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Shefner JM, Musaro A, Ngo ST, Lunetta C, Steyn FJ, Robitaille R, De Carvalho M, Rutkove S, Ludolph AC, Dupuis L. Skeletal muscle in amyotrophic lateral sclerosis. Brain 2023; 146:4425-4436. [PMID: 37327376 PMCID: PMC10629757 DOI: 10.1093/brain/awad202] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/16/2023] [Accepted: 05/30/2023] [Indexed: 06/18/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS), the major adult-onset motor neuron disease, has been viewed almost exclusively as a disease of upper and lower motor neurons, with muscle changes interpreted as a consequence of the progressive loss of motor neurons and neuromuscular junctions. This has led to the prevailing view that the involvement of muscle in ALS is only secondary to motor neuron loss. Skeletal muscle and motor neurons reciprocally influence their respective development and constitute a single functional unit. In ALS, multiple studies indicate that skeletal muscle dysfunction might contribute to progressive muscle weakness, as well as to the final demise of neuromuscular junctions and motor neurons. Furthermore, skeletal muscle has been shown to participate in disease pathogenesis of several monogenic diseases closely related to ALS. Here, we move the narrative towards a better appreciation of muscle as a contributor of disease in ALS. We review the various potential roles of skeletal muscle cells in ALS, from passive bystanders to active players in ALS pathophysiology. We also compare ALS to other motor neuron diseases and draw perspectives for future research and treatment.
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Affiliation(s)
- Jeremy M Shefner
- Barrow Neurological Institute, Phoenix, AZ, USA
- College of Medicine, University of Arizona, Phoenix, AZ, USA
- College of Medicine, Creighton University, Phoenix, AZ, USA
| | - Antonio Musaro
- DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia—Fondazione Cenci Bolognetti, Scuola Superiore di Studi Avanzati Sapienza (SSAS), Rome, Italy
| | - Shyuan T Ngo
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Christian Lunetta
- Neurorehabilitation Department, Istituti Clinici Scientifici Maugeri IRCCS, Milan, Italy
| | - Frederik J Steyn
- Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Richard Robitaille
- Département de neurosciences, CIRCA, Université de Montréal, Montréal H7G 1T7, Canada
| | - Mamede De Carvalho
- Instituto de Fisiologia, Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Seward Rutkove
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Albert C Ludolph
- Department of Neurology, University of Ulm, Ulm, Germany
- Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Ulm, Germany
| | - Luc Dupuis
- Université de Strasbourg, Inserm, UMR-S1118, Mécanismes centraux et périphériques de la neurodégénérescence, CRBS, Strasbourg, France
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2
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Killoy KM, Pehar M, Harlan BA, Vargas MR. Altered expression of clock and clock-controlled genes in a hSOD1-linked amyotrophic lateral sclerosis mouse model. FASEB J 2021; 35:e21343. [PMID: 33508151 DOI: 10.1096/fj.202000386rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 12/12/2020] [Accepted: 12/20/2020] [Indexed: 11/11/2022]
Abstract
Most physiological processes in mammals are subjected to daily oscillations that are governed by a circadian system. The circadian rhythm orchestrates metabolic pathways in a time-dependent manner and loss of circadian timekeeping has been associated with cellular and system-wide alterations in metabolism, redox homeostasis, and inflammation. Here, we investigated the expression of clock and clock-controlled genes in multiple tissues (suprachiasmatic nucleus, spinal cord, gastrocnemius muscle, and liver) from mutant hSOD1-linked amyotrophic lateral sclerosis (ALS) mouse models. We identified tissue-specific changes in the relative expression, as well as altered daily expression patterns, of clock genes, sirtuins (Sirt1, Sirt3, and Sirt6), metabolic enzymes (Pfkfb3, Cpt1, and Nampt), and redox regulators (Nrf2, G6pd, and Pgd). In addition, astrocytes transdifferentiated from induced pluripotent stem cells from SOD1-linked and FUS RNA binding protein-linked ALS patients also displayed altered expression of clock genes. Overall, our results raise the possibility of disrupted cross-talk between the suprachiasmatic nucleus and peripheral tissues in hSOD1G93A mice, preventing proper peripheral clock regulation and synchronization. Since these changes were observed in symptomatic mice, it remains unclear whether this dysregulation directly drives or it is a consequence of the degenerative process. However, because metabolism and redox homeostasis are intimately entangled with circadian rhythms, our data suggest that altered expression of clock genes may contribute to metabolic and redox impairment in ALS. Since circadian dyssynchrony can be rescued, these results provide the groundwork for potential disease-modifying interventions.
