978 resultados para Anabolic hormones


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DO CARMO, E. C., T. FERNANDES, D. KOIKE, N. D. DA SILVA JR., K. C. MATTOS, K. T. ROSA, D. BARRETTI, S. F. S. MELO, R. B. WICHI, M. C. C. IRIGOYEN, and E. M. DE OLIVEIRA. Anabolic Steroid Associated to Physical Training Induces Deleterious Cardiac Effects. Med. Sci. Sports Exerc., Vol. 43, No. 10, pp. 1836-1848, 2011. Purpose: Cardiac aldosterone might be involved in the deleterious effects of nandrolone decanoate (ND) on the heart. Therefore, we investigated the involvement of cardiac aldosterone, by the pharmacological block of AT1 or mineralocorticoid receptors, on cardiac hypertrophy and fibrosis. Methods: Male Wistar rats were randomized into eight groups (n = 14 per group): Control (C), nandrolone decanoate (ND), trained (T), trained ND (TND), ND + losartan (ND + L), trained ND + losartan (TND + L), ND + spironolactone (ND + S), and trained ND + spironolactone (TND + S). ND (10 mg.kg(-1).wk(-1)) was administered during 10 wk of swimming training (five times per week). Losartan (20 mg.kg(-1).d(-1)) and spironolactone (10 mg.kg(-1).d(-1)) were administered in drinking water. Results: Cardiac hypertrophy was increased 10% by using ND and 17% by ND plus training (P < 0.05). In both groups, there was an increase in the collagen volumetric fraction (CVF) and cardiac collagen type III expression (P < 0.05). The ND treatment increased left ventricle-angiotensin-converting enzyme I activity, AT1 receptor expression, aldosterone synthase (CYP11B2), and 11-beta hydroxysteroid dehydrogenase 2 (11 beta-HSD2) gene expression and inflammatory markers, TGF beta and osteopontin. Both losartan and spironolactone inhibited the increase of CVF and collagen type III. In addition, both treatments inhibited the increase in left ventricle-angiotensin-converting enzyme I activity, CYP11B2, 11 beta-HSD2, TGF beta, and osteopontin induced by the ND treatment. Conclusions: We believe this is the first study to show the effects of ND on cardiac aldosterone. Our results suggest that these effects may be associated to TGF beta and osteopontin. Thus, we conclude that the cardiac aldosterone has an important role on the deleterious effects on the heart induced by ND.

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NUNES ALVES, M. J. N., M. R. DOS SANTOS, R. G. DIAS, C. A. AKIHO, M. C. LATERZA, M. U. P. B. RONDON, R. L. DE MORAES MOREAU, and C. E. NEGRAO. Abnormal Neurovascular Control in Anabolic Androgenic Steroids Users. Med. Sci. Sports Exerc., Vol. 42, No. 5, pp. 865-871, 2010. Purpose: Previous studies showed that anabolic androgenic steroids (AAS) increase vascular resistance and blood pressure (BP) in humans. In this study, we tested the hypotheses 1) that AAS users would have increased muscle sympathetic nerve activity (MSNA) and reduced forearm blood flow (FBF) compared with AAS nonusers and 2) that there would be an association between MSNA and 24-h BP. Methods: Twelve AAS users aged 31 +/- 2 yr (means +/- SE) and nine age-matched AAS nonusers aged 29 T 2 yr participated in the study. All individuals were involved in strength training for at least 2 yr. AAS was determined by urine test (chromatography-mass spectrometry). MSNA was directly measured by microneurography technique. FBF was measured by venous occlusion plethysmography. BP monitoring consisted of measures of BP for 24 h. Results: MSNA was significantly higher in AAS users than that in AAS nonusers (29 +/- 3 vs 20 +/- 1 bursts per minute, P = 0.01). FBF (1.92 +/- 0.17 vs 2.77 +/- 0.24 mL.min(-1).100 mL(-1), P = 0.01) and forearm vascular conductance (2.01 +/- 0.17 vs 2.86 +/- 0.31 U, P = 0.02) were significantly lower in AAS users than that in AAS nonusers. Systolic (131 +/- 4 vs 120 +/- 3 mm Hg, P = 0.001), diastolic (74 +/- 4 vs 68 +/- 3 mm Hg, P = 0.02), and mean BP (93 +/- 4 vs 86 +/- 3 mm Hg, P = 0.005) and heart rate (74 +/- 3 vs 68 +/- 3 bpm, P = 0.02) were significantly higher in AAS users when compared with AAS nonusers. Further analysis showed that there was a significant correlation between MSNA and 24-h mean BP (r = 0.75, P = 0.002). Conclusions: AAS increases MSNA and reduces muscle blood flow in young individuals. In addition, the increase in BP levels in AAS users is associated with augmented sympathetic outflow. These findings suggest that AAS increases the susceptibility for cardiovascular disease in humans.

