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Cheng L, Wang S. Lower serum testosterone is associated with increased likelihood of arthritis. Sci Rep 2023; 13:19241. [PMID: 37935765 PMCID: PMC10630339 DOI: 10.1038/s41598-023-46424-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 10/31/2023] [Indexed: 11/09/2023] Open
Abstract
Studies have suggested that serum testosterone levels may be strongly correlated with the pathogenesis of arthritis. Therefore, the aim of this study was to assess the relationship between serum testosterone levels and arthritis in US adults using the National Health and Nutrition Examination Survey (NHANES). We used the database from NHANES, 2013-2016 to perform a cross-sectional study. This study investigated the relationship between serum testosterone and arthritis using multivariate logistic regression models and also used smoothed curve fitting and generalized additivity models. A total of 10,439 adults were included in this analysis. A significant negative association between serum testosterone and arthritis was found in a linear regression analysis. The study showed that the arthritis group had lower testosterone levels than the non-arthritis group. The univariate multivariate analyses of Q4, using Q1 as a reference, all showed a significantly lower risk of developing arthritis. In subgroup analyses, the negative correlation between serum testosterone levels and arthritis was more significant in women and those with a body mass index (BMI) ≥ 30 kg/m2. After controlling for various variables, we found a significant association between serum testosterone and arthritis in this analysis. Further study of the relationship between testosterone and arthritis is necessary to clarify the specific mechanism of serum testosterone action on arthritis.
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Affiliation(s)
- Lulu Cheng
- College of Acupuncture-Moxibustion and Tuina, Anhui University of Chinese Medicine, Hefei, 230012, China.
- Graduate School, Wuhan Sports University, Wuhan, 430079, China.
| | - Siyu Wang
- Graduate School, Wuhan Sports University, Wuhan, 430079, China
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2
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Patel J, Chen S, Katzmeyer T, Pei YA, Pei M. Sex-dependent variation in cartilage adaptation: from degeneration to regeneration. Biol Sex Differ 2023; 14:17. [PMID: 37024929 PMCID: PMC10077643 DOI: 10.1186/s13293-023-00500-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/20/2023] [Indexed: 04/08/2023] Open
Abstract
Despite acknowledgement in the scientific community of sex-based differences in cartilage biology, the implications for study design remain unclear, with many studies continuing to arbitrarily assign demographics. Clinically, it has been well-established that males and females differ in cartilage degeneration, and accumulating evidence points to the importance of sex differences in the field of cartilage repair. However, a comprehensive review of the mechanisms behind this trend and the influence of sex on cartilage regeneration has not yet been presented. This paper aims to summarize current findings regarding sex-dependent variation in knee anatomy, sex hormones' effect on cartilage, and cartilaginous degeneration and regeneration, with a focus on stem cell therapies. Findings suggest that the stem cells themselves, as well as their surrounding microenvironment, contribute to sex-based differences. Accordingly, this paper underscores the contribution of both stem cell donor and recipient sex to sex-related differences in treatment efficacy. Cartilage regeneration is a field that needs more research to optimize strategies for better clinical results; taking sex into account could be a big factor in developing more effective and personalized treatments. The compilation of this information emphasizes the importance of investing further research in sex differences in cartilage biology.
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Affiliation(s)
- Jhanvee Patel
- Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, 64 Medical Center Drive, PO Box 9196, Morgantown, WV, 26506-9196, USA
| | - Song Chen
- Department of Orthopaedics, The General Hospital of Western Theater Command, Chengdu, 610083, Sichuan, China
| | - Torey Katzmeyer
- Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, 64 Medical Center Drive, PO Box 9196, Morgantown, WV, 26506-9196, USA
| | - Yixuan Amy Pei
- Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, 64 Medical Center Drive, PO Box 9196, Morgantown, WV, 26506-9196, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ming Pei
- Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, 64 Medical Center Drive, PO Box 9196, Morgantown, WV, 26506-9196, USA.
- WVU Cancer Institute, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV, 26506, USA.
