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Abstract
Gonadotropins are glycoprotein sex hormones regulating development and reproduction and bind to specific G protein–coupled receptors expressed in the gonads. Their effects on multiple signaling cascades and intracellular events have recently been characterized using novel technological and scientific tools. The impact of allosteric modulators on gonadotropin signaling, the role of sugars linked to the hormone backbone, the detection of endosomal compartments supporting signaling modules, and the dissection of different effects mediated by these molecules are areas that have advanced significantly in the last decade. The classic view providing the exclusive activation of the cAMP/protein kinase A (PKA) and the steroidogenic pathway by these hormones has been expanded with the addition of novel signaling cascades as determined by high-resolution imaging techniques. These new findings provided new potential therapeutic applications. Despite these improvements, unanswered issues of gonadotropin physiology, such as the intrinsic pro-apoptotic potential to these hormones, the existence of receptors assembled as heteromers, and their expression in extragonadal tissues, remain to be studied. Elucidating these issues is a challenge for future research.
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Affiliation(s)
- Livio Casarini
- Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Via G. Campi 287, 41125 Modena, Italy
- Center for Genomic Research, University of Modena and Reggio Emilia, Via G. Campi 287, 41125 Modena, Italy
| | - Manuela Simoni
- Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Via G. Campi 287, 41125 Modena, Italy
- Center for Genomic Research, University of Modena and Reggio Emilia, Via G. Campi 287, 41125 Modena, Italy
- Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria di Modena, Via P. Giardini 1355, 41126 Modena, Italy
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Fröhlich E, Wahl R. MECHANISMS IN ENDOCRINOLOGY: Impact of isolated TSH levels in and out of normal range on different tissues. Eur J Endocrinol 2016; 174:R29-41. [PMID: 26392471 DOI: 10.1530/eje-15-0713] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 09/18/2015] [Indexed: 12/20/2022]
Abstract
Routine treatment of thyroid cancer (TC) includes long-term suppression of TSH. The necessity of this treatment in low- and intermediate-risk patients as well as the extent of TSH suppression is currently under discussion. A literature search was performed to illustrate the role of TSH in extrathyroidal cells and to identify potential reasons for different effects of exogenously suppressed and endogenously low TSH levels. Although adverse effects of subnormal and supranormal TSH blood levels on heart and brain have not been consistently found, studies show a clear negative effect of suppressed TSH levels on bone mineral density. Experimental data also support an important role of TSH in the immune system. The ability of levothyroxine (l-T4) to regulate TSH levels and triiodothyronine levels in a physiological manner is limited. Reduction of circadian changes in TSH levels, decrease of thyroid hormone-binding proteins, prevention of potential compensatory increases of TSH levels (e.g., in old age), and unresponsiveness of TSH-producing cells to TRH on l-T4 treatment might cause adverse effects of suppressed TSH levels. In view of the adverse effects of aggressive TSH suppression, achieving the suggested levels of TSH between 0.9 and 1 mU/l in the treatment of low-to-intermediate risk TC patients appears justified.
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Affiliation(s)
| | - Richard Wahl
- Center for Medical ResearchMedical University of Graz, Stiftingtalstraße 24, Graz, AustriaInternal Medicine (Department of EndocrinologyMetabolism, Nephrology and Clinical Chemistry), University of Tuebingen, Otfried-Muellerstrasse 10, Tuebingen, Germany
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Follicle-Stimulating Hormone Increases the Risk of Postmenopausal Osteoporosis by Stimulating Osteoclast Differentiation. PLoS One 2015; 10:e0134986. [PMID: 26241313 PMCID: PMC4524683 DOI: 10.1371/journal.pone.0134986] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 07/15/2015] [Indexed: 11/22/2022] Open
Abstract
Objective The objectives of this study were to observe the changes in follicle-stimulating hormone (FSH) and bone mineral density (BMD) in postmenopausal women, to research the relationship between FSH and postmenopausal osteoporosis, and to observe the effects of FSH on osteoclast differentiation in RAW264.7 cells. Methods We analyzed 248 postmenopausal women with normal bone metabolism. A radioimmunoassay (RIA) was used to detect serum FSH, luteinizing hormone (LH), and estradiol (E2). Dual-energy X-ray absorptiometry was used to measure forearm BMD. Then, we analyzed the age-related changes in serum FSH, LH and E2. Additionally, FSH serum concentrations were compared between a group of postmenopausal women with osteoporosis and a control group. Osteoclasts were induced from RAW264.7 cells in vitro by receptor activator of nuclear factor kappa B ligand (RANKL), and these cells were treated with 0, 5, 10, and 20 ng/ml FSH. After the osteoclasts matured, tartrate-resistant acid phosphatase (TRAP) staining was used to identify osteoclasts, and the mRNA expression levels of genes involved in osteoclastic phenotypes and function, such as receptor activator of NF-κB (Rank), Trap, matrix metalloproteinase-9 (Mmp-9) and Cathepsin K, were detected in different groups using real-time PCR (polymerase chain reaction). Results 1. FSH serum concentrations in postmenopausal women with osteoporosis increased notably compared with the control group. 2. RANKL induced RAW264.7 cell differentiation into mature osteoclasts in vitro. 3. FSH increased mRNA expression of genes involved in osteoclastic phenotypes and function, such as Rank, Trap, Mmp-9 and Cathepsin K, in a dose-dependent manner. Conclusions The circulating concentration of FSH may play an important role in the acceleration of bone loss in postmenopausal women. FSH increases osteoclastogenesis in vitro.
