The Roles of Androgens in Humans: Biology, Metabolic Regulation and Health

Androgens are an important and diverse group of steroid hormone molecular species. They play varied functional roles, such as the control of metabolic energy fate and partition, the maintenance of skeletal and body protein and integrity and the development of brain capabilities and behavioral setup (including those factors defining maleness). In addition, androgens are the precursors of estrogens, with which they share an extensive control of the reproductive mechanisms (in both sexes). In this review, the types of androgens, their functions and signaling are tabulated and described, including some less-known functions. The close interrelationship between corticosteroids and androgens is also analyzed, centered in the adrenal cortex, together with the main feedback control systems of the hypothalamic-hypophysis-gonads axis, and its modulation by the metabolic environment, sex, age and health. Testosterone (T) is singled out because of its high synthesis rate and turnover, but also because age-related hypogonadism is a key signal for the biologically planned early obsolescence of men, and the delayed onset of a faster rate of functional losses in women after menopause. The close collaboration of T with estradiol (E2) active in the maintenance of body metabolic systems is also presented Their parallel insufficiency has been directly related to the ravages of senescence and the metabolic syndrome constellation of disorders. The clinical use of T to correct hypoandrogenism helps maintain the functionality of core metabolism, limiting excess fat deposition, sarcopenia and cognoscitive frailty (part of these effects are due to the E2 generated from T). The effectiveness of using lipophilic T esters for T replacement treatments is analyzed in depth, and the main problems derived from their application are discussed.

Current use of testosterone therapy in LGBTQ populations

Testosterone therapy (TT) is a type of gender-affirming hormone therapy (GAHT) in lesbian, gay, bisexual, transgender, and genderqueer (LGBTQ) populations for gender dysphoria (GD), body uneasiness, and sexual dysfunction. The physical and physiological effects of TT vary widely depending on the dosing regimen and duration of treatment. An individualized approach prioritizing patient-specific desired effects in the context of pre-existing characteristics and health history is strongly recommended. Although TT is an effective treatment for many patients, there has been an increase in the illegitimate acquisition of TT in recent years. Non-judicious prescribing and lack of physician surveillance increases the risk of unintended side effects and potential serious health consequences.

A Novel Hypothesis: A Role for Follicle Stimulating Hormone in Abdominal Aortic Aneurysm Development in Postmenopausal Women

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta, which can potentially be fatal due to exsanguination following rupture. Although AAA is less prevalent in women, women with AAA have a more severe AAA progression compared to men as reflected by enhanced aneurysm growth rates and a higher rupture risk. Women are diagnosed with AAA at an older age than men, and in line with increased osteoporosis and cardiovascular events, the delayed AAA onset has been attributed to the reduction of the protective effect of oestrogens during the menopausal transition. However, new insights have shown that a high follicle stimulating hormone (FSH) level during menopause may also play a key role in those diseases. In this report we hypothesize that FSH may aggravate AAA development and progression in postmenopausal women via a direct and/or indirect role, promoting aorta pathology. Since FSH receptors (FSHR) are reported on many other cell types than granulosa cells in the ovaries, it is feasible that FSH stimulation of FSHR-bearing cells such as aortic endothelial cells or inflammatory cells, could promote AAA formation directly. Indirectly, AAA progression may be influenced by an FSH-mediated increase in osteoporosis, which is associated with aortic calcification. Also, an FSH-mediated decrease in cholesterol uptake by the liver and an increase in cholesterol biosynthesis will increase the cholesterol level in the circulation, and subsequently promote aortic atherosclerosis and inflammation. Lastly, FSH-induced adipogenesis may lead to obesity-mediated dysfunction of the microvasculature of the aorta and/or modulation of the periaortic adipose tissue. Thus the long term increased plasma FSH levels during the menopausal transition may contribute to enhanced AAA disease in menopausal women and could be a potential novel target for treatment to lower AAA-related events in women.

