rebound GH release). HYPOTHESIS Selective metabolic markers predict the magnitude of glucose-suppressed GH release and postglucose rebound-like GH secretion. DESIGN Prospectively randomized crossover study of GH secretion after glucose vs. water ingestion. SETTING The study was conducted at a clinical translational research center. PARTICIPANTS Sixty-nine healthy men aged 19-78 yr with a body mass index of 18-39 kg/m(2) participated in the study. OUTCOMES OUTCOMES included nadir vs. peak GH concentrations and basal vs. pulsatile GH secretion. RESULTS Mean nadir GH concentrations were determined positively by sex hormone binding globulin (SHBG) after glucose administration (R(2) = 0.088, P = 0.0077). Peak rebound GH concentrations were related positively to adiponectin and negatively to computed tomography-estimated abdominal visceral fat (AVF) (R(2) = 0.182, P = 0.00049) after glucose ingestion. Deconvolution analysis showed that SHBG specifically predicted basal (nonpulsatile) GH secretion after glucose exposure (R(2) = 0.153, P = 0.00052). In contrast, together exercise history and adiponectin (both positively) and AVF (negatively) predicted pulsatile GH escape after glucose suppression (R(2) = 0.206, P = 0.00043). Moreover, adiponectin uniquely determined the size (mass), and AVF the mode (duration), of GH secretory bursts after glucose exposure (both P < 0.006). CONCLUSION Glucose ingestion provides a clinical model for investigating complementary metabolic surrogates that determine suppression and recovery of basal and pulsatile GH secretion in healthy men.
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Affiliation(s)
- Ali Iranmanesh
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Center for Translational Science Activities, Mayo Clinic, Rochester, Minnesota 55905, USA
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Zirilli L, Orlando G, Carli F, Madeo B, Cocchi S, Diazzi C, Carani C, Guaraldi G, Rochira V. GH response to GHRH plus arginine is impaired in lipoatrophic women with human immunodeficiency virus compared with controls. Eur J Endocrinol 2012; 166:415-24. [PMID: 22189998 DOI: 10.1530/eje-11-0829] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE GH secretion is impaired in lipodystrophic human immunodeficiency virus (HIV) patients and inversely related to lipodystrophy-related fat redistribution in men. Less is known about the underlying mechanisms involved in reduced GH secretion in HIV-infected women. DESIGN A case-control, cross-sectional study comparing GH/IGF1 status, body composition, and metabolic parameters in 92 nonobese women with HIV-related lipodystrophy and 63 healthy controls matched for age, ethnicity, sex, and body mass index (BMI). METHODS GH, IGF1, IGF binding protein 3 (IGFBP3), GH after GHRH plus arginine (GHRH+Arg), several metabolic variables, and body composition were evaluated. RESULTS GH response to GHRH+Arg was lower in HIV-infected females than in controls. Using a cutoff of peak GH ≤ 7.5 μg/l, 20.6% of HIV-infected females demonstrated reduced peak GH response after GHRH+Arg. In contrast, none of the control subjects demonstrated a peak GH response ≤ 7.5 μg/l. Bone mineral density (BMD), quality of life, IGF1, and IGFBP3 were lowest in the HIV-infected females with a GH peak ≤ 7.5 μg/l. BMI was the main predictive factor of GH peak in stepwise multiregression analysis followed by age, with a less significant effect of visceral fat in the HIV-infected females. CONCLUSIONS This study establishes that i) GH response to GHRH+Arg is lower in lipoatrophic HIV-infected women than in healthy matched controls, ii) BMI more than visceral adipose tissue or trunk fat influences GH peak in this population, and iii) HIV-infected women with a GH peak below or equal to 7.5 μg/l demonstrate reduced IGF1, IGFBP3, BMD, and quality of life.
