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‣ Social modulation of androgen levels in male teleost fish

Oliveira, R. F.; Hirschenhauser, K.; Carneiro, L. A.; Canario, Adelino V. M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /05/2002 Português
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Androgens are classically thought of as the sex steroids controlling male reproduction. However, in recent years evidence has accumulated showing that androgens can also be affected by the interactions between conspecifics, suggesting reciprocal interactions between androgens and behaviour. These results have been interpreted as an adaptation for individuals to adjust their agonistic motivation and to cope with changes in their social environment. Thus, male–male interactions would stimulate the production of androgens, and the levels of androgens would be a function of the stability of its social environment [‘challenge hypothesis’, Gen. Comp. Endocrinol. 56 (1984) 417]. Here the available data on social modulation of androgen levels in male teleosts are reviewed and some predictions of the challenge hypothesis are addressed using teleosts as a study model. We investigate the causal link between social status, territoriality and elevated androgen levels and the available evidence suggests that the social environment indeed modulates the endocrine axis of teleosts. The association between higher androgen levels and social rank emerges mainly in periods of social instability. As reported in the avian literature, in teleosts the trade-off between androgens and parental care is indicated by the fact that during the parental phase breeding males decreased their androgen levels. A comparison of androgen responsiveness between teleost species with different mating and parenting systems also reveals that parenting explains the variation observed in androgen responsiveness to a higher degree than the mating strategy. Finally...

‣ Coordinate regulation of lipogenic gene expression by androgens: Evidence for a cascade mechanism involving sterol regulatory element binding proteins

Swinnen, Johannes V.; Ulrix, William; Heyns, Walter; Verhoeven, Guido
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 25/11/1997 Português
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To gain more insight into the molecular mechanisms by which androgens stimulate lipogenesis and induce a marked accumulation of neutral lipids in the human prostate cancer cell line LNCaP, we studied their impact on the expression of lipogenic enzymes. Northern blot analysis of the steady-state mRNA levels of seven different lipogenic enzymes revealed that androgens coordinately stimulate the expression of enzymes belonging to the two major lipogenic pathways: fatty acid synthesis and cholesterol synthesis. In view of the important role of the recently characterized sterol regulatory element binding proteins (SREBPs) in the coordinate induction of lipogenic genes, we examined whether the observed effects of androgens on lipogenic gene expression are mediated by these transcription factors. Our findings indicate that androgens stimulate the expression of SREBP transcripts and precursor proteins and enhance the nuclear content of the mature active form of the transcription factor. Moreover, by using the fatty acid synthase gene as an experimental paradigm we demonstrate that the presence of an SREBP-binding site is essential for its regulation by androgens. These data support the hypothesis that SREBPs are involved in the coordinate regulation of lipogenic gene expression by androgens and provide evidence for the existence of a cascade mechanism of androgen-regulated gene expression.

‣ Secretion of Unconjugated Androgens and Estrogens by the Normal and Abnormal Human Testis before and after Human Chorionic Gonadotropin

Weinstein, R. L.; Kelch, R. P.; Jenner, M. R.; Kaplan, S. L.; Grumbach, M. M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1974 Português
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The secretion of androgens and estrogens by normal and abnormal testes was compared by determining the concentrations of dehydroepiandrosterone (DHEA), androstenedione (Δ4A), testosterone (T), estrone (E1), and 17β-estradiol (E2) in peripheral and spermatic venous plasma samples from 14 normal men and 5 men with unilateral testicular atrophy. Four normal men and one patient with unilateral atrophy of the testis were given human chorionic gonadotropin (HCG) before surgery. Plasma estrogens were determined by radioimmunoassay; plasma androgens were measured by the double-isotope dilution derivative technique. Peripheral concentrations of these steroids before and after HCG were similar in both the normal men and the patients with unilateral testicular atrophy. In normal men, the mean ±SE spermatic venous concentrations were DHEA, 73.1±11.7 ng/ml; Δ4A, 30.7±7.9 ng/ml; T, 751±114 ng/ml; E1, 306±55 pg/ml; and E2, 1298±216 pg/ml. Three of four subjects with unilateral testicular atrophy had greatly diminished spermatic venous levels of androgens and estrogens. HCG treatment increased the testicular secretion of DHEA and T fivefold, Δ4A threefold, E1 sixfold, and E2 eightfold in normal men. In the single subject with an atrophic testis who received HCG...