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Affiliation(s)
- Kelby M Killoy
- Biomedical Sciences Training Program, Medical University of South Carolina, Charleston, SC, USA
| | - Mariana Pehar
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Benjamin A Harlan
- Biomedical Sciences Training Program, Medical University of South Carolina, Charleston, SC, USA
| | - Marcelo R Vargas
- Department of Neurology, University of Wisconsin-Madison, Madison, WI, USA
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3
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Tomas D, McLeod VM, Chiam MDF, Wanniarachchillage N, Boon WC, Turner BJ. Dissociation of disease onset, progression and sex differences from androgen receptor levels in a mouse model of amyotrophic lateral sclerosis. Sci Rep 2021; 11:9255. [PMID: 33927243 PMCID: PMC8085012 DOI: 10.1038/s41598-021-88415-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/30/2021] [Indexed: 01/14/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disorder caused by loss of motor neurons. ALS incidence is skewed towards males with typically earlier age of onset and limb site of onset. The androgen receptor (AR) is the major mediator of androgen effects in the body and is present extensively throughout the central nervous system, including motor neurons. Mutations in the AR gene lead to selective lower motor neuron degeneration in male spinal bulbar muscular atrophy (SBMA) patients, emphasising the importance of AR in maintaining motor neuron health and survival. To evaluate a potential role of AR in onset and progression of ALS, we generated SOD1G93A mice with either neural AR deletion or global human AR overexpression. Using a Cre-LoxP conditional gene knockout strategy, we report that neural deletion of AR has minimal impact on the disease course in SOD1G93A male mice. This outcome was potentially confounded by the metabolically disrupted Nestin-Cre phenotype, which likely conferred the profound lifespan extension observed in the SOD1G93A double transgenic male mice. In addition, overexpression of human AR produced no benefit to disease onset and progression in SOD1G93A mice. In conclusion, the disease course of SOD1G93A mice is independent of AR expression levels, implicating other mechanisms involved in mediating the sex differences in ALS. Our findings using Nestin-Cre mice, which show an inherent metabolic phenotype, led us to hypothesise that targeting hypermetabolism associated with ALS may be a more potent modulator of disease, than AR in this mouse model.
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Affiliation(s)
- Doris Tomas
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Victoria M McLeod
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Mathew D F Chiam
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Nayomi Wanniarachchillage
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Wah C Boon
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Bradley J Turner
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia.
- Perron Institute for Neurological and Translational Science, Queen Elizabeth Medical Centre, Nedlands, WA, 6150, Australia.
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4
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Ngo ST, Wang H, Henderson RD, Bowers C, Steyn FJ. Ghrelin as a treatment for amyotrophic lateral sclerosis. J Neuroendocrinol 2021; 33:e12938. [PMID: 33512025 DOI: 10.1111/jne.12938] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/27/2022]
Abstract
Ghrelin is a gut hormone best known for its role in regulating appetite and stimulating the secretion of the anabolic hormone growth hormone (GH). However, there is considerable evidence to show wider-ranging biological actions of ghrelin that favour improvements in cellular and systemic metabolism, as well as neuroprotection. Activation of these ghrelin-mediated pathways may alleviate pathogenic processes that are assumed to contribute to accelerated progression of disease in patients with neurodegenerative disease. Here, we provide a brief overview on the history of discoveries that led to the identification of ghrelin. Focussing on the neurodegenerative disease amyotrophic lateral sclerosis (ALS), we also present an overview of emerging evidence that suggests that ghrelin and ghrelin mimetics may serve as potential therapies for the treatment of ALS. Given that ALS is a highly heterogeneous disease, where multiple disease mechanisms contribute to variability in disease onset and rate of disease progression, we speculate that the wide-ranging biological actions of ghrelin might offer therapeutic benefit through modulating multiple disease-relevant processes observed in ALS. Expanding on the well-known actions of ghrelin in regulating food intake and GH secretion, we consider the potential of ghrelin-mediated pathways in improving body weight regulation, metabolism and the anabolic and neuroprotective actions of GH and insulin-like growth factor-1 (IGF-1). This is of clinical significance because loss of body weight, impairments in systemic and cellular metabolism, and reductions in IGF-1 are associated with faster disease progression and worse disease outcome in patients with ALS.