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Affiliation(s)
- Lucia Zirilli
- Integrated Department of Medicine, University of Modena and Reggio Emilia, Via Giardini 1355, 41100 Modena, Italy
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Iranmanesh A, Bowers CY, Veldhuis JD. Secretagogue type, sex-steroid milieu, and abdominal visceral adiposity individually determine secretagogue-stimulated cortisol secretion. Eur J Endocrinol 2010; 162:1043-9. [PMID: 20299490 PMCID: PMC3108036 DOI: 10.1530/eje-10-0149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
DESIGN While androgens and estrogens control glucocorticoid secretion in animal models, how the sex-steroid milieu determines cortisol secretion in humans is less clear. To address this issue, cortisol was measured in archival sera obtained at 10-min intervals for 5 h in 42 healthy men administered double placebo, placebo and testosterone, testosterone and dutasteride (to block 5alpha-reductases type I and type II), or testosterone and anastrozole (to block aromatase) in a double-blind, placebo-controlled, prospectively randomized design. METHODS Subjects received i.v. injection of saline, GHRH, GH-releasing peptide-2 (GHRP-2), somatostatin (SS), and GHRP-2/GHRH/l-arginine (triple stimulus) each on separate mornings fasting. Outcomes comprised cortisol concentrations, pulsatile cortisol secretion, and relationships with age or abdominal visceral fat (AVF). RESULTS By ANCOVA, baseline (saline-infused) cortisol concentrations (nmol/l) did not differ among the sex-steroid milieus (overall mean 364+/-14). In contrast, stimulated peak cortisol concentrations were strongly determined by secretagogue type (P<0.001) as follows: triple stimulus (868+/-27)>GHRP-2 (616+/-42)>saline=SS=GHRH (grand mean 420+/-21). After GHRP-2 injection, pulsatile cortisol secretion increased with age (R(2)=0.16, P=0.012). After the triple stimulus, pulsatile cortisol secretion correlated i) inversely with serum 5alpha-dihydrotestosterone (DHT) concentrations (R(2)=0.53, P=0.026) and ii) directly with computerized tomography-estimated AVF (R(2)=0.11, P=0.038). CONCLUSION Age, DHT concentrations, AVF, and secretagogue type influence pulsatile cortisol secretion at least in men. Further studies should be performed to assess ACTH secretion and native ghrelin action in defined sex-steroid milieus.
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Affiliation(s)
- Ali Iranmanesh
- Endocrine Section, Department of Medicine, Salem Veterans Affairs Medical Center, Salem, VA 24153
| | - Cyril Y. Bowers
- Endocrine Division, Department of Medicine, Tulane University Health Science Center, New Orleans, LA 70112
| | - Johannes D. Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Research Center, Mayo Clinic, Rochester, MN 55905
- Corresponding author: Tel: 507-255-0902, Fax: 507-255-0901,
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Redman LM, Veldhuis JD, Rood J, Smith SR, Williamson D, Ravussin E. The effect of caloric restriction interventions on growth hormone secretion in nonobese men and women. Aging Cell 2010; 9:32-9. [PMID: 19878147 DOI: 10.1111/j.1474-9726.2009.00530.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Lifespan in rodents is prolonged by caloric restriction (CR) and by mutations affecting the somatotropic axis. It is not known if CR can alter the age-associated decline in growth hormone (GH), insulin-like growth factor (IGF)-1 and GH secretion. To evaluate the effect of CR on GH secretory dynamics; forty-three young (36.8 +/- 1.0 years), overweight (BMI 27.8 +/- 0.7) men (n = 20) and women (n = 23) were randomized into four groups; control = 100% of energy requirements; CR = 25% caloric restriction; CR + EX = 12.5% CR + 12.5% increase in energy expenditure by structured exercise; LCD = low calorie diet until 15% weight reduction followed by weight maintenance. At baseline and after 6 months, body composition (DXA), abdominal visceral fat (CT) 11 h GH secretion (blood sampling every 10 min for 11 h; 21:00-08:00 hours) and deconvolution analysis were measured. After 6 months, weight (control: -1 +/- 1%, CR: -10 +/- 1%, CR + EX: -10 +/- 1%, LCD: -14 +/- 1%), fat mass (control: -2 +/- 3%, CR: -24 +/- 3%, CR + EX: -25 +/- 3%, LCD: -31 +/- 2%) and visceral fat (control: -2 +/- 4%, CR: -28 +/- 4%, CR + EX: -27 +/- 3%, LCD: -36 +/- 2%) were significantly (P < 0.001) reduced in the three intervention groups compared to control. Mean 11 h GH concentrations were not changed in CR or control but increased in CR + EX (P < 0.0001) and LCD (P < 0.0001) because of increased secretory burst mass (CR + EX: 34 +/- 13%, LCD: 27 +/- 22%, P < 0.05) and amplitude (CR + EX: 34 +/- 14%, LCD: 30 +/- 20%, P < 0.05) but not to changes in secretory burst frequency or GH half-life. Fasting ghrelin was significantly increased from baseline in all three intervention groups; however, total IGF-1 concentrations were increased only in CR + EX (10 +/- 7%, P < 0.05) and LCD (19 +/- 4%, P < 0.001). A 25% CR diet for 6 months does not change GH, GH secretion or IGF-1 in nonobese men and women.
