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1.
J Couns Psychol ; 67(6): 653-668, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32212761

RESUMO

In this qualitative study, we explored the role that social activism and #MeToo and other large scale antiviolence activist movements may play in sexual assault survivors' healing process and how they navigate and make sense of their sexual assault experience. We interviewed 16 adult sexual assault survivors (13 women, 2 genderqueer/nonconforming individuals, and 1 identifying as a man and genderqueer) who were engaged in anti-sexual assault activism and analyzed their data using thematic analysis. Participants were predominately White and highly educated. We found that activism helped participants find their voice and regain their power. They described a process of moving from silence and shame around their sexual assault to freedom and empowerment. Their involvement in activism and/or connection to larger scale antiviolence activist movements (a) helped increase their understanding of themselves and their sexual assault experience, (b) served as a useful coping mechanism, (c) improved their self-confidence and relationships, (d) allowed them to stand up and speak out against attitudes and behaviors that foster rape culture, (e) provided support, validation, and connection to others, and (f) provided a source of meaning and fulfillment in their lives. Helping other survivors through their activist work also contributed to participants' healing process. Participants also described challenges associated with anti-sexual assault activism and #MeToo and related movements. These included being triggered, being inundated with media coverage and public narratives about sexual assault, burning out, and feeling disillusioned and frustrated. Finally, participants noted the importance of mainstream movements in increasing awareness. (PsycInfo Database Record (c) 2020 APA, all rights reserved).


Assuntos
Vítimas de Crime/psicologia , Dor/psicologia , Ativismo Político , Resiliência Psicológica , Delitos Sexuais/psicologia , Sobreviventes/psicologia , Direitos da Mulher , Adaptação Psicológica , Adulto , Idoso , Atitude , Feminino , Humanos , Masculino , Meios de Comunicação de Massa , Pessoa de Meia-Idade , Pesquisa Qualitativa , Estupro/psicologia , Autoimagem , Vergonha , Adulto Jovem
2.
PLoS One ; 6(6): e21402, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21731732

RESUMO

Androgens are important regulators of bone mass but the relative importance of testosterone (T) versus dihydrotestosterone (DHT) for the activation of the androgen receptor (AR) in bone is unknown. 5α-reductase is responsible for the irreversible conversion of T to the more potent AR activator DHT. There are two well established isoenzymes of 5α-reductase (type 1 and type 2), encoded by separate genes (Srd5a1 and Srd5a2). 5α-reductase type 2 is predominantly expressed in male reproductive tissues whereas 5α-reductase type 1 is highly expressed in liver and moderately expressed in several other tissues including bone. The aim of the present study was to investigate the role of 5α-reductase type 1 for bone mass using Srd5a1⁻/⁻ mice. Four-month-old male Srd5a1⁻/⁻ mice had reduced trabecular bone mineral density (-36%, p<0.05) and cortical bone mineral content (-15%, p<0.05) but unchanged serum androgen levels compared with wild type (WT) mice. The cortical bone dimensions were reduced in the male Srd5a1⁻/⁻ mice as a result of a reduced cortical periosteal circumference compared with WT mice. T treatment increased the cortical periosteal circumference (p<0.05) in orchidectomized WT mice but not in orchidectomized Srd5a1⁻/⁻ mice. Male Srd5a1⁻/⁻ mice demonstrated a reduced forelimb muscle grip strength compared with WT mice (p<0.05). Female Srd5a1⁻/⁻ mice had slightly increased cortical bone mass associated with elevated circulating levels of androgens. In conclusion, 5α-reductase type 1 inactivated male mice have reduced bone mass and forelimb muscle grip strength and we propose that these effects are due to lack of 5α-reductase type 1 expression in bone and muscle. In contrast, the increased cortical bone mass in female Srd5a1⁻/⁻ mice, is an indirect effect mediated by elevated circulating androgen levels.