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Joshua Cohen D, ElBaradie K, Boyan BD, Schwartz Z. Sex-specific effects of 17β-estradiol and dihydrotestosterone (DHT) on growth plate chondrocytes are dependent on both ERα and ERβ and require palmitoylation to translocate the receptors to the plasma membrane. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:159028. [PMID: 34416391 DOI: 10.1016/j.bbalip.2021.159028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/19/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022]
Abstract
Rat costochondral cartilage growth plate chondrocytes exhibit cell sex-specific responses to 17β-estradiol (E2), testosterone, and dihydrotestosterone (DHT). Mechanistically, E2 and DHT stimulate proliferation and extracellular matrix synthesis in chondrocytes from female and male rats, respectively, by signaling through protein kinase C (PKC) and phospholipase C (PLC). Estrogen receptors (ERα; ERβ) and androgen receptors (ARs) are present in both male and female cells, but it is not known whether they interact to elicit sex-specific signaling. We used specific agonists and antagonists of these receptors to examine the relative contributions of ERs and ARs in membrane-mediated E2 signaling in female chondrocytes and DHT signaling in male chondrocytes. PKC activity in female chondrocytes was stimulated by agonists of ERα and ERβ and required intact caveolae; PKC activity was inhibited by the E2 enantiomer and by an inhibitor of ERβ. Western blots of cell lysates co-immunoprecipitated for ERα suggested the formation of a complex containing both ERα and ERß with E2 treatment. DHT and DHT agonists activated PKC in male cells, while AR inhibition blocked the stimulatory effect of DHT on PKC. Inhibition of ERα and ERβ also blocked PKC activation by DHT. Western blots of whole-cell lysates, plasma membranes, and caveolae indicated the translocation of AR to the plasma membrane and specifically to caveolae with DHT treatment. These results suggest that E2 and DHT promote chondrocyte differentiation via the ability of ARs and ERs to form a complex. The results also indicate that intact caveolae and palmitoylation of the membrane receptor(s) or membrane receptor complex containing ERα and ERβ is required for E2 and DHT membrane-associated PKC activity in costochondral cartilage cells.
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Affiliation(s)
- D Joshua Cohen
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
| | - Khairat ElBaradie
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30033, USA
| | - Barbara D Boyan
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30033, USA.
| | - Zvi Schwartz
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; Department of Periodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Wu YT, Tang MX, Wang YJ, Li J, Wang YX, Deng A, Guo CF, Zhang HQ. Lower androgen levels promote abnormal cartilage development in female patients with adolescent idiopathic scoliosis. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:784. [PMID: 34268397 PMCID: PMC8246169 DOI: 10.21037/atm-20-3171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 01/25/2021] [Indexed: 11/14/2022]
Abstract
Background Adolescent idiopathic scoliosis (AIS) is a disease characterized by changes in the three-dimensional structure of the spine. Studies have shown that the development of AIS might be associated with genetic, biomechanics, endocrine factors and abnormal bone or cartilage development. Methods Blood samples collected from 301 female patients (161 females with AIS and 140 females without AIS) were used for genotyping. Forty-eight serum samples from 161 females with AIS and 40 serum samples from 140 females without AIS were subjected to enzyme-linked immunosorbent assays (ELISAs). We also evaluated 32 facet joints (18 females with AIS and 14 females without AIS from the 301 female patients) using immunohistochemistry, Western blotting, and isolation of human primary chondrocytes, among other methods. We treated the AIS primary chondrocytes with dihydrotestosterone (DHT) to verify the relationship among androgen, the androgen receptor (AR), and its downstream pathway proteins. Results The serum androgen level in the AIS group was significantly decreased (1.94±0.09 vs. 2.284±0.103) compared with that in the non-AIS (control) group. The single nucleotide polymorphism genotyping results showed that the mutation rates of rs6259 between the AIS and control groups were significantly different (G/G genotype: 48.4% vs. 42.1%, G/A genotype: 40.4% vs. 35.7%, P<0.05). The levels of interleukin (IL)-6 and metalloproteinase (MMP)-13 were increased in the cartilage of AIS patients, and these patients also exhibited decreased AR levels. The cell experiment results showed that androgen reduced the degree of abnormal cartilage development in female AIS patients through the AR/IL-6/signal transducer and activator of transcription 3 (STAT3) signaling pathway. Conclusions Our study provides a new perspective on the pathogenesis of AIS and indicates that decreased androgen levels in female AIS patients play a potential role in the development of AIS via the AR/IL-6/STAT3 signaling pathway.
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Affiliation(s)
- Yuan-Tao Wu
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Department of Spine Surgery, Hainan General Hospital and Hainan Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Ming-Xing Tang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yun-Jia Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jiong Li
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yu-Xiang Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Ang Deng
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Chao-Feng Guo
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Hong-Qi Zhang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
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Robitaille J, Langlois VS. Consequences of steroid-5α-reductase deficiency and inhibition in vertebrates. Gen Comp Endocrinol 2020; 290:113400. [PMID: 31981690 DOI: 10.1016/j.ygcen.2020.113400] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/13/2020] [Accepted: 01/20/2020] [Indexed: 01/16/2023]
Abstract
In 1974, a lack of 5α-dihydrotestosterone (5α-DHT), the most potent androgen across species except for fish, was shown to be the origin of a type of pseudohermaphrodism in which boys have female-like external genitalia. This human intersex condition is linked to a mutation in the steroid-5α-reductase type 2 (SRD5α2) gene, which usually produces an important enzyme capable of reducing the Δ4-ene of steroid C-19 and C-21 into a 5α-stereoisomer. Seeing the potential of SRD5α2 as a target for androgen synthesis, pharmaceutical companies developed 5α-reductase inhibitors (5ARIs), such as finasteride (FIN) and dutasteride (DUT) to target SRD5α2 in benign prostatic hyperplasia and androgenic alopecia. In addition to human treatment, the development of 5ARIs also enabled further research of SRD5α functions. Therefore, this review details the morphological, physiological, and molecular effects of the lack of SRD5α activity induced by both SRD5α mutations and inhibitor exposures across species. More specifically, data highlights 1) the role of 5α-DHT in the development of male secondary sexual organs in vertebrates and sex determination in non-mammalian vertebrates, 2) the role of SRD5α1 in the synthesis of the neurosteroid allopregnanolone (ALLO) and 5α-androstane-3α,17β-diol (3α-diol), which are involved in anxiety and sexual behavior, respectively, and 3) the role of SRD5α3 in N-glycosylation. This review also features the lesser known functions of SRD5αs in steroid degradation in the uterus during pregnancy and glucocorticoid clearance in the liver. Additionally, the review describes the regulation of SRD5αs by the receptors of androgens, progesterone, estrogen, and thyroid hormones, as well as their differential DNA methylation. Factors known to be involved in their differential methylation are age, inflammation, and mental stimulation. Overall, this review helps shed light on the various essential functions of SRD5αs across species.