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Faienza MF, Luce V, Lonero A, Ventura A, Colaianni G, Colucci S, Cavallo L, Grano M, Brunetti G. Treatment of osteoporosis in children with glucocorticoid-treated diseases. Expert Rev Endocrinol Metab 2014; 9:525-534. [PMID: 30736214 DOI: 10.1586/17446651.2014.936384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glucocorticoid induced osteoporosis (GIO) is the most frequent form of drug induced osteoporosis. Glucocorticoids affect osteoblastogenesis, osteoclastogenesis and promote the apoptosis of osteoblasts and osteocytes. A decrease of bone mineral density has been described in several pediatric diseases that require glucocorticoids, both as long-term replacement therapy, such as Congenital Adrenal Hyperplasia, and as treatment of acute phase or relapses, such as asthma, juvenile rheumatoid arthritis, inflammatory bowel diseases, systemic lupus erythematosus, organ transplantation and Steroid Sensitive Nephrotic Syndrome. The increasing number of children with GIO and at risk of fractures reflects the complex nature of this condition, and the need of development of anti-osteoporotic drugs. In this review, we focus on the mechanisms of GIO in some pediatric diseases and on treatment of osteoporosis. We also report data on new signaling pathways as potential targets for future anti-osteoporotic drugs.
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Affiliation(s)
- Maria Felicia Faienza
- a Section of Pediatrics, Department of Biomedical Sciences and Human Oncology, University "A. Moro", Bari, Italy
| | - Vincenza Luce
- a Section of Pediatrics, Department of Biomedical Sciences and Human Oncology, University "A. Moro", Bari, Italy
| | - Antonella Lonero
- a Section of Pediatrics, Department of Biomedical Sciences and Human Oncology, University "A. Moro", Bari, Italy
| | - Annamaria Ventura
- a Section of Pediatrics, Department of Biomedical Sciences and Human Oncology, University "A. Moro", Bari, Italy
| | - Graziana Colaianni
- b Section of Human Anatomy and Histology, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Silvia Colucci
- b Section of Human Anatomy and Histology, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Luciano Cavallo
- a Section of Pediatrics, Department of Biomedical Sciences and Human Oncology, University "A. Moro", Bari, Italy
| | - Maria Grano
- b Section of Human Anatomy and Histology, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Giacomina Brunetti
- b Section of Human Anatomy and Histology, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
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Uihlein AV, Finkelstein JS, Lee H, Leder BZ. FSH suppression does not affect bone turnover in eugonadal men. J Clin Endocrinol Metab 2014; 99:2510-5. [PMID: 24646101 PMCID: PMC4079307 DOI: 10.1210/jc.2013-3246] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT In vitro and animal studies have reported conflicting results regarding an independent role for FSH in the regulation of bone turnover. OBJECTIVE Our objective was to test the hypothesis that suppressing serum FSH while holding serum gonadal steroid levels stable in the eugonadal range will affect biochemical markers of bone metabolism in healthy men. PARTICIPANTS, DESIGN, AND SETTING Eugonadal men aged 20 to 50 years participated in this randomized controlled trial at a tertiary care academic teaching hospital. INTERVENTIONS Participants received monthly GnRH analog injections to suppress FSH secretion plus daily topical testosterone gel in prespecified doses (intervention group). Controls received matching placebos (control group). Subjects in the intervention group were individually matched with subjects in the control group to ensure that the mean testosterone and estradiol levels (measured every 4 weeks during the 16-week study period) in the 2 groups were similar. MAIN OUTCOME MEASURES Biochemical markers of bone resorption (serum N-terminal telopeptide and C-terminal telopeptide), bone formation (serum osteocalcin), and FSH were measured at baseline and after 16 weeks of treatment. RESULTS Serum FSH declined by 2% in the control group and by 60% in the intervention group (P < .0001 for the between-group difference). Despite the substantial suppression of serum FSH in the intervention group, serum N-terminal telopeptide, C-terminal telopeptide, and osteocalcin did not change in the intervention group, nor were any between-group differences observed. CONCLUSION When gonadal steroid levels are held constant, short-to midterm suppression of FSH does not affect bone turnover in men. FSH does not appear to be a significant regulator of bone metabolism in eugonadal men.