Assuntos
3-Oxo-5-alfa-Esteroide 4-Desidrogenase/deficiência , Osso e Ossos/patologia , Osso e Ossos/fisiopatologia , Proteínas de Membrana/deficiência , Força Muscular/fisiologia , 3-Oxo-5-alfa-Esteroide 4-Desidrogenase/genética , 3-Oxo-5-alfa-Esteroide 4-Desidrogenase/metabolismo , Androgênios/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Peso Corporal/fisiologia , Densidade Óssea/efeitos dos fármacos , Densidade Óssea/fisiologia , Ativação Enzimática/efeitos dos fármacos , Feminino , Membro Anterior/efeitos dos fármacos , Membro Anterior/fisiologia , Perfilação da Expressão Gênica , Força da Mão/fisiologia , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Força Muscular/efeitos dos fármacos , Orquiectomia , Tamanho do Órgão/efeitos dos fármacos , Ovário/efeitos dos fármacos , Ovário/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores da Prolactina/sangue , Receptores da Prolactina/genética , Testosterona/farmacologia , Vísceras/efeitos dos fármacos , Vísceras/metabolismo
3.
J Mol Endocrinol ; 45(1): 45-57, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20435684

RESUMO

Testosterone is a major regulator of muscle mass. Little is known whether this is due to a direct stimulation of the androgen receptor (AR) or mediated by aromatization of testosterone to estradiol (E(2)), the ligand for the estrogen receptors (ERs), in peripheral tissues. In this study, we differentiated between the effects mediated by AR and ER by treating orchidectomized (orx) male mice for 5 weeks with E(2) or the non-aromatizable androgen dihydrotestosterone (DHT). Both E(2) and DHT increased muscle weight and lean mass, although the effect was less marked after E(2) treatment. Studies of underlying mechanisms were performed using gene transcript profiling (microarray and real-time PCR) in skeletal muscle, and they demonstrated that E(2) regulated 51 genes and DHT regulated 187 genes, with 13 genes (=25% of E(2)-regulated genes) being regulated by both treatments. Both E(2) and DHT altered the expression of Fbxo32, a gene involved in skeletal muscle atrophy, affected the IGF1 system, and regulated genes involved in angiogenesis and the glutathione metabolic process. Only E(2) affected genes that regulate intermediary glucose and lipid metabolism, and only DHT increased the expression of genes involved in synaptic transmission and heme and polyamine biosynthesis. In summary, ER activation by E(2) treatment maintains skeletal muscle mass after orx. This effect is less marked than that of AR activation by DHT treatment, which completely prevented the effect of orx on muscle mass and was partly, but not fully, mediated via alternative pathways.


Assuntos
Músculo Esquelético , Orquiectomia , Receptores Androgênicos/metabolismo , Receptores de Estrogênio/metabolismo , Transdução de Sinais/fisiologia , Androgênios/metabolismo , Animais , Di-Hidrotestosterona/farmacologia , Estradiol/farmacologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Análise em Microsséries , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/fisiologia
4.
J Bone Miner Res ; 24(7): 1263-70, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19257817

RESUMO

The stimulatory effects of testosterone (T) on bone can either be through a direct activation of the androgen receptor (AR) or mediated through aromatization of T to estradiol (E2), followed by activation of estrogen receptors (ERs) in bone. Aromatase expression in osteoblasts and reproductive tissues is dependent on different promoters, which are differentially regulated. To study the effect of elevated local aromatization of T to E2 in bone, we developed a transgenic mouse model (Coll-1alpha1-Arom) that overexpresses the human aromatase gene under the control of the osteoblast specific rat type I alpha I procollagen promoter. The Coll-1alpha1-Arom mice expressed human aromatase mRNA specifically in bone and had unaffected serum E2 and T levels. Male Coll-1alpha1-Arom mice had clearly increased total body BMD, trabecular BMD, cortical BMD, and cortical thickness associated with elevated osteoprotegerin mRNA levels and reduced number of osteoclasts (p < 0.01). Treatment of ovariectomized mice with T increased cortical and trabecular thickness in the Coll-1alpha1-Arom mice (p < 0.001) but not in the wildtype mice. In conclusion, elevated aromatase expression specifically in osteoblasts results in stimulatory estrogenic effects in bone without increasing serum E2 levels. Because osteoblast-specific aromatase expression results in an increased ER to AR activation ratio in bone, we propose that activation of ERs results in a more pronounced increase in bone mass than what is seen after activation of the AR. Development of osteoblast-specific inducers of aromatase expression might identify substances with stimulatory effects on bone without systemic adverse effects.