‣ Androgen conversion in osteoarthritis and rheumatoid arthritis synoviocytes – androstenedione and testosterone inhibit estrogen formation and favor production of more potent 5α-reduced androgens

Schmidt, Martin; Weidler, Claudia; Naumann, Heidrun; Anders, Sven; Schölmerich, Jürgen; Straub, Rainer H
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
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In synovial cells of patients with osteoarthritis (OA) and rheumatoid arthritis (RA), conversion products of major anti-inflammatory androgens are as yet unknown but may be proinflammatory. Therefore, therapy with androgens in RA could be a problem. This study was carried out in order to compare conversion products of androgens in RA and OA synoviocytes. In 26 OA and 24 RA patients, androgen conversion in synovial cells was investigated using radiolabeled substrates and analysis by thin-layer chromatography and HPLC. Aromatase expression was studied by immunohistochemistry. Dehydroepiandrosterone (DHEA) was converted into androstenediol, androstenedione (ASD), 16αOH-DHEA, 7αOH-DHEA, testosterone, estrone (E1), estradiol (E2), estriol (E3), and 16αOH-testosterone (similar in OA and RA). Surprisingly, levels of E2, E3, and 16α-hydroxylated steroids were as high as levels of testosterone. In RA and OA, 5α-dihydrotestosterone increased conversion of DHEA into testosterone but not into estrogens. The second androgen, ASD, was converted into 5α-dihydro-ASD, testosterone, and negligible amounts of E1, E2, E3, or 16αOH-testosterone. 5α-dihydro-ASD levels were higher in RA than OA. The third androgen, testosterone, was converted into ASD...

‣ Male fetal germ cells are targets for androgens that physiologically inhibit their proliferation

Merlet, Jorge; Racine, Chrystèle; Moreau, Evelyne; Moreno, Stéphanie G.; Habert, René
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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In adulthood, the action of androgens on seminiferous tubules is essential for full quantitatively normal spermatogenesis and fertility. In contrast, their role in the fetal testis, and particularly in fetal germ cell development, remains largely unknown. Using testicular feminized (Tfm) mice, we investigated the effects of a lack of functional androgen receptor (AR) on fetal germ cells, also named gonocytes. We demonstrated that endogenous androgens/AR physiologically control normal gonocyte proliferation. We observed an increase in the number of gonocytes at 17.5 days postconception resulting from an increase in proliferative activity in Tfm mice. In a reciprocal manner, gonocyte proliferation is decreased by the addition of DHT in fetal testis organotypic culture. Furthermore, the AR coregulator Hsp90α (mRNA and protein) specifically expressed in gonocytes was down-regulated in Tfm mice at 15.5 days postconception. To investigate whether these effects could result from direct action of androgens on gonocytes, we collected pure gonocyte preparations and detected AR transcripts therein. We used an original model harboring a reporter gene that specifically reflects AR activity by androgens and clearly demonstrated the presence of a functional AR protein in fetal germ cells. These data provide in vivo and in vitro evidence of a new control of endogenous androgens on gonocytes identified as direct target cells for androgens. Finally...

‣ Adolescents and Androgens, Receptors and Rewards

Sato, Satoru M.; Schulz, Kalynn M.; Sisk, Cheryl L.; Wood, Ruth I.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Adolescence is associated with increases in pleasure-seeking behaviors, which, in turn, are shaped by the pubertal activation of the hypothalamo-pituitary-gonadal axis. In animal models of naturally rewarding behaviors, such as sex, testicular androgens contribute to the development and expression of the behavior in males. To effect behavioral maturation, the brain undergoes significant remodeling during adolescence, and many of the changes are likewise sensitive to androgens, presumably acting through androgen receptors (AR). Given the delicate interaction of gonadal hormones and brain development, it is no surprise that disruption of hormone levels during this sensitive period significantly alters adolescent and adult behaviors. In male hamsters, exposure to testosterone during adolescence is required for normal expression of adult sexual behavior. Males deprived of androgens during puberty display sustained deficits in mating. Conversely, androgens alone are not sufficient to induce mating in prepubertal males, even though brain AR are present before puberty. In this context, wide-spread use of anabolic-androgenic steroids (AAS) during adolescence is a significant concern. AAS abuse has the potential to alter both the timing and the levels of androgens in adolescent males. In hamsters...

