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Fernandes JDL, Perazzo MF, Paiva SM, Martins-Júnior PA, Macari S. Orthodontic treatment during pregnancy, lactation, and postmenopausal period: a questionnaire development. Braz Oral Res 2024; 38:e013. [PMID: 38198311 DOI: 10.1590/1807-3107bor-2024.vol38.0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 02/13/2023] [Indexed: 01/12/2024] Open
Abstract
This study aimed to develop and validate a self-administered questionnaire in Brazilian Portuguese to verify the level of knowledge of orthodontists in the care of pregnant, lactating, and postmenopausal women, named "Considerations on Orthodontic Treatment during Pregnancy, Lactation, and Postmenopausal Periods." The development and validation of the questionnaire consisted of the following steps: a) item generation; b) item reduction; c) questionnaire design; and d) validity and reliability tests in a cross-sectional study with 258 orthodontists working in the field from different Brazilian states. A total of 60 orthodontists participated in test-retest over a mean period of 45 days. The preliminary questionnaire consisted of a total of 60 questions. After item reduction, 40 questions were selected for the final version of the questionnaire, with eight questions about pregnant women; six about lactating women; 18 about postmenopausal women, and eight about general knowledge in dentistry. Each item had three response options in the Likert scale format. Face and content validity analysis, reliability assessment through internal consistency (Cronbach's alpha and McDonald's omega), and test-retest reliability through the intraclass correlation coefficient (ICC) and Spearman's correlation coefficient were performed. Face and content validity indicated that the questionnaire was considered valid, objective, and easily understandable. The questionnaire had good internal consistency (Cronbach's alpha = 0.77; McDonald's omega = 0.78) and good test-retest reliability (ICC = 0.71; Spearman's correlation coefficient = 0.51). The questionnaire was considered valid and reliable to assess the level of knowledge of orthodontists in the care of pregnant, lactating, and postmenopausal women.
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Affiliation(s)
- Juliana de Lourdes Fernandes
- Universidade Federal de Minas Gerais - UFMG, School of Dentistry, Department of Restorative Dentistry, Belo Horizonte, MG, Brazil
| | - Matheus França Perazzo
- Universidade Federal de Minas Gerais - UFMG, School of Dentistry, Department of Oral Health of Children and Adolescents, Belo Horizonte, MG, Brazil
| | - Saul Martins Paiva
- Universidade Federal de Minas Gerais - UFMG, School of Dentistry, Department of Oral Health of Children and Adolescents, Belo Horizonte, MG, Brazil
| | - Paulo Antônio Martins-Júnior
- Universidade Federal de Minas Gerais - UFMG, School of Dentistry, Department of Oral Health of Children and Adolescents, Belo Horizonte, MG, Brazil
| | - Soraia Macari
- Universidade Federal de Minas Gerais - UFMG, School of Dentistry, Department of Restorative Dentistry, Belo Horizonte, MG, Brazil
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2
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Fricke HP, Hernandez LL. The Serotonergic System and Bone Metabolism During Pregnancy and Lactation and the Implications of SSRI Use on the Maternal-Offspring Dyad. J Mammary Gland Biol Neoplasia 2023; 28:7. [PMID: 37086330 PMCID: PMC10122632 DOI: 10.1007/s10911-023-09535-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/06/2023] [Indexed: 04/23/2023] Open
Abstract
Lactation is a physiological adaptation of the class Mammalia and is a product of over 200 million years of evolution. During lactation, the mammary gland orchestrates bone metabolism via serotonin signaling in order to provide sufficient calcium for the offspring in milk. The role of serotonin in bone remodeling was first discovered over two decades ago, and the interplay between serotonin, lactation, and bone metabolism has been explored in the years following. It is estimated that postpartum depression affects 10-15% of the population, and selective serotonin reuptake inhibitors (SSRI) are often used as the first-line treatment. Studies conducted in humans, nonhuman primates, sheep, and rodents have provided evidence that there are consequences on both parent and offspring when serotonin signaling is disrupted during the peripartal period; however, the long-term consequences of disruption of serotonin signaling via SSRIs during the peripartal period on the maternal and offspring skeleton are not fully known. This review will focus on the relationship between the mammary gland, serotonin, and bone remodeling during the peripartal period and the skeletal consequences of the dysregulation of the serotonergic system in both human and animal studies.
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Affiliation(s)
- Hannah P Fricke
- Animal and Dairy Sciences Department, University of Wisconsin-Madison, Madison, WI, USA
| | - Laura L Hernandez
- Animal and Dairy Sciences Department, University of Wisconsin-Madison, Madison, WI, USA.
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3
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Brent MB. Pharmaceutical treatment of bone loss: From animal models and drug development to future treatment strategies. Pharmacol Ther 2023; 244:108383. [PMID: 36933702 DOI: 10.1016/j.pharmthera.2023.108383] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/18/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023]
Abstract
Animal models are fundamental to advance our knowledge of the underlying pathophysiology of bone loss and to study pharmaceutical countermeasures against it. The animal model of post-menopausal osteoporosis from ovariectomy is the most widely used preclinical approach to study skeletal deterioration. However, several other animal models exist, each with unique characteristics such as bone loss from disuse, lactation, glucocorticoid excess, or exposure to hypobaric hypoxia. The present review aimed to provide a comprehensive overview of these animal models to emphasize the importance and significance of investigating bone loss and pharmaceutical countermeasures from perspectives other than post-menopausal osteoporosis only. Hence, the pathophysiology and underlying cellular mechanisms involved in the various types of bone loss are different, and this might influence which prevention and treatment strategies are the most effective. In addition, the review sought to map the current landscape of pharmaceutical countermeasures against osteoporosis with an emphasis on how drug development has changed from being driven by clinical observations and enhancement or repurposing of existing drugs to today's use of targeted anti-bodies that are the result of advanced insights into the underlying molecular mechanisms of bone formation and resorption. Moreover, new treatment combinations or repurposing opportunities of already approved drugs with a focus on dabigatran, parathyroid hormone and abaloparatide, growth hormone, inhibitors of the activin signaling pathway, acetazolamide, zoledronate, and romosozumab are discussed. Despite the considerable progress in drug development, there is still a clear need to improve treatment strategies and develop new pharmaceuticals against various types of osteoporosis. The review also highlights that new treatment indications should be explored using multiple animal models of bone loss in order to ensure a broad representation of different types of skeletal deterioration instead of mainly focusing on primary osteoporosis from post-menopausal estrogen deficiency.
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Affiliation(s)
- Mikkel Bo Brent
- Department of Biomedicine, Aarhus University, Denmark, Wilhelm Meyers Allé 3, 8000 Aarhus C, Denmark.
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4
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Athonvarangkul D, Wysolmerski JJ. Crosstalk within a brain-breast-bone axis regulates mineral and skeletal metabolism during lactation. Front Physiol 2023; 14:1121579. [PMID: 36875035 PMCID: PMC9979219 DOI: 10.3389/fphys.2023.1121579] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/27/2023] [Indexed: 02/18/2023] Open
Abstract
To support the increased calcium demands for milk production during lactation, a dramatic and reversible physiological response occurs to alter bone and mineral metabolism. This coordinated process involves a brain-breast-bone axis that integrates hormonal signals that allow for adequate calcium delivery to milk yet also protects the maternal skeletal from excessive bone loss or decreases in bone quality or function. Here, we review the current knowledge on the crosstalk between the hypothalamus, mammary gland, and skeleton during lactation. We discuss the rare entity of pregnancy and lactation associated osteoporosis and consider how the physiology of bone turnover in lactation may impact the pathophysiology of postmenopausal osteoporosis. Further understanding of the regulators of bone loss during lactation, particularly in humans, may provide insights into new therapies for osteoporosis and other diseases of excess bone loss.
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Affiliation(s)
- Diana Athonvarangkul
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
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5
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Lykking EK, Kammerlander H, van Dijk FS, Prieto-Alhambra D, Abrahamsen B, Folkestad L. Fractures following pregnancy in Osteogenesis imperfecta - A self-controlled case series using Danish Health Registers. Bone 2022; 154:116177. [PMID: 34508880 DOI: 10.1016/j.bone.2021.116177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/23/2021] [Accepted: 09/04/2021] [Indexed: 11/26/2022]
Abstract
Osteogenesis imperfecta (OI) is a rare inherited connective tissue disorder with considerable clinical and genetic heterogeneity. The clinical hallmark of OI is liability to fractures due to reduced bone strength. Pregnancy and lactation are periods of increased calcium demand resulting in a decrease in maternal bone mineral density (BMD). This self-controlled case series evaluates fracture risk 12- and 19-months prior to conception compared to a period of 12- and 19 months following childbirth in women with OI. This study is based on data from the Danish National Patient Register collected between 1995 and 2018. Modified Poisson models were fitted to estimate Incidence Rate Ratio in the post/pre-pregnancy period/s, adjusted by parity and age. The 12-month observation group included 111 women with 205 pregnancies, and the 19-month observation 108 women with 197 pregnancies. We calculated fracture rates (IR) of 48.78 [95%CI 18.55-79.01] per 1000 person years 12 months prior to conception, and of 27.87 [95%CI 10.60-45.14] in the 12 months post-delivery. Comparing pre- and post-pregnancy period we found an incidence rate ratio (IRR) of 1.00 [95%CI 0.42-2.40]. When adjusting for parity and age at delivery no significant change in the IRR was noted. In the 19 months observation-period, the IR per 1000 person years prior to conception was 74.84 [95%CI 44.25-105.43] and the IR postpartum was 36.86 [95%CI 17.55-56.17], leading to an IRR of 0.61 [95%CI 0.31-1.18]. We could not identify any increased risk of fractures when comparing fracture rates during pregnancy and 12 or 19 months postpartum to fracture rates 12 or 19 months prior to conception.
