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Turner RT, Branscum AJ, Iwaniec UT. Long-duration leptin transgene expression in dorsal vagal complex does not alter bone parameters in female Sprague Dawley rats. Bone Rep 2024; 21:101769. [PMID: 38706522 PMCID: PMC11067478 DOI: 10.1016/j.bonr.2024.101769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/21/2024] [Accepted: 04/23/2024] [Indexed: 05/07/2024] Open
Abstract
The hypothalamus and dorsal vagal complex (DVC) are both important for integration of signals that regulate energy balance. Increased leptin transgene expression in either the hypothalamus or DVC of female rats was shown to decrease white adipose tissue and circulating levels of leptin and adiponectin. However, in contrast to hypothalamus, leptin transgene expression in the DVC had no effect on food intake, circulating insulin, ghrelin and glucose, nor on thermogenic energy expenditure. These findings imply different roles for hypothalamus and DVC in leptin signaling. Leptin signaling is required for normal bone accrual and turnover. Leptin transgene expression in the hypothalamus normalized the skeletal phenotype of leptin-deficient ob/ob mice but had no long-duration (≥10 weeks) effects on the skeleton of leptin-replete rats. The goal of this investigation was to determine the long-duration effects of leptin transgene expression in the DVC on the skeleton of leptin-replete rats. To accomplish this goal, we analyzed bone from three-month-old female rats that were microinjected with recombinant adeno-associated virus encoding either rat leptin (rAAV-Leptin, n = 6) or green fluorescent protein (rAAV-GFP, control, n = 5) gene. Representative bones from the appendicular (femur) and axial (3rd lumbar vertebra) skeleton were evaluated following 10 weeks of treatment. Selectively increasing leptin transgene expression in the DVC had no effect on femur cortical or cancellous bone microarchitecture. Additionally, increasing leptin transgene expression had no effect on vertebral osteoblast-lined or osteoclast-lined bone perimeter or marrow adiposity. Taken together, the findings suggest that activation of leptin receptors in the DVC has minimal specific effects on the skeleton of leptin-replete female rats.
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Affiliation(s)
- Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
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2
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Li X, Fu X, Li H, Gao Y, Wang W, Shen Y. Leptin differentially regulate cell apoptosis and cycle by histone acetylation in tibial and vertebral epiphyseal plates. Cell Biol Int 2023; 47:660-668. [PMID: 36453460 DOI: 10.1002/cbin.11968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/31/2022] [Accepted: 11/19/2022] [Indexed: 12/03/2022]
Abstract
Leptin showed different apoptosis regulation effects on the chondrocytes from tibial and vertebral epiphyseal plates. However, the mechanism is still unclear. In this study, we tested the protein profile of tibial and vertebral epiphyseal plate chondrocytes with and without leptin stimulation by mass spectrometry and found that the histone acetylation level of tibial chondrocytes was decreased after leptin treatment, while increased in vertebral epiphyseal plates. COIP assay showed that leptin promoted H3, H4 histone acetylation by recruiting CREB binding protein (CBP)/P300 to activate histone acetyl transferases (HATs) activity in vertebral disc chondrocytes. But in tibial plate cartilage cells, leptin did not recruit CBP and p300, thus differently affect the apoptosis of epiphyseal plate chondrocytes. Through explored the mechanism of histone acetylation modulated by leptin, and its effect on cartilage cell apoptosis and cell cycle regulation, This provides a novel target therapy possibility therapeutic approach to for the related disease.
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Affiliation(s)
- Xiaomiao Li
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Xiaodong Fu
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Hao Li
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yingjian Gao
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Weili Wang
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yi Shen
- Department of Orthopedics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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3
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Misch M, Puthanveetil P. The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems. Int J Mol Sci 2022; 23:ijms23105439. [PMID: 35628271 PMCID: PMC9141226 DOI: 10.3390/ijms23105439] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/30/2022] [Accepted: 05/10/2022] [Indexed: 12/12/2022] Open
Abstract
Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.