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Affiliation(s)
- Leanne M Redman
- Pennington Biomedical Research Center, Baton Rouge, LA, USA.
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Gan EH, Quinton R. Physiological Significance of the Rhythmic Secretion of Hypothalamic and Pituitary Hormones. PROGRESS IN BRAIN RESEARCH 2010; 181:111-26. [DOI: 10.1016/s0079-6123(08)81007-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Hudson SB, Schroeder DR, Bailey JN, Mielke KL, Erickson D, Miles JM, Bowers CY, Veldhuis JD. Pre- versus postmenopausal age, estradiol, and peptide-secretagogue type determine pulsatile growth hormone secretion in healthy women: studies using submaximal agonist drive and an estrogen clamp. J Clin Endocrinol Metab 2010; 95:353-60. [PMID: 19858315 PMCID: PMC2805499 DOI: 10.1210/jc.2009-1769] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT GH-releasing peptide (GHRP), GHRH, and somatostatin are physiological regulators of pulsatile GH secretion. HYPOTHESIS Age, independently of abdominal visceral fat (AVF) and basal (nonpulsatile) GH secretion, damps pulsatile GH secretion driven by physiological (rather than pharmacological) amounts of GHRP and GHRH in an experimentally controlled estradiol (E(2)) milieu. DESIGN AND SETTING A prospectively randomized, double-blind parallel-cohort study was conducted at an academic medical center. PARTICIPANTS Community-dwelling healthy premenopausal (PRE, age 24 +/- 0.8 yr, n = 20) and postmenopausal (POST, age 63 +/- 1.8 yr, n = 22) women participated in the study. INTERVENTIONS Gonadal-axis down-regulation with leuprolide was followed by randomized addback of placebo or transdermal E(2) and separate-day iv bolus injections of a half-maximally stimulatory dose of GHRP-2 or GHRH (each 0.33 mug/kg). ANALYSIS Three-way analysis of covariance included main factors age, E(2) status, and secretagogue type and covariates AVF and basal GH secretion. RESULTS Submaximally stimulated pulsatile GH secretion was positively determined by PRE vs. POST age (P < 0.001), E(2) repletion vs. depletion (P = 0.001) and GHRP-2 vs. GHRH stimulation (P < 0.001), after adjustment for AVF and basal secretion. E(2) vs. placebo elevated fasting mean GH concentrations in both PRE and POST women (P = 0.006) but increased basal (nonpulsatile) GH secretion in PRE only (P = 0.002). PRE vs. POST age prolonged GHRH-driven GH secretory bursts by 36% (P = 0.006). CONCLUSION PRE vs. POST age, E(2) availability, and physiological peptide drive are triple determinants of pulsatile GH secretion independently of abdominal visceral fat and nonpulsatile GH secretion in healthy women.