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Affiliation(s)
- Emilie Karense Lykking
- Department of Endocrinology, Odense University Hospital, Odense, Denmark; Institute of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Heidi Kammerlander
- Department of Gynecology and Obstetrics, Lillebælt Hospital Kolding, Denmark
| | - Fleur S van Dijk
- North West Thames Regional Genetics Service, London North West Health Care University NHS Trust, Harrow, UK; Department of Metabolism, Digestion and Reproduction, Section of Genetics and Genomics, Imperial College London, London, UK
| | - Daniel Prieto-Alhambra
- Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK
| | - Bo Abrahamsen
- Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK; Department of Medicine, Holbæk Hospital, Holbæk, Denmark; Open Data Explorative Network, University of Southern Denmark, Odense, Denmark
| | - Lars Folkestad
- Department of Endocrinology, Odense University Hospital, Odense, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
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Li Y, de Bakker CMJ, Lai X, Zhao H, Parajuli A, Tseng WJ, Pei S, Meng T, Chung R, Wang L, Liu XS. Maternal bone adaptation to mechanical loading during pregnancy, lactation, and post-weaning recovery. Bone 2021; 151:116031. [PMID: 34098162 PMCID: PMC8504362 DOI: 10.1016/j.bone.2021.116031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/25/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022]
Abstract
The maternal skeleton undergoes dramatic bone loss during pregnancy and lactation, and substantial bone recovery post-weaning. The structural adaptations of maternal bone during reproduction and lactation exert a better protection of the mechanical integrity at the critical load-bearing sites, suggesting the importance of physiological load-bearing in regulating reproduction-induced skeletal alterations. Although it is suggested that physical exercise during pregnancy and breastfeeding improves women's physical and psychological well-being, its effects on maternal bone health remain unclear. Therefore, the objective of this study was to investigate the maternal bone adaptations to external mechanical loading during pregnancy, lactation, and post-weaning recovery. By utilizing an in vivo dynamic tibial loading protocol in a rat model, we demonstrated improved maternal cortical bone structure in response to dynamic loading at tibial midshaft, regardless of reproductive status. Notably, despite the minimal loading responses detected in the trabecular bone in virgins, rat bone during lactation experienced enhanced mechano-responsiveness in both trabecular and cortical bone compartments when compared to rats at other reproductive stages or age-matched virgins. Furthermore, our study showed that the lactation-induced elevation in osteocyte peri-lacunar/canalicular remodeling (PLR) activities led to enlarged osteocyte lacunae. This may result in alterations in interstitial fluid flow-mediated mechanical stimulation on osteocytes and an elevation in solute transport through the lacunar-canalicular system (LCS) during high-frequency dynamic loading, thus enhancing mechano-responsiveness of maternal bone during lactation. Taken together, findings from this study provide important insights into the relationship between reproduction- and lactation-induced skeletal changes and external mechanical loading, emphasizing the importance of weight-bearing exercise on maternal bone health during reproduction and postpartum.
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Affiliation(s)
- Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Chantal M J de Bakker
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Department of Radiology, Cumming School of Medicine, McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada
| | - Xiaohan Lai
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Hongbo Zhao
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ashutosh Parajuli
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Wei-Ju Tseng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Shaopeng Pei
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Tan Meng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Rebecca Chung
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Liyun Wang
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
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7
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Camerino C. Oxytocin Involvement in Body Composition Unveils the True Identity of Oxytocin. Int J Mol Sci 2021; 22:ijms22126383. [PMID: 34203705 PMCID: PMC8232088 DOI: 10.3390/ijms22126383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/28/2021] [Accepted: 05/29/2021] [Indexed: 01/11/2023] Open
Abstract
The origin of the Oxytocin/Vasopressin system dates back about 600 million years. Oxytocin (Oxt) together with Vasopressin (VP) regulate a diversity of physiological functions that are important for osmoregulation, reproduction, metabolism, and social behavior. Oxt/VP-like peptides have been identified in several invertebrate species and they are functionally related across the entire animal kingdom. Functional conservation enables future exploitation of invertebrate models to study Oxt’s functions not related to pregnancy and the basic mechanisms of central Oxt/VP signaling. Specifically, Oxt is well known for its effects on uteri contractility and milk ejection as well as on metabolism and energy homeostasis. Moreover, the striking evidence that Oxt is linked to energy regulation is that Oxt- and Oxytocin receptor (Oxtr)-deficient mice show late onset obesity. Interestingly Oxt−/− or Oxtr−/− mice develop weight gain without increasing food intake, suggesting that a lack of Oxt reduce metabolic rate. Oxt is expressed in a diversity of skeletal muscle phenotypes and regulates thermogenesis and bone mass. Oxt may increases skeletal muscle tonicity and/or increases body temperature. In this review, the author compared the three most recent theories on the effects of Oxt on body composition.
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Affiliation(s)
- Claudia Camerino
- Department of Biomedical Sciences and Human Oncology (Section of Pharmacology), School of Medicine, University of Bari Aldo Moro, P.za G. Cesare 11, 70100 Bari, Italy;
- Department of Physiology and Pharmacology “V. Erspamer”, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
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8
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Yu M, Pal S, Paterson CW, Li JY, Tyagi AM, Adams J, Coopersmith CM, Weitzmann MN, Pacifici R. Ovariectomy induces bone loss via microbial-dependent trafficking of intestinal TNF+ T cells and Th17 cells. J Clin Invest 2021; 131:143137. [PMID: 33586672 PMCID: PMC7880410 DOI: 10.1172/jci143137] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 12/01/2020] [Indexed: 02/06/2023] Open
Abstract
Estrogen deficiency causes a gut microbiome-dependent expansion of BM Th17 cells and TNF-α-producing T cells. The resulting increased BM levels of IL-17a (IL-17) and TNF stimulate RANKL expression and activity, causing bone loss. However, the origin of BM Th17 cells and TNF+ T cells is unknown. Here, we show that ovariectomy (ovx) expanded intestinal Th17 cells and TNF+ T cells, increased their S1P receptor 1-mediated (S1PR1-mediated) egress from the intestine, and enhanced their subsequent influx into the BM through CXCR3- and CCL20-mediated mechanisms. Demonstrating the functional relevance of T cell trafficking, blockade of Th17 cell and TNF+ T cell egress from the gut or their influx into the BM prevented ovx-induced bone loss. Therefore, intestinal T cells are a proximal target of sex steroid deficiency relevant for bone loss. Blockade of intestinal T cell migration may represent a therapeutic strategy for the treatment of postmenopausal bone loss.
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Affiliation(s)
- Mingcan Yu
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
| | - Subhashis Pal
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
| | - Cameron W. Paterson
- Department of Surgery and Emory Critical Care Center, Emory University School of Medicine, Atlanta, Georgia, USA
- Medical Corps, United States Navy, NROTC, Atlanta, Georgia, USA
| | - Jau-Yi Li
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
| | - Abdul Malik Tyagi
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
| | - Jonathan Adams
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
| | - Craig M. Coopersmith
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
- Department of Surgery and Emory Critical Care Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - M. Neale Weitzmann
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
- Atlanta VA Medical Center, Decatur, Georgia, USA
| | - Roberto Pacifici
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine and
- Emory Microbiome Research Center, Emory University, Atlanta, Georgia, USA
- Immunology and Molecular Pathogenesis Program, Emory University, Atlanta, Georgia, USA
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Jansen ID, Papapoulos SE, Bravenboer N, de Vries TJ, Appelman-Dijkstra NM. Increased Bone Resorption during Lactation in Pycnodysostosis. Int J Mol Sci 2021; 22:ijms22041810. [PMID: 33670411 PMCID: PMC7918824 DOI: 10.3390/ijms22041810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/04/2021] [Accepted: 02/07/2021] [Indexed: 12/03/2022] Open
Abstract
Pycnodysostosis, a rare autosomal recessive skeletal dysplasia, is caused by a deficiency of cathepsin K. Patients have impaired bone resorption in the presence of normal or increased numbers of multinucleated, but dysfunctional, osteoclasts. Cathepsin K degrades collagen type I and generates N-telopeptide (NTX) and the C-telopeptide (CTX) that can be quantified. Levels of these telopeptides are increased in lactating women and are associated with increased bone resorption. Nothing is known about the consequences of cathepsin K deficiency in lactating women. Here we present for the first time normalized blood and CTX measurements in a patient with pycnodysostosis, exclusively related to the lactation period. In vitro studies using osteoclasts derived from blood monocytes during lactation and after weaning further show consistent bone resorption before and after lactation. Increased expression of cathepsins L and S in osteoclasts derived from the lactating patient suggests that other proteinases could compensate for the lack of cathepsin K during the lactation period of pycnodysostosis patients.
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Affiliation(s)
- Ineke D.C. Jansen
- Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands; (I.D.C.J.); (T.J.d.V.)
| | - Socrates E. Papapoulos
- Center for Bone Quality Department of Internal Medicine division of Endocrinology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
| | - Nathalie Bravenboer
- Department of Clinical Chemistry, Amsterdam University Medical Center, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands;
| | - Teun J. de Vries
- Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands; (I.D.C.J.); (T.J.d.V.)
| | - Natasha M. Appelman-Dijkstra
- Center for Bone Quality Department of Internal Medicine division of Endocrinology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
- Correspondence:
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Lee SJ, Song SY, Rhee Y. Skeletal changes during lactation and after weaning in osteocyte-specific sclerostin overexpressed mice. J Bone Miner Metab 2020; 38:172-178. [PMID: 31501981 DOI: 10.1007/s00774-019-01044-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/14/2019] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Lactation inevitably leads to a state of rapid bone loss; however, maternal bone undergoes rapid remineralization after weaning. Sclerostin, encoded by the gene SOST, is exclusively secreted from osteocytes and plays important roles in bone remodeling. However, there are few studies about the effect of sclerostin during lactation and weaning on bone microstructures. Therefore, we conducted the study to demonstrate any possible association of sclerostin with bone metabolism and skeletal changes during lactation and after weaning. MATERIALS AND METHODS We analyzed bone mineral density (BMD) by dual-energy X-ray absorptiometry at the spine and femur, bone microstructure by micro-computed tomography (μCT) at the distal and mid-shaft of the femur and biochemical markers such as sclerostin and bone turnover markers at 1 week and 3 weeks of lactation and 2 weeks post-weaning in osteocyte-specific sclerostin-overexpressed transgenic mice, and compared them with wild type. RESULTS Lactation significantly resulted in decreased spine and femur BMD at day 7 and day 21 of breastfeeding; specifically, cortical microstructure (cross-sectional thickness and cross-sectional area) at the mid-shaft of the femur had significantly deteriorated. At day 14 after weaning, femur BMD and cortical microstructure at the mid-shaft of the femur in both the wild and DMP-SOST mice had incompletely recovered; however, spine BMD and trabecular microstructures at the distal femur recovered in wild type mice. CONCLUSIONS Sclerostin, secreted by osteocytes, played a role in bone loss during lactation and also in the recovery of trabecular bone compartment by activating bone formation after weaning.