Assuntos
Aromatase/biossíntese , Densidade Óssea , Estradiol/metabolismo , Osteoblastos/enzimologia , Testosterona/metabolismo , Animais , Aromatase/genética , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Ratos , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo
5.
J Clin Endocrinol Metab ; 92(12): 4878-82, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17698910

RESUMO

CONTEXT: Previous in vitro studies have demonstrated that the UDP glucuronosyltransferase (UGT)2B15 and UGT2B17 glucuronidate androgens and their metabolites. OBJECTIVE: Our objective was to determine in vivo whether the UGT2B15 D85Y and the UGT2B17 deletion polymorphisms predict androgen glucuronidation and body composition. PARTICIPANTS: Two population-based cohorts including young adult (n = 1068; age = 18.9 yr) and elderly (n = 1001; age = 75.3 yr) men were included in the study. MAIN OUTCOME MEASURES: Serum and urine levels of testosterone (T) and dihydrotestosterone (DHT) were measured by gas chromatography-mass spectrometry, and serum levels of the major glucuronidated androgen metabolites androstane-3alpha,17beta-diol(androstanediol)-3-glucuronide, androstanediol-17-glucuronide, and androsterone-glucuronide were measured by liquid chromatography-tandem mass spectrometry. Body composition was measured by dual-energy x-ray absorptiometry. RESULTS: Both the UGT2B15 D85Y and the UGT2B17 deletion polymorphisms were associated with serum levels of androstanediol-17-glucuronide (P < 0.001) but not with levels of androstanediol-3-glucuronide or androsterone-glucuronide in both cohorts. Glucuronidation of T and DHT was associated with the UGT2B17 deletion but not with the UGT2B15 D85Y polymorphism, suggested by strong associations between the deletion polymorphism and urine levels of these two hormones. Both polymorphisms were associated with several different measures of fat mass (P < 0.01). The UGT2B17 deletion polymorphism was associated with insulin sensitivity (P < 0.05) as indicated by the homeostasis model assessment index. CONCLUSIONS: The UGT2B15 D85Y and the UGT2B17 deletion polymorphisms are both predictors of the glucuronidation pattern of androgens/androgen metabolites. Our findings indicate that UGT2B17 is involved in 17-glucuronidation of mainly T but also of DHT and androstanediol and that UGT2B15 is involved in the 17-glucuronidation of androstanediol. Furthermore, these two polymorphisms are predictors of fat mass in men.


Assuntos
Adiposidade/genética , Androgênios/metabolismo , Glucuronosiltransferase/genética , Absorciometria de Fóton , Adiposidade/fisiologia , Adolescente , Adulto , Idoso , Envelhecimento/fisiologia , Glicemia/metabolismo , Composição Corporal/genética , Composição Corporal/fisiologia , Deleção de Genes , Glucuronídeos/metabolismo , Hormônios Esteroides Gonadais/sangue , Hormônios Esteroides Gonadais/urina , Humanos , Insulina/sangue , Insulina/urina , Resistência à Insulina , Masculino , Polimorfismo Genético/genética , Globulina de Ligação a Hormônio Sexual/metabolismo , Globulina de Ligação a Hormônio Sexual/urina
6.
J Clin Endocrinol Metab ; 92(11): 4130-7, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17711928

RESUMO

CONTEXT: Androgens are associated with metabolic risk factors in men. However, the independent impact of androgens and androgen metabolites on metabolic risk factors in men is unclear. OBJECTIVE: Our objective was to determine the predictive value of serum levels of androgens and glucuronidated androgen metabolites for metabolic risk factors. DESIGN AND STUDY SUBJECTS: We conducted a population-based study of two Swedish cohorts (1,068 young adult and 1,001 elderly men). MAIN OUTCOME MEASURES: We measured correlation of serum dihydrotestosterone (DHT), testosterone (T), and glucuronidated androgen metabolites with fat mass, fat distribution, serum lipids, and insulin resistance. RESULTS: Both DHT and T were negatively associated with different measures of fat mass in both cohorts (P < 0.001). Further statistical analysis indicated that DHT, but not T, was independently negatively associated with different measures of fat mass and insulin resistance (P < 0.001). The glucuronidated androgen metabolite androstane-3alpha,17beta-diol-17glucuronide (17G) was independently positively associated with fat mass (P < 0.001). Most importantly, the 17G to DHT ratio was strongly correlated, not only with fat mass but also with central fat distribution, intrahepatic fat, disturbed lipid profile, insulin resistance, and diabetes, explaining a substantial part of the total variance in total body fat (12% in young adult men, 15% in elderly men), the homeostasis model assessment index (10%), and high-density lipoprotein cholesterol (7%). CONCLUSION: Our findings demonstrate that 17-glucuronidation of the DHT metabolite androstane-3alpha,17beta-diol is strongly associated with several metabolic risk factors in men. Future longitudinal studies are required to determine the possible impact of the 17G to DHT ratio as a metabolic risk factor in men.