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Affiliation(s)
- Susan B Hudson
- Department of Obstetrics and Gynecology, Mayo School of Graduate Medical Education, Clinical Translational Research Center, Mayo Clinic, Rochester, Minnesota 55905
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Veldhuis JD, Hudson SA, Bailey JN, Erickson D. Regulation of basal, pulsatile, and entropic (patterned) modes of GH secretion in a putatively low-somatostatin milieu in women. Am J Physiol Endocrinol Metab 2009; 297:E483-9. [PMID: 19491298 PMCID: PMC2724111 DOI: 10.1152/ajpendo.00136.2009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Somatostatin (SS) released by hypothalamic neurons inhibits GH exocytosis noncompetitively. Therefore, we postulated that attenuation of GH feedback-induced SS outflow would help to unmask covariates of endogenous secretagogue drive. To this end, 42 healthy pre- and postmenopausal women were randomly assigned to receive leuprolide plus estradiol (E(2)) or leuprolide plus placebo. A putatively low-SS milieu was imposed by L-arginine infusion. Deconvolution and regularity analyses were applied to 6-h GH concentration-time profiles. By two-way ANOVA, age negatively (P < 0.001) and E(2) positively (P = 0.001) determined pulsatile GH secretion in the presumptively SS-deficient milieu (P < 0.001). Comparable effects were exerted on the mass of GH secreted per burst per unit distribution volume (age P = 0.001, E(2) P < 0.001, overall P < 0.001). E(2) alone predicted basal (nonpulsatile) GH secretion (P = 0.004). Stepwise forward-selection multivariate regression demonstrated that age (P = 0.0017) and E(2) (P = 0.0002) together explained 46% of intersubject variability in pulsatile GH secretion (P < 0.001) and fully replaced the negative univariate effect of abdominal visceral fat (r(2) = 0.32, P < 0.001). Moreover, age and E(2) (but not AVF) interacted to supervise GH regularity (P = 0.007). We conclude that age and E(2) availability individually and together constitute primary predictors of basal, pulsatile, and patterned GH secretion in an inferentially feedback-silenced context in healthy women. Therefore, both factors must be considered in framing hypotheses of endogenous GH drive.
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Affiliation(s)
- Johannes D Veldhuis
- Departments of Internal Medicine, Mayo Medical and Graduate Schools of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Veldhuis JD, Keenan DM, Bailey JN, Miles JM, Bowers CY. Preservation of GHRH and GH-releasing peptide-2 efficacy in young men with experimentally induced hypogonadism. Eur J Endocrinol 2009; 161:293-300. [PMID: 19458139 PMCID: PMC2772823 DOI: 10.1530/eje-09-0270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Somatostatin (SS), GHRH, GH-releasing peptide (GHRP), and the sex-steroid milieu regulate GH secretion. OBJECTIVE To test whether GHRH and GHRP remain effective secretagogs in the face of short-term hypogonadism. DESIGN Prospective, randomized double-blind. METHODS Healthy young men (n=24) received a GnRH agonist twice 3 weeks apart followed by placebo (n=13, Pl) or testosterone (n=11, testosterone) addback. SUBJECTS were then given consecutive i.v. infusions of l-arginine (to restrain SS outflow) and a maximally effective dose of GHRH or GHRP-2 (to test corresponding secretagog pathways). RESULTS GH secretion stimulated by l-arginine/GHRH and by l-arginine/GHRP-2 was unaffected by combined testosterone/estradiol (E(2)) depletion. The low testosterone/E(2) milieu decreased basal (nonpulsatile) GH secretion (P=0.038), without altering fasting pulsatile GH secretion or IGF1 or IGF-binding protein (IGFBP)-3 concentrations. IGFBP-1 (P<0.0001) and abdominal visceral fat (AVF, P=0.017) correlated negatively with fasting basal GH secretion. By contrast, IGF1 (P=0.0012) and IGFBP-3 (P=0.015) correlated positively with fasting pulsatile GH secretion. AVF (P=0.0024) was a negative determinant, and IGF1 a positive determinant (P=0.018), of GHRH-driven GH pulses. Responses to GHRP-2 were unrelated to any of these factors. CONCLUSION l-arginine/GHRP-2 appears to be an especially robust stimulus of GH secretion, since efficacy is unmodified by profound short-term hypogonadism, a range of AVF estimates, and a spectrum of IGF1, IGFBP-1, and IGFBP-3 concentrations. Whether robustness also applies to chronic hypogonadism is not known.