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Cohen A. Bone Metabolism, Bone Mass, and Bone Structure During Pregnancy and Lactation: Normal Physiology and Pregnancy and Lactation-Associated Osteoporosis. Endocrinol Metab Clin North Am 2024; 53:453-470. [PMID: 39084819 DOI: 10.1016/j.ecl.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
This article reviews bone metabolism, bone mass, and bone structure changes expected during and after pregnancy and lactation, as well as the condition of pregnancy and lactation-associated osteoporosis (PLO)-a presentation with fragility fracture(s) in the context of these physiologic changes. Clinical implications of physiologic bone changes will be addressed, as will specific management considerations that apply to premenopausal women with PLO.
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Affiliation(s)
- Adi Cohen
- Division of Endocrinology, Department of Medicine, Columbia University, College of Physicians & Surgeons, 180 Fort Washington Avenue, HP9-910, New York, NY 10032, USA.
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2
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Sieverts M, Yee C, Nemani M, Parkinson DY, Alliston T, Acevedo C. Spatial control of perilacunar canalicular remodeling during lactation. Sci Rep 2024; 14:14655. [PMID: 38918485 PMCID: PMC11199490 DOI: 10.1038/s41598-024-63645-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 05/30/2024] [Indexed: 06/27/2024] Open
Abstract
Osteocytes locally remodel their surrounding tissue through perilacunar canalicular remodeling (PLR). During lactation, osteocytes remove minerals to satisfy the metabolic demand, resulting in increased lacunar volume, quantifiable with synchrotron X-ray radiation micro-tomography (SRµCT). Although the effects of lactation on PLR are well-studied, it remains unclear whether PLR occurs uniformly throughout the bone and what mechanisms prevent PLR from undermining bone quality. We used SRµCT imaging to conduct an in-depth spatial analysis of the impact of lactation and osteocyte-intrinsic MMP13 deletion on PLR in murine bone. We found larger lacunae undergoing PLR are located near canals in the mid-cortex or endosteum. We show lactation-induced hypomineralization occurs 14 µm away from lacunar edges, past a hypermineralized barrier. Our findings reveal that osteocyte-intrinsic MMP13 is crucial for lactation-induced PLR near lacunae in the mid-cortex but not for whole-bone resorption. This research highlights the spatial control of PLR on mineral distribution during lactation.
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Affiliation(s)
- Michael Sieverts
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, 84112, USA
| | - Cristal Yee
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | - Minali Nemani
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | | | - Tamara Alliston
- Department of Orthopedic Surgery, University of California, San Francisco, CA, 94131, USA
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, 84112, USA.
- Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, 92161, USA.
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3
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Lu AX, Lin Y, Li J, Liu JX, Yan CH, Zhang L. Effects of food-borne docosahexaenoic acid supplementation on bone lead mobilisation, mitochondrial function and serum metabolomics in pre-pregnancy lead-exposed lactating rats. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 337:122613. [PMID: 37757928 DOI: 10.1016/j.envpol.2023.122613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/01/2023] [Accepted: 09/22/2023] [Indexed: 09/29/2023]
Abstract
Large bone lead (Pb) resulting from high environmental exposure during childhood is an important source of endogenous Pb during pregnancy and lactation. Docosahexaenoic acid (DHA) attenuates Pb toxicity, however, the effect of DHA on bone Pb mobilisation during lactation has not been investigated. We aimed to study the effects of DHA supplementation during pregnancy and lactation on bone Pb mobilisation during lactation and its potential mechanisms. Weaning female rats were randomly divided into control (0.05% sodium acetate) and Pb-exposed (0.05% Pb acetate) groups, after a 4-week exposure by ad libitum drinking and a subsequent 4-week washout period, all female rats were mated with healthy males until pregnancy. Then exposed rats were randomly divided into Pb and Pb + DHA groups, and the latter was given a 0.14% DHA diet, while the remaining groups were given normal feed until the end of lactation. Pb and calcium levels, bone microarchitecture, bone turnover markers, mitochondrial function and serum metabolomics were analyzed. The results showed that higher blood and bone Pb levels were observed in the Pb group compared to the control, and there was a significant negative correlation between blood and bone Pb. Also, Pb increased trabecular bone loss along with slightly elevated serum C-telopeptide of type I collagen (CTX-I) levels. However, DHA reduced CTX-I levels and improved trabecular bone microarchitecture. Metabolomics showed that Pb affected mitochondrial function, which was further demonstrated in bone tissue by significant reductions in ATP levels, Na+-K+-ATPase, Ca2+-Mg2+-ATPase and CAT activities, and elevated levels of MDA, IL-1β and IL-18. However, these alterations were partially mitigated by DHA. In conclusion, DHA supplementation during pregnancy and lactation improved bone Pb mobilisation and mitochondrial dysfunction in lactating rats induced by pre-pregnancy Pb exposure, providing potential means of mitigating bone Pb mobilisation levels during lactation, but the mechanism still needs further study.
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Affiliation(s)
- An-Xin Lu
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Yin Lin
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Jing Li
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jun-Xia Liu
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Chong-Huai Yan
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China; Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Lin Zhang
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
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4
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Wang H, Liu Q, Jiang M, Song C, Liu D. Optimization of the dosage regimen of zoledronic acid with a kinetic-pharmacodynamic model and exposure-response analysis. Front Pharmacol 2023; 14:1089774. [PMID: 37829305 PMCID: PMC10565503 DOI: 10.3389/fphar.2023.1089774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 09/04/2023] [Indexed: 10/14/2023] Open
Abstract
Purpose: In order to support the dose optimization of zoledronic acid, the kinetic-pharmacodynamic model and exposure-response analysis were used to describe the changes in bone mineral density in different doses of zoledronic acid and establish the relationship between dose and acute phase reaction. Methods: Data were extracted from literature in accessible public databases. The kinetic-pharmacodynamic model was developed based on the above data using the NONMEM package to estimate parameters describing the relationship between the dose of zoledronic acid and bone mineral density. Exposure-response analysis was developed to establish the relationship between dose and acute phase reaction. Model evaluation was performed using goodness-of-fit, coefficient of variation (CV%). And sensitivity analyses were performed to assess the necessity of related parameters. Then the established model was used to simulate the changes of bone mineral density under different administration regimens, and the literature data was verified. Results: The kinetic-pharmacodynamic model successfully described zoledronic acid dose and change of bone mineral density in osteoporosis patients, with coefficient of variation of most less than 71.5%. The exposure-response analysis showed the incidence of acute phase reaction is dose-dependent. The bone mineral density was simulated based on the developed kinetic-pharmacodynamic model. And the simulated change of bone mineral density and the incidence of acute phase reaction could be helpful to propose a dosage regimen. Conclusion: Overall, the kinetic-pharmacodynamic model described changes of bone mineral density in different doses of zoledronic acid in vivo. And, the model and the exposure-response analysis also showed to provide the assessment of dose-response relationship for zoledronic acid.
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Affiliation(s)
- Huan Wang
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, China
- Center of Clinical Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital Beijing, Beijing, China
| | - Qi Liu
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, China
- Center of Clinical Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital Beijing, Beijing, China
| | - Muhan Jiang
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, China
- Center of Clinical Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital Beijing, Beijing, China
| | - Chunli Song
- Department of Orthopedics, Peking University Third Hospital, Beijing, China
- Center of Clinical Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital Beijing, Beijing, China
| | - Dongyang Liu
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, China
- Center of Clinical Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital Beijing, Beijing, China
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5
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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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6
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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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7
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Peculiarities of Integrating Mechanical Valves in Microfluidic Channels Using Direct Laser Writing. Appl Bionics Biomech 2022; 2022:9411024. [PMID: 36245929 PMCID: PMC9568359 DOI: 10.1155/2022/9411024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/20/2022] [Indexed: 12/03/2022] Open
Abstract
Regenerative medicine is a fast expanding scientific topic. One of the main areas of development directions in this field is the usage of additive manufacturing to fabricate functional components that would be later integrated directly into the human body. One such structure could be a microfluidic valve which could replace its biological counterpart in veins as it is worn out over the lifetime of a patient. In this work, we explore the possibility to produce such a structure by using multiphoton polymerization (MPP). This technology allows the creation of 3D structures on a micro- and nanometric scale. In this work, the fabrication of microfluidic systems by direct laser writing was carried out. These devices consist of a 100 μm diameter channel and within it a 200 μm long three-dimensional one-way mechanical valve. The idea of this device is to have a single flow direction for a fluid. For testing purposes, the valve was integrated into a femtosecond laser-made glass microfluidic system. Such a system acts as a platform for testing such small and delicate devices. Measurements of the dimensions of the device within such a testing platform were taken and the repeatability of this process was analyzed. The capability to use it for flow direction control is measured. Possible implications to the field of regenerative medicine are discussed.
