Serum bioavailability of sex steroid hormones

The toxic effects of anabolic steroids "nandrolone decanoate" on cardiac and skeletal muscles with the potential ameliorative effects of silymarin and fenugreek seeds extract in adult male albino rats

BACKGROUND

Anabolic steroids (AS) are commonly abused by body builders and athletes aiming to increase their strength and muscle mass but unfortunately, the long-term use of AS may lead to serious side effects. Nandrolone Decanoate is one of the Class II anabolic androgenic steroids which quickly spread globally and used clinically and illicitly. Our research was directed to assess the toxic effects of anabolic steroids on cardiac and skeletal muscles in male albino rats and to evaluate the potential ameliorative effects of fenugreek seeds extract and silymarin.

METHODS

Our research was done on 120 male albino rats that were allocated into 6 groups; group I: Served as a control group, group II: Received the anabolic steroid Nandrolone Decanoate, group III: Received silymarin orally, group IV: Received fenugreek seeds extract orally, group (V): Received the anabolic steroid Nandrolone Decanoate and silymarin and group (VI): Received the anabolic steroid Nandrolone Decanoate and fenugreek seeds extract. By the end of the study, rats were sacrificed, and blood samples were collected for biochemical analysis and autopsy samples for histopathological examination.

RESULTS

The anabolic steroids toxic effects on rats showed a significant decrease in serum High Density Lipoprotein (HDL) level and increase in cholesterol, triglycerides, and Low-Density Lipoprotein (LDL) levels. There was a significant elevation in cardiac troponin I level. As regards to histopathological examination of the cardiac and skeletal muscles, the study showed marked degenerative changes and necrosis. Both silymarin and fenugreek seeds extract provided a protective effect on the biochemical and histopathological changes. The antioxidant effects of silymarin and fenugreek seeds extract were evaluated on the heart, skeletal muscles and showed that, the tissue levels of Superoxide dismutase (SOD), Catalase and reduced glutathione (GSH) decreased in AS treated rats compared to the control group. On the other hand, the tissue Malondialdehyde (MDA) levels were elevated.

CONCLUSIONS

Anabolic steroids have a toxic effect on the cardiac and skeletal muscles of albino rats with improvement by treatment with fenugreek seeds extract and silymarin.

Correlations between salivary- and blood-derived gonadal hormone assessments and implications for inclusion of female participants in research studies

Even in the 21st century, female participants continue to be underrepresented in human physiology research. This underrepresentation is attributable in part to the perception that the inclusion of females is more time consuming, less convenient, and more expensive relative to males because of the need to account for the menstrual cycle in cardiovascular study designs. Accounting for menstrual cycle-induced fluctuations in gonadal hormones is important, given established roles in governing vascular function and evidence that failure to consider gonadal hormone fluctuations can result in misinterpretations of biomarkers of cardiovascular disease. Thus, for cardiovascular researchers, the inclusion of females in research studies implies a necessity to predict, quantify, and/or track indexes of menstrual cycle-induced changes in hormones. It is here that methodologies are lacking. Gold standard measurement requires venous blood samples, but this technique is invasive and can become both expensive and technically preclusive when serial measurements are required. To this end, saliva-derived measures of gonadal hormones provide a means of simple, noninvasive hormone tracking. To investigate the feasibility of this technique as a means of facilitating research designs that take the menstrual cycle into account, the purpose of this review was to examine literature comparing salivary and blood concentrations of the primary gonadal hormones that fluctuate across the menstrual cycle: estradiol and progesterone. The data indicate that there appear to be valid and promising applications of salivary gonadal hormone monitoring, which may aid in the inclusion of female participants in cardiovascular research studies.

Approach to androgen excess in women: Clinical and biochemical insights

Androgen excess in women typically presents clinically with hirsutism, acne or androgenic alopecia. In the vast majority of cases, the underlying aetiology is polycystic ovary syndrome (PCOS), a common chronic condition that affects up to 10% of all women. Identification of women with non-PCOS pathology within large cohorts of patients presenting with androgen excess represents a diagnostic challenge for the endocrinologist, and rare pathology including nonclassic congenital adrenal hyperplasia, severe insulin resistance syndromes, Cushing's disease or androgen-secreting tumours of the ovary or adrenal gland may be missed in the absence of a pragmatic screening approach. Detailed clinical history, physical examination and biochemical phenotyping are critical in risk-stratifying women who are at the highest risk of non-PCOS disorders. Red flag features such as rapid onset symptoms, overt virilization, postmenopausal onset or severe biochemical disturbances should prompt investigations for underlying neoplastic pathology, including dynamic testing and imaging where appropriate. This review will outline a proposed diagnostic approach to androgen excess in women, including an introduction to androgen metabolism and provision of a suggested algorithmic strategy to identify non-PCOS pathology according to clinical and biochemical phenotype.

Accurate measurement of total and free testosterone levels for the diagnosis of androgen disorders

The circulating concentrations of total and free testosterone vary substantially in people over time due to biologic factors as well as due to measurement variation. Accurate measurement of total and free testosterone is essential for making the diagnosis of androgen disorders. Total testosterone should ideally be measured in a fasting state in the morning using a reliable assay, such as liquid chromatography tandem mass spectrometry, in a laboratory that is certified by an accuracy-based benchmark. Free testosterone levels should be measured in men in whom alterations in binding protein concentrations are suspected or in whom total testosterone levels are only slightly above or slightly below the lower limit of the normal male range for testosterone.

Accurate Measurement and Harmonized Reference Ranges for Total and Free Testosterone Levels

Diagnosing testosterone deficiency requires accurate and precise measurement of total testosterone levels by an accurate method, such as liquid chromatography-tandem mass spectrometry in a laboratory certified by an accuracy-based program (eg, Centers for Disease Control and Prevention's Hormone Standardization (HoST) Program), and, if needed, free testosterone level. Free testosterone level should ideally be measured by equilibrium dialysis method. Testosterone levels should be measured in 2 or more fasting samples obtained in the morning. Harmonized reference ranges for total testosterone can be applied to laboratories that certified by the HoST Program.