Role of hormones in hypoactive sexual desire disorder and current treatment

Over the decades, female sexual dysfunction (FSD) has grown to be an increasingly potential problem that complicates the quality of life among women. In the current review, FSD refers to recurrent and persistent problems with sexual orgasm, desire, or response. One of the most common subtypes of FSD that has evoked increased research interest in the scientific community is hyposexuality. Today, there is a consensus that hyposexuality is a multifactorial condition that manifests with reduced sexual desire resulting in significant interpersonal distress. The objective of the current review was to examine how hormonal profile triggers propagate hypoactive sexual desire disorder (HSDD), and to highlight effective treatment interventions that can be used to manage the condition. The current review describes HSDD as a sexual dysfunction characterized by the absence or lack of sexual desire and fantasies for sexual activities. The review argues that even if the role of sexual hormones is essential in modulating HSDD through therapeutic interventions, an effective comprehension of the biologic mechanisms underlying HSDD is necessary. There is a consensus in the literature that HSDD still poses significant challenges due to the lack of properly formulated treatment regimens and absence of clear clinical guidelines. That is, a better intervention consisting of both psycho-relational and biologic aspects is compulsory if tailored management and accurate diagnosis of HSDD in clinical practice are to be realised. The review concludes that, to date, a reliable clinical intervention to manage hyposexuality is still absent and more interventions, in terms of safety and efficacy, are required. Thus, additional investigation is required to document precise hormonal or non-hormonal pharmacotherapeutic agents for individualised care among patients with HSDD.

Micturition dysfunction in four-month old ovariectomized rats: Effects of testosterone replacement

AIMS

Androgen deficiency has been implicated in urological complications of postmenopausal women. This study examined the effects of testosterone replacements on the lower urinary tract dysfunction in 4-month old ovariectomized (OVX) rats.

MAIN METHODS

Sprague-Dawley female rats were OVX bilaterally. Three months later, rats received single intramuscular injections of testosterone undecanoate. Cystometric study, and bladder and urethra smooth muscle reactivities were evaluated.

KEY FINDINGS

Ovariectomy reduced by 65% (p<0.05) the serum testosterone levels. Testosterone replacement at 5mg/kg restored serum hormone levels to baseline, whereas 10mg/kg produced 14-fold higher testosterone levels. OVX rats exhibited significant increases of body weight, perigonadal fat and blood pressure, and reduced uterus weight, but none of these parameters were changed by testosterone replacements. OVX rats exhibited micturition dysfunction characterized by increases of basal pressure, threshold pressure, voiding frequency and post-voiding pressure. In addition, the bladder contractions induced by electrical-field stimulation (EFS) and carbachol were significantly reduced, whereas angiotensin II-induced urethral contractions were significantly increased in OVX rats. Testosterone replacement at 10mg/kg (but not at 5mg/kg) dose fully normalized the in vivo micturition dysfunction, as well as the in vitro bladder and urethral alterations. Testosterone (10mg/kg) also significantly potentiated the bladder relaxations induced by the β₃-adrenoceptor agonist mirabegron. The protective effects of testosterone were not modified by concomitant treatment with the aromatase inhibitor letrozole (2.5mg/kg, 4weeks).

SIGNIFICANCE

The improvement of micturition dysfunction by testosterone replacement suggests that androgen therapy might be of therapeutic benefit for urological complications associated with post-menopause.

An update on sexual function and dysfunction in women

Sexual function of women can be affected by many factors resulting in female sexual dysfunction (FSD). Sexual dysfunction is a common problem among women of all ages and has negative effects not only on their quality of lives but also on the sexual function and quality of life of their partners. It can also affect mental health of the entire family and society. Regarding the multidimensional nature of female sexual dysfunction and considering its consequences, this condition needs to be recognised in its early stages in order to prevent future consequences and impacts. This article discusses biopsychosocial aspect of female sexual function, classifications and risk factors of female sexual dysfunction and investigates current approaches to identify and treat this problem.

The safety of testosterone therapy in women

Hypoactive sexual desire disorder (HSDD), a subset of female sexual dysfunction, causes personal distress for surgically and naturally postmenopausal and premenopausal women. HSDD has a multi-factorial etiology, including psychosocial factors such as relationship issues and medical factors such as medications, chronic illnesses, and hormonal effects. Although no androgen therapies for female sexual dysfunction are currently approved for use in Canada, clinical trials support the efficacy and short-term safety of testosterone therapy for HSDD. We review the scientific evidence for the safety of testosterone therapy for HSDD.

Oral low-dose testosterone administration induces whole-body protein anabolism in postmenopausal women: a novel liver-targeted therapy

OBJECTIVE

In hypopituitary men, oral delivery of unesterified testosterone in doses that result in a solely hepatic androgen effect enhances protein anabolism during GH treatment. In this study, we aimed to determine whether liver-targeted androgen supplementation induces protein anabolism in GH-replete normal women.

DESIGN

Eight healthy postmenopausal women received 2-week treatment with oral testosterone at a dose of 40 mg/day (crystalline testosterone USP). This dose increases portal concentrations of testosterone, exerting androgenic effects on the liver without a spillover into the systemic circulation.

OUTCOME MEASURES

The outcome measures were whole-body leucine turnover, from which leucine rate of appearance (LRa, an index of protein breakdown) and leucine oxidation (Lox, a measure of irreversible protein loss) were estimated, energy expenditure and substrate utilization. We measured the concentration of liver transaminases as well as of testosterone, SHBG and IGF1.