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8
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Junno JA, Keisu A, Niinimäki M, Niinimäki J, Lehenkari P, Oura P. Gravidity, parity and knee breadth at midlife: a population-based cohort study. Sci Rep 2022; 12:12415. [PMID: 35858984 PMCID: PMC9300631 DOI: 10.1038/s41598-022-16231-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/06/2022] [Indexed: 11/16/2022] Open
Abstract
Gestation increases the biomechanical loading of lower extremities. Gestational loading may influence anthropometrics of articular surfaces in similar means as bone diaphyseal properties. This study aimed to investigate whether gravidity (i.e. number of pregnancies) and parity (i.e. number of deliveries) is associated with knee breadth among middle-aged women. The study sample comprised 815 women from the Northern Finland Birth Cohort 1966. The median parity count of our sample was 2 and the median gravidity count 3. At the age of 46, questionnaires were used to enquire gravidity and parity, and posteroanterior knee radiographs were used to obtain two knee breadth parameters (tibial plateau mediolateral breadth (TPML) and femoral condylar mediolateral breadth (FCML)) as representatives of articular size. The associations of gravidity and parity with knee breadth were analyzed using general linear models with adjustments for height, weight, leisure-time physical activity, smoking, and education years. Individuals with osteoarthritic changes were excluded from our sample. The mean TPML in our sample was 70.3 mm and the mean FCML 71.6 mm respectively. In the fully adjusted models, gravidity and parity showed positive associations with knee breadth. Each pregnancy was associated with 0.11–0.14% larger knee breath (p < 0.05), and each delivery accounted for an increase of 0.20% in knee breadth (p < 0.01). Between-group comparisons showed that multiparous women had 0.68–1.01% larger knee breath than nulli- and primiparous women (p < 0.05). Pregnancies and deliveries seem to increase the mediolateral breadth of the knee. This increase is potentially associated with increased biomechanical loadings during gestation.
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Affiliation(s)
- Juho-Antti Junno
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland. .,Anatomy and Cell Biology, Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, P.O. Box 5000, 90014, Oulu, Finland. .,Department of Archaeology, Faculty of Humanities, University of Oulu, Oulu, Finland. .,Archaeology, Faculty of Arts, University of Helsinki, Helsinki, Finland.
| | - Asla Keisu
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Anatomy and Cell Biology, Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, P.O. Box 5000, 90014, Oulu, Finland
| | - Maarit Niinimäki
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Department of Obstetrics and Gynecology, PEDEGO Research Unit, Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Jaakko Niinimäki
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
| | - Petri Lehenkari
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Anatomy and Cell Biology, Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, P.O. Box 5000, 90014, Oulu, Finland
| | - Petteri Oura
- Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland.,Center for Life Course Health Research, Faculty of Medicine, University of Oulu, Oulu, Finland.,Department of Forensic Medicine, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Forensic Medicine Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
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9
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Lai X, Chung R, Li Y, Liu XS, Wang L. Lactation alters fluid flow and solute transport in maternal skeleton: A multiscale modeling study on the effects of microstructural changes and loading frequency. Bone 2021; 151:116033. [PMID: 34102350 PMCID: PMC8276854 DOI: 10.1016/j.bone.2021.116033] [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: 04/23/2021] [Accepted: 06/01/2021] [Indexed: 01/02/2023]
Abstract
The female skeleton undergoes significant material and ultrastructural changes to meet high calcium demands during reproduction and lactation. Through the peri-lacunar/canalicular remodeling (PLR), osteocytes actively resorb surrounding matrix and enlarge their lacunae and canaliculi during lactation, which are quickly reversed after weaning. How these changes alter the physicochemical environment of osteocytes, the most abundant and primary mechanosensing cells in bone, are not well understood. In this study, we developed a multiscale poroelastic modeling technique to investigate lactation-induced changes in stress, fluid pressurization, fluid flow, and solute transport across multiple length scales (whole bone, porous midshaft cortex, lacunar-canalicular pore system (LCS), and pericellular matrix (PCM) around osteocytes) in murine tibiae subjected to axial compression at 3 N peak load (~320 με) at 0.5, 2, or 4 Hz. Based on previously reported skeletal anatomical measurements from lactating and nulliparous mice, our models demonstrated that loading frequency, LCS porosity, and PCM density were major determinants of fluid and solute flows responsible for osteocyte mechanosensing, cell-cell signaling, and metabolism. When loaded at 0.5 Hz, lactation-induced LCS expansion and potential PCM reduction promoted solute transport and osteocyte mechanosensing via primary cilia, but suppressed mechanosensing via fluid shear and/or drag force on the cell membrane. Interestingly, loading at 2 or 4 Hz was found to overcome the mechanosensing deficits observed at 0.5 Hz and these counter effects became more pronounced at 4 Hz and with sparser PCM in the lactating bone. Synergistically, higher loading frequency (2, 4 Hz) and sparser PCM enhanced flow-mediated mechanosensing and diffusion/convection of nutrients and signaling molecules for osteocytes. In summary, lactation-induced structural changes alter the local environment of osteocytes in ways that favor metabolism, mechanosensing, and post-weaning recovery of maternal bone. Thus, osteocytes play a role in balancing the metabolic and mechanical functions of female skeleton during reproduction and lactation.
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Affiliation(s)
- Xiaohan Lai
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China.
| | - Rebecca Chung
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Xiaowei Sherry Liu
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, United States.
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10
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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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11
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Rogowska MD, Pena UNV, Binning N, Christians JK. Recovery of the maternal skeleton after lactation is impaired by advanced maternal age but not by reduced IGF availability in the mouse. PLoS One 2021; 16:e0256906. [PMID: 34469481 PMCID: PMC8409645 DOI: 10.1371/journal.pone.0256906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/17/2021] [Indexed: 01/23/2023] Open
Abstract
Background Lactation results in substantial maternal bone loss that is recovered following weaning. However, the mechanisms underlying this recovery, and in particular the role of insulin-like growth factor 1 (IGF-I), is not clear. Furthermore, there is little data regarding whether recovery is affected by advanced maternal age. Methods Using micro-computed tomography, we studied bone recovery following lactation in mice at 2, 5 and 7 months of age. We also investigated the effects of reduced IGF-I availability using mice lacking PAPP-A2, a protease of insulin-like growth factor binding protein 5 (IGFBP-5). Results In 2 month old mice, lactation affected femoral trabecular and cortical bone, but only cortical bone showed recovery 3 weeks after weaning. This recovery was not affected by deletion of the Pappa2 gene. The amount of trabecular bone was reduced in 5 and 7 month old mice, and was not further reduced by lactation. However, the recovery of cortical bone was impaired at 5 and 7 months compared with at 2 months. Conclusions Recovery of the maternal skeleton after lactation is impaired in moderately-aged mice compared with younger mice. Our results may be relevant to the long-term effects of breastfeeding on the maternal skeleton in humans, particularly given the increasing median maternal age at childbearing.
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Affiliation(s)
- Monika D Rogowska
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Uriel N V Pena
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Nimrat Binning
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julian K Christians
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.,Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada.,British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada.,BC Women's Hospital and Health Centre, Women's Health Research Institute, Vancouver, British Columbia, Canada
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12
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Montoya‐Sanhueza G, Bennett NC, Oosthuizen MK, Dengler‐Crish CM, Chinsamy A. Bone remodeling in the longest living rodent, the naked mole-rat: Interelement variation and the effects of reproduction. J Anat 2021; 239:81-100. [PMID: 33554344 PMCID: PMC8197955 DOI: 10.1111/joa.13404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/09/2021] [Accepted: 01/14/2021] [Indexed: 12/14/2022] Open
Abstract
The pattern of bone remodeling of one of the most peculiar mammals in the world, the naked mole-rat (NMR), was assessed. NMRs are known for their long lifespans among rodents and for having low metabolic rates. We assessed long-term in vivo bone labeling of subordinate individuals, as well as the patterns of bone resorption and bone remodeling in a large sample including reproductive and non-reproductive individuals (n = 70). Over 268 undecalcified thin cross-sections from the midshaft of humerus, ulna, femur and tibia were analyzed with confocal fluorescence and polarized light microscopy. Fluorochrome analysis revealed low osteogenesis, scarce bone resorption and infrequent formation of secondary osteons (Haversian systems) (i.e., slow bone turnover), thus most likely reflecting the low metabolic rates of this species. Secondary osteons occurred regardless of reproductive status. However, considerable differences in the degree of bone remodeling were found between breeders and non-breeders. Pre-reproductive stages (subordinates) exhibited quite stable skeletal homeostasis and bone structure, although the attainment of sexual maturity and beginning of reproductive cycles in female breeders triggered a series of anabolic and catabolic processes that up-regulate bone turnover, most likely associated with the increased metabolic rates of reproduction. Furthermore, bone remodeling was more frequently found in stylopodial elements compared to zeugopodial elements. Despite the limited bone remodeling observed in NMRs, the variation in the pattern of skeletal homeostasis (interelement variation) reported here represents an important aspect to understand the skeletal dynamics of a small mammal with low metabolic rates. Given the relevance of the remodeling process among mammals, this study also permitted the comparison of such process with the well-documented histomorphology of extinct therapsids (i.e., mammalian precursors), thus evidencing that bone remodeling and its endocortical compartmentalization represent ancestral features among the lineage that gave rise to mammals. It is concluded that other factors associated with development (and not uniquely related to biomechanical loading) can also have an important role in the development of bone remodeling.
