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Rabenda V, Bruyère O, Reginster JY. Risk of nonvertebral fractures among elderly postmenopausal women using antidepressants. Bone 2012; 51:674-9. [PMID: 22889722 DOI: 10.1016/j.bone.2012.07.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/29/2012] [Accepted: 07/29/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To examine the association between antidepressants, including TCAs, SSRIs, and miscellaneous antidepressants and the risk of nonvertebral fractures among women with osteoporosis. MATERIALS AND METHODS This study was a post-hoc analysis of pooled data from two international, phase III, randomized, placebo-controlled, double-blind studies (the Spinal Osteoporosis Therapeutic Intervention [SOTI] and TReatment Of Peripheral OSteoporosis [TROPOS]). A nested case-control study was performed in the placebo treated population. Adjusted logistic regression models were used to estimate the risk of nonvertebral fracture associated with the use of antidepressants. RESULTS After 3 years of follow-up, 391 nonvertebral fractures cases were identified and matched to 1955 controls. Compared with non-users of antidepressants, antidepressants use was associated with an increased risk of nonvertebral fractures (adjusted OR=1.64; 95%CI, 1.03-2.62]). Particularly, there was a 2-fold risk increase (95%CI, 1.07-3.79) of nonvertebral fracture for current users of SSRIs and a 2.1-fold risk increase for subjects who were current users of TCAs (95%CI, 1.02-4.30). Among patients categorized as recent or past users, none of the classes of antidepressants were statistically associated with increased risk of nonvertebral fracture. CONCLUSIONS Our findings confirm that both SSRIs and TCAs increase the risk of nonvertebral fracture in current users.
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Affiliation(s)
- Véronique Rabenda
- Department of Public Health, Epidemiology and Health Economics, University of Liège, Liège, Belgium.
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Sansone RA, Sansone LA. SSRIs: bad to the bone? INNOVATIONS IN CLINICAL NEUROSCIENCE 2012; 9:42-47. [PMID: 22984652 PMCID: PMC3442753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Selective serotonin reuptake inhibitors are globally popular antidepressants with broad clinical indications. Despite an overall favorable side-effect profile, our examination of 19 studies, one review, and one meta-analysis indicates that these unique antidepressants appear to have negative effects on bone, particularly with regard to bone mineral density and fracture risk. These risks may be enhanced by more serotonergic agents and/or longer exposure to selective serotonin reuptake inhibitors. The magnitude of this relationship is difficult to determine due to the myriad of potential confounds in available studies, but all indicate risk. In additional support of these findings, serotonin receptors have been identified on osteoclasts, osteoblasts, and osteocyte cell lines, suggesting that serotonin may be an important regulatory agent in bone. While no formal recommendations regarding the use of selective serotonin reuptake inhibitors in risk populations are available, caution is advised in individuals with potential risk (i.e., those with osteoporosis or histories of osteoporotic fractures).
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Affiliation(s)
- Randy A Sansone
- Departments of Psychiatry and Internal Medicine, Wright State University School of Medicine, Dayton, Ohio, USA.
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53
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Harichane Y, Dimitrova-Nakov S, Marchadier A, Collet C, Baudry A, Vidal C, Kamoun-Goldrat A, Kellermann O, Goldberg M. Enamel alterations in serotonin 2B receptor knockout mice. Eur J Oral Sci 2012; 119 Suppl 1:177-84. [PMID: 22243244 DOI: 10.1111/j.1600-0722.2011.00908.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The role of the serotonin 2B receptor (5-HT(2B) R) in enamel formation and mineralization was explored in adult 5HT(2B) R knockout (KO) mice compared with wild-type (WT) mice. In the molar, quantitative data obtained by micro-computed tomography imaging showed that the overall volume of the enamel layer was firmly reduced in KO mice. Defective mineralization was ascertained by energy-dispersive X-ray microanalysis. We also observed, using scanning electron microscopy, that parazones in the KO mice included two or three helicoidally twisted rods within Hunter-Schreger bands, instead of a single rod, as found in the WT mice. Minor disturbances were also detected in the incisors of KO mice. Structural modifications, thinner enamel crystallites, and porosities observed in KO mice indicate that the 5-HT(2B) R-mediated signaling pathways as part of the enamel formation process. These data provide a basis for evaluating the role of 5-HT(2B) R in ameloblast functions. Defects observed in the mineralization and structure of enamel in KO mice highlight that the 5-HT(2B) R interferes with the mechanisms directing amelogenesis.