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Affiliation(s)
- Shyuan T Ngo
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
- Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD, Australia
| | - Hao Wang
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Robert D Henderson
- Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD, Australia
| | - Cyril Bowers
- Department of Internal Medicine, Tulane University Health Sciences Centre, New Orleans, LA, USA
| | - Frederik J Steyn
- Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
- Centre for Clinical Research, The University of Queensland, Brisbane, QLD, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
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5
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Terashima T, Kobashi S, Watanabe Y, Nakanishi M, Honda N, Katagi M, Ohashi N, Kojima H. Enhancing the Therapeutic Efficacy of Bone Marrow-Derived Mononuclear Cells with Growth Factor-Expressing Mesenchymal Stem Cells for ALS in Mice. iScience 2020; 23:101764. [PMID: 33251493 PMCID: PMC7677706 DOI: 10.1016/j.isci.2020.101764] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 09/16/2020] [Accepted: 10/30/2020] [Indexed: 12/14/2022] Open
Abstract
Several treatments have been attempted in amyotrophic lateral sclerosis (ALS) animal models and patients. Recently, transplantation of bone marrow-derived mononuclear cells (MNCs) was investigated as a regenerative therapy for ALS, but satisfactory treatments remain to be established. To develop an effective treatment, we focused on mesenchymal stem cells (MSCs) expressing hepatocyte growth factor, glial cell line-derived neurotrophic factor, and insulin-like growth factor using human artificial chromosome vector (HAC-MSCs). Here, we demonstrated the transplantation of MNCs with HAC-MSCs in ALS mice. As per our results, the progression of motor dysfunction was significantly delayed, and their survival was prolonged dramatically. Additional analysis revealed preservation of motor neurons, suppression of gliosis, engraftment of numerous MNCs, and elevated chemotaxis-related cytokines in the spinal cord of treated mice. Therefore, growth factor-expressing MSCs enhance the therapeutic effects of bone marrow-derived MNCs for ALS and have a high potential as a novel cell therapy for patients with ALS. MNCs with growth factor-expressing MSCs is an effective cell therapy for ALS mice The MSCs enhance therapeutic effects by migration of MNCs into ALS mice spinal cord This cell therapy suppresses neuronal loss and gliosis in ALS mice spinal cord This cell therapy induces several cytokines expression in ALS mice spinal cord
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Affiliation(s)
- Tomoya Terashima
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Shuhei Kobashi
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Yasuhiro Watanabe
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8504, Japan
| | - Mami Nakanishi
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8504, Japan
| | - Naoto Honda
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8504, Japan
| | - Miwako Katagi
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Natsuko Ohashi
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Hideto Kojima
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
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6
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Pennuto M, Pandey UB, Polanco MJ. Insulin-like growth factor 1 signaling in motor neuron and polyglutamine diseases: From molecular pathogenesis to therapeutic perspectives. Front Neuroendocrinol 2020; 57:100821. [PMID: 32006533 DOI: 10.1016/j.yfrne.2020.100821] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 11/19/2022]
Abstract
The pleiotropic peptide insulin-like growth factor 1 (IGF-I) regulates human body homeostasis and cell growth. IGF-I activates two major signaling pathways, namely phosphoinositide-3-kinase (PI3K)/protein kinase B (PKB/Akt) and Ras/extracellular signal-regulated kinase (ERK), which contribute to brain development, metabolism and function as well as to neuronal maintenance and survival. In this review, we discuss the general and tissue-specific effects of the IGF-I pathways. In addition, we present a comprehensive overview examining the role of IGF-I in neurodegenerative diseases, such as spinal and muscular atrophy, amyotrophic lateral sclerosis, and polyglutamine diseases. In each disease, we analyze the disturbances of the IGF-I pathway, the modification of the disease protein by IGF-I signaling, and the therapeutic strategies based on the use of IGF-I developed to date. Lastly, we highlight present and future considerations in the use of IGF-I for the treatment of these disorders.
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Affiliation(s)
- Maria Pennuto
- Department of Biomedical Sciences (DBS), University of Padova, 35131 Padova, Italy; Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy; Padova Neuroscience Center (PNC), 35131 Padova, Italy; Myology Center (CIR-Myo), 35131 Padova, Italy.
| | - Udai Bhan Pandey
- Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15261, USA; Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA; Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - María José Polanco
- Department of Pharmaceutic and Health Science, University San Pablo CEU, Campus Montepríncipe, 28925 Alcorcón, Madrid, Spain.