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Affiliation(s)
- Julie Robitaille
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Quebec City, QC, Canada
| | - Valerie S Langlois
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Quebec City, QC, Canada.
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Baron J, Sävendahl L, De Luca F, Dauber A, Phillip M, Wit JM, Nilsson O. Short and tall stature: a new paradigm emerges. Nat Rev Endocrinol 2015; 11:735-46. [PMID: 26437621 PMCID: PMC5002943 DOI: 10.1038/nrendo.2015.165] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In the past, the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis was often considered to be the main system that regulated childhood growth and, therefore, determined short stature and tall stature. However, findings have now revealed that the GH-IGF-1 axis is just one of many regulatory systems that control chondrogenesis in the growth plate, which is the biological process that drives height gain. Consequently, normal growth in children depends not only on GH and IGF-1 but also on multiple hormones, paracrine factors, extracellular matrix molecules and intracellular proteins that regulate the activity of growth plate chondrocytes. Mutations in the genes that encode many of these local proteins cause short stature or tall stature. Similarly, genome-wide association studies have revealed that the normal variation in height seems to be largely due to genes outside the GH-IGF-1 axis that affect growth at the growth plate through a wide variety of mechanisms. These findings point to a new conceptual framework for understanding short and tall stature that is centred not on two particular hormones but rather on the growth plate, which is the structure responsible for height gain.
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Affiliation(s)
- Jeffrey Baron
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Lars Sävendahl
- Division of Pediatric Endocrinology, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Francesco De Luca
- St. Christopher’s Hospital for Children, Section of Endocrinology and Diabetes; Drexel University College of Medicine, Department of Pediatrics, Philadelphia, PA, U.S.A
| | - Andrew Dauber
- Cincinnati Center for Growth Disorders, Cincinnati Children’s Hospital Medical Center, Division of Endocrinology, Cincinnati, Ohio, USA
| | - Moshe Phillip
- The Jesse Z and Sara Lea Shafer Institute for Endocrinology and Diabetes, National Center for Children’s Diabetes, Schneider Children’s Medical Center of Israel, Petah Tikva, Israel
| | - Jan M. Wit
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ola Nilsson
- Division of Pediatric Endocrinology, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
- Center for Molecular Medicine, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
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Fernandes GS, Valdes AM. Cardiovascular disease and osteoarthritis: common pathways and patient outcomes. Eur J Clin Invest 2015; 45:405-14. [PMID: 25630589 DOI: 10.1111/eci.12413] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/25/2015] [Indexed: 12/29/2022]
Abstract
BACKGROUND Osteoarthritis (OA) and cardiovascular disease (CVD) are the two most prevalent conditions in the population aged over 70 in developed countries. Both conditions share common risk factors, in particular age and body mass index. However, the very high level of co-occurrence of both diseases cannot be accounted by common risk factors alone. MATERIALS AND METHODS We reviewed the recent literature published in English in PubMed for articles relating to osteoarthritis and cardiovascular disease. RESULTS On the one hand, the disability caused by OA increases the risk of CVD and in particular of ischemic events and mortality beyond what can be explained by known common risk factors, such as ageing and obesity. Moreover, the presence of OA has a synergistic effect on CVD symptoms considerably worsening them. On the other hand, at least in women, there appears to be a common pathogenic mechanism underlying atherosclerosis (but not hypertension) and actual joint damage. CONCLUSION There are some possible molecular mechanisms underlying both diseases, in particular relating to low grade inflammation and female hormones. However, the data available to date also indicate that OA may be considered as an indirect cause of CVD by increasing walking disability and the use of analgesic medication such as NSAIDs. We discuss future directions that need to be taken to address these highly prevalent, costly and disabling morbidities.