Role of sex steroids hormones in the regulation of bone metabolism in men: Evidence from clinical studies

Sex steroids regulate bone metabolism in young men during growth and consolidation. Their deficit during growth compromises longitudinal and radial growth of bones and has a negative impact on body height, bone width, peak areal bone mineral density (aBMD) and bone microarchitecture. In older men, the deficit of sex steroid hormones (mainly 17β-oestradiol) contributes to high bone turnover rate, low aBMD, poor bone microarchitecture, low estimated bone strength, accelerated bone loss and rapid decline of bone microarchitecture. The role of 17β-oestradiol is confirmed by the case of men with congenital oestrogen receptor deficit and with congenital aromatase deficiency. 17β-oestradiol inhibits bone resoption, whereas both hormones regulate bone formation. However, the associations are weak. Prospective data on the utility of blood 17β-oestradiol or testosterone for fracture risk assessment are inconsistent. Men with hypogonadism have decreased aBMD and poor bone microarchitecture. In men with hypogonadism, testosterone replacement therapy increases aBMD and improves bone microarchitecture. In men with prostate cancer, androgen deprivation therapy (gonadoliberin analogues) induces rapid bone loss and severe deterioration of bone microarchitecture.

Metabolism of testosterone during weight loss in men with obesity

OBJECTIVE

Men with obesity often have low total and, with increasing adiposity, also low free testosterone (T) levels, which can partially restore during weight loss. Although this is partly explained by lower sex hormone binding globulin (SHBG) production and hypothalamic-pituitary downregulation, it is still not unravelled whether changes in androgen metabolism contribute to this phenomenon. Therefore, early changes in urinary excretion of T and its metabolites, during weight loss, in men with obesity are investigated.

DESIGN

Longitudinal study.

METHODS

Fourteen men with obesity (age 52(45-60)years, BMI 42.6(41.8-44.8)kg/m²) underwent gastric bypass surgery (GBS). Before surgery and 3 weeks, 6 weeks, 6 months and 1 year thereafter, 24 h urine and fasting serum samples were collected. Serum T and estradiol (E₂) levels were analyzed using LC-MS/MS and urinary metabolites of T with GC-MS/MS.

RESULTS

Already three weeks after GBS, serum SHBG and total T levels increased and remained increased as compared to baseline (all,p < 0.0125). Gonadotropins and (free) E₂ levels were unchanged, serum E₂/T ratio decreased (p < 0.0125). Total amount of urinary T increased non-significantly with mean increases of 53 % one year after GBS (p = 0.026). Urinary E₂/T, estrone/T, 3α-androstanediol/T and androsterone/T ratios decreased after GBS (p < 0.0125).

CONCLUSIONS

Restoration of circulating T levels during weight loss in this population is not only brought about by normalization of circulating SHBG levels, but increased production of and alterations in T metabolism also contribute. More specifically, relative decreases in aromatization and lower 5α-reductase activity might also be involved in restoring T levels in men with obesity.

Androgen deprivation therapy and risk of cognitive dysfunction in men with prostate cancer: is there a possible link?

The expansion of the indication to use androgen deprivation therapy (ADT) to treat patients with advanced or metastatic prostate cancer has dramatically increased over the recent decades, resulting in the progress of patients’ survival. However, chronic health implications can become more apparent as the number of long-term cancer survivors is expected to be increased along with the adverse effect of ADT. In particular, interest in investigating ADT, especially luteinizing hormone-releasing hormone (LHRH) agonist association with cognitive dysfunction has been growing. Previous studies in animals and humans suggest that the level of androgen decreases with age and that cognitive decline occurs with decreases in androgen. Correspondingly, some of the extensive studies using common neurocognitive tests have shown that LHRH agonists may affect specific domains of cognitive function (e.g., visuospatial abilities and executive function). However, the results from these studies have not consistently demonstrated the association because of its intrinsic limitations. Large-scale studies based on electronic databases have also failed to show consistent results to make decisive conclusions because of its heterogeneity, complexity of covariates, and possible risk of biases. Thus, this review article summarizes key findings and discusses the results of several studies investigating the ADT association with cognitive dysfunction and risk of dementia from various perspectives.

Bioidentical hormones

After the results of the Women's Health Initiative trials were published, patient and clinician interest in potential alternatives to conventional hormone therapy (HT) has grown. A commonly used alternative therapy involves custom-compounded steroid hormone preparations, formulated by compounding pharmacies. Many postmenopausal women consider the hormones as natural or bioidentical, in contrast to hormones used in conventional HT, which they consider synthetic. In actuality, the chemical structures of many of the hormones used in bioidentical HT (BHT) are the same as those used in conventional HT. To customize formulations, compounding pharmacies frequently use saliva testing to measure hormones. However, there is a misconception that salivary hormone levels are equivalent to non-protein-bound (free) hormones in blood. Because hormonal custom-compounded formulations are not approved by the Food and Drug Administration (FDA), there are concerns regarding their purity, potency, and quality. Evolving regulatory guidelines by the FDA on oversight of these products should lessen the concerns regarding their safety and efficacy. This review addresses important misconceptions and uncertainties pertaining to BHT, the relationship between salivary and serum/plasma steroid hormone concentrations, the effect of topical progesterone creams on the endometrium, the variability in custom-compounded steroid preparations, and FDA oversight of custom-compounded products.

Association between metabolic syndrome, hepatic steatosis, and testosterone deficiency: evidences from studies with men and rodents

Testosterone is the predominant androgen in men and the lack of it can be a trigger to the development of the metabolic syndrome. Here we review the relationship between testosterone deficiency, metabolic syndrome, and hepatic steatosis reported by studies with men and rodents. The prevalence of metabolic syndrome and testosterone deficiency is higher among older subjects. Low total and free testosterone levels were positively associated with disturbs on energy metabolism, changes in body fat distribution, and body composition. Studies reported visceral fat accumulation in men with hypogonadism and castrated rats. Despite some contradictions, the association between higher adiposity, low testosterone, and metabolic syndrome was a common point among the studies. Few studies evaluated the hepatic steatosis and found an association with hypogonadism. Most of the studies with rodents combined the castration with a high-fat diet to study metabolic disturbs. The importance of proper levels of testosterone for energy metabolism homeostasis in men was also underlined by studies that investigated the metabolic effects of testosterone replacement therapy and androgen deprivation therapy.