‣ Androgens and the breast

Dimitrakakis, Constantine; Bondy, Carolyn
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
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Androgens have important physiological effects in women while at the same time they may be implicated in breast cancer pathologies. However, data on the effects of androgens on mammary epithelial proliferation and/or breast cancer incidence are not in full agreement. We performed a literature review evaluating current clinical, genetic and epidemiological data regarding the role of androgens in mammary growth and neoplasia. Epidemiological studies appear to have significant methodological limitations and thus provide inconclusive results. The study of molecular defects involving androgenic pathways in breast cancer is still in its infancy. Clinical and nonhuman primate studies suggest that androgens inhibit mammary epithelial proliferation and breast growth while conventional estrogen treatment suppresses endogenous androgens. Abundant clinical evidence suggests that androgens normally inhibit mammary epithelial proliferation and breast growth. Suppression of androgens using conventional estrogen treatment may thus enhance estrogenic breast stimulation and possibly breast cancer risk. Addition of testosterone to the usual hormone therapy regimen may diminish the estrogen/progestin increase in breast cancer risk but the impact of this combined use on mammary gland homeostasis still needs evaluation.

‣ Effects of Synthetic Androgens on Liver Function Using the Rabbit as a Model*†

Hild, Sheri Ann; Attardi, Barbara J.; Koduri, Sailaja; Till, Bruce A.; Reel, Jerry R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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The objective of this study was to determine if the rabbit was a suitable model to test new synthetic androgens for potential liver toxicity within a short dosing interval. Adult male rabbits were dosed orally daily on days 0–13 with 17α-methyltestosterone (MT), as a positive control, and testosterone (T), as a negative control, to validate this model. Synthetic androgens tested were: 7α-methyl-19-nortestosterone (MENT), dimethandrolone-undecanoate (DMAU), and 11β-methyl-19-nortestosterone-17β-dodecylcarbonate (11β-MNTDC). Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), and sorbitol dehydrogenase (SDH), as well as clearance of intravenous injected bromsulfonphthalein (BSP) from serum on days 0, 7 and 14, were determined. As expected, T (10 mg/kg/day) did not adversely affect BSP retention or serum liver enzymes. MT (10 mg/kg/day) increased BSP retention, and AST, ALT, GGT, and SDH levels indicating that this model could detect androgens known to be hepatotoxic. DMAU and MENT (10 mg/kg/day), increased BSP retention, and all 4 serum liver enzymes as well, but the effects were less than those observed with MT at the same dose. All parameters returned to baseline 2 weeks after cessation of dosing. 11β-MNTDC at 10 mg/kg/day did not have an effect on BSP retention or liver enzymes...

‣ Bioactive Androgens and Glucuronidated Androgen Metabolites are Associated with Subcutaneous and Ectopic Skeletal Muscle Adiposity among Older Black Men

Miljkovic, Iva; Cauley, Jane A; Dressen, Amy S; Gordon, Christopher L; Goodpaster, Bret H; Kuller, Lewis H; Bunker, Clareann H; Patrick, Alan L; Wheeler, Victor W; Orwoll, Eric S; Zmuda, Joseph M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Aging is associated with declining serum levels of androgenic hormones and with increased skeletal muscle fat infiltration, an emerging risk factor for type 2 diabetes mellitus (T2DM). Androgens regulate fat mass and glucose homeostasis, but the effect of androgenic hormones on skeletal muscle fat infiltration is largely unknown. Thus, the aim of the current study was to examine the association of serum androgens and their precursors and metabolites with skeletal muscle fat infiltration and T2DM in a black male population group at high risk of T2DM. Serum androgens, estrogens, and androgen precursors and metabolites were measured using mass spectrometry, and calf skeletal muscle fat distribution [subcutaneous and intermuscular fat; skeletal muscle density] were measured using quantitative computed tomography in 472 Afro-Caribbean men aged 65 and older. Bioactive androgens, testosterone, free testosterone and dihydrotestosterone, were associated with less skeletal muscle fat infiltration (r=−0.14 to −0.18, P<0.05) and increased skeletal muscle density (r=0.10 to 0.14, P<0.05), independent of total adiposity. Additionally, glucuronidated androgen metabolites were associated with less subcutaneous fat (r=−0.11 to −0.15, P<0.05). Multivariate logistic regression analysis identified an increased level of 3α-diol-3 glucuronide (OR=1.38...