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Affiliation(s)
- Su Jin Lee
- Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
- Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Sun Yong Song
- Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Yumie Rhee
- Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.
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Abstract
The primitive neurohypophyseal nonapeptide oxytocin (OXT) has established functions in parturition, lactation, appetite, and social behavior. We have shown that OXT has direct actions on the mammalian skeleton, stimulating bone formation by osteoblasts and modulating the genesis and function of bone-resorbing osteoclasts. We deleted OXT receptors (OXTRs) selectively in osteoblasts and osteoclasts using Col2.3Cre and Acp5Cre mice, respectively. Both male and female Col2.3Cre + :Oxtr fl/fl mice recapitulate the low-bone mass phenotype of Oxtr +/- mice, suggesting that OXT has a prominent osteoblastic action in vivo. Furthermore, abolishment of the anabolic effect of estrogen in Col2.3Cre + :Oxtr fl/fl mice suggests that osteoblastic OXTRs are necessary for estrogen action. In addition, the high bone mass in Acp5Cre + :Oxtr fl/fl mice indicates a prominent action of OXT in stimulating osteoclastogenesis. In contrast, we found that in pregnant and lactating Col2.3Cre + :Oxtr fl/fl mice, elevated OXT inhibits bone resorption and rescues the bone loss otherwise noted during pregnancy and lactation. However, OXT does not contribute to ovariectomy-induced bone loss. Finally, we show that OXT acts directly on OXTRs on adipocytes to suppress the white-to-beige transition gene program. Despite this direct antibeiging action, injected OXT reduces total body fat, likely through an action on OXT-ergic neurons. Consistent with an antiobesity action of OXT, Oxt -/- and Oxtr -/- mice display increased total body fat. Overall, the actions of OXT on bone mass and body composition provide the framework for future therapies for osteoporosis and obesity.
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12
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Liu XS, Wang L, de Bakker CMJ, Lai X. Mechanical Regulation of the Maternal Skeleton during Reproduction and Lactation. Curr Osteoporos Rep 2019; 17:375-386. [PMID: 31755029 PMCID: PMC7373497 DOI: 10.1007/s11914-019-00555-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an effort to elucidate how the balance between the structural and metabolic functions of the skeleton is achieved during these physiological processes. RECENT FINDINGS While pregnancy and lactation induce significant changes in bone density and structure to provide calcium for fetal/infant growth, the maternal physiology also comprises several innate compensatory mechanisms that allow for the maintenance of skeletal mechanical integrity. Both clinical and animal studies suggest that pregnancy and lactation lead to adaptations in cortical bone structure to allow for rapid calcium release from the trabecular compartment while maintaining whole bone stiffness and strength. Moreover, extents of lactation-induced bone loss and weaning-induced recovery are highly dependent on a given bone's load-bearing function, resulting in better protection of the mechanical integrity at critical load-bearing sites. The recent discovery of lactation-induced osteocytic perilacunar/canalicular remodeling (PLR) indicates a new means for osteocytes to modulate mineral homeostasis and tissue-level mechanical properties of the maternal skeleton. Furthermore, lactation-induced PLR may also play an important role in maintaining the maternal skeleton's load-bearing capacity by altering osteocyte's microenvironment and modulating the transmission of anabolic mechanical signals to osteocytes. Both clinical and animal studies show that parity and lactation have no adverse, or a positive effect on bone strength later in life. The skeletal effects during pregnancy and lactation reflect an optimized balance between the mechanical and metabolic functions of the skeleton.
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Affiliation(s)
- X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 332A Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA, USA.
| | - Liyun Wang
- Center for Biomechanical Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Chantal M J de Bakker
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Xiaohan Lai
- School of Life Sciences, University of Science and Technology of China, Hefei, China
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13
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Canul-Medina G, Fernandez-Mejia C. Morphological, hormonal, and molecular changes in different maternal tissues during lactation and post-lactation. J Physiol Sci 2019; 69:825-835. [PMID: 31564033 PMCID: PMC10717399 DOI: 10.1007/s12576-019-00714-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 09/13/2019] [Indexed: 12/21/2022]
Abstract
Milk supply and quality during lactation are critical for progeny survival. Maternal tissues and metabolism, influenced by hormonal changes, undergo modification during lactation to sustain breastfeeding. Two organs that suffer essential adjustment are the mammary glands and the bone; however, renal calcium conservation and calcium absorption from the intestine are also modified. Lactation leads to a transient loss of bone minerals to provide adequate amounts of minerals, including calcium for milk production. Physiological, metabolic, and molecular changes in different tissues participate in providing nutrients for milk production. After weaning, the histological, metabolic, and hormonal modifications that take place in lactation are reverted, and bone remineralization is a central function at this time. This study focuses on the hormonal, metabolic, molecular, and tissue modifications that occur in mammary glands, bone, intestine, and kidneys in the mother during lactation and post-weaning periods.
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Affiliation(s)
- Gustavo Canul-Medina
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México/Instituto Nacional de Pediatría, Av. del Iman #1, 4th Floor, 04530, Mexico City, Mexico
| | - Cristina Fernandez-Mejia
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México/Instituto Nacional de Pediatría, Av. del Iman #1, 4th Floor, 04530, Mexico City, Mexico.
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14
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Olvera D, Stolzenfeld R, Fisher E, Nolan B, Caird MS, Kozloff KM. Pamidronate Administration During Pregnancy and Lactation Induces Temporal Preservation of Maternal Bone Mass in a Mouse Model of Osteogenesis Imperfecta. J Bone Miner Res 2019; 34:2061-2074. [PMID: 31310351 PMCID: PMC6854294 DOI: 10.1002/jbmr.3831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/25/2019] [Accepted: 07/03/2019] [Indexed: 01/25/2023]
Abstract
During pregnancy and lactation, the maternal skeleton undergoes significant bone loss through increased resorption to provide the necessary calcium supply to the developing fetus and suckling neonate. This period of skeletal vulnerability has not been clearly associated with increased maternal fracture risk, but these physiological conditions can exacerbate an underlying metabolic bone condition like osteogenesis imperfecta. Although bisphosphonates (BPs) are commonly used in postmenopausal women, there are cases where premenopausal women taking BPs become pregnant. Given BPs' long half-life, there is a need to establish how BPs affect the maternal skeleton during periods of demanding metabolic bone changes that are critical for the skeletal development of their offspring. In the present study, pamidronate- (PAM-) amplified pregnancy-induced bone mass gains and lactation-induced bone loss were prevented. This preservation of bone mass was less robust when PAM was administered at late stages of lactation compared with early pregnancy and first day of lactation. Pregnancy-induced osteocyte osteolysis was also observed and was unaffected with PAM treatment. No negative skeletal effects were observed in offspring from PAM-treated dams despite lactation-induced bone loss prevention. These findings provide important insight into (1) a treatment window for when PAM is most effective in preserving maternal bone mass, and (2) the maternal changes in bone metabolism that maintain calcium homeostasis crucial for fetal and neonatal bone development. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Diana Olvera
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Rachel Stolzenfeld
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Emily Fisher
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Bonnie Nolan
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Michelle S Caird
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Kenneth M Kozloff
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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15
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Lotinun S, Ishihara Y, Nagano K, Kiviranta R, Carpentier VT, Neff L, Parkman V, Ide N, Hu D, Dann P, Brooks D, Bouxsein ML, Wysolmerski J, Gori F, Baron R. Cathepsin K-deficient osteocytes prevent lactation-induced bone loss and parathyroid hormone suppression. J Clin Invest 2019; 129:3058-3071. [PMID: 31112135 DOI: 10.1172/jci122936] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Lactation induces bone loss to provide sufficient calcium in the milk, a process that involves osteoclastic bone resorption but also osteocytes and perilacunar resorption. The exact mechanisms by which osteocytes contribute to bone loss remain elusive. Osteocytes express genes required in osteoclasts for bone resorption, including cathepsin K (Ctsk), and lactation elevates their expression. We show that Ctsk deletion in osteocytes prevented the increase in osteocyte lacunar area seen during lactation, as well as the effects of lactation to increase osteoclast numbers and decrease trabecular bone volume, cortical thickness and mechanical properties. In addition, Ctsk deletion in osteocytes increased bone Parathyroid Hormone related Peptide (PTHrP), prevented the decrease in serum Parathyroid Hormone (PTH) induced by lactation, but amplified the increase in serum 1,25(OH)2D. The net result of these changes is to maintain serum and milk calcium levels in the normal range, ensuring normal offspring skeletal development. Our studies confirm the fundamental role of osteocytic perilacunar remodeling in physiological states of lactation and provides genetic evidence that osteocyte-derived Ctsk contributes not only to osteocyte perilacunar remodeling, but also to the regulation of PTH, PTHrP, 1,25-Dyhydroxyvitamin D (1,25(OH)2D), osteoclastogenesis and bone loss in response to the high calcium demand associated with lactation.