Assuntos
Androgênios/sangue , Abdome/anatomia & histologia , Absorciometria de Fóton , Adulto , Idoso , Envelhecimento/fisiologia , Braço/anatomia & histologia , Glicemia/metabolismo , Índice de Massa Corporal , Peso Corporal , Estudos de Coortes , Glucuronatos/sangue , Hormônios Esteroides Gonadais/sangue , Humanos , Insulina/sangue , Perna (Membro)/anatomia & histologia , Leptina/sangue , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Suécia , Tomografia Computadorizada por Raios X
7.
J Clin Endocrinol Metab ; 92(9): 3697-704, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17579197

RESUMO

CONTEXT: Sex steroids are involved in the regulation of pubertal cortical bone expansion in males. In vitro studies have indicated that the enzyme uridine diphosphate glucuronosyltransferase (UGT) 2B7 has the capacity to glucuronidate sex steroids and their metabolites. OBJECTIVE: Our objective was to determine the impact of the H(268)Y polymorphism in the UGT2B7 gene on interindividual variation of serum levels of sex steroids and cortical bone dimensions. PARTICIPANTS: The population-based cohort Gothenburg Osteoporosis and Obesity Determinants study consists of 1068 young adult Swedish men (age 18.9 yr). MAIN OUTCOME MEASURES: Serum levels of sex steroids and the three major glucuronidated androgen metabolites, androstane-3alpha,17beta-diol-17glucuronide, androstane-3alpha,17beta-diol-3glucuronide, and androsterone-glucuronide, were analyzed. Cortical and trabecular volumetric bone mineral density and cortical bone size were measured by peripheral quantitative computer tomography. RESULTS: Serum levels of testosterone (YY 9% over HH; P < 0.01), dihydrotestosterone (YY 10% over HH; P < 0.01), and estradiol (YY 8% over HH; P < 0.01) were associated with the UGT2B7 H(268)Y polymorphism. The polymorphism was associated with androstane-3alpha,17beta-diol-17glucuronide and androstane-3alpha,17beta-diol-3glucuronide (P < 0.01), but not with androsterone-glucuronide serum levels. In addition, the UGT2B7 H(268)Y polymorphism was an independent predictor of cortical bone size, reflected by periosteal circumference and cortical moment of inertia (P < 0.01), in both the weight-bearing tibia and nonweight-bearing radius. CONCLUSIONS: The UGT2B7 H(268)Y polymorphism is independently associated with cortical bone size and serum sex steroid levels in young adult men. Subjects homozygous for the Y allele had higher serum testosterone and larger cortical bone size than subjects homozygous for the H allele. However, the underlying mechanism behind these associations is unknown and has to be studied further.


Assuntos
Osso e Ossos/anatomia & histologia , Glucuronosiltransferase/genética , Hormônios Esteroides Gonadais/sangue , Polimorfismo de Nucleotídeo Único , Adolescente , Adulto , Glucuronosiltransferase/metabolismo , Histidina/genética , Humanos , Masculino , Modelos Biológicos , Tamanho do Órgão/genética , Tirosina/genética
8.
J Bone Miner Res ; 22(2): 220-7, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17059374