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Affiliation(s)
- Monica Misch
- Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, IL 60515, USA;
| | - Prasanth Puthanveetil
- Department of Pharmacology, College of Graduate Studies, Midwestern University, Downers Grove, IL 60515, USA
- Correspondence: ; Tel.: +1-630-960-3935
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Turner RT, Wong CP, Fosse KM, Branscum AJ, Iwaniec UT. Caloric Restriction and Hypothalamic Leptin Gene Therapy Have Differential Effects on Energy Partitioning in Adult Female Rats. Int J Mol Sci 2021; 22:ijms22136789. [PMID: 34202651 PMCID: PMC8269114 DOI: 10.3390/ijms22136789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/04/2021] [Accepted: 06/18/2021] [Indexed: 12/14/2022] Open
Abstract
Dieting is a common but often ineffective long-term strategy for preventing weight gain. Similar to humans, adult rats exhibit progressive weight gain. The adipokine leptin regulates appetite and energy expenditure but hyperleptinemia is associated with leptin resistance. Here, we compared the effects of increasing leptin levels in the hypothalamus using gene therapy with conventional caloric restriction on weight gain, food consumption, serum leptin and adiponectin levels, white adipose tissue, marrow adipose tissue, and bone in nine-month-old female Sprague-Dawley rats. Rats (n = 16) were implanted with a cannula in the 3rd ventricle of the hypothalamus and injected with a recombinant adeno-associated virus, encoding the rat gene for leptin (rAAV-Lep), and maintained on standard rat chow for 18 weeks. A second group (n = 15) was calorically-restricted to match the weight of the rAAV-Lep group. Both approaches prevented weight gain, and no differences in bone were detected. However, calorically-restricted rats consumed 15% less food and had lower brown adipose tissue Ucp-1 mRNA expression than rAAV-Lep rats. Additionally, calorically-restricted rats had higher abdominal white adipose tissue mass, higher serum leptin and adiponectin levels, and higher marrow adiposity. Caloric restriction and hypothalamic leptin gene therapy, while equally effective in preventing weight gain, differ in their effects on energy intake, energy expenditure, adipokine levels, and body composition.
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Affiliation(s)
- Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA; (R.T.T.); (C.P.W.); (K.M.F.)
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA; (R.T.T.); (C.P.W.); (K.M.F.)
| | - Kristina M. Fosse
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA; (R.T.T.); (C.P.W.); (K.M.F.)
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA;
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA; (R.T.T.); (C.P.W.); (K.M.F.)
- Correspondence:
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5
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Keune JA, Branscum AJ, Wong CP, Iwaniec UT, Turner RT. Effect of Leptin Deficiency on the Skeletal Response to Hindlimb Unloading in Adult Male Mice. Sci Rep 2019; 9:9336. [PMID: 31249331 PMCID: PMC6597714 DOI: 10.1038/s41598-019-45587-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/06/2019] [Indexed: 12/29/2022] Open
Abstract
Based on body weight, morbidly obese leptin-deficient ob/ob mice have less bone than expected, suggesting that leptin plays a role in the skeletal response to weight bearing. To evaluate this possibility, we compared the skeletal response of wild type (WT) and ob/ob mice to hindlimb unloading (HU). Mice were individually housed at 32 °C (thermoneutral) from 4 weeks of age (rapidly growing) to 16 weeks of age (approaching skeletal maturity). Mice were then randomized into one of 4 groups (n = 10/group): (1) WT control, (2) WT HU, (3) ob/ob control, and (4) ob/ob HU and the results analyzed by 2-way ANOVA. ob/ob mice pair-fed to WT mice had normal cancellous bone volume fraction (BV/TV) in distal femur, lower femur length and total bone area, mineral content (BMC) and density (BMD), and higher cancellous bone volume fraction in lumbar vertebra (LV). HU resulted in lower BMC and BMD in total femur, and lower BV/TV in distal femur and LV in both genotypes. Cancellous bone loss in femur in both genotypes was associated with increases in osteoclast-lined bone perimeter. In summary, leptin deficiency did not attenuate HU-induced osteopenia in male mice, suggesting that leptin is not required for bone loss induced by unweighting.