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Affiliation(s)
- Germán Montoya‐Sanhueza
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
- Department of ZoologyFaculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Nigel C. Bennett
- Department of Zoology and EntomologyMammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
| | - Maria K. Oosthuizen
- Department of Zoology and EntomologyMammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
| | | | - Anusuya Chinsamy
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
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13
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Panahi N, Ostovar A, Fahimfar N, Gharibzadeh S, Shafiee G, Heshmat R, Raeisi A, Nabipour I, Larijani B, Ghasem-Zadeh A. Grand multiparity associations with low bone mineral density and degraded trabecular bone pattern. Bone Rep 2021; 14:101071. [PMID: 33997148 PMCID: PMC8102397 DOI: 10.1016/j.bonr.2021.101071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 01/23/2023] Open
Abstract
Introduction Pregnancy is associated with changes in bone remodeling and calcium metabolism, which may increase the risk of fragility fracture after menopause. We hypothesized that in postmenopausal women, with history of grand multiparity, the magnitude of trabecular bone deterioration is associated with number of deliveries. Methods 1217 women aged 69.2 ± 6.4 years, from the Bushehr Elderly Health (BEH) program were recruited. The areal bone mineral density (aBMD) of the lumbar spine and femoral neck and trabecular bone score (TBS) of 916 postmenopausal women, with grand multiparity defined as more than 4 deliveries, were compared with those of 301 postmenopausal women with 4 or fewer deliveries. The association of multiparity with aBMDs and TBS were evaluated after adjustment for possible confounders including age, years since menopause, body mass index, and other relevant parameters. Results The aBMD of femoral neck (0.583 ± 0.110 vs. 0.603 ± 0.113 g/cm2), lumbar spine (0.805 ± 0.144 vs. 0.829 ± 0.140 g/cm2) and TBS (1.234 ± 0.086 vs. 1.260 ± 0.089) were significantly lower in women with history of grand multiparity than others. In the multiple regression analysis, after adjusting for confounders, the negative association did persist for lumbar spine aBMD (beta = −0.02, p value = 0.01), and the TBS (beta = −0.01, p value = 0.03), not for femoral neck aBMD. Conclusion We infer that grand multiparity have deleterious effects on the aBMD and the trabecular pattern of the lumbar spine.
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Affiliation(s)
- Nekoo Panahi
- Osteoporosis Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.,Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Afshin Ostovar
- Osteoporosis Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Noushin Fahimfar
- Osteoporosis Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Safoora Gharibzadeh
- Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran
| | - Gita Shafiee
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ramin Heshmat
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Raeisi
- School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Iraj Nabipour
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran
| | - Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Ghasem-Zadeh
- Department of Medicine and Endocrinology, Austin Health, University of Melbourne, Melbourne, Australia
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14
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Yoo JE, Shin DW, Han K, Kim D, Yoon JW, Lee DY. Association of Female Reproductive Factors With Incidence of Fracture Among Postmenopausal Women in Korea. JAMA Netw Open 2021; 4:e2030405. [PMID: 33404618 PMCID: PMC7788464 DOI: 10.1001/jamanetworkopen.2020.30405] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
IMPORTANCE Although estrogen level is positively associated with bone mineral density, there are limited data on the risk of fractures after menopause. OBJECTIVE To investigate whether female reproductive factors are associated with fractures among postmenopausal women. DESIGN, SETTING, AND PARTICIPANTS This population-based retrospective cohort study used data from the Korean National Health Insurance Service database on 1 272 115 postmenopausal women without previous fracture who underwent both cardiovascular and breast and/or cervical cancer screening from January 1 to December 31, 2009. Outcome data were obtained through December 31, 2018. EXPOSURES Information was obtained about reproductive factors (age at menarche, age at menopause, parity, breastfeeding, and exogenous hormone use) by self-administered questionnaire. MAIN OUTCOMES AND MEASURES Incidence of any fractures and site-specific fractures (vertebral, hip, and others). RESULTS Among the 1 272 115 participants, mean (SD) age was 61.0 (8.1) years. Compared with earlier age at menarche (≤12 years), later age at menarche (≥17 years) was associated with a higher risk of any fracture (adjusted hazard ratio [aHR], 1.24; 95% CI, 1.17-1.31) and vertebral fracture (aHR, 1.42; 95% CI, 1.28-1.58). Compared with earlier age at menopause (<40 years), later age at menopause (≥55 years) was associated with a lower risk of any fracture (aHR, 0.89; 95% CI, 0.86-0.93), vertebral fracture (aHR, 0.77; 95% CI, 0.73-0.81), and hip fracture (aHR, 0.88; 95% CI, 0.78-1.00). Longer reproductive span (≥40 years) was associated with lower risk of fractures compared with shorter reproductive span (<30 years) (any fracture: aHR, 0.86; 95% CI, 0.84-0.88; vertebral fracture: aHR, 0.73; 95% CI, 0.71-0.76; and hip fracture: aHR, 0.87; 95% CI, 0.80-0.95). Parous women had a lower risk of any fracture than nulliparous women (aHR, 0.96; 95% CI, 0.92-0.99). Although breastfeeding for 12 months or longer was associated with a higher risk of any fractures (aHR, 1.05; 95% CI, 1.03-1.08) and vertebral fractures (aHR, 1.22; 95% CI, 1.17-1.27), it was associated with a lower risk of hip fracture (aHR, 0.84; 95% CI, 0.76-0.93). Hormone therapy for 5 years or longer was associated with lower risk of any factures (aHR, 0.85; 95% CI, 0.83-0.88), while use of oral contraceptives for 1 year or longer was associated with a higher risk of any fractures (aHR, 1.03; 95% CI, 1.01-1.05). CONCLUSIONS AND RELEVANCE The findings of this cohort study suggest that female reproductive factors are independent risk factors for fracture, with a higher risk associated with shorter lifetime endogenous estrogen exposure. Interventions to reduce fracture risk may be needed for women at high risk, including those without osteoporosis.
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Affiliation(s)
- Jung Eun Yoo
- Healthcare System Gangnam Center, Department of Family Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Dong Wook Shin
- Department of Family Medicine and Supportive Care Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Science & Technology (SAIHST), Sungkyunkwan University, Seoul, Republic of Korea
| | - Kyungdo Han
- Department of Statistics and Actuarial Science, Soongsil University, Seoul, Republic of Korea
| | - Dahye Kim
- Department of Medical Statistics, The Catholic University of Korea, Seoul, Republic of Korea
| | - Ji Won Yoon
- Healthcare System Gangnam Center, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Dong-Yun Lee
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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15
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Kanakis I, Alameddine M, Scalabrin M, van 't Hof RJ, Liloglou T, Ozanne SE, Goljanek-Whysall K, Vasilaki A. Low protein intake during reproduction compromises the recovery of lactation-induced bone loss in female mouse dams without affecting skeletal muscles. FASEB J 2020; 34:11844-11859. [PMID: 32652768 DOI: 10.1096/fj.202001131r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/10/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022]
Abstract
Lactation-induced bone loss occurs due to high calcium requirements for fetal growth but skeletal recovery is normally achieved promptly postweaning. Dietary protein is vital for fetus and mother but the effects of protein undernutrition on the maternal skeleton and skeletal muscles are largely unknown. We used mouse dams fed with normal (N, 20%) or low (L, 8%) protein diet during gestation and lactation and maintained on the same diets (NN, LL) or switched from low to normal (LN) during a 28 d skeletal restoration period post lactation. Skeletal muscle morphology and neuromuscular junction integrity was not different between any of the groups. However, dams fed the low protein diet showed extensive bone loss by the end of lactation, followed by full skeletal recovery in NN dams, partial recovery in LN and poor bone recovery in LL dams. Primary osteoblasts from low protein diet fed mice showed decreased in vitro bone formation and decreased osteogenic marker gene expression; promoter methylation analysis by pyrosequencing showed no differences in Bmpr1a, Ptch1, Sirt1, Osx, and Igf1r osteoregulators, while miR-26a, -34a, and -125b expression was found altered in low protein fed mice. Therefore, normal protein diet is indispensable for maternal musculoskeletal health during the reproductive period.
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Affiliation(s)
- Ioannis Kanakis
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Moussira Alameddine
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Mattia Scalabrin
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Rob J van 't Hof
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Triantafillos Liloglou
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, UK
| | - Susan E Ozanne
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
| | - Katarzyna Goljanek-Whysall
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK.,Department of Physiology, School of Medicine, NUI Galway, Galway, Ireland
| | - Aphrodite Vasilaki
- Institute of Life Course and Medical Sciences, The MRC - Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
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16
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Ingle DN, Porter ME. Developmental changes in bone mechanics from Florida manatees ( Trichechus manatus latirostris), obligate swimming mammals. J Exp Biol 2020; 223:jeb213009. [PMID: 32098877 DOI: 10.1242/jeb.213009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 02/12/2020] [Indexed: 08/26/2023]
Abstract
Mammals living in aquatic environments load their axial skeletons differently from their terrestrial counterparts. The structure and mechanical behavior of trabecular bone can be especially indicative of varying habitual forces. Here, we investigated vertebral trabecular bone mechanical properties (yield strength, stiffness and toughness) throughout development in Florida manatees (Trichechus manatus latirostris), obligate undulatory swimmers. Thoracic, lumbar and caudal vertebrae were dissected from manatees (N=20) during necropsies. We extracted 6 mm3 samples from vertebral bodies and tested them in compression in three orientations (rostrocaudal, dorsoventral and mediolateral) at 2 mm min-1 We determined variation in mechanical properties between sexes, and among developmental stages, vertebral regions and testing orientations. We also investigated the relationships between vertebral process lengths and properties of dorsoventrally and mediolaterally tested bone. Rostrocaudally tested bone was the strongest, stiffest and toughest, suggesting that this is the principal direction of stress. Our results showed that bone from female subadults was stronger and stiffer than that of their male counterparts; based on these data, we hypothesize that hormonal shifts at sexual maturity may partially drive these differences. In calves, bone from the posterior region was stronger and tougher than that from the anterior region. We hypothesize that as animals grow rapidly throughout early development, bone in the posterior region would be the most ossified to support the rostrocaudal force propagation associated with undulatory swimming.
