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Finan B, Parlee SD, Yang B. Nuclear hormone and peptide hormone therapeutics for NAFLD and NASH. Mol Metab 2020; 46:101153. [PMID: 33359400 PMCID: PMC8085542 DOI: 10.1016/j.molmet.2020.101153] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 12/13/2022] Open
Abstract
Background Non-alcoholic steatohepatitis (NASH) is a spectrum of histological liver pathologies ranging from hepatocyte fat accumulation, hepatocellular ballooning, lobular inflammation, and pericellular fibrosis. Based on early investigations, it was discovered that visceral fat accumulation, hepatic insulin resistance, and atherogenic dyslipidemia are pathological triggers for NASH progression. As these pathogenic features are common with obesity, type 2 diabetes (T2D), and atherosclerosis, therapies that target dysregulated core metabolic pathways may hold promise for treating NASH, particularly as first-line treatments. Scope of Review In this review, the latest clinical data on nuclear hormone- and peptide hormone-based drug candidates for NASH are reviewed and contextualized, culminating with a discovery research perspective on emerging combinatorial therapeutic approaches that merge nuclear and peptide strategies. Major Conclusion Several drug candidates targeting the metabolic complications of NASH have shown promise in early clinical trials, albeit with unique benefits and challenges, but questions remain regarding their translation to larger and longer clinical trials, as well as their utility in a more diseased patient population. Promising polypharmacological approaches can potentially overcome some of these perceived challenges, as has been suggested in preclinical models, but deeper characterizations are required to fully evaluate these opportunities. Despite no approved treatments for NASH, several drug candidates have shown promise in early clinical trials. Therapies targeting metabolic pathologies of NASH have shown efficacy to reduce hepatic fat content and improve fibrosis. Many of these therapies have been rationally designed to mimic nuclear hormone or peptide hormone action. Despite provocative preclinical findings of nuclear and peptide hormone combination, clinical translation remains unproven.
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Affiliation(s)
- Brian Finan
- Novo Nordisk Research Center Indianapolis, Inc., United States.
| | | | - Bin Yang
- Novo Nordisk Research Center Indianapolis, Inc., United States
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Roelfsema F, Veldhuis JD. Growth Hormone Dynamics in Healthy Adults Are Related to Age and Sex and Strongly Dependent on Body Mass Index. Neuroendocrinology 2016; 103:335-44. [PMID: 26228064 PMCID: PMC4731317 DOI: 10.1159/000438904] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 07/15/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Studies on 24-hour growth hormone (GH) secretion are rare. The influences of sex, age, and adiposity are well recognized but generally derived from specific, selected subject groups, not spanning sexes, many age decades, and a range of body weights. OBJECTIVE Our goal was to investigate GH dynamics in a group of 130 healthy adult subjects, both men and women, across 5 age decades as well as a 2.5-fold range of body mass index (BMI) values. METHODS GH was measured by a sensitive immunofluorometric assay. Secretion parameters were quantified by automated deconvolution and relative pattern randomness by approximate entropy (ApEn). RESULTS The median age was 40 years (range 20-77). The median BMI was 26 (range 18.3-49.8). Pulsatile 24-hour GH secretion was negatively correlated with age (p = 0.002) and BMI (p < 0.0001). Basal GH secretion negatively correlated with BMI (p = 0.003) but not with age. The sex- dependent GH secretion (greater in women) was no longer detectable after 50 years of age. Insulin-like growth factor (IGF)-1 levels were lower in women over 50 years of age compared with men of a similar age. ApEn showed an age-related increase in both sexes and was higher in premenopausal and postmenopausal women than in men of comparable age (p < 0.0001). A single fasting GH measurement is not informative of 24-hour GH secretion. CONCLUSIONS BMI dominates the negative regulation of 24-hour GH secretion across 5 decades of age in this up till now largest cohort of healthy adults who underwent 24-hour blood sampling. Sex also impacts GH secretion before the age of 50 years as well as its regularity at all ages. Differences in serum IGF-1 partly depend on the pre- or postmenopausal state. Finally, a single GH measurement is not informative of 24-hour GH secretion.