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Affiliation(s)
- Jessica A. Keune
- 0000 0001 2112 1969grid.4391.fSkeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331 USA
| | - Adam J. Branscum
- 0000 0001 2112 1969grid.4391.fBiostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331 USA
| | - Carmen P. Wong
- 0000 0001 2112 1969grid.4391.fSkeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331 USA
| | - Urszula T. Iwaniec
- 0000 0001 2112 1969grid.4391.fSkeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331 USA ,0000 0001 2112 1969grid.4391.fCenter for Healthy Aging Research, Oregon State University, Corvallis, OR 97331 USA
| | - Russell T. Turner
- 0000 0001 2112 1969grid.4391.fSkeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331 USA ,0000 0001 2112 1969grid.4391.fCenter for Healthy Aging Research, Oregon State University, Corvallis, OR 97331 USA
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6
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McCabe IC, Fedorko A, Myers MG, Leinninger G, Scheller E, McCabe LR. Novel leptin receptor signaling mutants identify location and sex-dependent modulation of bone density, adiposity, and growth. J Cell Biochem 2018; 120:4398-4408. [PMID: 30269370 DOI: 10.1002/jcb.27726] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 08/29/2018] [Indexed: 12/27/2022]
Abstract
Leptin, a hormone primarily produced by adipocytes, contributes to the regulation of bone health by modulating bone density, growth and adiposity. Upon leptin binding, multiple sites of the long form of the leptin receptor (LepRb) are phosphorylated to trigger activation of downstream signaling pathways. To address the role of LepRb-signaling pathways in bone health, we compared the effects of three LepRb mutations on bone density, adiposity, and growth in male and female mice. The ∆65 mutation, which lacks the known tyrosine phosphorylation sites, caused obesity and the most dramatic bone phenotype marked by excessive bone adiposity, osteoporosis, and decreased growth, consistent with the phenotype of db/db and ob/ob mice that fully lack leptin receptor signaling. Mutation of LepRb Tyr 1138 , which results in an inability to recruit and phosphorylate signal transducer and activator of transcription 3, also caused obesity, but bone loss and adiposity were more dominant in male mice and no growth defect was observed. In contrast, mutation of LepRb Tyr 985 , which blocks SHP2/SOCS3 recruitment to LepRb and contributes to leptin hypersensitivity, promoted increased femur bone density only in male mice, while marrow adiposity and bone growth were not affected. Additional analyses of vertebral trabecular bone volume indicate that only the Tyr 1138 mutant mice exhibit bone loss in vertebrae. Together, our findings suggest that the phosphorylation status of specific sites of the LepRb contribute to the sex- and location-dependent bone responses to leptin. Unraveling the mechanisms by which leptin responses are sex- and location-dependent can contribute to the development of uniquely targeted osteoporosis therapies.
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Affiliation(s)
- Ian C McCabe
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Alyssa Fedorko
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Martin G Myers
- Department of Molecular and Integrative Physiology, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, Michigan.,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Gina Leinninger
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Erica Scheller
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, Saint Louis, Missouri
| | - Laura R McCabe
- Department of Physiology, Michigan State University, East Lansing, Michigan.,Department of Radiology, Michigan State University, East Lansing, Michigan.,Biomedical Imaging Research Center, Michigan State University, East Lansing, Michigan
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7
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Turner RT, Philbrick KA, Kuah AF, Branscum AJ, Iwaniec UT. Role of estrogen receptor signaling in skeletal response to leptin in female ob/ob mice. J Endocrinol 2017; 233:357-367. [PMID: 28428364 PMCID: PMC5527997 DOI: 10.1530/joe-17-0103] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/19/2017] [Indexed: 12/17/2022]
Abstract
Leptin, critical in regulation of energy metabolism, is also important for normal bone growth, maturation and turnover. Compared to wild type (WT) mice, bone mass is lower in leptin-deficient ob/ob mice. Osteopenia in growing ob/ob mice is due to decreased bone accrual, and is associated with reduced longitudinal bone growth, impaired cancellous bone maturation and increased marrow adipose tissue (MAT). However, leptin deficiency also results in gonadal dysfunction, disrupting production of gonadal hormones which regulate bone growth and turnover. The present study evaluated the role of increased estrogen in mediating the effects of leptin on bone in ob/ob mice. Three-month-old female ob/ob mice were randomized into one of the 3 groups: (1) ob/ob + vehicle (veh), (2) ob/ob + leptin (leptin) or (3) ob/ob + leptin and the potent estrogen receptor antagonist ICI 182,780 (leptin + ICI). Age-matched WT mice received vehicle. Leptin (40 µg/mouse, daily) and ICI (10 µg/mouse, 2×/week) were administered by subcutaneous injection for 1 month and bone analyzed by X-ray absorptiometry, microcomputed tomography and static and dynamic histomorphometry. Uterine weight did not differ between ob/ob mice and ob/ob mice receiving leptin + ICI, indicating that ICI successfully blocked the uterine response to leptin-induced increases in estrogen levels. Compared to leptin-treated ob/ob mice, ob/ob mice receiving leptin + ICI had lower uterine weight; did not differ in weight loss, MAT or bone formation rate; and had higher longitudinal bone growth rate and cancellous bone volume fraction. We conclude that increased estrogen signaling following leptin treatment is dispensable for the positive actions of leptin on bone and may attenuate leptin-induced bone growth.
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Affiliation(s)
- Russell T Turner
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USA
| | - Kenneth A Philbrick
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Amida F Kuah
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Adam J Branscum
- Biostatistics ProgramSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Urszula T Iwaniec
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
- Center for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USA
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8
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Abstract
The rising incidence of metabolic diseases worldwide has prompted renewed interest in the study of intermediary metabolism and cellular bioenergetics. The application of modern biochemical methods for quantitating fuel substrate metabolism with advanced mouse genetic approaches has greatly increased understanding of the mechanisms that integrate energy metabolism in the whole organism. Examination of the intermediary metabolism of skeletal cells has been sparked by a series of unanticipated observations in genetically modified mice that suggest the existence of novel endocrine pathways through which bone cells communicate their energy status to other centers of metabolic control. The recognition of this expanded role of the skeleton has in turn led to new lines of inquiry directed at defining the fuel requirements and bioenergetic properties of bone cells. This article provides a comprehensive review of historical and contemporary studies on the metabolic properties of bone cells and the mechanisms that control energy substrate utilization and bioenergetics. Special attention is devoted to identifying gaps in our current understanding of this new area of skeletal biology that will require additional research to better define the physiological significance of skeletal cell bioenergetics in human health and disease.