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Affiliation(s)
- Danielle N Ingle
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Marianne E Porter
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA
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17
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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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18
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Ross RD, Meagher MJ, Sumner DR. Calcium restriction during lactation has minimal effects on post-weaning mineral metabolism and bone recovery. J Bone Miner Metab 2019; 37:648-657. [PMID: 30361872 PMCID: PMC6548698 DOI: 10.1007/s00774-018-0969-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
Abstract
Dietary calcium (Ca) restriction during lactation in the rat, which induces intra-cortical and endocortical remodeling, has been proposed as a model to study bone matrix maturation in the adult skeleton. The purpose of this study was to assess the effects of dietary Ca restriction during lactation on post-weaning mineral metabolism and bone formation. Mated female Sprague-Dawley rats were randomized into groups receiving either 0.6% Ca (lactation/normal Ca) or 0.01% Ca (lactation/low Ca) diets during lactation. Virgin animals fed normal Ca were used as controls (virgin/normal Ca). At the time of weaning, animals on the low Ca diet were returned to normal Ca and cohorts of all three groups were sacrificed at days 0, 1, 2, 7, and 14 post-weaning. Lactation caused bone loss, particularly at the endocortical surface, but the amount was not affected by dietary Ca. Rats in the lactation/low Ca group had increased cortical porosity compared to the other groups, particularly within the size range of secondary osteons. Dietary Ca restriction during lactation did not affect post-weaning bone formation kinetics or serum Ca and phosphate levels. In both lactation groups, there was a transient increase in phosphate and fibroblast growth factor 23 (FGF23) post-weaning, which trended toward virgin/normal Ca levels over time. Thus, the additional challenge of low dietary Ca during lactation to induce intra-cortical remodeling in the rat has minimal effects on bone formation kinetics and mineral metabolism during the post-weaning period, providing further justification for this model to study matrix maturation in the adult skeleton.
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Affiliation(s)
- Ryan D Ross
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA
| | - Matthew J Meagher
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA
| | - D Rick Sumner
- Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, USA.
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA.
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19
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Cooke-Hubley S, Gao Z, Mugford G, Kaiser SM, Goltzman D, Leslie WD, Davison KS, Brown JP, Probyn L, Lentle B, Prior JC, Kovacs CS. Parity and lactation are not associated with incident fragility fractures or radiographic vertebral fractures over 16 years of follow-up: Canadian Multicentre Osteoporosis Study (CaMos). Arch Osteoporos 2019; 14:49. [PMID: 31037359 DOI: 10.1007/s11657-019-0601-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/21/2019] [Indexed: 02/03/2023]
Abstract
UNLABELLED Parity and lactation showed no associations with incident clinical fragility fractures or radiographic vertebral compression fractures in the 16-year CaMos prospective study. Parity was associated with slightly greater decline in femoral neck but not hip or spine areal bone mineral density (aBMD), while lactation showed no associations with aBMD change. PURPOSE Pregnancy and especially lactation cause loss of bone mass and microarchitectural changes, which temporarily increase fracture risk. After weaning, aBMD increases but skeletal microarchitecture may be incompletely restored. Most retrospective clinical studies found neutral or even protective associations of parity and lactation with fragility fractures, but prospective data are sparse. CaMos is a randomly selected observational cohort that includes ~ 6500 women followed prospectively for over 16 years. METHODS We determined whether parity or lactation were related to incident clinical fragility fractures over 16 years, radiographic (morphometric and morphologic) vertebral fractures over 10 years, and aBMD change (spine, total hip, and femoral neck) over 10 years. Parity and lactation duration were analyzed as continuous variables in predicting these outcomes using univariate and multivariate regression analyses. RESULTS Three thousand four hundred thirty-seven women completed 16 years of follow-up for incident clinical fractures, 3839 completed 10 years of morphometric vertebral fracture assessment, 3788 completed 10 years of morphologic vertebral fracture assessment, and 4464 completed 10 years of follow-up for change in aBMD. In the multivariate analyses, parity and lactation duration showed no associations with clinical fragility fractures, radiographic vertebral fractures, or change in aBMD, except that parity associated with a probable chance finding of a slightly greater decline in femoral neck aBMD. CONCLUSIONS Parity and lactation have no adverse associations with clinical fragility or radiographic vertebral fractures, or the rate of BMD decline over 10 years, in this prospective, multicenter study of a randomly selected, population-based cohort of women.
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Affiliation(s)
- Sandra Cooke-Hubley
- Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada
| | - Zhiwei Gao
- Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada
| | - Gerald Mugford
- Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada
| | - Stephanie M Kaiser
- Department of Medicine, Dalhousie University, Halifax, NS, B3H 2Y9, Canada
| | - David Goltzman
- Department of Medicine, McGill University, Montreal, QC, H4A 3J1, Canada
| | - William D Leslie
- Department of Medicine, University of Manitoba, Winnipeg, MB, R2H 2A6, Canada
| | - K Shawn Davison
- a priori medical sciences Inc., Victoria, BC, V8R 3E3, Canada
| | - Jacques P Brown
- Department of Medicine, Division of Rheumatology, CHU de Quebec Research Centre, Laval University, Quebec City, QC, G1V 4G2, Canada
| | - Linda Probyn
- Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, M4R 1K5, Canada
| | - Brian Lentle
- Department of Radiology, University of British Columbia, Vancouver, BC, V9A 6T5, Canada
| | - Jerilynn C Prior
- Centre for Menstrual Cycle and Ovulation Research, Medicine/Endocrinology, University of British Columbia, Vancouver, BC, V5Z 1M9, Canada
| | - Christopher S Kovacs
- Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada.
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20
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Effects of reproduction on sexual dimorphisms in rat bone mechanics. J Biomech 2018; 77:40-47. [PMID: 29961584 DOI: 10.1016/j.jbiomech.2018.06.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 06/07/2018] [Accepted: 06/19/2018] [Indexed: 12/27/2022]
Abstract
Osteoporosis most commonly affects postmenopausal women. Although men are also affected, women over 65 are 6 times more likely to develop osteoporosis than men of the same age. This is largely due to accelerated bone remodeling after menopause; however, the peak bone mass attained during young adulthood also plays an important role in osteoporosis risk. Multiple studies have demonstrated sexual dimorphisms in peak bone mass, and additionally, the female skeleton is significantly altered during pregnancy/lactation. Although clinical studies suggest that a reproductive history does not increase the risk of developing postmenopausal osteoporosis, reproduction has been shown to induce long-lasting alterations in maternal bone structure and mechanics, and the effects of pregnancy and lactation on maternal peak bone quality are not well understood. This study compared the structural and mechanical properties of male, virgin female, and post-reproductive female rat bone at multiple skeletal sites and at three different ages. We found that virgin females had a larger quantity of trabecular bone with greater trabecular number and more plate-like morphology, and, relative to their body weight, had a greater cortical bone size and greater bone strength than males. Post-reproductive females had altered trabecular microarchitecture relative to virgins, which was highly similar to that of male rats, and showed similar cortical bone size and bone mechanics to virgin females. This suggests that, to compensate for future reproductive bone losses, females may start off with more trabecular bone than is mechanically necessary, which may explain the paradox that reproduction induces long-lasting changes in maternal bone without increasing postmenopausal fracture risk.
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21
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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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22
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de Bakker CMJ, Tseng WJ, Li Y, Zhao H, Altman-Singles AR, Jeong Y, Robberts J, Han L, Kim DG, Sherry Liu X. Reproduction Differentially Affects Trabecular Bone Depending on Its Mechanical Versus Metabolic Role. J Biomech Eng 2018; 139:2657102. [PMID: 28979992 DOI: 10.1115/1.4038110] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 12/30/2022]
Abstract
During pregnancy and lactation, the maternal skeleton provides calcium for fetal/infant growth, resulting in substantial bone loss, which partially recovers after weaning. However, the amount of bone that is lost and the extent of post-weaning recovery are highly variable among different skeletal sites, and, despite persistent alterations in bone structure at some locations, reproductive history does not increase postmenopausal fracture risk. To explain this phenomenon, we hypothesized that the degree of reproductive bone loss/recovery at trabecular sites may vary depending on the extent to which the trabecular compartment is involved in the bone's load-bearing function. Using a rat model, we quantified the proportion of the load carried by the trabeculae, as well as the extent of reproductive bone loss and recovery, at two distinct skeletal sites: the tibia and lumbar vertebra. Both sites underwent significant bone loss during pregnancy and lactation, which was partially recovered post-weaning. However, the extent of the deterioration and the resumption of trabecular load-bearing capacity after weaning varied substantially. Tibial trabecular bone, which bore a low proportion of the total applied load, underwent dramatic and irreversible microstructural deterioration during reproduction. Meanwhile, vertebral trabecular bone bore a greater fraction of the load, underwent minimal deterioration in microarchitecture, and resumed its full load-bearing capacity after weaning. Because pregnancy and lactation are physiological processes, the distinctive responses to these natural events among different skeletal sites may help to elucidate the extent of the trabecular bone's structural versus metabolic functions.