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7
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Joustra SD, Roelfsema F, van Trotsenburg ASP, Schneider HJ, Kosilek RP, Kroon HM, Logan JG, Butterfield NC, Zhou X, Toufaily C, Bak B, Turgeon MO, Brûlé E, Steyn FJ, Gurnell M, Koulouri O, Le Tissier P, Fontanaud P, Duncan Bassett JH, Williams GR, Oostdijk W, Wit JM, Pereira AM, Biermasz NR, Bernard DJ, Schoenmakers N. IGSF1 Deficiency Results in Human and Murine Somatotrope Neurosecretory Hyperfunction. J Clin Endocrinol Metab 2020; 105:5606971. [PMID: 31650157 PMCID: PMC7108761 DOI: 10.1210/clinem/dgz093] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 10/03/2019] [Indexed: 12/11/2022]
Abstract
CONTEXT The X-linked immunoglobulin superfamily, member 1 (IGSF1), gene is highly expressed in the hypothalamus and in pituitary cells of the POU1F1 lineage. Human loss-of-function mutations in IGSF1 cause central hypothyroidism, hypoprolactinemia, and macroorchidism. Additionally, most affected adults exhibit higher than average IGF-1 levels and anecdotal reports describe acromegaloid features in older subjects. However, somatotrope function has not yet been formally evaluated in this condition. OBJECTIVE We aimed to evaluate the role of IGSF1 in human and murine somatotrope function. PATIENTS, DESIGN, AND SETTING We evaluated 21 adult males harboring hemizygous IGSF1 loss-of-function mutations for features of GH excess, in an academic clinical setting. MAIN OUTCOME MEASURES We compared biochemical and tissue markers of GH excess in patients and controls, including 24-hour GH profile studies in 7 patients. Parallel studies were undertaken in male Igsf1-deficient mice and wild-type littermates. RESULTS IGSF1-deficient adult male patients demonstrated acromegaloid facial features with increased head circumference as well as increased finger soft-tissue thickness. Median serum IGF-1 concentrations were elevated, and 24-hour GH profile studies confirmed 2- to 3-fold increased median basal, pulsatile, and total GH secretion. Male Igsf1-deficient mice also demonstrated features of GH excess with increased lean mass, organ size, and skeletal dimensions and elevated mean circulating IGF-1 and pituitary GH levels. CONCLUSIONS We demonstrate somatotrope neurosecretory hyperfunction in IGSF1-deficient humans and mice. These observations define a hitherto uncharacterized role for IGSF1 in somatotropes and indicate that patients with IGSF1 mutations should be evaluated for long-term consequences of increased GH exposure.
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Affiliation(s)
- Sjoerd D Joustra
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
- Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
- Correspondence and Reprint Requests: Nadia Schoenmakers, University of Cambridge Metabolic Research Laboratories, Level 4, Wellcome Trust-MRC Institute of Metabolic Science, Box 289, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ UK. E-mail:
| | - Ferdinand Roelfsema
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
| | - A S Paul van Trotsenburg
- Emma Children’s Hospital, Amsterdam UMC, University of Amsterdam, Pediatric Endocrinology, Amsterdam, Netherlands
| | - Harald J Schneider
- Department of Endocrinology, Ludwig-Maximilians University, Munich, Germany
| | - Robert P Kosilek
- Department of Endocrinology, Ludwig-Maximilians University, Munich, Germany
| | - Herman M Kroon
- Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - John G Logan
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London, UK
| | - Natalie C Butterfield
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London, UK
| | - Xiang Zhou
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Chirine Toufaily
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Beata Bak
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Marc-Olivier Turgeon
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Emilie Brûlé
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Frederik J Steyn
- The University of Queensland Centre for Clinical Research, Brisbane, Australia
| | - Mark Gurnell
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ UK
| | - Olympia Koulouri
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ UK
| | - Paul Le Tissier
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Pierre Fontanaud
- CNRS, Institut de Génomique Fonctionnelle, INSERM, and Université de Montpellier, Montpellier, France
| | - J H Duncan Bassett
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London, UK
| | - Graham R Williams
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London, UK
| | - Wilma Oostdijk
- Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
| | - Jan M Wit
- Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands
| | - Alberto M Pereira
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
| | - Nienke R Biermasz
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, Netherlands
| | - Daniel J Bernard
- Departments of Anatomy and Cell Biology & Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Nadia Schoenmakers
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ UK
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Nagel G, Peter RS, Rosenbohm A, Koenig W, Dupuis L, Rothenbacher D, Ludolph AC. Association of Insulin-like Growth Factor 1 Concentrations with Risk for and Prognosis of Amyotrophic Lateral Sclerosis - Results from the ALS Registry Swabia. Sci Rep 2020; 10:736. [PMID: 31959864 PMCID: PMC6971302 DOI: 10.1038/s41598-020-57744-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/20/2019] [Indexed: 11/09/2022] Open
Abstract
We investigated the associations of serum concentration of insulin-like growth factor 1 (IGF1) with risk and prognosis of ALS in the ALS registry (October 2010-June 2014, median follow-up 67.6 months) in a case-control and cohort study, respectively. Serum samples were measured for IGF-1. Information on covariates was collected by standardized questionnaire. We applied conditional logistic regression to appraise the risk and Cox proportional hazards models to appraise the prognostic value of IGF-1. Data of 294 ALS patients (mean age 65.4 (SD 11.0) years, 60.2% men) and 504 controls were included in the case-control study. Median serum IGF-1 concentrations were slightly higher in ALS cases than in controls (101 vs. 99.5 ng/ml). IGF-1 concentrations were not associated with ALS risk in the fully adjusted model (top vs. bottom quartile: OR 1.16; 95%-CI 0.73-1.84, p for trend = 0.44). Among 293 ALS cases (mean age 65.5 (SD 10.5) years, 56.8% men) 243 died during follow-up. We found a statistically significant inverse association between continuous IGF-1 concentrations and survival (p = 0.01). Very high values IGF-1 were associated with a better prognosis of ALS suggesting that functions related to IGF-1 could be involved in survival.