Nandrolone Decanoate: Use, Abuse and Side Effects

Background and Objectives: Androgens play a significant role in the development of male reproductive organs. The clinical use of synthetic testosterone derivatives, such as nandrolone, is focused on maximizing the anabolic effects and minimizing the androgenic ones. Class II anabolic androgenic steroids (AAS), including nandrolone, are rapidly becoming a widespread group of drugs used both clinically and illicitly. The illicit use of AAS is diffused among adolescent and bodybuilders because of their anabolic proprieties and their capacity to increase tolerance to exercise. This systematic review aims to focus on side effects related to illicit AAS abuse, evaluating the scientific literature in order to underline the most frequent side effects on AAS abusers’ bodies. Materials and Methods: A systematic review of the scientific literature was performed using the PubMed database and the keywords “nandrolone decanoate”. The inclusion criteria for articles or abstracts were English language and the presence of the following words: “abuse” or “adverse effects”. After applying the exclusion and inclusion criteria, from a total of 766 articles, only 148 were considered eligible for the study. Results: The most reported adverse effects (found in more than 5% of the studies) were endocrine effects (18 studies, 42%), such as virilization, gynecomastia, hormonal disorders, dyslipidemia, genital alterations, and infertility; cardiovascular dysfunctions (six studies, 14%) such as vascular damage, coagulation disorders, and arteriosus hypertension; skin disorders (five studies, 12%) such as pricking, acne, and skin spots; psychiatric and mood disorders (four studies, 9%) such as aggressiveness, sleep disorders and anxiety; musculoskeletal disorders (two studies, 5%), excretory disorders (two studies, 5%), and gastrointestinal disorders (two studies, 5%). Conclusions: Based on the result of our study, the most common adverse effects secondary to the abuse of nandrolone decanoate (ND) involve the endocrine, cardiovascular, skin, and psychiatric systems. These data could prove useful to healthcare professionals in both sports and clinical settings.

The applications of androgen in the treatment of dry eye disease: a systematic review of clinical studies

Androgen regulates the function of lacrimal and meibomian glands, and its deficiency is a pathological factor underlying dry eye disease (DED). However, no androgen has been approved for treating DED due to lack of definite evidence regarding its efficacy and safety in clinics. In this systematic review, we have summarized the clinical studies on the safety and efficacy of androgen replacement therapy (ART) for DED. Medline (via Pubmed), Embase, Clinicaltrials.gov, Wanfang and Chinese Clinical Trials Registry Database were searched for the relevant prospective studies, and 7 studies wherein androgen was applied topically via eye drops or systemically via oral or transdermal administration were included. The quality of these studies was assessed with the Cochrane Collaboration's tool for assessing risk of bias and methodological index for non-randomized studies. Most studies showed that androgen effectively improved dry eye-related symptoms and increased tear secretion. Furthermore, elderly men and peri-menopausal women with lower levels of circulating androgens responded better to ART. However, one study involving patients with Sjögren's syndrome showed no improvement in the ART group compared to the placebo control, or to the baseline level. Adverse effects were also common but limited to mild skin problems. In conclusion, androgen is a potential treatment for dry eye disease, especially for people with primary androgen deficiency. Short-term application is relatively safe.

Urinary equol is associated with bioavailable testosterone but not total testosterone in women

Little is known about the association between equol and bioavailable testosterone (BT) in adults. In this study, we examined the associations of urinary equol concentrations with serum concentrations of total, bioavailable and free testosterone (FT), dehydroepiandrosterone sulfide (DHEAS), free androgen index (FAI) and sex hormone-binding globulin (SHBG). This cross-sectional study included 1,904 women with a mean age of 59.7 years. Urinary equol concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The serum androgenic indices and SHBG were also determined. Overall, urinary equol tended to be inversely associated with bioactive forms of androgenic indices (BT, FT or FAI) but not with total testosterone (TT) or DHEAS. Urinary equol was also positively associated with SHBG. In multi-covariate-adjusted analyses stratified by menopausal status, graded and inverse associations between urinary equol and bioactive forms of androgenic indices (BT, FT and FAI) were observed in postmenopausal women (all p-trends < 0.05), but not in premenopausal women. A significant positive association between urinary equol and SHBG was observed only in postmenopausal women. No significant associations were observed between urinary equol and TT or DHEAS in either group. A path analysis indicated that these associations of equol with androgens in postmenopausal women might be mediated by SHBG. In conclusion, urinary equol exhibited graded and inverse associations with BT or FT, but not TT in women. However, further longitudinal studies of human patients are needed to confirm these results and overcome the limitations of cross-sectional studies.

Transcriptional coactivator with PDZ-binding motif suppresses the expression of steroidogenic enzymes by nuclear receptor 4 A1 in Leydig cells

Transcriptional coactivator with PDZ-binding motif (TAZ) plays crucial role in maintaining testicular structure and function via regulation of senescence of spermatogenic cells. However, it remains unclear whether TAZ is involved in testosterone biosynthesis in testicular Leydig cells. We found that TAZ deficiency caused aberrant Leydig cell expansion and increased lipid droplet formation, which was significantly associated with increased lipogenic enzyme expression. Additionally, the expression of key steroidogenic enzymes, including steroidogenic acute regulatory protein, cytochrome P450 (CYP) 11A1, CYP17A1, and 3β-hydroxysteroid dehydrogenase, was greatly increased in TAZ-deficient testes and primary Leydig cells. Interestingly, the transcriptional activity of nuclear receptor 4 A1 (NR4A1) was dramatically suppressed by TAZ; however, the protein expression and the subcellular localization of NR4A1 were not affected by TAZ. TAZ directly associated with the N-terminal region of NR4A1 and substantially suppressed its DNA-binding and transcriptional activities. Stable expression of TAZ in the mouse Leydig TM3 cell line decreased the expression of key steroidogenic enzymes, whereas knockdown of endogenous TAZ in TM3 cells increased transcripts of steroidogenic genes induced by NR4A1. Consistently, testosterone production was enhanced within TAZ-deficient Leydig cells. However, TAZ deficiency resulted in decreased testosterone secretion caused by dysfunctional mitochondria and lysosomes. Therefore, TAZ plays essential role in NR4A1-induced steroidogenic enzyme expression and testosterone production in Leydig cells.