RESUMO

UNLABELLED: Androgens are important regulators of bone and prostate health in elderly men. The role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in men is unclear. We show that specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. INTRODUCTION: Androgens are important regulators of bone and prostate health in elderly men. Local synthesis and degradation of androgens are likely to be important parameters of biological action of androgens in androgen-responsive tissues. The aim of this study was to determine the role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in elderly men. MATERIALS AND METHODS: A subsample of the population-based Swedish part of the MrOS study (n = 631, average age = 75.9 years) was investigated. Bone parameters were measured using DXA. Serum levels of total testosterone (T) and dihydrotestosterone (DHT) were measured by gas chromatography/mass spectroscopy (GC-MS); androstane-3alpha,17beta-diol-3glucuronide (3G) and androstane-3alpha,17beta-diol-17glucuronide (17G) were measured by liquid chromatography/mass spectroscopy. Prostate volume (n = 159) was measured by transrectal ultrasound. RESULTS: The general pattern is that two of the glucuronidated androgen metabolites, namely 17G and 3G, are stronger positive predictors of BMD than the bioactive androgens (T and DHT). In addition, 17G is a clear positive predictor of prostate volume, explaining 4.5% of the variance in prostate volume, whereas the bioactive androgens do not display any association with prostate volume. CONCLUSIONS: Serum levels of specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. Future studies should determine if the glucuronidated androgen metabolites also reflect other biological correlates of androgenic activity, including prostate cancer, and if low levels might be a marker of general androgen deficiency in men.


Assuntos
Androgênios/sangue , Densidade Óssea , Glucuronídeos/sangue , Próstata/anatomia & histologia , Absorciometria de Fóton , Idoso , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Masculino , Radioimunoensaio
9.
Obesity (Silver Spring) ; 14(4): 662-72, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16741268

RESUMO

OBJECTIVE: To determine the role of androgen receptor (AR) activation for adipose tissue metabolism. Sex steroids are important regulators of adipose tissue metabolism in men. Androgens may regulate the adipose tissue metabolism in men either directly by stimulation of the AR or indirectly by aromatization of androgens into estrogens and, thereafter, by stimulation of the estrogen receptors. Previous studies have shown that estrogen receptor alpha stimulation results in reduced fat mass in men. RESEARCH METHODS AND PROCEDURES: Orchidectomized mice were treated with the non-aromatizable androgen 5alpha-dihydrotestosterone (DHT), 17beta-estradiol, or vehicle. Vo(2), Vco(2), resting metabolic rate, locomotor activity, and food consumption were measured. Furthermore, changes in hepatic gene expression were analyzed. RESULTS: DHT treatment resulted in obesity, associated with reduced energy expenditure and fat oxidation. In contrast, DHT did not affect food consumption or locomotor activity. Furthermore, DHT treatment resulted in increased high-density lipoprotein-cholesterol and triglyceride levels associated with markedly decreased 7alpha-hydroxylase gene expression, indicating decreased bile acid production. DISCUSSION: We showed that AR activation results in obesity and altered lipid metabolism in orchidectomized mice. One may speculate that AR antagonists might be useful in the treatment of obesity in men.


Assuntos
Di-Hidrotestosterona/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Obesidade/induzido quimicamente , Orquiectomia/efeitos adversos , Receptores Androgênicos/fisiologia , Adiposidade/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Calorimetria Indireta , Colesterol/sangue , Colesterol/metabolismo , HDL-Colesterol/sangue , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Triglicerídeos/sangue , Triglicerídeos/metabolismo
10.
Endocrinology ; 147(7): 3613-22, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16614077