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Affiliation(s)
- Sutada Lotinun
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA.,Department of Physiology and Skeletal Disorders Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Yoshihito Ishihara
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Kenichi Nagano
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Riku Kiviranta
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA.,Departments of Medical Biochemistry and Genetics and Medicine, University of Turku, Turku, Finland
| | - Vincent T Carpentier
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Lynn Neff
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Virginia Parkman
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Noriko Ide
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Dorothy Hu
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Pamela Dann
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Daniel Brooks
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Mary L Bouxsein
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - John Wysolmerski
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Francesca Gori
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Roland Baron
- Division of Bone and Mineral Research, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA.,Harvard Medical School, Department of Medicine, Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts, USA
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16
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Teerapornpuntakit J, Chanprapaph P, Charoenphandhu N. Previous Adolescent Pregnancy and Breastfeeding Does Not Negatively Affect Bone Mineral Density at the Age of Peak Bone Mass. Breastfeed Med 2018; 13:500-505. [PMID: 30156423 DOI: 10.1089/bfm.2018.0080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To determine bone mineral density (BMD) at the age of peak bone mass in women who previously experienced pregnancy and breastfeeding during adolescence. MATERIALS AND METHODS In this retrospective study, female volunteers aged 24-30 years who were pregnant during the age of 15-19 years and have had one to two babies were recruited. All of them experienced breastfeeding without history of bone- or calcium-related problems, such as fracture or low calcium intake. BMD was determined at the femur and L1-L4 spine by dual-energy X-ray absorptiometry. RESULTS We found that both volunteers who previously experienced breastfeeding and age-matched control volunteers had similar BMD at the L1-L4 spines and femora. Further analysis for site-specific changes of lumbar and femoral BMDs showed that the values of the breastfeeding group were not different from those of the control group except at L1 and L2, where BMD values were greater in breastfeeding group compared with the control group. At both femoral and vertebral sites, T- and Z-scores were apparently similar between the two groups. In addition, the BMD at peak bone mass had no significant correlation with breastfeeding duration. CONCLUSIONS Teenage pregnancy and breastfeeding did not negatively affect BMD later at the age of peak bone mass. Therefore, breastfeeding can be encouraged in teenage mothers.
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Affiliation(s)
- Jarinthorn Teerapornpuntakit
- 1 Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University , Bangkok, Thailand .,2 Department of Physiology, Faculty of Medical Science, Naresuan University , Phitsanulok, Thailand
| | - Pharuhas Chanprapaph
- 3 Department of Obstetrics and Gynaecology, Faculty of Medicine Siriraj Hospital, Mahidol University , Bangkok, Thailand
| | - Narattaphol Charoenphandhu
- 1 Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University , Bangkok, Thailand .,4 Department of Physiology, Faculty of Science, Mahidol University , Bangkok, Thailand .,5 Institute of Molecular Biosciences, Mahidol University , Nakhon Pathom, Thailand .,6 The Academy of Science , The Royal Society of Thailand, Dusit, Bangkok, Thailand
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17
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Tsourdi E, Jähn K, Rauner M, Busse B, Bonewald LF. Physiological and pathological osteocytic osteolysis. JOURNAL OF MUSCULOSKELETAL & NEURONAL INTERACTIONS 2018; 18:292-303. [PMID: 30179206 PMCID: PMC6146198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Osteocytes, the most abundant bone cell in the adult skeleton, can function as mechanosensors directing osteoblast and osteoclast function in order to maintain optimal load bearing bone in addition to functioning as endocrine cells regulating phosphate metabolism. A controversial function, previously overlooked or denied, has been osteocytes as regulators of calcium metabolism. Early histologists upon observing enlarged osteocyte lacunae in bone sections proposed that mature osteocytes could remove their perilacunar matrix, a term called "osteocytic osteolysis". New insights into this process have occurred during the last decade using novel technology thereby providing a means to identify molecular mechanisms responsible for osteocytic osteolysis. As release of calcium from a mineralized matrix requires a more acidic pH and specialized enzymes, it was proposed that osteocytes may utilize similar molecular mechanisms as osteoclasts to remove mineral. The idea that a cell descended from mesenchymal progenitors (the osteocyte) could function similarly to a cell descended from hematopoietic progenitors (the osteoclast) was challenged as being improbable. Here we review the molecular mechanisms behind this osteocyte function, the role of osteocytic osteolysis in health and disease, and the capacity of the osteocyte to reverse the osteolytic process by replacing the removed matrix, a revived osteoblast function.
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Affiliation(s)
- Elena Tsourdi
- Department of Medicine III, Technische Universität Dresden Medical Center, Dresden, Germany,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany,Corresponding author: Elena Tsourdi, M.D., Division of Endocrinology, Diabetes and Metabolic Bone Diseases, Department of Medicine III, Technische Universität Dresden Medical Center, Fetscherstrasse 74, 01307 Dresden, Germany E-mail:
| | - Katharina Jähn
- Department for Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Martina Rauner
- Department of Medicine III, Technische Universität Dresden Medical Center, Dresden, Germany,Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Björn Busse
- Department for Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lynda F. Bonewald
- Indiana Center for Musculoskeletal Health, VanNuys Medical Science Building, Indianapolis, USA
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18
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Weaver SR, Fricke HP, Xie C, Lipinski RJ, Vezina CM, Charles JF, Hernandez LL. Peripartum Fluoxetine Reduces Maternal Trabecular Bone After Weaning and Elevates Mammary Gland Serotonin and PTHrP. Endocrinology 2018; 159:2850-2862. [PMID: 29893816 PMCID: PMC6456925 DOI: 10.1210/en.2018-00279] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/04/2018] [Indexed: 12/28/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) have been linked to osteopenia and fracture risk; however, their long-term impact on bone health is not well understood. SSRIs are widely prescribed to pregnant and breastfeeding women who might be at particular risk of bone pathology because lactation is associated with considerable maternal bone loss. We used microCT and molecular approaches to test whether the SSRI fluoxetine, administered to C57BL/6 mice from conception through the end of lactation, causes persistent maternal bone loss. We found that peripartum fluoxetine increases serum calcium and reduces circulating markers of bone formation during lactation but does not affect osteoclastic resorption. Peripartum fluoxetine exposure also enhances mammary gland endocrine function during lactation by increasing synthesis of serotonin and PTHrP, a hormone that liberates calcium for milk synthesis and reduces bone mineral volume. Peripartum fluoxetine exposure reduces the trabecular bone volume fraction at 3 months after weaning. These findings raise new questions about the long-term consequences of peripartum SSRI use on maternal health.
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Affiliation(s)
- Samantha R Weaver
- Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin
| | - Hannah P Fricke
- Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin
| | - Cynthia Xie
- Department of Orthopedics, Brigham and Women’s Hospital, Boston, Massachusetts
- Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
| | - Robert J Lipinski
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Chad M Vezina
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Julia F Charles
- Department of Orthopedics, Brigham and Women’s Hospital, Boston, Massachusetts
- Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
| | - Laura L Hernandez
- Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin
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19
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Weaver SR, Hernandez LL. Could use of Selective Serotonin Reuptake Inhibitors During Lactation Cause Persistent Effects on Maternal Bone? J Mammary Gland Biol Neoplasia 2018; 23:5-25. [PMID: 29603039 DOI: 10.1007/s10911-018-9390-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/13/2018] [Indexed: 02/07/2023] Open
Abstract
The lactating mammary gland elegantly coordinates maternal homeostasis to provide calcium for milk. During lactation, the monoamine serotonin regulates the synthesis and release of various mammary gland-derived factors, such as parathyroid hormone-related protein (PTHrP), to stimulate bone resorption. Recent evidence suggests that bone mineral lost during prolonged lactation is not fully recovered following weaning, possibly putting women at increased risk of fracture or osteoporosis. Selective Serotonin Reuptake Inhibitor (SSRI) antidepressants have also been associated with reduced bone mineral density and increased fracture risk. Therefore, SSRI exposure while breastfeeding may exacerbate lactational bone loss, compromising long-term bone health. Through an examination of serotonin and calcium homeostasis during lactation, lactational bone turnover and post-weaning recovery of bone mineral, and the effect of peripartum depression and SSRI on the mammary gland and bone, this review will discuss the hypothesis that peripartum SSRI exposure causes persistent reductions in bone mineral density through mammary-derived PTHrP signaling with bone.
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Affiliation(s)
- Samantha R Weaver
- Endocrine and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Laura L Hernandez
- Department of Dairy Science, University of Wisconsin-Madison, Madison, WI, USA.
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20
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Gu A, Sellamuthu R, Himes E, Childress PJ, Pelus LM, Orschell CM, Kacena MA. Alterations to maternal cortical and trabecular bone in multiparous middle-aged mice. JOURNAL OF MUSCULOSKELETAL & NEURONAL INTERACTIONS 2017; 17:312-318. [PMID: 29199192 PMCID: PMC5749039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES During the reproductive cycle, altered calcium homeostasis is observed due to variable demand for mineral requirements. This results in increased bone resorption during the time period leading up to parturition and subsequent lactation. During lactation, women will lose 1-3% of bone mineral density per month, which is comparable to the loss experienced on an annual basis post-menopausal. The purpose of this study was to determine the effect of parity on bone formation in middle-aged mice. METHODS Mice were mated and grouped by number of parity and compared with age matched nulliparous controls. Measurements were taken of femoral trabecular and cortical bone. Calcium, protein and alkaline phosphatase levels were also measured. RESULTS An increase in trabecular bone mineral density was observed when comparing mice that had undergone parity once to the nulliparous control. An overall decrease in trabecular bone mineral density was observed as parity increased from 1 to 5 pregnancies. No alteration was seen in cortical bone formation. No difference was observed when calcium, protein and alkaline phosphatase levels were assessed. CONCLUSIONS This study demonstrates that number of parity has an impact on trabecular bone formation in middle-aged mice, with substantial changes in bone density seen among the parous groups.