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Ultrastructure of Intervertebral Disc and Vertebra-Disc Junctions Zones as a Link in Etiopathogenesis of Idiopathic Scoliosis. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/850594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Background Context. There is no general accepted theory on the etiology of idiopathic scoliosis (IS). An important role of the vertebrae endplate physes (VEPh) and intervertebral discs (IVD) in spinal curve progression is acknowledged, but ultrastructural mechanisms are not well understood. Purpose. To analyze the current literature on ultrastructural characteristics of VEPh and IVD in the context of IS etiology. Study Design/Setting. A literature review. Results. There is strong evidence for multifactorial etiology of IS. Early wedging of vertebra bodies is likely due to laterally directed appositional bone growth at the concave side, caused by a combination of increased cell proliferation at the vertebrae endplate and altered mechanical properties of the outer annulus fibrosus of the adjacent IVD. Genetic defects in bending proteins necessary for IVD lamellar organization underlie altered mechanical properties. Asymmetrical ligaments, muscular stretch, and spine instability may also play roles in curve formation. Conclusions. Development of a reliable, cost effective method for identifying patients at high risk for curve progression is needed and could lead to a paradigm shift in treatment options. Unnecessary anxiety, bracing, and radiation could potentially be minimized and high risk patient could receive surgery earlier, rendering better outcomes with fewer fused segments needed to mitigate curve progression.
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Vicente WS, dos Reis LM, Graciolli RG, Graciolli FG, Dominguez WV, Wang CC, Fonseca TL, Velosa AP, Roschel H, Teodoro WR, Gualano B, Jorgetti V. Bone plasticity in response to exercise is sex-dependent in rats. PLoS One 2013; 8:e64725. [PMID: 23741378 PMCID: PMC3669412 DOI: 10.1371/journal.pone.0064725] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/17/2013] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To characterize the potential sexual dimorphism of bone in response to exercise. METHODS Young male and female Wistar rats were either submitted to 12 weeks of exercise or remained sedentary. The training load was adjusted at the mid-trial (week 6) by the maximal speed test. A mechanical test was performed to measure the maximal force, resilience, stiffness, and fracture load. The bone structure, formation, and resorption were obtained by histomorphometric analyses. Type I collagen (COL I) mRNA expression and tartrate-resistant acid phosphatase (TRAP) mRNA expression were evaluated by quantitative real-time PCR (qPCR). RESULTS The male and female trained rats significantly improved their maximum speed during the maximal exercise test (main effect of training; p<0.0001). The male rats were significantly heavier than the females, irrespective of training (main effect of sex; p<0.0001). Similarly, both the weight and length of the femur were greater for the male rats when compared with the females (main effect of sex; p<0.0001 and p<0.0001, respectively). The trabecular volume was positively affected by exercise in male and female rats (main effect of training; p = 0.001), whereas the trabecular thickness, resilience, mineral apposition rate, and bone formation rate increased only in the trained males (within-sex comparison; p<0.05 for all parameters), demonstrating the sexual dimorphism in response to exercise. Accordingly, the number of osteocytes increased significantly only in the trained males (within-sex comparison; p<0.05). Pearson's correlation analyses revealed that the COL I mRNA expression and TRAP mRNA expression were positively and negatively, respectively, related to the parameters of bone remodeling obtained from the histomorphometric analysis (r = 0.59 to 0.85; p<0.05). CONCLUSION Exercise yielded differential adaptations with respect to bone structure, biomechanical proprieties, and molecular signaling in male and female rats.
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Affiliation(s)
- Wagner S. Vicente
- Nephrology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | - Luciene M. dos Reis
- Nephrology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | - Rafael G. Graciolli
- Nephrology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | | | - Wagner V. Dominguez
- Nephrology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | - Charles C. Wang
- Department of Physiological Sciences, Federal University of São Carlos, São Paulo, Brazil
| | - Tatiana L. Fonseca
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Ana P. Velosa
- Rheumatology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | - Hamilton Roschel
- Department of Sports, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Walcy R. Teodoro
- Rheumatology Division, Medical School, University of São Paulo, São Paulo, Brazil
| | - Bruno Gualano
- Department of Sports, School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
| | - Vanda Jorgetti
- Nephrology Division, Medical School, University of São Paulo, São Paulo, Brazil
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10
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Elbaradie KB, Wang Y, Boyan BD, Schwartz Z. Sex-specific response of rat costochondral cartilage growth plate chondrocytes to 17β-estradiol involves differential regulation of plasma membrane associated estrogen receptors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1165-72. [DOI: 10.1016/j.bbamcr.2012.12.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/29/2012] [Accepted: 12/30/2012] [Indexed: 12/17/2022]
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11
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Boyan BD, Hart DA, Enoka RM, Nicolella DP, Resnick E, Berkley KJ, Sluka KA, Kwoh CK, Tosi LL, O'Connor MI, Coutts RD, Kohrt WM. Hormonal modulation of connective tissue homeostasis and sex differences in risk for osteoarthritis of the knee. Biol Sex Differ 2013; 4:3. [PMID: 23374322 PMCID: PMC3583799 DOI: 10.1186/2042-6410-4-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 12/10/2012] [Indexed: 12/24/2022] Open
Abstract
Young female athletes experience a higher incidence of ligament injuries than their male counterparts, females experience a higher incidence of joint hypermobility syndrome (a risk factor for osteoarthritis development), and post-menopausal females experience a higher prevalence of osteoarthritis than age-matched males. These observations indicate that fluctuating sex hormone levels in young females and loss of ovarian sex hormone production due to menopause likely contribute to observed sex differences in knee joint function and risk for loss of function. In studies of osteoarthritis, however, there is a general lack of appreciation for the heterogeneity of hormonal control in both women and men. Progress in this field is limited by the relatively few preclinical osteoarthritis models, and that most of the work with established models uses only male animals. To elucidate sex differences in osteoarthritis, it is important to examine sex hormone mechanisms in cells from knee tissues and the sexual dimorphism in the role of inflammation at the cell, tissue, and organ levels. There is a need to determine if the risk for loss of knee function and integrity in females is restricted to only the knee or if sex-specific changes in other tissues play a role. This paper discusses these gaps in knowledge and suggests remedies.