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54
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Kim HY, Park MH, Yoon HK, Han KO. The changes in plasma serotonin levels after hormone therapy and their relationship with estrogen responsiveness on bone in postmenopausal women. J Clin Endocrinol Metab 2012; 97:1986-94. [PMID: 22442273 DOI: 10.1210/jc.2011-2786] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Selective serotonin reuptake inhibitors have shown to be associated with an increased risk of fractures. It has been suggested that circulating serotonin is an important regulatory factor and that estrogen may regulate bone metabolism through the serotonin pathway. OBJECTIVE Our objective was to determine the association between plasma serotonin level and bone turnover before and after hormone therapy (HT) in postmenopausal women. PARTICIPANTS AND DESIGN In this parallel comparative study using age-matched controls, 80 postmenopausal women (21 control, 59 receiving HT) aged 46-64 yr were assessed. The plasma levels of serotonin, serum concentrations of osteocalcin and carboxyterminal telopeptides, and bone mineral density (BMD) were measured at baseline and after 3 months and 1 yr of HT. RESULTS The plasma serotonin level was significantly correlated with serum total alkaline phosphatase level at baseline (r = -0.223, P = 0.048) but not with serum osteocalcin (r = -0.217, P = 0.056) or carboxyterminal telopeptides (r = -0.217, P = 0.054). There was no significant association between baseline serotonin and BMD measured at the spine or femur. The median decrements of circulating serotonin from baseline were -9.3% (interquartile range -34.0 to 53.6%) and -7.2% (-25.5 to 64.5%) at 3 months and 1 yr of HT, respectively. These changes were not significantly different from those in the control group. The short-term changes of circulating serotonin at 3 months after HT did not show significant association with the changes in BMD measured at the lumbar spine or proximal femur 1 year after HT. CONCLUSIONS Our results suggest that circulating serotonin may reflect bone turnover status, but it is not a strong enough predictor of bone loss to use as a bone marker. Moreover, serial measurements of plasma serotonin after short-term treatment with estrogen cannot predict the long-term responsiveness of bone to estrogen, suggesting that the bone-preserving effect of estrogen is independent of the peripheral action of serotonin on bone.
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Affiliation(s)
- Ha Young Kim
- Department of Endocrinology and Metabolism, Cheil General Hospital and Women's Healthcare Center, Kwandong University College of Medicine, 1-19 Mukjung Dong, Choong Gu, Seoul 100-380, Korea
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Korvala J, Jüppner H, Mäkitie O, Sochett E, Schnabel D, Mora S, Bartels CF, Warman ML, Deraska D, Cole WG, Hartikka H, Ala-Kokko L, Männikkö M. Mutations in LRP5 cause primary osteoporosis without features of OI by reducing Wnt signaling activity. BMC MEDICAL GENETICS 2012; 13:26. [PMID: 22487062 PMCID: PMC3374890 DOI: 10.1186/1471-2350-13-26] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 04/10/2012] [Indexed: 11/23/2022]
Abstract
Background Primary osteoporosis is a rare childhood-onset skeletal condition whose pathogenesis has been largely unknown. We have previously shown that primary osteoporosis can be caused by heterozygous missense mutations in the Low-density lipoprotein receptor-related protein 5 (LRP5) gene, and the role of LRP5 is further investigated here. Methods LRP5 was analyzed in 18 otherwise healthy children and adolescents who had evidence of osteoporosis (manifested as reduced bone mineral density i.e. BMD, recurrent peripheral fractures and/or vertebral compression fractures) but who lacked the clinical features of osteogenesis imperfecta (OI) or other known syndromes linked to low BMD. Also 51 controls were analyzed. Methods used in the genetic analyses included direct sequencing and multiplex ligation-dependent probe amplification (MLPA). In vitro studies were performed using luciferase assay and quantitative real-time polymerase chain reaction (qPCR) to examine the effect of two novel and three previously identified mutations on the activity of canonical Wnt signaling and on expression of tryptophan hydroxylase 1 (Tph1) and 5-hydroxytryptamine (5-Htr1b). Results Two novel LRP5 mutations (c.3446 T > A; p.L1149Q and c.3553 G > A; p.G1185R) were identified in two patients and their affected family members. In vitro analyses showed that one of these novel mutations together with two previously reported mutations (p.C913fs, p.R1036Q) significantly reduced the activity of the canonical Wnt signaling pathway. Such reductions may lead to decreased bone formation, and could explain the bone phenotype. Gut-derived Lrp5 has been shown to regulate serotonin synthesis by controlling the production of serotonin rate-limiting enzyme, Tph1. LRP5 mutations did not affect Tph1 expression, and only one mutant (p.L1149Q) reduced expression of serotonin receptor 5-Htr1b (p < 0.002). Conclusions Our results provide additional information on the role of LRP5 mutations and their effects on the development of juvenile-onset primary osteoporosis, and hence the pathogenesis of the disorder. The mutations causing primary osteoporosis reduce the signaling activity of the canonical Wnt signaling pathway and may therefore result in decreased bone formation. The specific mechanism affecting signaling activity remains to be resolved in future studies.