Free testosterone correlated with erectile dysfunction severity among young men with normal total testosterone

Erectile dysfunction (ED) due to androgen deficiency is rare in the young population. We retrospectively evaluated in this study men aged 18-40 years presenting with ED from 2015 to 2017. The International Index of Erectile Function-5 (IIEF-5) and Erection Hardness Grade Scores (EHGS) were used to assess erectile function. Total testosterone (TT), sex hormone-binding globulin (SHBG), lipid profile, and glycometabolic indicators were tested in fasting blood sample. TT and SHBG were detected by electrochemiluminescence immunoassay, and free (FT) and bio-available testosterone (BT) were calculated from a validated formula. Linear regression was used to analyze the data. In total, 140 cases (30.56 ± 4.81 years) with a mean TT levels of 6.15 ± 2.17 ng/ml were enrolled. Decreased levels of FT were associated with lower IIEF-5 scores(β = 0.176, P = 0.048) and EHGS (β = 0.198, P = 0.026) after adjustment for age, body mass index (BMI), smoking, comorbidities, high-sensitive C-reactive protein (hsCRP), uric acid, fructosamine, and quantitative insulin sensitivity check index (QUICKI). TT was only associated with EHGS in the crude model (β = 0.177, P = 0.037) and some single factor adjustment models, whereas BT and SHBG were not related with erectile function in any model. Low FT level, even in the presence of normal TT, is associated with ED severity in young men. FT levels should be screened in ED patient even with normal total testosterone.

Reassessing Free-Testosterone Calculation by Liquid Chromatography-Tandem Mass Spectrometry Direct Equilibrium Dialysis

CONTEXT

Assessment of free testosterone (FT) might help evaluate androgen status in patients with borderline total testosterone (T) and/or altered sex hormone-binding globulin (SHBG) levels. However, the validity of different methods to measure FT is debatable.

METHODS

Serum from 183 women and 146 men was analyzed using equilibrium dialysis (ED), with FT directly measured by liquid chromatography-tandem mass spectrometry. FT calculation was re-evaluated for the mass action law-based equation according to Vermeulen (cFT-V), empirical equations according to Ly (cFT-L), and a proposed calculation based on a multistep, dynamic, allosteric model according to Zakharov (cFT-Z).

RESULTS

FT level analyzed by ED [median,13 pmol/L (1.2% of T) in women; 248 pmol/L (1.5% of T) in men] was strongly inversely correlated to SHBG level, significantly to albumin level in women, and only weakly to SHBG level in men. The median [percentile (p) range, 2.5 to 97.5] ratios of calculated FT (cFT) over ED-FT (from European Male Aging Study samples) were 1.19 (0.9 to 1.47), 1.00 (0.69 to 1.42), and 2.05 (1.26 to 3.26) for cFT-V, cFT-L, and cFT-Z, respectively. The ratio for cFT-V was not significantly affected by SHBG, T, or albumin levels (ρ range, 0.17 to -0.01); ratios for cFT-L and cFT-Z were affected (P < 0.05 and P < 0.001, respectively) and strongly correlated with SHBG levels (ρ = 0.72 and 0.75, respectively). Rank correlations between cFT% and ED-FT% (for men) were 0.62, 0.74, and 0.89 for cFT-Z, cFT-L, and cFT-V, respectively.

CONCLUSION

FT results by direct ED confirm prior FT data from indirect ED and ultrafiltration methodologies. Calculations have inherent limitations, with clinically important differences among evaluated equations: cFT-V, although overestimating FT level, appears the most robust approximation, largely independent of SHBG, albumin, and T levels.

MANAGEMENT OF ENDOCRINE DISEASE Hyperandrogenic states in women: pitfalls in laboratory diagnosis

Measuring total testosterone level is the first-line approach in assessing androgen excess in women. The main pitfalls in measuring testosterone relate to its low concentration and to the structural similarity between circulating androgens and testosterone, requiring accurate techniques with high specificity and sensitivity. These goals can be achieved by immunoassay using a specific anti-testosterone monoclonal antibody, ideally after an extraction step. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) will be commonly used for measuring testosterone, providing optimal accuracy with a low limit of detection. Yet, the pitfalls of these two techniques are well identified and must be recognized and systematically addressed. In general, laboratories using direct testosterone immunoassay and mass spectrometry need to operate within a quality framework and be actively engaged in external quality control processes and standardization, so as to ensure appropriate interpretation irrespective of the particular laboratory. Circulating testosterone is strongly bound to sex-hormone-binding globulin (SHBG), and SHBG levels are typically low in overweight hyperandrogenic patients. Thus, low SHBG may decrease circulating testosterone to normal values, which will mask androgen excess status. One way to avoid this pitfall, awaiting direct free testosterone assays that are yet to be developed, is to measure SHBG and calculate free testosterone. A few other pitfalls will be discussed in this review, including those of adrenal androgen exploration, with the aim of helping clinicians to better handle laboratory investigation of androgen excess disorders in women.

Modulation of Tryptophan and Serotonin Metabolism as a Biochemical Basis of the Behavioral Effects of Use and Withdrawal of Androgenic-Anabolic Steroids and Other Image- and Performance-Enhancing Agents

Modulation of tryptophan (Trp) metabolism may underpin the behavioral effects of androgenic-anabolic steroids (AAS) and associated image and performance enhancers. Euphoria, arousal, and decreased anxiety observed with moderate use and exercise may involve enhanced cerebral serotonin synthesis and function by increased release of albumin-bound Trp and estrogen-mediated liver Trp 2,3-dioxygenase (TDO) inhibition and enhancement of serotonin function. Aggression, anxiety, depression, personality disorders, and psychosis, observed on withdrawal of AAS or with use of large doses, can be caused by decreased serotonin synthesis due to TDO induction on withdrawal, excess Trp inhibiting the 2 enzymes of serotonin synthesis, and increased cerebral levels of neuroactive kynurenines. Exercise and excessive protein and branched-chain amino acid intakes may aggravate the effects of large AAS dosage. The hypothesis is testable in humans and experimental animals by measuring parameters of Trp metabolism and disposition and related metabolic processes.