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Calomys callosus is a wild rodent found naturally infected with different Trypanosoma cruzi strains. In the work described here, groups of male and female C callosus were subjected to orchiectomy, ovariectomy and sham operation. One month after surgery, animals were inoculated intraperitoneally (i.p.) with 4 x 10(4) blood trypomastigotes of the ""Y"" strain of T. cruzi. Parasitemia, triglycerides, nitric oxide (NO) and concanavalin A (ConA)-induced proliferation were evaluated. Parasitemia during the course of infection was significantly higher in infected and sham operated animals as compared to infected orchiectomized animals. The opposite was observed in the ovariectomized and infected group. Orchiectomized and infected animals displayed elevated triglyceride levels, as well as a more vigorous immune response, with higher splenocyte proliferation and elevated concentrations of NO. Ovariectomy resulted in an impaired immune response, as observed by a reduction of splenocyte proliferation and NO concentration. The results suggest a pivotal role for gonadal hormones in the modulation of triglyceride levels and the magnitude of the immune response during the acute phase of T. cruzi infection. (C) 2008 Published by Elsevier B.V.

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Interactions between testosterone, estradiol, and inhibin in the control of gonadotrophin secretion in males are poorly understood. Castrated rams were treated with steroid-free bovine follicular fluid (bFF), testosterone, or estradiol and for 7 d (2 x 2 x 2 factorial design). Given independently, none of the exogenous hormones affected follicle-stimulating hormone (FSH) concentrations, but the combination of one or both steroids with bFF reduced FSH secretion. Testosterone and estradiol reduced luteinizing hormone (LH) pulse frequency (there was no synergism), and bFF had no effect. Plasma prolactin concentrations were not affected by any treatment. To locate the central sites of steroid action, castrated rams were bilaterally implanted in the preoptic area (POA), ventromedial nucleus (VMH), or arcuate nucleus (ARC). These implants did not affect FSH or prolactin concentrations, or LH pulse amplitude. The frequency of the LH pulses was not affected by testosterone in any site. Estradiol located in the ARC, but not the POA or VMH, decreased LH pulse frequency. In summary, FSH secretion is controlled by synergistic interactions between inhibin and estradiol or testosterone, whereas GnRH/LH pulse frequency is controlled by testicular steroids. Estradiol acts partly, at least, in the ARC, but the central site of action, testosterone remains unknown.

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H-1 NMR spectra of the thyroid hormone thyroxine recorded at low temperature and high field show splitting into two peaks of the resonance due to the H2,6 protons of the inner (tyrosyl) ring. A single resonance is observed in 600 MHz spectra at temperatures above 185 K. An analysis of the line shape as a function of temperature shows that the coalescence phenomenon is due to an exchange process with a barrier of 37 kJ mol(-1). This is identical to the barrier for coalescence of the H2',6' protons of the outer (phenolic) ring reported previously for the thyroid hormones and their analogues. It is proposed that the separate peaks at low temperature are due to resonances for H2,6 in cisoid and transoid conformers which are populated in approximately equal populations. These two peaks are averaged resonances for the individual H2 and H6 protons. Conversion of cisoid to transoid forms can occur via rotation of either the alanyl side chain or the outer ring, from one face of the inner ring to the other. It is proposed that the latter process is the one responsible for the observed coalescence phenomenon. The barrier to rotation of the alanyl side chain is greater than or equal to 37 kJ mol(-1), which is significantly larger than has previously been reported for Csp(2)-Csp(3) bonds in other Ph-CH2-X systems. The recent crystal structure of a hormone agonist bound to the ligand-binding domain of the rat thyroid hormone receptor (Wagner et al. Nature 1995, 378, 690-697) shows the transoid form to be the bound conformation. The significant energy barrier to cisoid/transoid interconversion determined in the current study combined with the tight fit of the hormone to its receptor suggests that interconversion between the forms cannot occur at the receptor site but that selection for the preferred bound form occurs from the 50% population of the transoid form in solution.

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Menopause is recognized as a period of increased risk for coronary heart disease. Although the benefits of exercise training in lowering cardiovascular risk factors are well established, the risks and benefits of hormone therapy have been questioned. The purpose of the present study was to investigate the effects of estrogen therapy (HT) associated or not with exercise training (ET) in autonomic cardiovascular control in ovariectomized (OVX) rats. Female rats were divided into: control, OVX, OVX+HT, OVX+ET and OVX+HT+ET. HT was performed using a 0.25 mg 8-weeks sustained release pellet. Trained groups were submitted to an 8-week exercise training protocol on treadmill. Baroreflex sensitivity (BRS) was evaluated by heart rate responses to arterial pressure (AP) changes, and vagal and sympathetic tonus by pharmacological blockade. Ovariectomy induced an AP increase (123 +/- 2 mmHg vs. 108 +/- 2 mmHg), BRS impairment (similar to 69%), sympathetic activation (similar to 100%) and vagal tonus reduction (similar to 77%) compared to controls. HT or ET normalized the changes in parasympathetic tonus. However, only the association HT + ET was able to promote normalization of AP, BRS and sympathetic tonus, as compared to controls. These results indicate that ET induces cardiovascular and autonomic benefits in OVX rats under HT, suggesting a positive role of this association in the management of cardiovascular risk factor in postmenopausal women. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