RESUMO

In the present study, dexamethasone treatment of neonatal mouse calvarial bones increased mRNA expression of tartrate-resistant acid phosphatase, calcitonin receptor (CTR), cathepsin K, carbonic anhydrase II, osteoprotegerin (OPG), and receptor activator of nuclear factor-kappaB (RANK) as well as mRNA and protein expression of RANK ligand (RANKL). The increase in OPG mRNA noted with dexamethasone was in contrast to 1,25(OH)(2)-vitamin D3 (D3) treatment, which decreased OPG expression. Stimulation of (45)Ca release by dexamethasone and hydrocortisone in calvariae was blocked by OPG. Stimulation of RANKL, RANK, OPG, and CTR mRNA expression by dexamethasone in calvariae was blocked by the glucocorticoid receptor antagonist RU 38,486. Greater than additive potentiations of CTR mRNA and RANKL mRNA and protein were observed when D3 and dexamethasone were combined. Vitamin D receptor mRNA was increased by dexamethasone and D3, whereas glucocorticoid receptor (GR) mRNA was decreased by dexamethasone and unaffected by D3. No synergistic interaction between dexamethasone and D3 on either vitamin D receptor or GR mRNA expression was noted. The data demonstrate that dexamethasone-induced bone resorption in calvarial bones is associated with increased differentiation of osteoclasts and regulation of the RANKL-RANK-OPG system. The increase in OPG expression and the decrease of GR expression noted with dexamethasone offer an explanation for why bone breakdown in mouse calvariae treated with glucocorticoids is less than that caused by resorptive agents like D3. The synergistic stimulation of RANKL by dexamethasone and D3 offers an explanation of how glucocorticoids and D3 interact to potentiate bone resorption.


Assuntos
Proteínas de Transporte/metabolismo , Glucocorticoides/metabolismo , Glicoproteínas/metabolismo , Glicoproteínas de Membrana/metabolismo , NF-kappa B/metabolismo , Osteoclastos/citologia , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Crânio/metabolismo , Animais , Reabsorção Óssea , Diferenciação Celular , Dexametasona/metabolismo , Dexametasona/farmacologia , Ligantes , Camundongos , Mifepristona/farmacologia , Osteoprotegerina , Ligante RANK , Receptor Ativador de Fator Nuclear kappa-B , Receptores de Glucocorticoides/metabolismo
11.
J Bone Miner Res ; 21(2): 332-9, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16418790

RESUMO

UNLABELLED: The association between aromatase gene polymorphisms, bone parameters, and sex steroid levels was studied in 1068 men (18.9 +/- 0.6 years of age). Several aromatase gene polymorphisms were found to be associated with serum testosterone levels and cortical bone size but not with trabecular volumetric BMD. INTRODUCTION: Both testosterone and estrogens are important for the male skeleton. Aromatase, the product of the CYP19 gene, is the key enzyme in the conversion of testosterone to estradiol. A functional aromatase enzyme has been shown to be crucial for the normal development of the male skeleton. The role of genetic polymorphisms in the aromatase gene for trabecular volumetric BMD (vBMD) and cortical bone size has not previously been studied in men. MATERIALS AND METHODS: The Gothenburg Osteoporosis and Obesity Determinants (GOOD) study consists of 1068 men (18.9 +/- 0.6 years of age). The TTTA repeat polymorphism (TTTAn) and three single nucleotide polymorphisms (SNPs), including the Val80 SNP, in the CYP19 gene, were analyzed. Serum levels of testosterone and estradiol were measured. Areal BMD (aBMD) was measured by DXA, whereas cortical and trabecular vBMD and cortical bone size were measured by pQCT. RESULTS: The TTTAn and the Val80 genotypes were independent predictors of aBMD of the radius, lumbar spine, total body, and cortical bone size (cortical cross-sectional area and thickness) of both the radius and tibia. In contrast, trabecular vBMD was not associated with CYP19 polymorphisms. Homozygosity for the long allele (>9 repeats) of the TTTAn and for the G allele of the Val80 SNP was associated with the highest aBMD and testosterone levels as well as with the greatest cortical bone size. Regression analyses indicated that the association with aBMD was mediated through affected cortical bone size. CONCLUSIONS: We showed, in a large well-characterized cohort of men at the age of peak bone mass, that several common aromatase polymorphisms are associated with cortical bone size but not with trabecular vBMD. One may speculate that affected CYP19 activity, resulting in altered testosterone levels during pubertal development, might contribute to the association between CYP19 polymorphisms and cortical bone size.