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Affiliation(s)
- Chantal M J de Bakker
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 e-mail:
| | - Wei-Ju Tseng
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 e-mail:
| | - Yihan Li
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 e-mail:
| | - Hongbo Zhao
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.,Key Laboratory of Biorheological Science and Technology, Ministry of Education and Bioengineering College, Chongqing University, Chongqing 400044, China e-mail:
| | - Allison R Altman-Singles
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.,Department of Kinesiology, Pennsylvania State University, Berks Campus, Reading, PA 19610 e-mail:
| | - Yonghoon Jeong
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH 43210 e-mail:
| | - Juhanna Robberts
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 e-mail:
| | - Lin Han
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19104 e-mail:
| | - Do-Gyoon Kim
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH 43210 e-mail:
| | - X Sherry Liu
- McKay Orthopaedic Research Laboratory, Perelman School of Medicine, Department of Orthopaedic Surgery, University of Pennsylvania, 426C Stemmler Hall, 36th Street and Hamilton Walk Philadelphia, Philadelphia, PA 19104 e-mail:
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Suntornsaratoon P, Charoenphandhu N, Krishnamra N. Fortified tuna bone powder supplementation increases bone mineral density of lactating rats and their offspring. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2018; 98:2027-2034. [PMID: 28940514 DOI: 10.1002/jsfa.8688] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 09/07/2017] [Accepted: 09/13/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Breastfeeding leads to bone calcium loss for milk production, resulting in progressive maternal osteopenia. Calcium supplement from natural sources has been postulated to be more beneficial to bone health than purified CaCO3 because natural sources also contain other nutrients such as certain amino acids that might enhance calcium metabolism. Herein, we examined the effect of calcium supplementation from tuna bone powder and CaCO3 on bones of dams and the offspring. RESULTS Both forms of calcium supplement, i.e. tuna bone powder and CaCO3 , increased maternal bone mineral density (BMD). However, bone histomorphometry revealed that only tuna bone had beneficial effect on maternal bone microstructure, i.e. increased bone formation, decreased bone resorption and increased in bone volume. Regarding the mechanical properties, the decreased ultimate load in non-supplement lactating mothers was restored to the load seen in nulliparous animals by calcium supplementation. Moreover, both tuna bone and CaCO3 supplementation in mothers led to increased milk calcium concentration and consequently increased BMD in the growing offspring. CONCLUSION Calcium supplement from tuna bone powder was effective in preventing maternal osteopenia. Tuna bone, which is a readily available fishing industrial waste, is a good alternative source of calcium supplement that increases BMD in both lactating mothers and the neonates. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Panan Suntornsaratoon
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Narattaphol Charoenphandhu
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Nateetip Krishnamra
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Calcium and Bone Research, Faculty of Science, Mahidol University, Bangkok, Thailand
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Cooke-Hubley S, Kirby BJ, Valcour JE, Mugford G, Adachi JD, Kovacs CS. Spine bone mineral density increases after 6 months of exclusive lactation, even in women who keep breastfeeding. Arch Osteoporos 2017; 12:73. [PMID: 28815389 DOI: 10.1007/s11657-017-0368-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/07/2017] [Indexed: 02/03/2023]
Abstract
UNLABELLED This pilot study enrolled 31 women who had breastfed exclusively for 6 months. Lumbar and thoracic BMD increased 4 and 5%, respectively. Femoral neck and total body BMD did not change. Return of menses and progestin-only pill use were two potential signals that predicted a greater increase in BMD. PURPOSE/INTRODUCTION The skeleton is resorbed during lactation to provide much of the calcium content of milk. After lactation ceases, these deficits in skeletal mineral content are largely restored, such that lactation has a neutral or protective effect against the long-term risk of low bone mineral density (BMD), osteoporosis, and fragility fractures. We hypothesized that a large observational study may identify the factors that predict a greater increase in BMD after lactation ceases. A pilot study was first needed to test feasibility and the magnitude of expected BMD change. METHODS We undertook Factors Affecting Bone formation after Breastfeeding Pilot (FABB Pilot), which enrolled women who had breastfed exclusively for 6 months and planned to wean soon. The main outcome was change in BMD between enrolment and 6 months later. RESULTS Thirty-one women were recruited and completed both time points. Lumbar and thoracic spine BMD increased 4 and 5%, respectively; there was no significant change in femoral neck and total body BMD. Most women did not wean their babies as planned but continued to breastfeed multiple times per day. Despite this, a significant increase in BMD was seen in the subsequent 6 months. Return of spontaneous menses and use of a progestin-only pill at recruitment were two potential signals that predicted a greater increase in BMD during the 6 months after exclusive lactation. CONCLUSIONS Spine BMD increased significantly during 6 months following exclusive lactation and despite continued lactation. The factors that stimulate skeletal recovery remain to be identified.
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Affiliation(s)
- Sandra Cooke-Hubley
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Beth J Kirby
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - James E Valcour
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Gerald Mugford
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Jonathan D Adachi
- Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada
| | - Christopher S Kovacs
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada. .,Health Sciences Centre, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada.
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25
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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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26
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Kovacs CS. The Skeleton Is a Storehouse of Mineral That Is Plundered During Lactation and (Fully?) Replenished Afterwards. J Bone Miner Res 2017; 32:676-680. [PMID: 28177150 DOI: 10.1002/jbmr.3090] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 01/23/2017] [Accepted: 01/29/2017] [Indexed: 01/08/2023]
Abstract
During lactation, mammals resorb mineral from the maternal skeleton to provide calcium to milk. Rodents lose 25% to 35% of skeletal ash weight, ash calcium content, and bone mineral content as measured by dual-energy X-ray absorptiometry (DXA), and have compromised material properties of bone as assessed by crushing vertebrae and 3-point bend tests of femora or tibias. The strength, stiffness, and toughness of vertebrae, femora, and tibias are reduced by as much as 60%. The effects of lactation are not uniform throughout the skeleton, but instead resorption is much more marked in the trabecular-rich spine than in the appendicular skeleton or whole body. Women who breastfeed exclusively lose an average of 210 mg calcium in milk each day, whereas nursing of twins or triplets can double and triple the output of calcium. Clinical data are also consistent with skeletal calcium being released during lactation to provide much of the calcium needed for milk production. Lumbar spine bone mineral density (BMD), as assessed by DXA, declines by a mean of 5% to 10% among numerous studies during 3 to 6 months of exclusive lactation, whereas largely cortical sites (hip, forearm, whole body) show half that loss or no significant changes. Micro-CT of rodents and high-resolution peripheral quantitative computed tomography (HR-pQCT) imaging of women confirm that lactation causes microarchitectural deterioration of bone. These skeletal losses occur through two pathways: upregulated osteoclast-mediated bone resorption and osteocytic osteolysis, in which osteocytes remove mineral from their lacunae and pericanalicular spaces. After weaning, the skeleton is fully restored to its prior mineral content and strength in both animal models and humans, despite persistent microarchitectural changes observed in high-resolution imaging. Osteoblasts upregulate to lay down new osteoid, while osteocytes remineralize their surroundings. The factors that stimulate this post-weaning skeletal recovery remain unclear. In most studies, a history of lactation does not increase the risk, but may protect against, low BMD and fragility fractures. © 2017 American Society for Bone and Mineral Research.