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Affiliation(s)
- Ferdinand Roelfsema
- Department of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands
| | - Johannes D. Veldhuis
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Murray PG, Higham CE, Clayton PE. 60 YEARS OF NEUROENDOCRINOLOGY: The hypothalamo-GH axis: the past 60 years. J Endocrinol 2015; 226:T123-40. [PMID: 26040485 DOI: 10.1530/joe-15-0120] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/03/2015] [Indexed: 12/19/2022]
Abstract
At the time of the publication of Geoffrey Harris's monograph on 'Neural control of the pituitary gland' 60 years ago, the pituitary was recognised to produce a growth factor, and extracts administered to children with hypopituitarism could accelerate growth. Since then our understanding of the neuroendocrinology of the GH axis has included identification of the key central components of the GH axis: GH-releasing hormone and somatostatin (SST) in the 1970s and 1980s and ghrelin in the 1990s. Characterisation of the physiological control of the axis was significantly advanced by frequent blood sampling studies in the 1980s and 1990s; the pulsatile pattern of GH secretion and the factors that influenced the frequency and amplitude of the pulses have been defined. Over the same time, spontaneously occurring and targeted mutations in the GH axis in rodents combined with the recognition of genetic causes of familial hypopituitarism demonstrated the key factors controlling pituitary development. As the understanding of the control of GH secretion advanced, developments of treatments for GH axis disorders have evolved. Administration of pituitary-derived human GH was followed by the introduction of recombinant human GH in the 1980s, and, more recently, by long-acting GH preparations. For GH excess disorders, dopamine agonists were used first followed by SST analogues, and in 2005 the GH receptor blocker pegvisomant was introduced. This review will cover the evolution of these discoveries and build a picture of our current understanding of the hypothalamo-GH axis.
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Affiliation(s)
- P G Murray
- Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK
| | - C E Higham
- Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK
| | - P E Clayton
- Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK Centre for Paediatrics and Child HealthInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UKDepartment of Paediatric EndocrinologyRoyal Manchester Children's Hospital, Central Manchester Foundation Hospitals NHS Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UKDepartment of EndocrinologyThe Christie Hospital NHS Foundation Trust, Manchester, M20 4BX, UKCentre for Endocrinology and DiabetesInstitute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, M13 9WL, UK
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Persechini ML, Gennero I, Grunenwald S, Vezzosi D, Bennet A, Caron P. Decreased IGF-1 concentration during the first trimester of pregnancy in women with normal somatotroph function. Pituitary 2015; 18:461-4. [PMID: 25179796 DOI: 10.1007/s11102-014-0596-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
INTRODUCTION A decrease of insulin-like growth factor-I levels (IGF-I) has been reported during the first trimester of pregnancy in women with acromegaly before the secretion of placental growth hormone (GH) progressively increases IGF-1 concentration. STUDY DESIGN To evaluate variations of concentrations of IGF-1, insulin-like growth factor (IGF)-binding protein-3 (IGF-BP3) and GH during the first trimester of pregnancy in women with normal somatotroph function. PATIENTS AND METHODS Sixteen women (median age 31 years) with as who were followed for benign thyroid disorders (n = 15) or prolactin-secreting microadenoma (n = 1) were evaluated before and in the first trimester of pregnancy. Serum concentrations of GH, IGF-1, IGF-BP3, TSH and estradiol (E2) were measured before and in the first trimester (5.4 ± 2.2 weeks of gestation). RESULTS Before pregnancy, somatotroph and thyroid functions (median TSH 1.2 mU/L) were normal in all women. At the first trimester IGF-1 levels decreased significantly (before = 210 ng/mL, first trimester = 145 ng/mL, p < 0.001) with no significant change in GH (before = 1.5 ng/mL, first trimester = 0.84 ng/mL) or IGF-BP3 levels (before = 2.3 ng/mL, first trimester = 2.2 ng/mL), while estradiol levels increased significantly (before = 46.5 pg/100 mL, first trimester = 448.5 pg/100 mL, p < 0.001). CONCLUSION In women with normal somatotroph function, IGF-1 levels decrease in the first trimester of pregnancy without changes in GH or IGF-BP3 levels. These results confirm liver resistance to GH as a consequence of the physiological increase of estrogens during the first trimester.