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Affiliation(s)
- Alex Gu
- George Washington School of Medicine and Health Sciences, 2300 Eye Street NW, Washington DC 20037,Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis IN 46202,Corresponding author: Alex Gu, George Washington School of Medicine and Health Sciences, 2300 Eye Street NW, Washington DC 20037, United States E-mail:
| | - Rajendran Sellamuthu
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN, 46202
| | - Evan Himes
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis IN 46202
| | - Paul J. Childress
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis IN 46202
| | - Louis M. Pelus
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis IN 46202
| | - Christie M. Orschell
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN, 46202
| | - Melissa A. Kacena
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis IN 46202
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21
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Jähn K, Kelkar S, Zhao H, Xie Y, Tiede-Lewis LM, Dusevich V, Dallas SL, Bonewald LF. Osteocytes Acidify Their Microenvironment in Response to PTHrP In Vitro and in Lactating Mice In Vivo. J Bone Miner Res 2017; 32:1761-1772. [PMID: 28470757 PMCID: PMC5550338 DOI: 10.1002/jbmr.3167] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/04/2017] [Accepted: 05/01/2017] [Indexed: 11/10/2022]
Abstract
Osteocytes appear to mobilize calcium within minutes in response to PTH injections; we have previously shown that osteocytes remove their perilacunar matrix during lactation through activation of the PTH type 1 receptor. Mechanisms utilized by osteocytes to mobilize calcium are unknown but we hypothesized that the molecular components may be similar to those used by osteoclasts. Here we show, using IDG-SW3 cells that ATP6V0D2, an essential component of vacuolar ATPase in osteoclasts, and other genes associated with osteoclastic bone resorption, increase with osteoblast to osteocyte differentiation. Furthermore, PTHrP increases ATP6V0D2 expression and induces proton generation by primary osteocytes, which is blocked by bafilomycin, a vacuolar ATPase inhibitor. These in vitro proton measurements raised the question of osteocyte viability in an acidic environment. Interestingly, osteocytes, showed enhanced viability at pH as low as 5 compared to osteoblasts and fibroblasts in vitro. To study in vivo acidification by osteocytes, virgin and lactating CD1 mice on a low calcium diet were injected with the pH indicator dye, acridine orange, and their osteocyte lacuno-canalicular system imaged by confocal microscopy. Lower pH was observed in lactating compared to virgin animals. In addition, a novel transgenic mouse line with a topaz variant of green fluorescent protein (GFPtpz)-tagged collagen α2(I) chain was used. Instead of the expected reduction in GFP-fluorescence only in the perilacunar matrix, reduced fluorescence was observed in the entire bone matrix of lactating mice. Based on our experiments showing quenching of GFP in vitro, we propose that the observed reduction in GFP fluorescence in lactating mice is due to quenching of GFP by the acidic pH generated by osteocytes. Together these findings provide novel mechanistic insight into how osteocytes remove calcium from their perilacunar/pericanalicular matrices through active acidification of their microenvironment and show that osteocytes, like osteoclasts, are resistant to the negative effects of acid on viability. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Katharina Jähn
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Shilpa Kelkar
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Hong Zhao
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Yixia Xie
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - LeAnn M Tiede-Lewis
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Vladimir Dusevich
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Sarah L Dallas
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Lynda F Bonewald
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
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22
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Shamsuzzaman S, Onal M, St John HC, Pike JW. Deletion of a Distal RANKL Gene Enhancer Delays Progression of Atherosclerotic Plaque Calcification in Hypercholesterolemic Mice. J Cell Biochem 2017; 118:4240-4253. [PMID: 28419519 DOI: 10.1002/jcb.26074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 12/18/2022]
Abstract
Receptor activator of NF-κB ligand (RANKL) is a TNF-like cytokine which mediates diverse physiological functions including bone remodeling and immune regulation. RANKL has been identified in atherosclerotic lesions; however, its role in atherosclerotic plaque development remains elusive. An enhancer located 75 kb upstream of the murine Rankl gene's transcription start site designated D5 is important for its calciotropic hormone- and cytokine-mediated expression. Here, we determined the impact of RANKL levels in atherosclerotic plaque development in the D5 enhancer-null (D5-/- ) mice in an atherogenic Apoe-/- background fed a high-fat diet (HFD). Rankl mRNA transcripts were increased in aortic arches and thoracic aortae of Apoe-/- mice; however, this increase was blunted in Apoe-/- ;D5-/- mice. Similarly, higher Rankl transcripts were identified in splenic T lymphocytes in Apoe-/- mice, and their levels were reduced in Apoe-/- ;D5-/- mice. When analyzed by micro-computed tomography (µCT), atherosclerotic plaque calcification was identified in six out of eight Apoe-/- mice, whereas only one out of eight Apoe-/- ;D5-/- mice developed plaque calcification after 12 weeks of HFD. However, following 18 weeks of HFD challenge, all of Apoe-/- and Apoe-/- ;D5-/- animals developed atherosclerotic plaque calcification. Likewise, atherosclerotic lesion sizes were site-specifically reduced in the aortic arch of Apoe-/- ;D5-/- mice at initial stage of atherosclerosis and this effect was diminished as atherosclerosis proceeded to a more advanced stage. Our data suggest that deletion of the RANKL D5 enhancer delays the progression of atherosclerotic plaque development and plaque calcification in hypercholesterolemic mice. This work provides important insight into RANKL's regulatory role in atherosclerosis. J. Cell. Biochem. 118: 4240-4253, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Sohel Shamsuzzaman
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Melda Onal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - Hillary C St John
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706
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Du Y, Liu H, Yang Q, Wang S, Wang J, Ma J, Noh I, Mikos AG, Zhang S. Selective laser sintering scaffold with hierarchical architecture and gradient composition for osteochondral repair in rabbits. Biomaterials 2017; 137:37-48. [PMID: 28528301 DOI: 10.1016/j.biomaterials.2017.05.021] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/11/2017] [Accepted: 05/12/2017] [Indexed: 02/03/2023]
Abstract
Osteochondral defects cannot be adequately self-repaired due to the presence of the sophisticated hierarchical structure and the lack of blood supply in cartilage. Thus, one of the major challenges remaining in this field is the structural design of a biomimetic scaffold that satisfies the specific requirements for osteochondral repair. To address this hurdle, a bio-inspired multilayer osteochondral scaffold that consisted of the poly(ε-caprolactone) (PCL) and the hydroxyapatite (HA)/PCL microspheres, was constructed via selective laser sintering (SLS) technique. The SLS-derived scaffolds exhibited an excellent biocompatibility to support cell adhesion and proliferation in vitro. The repair effect was evaluated by implanting the acellular multilayer scaffolds into osteochondral defects of a rabbit model. Our findings demonstrated that the multilayer scaffolds were able to induce articular cartilage formation by accelerating the early subchondral bone regeneration, and the newly formed tissues could well integrate with the native tissues. Consequently, the current study not only achieves osteochondral repair, but also suggests a promising strategy for the fabrication of bio-inspired multilayer scaffolds with well-designed architecture and gradient composition via SLS technique.
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Affiliation(s)
- Yingying Du
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Haoming Liu
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Qin Yang
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Shuai Wang
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Jianglin Wang
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Jun Ma
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Insup Noh
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology, Nowon-gu, Seoul 139-743, Republic of Korea
| | - Antonios G Mikos
- Department of Bioengineering, Rice University, P.O. Box 1892, MS-142, Houston, TX 77251-1892, USA.
| | - Shengmin Zhang
- Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan 430074, PR China; Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.
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de Bakker CM, Altman-Singles AR, Li Y, Tseng WJ, Li C, Liu XS. Adaptations in the Microarchitecture and Load Distribution of Maternal Cortical and Trabecular Bone in Response to Multiple Reproductive Cycles in Rats. J Bone Miner Res 2017; 32:1014-1026. [PMID: 28109138 PMCID: PMC5537002 DOI: 10.1002/jbmr.3084] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/09/2017] [Accepted: 01/19/2017] [Indexed: 12/15/2022]
Abstract
Pregnancy, lactation, and weaning result in dramatic changes in maternal calcium metabolism. In particular, the increased calcium demand during lactation causes a substantial degree of maternal bone loss. This reproductive bone loss has been suggested to be largely reversible, as multiple clinical studies have found that parity and lactation history have no adverse effect on postmenopausal fracture risk. However, the precise effects of pregnancy, lactation, and post-weaning recovery on maternal bone structure are not well understood. Our study aimed to address this question by longitudinally tracking changes in trabecular and cortical bone microarchitecture at the proximal tibia in rats throughout three cycles of pregnancy, lactation, and post-weaning using in vivo μCT. We found that the trabecular thickness underwent a reversible deterioration during pregnancy and lactation, which was fully recovered after weaning, whereas other parameters of trabecular microarchitecture (including trabecular number, spacing, connectivity density, and structure model index) underwent a more permanent deterioration, which recovered minimally. Thus, pregnancy and lactation resulted in both transient and long-lasting alterations in trabecular microstructure. In the meantime, multiple reproductive cycles appeared to improve the robustness of cortical bone (resulting in an elevated cortical area and polar moment of inertia), as well as increase the proportion of the total load carried by the cortical bone at the proximal tibia. Taken together, changes in the cortical and trabecular compartments suggest that whereas rat tibial trabecular bone appears to be highly involved in maintaining calcium homeostasis during female reproduction, cortical bone adapts to increase its load-bearing capacity, allowing the overall mechanical function of the tibia to be maintained. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Chantal Mj de Bakker
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Allison R Altman-Singles
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Pennsylvania State University, Berks Campus, Reading, PA, USA
| | - Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Wei-Ju Tseng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Connie Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - X Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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25
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Kovacs CS. Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery. Physiol Rev 2016; 96:449-547. [PMID: 26887676 DOI: 10.1152/physrev.00027.2015] [Citation(s) in RCA: 251] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.