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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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27
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Bjørnerem Å, Ghasem-Zadeh A, Wang X, Bui M, Walker SP, Zebaze R, Seeman E. Irreversible Deterioration of Cortical and Trabecular Microstructure Associated With Breastfeeding. J Bone Miner Res 2017; 32:681-687. [PMID: 27736021 DOI: 10.1002/jbmr.3018] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/04/2016] [Accepted: 10/11/2016] [Indexed: 01/07/2023]
Abstract
Estrogen deficiency associated with menopause is accompanied by an increase in the rate of bone remodeling and the appearance of a remodeling imbalance; each of the greater number of remodeling transactions deposits less bone than was resorbed, resulting in microstructural deterioration. The newly deposited bone is also less completely mineralized than the older bone resorbed. We examined whether breastfeeding, an estrogen-deficient state, compromises bone microstructure and matrix mineral density. Distal tibial and distal radial microarchitecture were quantified using high-resolution peripheral quantitative computed tomography in 58 women before, during, and after breastfeeding and in 48 controls during follow-up of 1 to 5 years. Five months of exclusive breastfeeding increased cortical porosity by 0.6% (95% confidence interval [CI] 0.3-0.9), reduced matrix mineralization density by 0.26% (95% CI 0.12-0.41) (both p < 0.01), reduced trabecular number by 0.22 per mm (95% CI 0.15-0.28), and increased trabecular separation by 0.07 mm (95% CI 0.05-0.08) (all p < 0.001). Relative to prebreastfeeding, at a median of 2.6 years (range 1 to 4.8) after cessation of breastfeeding, cortical porosity remained 0.58 SD (95% CI 0.48-0.68) higher, matrix mineralization density remained 1.28 SD (95% CI 1.07-1.49) lower, and trabeculae were 1.33 SD (95% CI 1.15-1.50) fewer and 1.06 SD (95% CI 0.91-1.22) more greatly separated (all p < 0.001). All deficits were greater than in controls. The results were similar at distal radius. Bone microstructure may be irreversibly deteriorated after cessation of breastfeeding at appendicular sites. Studies are needed to establish whether this deterioration compromises bone strength and increases fracture risk later in life. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Åshild Bjørnerem
- Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Department of Obstetrics and Gynecology, University Hospital of North Norway, Tromsø, Norway
| | - Ali Ghasem-Zadeh
- Endocrine Centre and Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia
| | - Xiaofang Wang
- Endocrine Centre and Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia
| | - Minh Bui
- Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Melbourne, Australia
| | - Susan P Walker
- Mercy Hospital for Women, Department of Obstetrics and Gynecology, University of Melbourne, Melbourne, Australia
| | - Roger Zebaze
- Endocrine Centre and Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia
| | - Ego Seeman
- Endocrine Centre and Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia.,Institute of Health and Ageing, Australian Catholic University, Melbourne, Australia
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28
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Kaya S, Basta-Pljakic J, Seref-Ferlengez Z, Majeska RJ, Cardoso L, Bromage T, Zhang Q, Flach CR, Mendelsohn R, Yakar S, Fritton SP, Schaffler MB. Lactation-Induced Changes in the Volume of Osteocyte Lacunar-Canalicular Space Alter Mechanical Properties in Cortical Bone Tissue. J Bone Miner Res 2017; 32:688-697. [PMID: 27859586 PMCID: PMC5395324 DOI: 10.1002/jbmr.3044] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/27/2016] [Accepted: 11/15/2016] [Indexed: 01/23/2023]
Abstract
Osteocytes can remove and remodel small amounts of their surrounding bone matrix through osteocytic osteolysis, which results in increased volume occupied by lacunar and canalicular space (LCS). It is well established that cortical bone stiffness and strength are strongly and inversely correlated with vascular porosity, but whether changes in LCS volume caused by osteocytic osteolysis are large enough to affect bone mechanical properties is not known. In the current studies we tested the hypotheses that (1) lactation and postlactation recovery in mice alter the elastic modulus of bone tissue, and (2) such local changes in mechanical properties are related predominantly to alterations in lacunar and canalicular volume rather than bone matrix composition. Mechanical testing was performed using microindentation to measure modulus in regions containing solely osteocytes and no vascular porosity. Lactation caused a significant (∼13%) reduction in bone tissue-level elastic modulus (p < 0.001). After 1 week postweaning (recovery), bone modulus levels returned to control levels and did not change further after 4 weeks of recovery. LCS porosity tracked inversely with changes in cortical bone modulus. Lacunar and canalicular void space increased 7% and 15% with lactation, respectively (p < 0.05), then returned to control levels at 1 week after weaning. Neither bone mineralization (assessed by high-resolution backscattered scanning electron microscopy) nor mineral/matrix ratio or crystallinity (assessed by Raman microspectroscopy) changed with lactation. Thus, changes in bone mechanical properties induced by lactation and recovery appear to depend predominantly on changes in osteocyte LCS dimensions. Moreover, this study demonstrates that tissue-level cortical bone mechanical properties are rapidly and reversibly modulated by osteocytes in response to physiological challenge. These data point to a hitherto unappreciated role for osteocytes in modulating and maintaining local bone mechanical properties. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Serra Kaya
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Jelena Basta-Pljakic
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | | | - Robert J Majeska
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Luis Cardoso
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Timothy Bromage
- Department of Biomaterials, New York University College of Dentistry, New York, NY, USA
| | - Qihong Zhang
- Department of Chemistry, Rutgers University, Newark, NJ, USA
| | - Carol R Flach
- Department of Chemistry, Rutgers University, Newark, NJ, USA
| | | | - Shoshana Yakar
- Department of Basic Science, New York University College of Dentistry, New York, NY, USA
| | - Susannah P Fritton
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Mitchell B Schaffler
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
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29
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Incorporation of Flaxseed Flour as a Dietary Source for ALA Increases Bone Density and Strength in Post-Partum Female Rats. Lipids 2017; 52:327-333. [DOI: 10.1007/s11745-017-4245-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 03/15/2017] [Indexed: 12/12/2022]
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30
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Abstract
Most premenopausal women with low trauma fracture(s) or low bone mineral density have a secondary cause of osteoporosis or bone loss. Where possible, treatment of the underlying cause should be the focus of management. Premenopausal women with an ongoing cause of bone loss and those who have had, or continue to have, low trauma fractures may require pharmacologic intervention. Clinical trials provide evidence of benefits of bisphosphonates and teriparatide for bone mineral density in several types of premenopausal osteoporosis, but studies are small and do not provide evidence regarding fracture risk reduction.
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Affiliation(s)
- Adi Cohen
- Division of Endocrinology, Department of Medicine, Columbia University Medical Center, Columbia University, College of Physicians & Surgeons, PH8-864, 630 West 168th Street, New York, NY 10032, USA.
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31
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Low SA, Galliford CV, Jones-Hall YL, Roy J, Yang J, Low PS, Kopeček J. Healing efficacy of fracture-targeted GSK3β inhibitor-loaded micelles for improved fracture repair. Nanomedicine (Lond) 2017; 12:185-193. [PMID: 28093944 DOI: 10.2217/nnm-2016-0340] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Aim: To evaluate the fracture healing capabilities of a GSK3β inhibitor, 6-bromoindirubin-3′-oxime, coupled with an aspartic acid octapeptide in a micellar delivery system. Materials & methods: The efficacy of the intravenously administered micelles to accelerate healing of femoral fracture in mice was evaluated. Micro-computed tomography analysis was employed to obtain bone density, total volume, relative volume, trabecular thickness and trabecular spacing.Results: Both fracture bone mineral density and volume were significantly higher in the micelle treatment groups when compared with controls. The fracture-targeted micelle demonstrates fracture-specific bone anabolism and biocompatibility in off-target tissues. Conclusion: Accelerated fracture healing in mice was achieved by targeting the GSK3β inhibitor, 6-bromoindirubin-3′-oxime, to the fracture site.
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Affiliation(s)
- Stewart A Low
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
| | - Chris V Galliford
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Yava L Jones-Hall
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - Jyoti Roy
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Jiyuan Yang
- Department of Pharmaceutics & Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Philip S Low
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Jindřich Kopeček
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
- Department of Pharmaceutics & Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA
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32
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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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Wendelboe MH, Thomsen JS, Henriksen K, Vegger JB, Brüel A. Zoledronate prevents lactation induced bone loss and results in additional post-lactation bone mass in mice. Bone 2016; 87:27-36. [PMID: 27021151 DOI: 10.1016/j.bone.2016.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 11/15/2022]
Abstract
In rodents, lactation is associated with a considerable and very rapid bone loss, which almost completely recovers after weaning. The aim of the present study was to investigate whether the bisphosphonate Zoledronate (Zln) can inhibit lactation induced bone loss, and if Zln interferes with recovery of bone mass after lactation has ceased. Seventy-six 10-weeks-old NMRI mice were divided into the following groups: Baseline, Pregnant, Lactation, Lactation+Zln, Recovery, Recovery+Zln, and Virgin Control (age-matched). The lactation period was 12days, then the pups were removed, and thereafter recovery took place for 28days. Zln, 100μg/kg, was given s.c. on the day of delivery, and again 4 and 8days later. Mechanical testing, μCT, and dynamic histomorphometry were performed. At L4, lactation resulted in a substantial loss of bone strength (-55% vs. Pregnant, p<0.01), BV/TV (-40% vs. Pregnant, p<0.01), and trabecular thickness (Tb.Th) (-29% vs. Pregnant, p<0.001). Treatment with Zln completely prevented lactation induced loss of bone strength, BV/TV, and Tb.Th at L4. Full recovery of micro-architectural and mechanical properties was found 28days after weaning in vehicle-treated mice. Interestingly, the recovery group treated with Zln during the lactation period had higher BV/TV (+45%, p<0.01) and Tb.Th (+16%, p<0.05) compared with virgin controls. Similar results were found at the proximal tibia and femur. This indicates that Zln did not interfere with the bone formation taking place after weaning. On this background, we conclude that post-lactation bone formation is not dependent on a preceding lactation induced bone loss.
