-
Trends in Cardiovascular Medicine Apr 2015Endogenous testosterone levels are inversely associated with cardiovascular risk in older men and men with cardiovascular disease. Current data on cardiovascular... (Review)
Review
Endogenous testosterone levels are inversely associated with cardiovascular risk in older men and men with cardiovascular disease. Current data on cardiovascular outcomes of testosterone therapy include only observational studies and adverse event monitoring in short-term trials that were not designed to measure cardiovascular outcomes. These studies have yielded conflicting results, and some have raised concerns that testosterone therapy may increase cardiovascular risk. A well-designed, adequately powered, prospective trial will ultimately be required to clarify whether testosterone therapy impacts cardiovascular outcomes. This review describes the findings and limitations of recent studies of cardiovascular risk in older men on testosterone therapy and discusses some of the mechanisms through which testosterone may modify cardiovascular risk.
Topics: Adult; Cardiovascular Diseases; Cardiovascular System; Hormone Replacement Therapy; Humans; Male; Risk Factors; Testosterone
PubMed: 25467243
DOI: 10.1016/j.tcm.2014.10.014 -
Asian Journal of Andrology 2015The role of testosterone in the cardiovascular (CV) health of men is controversial. Data suggest that both the condition and treatment of clinical hypogonadism is... (Review)
Review
The role of testosterone in the cardiovascular (CV) health of men is controversial. Data suggest that both the condition and treatment of clinical hypogonadism is associated with decreased CV mortality; however, two recent studies suggest that hypogonadal subjects treated with testosterone replacement therapy have a higher incidence of new CV events. There has been increased media attention concerning the risk of CV disease in men treated with testosterone. Until date, there are no long-term prospective studies to determine safety. Literature spanning over the past 30 years has suggested that not only is there a possible increased CV risk in men with low levels of testosterone, but the benefits from testosterone therapy may even lower this risk. We review here the recent studies that have garnered such intense scrutiny. This article is intended as a thorough review of testosterone levels and CV risk, providing the clinician with the facts needed to make informed clinical decisions in managing patients with clinical hypogonadism.
Topics: Aged; Aged, 80 and over; Cardiovascular Diseases; Eunuchism; Follow-Up Studies; Hormone Replacement Therapy; Humans; Incidence; Male; Risk Factors; Survival Rate; Testosterone
PubMed: 25652628
DOI: 10.4103/1008-682X.146968 -
Molecules (Basel, Switzerland) Dec 2011The Leydig cells of the testis have the capacity to biosynthesize testosterone from cholesterol. Testosterone and its metabolically activated product dihydrotestosterone... (Review)
Review
The Leydig cells of the testis have the capacity to biosynthesize testosterone from cholesterol. Testosterone and its metabolically activated product dihydrotestosterone are critical for the development of male reproductive system and spermatogenesis. At least four steroidogenic enzymes are involved in testosterone biosynthesis: Cholesterol side chain cleavage enzyme (CYP11A1) for the conversion of cholesterol into pregnenolone within the mitochondria, 3β-hydroxysteroid dehydrogenase (HSD3B), for the conversion of pregnenolone into progesterone, 17α-hydroxylase/17,20-lyase (CYP17A1) for the conversion of progesterone into androstenedione and 17β-hydroxysteroid dehydrogenase (HSD17B3) for the formation of testosterone from androstenedione. Testosterone is also metabolically activated into more potent androgen dihydrotestosterone by two isoforms 5α-reductase 1 (SRD5A1) and 2 (SRD5A2) in Leydig cells and peripheral tissues. Many endocrine disruptors act as antiandrogens via directly inhibiting one or more enzymes for testosterone biosynthesis and metabolic activation. These chemicals include industrial materials (perfluoroalkyl compounds, phthalates, bisphenol A and benzophenone) and pesticides/biocides (methoxychlor, organotins, 1,2-dibromo-3-chloropropane and prochloraz) and plant constituents (genistein and gossypol). This paper reviews these endocrine disruptors targeting steroidogenic enzymes.
Topics: Animals; Biotransformation; Endocrine Disruptors; Enzyme Inhibitors; Enzymes; Humans; Metabolic Networks and Pathways; Testosterone
PubMed: 22138857
DOI: 10.3390/molecules16129983 -
The Malaysian Journal of Pathology Dec 2011The number of requests for testosterone testing in adult males has been increasing in recent years. In this review, the biochemistry and physiology of testosterone in... (Review)
Review
The number of requests for testosterone testing in adult males has been increasing in recent years. In this review, the biochemistry and physiology of testosterone in males relevant to the chemical pathologist or clinical biochemist is outlined. The methodology for total testosterone and various laboratory tests associated with the assessment of testosterone status including free testosterone, calculated free testosterone (CFT), bioavailable testosterone (BAT) and free androgen index (FAI) is then summarised. Clinical and laboratory criteria for the diagnosis of late-onset hypogonadism (LOH) in men are critically discussed with particular emphasis on the interpretation of laboratory test results. Finally, other indications for testosterone testing in adult men such as infertility are also reviewed.