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Affiliation(s)
- Ryan C Riddle
- Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland; and The Baltimore Veterans Administration Medical Center, Baltimore, Maryland
| | - Thomas L Clemens
- Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland; and The Baltimore Veterans Administration Medical Center, Baltimore, Maryland
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Lindenmaier LB, Philbrick KA, Branscum AJ, Kalra SP, Turner RT, Iwaniec UT. Hypothalamic Leptin Gene Therapy Reduces Bone Marrow Adiposity in ob/ob Mice Fed Regular and High-Fat Diets. Front Endocrinol (Lausanne) 2016; 7:110. [PMID: 27579023 PMCID: PMC4985531 DOI: 10.3389/fendo.2016.00110] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/02/2016] [Indexed: 12/14/2022] Open
Abstract
Low bone mass is often associated with elevated bone marrow adiposity. Since osteoblasts and adipocytes are derived from the same mesenchymal stem cell (MSC) progenitor, adipocyte formation may increase at the expense of osteoblast formation. Leptin is an adipocyte-derived hormone known to regulate energy and bone metabolism. Leptin deficiency and high-fat diet-induced obesity are associated with increased marrow adipose tissue (MAT) and reduced bone formation. Short-duration studies suggest that leptin treatment reduces MAT and increases bone formation in leptin-deficient ob/ob mice fed a regular diet. Here, we determined the long-duration impact of increased hypothalamic leptin on marrow adipocytes and osteoblasts in ob/ob mice following recombinant adeno-associated virus (rAAV) gene therapy. Eight- to 10-week-old male ob/ob mice were randomized into four groups: (1) untreated, (2) rAAV-Lep, (3) rAAV-green fluorescent protein (rAAV-GFP), or (4) pair-fed to rAAV-Lep. For vector administration, mice were injected intracerebroventricularly with either rAAV-leptin gene therapy (rAAV-Lep) or rAAV-GFP (9 × 10(7) particles) and maintained for 30 weeks. In a second study, the impact of increased hypothalamic leptin levels on MAT was determined in mice fed high-fat diets; ob/ob mice were randomized into two groups and treated with either rAAV-Lep or rAAV-GFP. At 7 weeks post-vector administration, half the mice in each group were switched to a high-fat diet for 8 weeks. Wild-type (WT) controls included age-matched mice fed regular or high-fat diet. High-fat diet resulted in a threefold increase in MAT in WT mice, whereas MAT was increased by leptin deficiency up to 50-fold. Hypothalamic leptin gene therapy increased osteoblast perimeter and osteoclast perimeter with minor change in cancellous bone architecture. The gene therapy decreased MAT levels in ob/ob mice fed regular or high-fat diet to values similar to WT mice fed regular diet. These findings suggest that leptin plays an important role in regulating the differentiation of MSCs to adipocytes and osteoblasts, a process that may be dysregulated by high-fat diet. However, the results also illustrate that reducing MAT by increasing leptin levels does not necessarily result in increased bone mass.