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Affiliation(s)
- Johanna Korvala
- Oulu Center for Cell-Matrix Research, Biocenter and Department of Medical Biochemistry and Molecular Biology, University of Oulu, Oulu, Finland
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Colón-Emeric C, O'Connell MB, Haney E. Osteoporosis piece of multi-morbidity puzzle in geriatric care. ACTA ACUST UNITED AC 2011; 78:515-26. [PMID: 21748741 DOI: 10.1002/msj.20269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Osteoporosis frequently coexists with other chronic diseases and syndromes of aging, and therefore multimorbidity interactions can potentially complicate its evaluation and treatment. This article reviews osteoporosis comorbidity interactions with select common diseases of aging including cardiovascular, neurologic, and geriatric syndromes, and select commonly used medications by older adults. Using depression as a case example, we describe the complex relationship between osteoporosis, mood, and antidepressant medications, and the implications of these interactions for patients and clinicians.
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Affiliation(s)
- Cathleen Colón-Emeric
- Duke University Medical Center and the Durham VA Geriatric Research, Education, and Clinical Center, Durham, NC, USA.
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57
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Mödder UI, Roforth MM, Hoey K, McCready LK, Peterson JM, Monroe DG, Oursler MJ, Khosla S. Effects of estrogen on osteoprogenitor cells and cytokines/bone-regulatory factors in postmenopausal women. Bone 2011; 49:202-7. [PMID: 21550429 PMCID: PMC3117945 DOI: 10.1016/j.bone.2011.04.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 04/08/2011] [Accepted: 04/17/2011] [Indexed: 12/11/2022]
Abstract
Decreases in estrogen levels contribute not only to early postmenopausal bone loss but also to bone loss with aging. While estrogen is critical for the maintenance of bone formation, the mechanism(s) of this effect remain unclear. Thus, we assessed the effects of 4months of transdermal estradiol treatment (0.05mg/day) of postmenopausal women as compared to no treatment (n=16 per group) on the expression of genes in pre-specified pathways in freshly isolated bone marrow osteoprogenitor cells (hematopoietic lineage [lin]-/Stro1+). We also evaluated whether estrogen treatment modulated peripheral blood or bone marrow plasma levels of the Wnt antagonists, sclerostin and DKK1, as well as serotonin, OPG, RANKL, adiponectin, oxytocin, and inflammatory cytokines (TNFα, IL-1β, and IL-6), as each of these molecules have recently been shown to play an important role in regulating osteoblast function and/or being responsive to estrogen. We observed a significant decrease in the expression of several proliferation markers (cyclin B1, cyclin E1, E2F1) and increase in adhesion molecules (N-cadherin) in bone marrow lin-/Stro1+ cells from estrogen-treated compared to control women. None of the peripheral blood or bone marrow plasma marker levels differed between the two groups, with the exception of sclerostin levels, which were significantly lower in the estrogen-treated as compared to the control women in peripheral serum (by 32%, P=0.009) and in bone marrow plasma (by 34%, P=0.017). There were significant differences in bone marrow versus peripheral plasma levels of several factors: sclerostin and OPG levels were higher in bone marrow as compared to peripheral plasma, whereas serotonin and adiponectin levels were higher in peripheral as compared to bone marrow plasma. In summary, our data directly assessing possible regulation by estrogen of osteoprogenitor cells in humans indicate that, consistent with previous studies in mice, estrogen suppresses the proliferation of human bone marrow lin-/Stro1+ cells, which likely represent early osteoprogenitor cells. Further animal and human studies are needed to define the role of the changes we observed in mRNAs for adhesion molecules in these cells and in local sclerostin production in bone in mediating the effects of estrogen on bone metabolism in humans.