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Affiliation(s)
- Mette Høegh Wendelboe
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, DK-8000 Aarhus C, Denmark.
| | - Jesper Skovhus Thomsen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, DK-8000 Aarhus C, Denmark.
| | - Kim Henriksen
- Nordic Bioscience A/S, Herlev Hovedgade 207, DK-2730 Herlev, Denmark.
| | - Jens Bay Vegger
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, DK-8000 Aarhus C, Denmark.
| | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, DK-8000 Aarhus C, Denmark.
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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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Romano T, Wark JD, Wlodek ME. Physiological skeletal gains and losses in rat mothers during pregnancy and lactation are not observed following uteroplacental insufficiency. Reprod Fertil Dev 2015; 26:385-94. [PMID: 23477709 DOI: 10.1071/rd12378] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 02/10/2013] [Indexed: 11/23/2022] Open
Abstract
Fluctuations in maternal bone mass during pregnancy and lactation facilitate calcium transfer to offspring. Uteroplacental insufficiency causes fetal growth restriction and programs poor adult bone health. We aimed to characterise maternal skeletal phenotype during normal pregnancy and pregnancy complicated by uteroplacental insufficiency. Uteroplacental restriction (Restricted) or sham surgery (Control) was performed on gestational Day 18 (term=22 days) in pregnant Wistar-Kyoto rats. Maternal right femurs were collected on embryonic Day 20, postnatal Day 1 and Weeks 5, 7 and 9 postnatal. Dual-energy X-ray absorptiometry was used to quantify global bone mineral content, density and body composition. Peripheral quantitative computed tomography was utilised to determine trabecular and cortical content, density, circumferences and strength. Control rats exhibited expected reductions in trabecular and cortical content, density and bone strength from embryonic Day 20 to postnatal Day 1 (P<0.05). These skeletal alterations were absent in Restricted rats. By postnatal Day 7, bone parameters in Control and Restricted rats were not different from non-pregnant rats, indicating restoration of maternal bone. The lack of bone loss in mothers suffering uteroplacental insufficiency suggests that calcium transfer to pups would be impaired. This reduction in calcium availability is a likely contributor to the programming of poor adult bone health in growth-restricted offspring.
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Affiliation(s)
- Tania Romano
- Department of Physiology, The University of Melbourne, Vic. 3010, Australia
| | - John D Wark
- Department of Medicine, The University of Melbourne, Vic. 3010, Australia
| | - Mary E Wlodek
- Department of Physiology, The University of Melbourne, Vic. 3010, Australia
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Peric M, Dumic-Cule I, Grcevic D, Matijasic M, Verbanac D, Paul R, Grgurevic L, Trkulja V, Bagi CM, Vukicevic S. The rational use of animal models in the evaluation of novel bone regenerative therapies. Bone 2015; 70:73-86. [PMID: 25029375 DOI: 10.1016/j.bone.2014.07.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/30/2014] [Accepted: 07/05/2014] [Indexed: 12/31/2022]
Abstract
Bone has a high potential for endogenous self-repair. However, due to population aging, human diseases with impaired bone regeneration are on the rise. Current strategies to facilitate bone healing include various biomolecules, cellular therapies, biomaterials and different combinations of these. Animal models for testing novel regenerative therapies remain the gold standard in pre-clinical phases of drug discovery and development. Despite improvements in animal experimentation, excessive poorly designed animal studies with inappropriate endpoints and inaccurate conclusions are being conducted. In this review, we discuss animal models, procedures, methods and technologies used in bone repair studies with the aim to assist investigators in planning and performing scientifically sound experiments that respect the wellbeing of animals. In the process of designing an animal study for bone repair investigators should consider: skeletal characteristics of the selected animal species; a suitable animal model that mimics the intended clinical indication; an appropriate assessment plan with validated methods, markers, timing, endpoints and scoring systems; relevant dosing and statistically pre-justified sample sizes and evaluation methods; synchronization of the study with regulatory requirements and additional evaluations specific to cell-based approaches. This article is part of a Special Issue entitled "Stem Cells and Bone".
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Affiliation(s)
- Mihaela Peric
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Department for Intercellular Communication, Salata 2, Zagreb, Croatia.
| | - Ivo Dumic-Cule
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Laboratory for Mineralized Tissues, Salata 11, Zagreb, Croatia
| | - Danka Grcevic
- University of Zagreb School of Medicine, Department of Physiology and Immunology, Salata 3, Zagreb, Croatia
| | - Mario Matijasic
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Department for Intercellular Communication, Salata 2, Zagreb, Croatia
| | - Donatella Verbanac
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Department for Intercellular Communication, Salata 2, Zagreb, Croatia
| | - Ruth Paul
- Paul Regulatory Services Ltd, Fisher Hill Way, Cardiff CF15 8DR, UK
| | - Lovorka Grgurevic
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Laboratory for Mineralized Tissues, Salata 11, Zagreb, Croatia
| | - Vladimir Trkulja
- University of Zagreb School of Medicine, Department of Pharmacology, Salata 11, Zagreb, Croatia
| | - Cedo M Bagi
- Pfizer Inc., Global Research and Development, Global Science and Technology, 100 Eastern Point Road, Groton, CT 06340, USA
| | - Slobodan Vukicevic
- University of Zagreb School of Medicine, Center for Translational and Clinical Research, Laboratory for Mineralized Tissues, Salata 11, Zagreb, Croatia.
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Doherty AH, Ghalambor CK, Donahue SW. Evolutionary Physiology of Bone: Bone Metabolism in Changing Environments. Physiology (Bethesda) 2015; 30:17-29. [DOI: 10.1152/physiol.00022.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bone evolved to serve many mechanical and physiological functions. Osteocytes and bone remodeling first appeared in the dermal skeleton of fish, and subsequently adapted to various challenges in terrestrial animals occupying diverse environments. This review discusses the physiology of bone and its role in mechanical and calcium homeostases from an evolutionary perspective. We review how bone physiology responds to changing environments and the adaptations to unique and extreme physiological conditions.
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Affiliation(s)
- Alison H. Doherty
- Department of Mechanical Engineering, Flint Animal Cancer Center, Colorado State University, Fort Collins, Colorado; and
| | - Cameron K. Ghalambor
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado
| | - Seth W. Donahue
- Department of Mechanical Engineering, Flint Animal Cancer Center, Colorado State University, Fort Collins, Colorado; and
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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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Kovacs CS. The Role of PTHrP in Regulating Mineral Metabolism During Pregnancy, Lactation, and Fetal/Neonatal Development. Clin Rev Bone Miner Metab 2014. [DOI: 10.1007/s12018-014-9157-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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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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Keiler AM, Bernhardt R, Scharnweber D, Jarry H, Vollmer G, Zierau O. Comparison of estrogenic responses in bone and uterus depending on the parity status in Lewis rats. J Steroid Biochem Mol Biol 2013; 133:101-9. [PMID: 23032373 DOI: 10.1016/j.jsbmb.2012.09.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 09/04/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
The reproductive transition of women through peri- to postmenopause is characterized by changes in steroid hormone levels due to the cessation of the ovarian function. Beside several complaints associated with these hormonal changes, the deterioration of the trabecular bone micro-architecture and the loss of skeletal mass can cause osteoporosis. At this life stage, women often have a reproductive history of one to several pregnancies. The ovariectomized skeletally mature rat (>10 months old) is one of the most commonly used animal models for postmenopausal osteoporosis research. Despite the fact that mammals can undergo up to several reproductive cycles (primi-/pluriparous), nulliparous animals are often used and the question whether changes in the hormonal milieu subsequently affect the skeleton and influence the outcome of intervention studies is often neglected in study designs. Therefore, the aim of the present study was to compare the estrogen responsiveness of nulliparous and pluriparous rats. For this purpose, one year old virgin or retired breeder Lewis rats were either sham operated or ovariectomized, whereas half of the ovariectomized animals received subcutaneous 17β-estradiol pellets eight weeks after surgery. After another four weeks, the effects on the uterus were determined by expression analysis of estrogen-dependently regulated steroid receptor genes and well-established marker genes. Moreover, trabecular bone parameters in the tibia were analyzed by micro-computed tomography (μCT). Parity-dependency in estrogen responsiveness was observed with respect to the achieved serum E2 levels in response to similar E2 treatment. This led to differences both on the uterus wet weight and on the expression level of uterine target genes. In addition, a reversal of the ovariectomy-induced changes of the bone architecture after 17β-estradiol substitution was only observed among the nulliparous. In conclusion, the observations of this study support parity-dependent differences in the responses to estrogenic compounds in the uterus and the bone of rats. These results indicate that the parity-status has an impact on the outcome of studies aiming at the investigation of estrogenic effects of compounds potentially used in hormone replacement and thus, this should be taken into consideration for further studies and particularly for the discussion of data obtained with the preclinical ovariectomized rat animal model.
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Affiliation(s)
- Annekathrin Martina Keiler
- Institute of Zoology, Molecular Cell Physiology and Endocrinology, Technische Universität Dresden, 01062 Dresden, Germany.