Linking physiologically-based pharmacokinetic and genome-scale metabolic networks to understand estradiol biology

Background

Estrogen is a vital hormone that regulates many biological functions within the body. These include roles in the development of the secondary sexual organs in both sexes, plus uterine angiogenesis and proliferation during the menstrual cycle and pregnancy in women. The varied biological roles of estrogens in human health also make them a therapeutic target for contraception, mitigation of the adverse effects of the menopause, and treatment of estrogen-responsive tumours. In addition, endogenous (e.g. genetic variation) and external (e.g. exposure to estrogen-like chemicals) factors are known to impact estrogen biology. To understand how these multiple factors interact to determine an individual’s response to therapy is complex, and may be best approached through a systems approach.

Methods

We present a physiologically-based pharmacokinetic model (PBPK) of estradiol, and validate it against plasma kinetics in humans following intravenous and oral exposure. We extend this model by replacing the intrinsic clearance term with: a detailed kinetic model of estrogen metabolism in the liver; or, a genome-scale model of liver metabolism. Both models were validated by their ability to reproduce clinical data on estradiol exposure. We hypothesise that the enhanced mechanistic information contained within these models will lead to more robust predictions of the biological phenotype that emerges from the complex interactions between estrogens and the body.

Results

To demonstrate the utility of these models we examine the known drug-drug interactions between phenytoin and oral estradiol. We are able to reproduce the approximate 50% reduction in area under the concentration-time curve for estradiol associated with this interaction. Importantly, the inclusion of a genome-scale metabolic model allows the prediction of this interaction without directly specifying it within the model. In addition, we predict that PXR activation by drugs results in an enhanced ability of the liver to excrete glucose. This has important implications for the relationship between drug treatment and metabolic syndrome.

Conclusions

We demonstrate how the novel coupling of PBPK models with genome-scale metabolic networks has the potential to aid prediction of drug action, including both drug-drug interactions and changes to the metabolic landscape that may predispose an individual to disease development.

Electronic supplementary material

The online version of this article (10.1186/s12918-017-0520-3) contains supplementary material, which is available to authorized users.

A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications

In the circulation, testosterone and other sex hormones are bound to binding proteins, which play an important role in regulating their transport, distribution, metabolism, and biological activity. According to the free hormone hypothesis, which has been debated extensively, only the unbound or free fraction is biologically active in target tissues. Consequently, accurate determination of the partitioning of testosterone between bound and free fractions is central to our understanding of how its delivery to the target tissues and biological activity are regulated and consequently to the diagnosis and treatment of androgen disorders in men and women. Here, we present a historical perspective on the evolution of our understanding of the binding of testosterone to circulating binding proteins. On the basis of an appraisal of the literature as well as experimental data, we show that the assumptions of stoichiometry, binding dynamics, and the affinity of the prevailing models of testosterone binding to sex hormone-binding globulin and human serum albumin are not supported by published experimental data and are most likely inaccurate. This review offers some guiding principles for the application of free testosterone measurements in the diagnosis and treatment of patients with androgen disorders. The growing number of testosterone prescriptions and widely recognized problems with the direct measurement as well as the computation of free testosterone concentrations render this critical review timely and clinically relevant.

Baby babbling at five months linked to sex hormone levels in early infancy

Gender-dependent differentiation of the brain at morphological, neurochemical and functional levels of organization have been shown to be primarily controlled by sex differences in gonadal hormone concentrations during pre- and early postnatal development. Indeed, previous studies have reported that pre- and perinatal hormonal environments influence brain development and, consequently, affect sex specific long-term language outcomes. Herein, we investigated whether postnatal surges of estrogen (estradiol) and androgen (testosterone) may predict properties of pre-speech babbling at five months. This study is the first attempt to investigate a possible correlation between sex hormones and infants' articulatory skills during the typical postnatal period of extended hormonal activity known as 'mini-puberty.' A hierarchical, multiple regression approach revealed a significant, robust positive relationship between 4-week concentrations of estradiol and individual articulatory skills. In contrast, testosterone concentrations at five months negatively correlated with articulatory skills at the same age in both boys and girls. Our findings reinforce the assumption of the importance of sex hormones for auditory-vocal development towards language in human infants.

Fundamental Frequency of Crying in Two-month-old Boys and Girls: Do Sex Hormones During Mini-puberty Mediate Differences?

OBJECTIVE

To evaluate whether the puberty-like sex hormone surge during the first months of life (mini-puberty) affects fundamental frequency (fo) in infant crying as one would derive from hormone influences on voice in adults.

STUDY DESIGN

Populational prospective study.

PARTICIPANTS

Twenty healthy normal-hearing infants (nine boys) were recruited for participation.

METHODS

Spontaneously uttered cries were collected from each infant at 8 weeks of age. The cries were acoustically analyzed for mean fo and fo range. The fo properties were correlated to the average serum levels of bioavailable estradiol (E2) (mean E2/sex hormone-binding globulin [SHBG]) and testosterone (T) (mean T/SHBG) across the second month of life.

RESULTS

Whereas no significant hormone effect was found for mean fo, a significant negative correlation (r = -0.55) was found between fo range and mean E2/SHBG. No indication for a T influence on fo features was found at this age. Although girls showed a slightly higher mean E2 concentration than boys did, the observed differences in cry fo range were judged to be reflective of an infant's serum concentration of E2 rather than a sex-based difference.

CONCLUSION

In the absence of laryngeal size differences between female and male infants, the result was interpreted as indicative of an E2 influence on viscoelastic properties of the vocal folds. In our opinion, the investigation of young infants' vocalizations during the early postnatal surge of sex steroids (mini-puberty) may advance our understanding of the mechanisms mediating average sex differences in vocal development and early communication.

The impact of nandrolone decanoate on the central nervous system

Nandrolone is included in the class II of anabolic androgenic steroids (AAS) which is composed of 19-nor-testosterone-derivates. In general, AAS is a broad and rapidly increasing group of synthetic androgens used both clinically and illicitly. AAS in general and nandrolone decanoate (ND) in particular have been associated with several behavioral disorders. The purpose of this review is to summarize the literature concerning studies dealing with ND exposure on animal models, mostly rats that mimic human abuse systems (i.e. supraphysiological doses). We have focused in particular on researches that have investigated how ND alters the function and expression of neuronal signaling molecules that underlie behavior, anxiety, aggression, learning and memory, reproductive behaviors, locomotion and reward.