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Affiliation(s)
- Ulrike I Mödder
- Endocrine Research Unit, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Diem SJ, Blackwell TL, Stone KL, Cauley JA, Hillier TA, Haney EM, Ensrud KE. Use of antidepressant medications and risk of fracture in older women. Calcif Tissue Int 2011; 88:476-84. [PMID: 21455735 PMCID: PMC3542967 DOI: 10.1007/s00223-011-9481-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/19/2011] [Indexed: 11/25/2022]
Abstract
Use of antidepressant medications has been associated with increased risk of fracture, but prior studies have been limited by incomplete control of confounders or a limited number of fractures. Use of antidepressant medications by 8,217 community-dwelling women aged 69 and older from a population-based prospective cohort study at four US clinical centers was assessed by interview at four examinations over a 10-year period, beginning in 1992-1994. Use was coded as a time-dependent variable. Incident fractures occurring after the initial medication assessment until July 2007 were confirmed by radiographic reports. Potential confounders were included in multivariable models and updated at each follow-up visit. Compared to nonusers of antidepressant medications, women using SSRIs experienced a higher risk of nonspine fracture in age-adjusted models (HR = 1.36, 95% CI 1.11-1.67) and in multivariable models controlling for potential confounders (HR = 1.30, 95% CI 1.04-1.62). SSRI use was not associated with an increased risk of first hip fracture (HR = 1.01, 95% CI 0.71-1.44) but was associated with an increased risk of wrist fracture (HR = 1.54, 95% CI 1.01-2.36). TCA use was associated with an increased risk of nonspine fracture in age-adjusted models, but in multivariable models this risk was attenuated. SSRI use was associated with a higher risk of any nonspine fracture, but not hip fracture, in this cohort of older women. TCA use was associated with a higher risk of nonspine fracture, but this association was in part explained by confounding factors.
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Affiliation(s)
- Susan J. Diem
- Department of Medicine and Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN
| | | | - Katie L. Stone
- California Pacific Medical Center Research Institute, San Francisco, CA
| | - Jane A. Cauley
- Division of Epidemiology, University of Pittsburgh, Pittsburgh, PA
| | | | - Elizabeth M. Haney
- Department of Medicine, Oregon Health & Science University, Portland, OR
| | - Kristine E. Ensrud
- Department of Medicine and Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN
- Center for Chronic Disease Outcomes Research, Veterans Affairs Medical Center, Minneapolis, MN
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Zikan V. Bone health in patients with multiple sclerosis. J Osteoporos 2011; 2011:596294. [PMID: 21603140 PMCID: PMC3096310 DOI: 10.4061/2011/596294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/02/2011] [Indexed: 01/23/2023] Open
Abstract
Multiple sclerosis (MS) is a gait disorder characterized by acute episodes of neurological defects leading to progressive disability. Patients with MS have multiple risk factors for osteoporotic fractures, such as progressive immobilization, long-term glucocorticoids (GCs) treatment or vitamin D deficiency. The duration of motor disability appears to be a major contributor to the reduction of bone strength. The long term immobilization causes a marked imbalance between bone formation and resorption with depressed bone formation and a marked disruption of mechanosensory network of tightly connected osteocytes due to increase of osteocyte apoptosis. Patients with higher level of disability have also higher risk of falls that combined with a bone loss increases the frequency of bone fractures. There are currently no recommendations how to best prevent and treat osteoporosis in patients with MS. However, devastating effect of immobilization on the skeleton in patients with MS underscores the importance of adequate mechanical stimuli for maintaining the bone structure and its mechanical competence. The physical as well as pharmacological interventions which can counteract the bone remodeling imbalance, particularly osteocyte apoptosis, will be promising for prevention and treatment of osteoporosis in patients with MS.