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Mechanistic investigations on the etiology of Risperdal® Consta®-induced bone changes in female Wistar Hannover rats. Toxicology 2012; 299:90-8. [DOI: 10.1016/j.tox.2012.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/04/2012] [Accepted: 05/05/2012] [Indexed: 11/21/2022]
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Hood WR. A Test of Bone Mobilization Relative to Reproductive Demand: Skeletal Quality Is Improved in Cannibalistic Females with Large Litters. Physiol Biochem Zool 2012; 85:385-96. [DOI: 10.1086/666057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Liu XS, Ardeshirpour L, VanHouten JN, Shane E, Wysolmerski JJ. Site-specific changes in bone microarchitecture, mineralization, and stiffness during lactation and after weaning in mice. J Bone Miner Res 2012; 27:865-75. [PMID: 22189918 DOI: 10.1002/jbmr.1503] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Despite the dramatic bone loss that occurs during lactation, bone mineral density rapidly recovers after offspring are weaned and milk production stops. The goal of this study is to quantify site-specific changes in bone quantity and quality during and after lactation in a mouse model. We used micro computed tomography (µCT), individual trabecula segmentation (ITS), digital topological analysis (DTA)-based tissue mineral density (TMD) analysis, and micro finite element analysis (µFEA) to quantify the effects of lactation and weaning on bone microarchitecture, mineralization, and stiffness at the spine, tibia, and femur. We found a significant decrease in trabecular plate microarchitecture, tissue mineralization of the trabecular surface, trabecular central skeleton, and intervening envelopes, and whole bone stiffness in lactating versus nulliparous mice at all three sites. In recovered mice, all these different aspects of bone quality were comparable to nulliparous mice at the spine. In contrast, trabecular plate microarchitecture and whole bone stiffness at the tibia and femur in recovered mice were lower than nulliparous mice, as were central trabecular tissue mineralization and cortical structure at the femur. These findings are consistent with clinical observations of partial recovery of femoral bone mineral density BMD after lactation in humans. The observed differences in trabecular surface tissue mineralization in nulliparous, lactating, and recovered mice are consistent with prior observations that maternal bone turnover shifts from resorption to formation at the time of pup weaning. The significant differences in trabecular central tissue mineralization during these three states suggest that osteocytes may contribute to the reversible loss of mineral during and after lactation. Future studies are necessary to determine whether differing functions of various bone cells at individual skeletal sites cause site-specific skeletal changes during and after lactation.
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Affiliation(s)
- X Sherry Liu
- Division of Endocrinology, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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Rosa BV, Firth EC, Blair HT, Vickers MH, Morel PCH. Voluntary exercise in pregnant rats positively influences fetal growth without initiating a maternal physiological stress response. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1134-41. [DOI: 10.1152/ajpregu.00683.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effects of increased physical activity during pregnancy on the health of the offspring in later life are unknown. Research in this field requires an animal model of exercise during pregnancy that is sufficiently strenuous to cause an effect but does not elicit a stress response. Previously, we demonstrated that two models of voluntary exercise in the nonpregnant rat, tower climbing and rising to an erect bipedal stance (squat), cause bone modeling without elevating the stress hormone corticosterone. In this study, these same models were applied to pregnant rats. Gravid Wistar rats were randomly divided into three groups: control, tower climbing, and squat exercise. The rats exercised throughout pregnancy and were killed at day 19. Maternal stress was assessed by fecal corticosterone measurement. Maternal bone and soft tissue responses to exercise were assessed by peripheral quantitative computed tomography and dual-energy X-ray absorptiometry. Maternal weight gain during the first 19 days of pregnancy was less in exercised than in nonexercised pregnant control rats. Fecal corticosterone levels did not differ between the three maternal groups. The fetuses responded to maternal exercise in a uterine position-dependent manner. Mid-uterine horn fetuses from the squat exercise group were heavier ( P < 0.0001) and longer ( P < 0.0001) and had a greater placental weight ( P = 0.001) than those from control rats. Fetuses from tower-climbing dams were longer ( P < 0.0001) and had heavier placentas ( P = 0.01) than those from control rats, but fetal weight did not differ from controls. These models of voluntary exercise in the rat may be useful for future studies of the effects of exercise during pregnancy on the developmental origins of health and disease.
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Affiliation(s)
- Brielle V. Rosa
- National Research Centre for Growth and Development, Institute of Veterinary, Animal, and Biomedical Sciences,
| | - Elwyn C. Firth
- National Research Centre for Growth and Development, Institute of Veterinary, Animal, and Biomedical Sciences,
| | - Hugh T. Blair
- National Research Centre for Growth and Development, Institute of Veterinary, Animal, and Biomedical Sciences,
| | - Mark H. Vickers
- National Research Centre for Growth and Development, Liggins Institute, University of Auckland, Auckland, New Zealand
| | - Patrick C. H. Morel
- National Research Centre for Growth and Development, Institute of Food, Nutrition, and Human Health, Massey University, Palmerston North; and
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Abstract
The objective of this study was to examine the differences in sow metacarpal properties through various parities and to compare the incidence of locomotory problems between stalled and loose-housed sows. Metacarpals (n = 110) of sows from six farms were collected at slaughter and stored at -20°C. Bones from one forelimb of sows in stalls (n = 36) and loose-housed (n = 20) were collected and their articular surfaces examined for Osteochondrosis Dissecans (OCD), these sows were also scored for lameness pre-slaughter. Metacarpals were CT scanned for cross sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and calculating bone strength indices. The results show there was little change in bone mineral status throughout the range of parities examined and overall metacarpal integrity was not compromised by multiple production cycles. There were no differences detected in the incidence of lameness or joint pathology between housing systems.
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Affiliation(s)
- Wf Ryan
- Department of Pig Production Teagasc, Moorepark Research Centre, Fermoy, Co, Cork, Ireland
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Wysolmerski JJ. Interactions between breast, bone, and brain regulate mineral and skeletal metabolism during lactation. Ann N Y Acad Sci 2010; 1192:161-9. [PMID: 20392232 DOI: 10.1111/j.1749-6632.2009.05249.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mammalian reproduction requires that nursing mothers transfer large amounts of calcium to their offspring through milk. As a result, lactation is associated with dramatic alterations in bone and mineral metabolism, including reversible bone loss. One theme that has emerged from recent studies examining these adaptations is that the lactating breast actively participates in regulating bone and mineral metabolism. This review will detail our current knowledge of interactions between the breast, skeleton, and hypothalamus during lactation and will consider implications that this reproductive physiology has for the pathophysiology of osteoporosis and breast cancer.
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Dengler-Crish CM, Catania KC. Cessation of reproduction-related spine elongation after multiple breeding cycles in female naked mole-rats. Anat Rec (Hoboken) 2009; 292:131-7. [PMID: 18951517 DOI: 10.1002/ar.20793] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The breeding female or "queen" naked mole-rat has a uniquely elongated body morphology attributed to the lengthening of the lumbar vertebral column that occurs during pregnancy. It is unknown whether this vertebral growth is a continuous process, or associated only with early reproductive experience. We compared pregnancy-related bone elongation in nascent primiparous queens and established queens to determine if this vertebral expansion was a lifelong process in these females. We also investigated the impact of lactation on vertebral elongation in these mole-rats because it is known to be a time of significant bone loss in other mammals. Our data show that after eight or more pregnancies, established queens no longer experienced a net gain in lumbar spine length over the reproductive cycle, whereas the nascent breeders demonstrated significant spine lengthening over this time. Despite the lack of net spine lengthening in established breeders, our results indicated that these queens still experienced some pregnancy-specific vertebral elongation. In naked mole-rats, pregnancy-induced bone elongation may serve the dual purposes of first lengthening the spine, and then once optimal spine size is achieved, serving as a homeostatic mechanism that prepares the spine for the mineral demands of lactation. Anat Rec, 2009. (c) 2008 Wiley-Liss, Inc.
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Peterson CA, Schnell JD, Kubas KL, Rottinghaus GE. Effects of soy isoflavone consumption on bone structure and milk mineral concentration in a rat model of lactation-associated bone loss. Eur J Nutr 2009; 48:84-91. [PMID: 19093161 DOI: 10.1007/s00394-008-0765-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 11/28/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Like menopause, during complete lactation, circulating estrogen concentrations are markedly reduced, resulting in amplified bone resorption. AIM OF STUDY To investigate the effects of soy isoflavones, common dietary components used to mitigate the bone loss of menopause, on the bone loss associated with lactation. METHODS Lactating rats were randomized to one of four diets supplemented with different levels of soy isoflavones (0, 2, 4, 8 mg aglycone isoflavone/g protein). Milk was collected from all dams between days 12 and 15 of lactation and was analyzed for calcium, phosphorus and genistein concentrations. Serum and bones from half of the animals from each diet group were taken at weaning and from the remaining half at 4 weeks post-weaning. Bones underwent histomorphometric analysis and serum was used for genistein determinations. RESULTS Serum genistein and milk concentrations reflected dietary isoflavone dose. Isoflavone intake had no effect on any of the bone changes associated with lactation or recovery. Milk calcium and mineral concentrations were unaffected by dietary isoflavones. CONCLUSIONS Consumption of soy isoflavones, in levels that can be readily attained through soy foods, have neither protective effects on bone nor deleterious effects on milk quality or quantity during lactation.
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Affiliation(s)
- Catherine A Peterson
- Dept. of Nutritional Sciences, University of Missouri, 217 Gwynn Hall, Columbia, MO 65211, USA.
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