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Affiliation(s)
- Christopher S Kovacs
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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26
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Macica CM, King HE, Wang M, McEachon CL, Skinner CW, Tommasini SM. Novel anatomic adaptation of cortical bone to meet increased mineral demands of reproduction. Bone 2016; 85:59-69. [PMID: 26825813 PMCID: PMC7429445 DOI: 10.1016/j.bone.2015.12.056] [Citation(s) in RCA: 9] [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] [Received: 07/09/2015] [Revised: 12/14/2015] [Accepted: 12/18/2015] [Indexed: 12/27/2022]
Abstract
The goal of this study was to investigate the effects of reproductive adaptations to mineral homeostasis on the skeleton in a mouse model of compromised mineral homeostasis compared to adaptations in control, unaffected mice. During pregnancy, maternal adaptations to high mineral demand include more than doubling intestinal calcium absorption by increasing calcitriol production. However, calcitriol biosynthesis is impaired in HYP mice, a murine model of X-linked hypophosphatemia (XLH). In addition, there is a paucity of mineralized trabecular bone, a primary target of bone resorption during pregnancy and lactation. Because the highest density of mineral is in mature cortical bone, we hypothesized that mineral demand is met by utilizing intracortical mineral reserves. Indeed, analysis of HYP mice revealed dramatic increases in intracortical porosity characterized by elevated serum PTH and type-I collagen matrix-degrading enzyme MMP-13. We discovered an increase in carbonate ion substitution in the bone mineral matrix during pregnancy and lactation of HYP mice, suggesting an alternative mechanism of bone remodeling that maintains maternal bone mass during periods of high mineral demand. This phenomenon is not restricted to XLH, as increased carbonate in the mineral matrix also occurred in wild-type mice during lactation. Taken together, these data suggest that increased intracortical perilacunar mineral turnover also contributes to maintaining phosphate levels during periods of high mineral demand. Understanding the mechanisms of skeletal contribution to mineral homeostasis is important to improving the treatment and prevention of fracture risk and bone fragility for female patients with XLH, but also provides important insight into the role and unique adaptations of the maternal skeleton to the demands of fetal development and the needs of postnatal nutrition.
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Affiliation(s)
- Carolyn M Macica
- Department of Medical Sciences, Frank H. Netter, M.D., School of Medicine at Quinnipiac University, North Haven, CT 06518, United States.
| | - Helen E King
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520, United States; Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands.
| | - Meina Wang
- Department of Orthopaedics and Rehabilitation, Yale University, New Haven, CT 06520, United States.
| | - Courtney L McEachon
- Department of Orthopaedics and Rehabilitation, Yale University, New Haven, CT 06520, United States.
| | - Catherine W Skinner
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520, United States.
| | - Steven M Tommasini
- Department of Orthopaedics and Rehabilitation, Yale University, New Haven, CT 06520, United States.
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27
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Onal M, St John HC, Danielson AL, Markert JW, Riley EM, Pike JW. Unique Distal Enhancers Linked to the Mouse Tnfsf11 Gene Direct Tissue-Specific and Inflammation-Induced Expression of RANKL. Endocrinology 2016; 157:482-96. [PMID: 26646205 PMCID: PMC4733116 DOI: 10.1210/en.2015-1788] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Receptor activator of nuclear factor κB ligand (RANKL) is expressed by a number of cell types to participate in diverse physiological functions. We have previously identified 10 distal RANKL enhancers. Earlier studies have shown that RL-D5 is a multifunctional RANKL enhancer. Deletion of RL-D5 from the mouse genome leads to lower skeletal and lymphoid tissue RANKL, causing a high bone mass phenotype. Herein, we determine the physiological role and lineage specificity of 2 additional RANKL enhancers, RL-D6 and RL-T1, which are located 83 and 123 kb upstream of the gene's transcriptional start site, respectively. Lack of RL-D6 or RL-T1 did not alter skeletal RANKL or bone mineral density up to 48 weeks of age. Although both RL-D5 and RL-T1 contributed to activation induction of T-cell RANKL, RL-T1 knockout mice had drastically low lymphocyte and lymphoid tissue RANKL levels, indicating that RL-T1 is the major regulator of lymphocyte RANKL. Moreover, RL-T1 knockout mice had lower circulating soluble RANKL, suggesting that lymphocytes are important sources of circulating soluble RANKL. Under physiological conditions, lack of RL-D6 did not alter RANKL expression. However, lack of RL-D5 or RL-D6, but not of RL-T1, blunted the oncostatin M and lipopolysaccharide induction of RANKL ex vivo and in vivo, suggesting that RL-D5 and RL-D6 coregulate the inflammation-mediated induction of RANKL in osteocytes and osteoblasts while lack of RL-D6 did not alter secondary hyperparathyroidism or lactation induction of RANKL or bone loss. These results suggest that although RL-D5 mediates RANKL expression in multiple lineages, other cell type- or factor-specific enhancers are required for its appropriate control, demonstrating the cell type-specific and complex regulation of RANKL expression.
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Affiliation(s)
- M Onal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - H C St John
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - A L Danielson
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - J W Markert
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - E M Riley
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - J W Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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28
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Ohata Y, Ozono K, Michigami T. Current concepts in perinatal mineral metabolism. Clin Pediatr Endocrinol 2016; 25:9-17. [PMID: 26865750 PMCID: PMC4738188 DOI: 10.1297/cpe.25.9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/26/2015] [Indexed: 12/03/2022] Open
Abstract
The serum levels of calcium (Ca) and phosphate are maintained higher in the fetus than in
the pregnant mother, especially in late gestation, to meet the demands of fetal bone
development. In order to maintain this fetal stage-specific mineral homeostasis, the
placenta plays a critical role through active transcellular mineral transport. Although
the molecular mechanism of transplacental Ca transport has been well studied, little is
known about the transport mechanism of phosphate and magnesium. Maternal mineral
homeostasis is also altered during pregnancy to supply minerals to the fetus. In the
lactating mother, osteocytic osteolysis is suggested to be involved in the supply of
minerals to the baby. The levels of some calcitropic and phosphotropic (Ca- and
phosphate-regulating, respectively) hormones in the fetus are also different from those in
the adult. The PTH level in the fetus is lower than that in the mother and nonpregnant
adult. It is suggested, however, that low fetal PTH plays an important role in fetal
mineral metabolism. The concentration of PTHrP in the fetus is much higher than that of
PTH and plays a critical role in perinatal Ca homeostasis. Uncovering the molecular
mechanisms for fetal stage-specific mineral metabolism will lead to better management of
perinatal patients with mineral abnormalities.
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Affiliation(s)
- Yasuhisa Ohata
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan; Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
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Kovacs CS, Ralston SH. Presentation and management of osteoporosis presenting in association with pregnancy or lactation. Osteoporos Int 2015; 26:2223-41. [PMID: 25939309 DOI: 10.1007/s00198-015-3149-3] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 04/22/2015] [Indexed: 01/15/2023]
Abstract
In this review, we summarize our current understanding of the pathophysiology of fragility fractures that occur for the first time during pregnancy and lactation, and provide guidance on appropriate investigations and treatment strategies. Most affected women will have had no prior bone density reading, and so the extent of bone loss that may have occurred during pregnancy or lactation is uncertain. During pregnancy, intestinal calcium absorption doubles in order to meet the fetal demand for calcium, but if maternal intake of calcium is insufficient to meet the combined needs of the mother and baby, the maternal skeleton will undergo resorption during the third trimester. During lactation, several hormonal changes, independent of maternal calcium intake, program a 5-10 % loss of trabecular mineral content in order to provide calcium to milk. After weaning the baby, the maternal skeleton is normally restored to its prior mineral content and strength. This physiological bone resorption during reproduction does not normally cause fractures; instead, women who do fracture are more likely to have additional secondary causes of bone loss and fragility. Transient osteoporosis of the hip may affect one or both femoral heads during pregnancy but it involves localized edema and not skeletal resorption. Case reports have described the use of calcitonin, bisphosphonates, strontium ranelate, teriparatide, vertebroplasty, and kyphoplasty to treat post-partum vertebral fractures. However, the need for such treatments is uncertain given that a progressive increase in bone mass subsequently occurs in most women who present with a fracture during pregnancy or lactation.
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Affiliation(s)
- C S Kovacs
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada, A1B 3V6,
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Ardeshirpour L, Dumitru C, Dann P, Sterpka J, VanHouten J, Kim W, Kostenuik P, Wysolmerski J. OPG Treatment Prevents Bone Loss During Lactation But Does Not Affect Milk Production or Maternal Calcium Metabolism. Endocrinology 2015; 156:2762-73. [PMID: 25961842 PMCID: PMC4511126 DOI: 10.1210/en.2015-1232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Lactation is associated with increased bone turnover and rapid bone loss, which liberates skeletal calcium used for milk production. Previous studies suggested that an increase in the skeletal expression of receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells ligand (RANKL) coupled with a decrease in osteoprotegerin (OPG) levels likely triggered bone loss during lactation. In this study, we treated lactating mice with recombinant OPG to determine whether bone loss during lactation was dependent on RANKL signaling and whether resorption of the maternal skeleton was required to support milk production. OPG treatment lowered bone resorption rates and completely prevented bone loss during lactation but, surprisingly, did not decrease osteoclast numbers. In contrast, OPG was quite effective at lowering osteoblast numbers and inhibiting bone formation in lactating mice. Furthermore, treatment with OPG during lactation prevented the usual anabolic response associated with reversal of lactational bone loss after weaning. Preventing bone loss had no appreciable effect on milk production, milk calcium levels, or maternal calcium homeostasis when mice were on a standard diet. However, when dietary calcium was restricted, treatment with OPG caused maternal hypocalcemia, maternal death, and decreased milk production. These studies demonstrate that RANKL signaling is a requirement for bone loss during lactation, and suggest that osteoclast activity may be required to increase osteoblast numbers during lactation in preparation for the recovery of bone mass after weaning. These data also demonstrate that maternal bone loss is not absolutely required to supply calcium for milk production unless dietary calcium intake is inadequate.