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Affiliation(s)
- Barbara D Boyan
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 315 Ferst Drive NW, Atlanta, GA 30332-0363, USA
| | - David A Hart
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Roger M Enoka
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Daniel P Nicolella
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Eileen Resnick
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Karen J Berkley
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Kathleen A Sluka
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - C Kent Kwoh
- University of Pittsburgh and Pittsburgh VA Healthcare System, Pittsburgh, PA, USA.,Epidemiology, and Clinical and Translational Science Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, University of Pittsburgh Arthritis Institute, Pittsburgh, USA
| | - Laura L Tosi
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Mary I O'Connor
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA.,Mayo Clinic, 4500 San Pablo Road, Jacksonville, Florida, USA
| | - Richard D Coutts
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
| | - Wendy M Kohrt
- Isis Research Network on Musculoskeletal Health, Society for Women's Health Research, 1025 Connecticut Avenue, NW Suite 601, Washington, DC, 20036, USA
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Linn S, Murtaugh B, Casey E. Role of sex hormones in the development of osteoarthritis. PM R 2012; 4:S169-73. [PMID: 22632696 DOI: 10.1016/j.pmrj.2012.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 01/25/2012] [Indexed: 10/28/2022]
Abstract
Women older than 50 years have a considerably higher prevalence of osteoarthritis than men of the same age group. Although several factors have been proposed, there is some evidence that sex hormones influence the development of osteoarthritis. This article will focus on the basic science and clinical evidence that describe the current state of knowledge regarding the relationship between sex hormones and the development of osteoarthritis.
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Affiliation(s)
- Sarah Linn
- Department of Physical Medicine and Rehabilitation, Rehabilitation Institute of Chicago, Chicago, IL, USA
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ElBaradie K, Wang Y, Boyan BD, Schwartz Z. Rapid membrane responses to dihydrotestosterone are sex dependent in growth plate chondrocytes. J Steroid Biochem Mol Biol 2012; 132:15-23. [PMID: 22207084 DOI: 10.1016/j.jsbmb.2011.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 12/05/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
Sex steroids are important regulators for longitudinal growth, bone mass accrual, and sexual dimorphism of the skeleton. 17β-Estradiol regulates proliferation and differentiation of female chondrocytes via a membrane-associated signaling pathway in addition to its estrogen receptor (ER) mediated effects. In contrast, testosterone does not elicit a similar membrane response, either in male or female cells. Whereas female rat growth plate chondrocytes convert testosterone to 17β-estradiol, male chondrocytes produce 5α-dihydrotestosterone (DHT). Previously DHT was found to mediate sex-specific effects of testosterone in male cells, but it is not known if a membrane-signaling pathway is involved. In this study, we hypothesized that DHT can induce sex-specific rapid membrane effects similar to other steroid hormones. Confluent cultures of chondrocytes isolated from resting zones of growth plates of both male and female rats were treated with 10(-10)-10(-7)M testosterone or DHT for 3, 9, 90 and 270min and protein kinase C (PKC) and phospholipase A2 (PLA2) activities were measured. To examine potential signaling pathways involved in PKC activation, male chondrocytes were treated with 10(-7)M DHT for 9min in the presence or absence of the phospholipase C (PLC) inhibitor U73122, the secretory PLA2 inhibitor quinacrine or the cytosolic PLA2 inhibitor AACOCF3; the Gαi inhibitor pertussis toxin (PTX) or Gαs activator cholera toxin (CTX), and the general G-protein inhibitor GDPβS; thapsigargin, an inhibitor of a Ca-ATPase pump in the endoplasmic reticulum; verapamil and nifedipine, inhibitors of specific L type Ca2+ channels on the cell membrane; and cyproterone acetate (CPA), which is an inhibitor of the classical androgen receptor (AR); as well as the transcription inhibitor actinomycin D, or the translation inhibitor cycloheximide. DHT induced a dose-dependent increase in PKC and PLA2 activity in male cells with the highest increase at 10(-7)M DHT (p<0.05), whereas testosterone had no effect. PKC activity was augmented at 9 and 90 min, and then decreased to baseline at 270min. Neither testosterone nor DHT affected PKC in female cells. U73122, quinacrine, and AACOCF3 inhibited DHT-induced activation of PKC. DHT treatment for 9 min had no effect in [(3)H]-thymidine incorporation in quiescent confluent cultures but caused a dose dependent increase in alkaline phosphatase specific activity. Inhibition of PLC reduced the response of to DHT in a dose dependent manner, indicating that PLC is involved. In conclusion, our study indicates that DHT, but not testosterone, has sex-specific rapid membrane effects in male growth plate chondrocytes involving PLC and PLA2-mediated PKC signaling pathways. Together with previous observations showing that male cells convert testosterone to DHT, these results suggest that DHT might act in the membrane through an autocrine/paracrine mechanism.