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Affiliation(s)
- Laurence B. Lindenmaier
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Kenneth A. Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Satya P. Kalra
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA
- *Correspondence: Urszula T. Iwaniec,
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10
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Turner RT, Dube M, Branscum AJ, Wong CP, Olson DA, Zhong X, Kweh MF, Larkin IV, Wronski TJ, Rosen CJ, Kalra SP, Iwaniec UT. Hypothalamic leptin gene therapy reduces body weight without accelerating age-related bone loss. J Endocrinol 2015; 227:129-41. [PMID: 26487675 PMCID: PMC4917201 DOI: 10.1530/joe-15-0280] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/14/2015] [Indexed: 02/04/2023]
Abstract
Excessive weight gain in adults is associated with a variety of negative health outcomes. Unfortunately, dieting, exercise, and pharmacological interventions have had limited long-term success in weight control and can result in detrimental side effects, including accelerating age-related cancellous bone loss. We investigated the efficacy of using hypothalamic leptin gene therapy as an alternative method for reducing weight in skeletally-mature (9 months old) female rats and determined the impact of leptin-induced weight loss on bone mass, density, and microarchitecture, and serum biomarkers of bone turnover (CTx and osteocalcin). Rats were implanted with cannulae in the 3rd ventricle of the hypothalamus and injected with either recombinant adeno-associated virus encoding the gene for rat leptin (rAAV-Leptin, n=7) or a control vector encoding green fluorescent protein (rAAV-GFP, n=10) and sacrificed 18 weeks later. A baseline control group (n=7) was sacrificed at vector administration. rAAV-Leptin-treated rats lost weight (-4±2%) while rAAV-GFP-treated rats gained weight (14±2%) during the study. At study termination, rAAV-Leptin-treated rats weighed 17% less than rAAV-GFP-treated rats and had lower abdominal white adipose tissue weight (-80%), serum leptin (-77%), and serum IGF1 (-34%). Cancellous bone volume fraction in distal femur metaphysis and epiphysis, and in lumbar vertebra tended to be lower (P<0.1) in rAAV-GFP-treated rats (13.5 months old) compared to baseline control rats (9 months old). Significant differences in cancellous bone or biomarkers of bone turnover were not detected between rAAV-Leptin and rAAV-GFP rats. In summary, rAAV-Leptin-treated rats maintained a lower body weight compared to baseline and rAAV-GFP-treated rats with minimal effects on bone mass, density, microarchitecture, or biochemical markers of bone turnover.
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Affiliation(s)
- Russell T Turner
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Michael Dube
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Adam J Branscum
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Carmen P Wong
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Dawn A Olson
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Xiaoying Zhong
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Mercedes F Kweh
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Iske V Larkin
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Thomas J Wronski
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Clifford J Rosen
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Satya P Kalra
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
| | - Urszula T Iwaniec
- Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA Skeletal Biology LaboratorySchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 97331, USACenter for Healthy Aging ResearchOregon State University, Corvallis, Oregon, USADepartment of NeuroscienceMcKnight Brain Institute, University of Florida, Gainesville, Florida, USABiostatisticsSchool of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USADepartment of Physiological SciencesUniversity of Florida, Gainesville, Florida, USADepartment of Large Animal Clinical SciencesUniversity of Florida, Gainesville, Florida, USAMaine Medical Center Research InstituteScarborough, Maine, USA
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11
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Philbrick KA, Turner RT, Branscum AJ, Wong CP, Iwaniec UT. Paradoxical effects of partial leptin deficiency on bone in growing female mice. Anat Rec (Hoboken) 2015; 298:2018-29. [PMID: 26370912 DOI: 10.1002/ar.23267] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/25/2015] [Accepted: 03/24/2015] [Indexed: 11/09/2022]
Abstract
Morbidly obese, leptin-deficient ob/ob mice display low bone mass, mild osteoclast-rich osteopetrosis, and increased bone marrow adiposity. While partial leptin deficiency results in increased weight, the skeletal manifestations of partial leptin deficiency are less well defined. We therefore analyzed femora and lumbar vertebrae in growing (7-week-old) female C57BL/6 wildtype (WT) mice, partial leptin-deficient ob/+ mice, and leptin-deficient ob/ob mice. The bones were evaluated by dual energy absorptiometry, microcomputed tomography and histomorphometry. As expected, ob/+ mice were heavier, had more white adipose tissue, and lower serum leptin than WT mice, but were lighter and had less white adipose tissue than ob/ob mice. With a few exceptions, cancellous bone architecture, cell (osteoblast, osteoclast, and adipocyte), and dynamic measurements did not differ between WT and ob/+ mice. In contrast, compared to WT and ob/+ mice, ob/ob mice had lower cancellous bone volume fraction, and higher bone marrow adiposity in the femur metaphysis, and higher cancellous bone volume fraction in lumbar vertebra. Paradoxically, ob/+ mice had greater femoral bone volume than either WT or ob/ob mice. There was a positive correlation between body weight and femur volume in all three genotypes. However, the positive effect of weight on bone occurred with lower body weight in leptin-producing mice. The paradoxical differences in bone size among WT, ob/+, and ob/ob mice may be explained if leptin, in addition to stimulating bone growth and cancellous bone turnover, acts to lower the set-point at which increased body weight leads to a commensurate increase in bone size.