Hepatocyte spheroid culture on fibrous scaffolds with grafted functional ligands as an in vitro model for predicting drug metabolism and hepatotoxicity

The identification of a biologic substrate for maintaining hepatocyte functions is essential to provide reliable and predictable models for in vitro drug screening. In the current study, a three-dimensional culture of hepatocytes was established on highly porous fibrous scaffolds with grafted galactose and RGD to afford extensive cell-cell and cell-scaffold interactions spatially. The pore size and ligand densities indicated significant effects on the formation of hepatocyte spheroids in balancing the cell retention, adhesion, and migration on fibrous scaffolds. Fibrous scaffolds with an average pore size of 60 μm and surface grafting densities of galactose at 5.9 nmol/cm(2) and RGD at 6.9 pmol/cm(2) provided optimal microenvironments for hepatocyte infiltration and multicellular spheroid formation. Significant promotions were also demonstrated in the syntheses of albumin and urea and the activities of phase I (CYP 3A11 and CYP 2C9) and phase II enzymes. The in vitro metabolism tests on testosterone and acetaminophen by hepatocytes on the optimal scaffolds indicated the predicated clearance rates of 50.7 and 22.6 ml/min/kg, respectively, which were comparable to the in vivo values of rats. The in vitro hepatotoxicity tests on amiodarone hydrochloride and acetaminophen predicted the half maximal effective concentrations (EC50) to reflect the in vivo toxic plasma concentrations in human. In addition, the enzyme activities, predicted clearance rates and hepatotoxicity values of hepatocytes on the optimal scaffolds experienced sensitive responsiveness to specific inducers or inhibitors of CYP 3A11 and phase II enzymes, exhibiting in vivo-in vitro correlations to a certain extent. These results demonstrate the feasibility of hepatocyte spheroid culture on fibrous scaffolds as an potential in vitro testing model to predict the in vivo drug metabolism, hepatotoxicity, and drug-drug interactions.

Upper-body resistance exercise augments vastus lateralis androgen receptor-DNA binding and canonical Wnt/β-catenin signaling compared to lower-body resistance exercise in resistance-trained men without an acute increase in serum testosterone

The purpose of the study was to determine the effect of single bouts of lower-body (LB) and upper- and lower-body (ULB) resistance exercise on serum testosterone concentrations and the effects on muscle testosterone, dihydrotestosterone (DHT), androgen receptor (AR) protein content, and AR-DNA binding. A secondary purpose was to determine the effects on serum wingless-type MMTV integration site (Wnt4) levels and skeletal muscle β-catenin content. In a randomized cross-over design, exercise bouts consisted of a LB and ULB protocol, and each bout was separated by 1 week. Blood and muscle samples were obtained before exercise and 3 and 24h post-exercise; blood samples were also obtained at 0.5, 1, and 2 h post-exercise. Statistical analyses were performed by separate two-way factorial analyses of variance (ANOVA) with repeated measures. No significant differences from baseline were observed in serum total and free testosterone and skeletal muscle testosterone and DHT with either protocol (p>0.05). AR protein was significantly increased at 3 h post-exercise and decreased at 24 h post-exercise for ULB, whereas AR-DNA binding was significantly increased at 3 and 24h post-exercise (p<0.05). In response to ULB, serum Wnt4 was significantly increased at 0.5, 1, and 2 h post-exercise (p<0.05) and β-catenin was significantly increased at 3 and 24 h post-exercise (p<0.05). It was concluded that, despite a lack of increase in serum testosterone and muscle androgen concentrations from either mode of resistance exercise, ULB resistance exercise increased Wnt4/β-catenin signaling and AR-DNA binding.

Androgens and esophageal cancer: What do we know?

Significant disparities exist between genders for the development and progression of several gastro-intestinal (GI) diseases including cancer. Differences in incidence between men vs women for colon, gastric and hepatocellular cancers suggest a role for steroid sex hormones in regulation of GI carcinogenesis. Involvement of intrinsic gender-linked mechanisms is also possible for esophageal adenocarcinoma as its incidence is disproportionally high among men. However, the cause of the observed gender differences and the potential role of androgens in esophageal carcinogenesis remains unclear, even though the cancer-promoting role of androgen receptors (AR) shown in other cancers such as prostate and bladder suggests this aspect warrants exploration. Several studies have demonstrated expression of ARs in esophageal cancer. However, only one study has suggested a potential link between AR signaling and outcome - poorer prognosis. Two groups have analyzed data from cohorts with prostate cancer and one of these found a decreased incidence of esophageal squamous and adenocarcinoma after androgen deprivation therapy. However, very limited information is available about the effects of androgen and AR-initiated signaling on esophageal cancer cell growth in vitro and in vivo. Possible mechanisms for androgens/AR involvement in the regulation of esophageal cancer growth are considered, and the potential use of AR as a prognostic factor and clinical target is highlighted, although insufficient evidence is available to support clinical trials of novel therapies. As esophageal adenocarcinoma is a gender linked cancer with a large male predominance further studies are warranted to clarify the role of androgens and ARs in shaping intracellular signaling and genomic responses in esophageal cancer.

Transdermal delivery of testosterone

Male hypogonadism has been treated with exogenous testosterone since the 1930s. The early transdermal patches of testosterone became available in the 1980s with gel and solution preparations following subsequent decades. This review focusses on the skin permeation characteristics of testosterone, pharmacokinetics following application of transdermal formulations and formulations currently available. At present, gels dominate the market for transdermal testosterone replacement therapy, presumably because of their greater patient acceptability and non-occlusive nature compared with patches. However, specific incidences of secondary transfer of gels to children with consequent unwanted effects such as precocious puberty have been reported. A regulatory review of all testosterone replacement therapies is currently underway which may have implications for future prescribing practices of transdermal testosterone products.