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Affiliation(s)
- Marie-Laure Persechini
- Department of Endocrinology and Metabolic Diseases, Pôle Cardio-Vasculaire et Métabolique, CHU Larrey, 24 Chemin de Pouvourville, TSA 30030, 31059, Toulouse Cedex 9, France
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Norman C, Rollene N, Weist SM, Wigham JR, Erickson D, Miles JM, Bowers CY, Veldhuis JD. Short-term estradiol supplementation potentiates low-dose ghrelin action in the presence of GHRH or somatostatin in older women. J Clin Endocrinol Metab 2014; 99:E73-80. [PMID: 24203062 PMCID: PMC3879681 DOI: 10.1210/jc.2013-3043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Ghrelin is a potent gastric-derived GH-releasing peptide. How ghrelin interacts with sex steroids, GHRH, and somatostatin (SS) is not known. OBJECTIVE Our objective was to test the hypotheses that ghrelin's interactions with GHRH (synergistic) and SS (disinhibitory) are ghrelin dose-dependent and amplified by estrogen. SUBJECTS, SETTING, AND DESIGN: Healthy postmenopausal women were treated with placebo (n=12) or 17β-estradiol (E2) (n=12) at the Center for Translational Science Activities in a randomized double-blind prospective study. METHODS Ghrelin dose-dependence was assessed by nonlinear curve fitting of the relationship between deconvolved GH secretory-burst mass and 5 randomly ordered ghrelin doses (0, 0.03, 0.135, 0.6, and 2.7 μg/kg bolus iv) during saline, GHRH, and SS infusion. RESULTS Under placebo, neither GHRH nor SS altered the ED50 of ghrelin (range 0.64-0.67 μg/kg). Under E2 (median E2 88 pg/mL), the ED50 of ghrelin declined in the presence of GHRH to 0.52 μg/kg. In contrast, the efficacy of ghrelin rose markedly during GHRH vs saline exposure with and without E2: placebo and saline 52±1.0 vs GHRH 173±3.8 μg/L; and E2 and saline 56±0.90 vs GHRH 174±3.7 μg/L. Sensitivity to ghrelin was similar under all conditions. SUMMARY Short-term E2 supplementation in postmenopausal women reduces the ED50 (increases the potency) of ghrelin when GHRH is present, without altering ghrelin efficacy (maximal effect) or hypothalamo-pituitary sensitivity (slope of dose response) to ghrelin. The data suggest possible physiological interactions among sex steroids (endogenous), ghrelin, and GHRH during E2 replacement in postmenopausal women.