‣ Androgens promote the acquisition of maturation competence in bovine oocytes

MAKITA, Miho; MIYANO, Takashi
Fonte: The Society for Reproduction and Development Publicador: The Society for Reproduction and Development
Tipo: Artigo de Revista Científica
Português
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Recent studies in mice suggest that androgens are important for normal follicle development. However, there have been few reports concerning the action of androgens in the growth of oocytes from large animals. The purpose of this study was to determine the roles of androgens in bovine oocyte growth in vitro. Oocyte-granulosa cell complexes (OGCs) collected from 0.4−0.7 mm early antral follicles were cultured for 14 days with 17β-estradiol (E2) and a non-aromatizable androgen, dihydrotestosterone (DHT). We also examined the ability of an androgen receptor (AR) inhibitor, hydroxyflutamide, to antagonize the effect of androgens on the oocytes. During growth culture, the OGC structures collapsed in the medium with DHT alone, while in the presence of E2, the OGC structures were maintained. In the medium with both androgens and E2, the mean diameter of oocytes was increased from 95 μm to around 120 μm, larger than those grown with E2 alone (115 μm). Also in the maturation culture, oocytes grown with androgens (A4 or DHT) and E2 showed higher percentages of metaphase II oocytes (63% or 69%, respectively) than those grown with E2 alone (32%). Moreover, these maturation rates were decreased by hydroxyflutamide in a dose-dependent manner. Immunostaining showed that ARs were expressed in oocytes and granulosa cells in early antral follicles...

‣ Immuno-oncology of human prostate cancer : phenotypical characterization and study of the tumor-derived, androgen-regulated immunosuppressive microenvironment

Gannon, Philippe
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
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Le cancer de la prostate est le cancer le plus fréquemment diagnostiqué chez les hommes canadiens et la troisième cause de décès relié au cancer. Lorsque diagnostiqué à un stade précoce de la maladie, le cancer de la prostate est traité de manière curative par chirurgie et radiothérapie. Par contre, les thérapies actuelles ne peuvent éradiquer la maladie lorsqu’elle progresse à des stades avancés. Ces thérapies, comme la chimiothérapie et l’hormonothérapie, demeurent donc palliatives. Il est primordial d’optimiser de nouvelles thérapies visant l’élimination des cellules cancéreuses chez les patients atteints des stades avancés de la maladie. Une de ces nouvelles options thérapeutiques est l’immunothérapie. L’immunothérapie du cancer a fait des progrès considérables durant les dernières années. Cependant, les avancements encourageants obtenus lors d’essais précliniques ne se sont pas encore traduits en des résultats cliniques significatifs. En ce qui concerne le cancer de la prostate, les résultats négligeables suivants des interventions immunothérapeutiques peuvent être causés par le fait que la plupart des études sur le microenvironnement immunologique furent effectuées chez des modèles animaux. De plus la majorité des études sur l’immunologie tumorale humaine furent effectuées chez des patients atteints d’autres cancers...

‣ Androgens and androgen receptor signalling in men.

Need, Eleanor Frances
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008 Português
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Androgens are critical for the development and maintenance of adult male characteristics such as muscle mass and sexual function. Consequently, the established decline with age of serum testosterone (T) in males has major health implications. While the androgen receptor (AR) is the major mediator of genomic androgen action and is required for the development of the male phenotype, reproductive organs and the maintenance of male secondary sexual characteristics, it is the entrance of androgens into the cell that mediates the activation of the AR and the subsequent modulation of expression of androgen regulated genes. Testosterone, biologically the most important androgen in male serum, circulates either free, loosely bound to albumin or tightly bound to sex hormone binding globulin (SHBG). Each of these forms of serum T have different abilities to enter cells, and which proportion of serum T is capable of entering cells and initiating the androgen signalling cascade, thereby leading to the activation of the AR has not been precisely defined. The AR amino terminal domain (NTD) is responsible for the majority of the ability of the AR to activate genes but the relative roles of the two activation functions in the AR NTD (activation functions 1 and 5; AF1 and 5) have not been precisely defined while the role of the AF2 surface which forms in the ligand binding domain upon agonist binding is responsible for interactions with key coregulators and also with the NTD in the amino-carboxyl (N/C) interaction. Our laboratory has recently identified a region within AF5 between amino acids 500-535 to which somatic mutations in castrate resistant prostate tumour samples collocate. Due to the lack of functional information on the AF5 region and the NTD in general...