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Affiliation(s)
- Kenneth A Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, 97331, OR
| | - Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, 97331, OR.,Center for Healthy Aging Research, Oregon State University, Corvallis, 97331, OR
| | - Adam J Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, 97331, OR
| | - Carmen P Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, 97331, OR
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, 97331, OR.,Center for Healthy Aging Research, Oregon State University, Corvallis, 97331, OR
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12
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Zhang J, Li T, Xu L, Li W, Cheng M, Zhuang J, Chen Y, Xu W. Leptin promotes ossification through multiple ways of bone metabolism in osteoblast: a pilot study. Gynecol Endocrinol 2013; 29:758-62. [PMID: 23706140 DOI: 10.3109/09513590.2013.798278] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Leptin may be a potential option in preventing osteoporosis for menopausal women. The objective of this study is to explore the molecular mechanism of leptin on bone metabolism in osteoblast. Primary osteoblasts were isolated from parietal bone of adult female rats. mRNA level of OB-Rb in osteoblasts was inhibited by siRNA to block leptin signal transmission. The whole genome expression was tested by using gene chip to preliminarily explore the molecular mechanism of leptin in regulating osteoblast activity. The optimal concentration of siRNA was 25 nM, resulting in a maximal inhibition of OB-Rb mRNA. Ossification (p < 0.05) and bone mineralization (p = 0.0001) were downregulated by inhibiting leptin signal transmission, while bone resorption (p = 0.007), osteoblast differentiation (p = 0.026) and negative regulation of bone remodeling (p = 0.004) were upregulated. The expressions of some genes were regulated by OB-Rb siRNA. The expressions of alkaline phosphatase (p = 0.014) and osteocalcin (p = 0.002) were reduced, while that of vascular endothelial growth factor A (p = 0.0076) and IL-6 (p = 0.021) were increased. In a model of osteoblast, leptin positively promotes ossification through multiple ways including bone mineralization, remodeling, resorption and osteoblast differentiation, but which way plays the most critical role is not discussed in this study and needs to be clarified in future.
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Affiliation(s)
- Jing Zhang
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu 610041, China
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13
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Choi HJ, Ki KH, Yang JY, Jang BY, Song JA, Baek WY, Kim JH, An JH, Kim SW, Kim SY, Kim JE, Shin CS. Chronic central administration of Ghrelin increases bone mass through a mechanism independent of appetite regulation. PLoS One 2013; 8:e65505. [PMID: 23843943 PMCID: PMC3699588 DOI: 10.1371/journal.pone.0065505] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 04/25/2013] [Indexed: 12/19/2022] Open
Abstract
Leptin plays a critical role in the central regulation of bone mass. Ghrelin counteracts leptin. In this study, we investigated the effect of chronic intracerebroventricular administration of ghrelin on bone mass in Sprague-Dawley rats (1.5 μg/day for 21 days). Rats were divided into control, ghrelin ad libitum-fed (ghrelin ad lib-fed), and ghrelin pair-fed groups. Ghrelin intracerebroventricular infusion significantly increased body weight in ghrelin ad lib-fed rats but not in ghrelin pair-fed rats, as compared with control rats. Chronic intracerebroventricular ghrelin infusion significantly increased bone mass in the ghrelin pair-fed group compared with control as indicated by increased bone volume percentage, trabecular thickness, trabecular number and volumetric bone mineral density in tibia trabecular bone. There was no significant difference in trabecular bone mass between the control group and the ghrelin ad-lib fed group. Chronic intracerebroventricular ghrelin infusion significantly increased the mineral apposition rate in the ghrelin pair-fed group as compared with control. In conclusion, chronic central administration of ghrelin increases bone mass through a mechanism that is independent of body weight, suggesting that ghrelin may have a bone anabolic effect through the central nervous system.
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Affiliation(s)
- Hyung Jin Choi
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Kyoung Ho Ki
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jae-Yeon Yang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Bo Young Jang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jung Ah Song
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Wook-Young Baek
- Department of Molecular Medicine, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Korea
| | - Jung Hee Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jee Hyun An
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Sang Wan Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Seong Yeon Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jung-Eun Kim
- Department of Molecular Medicine, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Korea
| | - Chan Soo Shin
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- * E-mail:
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14
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Fazeli PK, Horowitz MC, MacDougald OA, Scheller EL, Rodeheffer MS, Rosen CJ, Klibanski A. Marrow fat and bone--new perspectives. J Clin Endocrinol Metab 2013; 98:935-45. [PMID: 23393168 PMCID: PMC3590487 DOI: 10.1210/jc.2012-3634] [Citation(s) in RCA: 286] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONTEXT There is growing interest in the relationship between bone mineral density, bone strength, and fat depots. Marrow adipose tissue, a well-established component of the marrow environment, is metabolically distinct from peripheral fat depots, but its functional significance is unknown. OBJECTIVE In this review, we discuss animal and human data linking the marrow adipose tissue depot to parameters of bone density and integrity as well as the potential significance of marrow adipose tissue in metabolic diseases associated with bone loss, including type 1 diabetes mellitus and anorexia nervosa. Potential hormonal determinants of marrow adipose tissue are also discussed. CONCLUSIONS We conclude that whereas most animal and human data demonstrate an inverse association between marrow adipose tissue and measures of bone density and strength, understanding the functional significance of marrow adipose tissue and its hormonal determinants will be critical to better understanding its role in skeletal integrity and the role of marrow adipose tissue in the pathophysiology of bone loss.