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Affiliation(s)
- Alexander V Uihlein
- Endocrine Unit (A.V.U., J.S.F., B.Z.L.) and Biostatistics Center (H.L.), Massachusetts General Hospital, Boston, Massachusetts 02114
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Abstract
Osteoporosis is less common in individuals with high fat mass. This putative osteoprotection is likely an adaptive mechanism that allows obese individuals to better carry their increased body mass. Recent studies have focused on hormones that link fat to bone. Adipokines, such as leptin, modulate bone cells through both direct and indirect actions, whereas molecules activating peroxisome proliferator-activated receptor γ drive mesenchymal stem cell differentiation towards adipocytes away from the osteoblastic lineage. There is emerging evidence that bone-derived osteocalcin regulates insulin release and insulin sensitivity and, hence, might indirectly affect fat mass. Despite these molecular connections between fat and bone, animal and human studies call into question a primary role for body fat in determining bone mass. Mice devoid of fat do not have a skeletal phenotype, and in humans, the observed correlations between bone and body mass are not just due to adipose tissue. An improved understanding of the integrative physiology at the fat-bone interface should allow us develop therapies for both osteoporosis and obesity.
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Affiliation(s)
- Mone Zaidi
- Mount Sinai Bone Program and Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA.
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Moore DJ, Gonzales JU, Tucker SH, Elavsky S, Proctor DN. Exercise-induced vasodilation is associated with menopause stage in healthy middle-aged women. Appl Physiol Nutr Metab 2012; 37:418-24. [PMID: 22486379 DOI: 10.1139/h2012-015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leg exercise hemodynamics during single-leg knee extensions were compared among healthy groups of early perimenopausal (n = 15), late perimenopausal (n = 12), and early postmenopausal (n = 11) women. Femoral blood flow (FBF) and vascular conductance (FVC) at rest and during very light work rates (0 and 5 W) were similar among all three menopause stage groups. Vascular responses at 10 W (FBF) and 20 W (FBF and FVC) were significantly higher (P < 0.05) in early perimenopausal compared with late perimenopausal women. At 15 and 25 W, FBF and FVC were similar between late perimenopausal and early postmenopausal groups but higher (P < 0.05) in early perimenopausal women as compared with the other two menopausal groups. In the combined sample of all three menopause stage groups, follicle-stimulating hormone was significantly correlated with vascular conductance during submaximal (15 W) exercise (R = -0.56, P < 0.001), even after adjustment for age, fitness, LDL cholesterol, and abdominal fat (R = -0.46, P = 0.005). Collectively, these findings suggest that in middle-aged women, there is an association between menopause stage and leg vascular responsiveness during exercise.
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Affiliation(s)
- David J Moore
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
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Lukefahr AL, Frye JB, Wright LE, Marion SL, Hoyer PB, Funk JL. Decreased bone mineral density in rats rendered follicle-deplete by an ovotoxic chemical correlates with changes in follicle-stimulating hormone and inhibin A. Calcif Tissue Int 2012; 90:239-49. [PMID: 22249524 PMCID: PMC3288225 DOI: 10.1007/s00223-011-9565-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 12/23/2011] [Indexed: 10/14/2022]
Abstract
Bone loss during perimenopause, an estrogen-sufficient period, correlates with elevated serum follicle-stimulating hormone (FSH) and decreased inhibins A and B. Utilizing a recently described ovotoxin-induced animal model of perimenopause characterized by a prolonged estrogen-replete period of elevated FSH, we examined longitudinal changes in bone mineral density (BMD) and their association with FSH. Additionally, serum inhibin levels were assessed to determine whether elevated FSH occurred secondary to decreased ovarian inhibin production and, if so, whether inhibins also correlated with BMD. BMD of the distal femur was assessed using dual-energy X-ray absorptiometry (DXA) over 19 months in Sprague-Dawley rats treated at 1 month with vehicle or 4-vinylcyclohexene diepoxide (VCD, 80 or 160 mg/kg daily). Serum FSH, inhibins A and B, and 17-ß estradiol (E(2)) were assayed and estrus cyclicity was assessed. VCD caused dose-dependent increases in FSH that exceeded values occurring with natural senescence, hastening the onset and prolonging the duration of persistent estrus, an acyclic but E(2)-replete period. VCD decreased serum inhibins A and B, which were inversely correlated with FSH (r(2) = 0.30 and 0.12, respectively). In VCD rats, significant decreases in BMD (5-13%) occurred during periods of increased FSH and decreased inhibins, while BMD was unchanged in controls. In skeletally mature rats, FSH (r(2) = 0.13) and inhibin A (r(2) = 0.15) correlated with BMD, while inhibin B and E(2) did not. Thus, for the first time, both the hormonal milieu of perimenopause and the association of dynamic perimenopausal changes in FSH and inhibin A with decreased BMD have been reproduced in an animal model.