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Veldhuis JD, Hudson SB, Erickson D, Bailey JN, Reynolds GA, Bowers CY. Relative effects of estrogen, age, and visceral fat on pulsatile growth hormone secretion in healthy women. Am J Physiol Endocrinol Metab 2009; 297:E367-74. [PMID: 19470834 PMCID: PMC2724113 DOI: 10.1152/ajpendo.00230.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Growth hormone (GH) secretion is subject to complex regulation. How pre- and postmenopausal age (PRE, POST), estradiol (E(2)) availability, and abdominal visceral fat (AVF) jointly affect peptidyl-secretagogue drive of GH secretion is not known. To this end, healthy PRE (n = 20) and POST (n = 22) women underwent a low- vs. high-E(2) clamp before receiving a continuous intravenous infusion of GH-releasing hormone (GHRH) or GH-releasing peptide (GHRP-2). According to analysis of covariance, PRE and POST women achieved age-independent hypo- and euestrogenemia under respective low- and high-E(2) clamps. All four of age (P < 0.001), E(2) status (P = 0.006), secretagogue type (P < 0.001), and an age x peptide interaction (P = 0.014) controlled pulsatile GH secretion. Independently of E(2) status, POST women had lower GH responses to both GHRH (P = 0.028) and GHRP-2 (P < 0.001) than PRE women. Independently of age, GHRP-2 was more stimulatory than GHRH during low E(2) (P = 0.011) and high E(2) (P < 0.001). Stepwise forward-selection multivariate analysis revealed that computerized tomographic estimates of AVF explained 22% of the variability in GHRH action (P = 0.002), whereas age and E(2) together explained 60% of the variability in GHRP-2 drive (P < 0.001). These data establish that age, estrogen status, and AVF are triple covariates of continuous peptide-secretagogue drive of pulsatile GH secretion in women. Each factor must be controlled for to allow valid comparisons of GH-axis activity.
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Affiliation(s)
- Johannes D Veldhuis
- Departments of Internal Medicine, Endocrine Research Unit, Clinical Translational Research Unit, Mayo Medical and Graduate Schools of Medicine, Mayo Clinic, Rochester, Minnesota, USA.
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Veldhuis JD, Bowers CY. Factors other than sex steroids modulate GHRH and GHRP-2 efficacies in men: evaluation using a GnRH agonist/testosterone clamp. J Clin Endocrinol Metab 2009; 94:2544-50. [PMID: 19351731 PMCID: PMC2708950 DOI: 10.1210/jc.2008-2767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Sex steroids are prominent regulators of pulsatile GH secretion. HYPOTHESIS An experimentally controlled sex-steroid milieu will permit detection of nonsteroidal factors that determine GH secretion. SUBJECTS Eleven young (age, 24 +/- 0.99 yr) and 11 older (64 +/- 2.4 yr) men participated in the study. LOCATION The study was conducted at a tertiary medical center. METHODS The study consisted of GnRH-agonist down-regulation of the gonadal axis followed by fixed-dose testosterone (T) replacement (leuprolide/T clamp) and consecutive infusion of l-arginine and GHRH or GH-releasing peptide-2 (GHRP-2) to quantify peptide-secretagogue efficacies. OUTCOMES The experimental leuprolide/T clamp yielded statistically age-comparable total, bioavailable, and free T and estradiol (E(2)) concentrations. In this controlled milieu, sequential l-arginine/GHRH infusion stimulated 1.4-fold more (P = 0.021) and l-arginine/GHRP-2 1.3-fold more (P = 0.045) GH release in young than older men. Abdominal visceral fat (AVF) correlated negatively with both GHRH (P = 0.0006; R(2) = 0.39) and GHRP-2 (R(2) = 0.29) efficacy, whereas IGF-I positively predicted the same endpoints (R(2) = 0.25 to 0.30). In multivariate analysis, AVF emerged as a dominant negative determinant of GHRH efficacy (P = 0.002; R(2) = 0.41) and IGF-I as a primary positive determinant of GHRP-2 efficacy (P = 0.007; R(2) = 0.31). CONCLUSION During fixed T/E(2) availability, AVF contributes 41% of the GH-response variability to maximal GHRH drive, whereas IGF-I accounts for 31% of that for GHRP-2. Accordingly, a statistically equalized sex-steroid milieu permits dissection of age-independent and T/E(2)-independent modulators of GHRH and GHRP efficacy in men.