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Affiliation(s)
- Vit Zikan
- Department of Internal Medicine 3, Faculty of Medicine 1, Charles University, 128 00 Prague, Czech Republic
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60
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Li WF, Hou SX, Yu B, Jin D, Férec C, Chen JM. Genetics of osteoporosis: perspectives for personalized medicine. Per Med 2010; 7:655-668. [PMID: 29788568 DOI: 10.2217/pme.10.55] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Osteoporosis is the most common metabolic bone disorder worldwide. At least 15 genes (e.g., ESR1, LRP5, SOST, OPG, RANK and RANKL) have been confirmed as osteoporosis susceptibility genes, and another 30 have been highlighted as promising susceptibility genes. Notably, these genes are clustered in three biological pathways: the estrogen endocrine pathway, the Wnt/β-catenin signaling pathway and the RANK/RANKL/osteoprotegerin (OPG) pathway. In this article, using data pertaining to these three biological pathways as examples, we illustrate possible principles of personalized therapy for osteoporosis. In particular, we propose to use inhibitors (e.g., denosumab) of the RANK/RANKL/OPG signaling pathway to circumvent resistance to estrogen-replacement therapy: a novel idea resulting from the consideration of a mechanistic link between the estrogen endocrine pathway and the RANK/RANKL/OPG signaling pathway. In addition, we call for more attention to be focused on rare variants of major effects in future studies.
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Affiliation(s)
- Wen-Feng Li
- Department of Orthopaedics, The First Affiliated Hospital, General Hospital of the People’s Liberation Army, Beijing, China
| | - Shu-Xun Hou
- Department of Orthopaedics, The First Affiliated Hospital, General Hospital of the People’s Liberation Army, Beijing, China
| | - Bin Yu
- Department of Orthopaedic Trauma, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Dan Jin
- Department of Orthopaedic Trauma, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Claude Férec
- Institut National de la Santé et de la Recherche Médicale (INSERM), U613, Brest, France; INSERM, U613 and EFS – Bretagne, 46 rue Félix Le Dantec, 29218 Brest, France
- Etablissement Français du Sang (EFS) – Bretagne, Brest, France
- Faculté de Médecine et des Sciences de la Santé, Université de Bretagne Occidentale (UBO), Brest, France
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Abstract
CONTEXT Serotonin (5-HT) may be an important regulatory agent in bone, and agents that modify 5-HT signaling, such as selective serotonin reuptake inhibitors (SSRIs), are in widespread clinical use. EVIDENCE ACQUISITION Evidence was obtained by PubMed search and the author's knowledge of the field. EVIDENCE SYNTHESIS Recent data suggest that gut-derived 5-HT may mediate the skeletal effects of LDL receptor-related protein 5, stimulating intense interest in a novel mechanism for regulating bone mass. However, the specific biochemical nature of serotonergic pathways influencing bone and their direct and/or indirect effects on bone metabolism are still unclear. The weight of epidemiological evidence suggests that SSRIs are associated with reduced bone mass, increased bone loss, and increased risk of fractures. Interpretation of these studies is complicated by the confounding effects of depression, the usual indication for treatment with SSRIs. The mechanisms for putative SSRI-induced deleterious effects on the skeleton are unknown, and are likely multifactorial. CONCLUSIONS 5-HT may have regulatory effects on bone. Initial preclinical data suggest that its effects may be deleterious and may be regulated by low-density lipoprotein receptor-related protein 5. These studies need confirmation, as well as elucidation, of the biochemical pathways utilized and the feedback loops involved among bone, gut, and perhaps brain. Paradoxically, targeting of 5-HT synthesis and/or signaling in selective tissues may hold promise as an anabolic intervention for bone. Epidemiological data suggest that clinicians should be vigilant about detection of bone disease in patients who are using SSRIs.