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Affiliation(s)
- Gabriele Nagel
- Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany
| | - Raphael S Peter
- Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany
| | | | - Wolfgang Koenig
- Deutsches Herzzentrum München, Technische Universität München, Munich, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany
| | - Luc Dupuis
- INSERM U1118, Université de Strasbourg, Strasbourg, France
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9
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Huang L, Huang Z, Chen C. Rhythmic growth hormone secretion in physiological and pathological conditions: Lessons from rodent studies. Mol Cell Endocrinol 2019; 498:110575. [PMID: 31499134 DOI: 10.1016/j.mce.2019.110575] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/04/2019] [Accepted: 09/04/2019] [Indexed: 02/01/2023]
Abstract
Evolutionally conserved in all mammalians, the release of GH occurs in a rhythmic pattern, characterized by several dominant surges (pulsatile GH) with tonic low inter-pulse levels (tonic GH). Such pulsatile secretion pattern is essential for many physiological actions of GH on different tissues with defined gender dimorphism. Rhythmic release of pulsatile GH is tightly controlled by hypothalamic neurons as well as peripheral metabolic factors. Changes of GH pattern occur within a range of sophisticated physiological and pathological settings and significantly contribute to growth, ageing, survival and disease predispositions. Precise analysis of GH secretion pattern is vitally important for a comprehensive understanding of the function of GH and the components that regulate GH secretion pattern.
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Affiliation(s)
- Lili Huang
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, Australia
| | - Zhengxiang Huang
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, Australia
| | - Chen Chen
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, Australia.
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10
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Halon-Golabek M, Borkowska A, Kaczor JJ, Ziolkowski W, Flis DJ, Knap N, Kasperuk K, Antosiewicz J. hmSOD1 gene mutation-induced disturbance in iron metabolism is mediated by impairment of Akt signalling pathway. J Cachexia Sarcopenia Muscle 2018; 9:557-569. [PMID: 29380557 PMCID: PMC5989766 DOI: 10.1002/jcsm.12283] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/13/2017] [Accepted: 12/19/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Recently, skeletal muscle atrophy, impairment of iron metabolism, and insulin signalling have been reported in rats suffering from amyotrophic lateral sclerosis (ALS). However, the interrelationship between these changes has not been studied. We hypothesize that an impaired Akt-FOXO3a signalling pathway triggers changes in the iron metabolism in the muscles of transgenic animals. METHODS In the present study, we used transgenic rats bearing the G93A hmSOD1 gene and their non-transgenic littermates. The study was performed on the muscles taken from animals at three different stages of the disease: asymptomatic (ALS I), the onset of the disease (ALS II), and the terminal stage of the disease (ALS III). In order to study the molecular mechanism of changes in iron metabolism, we used SH-SY5Y and C2C12 cell lines stably transfected with pcDNA3.1, SOD1 WT and SOD1 G93A, or FOXO3a TM-ER. RESULTS A significant decrease in P-Akt level and changes in iron metabolism were observed even in the group of ALS I animals. This was accompanied by an increase in the active form of FOXO3a, up-regulation of atrogin-1, and catalase. However, significant muscle atrophy was observed in ALS II animals. An increase in ferritin L and H was accompanied by a rise in PCBP1 and APP protein levels. In SH-SY5Y cells stably expressing SOD1 or SOD1 G93A, we observed elevated levels of ferritin L and H and non-haem iron. Interestingly, insulin treatment significantly down-regulated ferritin L and H proteins in the cell. Conversely, cells transfected with small interfering RNA against Akt 1, 2, 3, respectively, showed a significant increase in the ferritin and FOXO3a levels. In order to assess the role of FOXO3a in the ferritin expression, we constructed a line of SH-SY5Y cells that expressed a fusion protein made of FOXO3a fused at the C-terminus with the ligand-binding domain of the oestrogen receptor (TM-ER) being activated by 4-hydroxytamoxifen. Treatment of the cells with 4-hydroxytamoxifen significantly up-regulated ferritin L and H proteins level. CONCLUSIONS Our data suggest that impairment of insulin signalling and iron metabolism in the skeletal muscle precedes muscle atrophy and is mediated by changes in Akt/FOXO3a signalling pathways.