Off-label use of hormones as an antiaging strategy: a review

Given demographic evolution of the population in modern societies, one of the most important health care needs is successful aging with less frailty and dependency. During the last 20 years, a multitude of anti-aging practices have appeared worldwide, aiming at retarding or even stopping and reversing the effects of aging on the human body. One of the cornerstones of anti-aging is hormone replacement. At present, women live one third of their lives in a state of sex-hormone deficiency. Men are also subject to age-related testosterone decline, but andropause remains frequently under-diagnosed and under-treated. Due to the decline of hormone production from gonads in both sexes, the importance of dehydroepiandrosterone (DHEA) in steroid hormone production increases with age. However, DHEA levels also decrease with age. Also, growth hormone age-associated decrease may be so important that insulin growth factor-1 levels found in elderly individuals are sometimes as low as those encountered in adult patients with established deficiency. Skin aging as well as decreases in lean body mass, bone mineral density, sexual desire and erectile function, intellectual activity and mood have all been related to this decrease of hormone production with age. Great disparities exist between recommendations from scientific societies and actual use of hormone supplements in aging and elderly patients. In this article, we review actual data on the effects of age related hormone decline on the aging process and age-related diseases such as sarcopenia and falls, osteoporosis, cognitive decline, mood disorders, cardiovascular health and sexual activity. We also provide information on the efficiency and safety of hormone replacement protocols in aging patients. Finally, we argue on future perspectives of such protocols as part of everyday practice.

Measurement of androgen and estrogen concentrations in cord blood: accuracy, biological interpretation, and applications to understanding human behavioral development

Accurately measuring hormone exposure during prenatal life presents a methodological challenge and there is currently no "gold standard" approach. Ideally, circulating fetal hormone levels would be measured at repeated time points during pregnancy. However, it is not currently possible to obtain fetal blood samples without significant risk to the fetus, and therefore surrogate markers of fetal hormone levels must be utilized. Umbilical cord blood can be readily obtained at birth and largely reflects fetal circulation in late gestation. This review examines the accuracy and biological interpretation of the measurement of androgens and estrogens in cord blood. The use of cord blood hormones to understand and investigate human development is then discussed.

Hyperandrogenemia predicts metabolic phenotype in polycystic ovary syndrome: the utility of serum androstenedione

CONTEXT

Polycystic ovary syndrome (PCOS) is a triad of anovulation, insulin resistance, and hyperandrogenism. Androgen excess may correlate with metabolic risk and PCOS consensus criteria define androgen excess on the basis of serum T. Here we studied the utility of the androgen precursor serum androstenedione (A) in conjunction with serum T for predicting metabolic dysfunction in PCOS.

PATIENTS AND METHODS

Eighty-six PCOS patients fulfilling Rotterdam diagnostic consensus criteria and 43 age- and body mass index-matched controls underwent measurement of serum androgens by tandem mass spectrometry and an oral glucose tolerance test with homeostatic model assessment of insulin resistance and insulin sensitivity index calculation. We analyzed 24-hour urine androgen excretion by gas chromatography/mass spectrometry.

RESULTS

PCOS patients had higher levels of serum androgens and urinary androgen metabolites than controls (all P < .001). Within the PCOS cohort, both serum A and T were positively correlated with the free androgen index (T × 100/SHBG) and total androgen metabolite excretion (all P < .001). All subjects with T above the normal reference range [high T (HT)] also had high A (HA/HT group, n = 56). However, the remaining 30 patients had normal T levels, either in the presence of HA (HA/NT; n = 20) or normal A (NA/NT; n = 10). The groups did not differ in age or BMI. The HA/HT and HA/NT groups had higher total androgen excretion than NA/NT (P < .01 and P < .05, respectively). Multiple linear regression showed a strong negative association between serum androstenedione and insulin sensitivity. The incidence of dysglycemia according to an oral glucose tolerance test increased with the severity of androgen phenotype (NA/NT, 0%; HA/NT, 14%; HA/HT, 25%, P = .03).

CONCLUSION

Simultaneous measurement of serum T and A represents a useful tool for predicting metabolic risk in PCOS women. HA levels are a sensitive indicator of PCOS-related androgen excess.

Genome-wide association study of sex hormones, gonadotropins and sex hormone-binding protein in Chinese men

BACKGROUND

Sex hormones and gonadotropins exert a wide variety of effects in physiological and pathological processes. Accumulated evidence shows a strong heritable component of circulating concentrations of these hormones. Recently, several genome-wide association studies (GWASs) conducted in Caucasians have identified multiple loci that influence serum levels of sex hormones. However, the genetic determinants remain unknown in Chinese populations. In this study, we aimed to identify genetic variants associated with major sex hormones, gonadotropins, including testosterone, oestradiol, follicle-stimulating hormone (FSH), luteinising hormone (LH) and sex hormone binding globulin (SHBG) in a Chinese population.

METHODS

A two-stage GWAS was conducted in a total of 3495 healthy Chinese men (1999 subjects in the GWAS discovery stage and 1496 in the confirmation stage).

RESULTS

We identified a novel genetic region at 15q21.2 (rs2414095 in CYP19A1), which was significantly associated with oestradiol and FSH in the Chinese population at a genome-wide significant level (p=6.54×10(-31) and 1.59×10(-16), respectively). Another single nucleotide polymorphism in CYP19A1 gene was significantly associated with oestradiol level (rs2445762, p=7.75×10(-28)). In addition, we confirmed the previous GWAS-identified locus at 17p13.1 for testosterone (rs2075230, p=1.13×10(-8)) and SHBG level (rs2075230, p=4.75×10(-19)) in the Chinese population.

CONCLUSIONS

This study is the first GWAS investigation of genetic determinants of FSH and LH. The identification of novel susceptibility loci may provide more biological implications for the synthesis and metabolism of these hormones. More importantly, the confirmation of the genetic loci for testosterone and SHBG suggests common genetic components shared among different ethnicities.

Reproductive aging in men

Aging in men is associated with a decrease in serum testosterone levels due to attrition in testicular Leydig cells and slowing of the hypothalamic GnRH pulse generator. The practicing endocrinologist is frequently consulted for consideration of testosterone therapy in older men with late-onset hypogonadism (LOH), a condition that many clinicians fail to distinguish from organic hypogonadism. Recent data using syndromic definition show that only 2% of 40-80-year-old men have LOH. Co-morbidities and obesity strongly contribute to LOH, suggesting that testosterone is a biomarker of health. Hence, prevention and treatment of these co-morbidities might attenuate age-related decline in androgen levels.

The impact of obesity on male reproduction: its biological significance

Since obesity and male subfertility have increased in parallel during the last decades, the hypothesis of an association between these two phenomena has been explored by several researchers. Although there is no consensus apparently obesity impacts men's reproductive potential by several mechanisms, like alterations on the hypothalamus-pituitary-testicular axis, modifications of spermatogenesis and semen quality and/or impairment of men's sexual health. This review intends to summarize the underlying bases of such alterations and propose new ones, without miscalculating their biological significance. Obesity is not rigorously related to subfertility; in addition, the existence of a genetic predisposition to obesity-linked sterility is currently under investigation. Nonetheless, the impact of obesity on male reproductive potential must be fully elucidated since the prevalence of obesity is increasing and consequently, the number of obese men with reduced fertility will also rise.