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Affiliation(s)
- Michael Bliziotes
- Department of Medicine, Oregon Health & Science University and Portland VA Medical Center, Portland, Oregon 97239, USA.
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62
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Abstract
Wnt signaling is involved not only in embryonic development but also in maintenance of
homeostasis in postnatal tissues. Multiple lines of evidence have increased understanding
of the roles of Wnt signaling in bone since mutations in the LRP5 gene
were identified in human bone diseases. Canonical Wnt signaling promotes mesenchymal
progenitor cells to differentiate into osteoblasts. The canonical Wnt/β-catenin pathway
possibly through Lrp6, a co-receptor for Wnts as well as Lrp5, in osteoblasts regulates
bone resorption by increasing the OPG/RANKL ratio. However, endogenous inhibitors of Wnt
signaling including sclerostin block bone formation. Regulation of sclerostin appears to
be one of the mechanisms of PTH anabolic actions on bone. Since sclerostin is almost
exclusively expressed in osteocytes, inhibition of sclerostin is the most promising
design. Surprisingly, Lrp5 controls bone formation by inhibiting serotonin synthesis in
the duodenum, but not by directly promoting bone formation. Pharmacological intervention
may be considered in many components of the canonical Wnt signaling pathway, although
adverse effects and tumorigenicity to other tissues are important. More studies will be
needed to fully understand how the Wnt signaling pathway actually influences bone
metabolism and to assure the safety of new interventions.
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Affiliation(s)
- Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan ; Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
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Komatsu DE, Warden SJ. The control of fracture healing and its therapeutic targeting: improving upon nature. J Cell Biochem 2010; 109:302-11. [PMID: 19950200 DOI: 10.1002/jcb.22418] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Fracture repair is a complex process involving timed cellular recruitment, gene expression, and synthesis of compounds that regenerate native tissue to restore the mechanical integrity, and thus function of injured bone. While the majority of fractures heal without complication, this takes time and a subset of patients ( approximately 10%) experience healing delays, extending their morbidity and treatment costs. Consequently, there is a need for efficacious therapeutics for the intervention of fracture healing. Recent studies into the molecular control of fracture repair and advances in the understanding of the skeleton as a whole have resulted in the identification of numerous novel targets and compounds for such intervention. These include traditional agents such bone morphogenetic proteins and other growth factors, but also relatively newer compounds such as parathyroid hormone and modulators of the Wnt signaling pathway. These agents, along with others, are discussed in the current article in terms of their investigative status and potential for clinical implementation. Hopefully, these agents, as well as others yet to be discovered, will demonstrate sufficient clinical utility for successful intervention of fracture healing. This may have significant implications for the duration of morbidity and costs associated with traumatic bone fractures.
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Affiliation(s)
- David E Komatsu
- InMotion Orthopaedic Research Center, Memphis, Tennessee, USA.