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Affiliation(s)
| | - Andzelika Borkowska
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, 80-211, Poland
| | - Jan J Kaczor
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, 80-211, Poland.,Department of Neurobiology of Muscle, Gdansk University of Physical Education and Sport, Gdansk, 80-336, Poland
| | - Wieslaw Ziolkowski
- Department of Bioenergetics and Nutrition, Gdansk University of Physical Education and Sport, Gdansk, 80-336, Poland
| | - Damian J Flis
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, 80-211, Poland.,Department of Bioenergetics and Nutrition, Gdansk University of Physical Education and Sport, Gdansk, 80-336, Poland
| | - Narcyz Knap
- Department of Medical Chemistry, Medical University of Gdansk, Gdansk, 80-211, Poland
| | - Kajetan Kasperuk
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, 80-211, Poland
| | - Jedrzej Antosiewicz
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, 80-211, Poland.,Department of Biochemistry, Gdansk University of Physical Education and Sport, Gdansk, 80-336, Poland
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11
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Bianchi VE, Locatelli V, Rizzi L. Neurotrophic and Neuroregenerative Effects of GH/IGF1. Int J Mol Sci 2017; 18:ijms18112441. [PMID: 29149058 PMCID: PMC5713408 DOI: 10.3390/ijms18112441] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 12/12/2022] Open
Abstract
Introduction. Human neurodegenerative diseases increase progressively with age and present a high social and economic burden. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are both growth factors exerting trophic effects on neuronal regeneration in the central nervous system (CNS) and peripheral nervous system (PNS). GH and IGF-1 stimulate protein synthesis in neurons, glia, oligodendrocytes, and Schwann cells, and favor neuronal survival, inhibiting apoptosis. This study aims to evaluate the effect of GH and IGF-1 on neurons, and their possible therapeutic clinical applications on neuron regeneration in human subjects. Methods. In the literature, we searched the clinical trials and followed up studies in humans, which have evaluated the effect of GH/IGF-1 on CNS and PNS. The following keywords have been used: “GH/IGF-1” associated with “neuroregeneration”, “amyotrophic lateral sclerosis”, “Alzheimer disease”, “Parkinson’s disease”, “brain”, and “neuron”. Results. Of the retrieved articles, we found nine articles about the effect of GH in healthy patients who suffered from traumatic brain injury (TBI), and six studies (four using IGF-1 and two GH therapy) in patients with amyotrophic lateral sclerosis (ALS). The administration of GH in patients after TBI showed a significantly positive recovery of brain and mental function. Treatment with GH and IGF-1 therapy in ALS produced contradictory results. Conclusions. Although strong findings have shown the positive effects of GH/IGF-1 administration on neuroregeneration in animal models, a very limited number of clinical studies have been conducted in humans. GH/IGF-1 therapy had different effects in patients with TBI, evidencing a high recovery of neurons and clinical outcome, while in ALS patients, the results are contradictory. More complex clinical protocols are necessary to evaluate the effect of GH/IGF-1 efficacy in neurodegenerative diseases. It seems evident that GH and IGF-1 therapy favors the optimal recovery of neurons when a consistent residual activity is still present. Furthermore, the effect of GH/IGF-1 could be mediated by, or be overlapped with that of other hormones, such as estradiol and testosterone.
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Affiliation(s)
- Vittorio Emanuele Bianchi
- Endocrinology and Metabolism, Clinical Center Stella Maris, Strada Rovereta, 42-47891 Falciano, San Marino.
| | - Vittorio Locatelli
- School of Medicine and Surgery, University of Milano-Bicocca via Cadore, 48-20900 Monza Brianza, Italy.
| | - Laura Rizzi
- Molecular Biology, School of Medicine and Surgery, University of Milano-Bicocca, via Cadore, 48-20900 Monza Brianza, Italy.
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12
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Bozzoni V, Pansarasa O, Diamanti L, Nosari G, Cereda C, Ceroni M. Amyotrophic lateral sclerosis and environmental factors. FUNCTIONAL NEUROLOGY 2016; 31:7-19. [PMID: 27027889 DOI: 10.11138/fneur/2016.31.1.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that affects central and peripheral motor neuron cells. Its etiology is unknown, although a relationship between genetic background and environmental factors may play a major role in triggering the neurodegeneration. In this review, we analyze the role of environmental factors in ALS: heavy metals, electromagnetic fields and electric shocks, pesticides, β-N-methylamino-L-alanine, physical activity and the controversial role of sports. The literature on the single issues is analyzed in an attempt to clarify, as clearly as possible, whether each risk factor significantly contributes to the disease pathogenesis. After summarizing conflicting observations and data, the authors provide a final synthetic statement.