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Affiliation(s)
- Catalina Norman
- Endocrine Research Unit (C.N., S.M.W., J.R.W., D.E., J.M.M., J.D.V.), Mayo School of Graduate Medical Education, Center for Translational Science Activities, Mayo Clinic, Rochester, Minnesota 55905; Naval Medical Center Portsmouth (N.R.), Division of Reproductive Endocrinology, Portsmouth, Virginia 23708; and Tulane University Health Sciences Center (C.Y.B.), Endocrinology and Metabolism Section, Peptide Research Section, New Orleans, Louisiana 70112
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Norman C, Miles J, Bowers CY, Veldhuis JD. Differential pulsatile secretagogue control of GH secretion in healthy men. Am J Physiol Regul Integr Comp Physiol 2013; 304:R712-9. [PMID: 23485864 DOI: 10.1152/ajpregu.00069.2013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pulsatile growth hormone (GH) secretion putatively reflects integrated regulation by GH-releasing hormone (GHRH), somatostatin (SST), and GH-releasing peptide (GHRP). GHRH and SST secretion is itself pulsatile. However, how GHRH and SST pulses act along with GHRP to jointly determine pulsatile GH secretion is unclear. Moreover, how testosterone (T) modulates such interactions is unknown. These queries were assessed in a prospectively randomized, placebo-controlled double-blind cohort comprising 26 healthy older men randomized to testosterone (T) vs. placebo supplementation. Pulses of GHRH, SST, or saline were infused intravenously at 90-min intervals for 13 h, along with either continuous saline or ghrelin analog (GHRP-2). The train of pulses was followed by a triple stimulus (combined l-arginine, GHRH, and GHRP-2) to estimate near-maximal GH secretion over a final 3 h. Testosterone vs. placebo supplementation doubled pulsatile GH secretion during GHRH pulses combined with continuous saline (GHRH/saline) (P < 0.01). Pulsatile GH secretion correlated positively with T concentrations (270-1,170 ng/dl) in the 26 men during saline pulses/saline (P = 0.015, R(2) = 0.24), GHRH pulses/saline (P = 0.020, R(2) = 0.22), and combined GHRH pulses/GHRP-2 (P = 0.016, R(2) = 0.25) infusions. Basal nonpulsatile GH secretion correlated with T during saline pulses/GHRP-2 drive (P = 0.020, R(2) = 0.16). By regression analysis, pulsatile GH secretion varied negatively with body mass index (BMI) during saline/GHRP-2 infusion (P = 0.001, R(2) = 0.36), as well as after the triple stimulus preceded by GHRH/GHRP-2 (P = 0.013, R(2) = 0.23). Mean (10-h) GH concentrations under GHRP-2 were predicted jointly by estradiol (positively) and BMI (negatively) (P < 0.001, R(2) = 0.520). These data indicate that estradiol, T, and BMI control pulsatile secretagogue-specific GH-regulatory mechanisms in older men.
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Affiliation(s)
- Catalina Norman
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905, USA
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Veldhuis JD, Norman C, Miles JM, Bowers CY. Sex steroids, GHRH, somatostatin, IGF-I, and IGFBP-1 modulate ghrelin's dose-dependent drive of pulsatile GH secretion in healthy older men. J Clin Endocrinol Metab 2012; 97:4753-60. [PMID: 22990092 PMCID: PMC3513533 DOI: 10.1210/jc.2012-2567] [Citation(s) in RCA: 12] [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: 02/08/2023]
Abstract
CONTEXT Ghrelin is a potent endogenous stimulator of GH secretion. However, clinical factors that regulate ghrelin dose-responsiveness are incompletely defined. OBJECTIVE The aim of the study was to test the multipathway hypothesis that testosterone (T) and estradiol, GHRH, and somatostatin (SS) jointly modulate ghrelin's action. DESIGN/PARTICIPANTS/SETTING Healthy older men (n = 21) participated in a double-blind, prospectively randomized, placebo (Pl)-controlled study in a Clinical Translational Research Center. INTERVENTIONS To create a range of sex-steroid milieus, men received leuprolide + Pl (n = 10) or leuprolide + T addback (n = 11). Sixteen to 21 d later, subjects received three separate randomly ordered overnight constant i.v. infusions of saline, GHRH, and SS. Interactions between the peptide clamp and ghrelin were tested by superimposed injections of four randomly ordered bolus i.v. doses of ghrelin (0.03, 0.135, 0.60, and 2.7 μg/kg). GH was measured every 10 min, and GH responses were assessed by nonlinear dose-response analysis. Linear associations were assessed by stepwise regression. OUTCOME MEASURES/RESULTS The descending numerical order of ghrelin efficacy (maximal GH secretory-burst mass; micrograms/liter) was 107 (GHRH + Pl), 104 (GHRH + T), 73 (saline + T), 73 (SS + T), 60 (saline + Pl), and 52 (SS + Pl) [means], wherein SS + T exceeded SS + Pl. GHRH and IGF binding protein-1 augmented, whereas IGF-I attenuated ghrelin potency. Age and IGF-I decreased ghrelin/GHRH synergy. Ghrelin sensitivity was independent of interventions. CONCLUSIONS These studies introduce composite regulatory effects of sex hormones, GHRH, SS, IGF binding protein-1, and IGF-I on ghrelin dose-responsiveness, suggesting multipathway modulation of GH-secretagogue action.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, National Institutes of Health Center for Translational Science Activities, Mayo Clinic, Rochester, Minnesota 55905, USA.