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Affiliation(s)
- Pouneh K Fazeli
- Neuroendocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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15
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Turner RT, Kalra SP, Wong CP, Philbrick KA, Lindenmaier LB, Boghossian S, Iwaniec UT. Peripheral leptin regulates bone formation. J Bone Miner Res 2013; 28:22-34. [PMID: 22887758 PMCID: PMC3527690 DOI: 10.1002/jbmr.1734] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 06/30/2012] [Accepted: 07/16/2012] [Indexed: 12/15/2022]
Abstract
Substantial evidence does not support the prevailing view that leptin, acting through a hypothalamic relay, decreases bone accrual by inhibiting bone formation. To clarify the mechanisms underlying regulation of bone architecture by leptin, we evaluated bone growth and turnover in wild-type (WT) mice, leptin receptor-deficient db/db mice, leptin-deficient ob/ob mice, and ob/ob mice treated with leptin. We also performed hypothalamic leptin gene therapy to determine the effect of elevated hypothalamic leptin levels on osteoblasts. Finally, to determine the effects of loss of peripheral leptin signaling on bone formation and energy metabolism, we used bone marrow (BM) from WT or db/db donor mice to reconstitute the hematopoietic and mesenchymal stem cell compartments in lethally irradiated WT recipient mice. Decreases in bone growth, osteoblast-lined bone perimeter and bone formation rate were observed in ob/ob mice and greatly increased in ob/ob mice following subcutaneous administration of leptin. Similarly, hypothalamic leptin gene therapy increased osteoblast-lined bone perimeter in ob/ob mice. In spite of normal osteoclast-lined bone perimeter, db/db mice exhibited a mild but generalized osteopetrotic-like (calcified cartilage encased by bone) skeletal phenotype and greatly reduced serum markers of bone turnover. Tracking studies and histology revealed quantitative replacement of BM cells following BM transplantation. WT mice engrafted with db/db BM did not differ in energy homeostasis from untreated WT mice or WT mice engrafted with WT BM. Bone formation in WT mice engrafted with WT BM did not differ from WT mice, whereas bone formation in WT mice engrafted with db/db cells did not differ from the low rates observed in untreated db/db mice. In summary, our results indicate that leptin, acting primarily through peripheral pathways, increases osteoblast number and activity.
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Affiliation(s)
- Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Satya P. Kalra
- Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, FL, 32610, USA
| | - Carmen P. Wong
- Molecular and Cellular Nutrition Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Kenneth A. Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Laurence B. Lindenmaier
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Stephane Boghossian
- Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, FL, 32610, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
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16
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Current world literature. Curr Opin Pediatr 2012; 24:770-9. [PMID: 23146873 DOI: 10.1097/mop.0b013e32835af8de] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Stunes AK, Westbroek I, Gordeladze JO, Gustafsson BI, Reseland JE, Syversen U. Systemic leptin administration in supraphysiological doses maintains bone mineral density and mechanical strength despite significant weight loss. Endocrinology 2012; 153:2245-53. [PMID: 22374968 DOI: 10.1210/en.2011-1848] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effects of leptin on bone are controversial. Although in vitro studies have shown that leptin stimulates osteoblast differentiation and mineralization and inhibits osteoclastogenesis, some rodent studies have shown that leptin administered centrally might result in decreased bone formation. In the present study we have investigated the skeletal effects of supraphysiological concentrations of leptin administered sc to rats. Female Fischer rats were given leptin 100 μg/d, 200 μg/d, or saline by continuous infusion for 9 wk. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry, bone microarchitecture was analyzed by micro-computed tomography, and biomechanical properties were tested by three-point bending experiments. At the end of the study, the body weight was significantly lower in rats receiving leptin compared with controls (-10.8% and -12.0% in low- and high-dose leptin groups, respectively). The high-dose leptin group also significantly lost weight compared with baseline. The plasma leptin concentration was 14- and 33-fold increased in the low- and high-dose groups, respectively. No significant differences in femoral BMD were observed. Whole-body BMD was significantly lower in the low-dose leptin group, whereas there was no difference between the high-dose leptin group and the control. Mechanical strength and microarchitecture were similar in the high-dose and the control group. The low-dose group, however, had decreased cortical volume in the femoral metaphysis, lowered bone strength, and altered moment of inertia. In conclusion, leptin given at very high doses maintains BMD, microarchitecture, and mechanical strength in female rats, despite a significant decrease in body weight.