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Baudry A, Bitard J, Mouillet-Richard S, Locker M, Poliard A, Launay JM, Kellermann O. Serotonergic 5-HT(2B) receptor controls tissue-nonspecific alkaline phosphatase activity in osteoblasts via eicosanoids and phosphatidylinositol-specific phospholipase C. J Biol Chem 2010; 285:26066-73. [PMID: 20573958 DOI: 10.1074/jbc.m109.073791] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In previous studies, we observed that mice knocked out for the serotonin-2B receptor (5-HT(2B)R) show defects in bone homeostasis. The present work focuses on the downstream targets relaying the anabolic function of this receptor in osteoblasts. A functional link between the 5-HT(2B)R and the activity of the tissue-nonspecific alkaline phosphatase (TNAP) is established using the C1 osteoprogenitor cell line. During C1 osteogenic differentiation, both 5-HT(2B)R and TNAP mRNA translations are delayed with respect to extracellular matrix deposition. Once the receptor is expressed, it constitutively controls TNAP activity at a post-translational level along the overall period of mineral deposition. Indeed, pharmacological inhibition of the 5-HT(2B)R intrinsic activity or shRNA-mediated 5-HT(2B)R knockdown prevents TNAP activation, but not its mRNA translation. In contrast, agonist stimulation of the receptor further increases TNAP activity during the initial mineralization phase. Building upon our previous observations that the 5-HT(2B)R couples with the phospholipase A2 pathway and prostaglandin production at the beginning of mineral deposition, we show that the 5-HT(2B)R controls leukotriene synthesis via phospholipase A2 at the terminal stages of C1 differentiation. These two 5-HT(2B)R-dependent eicosanoid productions delineate distinct time windows of TNAP regulation during the osteogenic program. Finally, prostaglandins or leukotrienes are shown to relay the post-translational activation of TNAP via stimulation of the phosphatidylinositol-specific phospholipase C. In agreement with the above findings, primary calvarial osteoblasts from 5-HT(2B)R-null mice exhibit defects in TNAP activity.
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Affiliation(s)
- Anne Baudry
- Cellules Souches, Signalisation et Prions, INSERM U747, Université Paris Descartes, Paris, France
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Warden SJ, Hassett SM, Bond JL, Rydberg J, Grogg JD, Hilles EL, Bogenschutz ED, Smith HD, Fuchs RK, Bliziotes MM, Turner CH. Psychotropic drugs have contrasting skeletal effects that are independent of their effects on physical activity levels. Bone 2010; 46:985-92. [PMID: 20060080 PMCID: PMC2842446 DOI: 10.1016/j.bone.2009.12.031] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 11/01/2009] [Accepted: 12/29/2009] [Indexed: 11/23/2022]
Abstract
Popular psychotropic drugs, like the antidepressant selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), and the mood stabilizer lithium, may have skeletal effects. In particular, preclinical observations suggest a direct negative effect of SSRIs on the skeleton. A potential caveat in studies of the skeletal effects of psychotropic drugs is the hypoactive (skeletal unloading) phenotype they induce. The aim of this study was to investigate the contribution of physical inactivity to the skeletal effects of psychotropic drugs by studying bone changes in cage control and tail suspended mice treated with either vehicle, SSRI, TCA or lithium. Tail suspension was used to control for drug differences on physical activity levels by normalizing skeletal loading between groups. The psychotropic drugs were found to have contrasting skeletal effects which were independent of drug effects on animal physical activity levels. The latter was evident by an absence of statistical interactions between the activity and drug groups. Pharmacological inhibition of the 5-hydroxytryptamine (5-HT) transporter (5-HTT) using a SSRI reduced in vivo gains in lower extremity BMD, and negatively altered ex vivo measures of femoral and spinal bone density, architecture and mechanical properties. These effects were mediated by a decrease in bone formation without a change in bone resorption suggesting that the SSRI had anti-anabolic skeletal effects. In contrast, glycogen synthase kinase-3[beta] (GSK-3[beta]) inhibition using lithium had anabolic effects improving in vivo gains in BMD via an increase in bone formation, while TCA-mediated inhibition of the norepinephrine transporter had minimal skeletal effect. The observed negative skeletal effect of 5-HTT inhibition, combined with recent findings of direct and indirect effects of 5-HT on bone formation, are of interest given the frequent prescription of SSRIs for the treatment of depression and other affective disorders. Likewise, the anabolic effect of GSK-3[beta] inhibition using lithium reconfirms the importance of Wnt/beta-catenin signaling in the skeleton and it's targeting by recent drug discovery efforts. In conclusion, the current study demonstrates that different psychotropic drugs with differing underlying mechanisms of action have contrasting skeletal effects and that these effects do not result indirectly via the generation of animal physical inactivity.
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Affiliation(s)
- Stuart J Warden
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA.