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Cuatrecasas G, Alegre C, Fernandez-Solà J, Gonzalez MJ, Garcia-Fructuoso F, Poca-Dias V, Nadal A, Cuatrecasas G, Navarro F, Mera A, Lage M, Peinó R, Casanueva F, Liñan C, Sesmilo G, Coves MJ, Izquierdo JP, Alvarez I, Granados E, Puig-Domingo M. Growth hormone treatment for sustained pain reduction and improvement in quality of life in severe fibromyalgia. Pain 2012; 153:1382-1389. [DOI: 10.1016/j.pain.2012.02.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 02/07/2012] [Accepted: 02/13/2012] [Indexed: 10/28/2022]
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Prolactin secretion in healthy adults is determined by gender, age and body mass index. PLoS One 2012; 7:e31305. [PMID: 22363612 PMCID: PMC3281966 DOI: 10.1371/journal.pone.0031305] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 01/06/2012] [Indexed: 11/26/2022] Open
Abstract
Background Prolactin (PRL) secretion is quantifiable as mean, peak and nadir PRL concentrations, degree of irregularity (ApEn, approximate entropy) and spikiness (brief staccato-like fluctuations). Hypothesis Distinct PRL dynamics reflect relatively distinct (combinations of) subject variables, such as gender, age, and BMI. Location Clinical Research Unit. Subjects Seventy-four healthy adults aged 22–77 yr (41 women and 33 men), with BMI 18.3–39.4 kg/m2. Measures Immunofluorometric PRL assay of 10-min samples collected for 24 hours. Results Mean 24-h PRL concentration correlated jointly with gender (P<0.0001) and BMI (P = 0.01), but not with age (overall R2 = 0.308, P<0.0001). Nadir PRL concentration correlated with gender only (P = 0.017) and peak PRL with gender (P<0.001) and negatively with age (P<0.003), overall R2 = 0.325, P<0.0001. Forward-selection multivariate regression of PRL deconvolution results demonstrated that basal (nonpulsatile) PRL secretion tended to be associated with BMI (R2 = 0.058, P = 0.03), pulsatile secretion with gender (R2 = 0.152, P = 0.003), and total secretion with gender and BMI (R2 = 0.204, P<0.0001). Pulse mass was associated with gender (P = 0.001) and with a negative tendency to age (P = 0.038). In male subjects older than 50 yr (but not in women) approximate entropy was increased (0.942±0.301 vs. 1.258±0.267, P = 0.007) compared with younger men, as well as spikiness (0.363±0.122 vs. 0463±2.12, P = 0.031). Cosinor analysis disclosed higher mesor and amplitude in females than in men, but the acrophase was gender-independent. The acrophase was determined by age and BMI (R2 = 0.186, P = 0.001). Conclusion In healthy adults, selective combinations of gender, age, and BMI specify distinct PRL dynamics, thus requiring balanced representation of these variables in comparative PRL studies.