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Affiliation(s)
- Astrid K Stunes
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
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18
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Motyl KJ, Rosen CJ. Understanding leptin-dependent regulation of skeletal homeostasis. Biochimie 2012; 94:2089-96. [PMID: 22534195 DOI: 10.1016/j.biochi.2012.04.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 04/10/2012] [Indexed: 02/06/2023]
Abstract
Despite growing evidence for adipose tissue regulation of bone mass, the role of the adipokine leptin in bone remodeling remains controversial. The majority of in vitro studies suggest leptin enhances osteoblastic proliferation and differentiation while inhibiting adipogenic differentiation from marrow stromal cells. Alternatively, some evidence demonstrates either no effect or a pro-apoptotic action of leptin on stromal cells. Similarly, in vivo work has demonstrated both positive and negative effects of leptin on bone mass. Most of the literature supports the idea that leptin suppresses bone mass by acting in the brainstem to reduce serotonin-dependent sympathetic signaling from the ventromedial hypothalamus to bone. However, other studies have found partly or entirely contrasting actions of leptin. Recently one study found a significant effect of surgery alone with intracerebroventricular administration of leptin, a technique crucial for understanding centrally-mediated leptin regulation of bone. Thus, two mainstream hypotheses for the role of leptin on bone emerge: 1) direct regulation through increased osteoblast proliferation and differentiation and 2) indirect suppression of bone formation through a hypothalamic relay. At the present time, it remains unclear whether these effects are relevant in only extreme circumstances (i.e. models with complete deficiency) or play an important homeostatic role in the regulation of peak bone acquisition and skeletal remodeling. Ultimately, determining the actions of leptin on the skeleton will be critical for understanding how the obesity epidemic may be impacting the prevalence of osteoporosis.
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Affiliation(s)
- Katherine J Motyl
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, USA.
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19
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Affiliation(s)
- Jeffrey M Gimble
- Stem Cell Biology Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
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20
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Jackson M, Iwaniec U, Turner R, Wronski T, Kalra S. Effects of increased hypothalamic leptin gene expression on ovariectomy-induced bone loss in rats. Peptides 2011; 32:1575-80. [PMID: 21640774 PMCID: PMC3152665 DOI: 10.1016/j.peptides.2011.04.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 01/29/2023]
Abstract
Estrogen deficiency results in accelerated bone turnover with a net increase in bone resorption. Subcutaneous administration of leptin attenuates bone loss in ovariectomized (ovx) rats by reducing bone resorption. However, in addition to its direct beneficial effects, leptin has been reported to have indirect (central nervous system-mediated) antiosteogenic effects on bone, which may limit the efficacy of elevated serum leptin to prevent estrogen deficiency-associated bone loss. The present study evaluated the long-term effects of increased hypothalamic leptin transgene expression, using recombinant adeno-associated virus-leptin (rAAV-Lep) gene therapy, on bone mass, architecture, and cellular endpoints in sexually mature ovx Sprague-Dawley rats. Ovx rats were implanted with cannulae in the 3rd ventricle of the hypothalamus and injected with either rAAV-Lep or rAAV-GFP (control vector encoding green fluorescent protein) and maintained for 10 weeks. Additional controls consisted of ovary-intact rats and ovx rats pair-fed to rAAV-Lep rats. Lumbar vertebrae were analyzed by micro-computed tomography and tibiae by histomorphometry. Cancellous bone volume was lower and osteoclast perimeter, osteoblast perimeter, and bone marrow adipocyte density were greater in ovx rats compared to ovary-intact controls. In contrast, differences among ovx groups were not detected for any endpoint evaluated. In conclusion, whereas estrogen deficiency resulted in marked cancellous osteopenia, increased bone turnover and marrow adiposity, increasing hypothalamic leptin transgene expression in ovx rats had neither detrimental nor beneficial effects on bone mass, architecture, or cellular endpoints. These findings demonstrate that the antiresorptive effects of subcutaneous leptin administration in ovx rats are mediated through leptin targets in the periphery.
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Affiliation(s)
- M.A. Jackson
- Skeletal Biology Laboratory, Oregon State University, Corvallis, OR 97331, United States
| | - U.T. Iwaniec
- Skeletal Biology Laboratory, Oregon State University, Corvallis, OR 97331, United States
- Corresponding author at: Department of Nutrition and Exercise Sciences, 108 Milam Hall, Oregon State University, Corvallis, OR 97331, United States. Tel.: +1 541 737 9925; fax: +1 541 737 6914. (U.T. Iwaniec)
| | - R.T. Turner
- Skeletal Biology Laboratory, Oregon State University, Corvallis, OR 97331, United States
| | - T.J. Wronski
- Department of Physiological Sciences, University of Florida, Gainesville, FL 2610, United States
| | - S.P. Kalra
- Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, FL 32610, United States
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