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The industry of ergogenic supplements is increasing rapidly (Cole et al., 2003). Supplements may constitute an important aid for some vigourous exercise routines, but they may also be used as a hypothetical mean to achieve increases in muscular mass. This supposed effect of suplements can lead to its use by individuals who have high levels of drive for muscularity, a condition that is known to be associated with muscular dismorphy (or as it has been called recently vigorexia, Pope et al., 1997). Another psychological factor which can influence supplement consumption is exercise dependence, a borderline problem, as most studies present a prevalence of less than 10% in regular exercisers (Palmeira & Matos, 2006). Symptoms like tolerance or continuity could lead to the use of ergogenic aids to maintain the exercise levels. Also of interest for the understanding of the use of suplements are exercise frequency, volume and intensity, which could explain the ratesof consumption on a more physicological level.

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We report the autopsy of a stillborn fetus with congenital hyperthyroidism born to a mother with untreated Graves' disease, whose cause of death was congestive heart failure. The major findings concerned the skull, thyroid, heart, and placenta. The cranial sutures were closed, with overlapping skull bones. The thyroid was increased in volume and had intense blood congestion. Histological examination showed hyperactive follicles. The heart was enlarged and softened, with dilated cavities and hemorrhagic suffusions in the epicardium. The placenta had infarctions that involved at least 20% of its surface, and the vessels of the umbilical cord were fully exposed due to a decrease in Wharton 's jelly. Hyperthyroidism was confirmed by the maternal clinical data, the fetal findings of exophthalmia, craniosynostosis, and goiter with signs of follicular hyperactivity. Craniosynostosis is caused by the anabolic action of thyroid hormones in bone formation during the initial stages of development. The delayed initiation of treatment in the present case contributed to the severity of fetal hyperthyroidism and consequent fetal death.

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After peripheral nerve injury in adult mammals, reestablishment of functional connections depends on several parameters including neurotrophic factors, the extracellular matrix, and hormones. However, little is known about the contribution of hormones to peripheral nerve regeneration. Thyroid hormones, which are required for the development and maturation of the central nervous system, are also important for the development of peripheral nerves. The action of triiodothyronine (T3) on responsive cells is mediated through nuclear thyroid hormone receptors (TRs) which modulate the expression of specific genes in target cells. Thus, to study the effect of T3, it is first necessary to know whether the target tissues possess TRs. The fact that sciatic nerve cells possess functional TRs suggests that these cells can respond to T3 and, as a consequence, that thyroid hormone may be involved in peripheral nerve regeneration. The silicone nerve guide model provides an excellent system to study the action of local administration of T3. Evidence from such studies demonstrate that animals treated locally with T3 at the level of transection have more complete regeneration of sciatic nerve and better functional recovery. Among the possible regulatory mechanisms by which T3 enhances peripheral nerve regeneration is rapid action on both axotomized neurons and Schwann cells which, in turn, produce a lasting and stimulatory effect on peripheral nerve regeneration. It is probable that T3 up- or down-regulates gene expression of one or more growth factors, extracellular matrix, or cell adhesion molecules, all of which stimulate peripheral nerve regeneration. This could explain the greater effect of T3 on nerve regeneration compared with the effect of any one growth factor or adhesion molecule.

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Anabolic androgenic steroids (AAS) are testosterone derivatives used either clinically, in elite sports, or for body shaping with the goal to increase muscle size and strength. Clinically developed compounds and nonclinically tested designer steroids often marketed as food supplements are widely used. Despite the considerable evidence for various adverse effects of AAS use, the underlying molecular mechanisms are insufficiently understood. Here, we investigated whether some AAS, as a result of a lack of target selectivity, might inhibit 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2)-dependent inactivation of glucocorticoids. Using recombinant human 11β-HSD2, we observed inhibitory effects for several AAS. Whereas oxymetholone, oxymesterone, danazol, and testosterone showed medium inhibitory potential, fluoxymesterone was a potent inhibitor of human 11β-HSD2 (half-maximal inhibitory concentration [IC(50)] of 60-100nM in cell lysates; IC(50) of 160nM in intact SW-620, and 530nM in MCF-7 cells). Measurements with rat kidney microsomes and lysates of cells expressing recombinant mouse 11β-HSD2 revealed much weaker inhibition by the AAS tested, indicating that the adverse effects of AAS-dependent 11β-HSD2 inhibition cannot be investigated in rats and mice. Furthermore, we provide evidence that fluoxymesterone is metabolized to 11-oxofluoxymesterone by human 11β-HSD2. Structural modeling revealed similar binding modes for fluoxymesterone and cortisol, supporting a competitive mode of inhibition of 11β-HSD2-dependent cortisol oxidation by this AAS. No direct modulation of mineralocorticoid receptor (MR) function was observed. Thus, 11β-HSD2 inhibition by fluoxymesterone may cause cortisol-induced MR activation, thereby leading to electrolyte disturbances and contributing to the development of hypertension and cardiovascular disease.