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Affiliation(s)
- Laleh Ardeshirpour
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - Cristina Dumitru
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - Pamela Dann
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - John Sterpka
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - Joshua VanHouten
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - Wonnam Kim
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - Paul Kostenuik
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
| | - John Wysolmerski
- Section of Endocrinology (L.A.), Department of Pediatrics, and Section of Endocrinology and Metabolism (C.D., P.D., J.S., J.V., W.K., J.W.), Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06520; and Department of Metabolic Disorders (P.K.), Amgen, Inc, Thousand Oaks, California 91320
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Abstract
PURPOSE OF REVIEW To describe our current state of knowledge about the pathophysiology, incidence, and treatment of osteoporosis that presents during pregnancy, puerperium, and lactation. RECENT FINDINGS When vertebral fractures occur in pregnant or lactating women, it is usually unknown whether the skeleton was normal before pregnancy. Maternal adaptations increase bone resorption modestly during pregnancy but markedly during lactation. The net bone loss may occasionally precipitate fractures, especially in women who have underlying low bone mass or skeletal fragility prior to pregnancy. Bone mass and strength are normally restored postweaning. Transient osteoporosis of the hip is a sporadic disorder localized to one or both femoral heads; it is not due to generalized skeletal resorption. Anecdotal reports have used bisphosphonates, strontium ranelate, teriparatide, or vertebroplasty/kyphoplasty to treat postpartum vertebral fractures, but it is unclear whether these therapies had any added benefit over the spontaneous skeletal recovery that normally occurs after weaning. SUMMARY These relatively rare fragility fractures result from multifactorial causes, including skeletal disorders that precede pregnancy, and structural and metabolic stresses that can compromise skeletal strength during pregnancy and lactation. Further study is needed to determine when pharmacological or surgical therapy is warranted instead of conservative or expectant management.
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Affiliation(s)
- Christopher S Kovacs
- Faculty of Medicine - Endocrinology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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32
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Li H, Sun Y, Zheng H, Li L, Yu Q, Yao X. Parathyroid hormone-related protein overexpression protects goat mammary gland epithelial cells from calcium-sensing receptor activation-induced apoptosis. Mol Biol Rep 2014; 42:233-43. [DOI: 10.1007/s11033-014-3763-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 09/20/2014] [Indexed: 12/12/2022]
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Bornstein S, Brown SA, Le PT, Wang X, DeMambro V, Horowitz MC, MacDougald O, Baron R, Lotinun S, Karsenty G, Wei W, Ferron M, Kovacs CS, Clemmons D, Wan Y, Rosen CJ. FGF-21 and skeletal remodeling during and after lactation in C57BL/6J mice. Endocrinology 2014; 155:3516-26. [PMID: 24914939 PMCID: PMC4138567 DOI: 10.1210/en.2014-1083] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Lactation is associated with significant alterations in both body composition and bone mass. Systemic and local skeletal factors such as receptor activator of nuclear factor κ-B ligand (RANKL), PTHrP, calcitonin, and estrogen are known to regulate bone remodeling during and after lactation. Fibroblast growth factor 21 (FGF-21) may function as an endocrine factor to regulate body composition changes during lactation by inducing gluconeogenesis and fatty acid oxidation. In this study, we hypothesized that the metabolic changes during lactation were due in part to increased circulating FGF-21, which in turn could accentuate bone loss. We longitudinally characterized body composition in C57BL/6J (B6) mice during (day 7 and day 21 of lactation) and after normal lactation (day 21 postlactation). At day 7 of lactation, areal bone density declined by 10% (P < .001), bone resorption increased (P < .0001), percent fat decreased by 20%, energy expenditure increased (P < .01), and markers of brown-like adipogenesis were suppressed in the inguinal depot and in preformed brown adipose tissue. At day 7 of lactation there was a 2.4-fold increase in serum FGF-21 vs baseline (P < .0001), a 8-fold increase in hepatic FGF-21 mRNA (P < .03), a 2-fold increase in undercarboxylated osteocalcin (Glu13 OCn) (P < .01), and enhanced insulin sensitivity. Recovery of total areal bone density was noted at day 21 of lactation, whereas the femoral trabecular bone volume fraction was still reduced (P < .01). Because FGF-21 levels rose rapidly at day 7 of lactation in B6 lactating mice, we next examined lactating mice with a deletion in the Fgf21 gene. Trabecular and cortical bone masses were maintained throughout lactation in FGF-21(-/-) mice, and pup growth was normal. Compared with lactating control mice, lactating FGF-21(-/-) mice exhibited an increase in bone formation, but no change in bone resorption. In conclusion, in addition to changes in calciotropic hormones, systemic FGF-21 plays a role in skeletal remodeling and changes in body composition during lactation in B6 mice.
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Mamillapalli R, VanHouten J, Dann P, Bikle D, Chang W, Brown E, Wysolmerski J. Mammary-specific ablation of the calcium-sensing receptor during lactation alters maternal calcium metabolism, milk calcium transport, and neonatal calcium accrual. Endocrinology 2013; 154:3031-42. [PMID: 23782944 PMCID: PMC3749485 DOI: 10.1210/en.2012-2195] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate PTHrP secretion and milk calcium transport with calcium availability. To test this idea genetically, we bred BLG-Cre mice with CaSR-floxed mice to ablate the CaSR specifically from mammary epithelial cells only at the onset of lactation (CaSR-cKO mice). Loss of the CaSR in the lactating mammary gland did not disrupt alveolar differentiation or milk production. However, it did increase the secretion of PTHrP into milk and decreased the transport of calcium from the circulation into milk. CaSR-cKO mice did not show accelerated bone resorption, but they did have a decrease in bone formation. Loss of the mammary gland CaSR resulted in hypercalcemia, decreased PTH secretion, and increased renal calcium excretion in lactating mothers. Finally, loss of the mammary gland CaSR resulted in decreased calcium accrual by suckling neonates, likely due to the combination of increased milk PTHrP and decreased milk calcium. These results demonstrate that the mammary gland CaSR coordinates maternal bone and calcium metabolism, calcium transport into milk, and neonatal calcium accrual during lactation.
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Affiliation(s)
- Ramanaiah Mamillapalli
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, TAC S131, Box 208020, New Haven, Connecticut 06520-8020, USA
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Kirby BJ, Ma Y, Martin HM, Buckle Favaro KL, Karaplis AC, Kovacs CS. Upregulation of calcitriol during pregnancy and skeletal recovery after lactation do not require parathyroid hormone. J Bone Miner Res 2013; 28:1987-2000. [PMID: 23505097 DOI: 10.1002/jbmr.1925] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 02/16/2013] [Accepted: 03/04/2013] [Indexed: 12/14/2022]
Abstract
Pregnancy invokes a doubling of intestinal calcium absorption whereas lactation programs skeletal resorption to provide calcium to milk. Postweaning bone formation restores the skeleton's bone mineral content (BMC), but the factors that regulate this are not established. We used Pth-null mice to test whether parathyroid hormone (PTH) is required for postweaning skeletal recovery. On a normal 1% calcium diet, wild-type (WT) and Pth-null mice each gained BMC during pregnancy, declined 15% to 18% below baseline during lactation, and restored the skeleton above baseline BMC within 14 days postweaning. A 2% calcium diet reduced the lactational decline in BMC without altering the gains achieved during pregnancy and postweaning. The hypocalcemia and hyperphosphatemia of Pth-null mice normalized during lactation and serum calcium remained normal during postweaning. Osteocalcin and propeptide of type 1 collagen (P1NP) each rose significantly after lactation to similar values in WT and Pth-null. Serum calcitriol increased fivefold during pregnancy in both genotypes whereas vitamin D binding protein levels were unchanged. Absence of PTH blocked a normal rise in fibroblast growth factor-23 (FGF23) during pregnancy despite high calcitriol. A 30-fold higher expression of Cyp27b1 in maternal kidneys versus placenta suggests that the pregnancy-related increase in calcitriol comes from the kidneys. Conversely, substantial placental expression of Cyp24a1 may contribute significantly to the metabolism of calcitriol. In conclusion, PTH is not required to upregulate renal expression of Cyp27b1 during pregnancy or to stimulate recovery from loss of BMC caused by lactation. A calcium-rich diet in rodents suppresses skeletal losses during lactation, unlike clinical trials that showed no effect of supplemental calcium on lactational decline in BMC.
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Affiliation(s)
- Beth J Kirby
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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37
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Laporta J, Moore SAE, Peters MW, Peters TL, Hernandez LL. Short communication: Circulating serotonin (5-HT) concentrations on day 1 of lactation as a potential predictor of transition-related disorders. J Dairy Sci 2013; 96:5146-50. [PMID: 23746592 DOI: 10.3168/jds.2013-6718] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/24/2013] [Indexed: 11/19/2022]
Abstract
The monoamine serotonin (5-hydroxytryptamine; 5-HT) has been described as a homeostatic regulator of lactation. Recently, our laboratory determined that 5-HT is involved in the regulation of calcium and glucose homeostasis during the transition period in rodents. More specifically, we demonstrate that 5-HT is responsible for calcium mobilization from bone and upregulation of hepatic gluconeogenic enzymes and mammary gland glucose transporters. Our objective was to investigate the correlation between circulating 5-HT concentrations and circulating ionized calcium, parathyroid hormone-related protein (PTHrP), and glucose concentrations on d 1 postpartum. We also investigated the correlation between circulating 5-HT and milk fever and ketosis incidence and severity in multiparous Holstein cows at the onset of lactation. Blood samples were collected from 42 multiparous cows on d 1 of lactation and analyzed for 5-HT, calcium, glucose, and PTHrP. Milk fever (determined subjectively for each cow on d 1 postpartum) and ketosis incidence and severity (scale 1 to 4, determined objectively for each cow during the first 10 d postpartum) were recorded for all animals. Serum 5-HT was positively correlated with serum calcium and with plasma PTHrP (r>0.37). Serum 5-HT was negatively correlated with milk fever incidence and with ketosis severity (most severe ketosis incidence recorded during the first 10 d postpartum; r<-0.33). Serum calcium and plasma glucose concentrations were negatively correlated with milk fever and ketosis severity, respectively (r<-0.39). These data indicate that 5-HT potentially plays a role in the regulation of calcium and glucose homeostasis during the transition period in cattle, which we previously demonstrated in rodents. Increased circulating concentrations of 5-HT might decrease milk fever at the onset of lactation and ketosis severity during the first 10 d postpartum in dairy cows. Understanding this physiological axis could help describe the underlying mechanisms associated with these periparturient metabolic disorders in dairy cows.