Topics: Adult; Blood Chemical Analysis; Humans; Hypogonadism; Male; Testosterone
PubMed: 22299206
DOI: No ID Found -
Psychological Science May 2018Although testosterone is associated with aggression in the popular imagination, previous research on the links between testosterone and human aggression has been...
Although testosterone is associated with aggression in the popular imagination, previous research on the links between testosterone and human aggression has been inconsistent. This inconsistency might be because testosterone's effects on aggression depend on other moderators. In a large adolescent sample ( N = 984, of whom 460 provided hair samples), we examined associations between aggression and salivary testosterone, hair testosterone, and hair cortisol. Callous-unemotional traits, parental monitoring, and peer environment were examined as potential moderators of hormone-behavior associations. Salivary testosterone was not associated with aggression. Hair testosterone significantly predicted increased aggression, particularly at low levels of hair cortisol (i.e., Testosterone × Cortisol interaction). This study is the first to examine the relationship between hair hormones and externalizing behaviors and adds to the growing literature that indicates that androgenic effects on human behavior are contingent on aspects of the broader endocrine environment-in particular, levels of cortisol.
Topics: Adolescent; Adolescent Behavior; Adult; Aggression; Conduct Disorder; Female; Hair; Humans; Hydrocortisone; Male; Saliva; Testosterone; Young Adult
PubMed: 29443645
DOI: 10.1177/0956797617742981 -
Journal of Andrology 1997The number and magnitude of studies involving testosterone-supplementation therapy in older men are limited. In addition, many studies to date have not been blinded or... (Review)
Review
The number and magnitude of studies involving testosterone-supplementation therapy in older men are limited. In addition, many studies to date have not been blinded or controlled, were reported in abstract form only, and had involved a variety of androgen-replacement regimens and outcomes measurements. Nonetheless, an overview of the data suggests there is real potential for supplementation therapy to improve bone mass and muscle mass and strength in this age group. Affects on mood, sexual function, and cognition are less clear but may be meaningful in certain men. Questions still remain, however, on the magnitude and longevity of the beneficial effects of testosterone supplementation in the older man and whether only certain subgroups of men would truly benefit from therapy. More importantly, the long-term risks of androgen therapy in this age group really are not known, especially in the areas of cardiovascular disease and prostate diseases. Presently, men who use androgen-supplementation therapy for age-related "testosterone deficiency" should consider this as a gamble.
Topics: Affect; Aging; Androgens; Bone Density; Cognition; Humans; Male; Muscle Development; Muscle, Skeletal; Sexual Behavior; Testosterone
PubMed: 9154502
DOI: No ID Found -
PloS One 2022Testosterone undecanoate is a hormone agent with long-acting potential and is used for testosterone replacement therapy for hypogonadism. This study was designed to...
Testosterone undecanoate is a hormone agent with long-acting potential and is used for testosterone replacement therapy for hypogonadism. This study was designed to investigate application of testosterone undecanoate in maintaining high androgen levels for inducing benign prostatic hyperplasia more conveniently than that for testosterone propionate. We conducted two-part studies to determine the optimal dosage and dosing cycle for efficient and stable induction of benign prostatic hyperplasia using testosterone undecanoate. In the injection dosage substudy, single testosterone undecanoate dose (125, 250, 500, 750, or 1000 mg/kg body weight) was administered, and the optimal concentration was determined for 8weeks by measuring changes in testosterone, dihydrotestosterone, and 5-alpha reductase levels. And then, testosterone undecanoate was administered at the optimal dose at intervals of 1, 2, 3, or 4 weeks for 12weeks to induce benign prostatic hyperplasia. The injection dosage substudy showed dose-dependently higher and more stable levels of testosterone in groups administrated testosterone undecanoate than in groups administered testosterone propionate. In the injection cycle substudy, testosterone undecanoate-administered group stably maintained high levels of testosterone, dihydrotestosterone, and 5-alpha reductase compared with testosterone propionate-administered group for the same injection cycle; moreover, the prostate measurements, an important sign of benign prostatic hyperplasia, were significantly increased. Based on these two substudies, we determined the optimal conditions for inducing benign prostatic hyperplasia stably and more conveniently than that for testosterone propionate. This study suggests an extended application of testosterone undecanoate for inducing benign prostatic hyperplasia that can improve research reliability considering the half-life of testosterone as well as injection dosage and concentration.