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Affiliation(s)
- A L Lukefahr
- Department of Medicine, The University of Arizona, 1656 E. Mabel Street, PO Box 24-5218, Tucson, AZ 85724, USA
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Abstract
During the last two decades a large number of genetically modified mouse lines with altered gonadotropin action have been generated. These mouse lines fall into three categories: the lack-of-function mice, gain-of-function mice, and the mice generated by breeding the abovementioned lines with other disease model lines. The mouse strains lacking gonadotropin action have elucidated the necessity of the pituitary hormones in pubertal development and function of gonads, and revealed the processes from the original genetic defect to the pathological phenotype such as hypo- or hypergonadotropic hypogonadism. Conversely, the strains of the second group depict consequences of chronic gonadotropin action. The lines vary from those expressing constitutively active receptors and those secreting follicle-stimulating hormone (FSH) with slowly increasing amounts to those producing human choriogonadotropin (hCG), amount of which corresponds to 2000-fold luteinizing hormone (LH)/hCG biological activity. Accordingly, the phenotypes diverge from mild anomalies and enhanced fertility to disrupted gametogenesis, but eventually chronic, enhanced and non-pulsatile action of both FSH and LH leads to female and male infertility and/or hyper- and neoplasias in most of the gonadotropin gain-of-function mice. Elevated gonadotropin levels also alter the function of several extra-gonadal tissues either directly or indirectly via increased sex steroid production. These effects include promotion of tumorigenesis in tissues such as the pituitary, mammary and adrenal glands. Finally, the crossbreedings of the current mouse strains with other disease models are likely to uncover the contribution of gonadotropins in novel biological systems, as exemplified by the recent crossbreed of LHCG receptor deficient mice with Alzheimer disease mice.
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Affiliation(s)
- Hellevi Peltoketo
- Institute of Reproductive and Developmental Biology, Imperial College London, DuCane Road, London, W12 0NN, UK.
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Rouach V, Katzburg S, Koch Y, Stern N, Somjen D. Bone loss in ovariectomized rats: Dominant role for estrogen but apparently not for FSH. J Cell Biochem 2011; 112:128-37. [DOI: 10.1002/jcb.22908] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kumar KK, Tung S, Iqbal J. Bone loss in anorexia nervosa: leptin, serotonin, and the sympathetic nervous system. Ann N Y Acad Sci 2010; 1211:51-65. [PMID: 21062295 DOI: 10.1111/j.1749-6632.2010.05810.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Anorexia nervosa (AN), a disorder characterized by the refusal to sustain a healthy weight, has the highest mortality of any psychiatric disorder. This review presents a model of AN that ties together advances in our understanding of how leptin, serotonin, and hypogonadism are brought about in AN and how they influence bone mass. Serotonin (5-hydroxytryptamine) is a key regulator of satiety and mood. The primary disturbance in AN results from alterations in serotonin signaling. AN patients suffer from serotonergic hyperactivity of Htr1a-dependent pathways that causes dysphoric mood and promotes restrictive behavior. By limiting carbohydrate ingestion, anorexics decrease their serotonin levels. Reduced serotonergic signaling in turn suppresses appetite through Htr1a/2b, decreases dysphoric mood through Htr1a/2a, and activates the sympathetic nervous system (SNS) through Htr2c receptors in the ventromedial hypothalamus. Activation of the SNS decreases bone mass through β2-adrenergic signaling in osteoblasts. Additional topics reviewed here include osteoblastic feedback of metabolism in anorexia, mechanisms whereby dietary changes exacerbate bone loss, the role of caloric restriction and Sirt1 in bone metabolism, hypothalamic hypogonadism's effects on bone mass, and potential treatments.
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Affiliation(s)
- Kevin K Kumar
- Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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