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Affiliation(s)
- Khairat ElBaradie
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
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14
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Abstract
5α-Reduced glucocorticoids (GCs) are formed when one of the two isozymes of 5α-reductase reduces the Δ(4-5) double bond in the A-ring of GCs. These steroids are largely viewed inert, despite the acceptance that other 5α-dihydro steroids, e.g. 5α-dihydrotestosterone, retain or have increased activity at their cognate receptors. However, recent findings suggest that 5α-reduced metabolites of corticosterone have dissociated actions on GC receptors (GRs) in vivo and in vitro and are thus potential candidates for safer anti-inflammatory steroids. 5α-Dihydro- and 5α-tetrahydro-corticosterone can bind with GRs, but interest in these compounds had been limited, since they only weakly activated metabolic gene transcription. However, a greater understanding of the signalling mechanisms has revealed that transactivation represents only one mode of signalling via the GR and recently the abilities of 5α-reduced GCs to suppress inflammation have been demonstrated in vitro and in vivo. Thus, the balance of parent GC and its 5α-reduced metabolite may critically affect the profile of GR signalling. 5α-Reduction of GCs is up-regulated in liver in metabolic disease and may represent a pathway that protects from both GC-induced fuel dyshomeostasis and concomitant inflammatory insult. Therefore, 5α-reduced steroids provide hope for drug development, but may also act as biomarkers of the inflammatory status of the liver in metabolic disease. With these proposals in mind, careful attention must be paid to the possible adverse metabolic effects of 5α-reductase inhibitors, drugs that are commonly administered long term for the treatment of benign prostatic hyperplasia.
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Affiliation(s)
- Mark Nixon
- Endocrinology, Queen's Medical Research Institute, University/British Heart Foundation Centre for Cardiovascular Science, Edinburgh EH16 4TJ, UK
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15
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Dy CJ, LaMont LE, Ton QV, Lane JM. Sex and gender considerations in male patients with osteoporosis. Clin Orthop Relat Res 2011; 469:1906-12. [PMID: 21400003 PMCID: PMC3111783 DOI: 10.1007/s11999-011-1849-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Osteoporosis remains underrecognized and undertreated in both men and women, but men who sustain fragility fractures experience greater morbidity and mortality. While men exhibit advanced comorbidity at the time of hip fracture presentation, there are distinct sex- and gender-specific factors related to the pathophysiology and treatment of osteoporosis that further influence morbidity and mortality. QUESTIONS/PURPOSES With a selective review of the literature, we evaluated sex- and gender-based differences contributing to increased morbidity and mortality in men with osteoporosis. WHERE ARE WE NOW?: Sex-specific differences in bone biology and morphology may affect the pathophysiology of osteoporosis, choice of pharmacotherapy, and surgical implant selection. Additionally, estrogen metabolism may play a key role in both fracture prevention and healing. Gender-based differences in recommendations for screening and prevention between men and women may influence the severity at which osteoporosis is recognized. Primary, secondary, and tertiary prevention efforts in men lag behind those of women. This may be due to a lack of consensus regarding screening guidelines for osteoporosis in men but may be attributed to lack of awareness in the physician and patient about osteoporosis and its potentially debilitating consequences. WHERE DO WE NEED TO GO?: These disparities are a call to action for healthcare providers to raise awareness for early prevention and treatment of this potentially debilitating disease, particularly in men. HOW DO WE GET THERE?: Continued prospective research on the differences between men and women diagnosed with osteoporosis is needed, as well as sex-specific stratification of data in all studies on osteoporosis.