‣ Androgens and polycystic ovary syndrome

Nisenblat, V.; Norman, R.
Fonte: Lippincott Williams & Wilkins, Ltd. Publicador: Lippincott Williams & Wilkins, Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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PURPOSE OF REVIEW: Polycystic ovary syndrome (PCOS) is a common complex endocrine genetic disorder, which involves overproduction of androgens, leading to heterogeneous range of symptoms and associated with increased metabolic and cardiovascular morbidity. This review focuses on androgen biosynthesis, use, metabolism in PCOS and clinical consequences of hyperandrogenism. RECENT FINDINGS: Controversial definition of the disorder and different phenotypic subgroups present a challenge for clinical and basic research. Further investigation of different phenotypes highlights the fact that PCOS probably represents a group of disorders with different etiologies. Prenatal androgen exposure and adolescent studies suggest early in life androgen excess as initiating factor of PCOS, but insufficient evidence available to confirm this hypothesis. Various intracellular signaling pathways implicated in PCOS steroidogenesis and in androgen action have been studied, however, PCOS pathogenesis remains obscure. Growing evidence links androgens with pathophysiology of PCOS and metabolic derangements. SUMMARY: Despite intensive investigation, etiology and underlying mechanisms of PCOS remain unclear, warranting further investigation. Better understanding of molecular and genetic basis might lead to invention of novel therapeutic approaches. Long-term interventional studies that lower androgen levels in women with hyperandrogenism might protect against metabolic and cardiovascular comorbidities are needed.; Vicki Nisenblat...

‣ Non steroidal anti-inflammatory drug use and levels of oestrogens and androgens in men

Gates, M.; Araujo, A.; Hall, S.; Wittert, G.; McKinlay, J.
Fonte: Blackwell Science Ltd Publicador: Blackwell Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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Objective:  Studies suggest that regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) may lower oestrogen levels in women. However, no large, population-based studies have assessed NSAID/hormone associations in men. Our objective was to examine the association between use of prescription and over-the-counter NSAIDs, and levels of oestrogens and androgens in men. Design:  The Boston Area Community Health Survey, an observational survey with initial data collection in 2002–2005. Patients:  A total of 1766 men who provided a blood sample and data on recent analgesic use. Measurements:  Adjusted geometric mean levels of androgens, oestrogens, SHBG, LH and FSH for each category of NSAID use and the per cent difference in hormone levels for users vs nonusers. Results:  There was no significant association between prescription/over-the-counter NSAID use and any hormone examined after adjustment for potential confounders. For example, geometric mean testosterone levels were 13·8, 13·6 and 14·2 nm in nonusers, prescription users and over-the-counter NSAID users, respectively; the corresponding levels for estradiol were 80·3, 70·4 and 79·9 pm. In stratified analyses, however, prescription NSAID use was associated with lower testosterone...

‣ Androgens, diabetes and prostate cancer

Grossmann, M.; Wittert, G.
Fonte: Soc Endocrinology Publicador: Soc Endocrinology
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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36.860405%
Metabolic disorders such as diabetes, obesity and the metabolic syndrome have been shown to modulate prostate cancer (PCa) risk and aggressiveness in population-based and experimental studies. While associations between these conditions are modest and complex, two consistent findings have emerged. First, there is observational evidence that obesity and associated insulin excess are linked to increased PCa aggressiveness and worse outcomes. Secondly and somewhat paradoxically, long-standing diabetes may be protective against PCa development. This apparent paradox may be due to the fact that long-standing diabetes is associated with insulin depletion and decreased IGF1 signalling. Men with obesity or diabetes have moderate reductions in their androgen levels. The interconnectedness of metabolic and androgen status complicates the dissection of the individual roles of these factors in PCa development and progression. Metabolic factors and androgens may promote prostate carcinogenesis via multiple mechanisms including inflammation, adipokine action, fatty acid metabolism and IGF signalling. Moreover, androgen deprivation, given to men with PCa, has adverse metabolic consequences that need to be taken into account when estimating the risk benefit ratio of this therapy. In this review...