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Affiliation(s)
- Johannes D Veldhuis
- Department of Medicine, Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Veldhuis JD, Keenan DM, Bailey JN, Adeniji AM, Miles JM, Bowers CY. Novel relationships of age, visceral adiposity, insulin-like growth factor (IGF)-I and IGF binding protein concentrations to growth hormone (GH) releasing-hormone and GH releasing-peptide efficacies in men during experimental hypogonadal clamp. J Clin Endocrinol Metab 2009; 94:2137-43. [PMID: 19351723 PMCID: PMC2690428 DOI: 10.1210/jc.2009-0136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Sex steroids influence GH secretion in complex ways. HYPOTHESIS Analyses in a low sex-steroid milieu will help unveil the effects of age and other nonsteroidal regulators on GH secretion. CONTEXT The study was conducted in a tertiary medical center. SUBJECTS The study group included 13 healthy young men and 12 healthy older men. METHODS We used GnRH agonist-induced down-regulation of testosterone and estradiol secretion, followed by consecutive infusion of l-arginine and GHRH or GHRP-2, to test secretagogue efficacies. OUTCOMES We measured basal and pulsatile GH secretion. RESULTS During experimental testosterone/estradiol deprivation, older (57 +/- 1.7 yr) men maintained: 1) 6.8-fold less pulsatile GH secretion (P < 0.001); and 2) 2-fold lower maximal GH responses to GHRH (P = 0.0065) and GHRP-2 (P = 0.022) than young (23 +/- 1.1 yr old) individuals. Stepwise forward-selection regression analyses identified: 1) abdominal visceral fat as a dominant negative predictor of both GHRH (R(2) = 0.49; P = 0.001) and GHRP-2 (R(2) = 0.38; P = 0.005) efficacies; and 2) fasting IGF-I concentration as a major positive correlate of GHRH (R(2) = 0.52; P < 0.001) and GHRP-2 (R(2) = 0.31; P = 0.018) efficacies. Unstimulated pulsatile GH secretion was jointly correlated with IGF-I and IGFBP-3 (P = 0.039). CONCLUSION Measures of body composition (abdominal visceral fat) and pulsatile GH action (IGF-I) explain up to one half of interindividual variability in the efficacies of GHRH and GHRP-2 in sex steroid-depleted men. Accordingly, normative ranges for maximal single peptide-stimulated GH secretion in short-term hypogonadal states should incorporate the influence of these determinants as well as age.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Veldhuis JD, Mielke KL, Cosma M, Soares-Welch C, Paulo R, Miles JM, Bowers CY. Aromatase and 5alpha-reductase inhibition during an exogenous testosterone clamp unveils selective sex steroid modulation of somatostatin and growth hormone secretagogue actions in healthy older men. J Clin Endocrinol Metab 2009; 94:973-81. [PMID: 19088159 PMCID: PMC2681279 DOI: 10.1210/jc.2008-2108] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND How endogenous testosterone (Te), 5alpha-dihydrotestosterone (DHT), and estradiol (E(2)) regulate pulsatile GH secretion is not understood. HYPOTHESIS Conversion of Te to androgenic (Te-->DHT) or estrogenic (Te-->E(2)) products directs GH secretion. SUBJECTS AND LOCATION: Healthy older men (N = 42, ages 50-79 yr) participated at an academic medical center. METHODS We inhibited 5alpha-reduction with dutasteride and aromatization with anastrozole during a pharmacological Te clamp and infused somatostatin (SS), GHRH, GH-releasing peptide-2 (GHRP-2), and