Topics: Animals; Cholestenone 5 alpha-Reductase; Dihydrotestosterone; Humans; Male; Prostatic Hyperplasia; Rats; Rats, Wistar; Reproducibility of Results; Testosterone; Testosterone Propionate
PubMed: 35584179
DOI: 10.1371/journal.pone.0268695 -
International Journal of Environmental... Apr 2019In the present study, the accumulation and degradation of testosterone by were studied. The results showed that C. has a significant ability to eliminate testosterone...
In the present study, the accumulation and degradation of testosterone by were studied. The results showed that C. has a significant ability to eliminate testosterone by bioaccumulation and biodegradation, and during the 96 h experimental period, the data demonstrated that the accumulation of testosterone followed a sigmoidal accumulation pattern. At the end of the experiment, the bioconcentration percentages of testosterone by C. in the high-concentration group and the low-concentration group were 11.49 ± 2.78% and 40.10 ± 1.98%, respectively, and the biodegradation percentages of testosterone were 69.64 ± 4.33% and 42.48 ± 1.92%, respectively. The rate of biodegradation of testosterone by C. mainly depended on the relative initial concentration of testosterone. When the relative initial concentration of testosterone increases, the degradation may gradually change from zero-order kinetics to second-order kinetics.
Topics: Biodegradation, Environmental; Chlorella vulgaris; Kinetics; Testosterone; Water Pollutants, Chemical
PubMed: 30965641
DOI: 10.3390/ijerph16071253 -
Swiss Medical Weekly 2015The term male hypogonadism is defined as the failure to maintain physiological concentrations of testosterone, a physiological quantity of sperm or the combination of... (Review)
Review
The term male hypogonadism is defined as the failure to maintain physiological concentrations of testosterone, a physiological quantity of sperm or the combination of both. Aetiologically, androgen deficiency can originate from the testes (primary hypogonadism) or from the hypothalamic-pituitary regulation of the testicular function (secondary hypogonadism). The causes of hypogonadism are very diverse and may be genetically determined (e.g. Klinefelter's syndrome) or acquired (tumours, infections, haemochromatosis). Classical hypogonadism linked to an underlying disease, such as a pituitary tumour, is a distinct indication for androgen substitution. But how about the aging male? It is known that there is a highly variable age-related decline in testosterone levels; whether this represents a variation of normality or has a true disease value requiring therapy has been disputed over more than a decade. The key questions surrounding this debate concern not only the age-dependent threshold for serum testosterone but, more importantly, the risks and benefits of testosterone replacement therapy in the aging male. We searched the literature for randomised controlled trials of testosterone administration in aging males with a size of at least 100 patients and a follow-up of at least 6 months, and identified eight studies. These studies mostly tried to evaluate the effect of testosterone on bone density, muscle strength and body composition, rather than clinically meaningful endpoints. Moreover, these trials have provided evidence for relevant cardiovascular adverse events in elderly men. This supports the need for further studies to define the treatment threshold for testosterone levels in the aging male, as well as with regard to the long-term risks and relevant benefits of testosterone therapy in this population. Until we have more solid data in aging males, testing for testosterone deficiency and testosterone replacement should remain reserved for patients with predisposing conditions, symptoms and signs of bona fide hypogonadism.
Topics: Aging; Body Composition; Bone Density; Hormone Replacement Therapy; Humans; Hypogonadism; Male; Muscle Strength; Randomized Controlled Trials as Topic; Testosterone
PubMed: 26599486
DOI: 10.4414/smw.2015.14216 -
Philosophical Transactions of the Royal... May 2010Testosterone is essential to maintain spermatogenesis and male fertility. In the absence of testosterone stimulation, spermatogenesis does not proceed beyond the meiosis... (Review)
Review
Testosterone is essential to maintain spermatogenesis and male fertility. In the absence of testosterone stimulation, spermatogenesis does not proceed beyond the meiosis stage. After withdrawal of testosterone, germ cells that have progressed beyond meiosis detach from supporting Sertoli cells and die, whereas mature sperm cannot be released from Sertoli cells resulting in infertility. The classical mechanism of testosterone action in which testosterone activates gene transcription by causing the androgen receptor to translocate to and bind specific DNA regulatory elements does not appear to fully explain testosterone regulation of spermatogenesis. This review discusses two non-classical testosterone signalling pathways in Sertoli cells and their potential effects on spermatogenesis. Specifically, testosterone-mediated activation of phospholipase C and calcium influx into Sertoli cells is described. Also, testosterone activation of Src, EGF receptor and ERK kinases as well as the activation of the CREB transcription factor and CREB-mediated transcription is reviewed. Regulation of germ cell adhesion to Sertoli cells and release of mature sperm from Sertoli cells by kinases regulated by the non-classical testosterone pathway is discussed. The evidence accumulated suggests that classical and non-classical testosterone signalling contribute to the maintenance of spermatogenesis and male fertility.
Topics: Animals; Humans; Male; Spermatogenesis; Testosterone
PubMed: 20403869
DOI: 10.1098/rstb.2009.0258