‣ Polycystic ovary syndrome and anti-Müllerian hormone: role of insulin resistance, androgens, obesity and gonadotrophins; Polycystic ovary syndrome and anti-Mullerian hormone: role of insulin resistance, androgens, obesity and gonadotrophins

Cassar, S.; Teede, H.J.; Moran, L.J.; Joham, A.E.; Harrison, C.L.; Strauss, B.J.; Stepto, N.K.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Objective: Polycystic ovary syndrome (PCOS) is a complex endocrine disorder associated with insulin resistance, hyperandrogenism, obesity, altered gonadotrophin release and anovulatory infertility. Anti-Müllerian hormone (AMH) has been proposed as a marker of ovarian function and fertility. Across a cohort of lean and overweight women with and without PCOS, we investigated the association of AMH with insulin resistance and body composition using gold standard measures. A secondary aim was to examine whether AMH was useful to determine PCOS status. Design: Cross-sectional study. Patients: A total of 22 lean and 21 overweight women with PCOS and 19 lean and 16 overweight non-PCOS healthy controls were recruited. PCOS was diagnosed based on the Rotterdam criteria. Measurements: Euglycaemic-hyperinsulinaemic clamp for assessing insulin resistance, dual energy X-ray absorptiometry and computed tomography for assessing adiposity, and blood sampling for the assessment of androgens, gonadotrophins and AMH. Results: Anti-Müllerian hormone levels were increased in women with PCOS (P <0·001) regardless of adiposity, with this increase associated with testosterone (P <0·001) rather than insulin resistance (P = 0·79), adiposity (P = 0·98) or gonadotrophins. In assessing the ability of AMH to predict PCOS...

‣ Effects of exposures to the plasticiser, di-n-butyl phthalate and the pharmaceutical, flutamide on the biomarkers of reproduction in Australian freshwater fish species, Murray rainbowfish (Melanotaenia fluviatilis).

Bhatia, Harpreet
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
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With the detection of anti-androgenicity in the effluents from the wastewater treatment plants (WWTPs), there is speculation that sexual disruption in fish is a multi-causal condition involving anti-androgens. Much of the research has focussed on deciphering the modes-of-action (MoAs) of (anti)estrogens and androgens. However, effects of androgen receptor (AR) antagonists have not been fully characterised and remain elusive in fish. The present study aimed to investigate the effects of the classic mammalian anti-androgen, flutamide and the emerging industrial pollutant, di-n-butyl phthalate (DnBP) on the biomarkers of reproduction in adult (male and female) and juvenile Murray rainbowfish (Melanotaenia fluviatilis). Flutamide is the “pure” anti-androgen designed to treat prostate cancer in men and polycystic ovarian syndrome in women. It has also been extensively used in toxicity testing in mammals. The in vitro anti-androgenic activity in the aquatic environment worldwide is measured in flutamide equivalents. Phthalates are a class of synthetic industrial chemicals commonly found in the aquatic environment worldwide. They have been recognised as anti-androgens in male mammals but little is known about their endocrine-disrupting effects in the native Australian fish species. Due to its detection in freshwater both in Australia and worldwide and considering its higher solubility in water (11 mg/L)...

‣ Oxidative Stress Defines the Neuroprotective or Neurotoxic Properties of Androgens in Immortalized Female Rat Dopaminergic Neuronal Cells

Holmes, Shaletha; Abbassi, Babak; Su, Chang; Singh, Meharvan; Cunningham, Rebecca L.
Fonte: Endocrine Society Publicador: Endocrine Society
Tipo: Artigo de Revista Científica
Português
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Males have a higher risk for developing Parkinson's disease and parkinsonism after ischemic stroke than females. Although estrogens have been shown to play a neuroprotective role in Parkinson's disease, there is little information on androgens' actions on dopamine neurons. In this study, we examined the effects of androgens under conditions of oxidative stress to determine whether androgens play a neuroprotective or neurotoxic role in dopamine neuronal function. Mitochondrial function, cell viability, intracellular calcium levels, and mitochondrial calcium influx were examined in response to androgens under both nonoxidative and oxidative stress conditions. Briefly, N27 dopaminergic cells were exposed to the oxidative stressor, hydrogen peroxide, and physiologically relevant levels of testosterone or dihydrotestosterone, applied either before or after oxidative stress exposure. Androgens, alone, increased mitochondrial function via a calcium-dependent mechanism. Androgen pretreatment protected cells from oxidative stress-induced cell death. However, treatment with androgens after the oxidative insult increased cell death, and these effects were, in part, mediated by calcium influx into the mitochondria. Interestingly, the negative effects of androgens were not blocked by either androgen or estrogen receptor antagonists. Instead...