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Affiliation(s)
- Christopher J. Dy
- Department of Orthopaedic Surgery, Hospital for Special Surgery and Weill Cornell Medical College, 535 E 70th Street, New York, NY 10021 USA
| | - Lauren E. LaMont
- Department of Orthopaedic Surgery, Hospital for Special Surgery and Weill Cornell Medical College, 535 E 70th Street, New York, NY 10021 USA
| | - Quang V. Ton
- Department of Orthopaedic Surgery, Hospital for Special Surgery and Weill Cornell Medical College, 535 E 70th Street, New York, NY 10021 USA
| | - Joseph M. Lane
- Department of Orthopaedic Surgery, Hospital for Special Surgery and Weill Cornell Medical College, 535 E 70th Street, New York, NY 10021 USA
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16
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Bairey Merz CN, Mark S, Boyan BD, Jacobs AK, Shah PK, Shaw LJ, Taylor D, Marbán E. Proceedings from the scientific symposium: Sex differences in cardiovascular disease and implications for therapies. J Womens Health (Larchmt) 2010; 19:1059-72. [PMID: 20500123 PMCID: PMC2940456 DOI: 10.1089/jwh.2009.1695] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED A consortium of investigator-thought leaders was convened at the Heart Institute at Cedars-Sinai Medical Center and produced the following summary points: POINT 1: Important sex differences exist in cardiovascular disease (CVD) that affect disease initiation, diagnosis, and treatment. IMPLICATION Research that acknowledges these differences is needed to optimize outcomes in women and men. POINT 2: Atherosclerosis is qualitatively and quantitatively different in women and men; women demonstrate more plaque erosion and more diffuse plaque with less focal artery lumen intrusion. IMPLICATION Evaluation of CVD strategies that include devices should be used to explore differing anatomical shapes and surfaces as well as differing drug coating and eluting strategies. POINT 3: Bone marrow progenitor cells (PCs) engraft differently based on the sex of the donor cell and the sex of the recipient. IMPLICATION PC therapeutic studies need to consider the sex of cells of the source and the recipient. POINT 4: Women have a greater risk of venous but not arterial thrombosis compared with men, as well as more bleeding complications related to anticoagulant treatment. Several genes coding for proteins involved in hemostasis are regulated by sex hormones. IMPLICATIONS Research should be aimed at evaluation of sex-based differences in response to anticoagulation based on genotype. POINT 5: Women and men can have differences in pharmacological response. IMPLICATION Sex-specific pharmacogenomic studies should be included in pharmacological development. POINT 6: CVD progression results from an imbalance of cell injury and repair in part due to insufficient PC repair, which is affected by sex differences, where females have higher circulating levels of PCs with greater rates of tissue repair. IMPLICATION CVD regenerative strategies should be directed at learning to deliver cells that shift the recipient balance from injury toward repair. CVD repair strategies should ideally be tested first in females to have the best chance of success for proof-of-concept.
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Affiliation(s)
- C Noel Bairey Merz
- Women's Heart Center, Cedars-Sinai Heart Institute, 444 S. San Vincente Boulevard, Los Angeles, CA 90048, USA.
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17
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Rejtarová O, Hejna P, Soukup T, Kuchař M. Age and sexually dimorphic changes in costal cartilages. A preliminary microscopic study. Forensic Sci Int 2009; 193:72-8. [DOI: 10.1016/j.forsciint.2009.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 09/09/2009] [Accepted: 09/16/2009] [Indexed: 01/08/2023]
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Abstract
Longitudinal growth, which is primarily due to chondrocytic activity at the level of the epiphyseal growth plate, is influenced by many hormones and growth factors in an endocrine and paracrine manner. Their influence is even more complex during the accelerated growth period of puberty that accounts for about 20% of final adult height. Although abnormalities of growth during puberty are very common, the underlying mechanisms that govern the beginning and cessation of pubertal growth at the level of the growth plate are poorly understood. Sex steroids play a crucial role in pubertal growth both at the systemic level via the GH/IGF-1 axis and at the local level of the epiphyseal growth plate. In both sexes it is now accepted that oestrogen is the critical hormone in controlling growth plate acceleration and fusion. This paper reviews the mechanisms that influence pubertal growth and the problems that are associated with disorders of gonadal function.
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Affiliation(s)
- R J Perry
- Bone & Endocrine Research Group, Royal Hospital for Sick Children, Glasgow, UK.