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13
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Triheptanoin Protects Motor Neurons and Delays the Onset of Motor Symptoms in a Mouse Model of Amyotrophic Lateral Sclerosis. PLoS One 2016; 11:e0161816. [PMID: 27564703 PMCID: PMC5001695 DOI: 10.1371/journal.pone.0161816] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 08/14/2016] [Indexed: 12/12/2022] Open
Abstract
There is increasing evidence that energy metabolism is disturbed in Amyotrophic Lateral Sclerosis (ALS) patients and animal models. Treatment with triheptanoin, the triglyceride of heptanoate, is a promising approach to provide alternative fuel to improve oxidative phosphorylation and aid ATP generation. Heptanoate can be metabolized to propionyl-CoA, which after carboxylation can produce succinyl-CoA and thereby re-fill the tricarboxylic acid (TCA) cycle (anaplerosis). Here we tested the hypothesis that treatment with triheptanoin prevents motor neuron loss and delays the onset of disease symptoms in female mice overexpressing the mutant human SOD1G93A (hSOD1G93A) gene. When oral triheptanoin (35% of caloric content) was initiated at P35, motor neuron loss at 70 days of age was attenuated by 33%. In untreated hSOD1G93A mice, the loss of hind limb grip strength began at 16.7 weeks. Triheptanoin maintained hind limb grip strength for 2.8 weeks longer (p<0.01). Loss of balance on the rotarod and reduction of body weight were delayed by 13 and 11 days respectively (both p<0.01). Improved motor function occurred in parallel with alterations in the expression of genes associated with muscle metabolism. In gastrocnemius muscles, the mRNA levels of pyruvate, 2-oxoglutarate and succinate dehydrogenases and methyl-malonyl mutase were reduced by 24–33% in 10 week old hSOD1G93A mice when compared to wild-type mice, suggesting that TCA cycling in skeletal muscle may be slowed in this ALS mouse model at a stage when muscle strength is still normal. At 25 weeks of age, mRNA levels of succinate dehydrogenases, glutamic pyruvic transaminase 2 and the propionyl carboxylase β subunit were reduced by 69–84% in control, but not in triheptanoin treated hSOD1G93A animals. Taken together, our results suggest that triheptanoin slows motor neuron loss and the onset of motor symptoms in ALS mice by improving TCA cycling.
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14
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Ngo S, Steyn F, McCombe P. Body mass index and dietary intervention: Implications for prognosis of amyotrophic lateral sclerosis. J Neurol Sci 2014; 340:5-12. [DOI: 10.1016/j.jns.2014.02.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 12/12/2022]
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15
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Steyn FJ, Lee K, Fogarty MJ, Veldhuis JD, McCombe PA, Bellingham MC, Ngo ST, Chen C. Growth hormone secretion is correlated with neuromuscular innervation rather than motor neuron number in early-symptomatic male amyotrophic lateral sclerosis mice. Endocrinology 2013; 154:4695-706. [PMID: 24108071 DOI: 10.1210/en.2013-1570] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
GH deficiency is thought to be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). However, therapy with GH and/or IGF-I has not shown benefit. To gain a better understanding of the role of GH secretion in ALS pathogenesis, we assessed endogenous GH secretion in wild-type and hSOD1(G93A) mice throughout the course of ALS disease. Male wild-type and hSOD1(G93A) mice were studied at the presymptomatic, onset, and end stages of disease. To assess the pathological features of disease, we measured motor neuron number and neuromuscular innervation. We report that GH secretion profile varies at different stages of disease progression in hSOD1(G93A) mice; compared with age-matched controls, GH secretion is unchanged prior to the onset of disease symptoms, elevated at the onset of disease symptoms, and reduced at the end stage of disease. In hSOD1(G93A) mice at the onset of disease, GH secretion is positively correlated with the percentage of neuromuscular innervation but not with motor neuron number. Moreover, this occurs in parallel with an elevation in the expression of muscle IGF-I relative to controls. Our data imply that increased GH secretion at symptom onset may be an endogenous endocrine response to increase the local production of muscle IGF-I to stimulate reinnervation of muscle, but that in the latter stages of disease this response no longer occurs.