Assuntos
Aromatase/genética , Densidade Óssea/genética , Desenvolvimento Ósseo/genética , Osso e Ossos/anatomia & histologia , Polimorfismo de Nucleotídeo Único , Testosterona/sangue , Absorciometria de Fóton , Adolescente , Adulto , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/metabolismo , Estudos de Coortes , Estradiol/sangue , Humanos , Masculino , Prognóstico
12.
J Endocrinol ; 187(2): 303-9, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16293778

RESUMO

It is generally believed that estrogens exert their bone sparing effects directly on the cells within the bone compartment. The aim of the present study was to investigate if central mechanisms might be involved in the bone sparing effect of estrogens. The dose-response of central (i.c.v) 17beta-estradiol (E2) administration was compared with that of peripheral (s.c.) administration in ovariectomized (ovx) mice. The dose-response curves for central and peripheral E2 administration did not differ for any of the studied estrogen-responsive tissues, indicating that these effects were mainly peripheral. In addition, ovx mice were treated with E2 and/or the peripheral estrogen receptor antagonist ICI 182,780. ICI 182,780 attenuated most of the estrogenic response regarding uterus weight, retroperitoneal fat weight, cortical BMC and trabecular bone mineral content (P<0.05). These findings support the notion that the primary target tissue that mediates the effect of E2 on bone is peripheral and not central.


Assuntos
Osso e Ossos/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Estradiol/administração & dosagem , Osteoporose Pós-Menopausa/metabolismo , Animais , Densidade Óssea , Relação Dose-Resposta a Droga , Implantes de Medicamento , Estradiol/análogos & derivados , Estradiol/farmacologia , Antagonistas de Estrogênios/farmacologia , Feminino , Fêmur/efeitos dos fármacos , Fêmur/fisiopatologia , Fulvestranto , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Modelos Animais , Osteoporose Pós-Menopausa/fisiopatologia , Ovariectomia , Tíbia/efeitos dos fármacos , Tíbia/fisiopatologia , Tomografia Computadorizada por Raios X
13.
J Bone Miner Res ; 20(8): 1334-41, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16007330

RESUMO

UNLABELLED: In this study, we evaluated the predictive roles of sex steroids for skeletal parameters in young men (n = 1068) at the age of peak bone mass. Serum free estradiol was a negative predictor, whereas free testosterone and SHBG were positive predictors of cortical bone size. INTRODUCTION: Previous studies have shown that free estradiol in serum is an independent predictor of areal BMD (aBMD) in elderly men. The aim of this study was to determine whether sex steroids are predictors of volumetric BMD (vBMD) and/or size of the trabecular and cortical bone compartments in young men at the age of peak bone mass. MATERIALS AND METHODS: The Gothenburg Osteoporosis and Obesity Determinants (GOOD) study consists of 1068 men, 18.9 +/- 0.6 years of age. Serum levels of testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured, and free levels of testosterone and estradiol were calculated. The size of the cortical bone and the cortical and trabecular vBMDs were measured by pQCT. RESULTS: Regression models including age, height, weight, free estradiol, and free testosterone showed that free estradiol was an independent negative predictor of cortical cross-sectional area (tibia beta = -0.111, p < 0.001; radius beta = -0.125, p < 0.001), periosteal circumference, and endosteal circumference, whereas it was a positive independent predictor of cortical vBMD (tibia beta = 0.100, p < 0.003; radius beta = 0.115, p = 0.001) in both the tibia and radius. Free testosterone was an independent positive predictor of cortical cross-sectional area (tibia beta = 0.071, p = 0.013; radius beta = 0.064, p = 0.039), periosteal circumference, and endosteal circumference in both the tibia and radius. Neither cortical nor trabecular vBMD was associated with free testosterone. SHBG was an independent positive predictor of parameters reflecting the size of the cortical bone, including cross-sectional area (beta = 0.078, p = 0.009), periosteal circumference, and endosteal circumference. CONCLUSIONS: Free estradiol is a negative, whereas free testosterone is a positive, predictor of cortical bone size in young men at the age of peak bone mass. These findings support the notion that estrogens reduce, whereas androgens increase, cortical bone size, resulting in the well-known sexual dimorphism of cortical bone geometry.


Assuntos
Desenvolvimento Ósseo , Osso e Ossos/diagnóstico por imagem , Estradiol/sangue , Testosterona/sangue , Absorciometria de Fóton , Adolescente , Adulto , Fatores Etários , Biomarcadores/sangue , Estatura , Peso Corporal , Densidade Óssea/fisiologia , Humanos , Fator de Crescimento Insulin-Like I/análise , Masculino , Suécia , Tomografia Computadorizada por Raios X
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