Testosterone

About: Testosterone is a research topic. Over the lifetime, 23258 publications have been published within this topic receiving 808079 citations. The topic is also known as: 4-androsten-17beta-ol-3-one & 4-Androsten-3-one-17b-ol.

High-Affinity Androgen Binding and Androgenic Regulation of α1(I)-Procollagen and Transforming Growth Factor-β Steady State Messenger Ribonucleic Acid Levels in Human Osteoblast-Like Osteosarcoma Cells*

Abstract: Clinical observations have demonstrated a positive effect of estrogens and androgens on the maintenance of structural bone integrity. This study examines the direct effects of androgenic hormones on the osteoblast-like human osteosarcoma cell line, HOS TE85. Employing radiolabeled dihydrotestosterone (DHT), 2800 saturable, high-affinity (dissociation constant = 0.66 nM) androgen binding sites were detected per HOS TE85 cell. Androgen binding was specific in that DHT and testosterone (T) displayed significantly greater competition than the progestins, progesterone and medroxyprogesterone. The expression of androgen receptors in HOS TE85 cells was further substantiated by Northern analysis. A human androgen receptor complementary DNA probe revealed a 9.5 kilobase transcript which corresponds to the predominant human androgen receptor transcript detected in human male reproductive tissues. Androgens were also found to elicit biological responses in HOS TE85 cells. Physiological concentrations of DHT and T de...

PFOS (perfluorooctanesulfonate) in serum is negatively associated with testosterone levels, but not with semen quality, in healthy men

Abstract: study question: Is exposure to perfluorinated compounds (PFCs) associated with testicular function (reproductive hormone levels and semen quality) in healthy men? summary answer: PFOS levels were significantly negatively associated with serum testosterone (total and calculated free), but not with any other reproductive hormones or semen quality. what is known already: In animals, some PFCs have endocrine disrupting potential, but few studies have investigated PFCs in relation to human testicular function. Previously, we and others have observed a negative association between serum PFC levels and sperm morphology. The potential associations with reproductive hormones remain largely unresolved. study design, size, duration: A cross-sectional study of 247 men was conducted during 2008– 2009. participants/materials, setting, methods: Healthy men from the general population, median age of 19 years, gave serum and semen samples. Serum samples were analysed for total testosterone (T), estradiol (E), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and inhibin-B and 14 PFCs, including perfluorooctanesulfonate (PFOS). Semen samples were analysed according to the WHO criteria. main results and the role of chance: PFOS levels were negatively associated with testosterone (T), calculated free testosterone (FT), free androgen index (FAI) and ratios of T/LH, FAI/LH and FT/LH. Other PFCs were found at lower levels than PFOS and did not exhibit the same associations. PFC levels were not significantly associated with semen quality. PFOS levels in these samples collected in 2008– 2009 were lower than in our previous study of men participating in 2003. limitations, reasons for caution: Results were robust to adjustment for relevant confounders; however, the possibility of chance associations due to multiple testing or effects of uncontrolled confounding cannot be ruled out. wider implications of the findings: Our previous findings of decreased sperm morphology in the most highly PFC exposed men were not replicated, possibly due to a lack of highly exposed individuals; however, a recent independent study also did corroborate such an inverse association. The negative association between serum PFOS and testosterone indicates that testosterone production may be compromised in individuals with high PFOS exposure.

Sex Steroids, Cardiovascular Disease, and Hypertension: Unanswered Questions and Some Speculations

Abstract: The roles that both male and female sex steroids play in mediating or protecting against cardiovascular disease (CVD) and hypertension are controversial. For example, whereas animal studies have strongly implicated androgens as being mediators of CVD and hypertension, human epidemiological studies have shown that with chronic disease, including hypertension, serum testosterone levels are actually reduced.1 Thus, whether androgens are truly causative of CVD is not clear. However, premenopausal women are typically protected from CVD and hypertension compared with men, and this has been hypothesized to be because of the protective effects of estrogens. The negative findings of Heart and Estrogen/progestin Replacement Study (HERS) I and II2,3 and Women’s Health Initiative (WHI)4,5 studies on hormone replacement therapy (HRT) in postmenopausal women have shaken our previous ideas that HRT was protective against CVD. In this short review, the latest findings regarding the roles of sex steroids in hypertension and CVD are discussed, questions yet to be answered are suggested, and some speculations are made. In both males and females, the hypothalamus secretes gonadotropin-releasing hormone, which stimulates the anterior pituitary to release both luteinizing hormone and follicular-stimulating hormone. Luteinizing hormone binds to receptors on thecal cells in ovaries of females and Leydig cells in testes of males to cause testosterone to be synthesized. Follicular-stimulating hormone, however, binds to receptors on granulosa cells in females or Sertoli cells in males and stimulates the synthesis of aromatase, which converts testosterone to estradiol. There are 2 main types of estrogen receptors, ERα and ERβ, but several variants of both have also been identified. ERβ is present in a greater number of tissues than is ERα, but both isoforms are present in kidneys and the vasculature. ERβ has been found to be the predominant isoform in human vascular smooth muscle cells. The androgen receptor …

Dihydrotestosterone Decreases Tumor Necrosis Factor-α and Lipopolysaccharide-Induced Inflammatory Response in Human Endothelial Cells

Abstract: Context: An increasing body of evidence suggests that testosterone may exert beneficial effects on the development of atherosclerosis. It was suggested that testosterone may act after conversion into estradiol and activation of the estrogen receptors; however, a direct role of androgens on the vascular wall has been proposed. Objective: We investigated the effects of dihydrotestosterone on the proinflammatory response observed in human endothelial cells. Design: Human endothelial cells isolated from umbilical cords were incubated with lipopolysaccharide or TNFα in the presence or absence of dihydrotestosterone (DHT). mRNA and cellular proteins were processed for gene expression studies, and transient transfection experiments were performed to investigate molecular mechanisms involved in the effects observed. Setting: These studies took place at the Department of Pharmacological Sciences, University of Milan, Milan, Italy. Results: Lipopolysaccharide and TNFα induced VCAM-1 and ICAM-1 mRNA and protein expr...