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Veldhuis JD, Bowers CY. Regulated recovery of pulsatile growth hormone secretion from negative feedback: a preclinical investigation. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1143-52. [PMID: 21795635 DOI: 10.1152/ajpregu.00293.2011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although stimulatory (feedforward) and inhibitory (feedback) dynamics jointly control neurohormone secretion, the factors that supervise feedback restraint are poorly understood. To parse the regulation of growth hormone (GH) escape from negative feedback, 25 healthy men and women were studied eight times each during an experimental GH feedback clamp. The clamp comprised combined bolus infusion of GH or saline and continuous stimulation by saline GH-releasing hormone (GHRH), GHRP-2, or both peptides after randomly ordered supplementation with placebo (both sexes) vs. E(2) (estrogen; women) and T (testosterone; men). Endpoints were GH pulsatility and entropy (a model-free measure of feedback quenching). Gender determined recovery of pulsatile GH secretion from negative feedback in all four secretagog regimens (0.003 ≤ P ≤ 0.017 for women>men). Peptidyl secretagog controlled the mass, number, and duration of feedback-inhibited GH secretory bursts (each, P < 0.001). E(2)/T administration potentiated both pulsatile (P = 0.006) and entropic (P < 0.001) modes of GH recovery. IGF-I positively predicted the escape of GH secretory burst number and mode (P = 0.022), whereas body mass index negatively forecast GH secretory burst number and mass (P = 0.005). The composite of gender, body mass index, E(2), IGF-I, and peptidyl secretagog strongly regulates the escape of pulsatile and entropic GH secretion from autonegative feedback. The ensemble factors identified in this preclinical investigation enlarge the dynamic model of GH control in humans.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905, USA.
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Veldhuis JD, Erickson D, Miles JM, Bowers CY. Complex regulation of GH autofeedback under dual-peptide drive: studies under a pharmacological GH and sex steroid clamp. Am J Physiol Endocrinol Metab 2011; 300:E1158-65. [PMID: 21467302 PMCID: PMC3118586 DOI: 10.1152/ajpendo.00054.2011] [Citation(s) in RCA: 6] [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] [Indexed: 11/22/2022]
Abstract
To test the postulate that sex difference, sex steroids, and peptidyl secretagogues control GH autofeedback, 11 healthy postmenopausal women and 14 older men were each given 1) a single iv pulse of GH to enforce negative feedback and 2) continuous iv infusion of saline vs. combined GHRH/GHRP-2 to drive feedback escape during pharmacological estradiol (E(2); women) or testosterone (T; men) supplementation vs. placebo in a double-blind, prospectively randomized crossover design. By three-way ANCOVA, sex difference, sex hormone treatment, peptide stimulation, and placebo/saline responses (covariate) controlled total (integrated) GH recovery during feedback (each P < 0.001). Both sex steroid milieu (P = 0.019) and dual-peptide stimulation (P < 0.001) determined nadir (maximally feedback-suppressed) GH concentrations. E(2)/T exposure elevated nadir GH concentrations during saline infusion (P = 0.003), whereas dual-peptide infusion did so independently of T/E(2) and sex difference (P = 0.001). All three of sex difference (P = 0.001), sex steroid treatment (P = 0.005), and double-peptide stimulation (P < 0.001) augmented recovery of peak (maximally feedback-escaped) GH concentrations. Peak GH responses to dual-peptidyl agonists were greater in women than in men (P = 0.016). E(2)/T augmented peak GH recovery during saline infusion (P < 0.001). Approximate entropy analysis corroborated independent effects of sex steroid treatment (P = 0.012) and peptide infusion (P < 0.001) on GH regularity. In summary, sex difference, sex steroid supplementation, and combined peptide drive influence nadir, peak, and entropic measurements of GH release under controlled negative feedback. To the degree that the pharmacological sex steroid, GH, and dual-peptide clamps provide prephysiological regulatory insights, these outcomes suggest major determinants of pulsatile GH secretion in the feedback domain.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Center for Translational Science Activities, MayoClinic, Rochester, MN 55905, USA.
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