Comparative determinations of non SHBG-bound serum testosterone, using ammonium sulfate precipitation, Concanavalin A binding or calculation in men

BACKGROUND

Testosterone (T) circulates tightly bound to sex hormone-binding globulin (SHBG) and weakly to albumin. Non-SHBG-bound T is considered as the bioavailable T (BT) and was recommended for the evaluation of androgen disorders. Two methods, BT calculating from T, SHBG and albumin or BT measurement using ammonium sulfate precipitation of [SHBG-T] complex have been widely used. Using SHBG separation with Concanavalin-A (ConA) was recently proposed as a more specific method. The aim of this work was to compare these three methods in male patients.

METHODS

Serum samples of 131 consecutive untreated men (15-81 years) referred for suspicion of hypogonadism were collected. Total T was measured by GC-MS, SHBG by immunoradiometric assay. Level of BT was assayed using ammonium sulfate precipitation, ConA separation and calculated using the Issam web calculator.

RESULTS

Only few differences were found between ammonium sulfate or ConA BT measurements. However, we found much higher serum calculated BT than assayed BT with an increasing bias when BT levels increased.

CONCLUSIONS

Measurement of BT using ConA separation could be recommended. The results are equivalent to those obtained using ammonium sulfate precipitation. This method eliminates the possible non specific albumin precipitation that can occur with ammonium sulfate when the assay conditions are not rigorously controlled.

Selective cleavage of human sex hormone-binding globulin by kallikrein-related peptidases and effects on androgen action in LNCaP prostate cancer cells

Stimulation of the androgen receptor via bioavailable androgens, including testosterone and testosterone metabolites, is a key driver of prostate development and the early stages of prostate cancer. Androgens are hydrophobic and as such require carrier proteins, including sex hormone-binding globulin (SHBG), to enable efficient distribution from sites of biosynthesis to target tissues. The similarly hydrophobic corticosteroids also require a carrier protein whose affinity for steroid is modulated by proteolysis. However, proteolytic mechanisms regulating the SHBG/androgen complex have not been reported. Here, we show that the cancer-associated serine proteases, kallikrein-related peptidase (KLK)4 and KLK14, bind strongly to SHBG in glutathione S-transferase interaction analyses. Further, we demonstrate that active KLK4 and KLK14 cleave human SHBG at unique sites and in an androgen-dependent manner. KLK4 separated androgen-free SHBG into its two laminin G-like (LG) domains that were subsequently proteolytically stable even after prolonged digestion, whereas a catalytically equivalent amount of KLK14 reduced SHBG to small peptide fragments over the same period. Conversely, proteolysis of 5α-dihydrotestosterone (DHT)-bound SHBG was similar for both KLKs and left the steroid binding LG4 domain intact. Characterization of this proteolysis fragment by [(3)H]-labeled DHT binding assays revealed that it retained identical affinity for androgen compared with full-length SHBG (dissociation constant = 1.92 nM). Consistent with this, both full-length SHBG and SHBG-LG4 significantly increased DHT-mediated transcriptional activity of the androgen receptor compared with DHT delivered without carrier protein. Collectively, these data provide the first evidence that SHBG is a target for proteolysis and demonstrate that a stable fragment derived from proteolysis of steroid-bound SHBG retains binding function in vitro.

Sex differences in primary hypertension

Men have higher blood pressure than women through much of life regardless of race and ethnicity. This is a robust and highly conserved sex difference that it is also observed across species including dogs, rats, mice and chickens and it is found in induced, genetic and transgenic animal models of hypertension. Not only do the differences between the ovarian and testicular hormonal milieu contribute to this sexual dimorphism in blood pressure, the sex chromosomes also play a role in and of themselves. This review primarily focuses on epidemiological studies of blood pressure in men and women and experimental models of hypertension in both sexes. Gaps in current knowledge regarding what underlie male-female differences in blood pressure control are discussed. Elucidating the mechanisms underlying sex differences in hypertension may lead to the development of anti-hypertensives tailored to one's sex and ultimately to improved therapeutic strategies for treating this disease and preventing its devastating consequences.

Androgens and adipose tissue in males: a complex and reciprocal interplay

Clinical evidence shows that in males obesity is frequently associated with hypogonadism and vice versa; also, low testosterone levels have been considered a "hallmark" of metabolic syndrome in men. These observations indicate that there is a strict connection between anatomically and functionally distinct cell types such as white adipocytes and Leydig cells, that synthesize testosterone. Adipose tissue is able to control several functions of the testis through its products secreted in the bloodstream. On the other hand, circulating levels of testosterone and estradiol deeply affect adipocyte proliferation, differentiation, and fat mass distribution, hereby controlling critical metabolic functions, such as food intake, insulin sensitivity, vascular reactivity, and immunity. This paper highlights the existing clinical and experimental evidence linking androgens and adipose tissue and illustrates the consequences occurring when the balance between fat mass distribution and eugonadism is lost.

Sex differences on the judgment of line orientation task: a function of landmark presence and hormonal status

It has been well-established that men outperform women on some spatial tasks. The tools commonly used to demonstrate this difference (e.g. The Mental Rotations Task) typically involve problems and solutions that are presented in a context devoid of referents. The study presented here assessed whether the addition of referents (or "landmarks") would attenuate the well-established sex difference on the judgment of line orientation task (JLOT). Three versions of the JLOT were presented in a within design. The first iteration contained the original JLOT (JLOT 1). JLOT 2 contained three "landmarks" or referents and JLOT 3 contained only one landmark. The sex difference on JLOT 1 was completely negated by the addition of three landmarks on JLOT 2 or the addition of one landmark on JLOT3. In addition, salivary testosterone was measured. In men, gains in performance on the JLOT due to the addition of landmarks were positively correlated with testosterone levels. This suggests that men with the highest testosterone levels benefited the most from the addition of landmarks. These data help to highlight different strategies used by men and women to solve spatial tasks.