L-arginine/GHRH/GHRP-2 (triple stimulus) to modulate GH secretion. ENDPOINTS Deconvolution-estimated basal and pulsatile GH secretion was assessed. RESULTS Administration of Te/placebo elevated Te by 2.8-fold, DHT by 2.6-fold, and E(2) concentrations by 1.9-fold above placebo/placebo. Te/dutasteride and Te/anastrozole reduced stimulated DHT and E(2) by 89 and 86%, respectively. Stepwise forward-selection regression analysis revealed that 1) Te positively determines mean (P = 0.017) and peak (P < 0.001) GH concentrations, basal GH secretion (P = 0.015), and pulsatile GH secretion stimulated by GHRP-2 (P < 0.001); 2) Te and E(2) jointly predict GH responses to the triple stimulus (positively for Te, P = 0.006, and negatively for E(2), P = 0.031); and 3) DHT correlates positively with pulsatile GH secretion during SS infusion (P = 0.011). These effects persisted when abdominal visceral fat was included in the regression. CONCLUSION The present outcomes suggest a tetrapartite model of GH regulation in men, in which systemic concentrations of Te, DHT, and E(2) along with abdominal visceral fat determine the selective actions of GH secretagogues and SS.
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Affiliation(s)
- Johannes D Veldhuis
- Department of Internal Medicine and Pediatrics, Endocrine Research Unit, Clinical Translational Research Center, Mayo Medical and Graduate Schools, Mayo Clinic, Rochester Minnesota 55901, USA.
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Abstract
Approximately half of patients with HIV-infection develop abnormal body fat distribution, characterized by increased abdominal, breast, and dorsocervical adiposity and decreased fat in the limbs and face in association with antiretroviral therapy. Changes in fat distribution are associated with dyslipidemia, insulin resistance, and increased cardiovascular risk in patients with HIV lipodystrophy. Growth hormone secretion is reduced and responses to standardized stimulation testing altered, suggesting relative growth hormone deficiency in this population. Growth hormone secretion is characterized by normal pulse frequency, but decreased pulse amplitude, pulse width, and trough GH levels compared to weight matched, non-HIV-infected patients. Abnormalities in GH secretion are strongly associated with body composition and metabolic abnormalities in patients with HIV lipodystrophy, particularly with increased visceral fat and elevated free fatty acids. Increased somatostatin tone and decreased ghrelin concentrations may also contribute to reduced GH levels. Administration of exogenous GH or growth hormone releasing hormone (GHRH) to normalize growth hormone concentrations is effective to reduce visceral fat and improve lipid parameters in HIV-infected patients. Treatment with supraphysiologic GH is limited by side effects and exacerbation of insulin resistance, whereas administration of physiologic doses of GH demonstrates more modest treatment effects but fewer adverse effects. Initial studies of GHRH also show significant reductions in visceral adipose tissue (VAT) with potentially fewer adverse effects. GHRH may be particularly useful to normalize GH dynamics in patients with HIV lipodystrophy by increasing endogenous GH pulse height, GH pulse width, and trough GH levels, while preserving the negative feedback of IGF-I on pituitary GH secretion.