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Haney EM, Warden SJ, Bliziotes MM. Effects of selective serotonin reuptake inhibitors on bone health in adults: time for recommendations about screening, prevention and management? Bone 2010; 46:13-7. [PMID: 19664737 PMCID: PMC3413453 DOI: 10.1016/j.bone.2009.07.083] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 07/16/2009] [Accepted: 07/24/2009] [Indexed: 01/01/2023]
Abstract
Evidence regarding a functional serotonin (5-hydroxytryptamine) signaling system in bone has generated considerable recent interest. The specific biochemical nature of serotoninergic pathways and their direct and/or indirect effects on bone metabolism are still unclear. Clinical evidence supports an effect of serotonin and altered serotonin signaling on bone metabolism. Serotonin is involved in the pathophysiology of depression, and therefore studies of depression and antidepressant treatments (as modulators of the serotonin system) are relevant with regard to bone outcomes. Studies on the effect of depression on bone mineral density (BMD) and fractures have been mixed. Studies on the associations between antidepressant use and BMD and/or fractures are more consistent. SSRIs have been associated with lower BMD and increased rates of bone loss, as well as increased rates of fracture after accounting for falls. These studies are limited by confounding because depression is potentially associated with both the outcome of interest (BMD and fracture) and the exposure (SSRIs). With mounting evidence for an effect on bone, this review considers the question of causality and whether selective serotonin reuptake inhibitors should be considered among those medications that contribute to bone loss, and therefore prompt clinicians to evaluate BMD proactively. Future research will be required to confirm the serotoninergic effects on bone and the biochemical pathways involved, and to identify clinical implications for treatment based on this novel pathway.
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Affiliation(s)
- Elizabeth M Haney
- Department of Medicine, Oregon Health and Science University, Portland, OR 97239, USA.
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N-cadherin negatively regulates osteoblast proliferation and survival by antagonizing Wnt, ERK and PI3K/Akt signalling. PLoS One 2009; 4:e8284. [PMID: 20011526 PMCID: PMC2788421 DOI: 10.1371/journal.pone.0008284] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 10/29/2009] [Indexed: 12/31/2022] Open
Abstract
Background Osteoblasts are bone forming cells that play an essential role in osteogenesis. The elucidation of the mechanisms that control osteoblast number is of major interest for the treatment of skeletal disorders characterized by abnormal bone formation. Canonical Wnt signalling plays an important role in the control of osteoblast proliferation, differentiation and survival. Recent studies indicate that the cell-cell adhesion molecule N-cadherin interacts with the Wnt co-receptors LRP5/6 to regulate osteoblast differentiation and bone accrual. The role of N-cadherin in the control of osteoblast proliferation and survival remains unknown. Methods and Principal Findings Using murine MC3T3-E1 osteoblastic cells and N-cadherin transgenic mice, we demonstrate that N-cadherin overexpression inhibits cell proliferation in vitro and in vivo. The negative effect of N-cadherin on cell proliferation results from decreased Wnt, ERK and PI3K/Akt signalling and is restored by N-cadherin neutralizing antibody that antagonizes N-cadherin-LRP5 interaction. Inhibition of Wnt signalling using DKK1 or Sfrp1 abolishes the ability of N-cadherin blockade to restore ERK and PI3K signalling and cell proliferation, indicating that the altered cell growth in N-cadherin overexpressing cells is in part secondary to alterations in Wnt signalling. Consistently, we found that N-cadherin overexpression inhibits the expression of Wnt3a ligand and its downstream targets c-myc and cyclin D1, an effect that is partially reversed by N-cadherin blockade. We also show that N-cadherin overexpression decreases osteoblast survival in vitro and in vivo. This negative effect on cell survival results from inhibition of PI3K/Akt signalling and increased Bax/Bcl-2, a mechanism that is rescued by Wnt3a. Conclusion The data show that N-cadherin negatively controls osteoblast proliferation and survival via inhibition of autocrine/paracrine Wnt3a ligand expression and attenuation of Wnt, ERK and PI3K/Akt signalling, which provides novel mechanisms by which N-cadherin regulates osteoblast number.
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