‣ Endogenous Levels of Circulating Androgens and Risk of Crohn's Disease and Ulcerative Colitis Among Women: A Nested Case–Control Study from the Nurses' Health Study Cohorts

Khalili, Hamed; Ananthakrishnan, Ashwin N.; Konijeti, Gauree G.; Higuchi, Leslie M.; Fuchs, Charles S.; Richter, James M.; Tworoger, Shelley S.; Hankinson, Susan E.; Chan, Andrew T.
Fonte: Lippincott Williams & Wilkins Publicador: Lippincott Williams & Wilkins
Tipo: Artigo de Revista Científica
Português
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Background: Androgens, which are known to be altered by exogenous hormone use, have recently been linked to alterations of the gut microbiome and mucosal immune function. No study has evaluated the association between circulating levels of androgens and risk of Crohn's disease (CD) and ulcerative colitis (UC). Methods: We conducted a nested case–control study of women enrolled in the Nurses' Health Study and Nurses' Health Study II who provided a blood specimen. Cases of CD and UC were each matched to 2 controls. Prediagnosis plasma levels of dehydroepiandrosterone sulfate, testosterone, and sex hormone–binding globulin were measured. We examined the association of each analyte with risk of CD or UC using conditional logistic regression models. Results: Compared with women in the lowest quintile of testosterone, the multivariable-adjusted odds ratios for CD were 0.86 (95% confidence interval, 0.39–1.90) for women in the second quintile, 0.49 (95% confidence interval, 0.21–1.15) for the third quartile, 0.22 (0.08–0.65) for the fourth quintile, and 0.39 (95% confidence interval, 0.16–0.99) for the highest quintile (Plinear trend = 0.004). In contrast, we did not observe a consistent association between prediagnostic testosterone and risk of UC (Plinear trend = 0.84). We also did not observe any association between plasma levels of sex hormone–binding globulin or dehydroepiandrosterone sulfate and risk of UC or CD (all Plinear trends > 0.10). Conclusions: Among women...

‣ Estudi dels mecanismes implicats en la regulació hormonal i cèl·lula específica del gen de la kidney androgen-regulated protein (KAP), en el ronyó de ratolí

Soler Codina, Montse
Fonte: Bellaterra : Universitat Autònoma de Barcelona, Publicador: Bellaterra : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis Formato: application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf; application/pdf
Publicado em //2002 Português
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Consultable des del TDX; Títol obtingut de la portada digitalitzada; L'expressió de la Kidney Androgen-regulated Protein (KAP) està regulada específicament y diferencialment per andrògens i hormona tiroïdal (T3) en el túbul proximal renal. Hem analitzat la transactivació del promotor del gen del KAP en cèl.lules PCT (pars convoluta) i PR (recta) derivades de ratolins transgènics L-PK/Tag1. Transfeccions transitòries amb diferents contruccions del promotor del KAP indicaven que el fragment de 224 bp era suficient per a mediar l'expressió cèl.lula específica de dit promotor. Assaigs de retardament en gel també mostraven que un putatiu element de resposta a andrògens (ARE), local.litzat a -39 bp de l'inici de transcripció, unia el receptor d'andrògens. La dihidrotestosterona (DHT) estimulava de manera androgen dependent la transactivació del KAP en cèl.lules PCT però en PR i la mutació de la putativa seqüència ARE eliminava dita activació. A més a més, l'IGF-1 però no la T3 augmentava la transactivació androgen dependent de KAP en PCT. Per tant, es suggeria que l'efecte cooperatiu de T3 en l'expressió del KAP existia in vivo podent efectar a l'activació produïda per T3 de l'hormona de creixement (GH) i al seu torn d'IGF-1. Aquests resultats demostraven l'expressió específica del curt fragment de 224 bp del promotor del KAP y suggerien interaccions sinèrgiques entre IGF-1 i andrògens en la regulació del gen del KAP en PCT. L'expressió cortical androgen dependent del KAP està afectada en hipotiroïdisme postnatal. La síntesi puntual de T3 a partir del dia 11 postnatal...