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Affiliation(s)
- Takara L Stanley
- Program in Nutritional Metabolism and Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, LON5-207, 55 Fruit St., Boston, MA, 02114, USA
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Veldhuis JD. Aging and hormones of the hypothalamo-pituitary axis: gonadotropic axis in men and somatotropic axes in men and women. Ageing Res Rev 2008; 7:189-208. [PMID: 18343203 DOI: 10.1016/j.arr.2007.12.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 12/18/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
Neuroendocrinology of the aging (male) gonadal and (male and female) somatotropic axes will be reviewed. A companion chapter discusses reproductive hormonal changes in aging women. Both the gonadal and growth-hormone/insulin-like growth factor (GH/IGF-I) axes function as ensembles. The ensembles comprise tripartite interactions among the brain (hypothalamus), anterior pituitary gland (gonadotrope and somatotrope cells) and target organs (testis, liver, muscle, fat and brain). Compelling evidence indicates that combined hypothalamic and gonadal adaptations operate in the reproductive axis of older men, and multiple hypothalamic adaptations prevail in the GH axis of elderly men and women. Evolving investigative methods allow more precise parsing of the particular mechanisms that subserve such age-related changes, and suggest novel interventional strategies to evaluate the physiological impact of the dynamic alterations discerned in aging individuals.
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Veldhuis JD, Cosma M, Erickson D, Paulo R, Mielke K, Farhy LS, Bowers CY. Tripartite control of growth hormone secretion in women during controlled estradiol repletion. J Clin Endocrinol Metab 2007; 92:2336-45. [PMID: 17405836 DOI: 10.1210/jc.2007-0043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Studies of how aging attenuates GH secretion are confounded by differences in sex-steroid milieus, abdominal visceral fat mass (AVF), and IGF-I concentrations and limited in interpretability by the use of pharmacological doses of secretagogues. HYPOTHESIS In a controlled estrogenic milieu, near-physiological secretagogue drive will unmask distinct influences of age, AVF, and IGF-I on GH secretion. LOCATION The study was conducted at an academic medical center. SUBJECTS Subjects included 10 healthy pre- (PRE) and 10 postmenopausal (POST) women. PROCEDURE In a defined estradiol (E(2)) milieu, we compared GH secretion after submaximal stimulation with GH-releasing peptide (GHRP)-2 (ghrelin analog), GHRH, and l-arginine (an inhibitor of somatostatin outflow). ANALYSIS We related GH responses to age stratum (dichotomous variable) and AVF and IGF-I concentrations (continuous variables). RESULTS In the face of comparable concentrations of E(2), testosterone, and SHBG: 1) age (P < 0.001) and secretagogue type (P < 0.001) independently determined GH secretion; 2) GH responses in POST subjects were only 26-33% of those in PRE (P < or = 0.002) across all secretagogues; 3) POST women lost the PRE order of secretagogue potency (GHRP-2 > GHRH = l-arginine); and 4) in the combined cohorts, higher AVF predicted reduced l-arginine-stimulated GH secretion (R(2) = 0.46, P = 0.0013), whereas higher IGF-I concentrations forecast increased GHRP-2 and GHRH drive (R(2) > or = 0.52, P < or = 0.013). CONCLUSION A paradigm of near-physiological secretagogue drive in an E(2)-clamped milieu unmasks tripartite deficits in peptide-signaling pathways in healthy POST, compared with PRE, women. Post hoc analyses indicate that both greater visceral adiposity and lower IGF-I concentrations mark this triple regulatory defect.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit 9, General Clinical Research Center, Mayo Medical and Graduate Schools of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2007; 14:74-89. [PMID: 17940424 DOI: 10.1097/med.0b013e32802e6d87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Veldhuis JD, Roemmich JN, Richmond EJ, Bowers CY. Somatotropic and gonadotropic axes linkages in infancy, childhood, and the puberty-adult transition. Endocr Rev 2006; 27:101-40. [PMID: 16434512 DOI: 10.1210/er.2005-0006] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Integrative neuroendocrine control of the gonadotropic and somatotropic axes in childhood, puberty, and young adulthood proceeds via multiple convergent and divergent pathways in the human and experimental animal. Emerging ensemble concepts are required to embody independent, parallel, and interacting mechanisms that subserve physiological adaptations and pathological disruption of reproduction and growth. Significant advances in systems biology will be needed to address these challenges.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Department of Internal Medicine, Mayo Medical School, Mayo School of Graduate Medical Education, General Clinical Research Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
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