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Affiliation(s)
- F J Steyn
- School of Biomedical Sciences, University of Queensland, St Lucia 4072, Australia. ; or Prof Chen Chen, School of Biomedical Sciences, University of Queensland, St Lucia 4072, Australia. E-mail:
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16
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Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. Amyotroph Lateral Scler Frontotemporal Degener 2013. [DOI: 10.3109/21678421.2013.838413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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17
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Tan HY, Huang L, Simmons D, Veldhuis JD, Steyn FJ, Chen C. Hypothalamic distribution of somatostatin mRNA expressing neurones relative to pubertal and adult changes in pulsatile growth hormone secretion in mice. J Neuroendocrinol 2013; 25:910-9. [PMID: 23855876 DOI: 10.1111/jne.12078] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 01/03/2023]
Abstract
The age-associated decline in growth hormone (GH) secretion may be a consequence of the reduction in the number of GH-releasing hormone (GHRH) positive neurones. However, it remains unclear whether an alteration in the number or distribution of somatostatin (SST) neurones contributes to this change. In the present study, we characterised the role of SST in modulating the change in pulsatile GH secretion in male C57Bl/6J mice throughout puberty and into early adulthood. We assessed pulsatile GH secretion in mice at 4, 8 and 16 weeks of age. These ages correspond to early pubertal, early adulthood and adulthood, respectively. We show an elevation in peak, total and pulsatile GH secretion coinciding with periods of rapid linear growth. Using in situ hybridisation and morphometric methods, we mapped the distribution of Sst mRNA expression within the mouse brain relative to this change in pulsatile GH secretion. The results obtained show that altered pulsatile GH secretion in male mice from 4-16 weeks of age does not coincide with a significant change in the number of Sst mRNA expressing neurones or an abundance of Sst mRNA expression throughout the arcuate nucleus (ARC) and periventricular nucleus (PeV). Rather, we observed a progressive decline in Sst mRNA expressing neurones within subnuclei of the paraventricular nucleus at this time. We conclude that structural changes in Sst expression within the PeV and ARC may not reflect the observed decline in pulsatile GH secretion in mice from puberty into early adulthood.
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Affiliation(s)
- H Y Tan
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
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18
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Steyn FJ, Xie TY, Huang L, Ngo ST, Veldhuis JD, Waters MJ, Chen C. Increased adiposity and insulin correlates with the progressive suppression of pulsatile GH secretion during weight gain. J Endocrinol 2013; 218:233-44. [PMID: 23708999 DOI: 10.1530/joe-13-0084] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Pathological changes associated with obesity are thought to contribute to GH deficiency. However, recent observations suggest that impaired GH secretion relative to excess calorie consumption contributes to progressive weight gain and thus may contribute to the development of obesity. To clarify this association between adiposity and GH secretion, we investigated the relationship between pulsatile GH secretion and body weight; epididymal fat mass; and circulating levels of leptin, insulin, non-esterified free fatty acids (NEFAs), and glucose. Data were obtained from male mice maintained on a standard or high-fat diet. We confirm the suppression of pulsatile GH secretion following dietary-induced weight gain. Correlation analyses reveal an inverse relationship between measures of pulsatile GH secretion, body weight, and epididymal fat mass. Moreover, we demonstrate an inverse relationship between measures of pulsatile GH secretion and circulating levels of leptin and insulin. The secretion of GH did not change relative to circulating levels of NEFAs or glucose. We conclude that impaired pulsatile GH secretion in the mouse occurs alongside progressive weight gain and thus precedes the development of obesity. Moreover, data illustrate key interactions between GH secretion and circulating levels of insulin and reflect the potential physiological role of GH in modulation of insulin-induced lipogenesis throughout positive energy balance.
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Affiliation(s)
- F J Steyn
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
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19
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Huang L, Steyn FJ, Tan HY, Xie TY, Veldhuis JD, Ngo ST, Chen C. The decline in pulsatile GH secretion throughout early adulthood in mice is exacerbated by dietary-induced weight gain. Endocrinology 2012; 153:4380-8. [PMID: 22802464 DOI: 10.1210/en.2012-1178] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The transition between puberty and adulthood is accompanied by a slowing in linear growth. Although GH is a key factor that drives somatic development into adulthood, early adulthood coincides with a reduction in circulating levels of GH. To this extent, a pathological decline in postpubertal GH secretion is detrimental to attainment of peak lean muscle mass and bone mass and promotes adiposity and increases susceptibility to the development of obesity in adulthood. Here we characterized pulsatile GH secretion in C57BL/6J mice at 12 and 16 wk of age. Deconvolution analysis of these measures reveals a reduction in pulsatile GH secretion between 12 and 16 wk of age. Dietary intervention with high-fat feeding at 8 wk of age results in a significant increase in adiposity, the development of glucose intolerance, and hyperinsulinemia. We show the exacerbation of the age-associated decline in pulsatile GH secretion in high-fat-fed mice after 4 wk of dietary intervention (at 12 wk of age), and a further suppression of pulsatile GH secretion by 8 wk of dietary intervention (at 16 wk of age). Suppressed pulsatile secretion of GH did not coincide with an elevation in circulating free fatty acids. Rather, we observed increased hepatic triglyceride content and an eventual decrease in circulating levels of IGF-I. Given the established role of GH in maintaining healthy aging, we anticipate that an advancing of the age-associated decline in pulsatile GH secretion as a consequence of dietary-induced weight gain may have long-term ramifications on adult health.
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Affiliation(s)
- L Huang
- School of Biomedical Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia
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