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19
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Ma HL, Blanchet TJ, Peluso D, Hopkins B, Morris EA, Glasson SS. Osteoarthritis severity is sex dependent in a surgical mouse model. Osteoarthritis Cartilage 2007; 15:695-700. [PMID: 17207643 DOI: 10.1016/j.joca.2006.11.005] [Citation(s) in RCA: 242] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 11/18/2006] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the role of sex hormones in cartilage degradation and progression of osteoarthritis (OA) in a murine model induced by destabilization of the medial meniscus (DMM). DESIGN Accelerated OA development in mice was induced by transection of the menisco-tibial ligament, which anchors the medial meniscus to the tibial plateau. Intact male and female, and orchiectomized (ORX) male and ovariectomized (OVX) female mouse knee histology were compared for signs of OA following DMM. The effect of testosterone or estrogen addition in vivo was assessed in ORX males in the surgical OA model. RESULTS OA severity was markedly higher in males than females after DMM. OVX females developed significantly more severe OA than control females. ORX males developed significantly less severe OA than control males. When ORX male mice were supplemented with exogenous dihydrotestosterone (DHT), the severity of OA was restored to the level experienced by the control male mice. Hip cartilage from mice of both sexes demonstrated similar spontaneous and interleukin-1alpha (IL-1alpha) induced proteoglycan (PG) release in vitro. DHT and 17-beta estradiol (E2) did not significantly alter the PG release pattern when supplemented to cartilage cultures of either sex. CONCLUSION Sex hormones play a critical role in the progression of OA in the murine DMM surgical model, with males having more severe OA than females. Intact females had more OA than OVX females, indicating that ovarian hormones decrease the severity of OA in the female mice. Male hormones, such as testosterone, exacerbate OA in male mice as demonstrated by the fact that ORX mice experienced less OA than intact males, and that addition of DHT to ORX males was able to counteract the effect of castration and re-establish severe OA.
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Affiliation(s)
- H-L Ma
- Wyeth, Women's Health and Musculoskeletal Biology, Cambridge, MA 02140, USA
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20
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Hanna FS, Bell RJ, Cicuttini FM, Davison SL, Wluka AE, Davis SR. The relationship between endogenous testosterone, preandrogens, and sex hormone binding globulin and knee joint structure in women at midlife. Semin Arthritis Rheum 2007; 37:56-62. [PMID: 17303218 DOI: 10.1016/j.semarthrit.2006.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2006] [Revised: 11/09/2006] [Accepted: 12/23/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To evaluate the relationship between serum testosterone (T), preandrogens and sex hormone binding globulin (SHBG), and the knee structure in middle-aged women without knee pain. METHODS One hundred and thirty-nine healthy women without knee pain, aged 40 to 67 years, underwent magnetic resonance imaging of their dominant knee to measure tibial and patella cartilage volumes and defects, respective bone area and volume, and bone marrow lesions. The serum level of T, preandrogens, and SHBG were analyzed using linear regression to determine whether associations existed between these hormones and knee structure. RESULTS Free T and total T showed no association with cartilage volume or bone structures in the knee. SHBG showed a statistically positive association with patella bone volume after adjusting for confounders (P = 0.02). CONCLUSION Our study suggests there are no associations between serum levels of T or the preandrogens and knee structure in women. The observed positive association between SHBG and patella bone volume may reflect a favorable effect of estrogen exposure on patella bone volume.
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Affiliation(s)
- F S Hanna
- Women's Health Program, Department of Medicine, Central and Eastern Clinical School, Monash University, Alfred Hospital, Prahran, Victoria, Australia
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Kinney RC, Schwartz Z, Week K, Lotz MK, Boyan BD. Human articular chondrocytes exhibit sexual dimorphism in their responses to 17beta-estradiol. Osteoarthritis Cartilage 2005; 13:330-7. [PMID: 15780646 DOI: 10.1016/j.joca.2004.12.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2004] [Accepted: 12/11/2004] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The higher incidence of osteoarthritis in females suggests that there may be intrinsic sex-specific differences in human articular chondrocytes. 17beta-Estradiol (E2) regulates rat growth plate chondrocytes through traditional nuclear receptor mechanisms, but only female cells exhibit rapid membrane-associated effects mediated through protein kinase C (PKC) alpha. Here we demonstrate sexual dimorphism in the physiological response of human articular chondrocytes to E2. METHODS Articular chondrocytes were obtained at the time of autopsy from three male and three female donors between 16 and 39 years of age. Second passage cultures were treated with E2 for 24 h to assess the effects of the hormone on [3H]-thymidine incorporation, [35S]-sulfate incorporation, and alkaline phosphatase specific activity. In addition, the chondrocytes were treated for 3, 9, 90 or 270 min and PKC specific activity was determined. RESULTS All chondrocytes were positive for aggrecan and estrogen receptor alpha mRNAs but were negative for type II collagen mRNA. Only cells from female donors responded to E2. DNA synthesis, sulfate incorporation and alkaline phosphatase activity were increased. E2 caused a rapid increase in PKC activity in the female cells within 9 min that was maximal at 90 min. Treatment with the PKC inhibitor chelerythrine blocked these effects. CONCLUSIONS These results provide the first definitive evidence that normal human cells exhibit an intrinsic sex-specific response to E2 and suggest that sexual dimorphism may be an important variable in assessing the pathways that modulate cell behavior.
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Affiliation(s)
- R C Kinney
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, GA 30332, USA
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