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Affiliation(s)
- J Laporta
- Department of Dairy Science, University of Wisconsin, Madison, Wisconsin 53706, USA
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Wysolmerski JJ. Osteocytes remove and replace perilacunar mineral during reproductive cycles. Bone 2013; 54:230-6. [PMID: 23352996 PMCID: PMC3624069 DOI: 10.1016/j.bone.2013.01.025] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 12/05/2012] [Accepted: 01/11/2013] [Indexed: 11/16/2022]
Abstract
Lactation is associated with an increased demand for calcium and is accompanied by a remarkable cycle of bone loss and recovery that helps to supply calcium and phosphorus for milk production. Bone loss is the result of increased bone resorption that is due, in part, to increased levels of PTHrP and decreased levels of estrogen. However, the regulation of bone turnover during this time is not fully understood. In the 1960s and 1970s many observations were made to suggest that osteocytes could resorb bone and increase the size of their lacunae. This concept became known as osteocytic osteolysis and studies suggested that it occurred in response to parathyroid hormone and/or an increased systemic demand for calcium. However, this concept fell out of favor in the late 1970s when it was established that osteoclasts were the principal bone-resorbing cells. Given that lactation is associated with increased PTHrP levels and negative calcium balance, we recently examined whether osteocytes contribute to bone loss during this time. Our findings suggest that osteocytes can remodel their perilacunar and pericanalicular matrix and that they participate in the liberation of skeletal calcium stores during reproductive cycles. These findings raise new questions about the role of osteocytes in coordinating bone and mineral metabolism during lactation as well as the recovery of bone mass after weaning. It is also interesting to consider whether osteocyte lacunar and canalicular remodeling contribute more broadly to the maintenance of skeletal and mineral homeostasis.
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Affiliation(s)
- John J Wysolmerski
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, TAC S131, PO Box 208020, New Haven, CT 06520-8020, USA.
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Abstract
Normal breast epithelial cells and breast cancer cells express the calcium-sensing receptor (CaSR), the master regulator of systemic calcium metabolism. During lactation, activation of the CaSR in mammary epithelial cells downregulates parathyroid hormone-related protein (PTHrP) levels in milk and in the circulation, and increases calcium transport into milk. In contrast, in breast cancer cells the CaSR upregulates PTHrP production. A switch in G-protein usage underlies the opposing effects of the CaSR on PTHrP expression in normal and malignant breast cells. During lactation, the CaSR in normal breast cells coordinates a feedback loop that matches the transport of calcium into milk and maternal calcium metabolism to the supply of calcium. A switch in CaSR G-protein usage during malignant transformation converts this feedback loop into a feed-forward cycle in breast cancer cells that may promote the growth of osteolytic skeletal metastases.
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Affiliation(s)
- Joshua N Vanhouten
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, TAC S131, Box 208020, New Haven, CT, USA.
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40
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Osteocytic osteolysis: time for a second look? BONEKEY REPORTS 2012; 1:229. [PMID: 24363929 PMCID: PMC3868715 DOI: 10.1038/bonekey.2012.229] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/18/2012] [Accepted: 10/29/2012] [Indexed: 11/08/2022]
Abstract
Over 100 years ago it was suggested that osteocytes could remodel their surrounding environment by removing and replacing bone. In the 1960s and 1970s, many observations were made to suggest that osteocytes could resorb bone and increase the size of their lacunae. This concept became known as osteocytic osteolysis and studies suggested that it occurred in response to diverse stimuli such as parathyroid hormone, calcium restriction, hibernation and reproductive cycles. However, this concept fell out of favor in the late 1970s when it became clear that osteoclasts were the principal bone-resorbing cells in the skeleton. Over the past decade, we have increasingly appreciated that osteocytes are remarkably versatile cells and are involved in all aspects of skeletal biology, including the response to loading, the regulation of bone turnover and the control of mineral metabolism. Recent data have demonstrated that osteocytes remodel their perilacunar and canalicular matrix and participate in the liberation of skeletal calcium stores during lactation. In light of these new findings, it may be time to reassess the concept of osteocytic osteolysis and reconsider whether osteocyte lacunar and canalicular remodeling contributes more broadly to the maintenance of skeletal and mineral homeostasis.
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Qing H, Ardeshirpour L, Pajevic PD, Dusevich V, Jähn K, Kato S, Wysolmerski J, Bonewald LF. Demonstration of osteocytic perilacunar/canalicular remodeling in mice during lactation. J Bone Miner Res 2012; 27:1018-29. [PMID: 22308018 PMCID: PMC3770147 DOI: 10.1002/jbmr.1567] [Citation(s) in RCA: 338] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Osteoclasts are thought to be solely responsible for the removal of bone matrix. However, we show here that osteocytes can also remove bone matrix by reversibly remodeling their perilacunar/canalicular matrix during the reproductive cycle. In contrast, no osteocytic remodeling was observed with experimental unloading despite similar degrees of bone loss. Gene array analysis of osteocytes from lactating animals revealed an elevation of genes known to be utilized by osteoclasts to remove bone, including tartrate-resistant acid phosphatase (TRAP) and cathepsin K, that returned to virgin levels upon weaning. Infusion of parathyroid hormone-related peptide (PTHrP), known to be elevated during lactation, induced TRAP activity and cathepsin K expression in osteocytes concurrent with osteocytic remodeling. Conversely, animals lacking the parathyroid hormone type 1 receptor (PTHR1) in osteocytes failed to express TRAP or cathepsin K or to remodel their osteocyte perilacunar matrix during lactation. These studies show that osteocytes remove mineralized matrix through molecular mechanisms similar to those utilized by osteoclasts.
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Affiliation(s)
- Hai Qing
- School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, 64108, USA
| | - Laleh Ardeshirpour
- Section of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Paola Divieti Pajevic
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School Boston, MA 02114, USA
| | - Vladimir Dusevich
- School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, 64108, USA
| | - Katharina Jähn
- School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, 64108, USA
| | - Shigeaki Kato
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo, Japan
| | - John Wysolmerski
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Lynda F. Bonewald
- School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, 64108, USA
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Kirby BJ, Ardeshirpour L, Woodrow JP, Wysolmerski JJ, Sims NA, Karaplis AC, Kovacs CS. Skeletal recovery after weaning does not require PTHrP. J Bone Miner Res 2011; 26:1242-51. [PMID: 21308774 PMCID: PMC3179289 DOI: 10.1002/jbmr.339] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 11/28/2010] [Accepted: 01/13/2011] [Indexed: 12/12/2022]
Abstract
Mice lose 20% to 25% of trabecular bone mineral content (BMC) during lactation and restore it after weaning through unknown mechanisms. We found that tibial Pthrp mRNA expression was upregulated fivefold by 7 days after weaning versus end of lactation in wild-type (WT) mice. To determine whether parathyroid hormone-related protein (PTHrP) stimulates bone formation after weaning, we studied a conditional knockout in which PTHrP is deleted from preosteoblasts and osteoblasts by collagen I promoter-driven Cre (Cre(ColI) ). These mice are osteopenic as adults but have normal serum calcium, calcitriol, and parathyroid hormone (PTH). Pairs of Pthrp(flox/flox) ;Cre(ColI) (null) and WT;Cre(ColI) (WT) females were mated and studied through pregnancy, lactation, and 3 weeks of postweaning recovery. By end of lactation, both genotypes lost lumbar spine BMC: WT declined by 20.6% ± 3.3%, and null decreased by 22.5% ± 3.5% (p < .0001 versus baseline; p = NS between genotypes). During postweaning recovery, both restored BMC to baseline: WT to -3.6% ± 3.7% and null to 0.3% ± 3.7% (p = NS versus baseline or between genotypes). Similar loss and full recovery of BMC were seen at the whole body and hind limb. Histomorphometry confirmed that nulls had lower bone mass at baseline and that this was equal to the value achieved after weaning. Osteocalcin, propeptide of type 1 collagen (P1NP), and deoxypyridinoline increased equally during recovery in WT and null mice; PTH decreased and calcitriol increased equally; serum calcium was unchanged. Urine calcium increased during recovery but remained no different between genotypes. Although osteoblast-derived PTHrP is required to maintain adult bone mass and Pthrp mRNA upregulates in bone after weaning, it is not required for recovery of bone mass after lactation. The factors that stimulate postweaning bone formation remain unknown.
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Affiliation(s)
- Beth J Kirby
- Faculty of Medicine, Memorial University of NewfoundlandSt. John's, Newfoundland, Canada
| | - Laleh Ardeshirpour
- Faculty of Medicine, Yale University School of MedicineNew Haven, CT, USA
| | - Janine P Woodrow
- Faculty of Medicine, Memorial University of NewfoundlandSt. John's, Newfoundland, Canada
| | - John J Wysolmerski
- Faculty of Medicine, Yale University School of MedicineNew Haven, CT, USA
| | - Natalie A Sims
- St Vincent's Institute for Medical Research and Department of Medicine, St. Vincent's Hospital Melbourne, The University of MelbourneFitzroy, Victoria, Australia
| | - Andrew C Karaplis
- McGill University and Jewish General HospitalMontréal, Quebec, Canada
| | - Christopher S Kovacs
- Faculty of Medicine, Memorial University of NewfoundlandSt. John's, Newfoundland, Canada
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