RESULTS

Testosterone treatment significantly reduced LRa by 7.1 ± 2.5% and Lox by 14.6 ± 4.5% (P<0.05). The concentration of liver transaminases did not change significantly, while that of serum SHBG fell within the normal range by 16.8 ± 4.0% and that of IGF1 increased by 18.4 ± 7.7% (P<0.05). The concentration of peripheral testosterone increased from 0.4 ± 0.1 to 1.1 ± 0.2 nmol/l (P<0.05), without exceeding the upper normal limit. There was no change in energy expenditure and fat and carbohydrate utilization.

CONCLUSIONS

Hepatic exposure to unesterified testosterone by oral delivery stimulates protein anabolism by reducing protein breakdown and oxidation without inducing systemic androgen excess in women. We conclude that a small oral dose of unesterified testosterone holds promise as a simple novel treatment of protein catabolism and muscle wasting.

Androgens and breast cancer risk

Transdermal testosterone supplementation is a treatment option for postmenopausal women with distressful decreased libido. Side effects are minor, but there is a long-term safety concern with respect to breast cancer, as women with high testosterone serum levels appear to be at a significantly increased risk to have or to develop breast cancer within a few years. Epidemiological studies of sufficient duration to study long-term effects of testosterone supplementation are limited, both in number and in methodological quality and are, therefore, inconclusive. Preclinical studies do not provide evidence for an androgen receptor-mediated stimulating effect of androgens on breast epithelium. However, one biologically plausible possibility, which cannot be ruled out, is that exogenous androgens become mitogenic after aromatization into bioactive oestradiol, either in peripheral fat or within the breast or even within small occult tumours. The evidence available so far makes counselling women interested in testosterone supplementation for distressful low sexual desire, more of an art than science.

The testosterone metabolite 3α-diol enhances female rat sexual motivation when infused in the nucleus accumbens shell

AIM

The purpose of this study was to provide a quantitative assessment of female rat sexual behaviors after acute exposure to the A-ring reduced testosterone metabolite, androstanediol (3α-Diol), through the nucleus accumbens (NA) shell.

MAIN OUTCOME MEASURES

Quantitative analyses of female rat sexual behaviors and assessment of protein levels for the enzyme glutamic acid decarboxylase isoform 67 (GAD67) and gephyrin, a protein that participates in the clustering of GABA-A receptors in postsynaptic cells, were accomplished.

METHODS

Female rats were ovariectomized and primed with estrogen and progesterone to induce sexual behaviors. Females received a 3α-Diol infusion via guided cannula that aimed to the NA shell five minutes prior to a sexual encounter with a stud male. The following parameters were videotaped and measured in a frame by frame analysis: lordosis quotient (LQ), Lordosis rating (LR), frequency and duration of proceptive behaviors (hopping/darting and ear wiggling). Levels of GAD67 and gephyrin were obtained by Western blot analysis two or twenty-four hours after the sexual encounter.

RESULTS

Acute exposure to 3α-Diol in the NA shell enhanced LR, ear wiggling, and hopping/darting but not LQ. Some of these behavioral effects were counteracted by co-infusion of 3α-Diol plus the GABAA-receptor antagonist GABAzine. A transient reduction of GAD67 levels in the NA shell was detected.

CONCLUSIONS

The testosterone metabolite 3α-Diol enhances sexual proceptivity, but not receptivity, when infused into the NA shell directly. The GABAergic system may participate in the androgen-mediated enhancement of female rat sexual motivation.

Menopause and sexual desire: the role of testosterone

The present short review underlines the role of testosterone (T) in the motivational and satisfaction components of women's sexuality and critically discusses the strategies to treat hypoactive sexual desire disorder (HSDD), a condition of low desire associated with personal and/or interpersonal difficulties, which is more common in surgical menopausal women. There are multiple ways androgens target the brain regions (hypothalamic, limbic and cortical) involved in sexual function and behaviour. Even though circulating available androgens have been implicated in several domains of sexual response, they seem to be related weakly to symptoms, such as low sexual desire, poor sexual arousal, orgasm and diminished well-being in postmenopausal women. The possibilities of treating low sexual desire/HSDD are multifaceted and should include the combination of pharmacological treatments able to maximize biological signals driving the sexual response, and individualized psychosocial therapies in order to overcome personal and relational difficulties. Transdermal T has been shown to be effective at a dose of 300 µg/day both in surgically and naturally menopausal women replaced with estrogen or not, without any relevant side-effects. However, the decision to treat postmenopausal women with HSDD with T is mainly based on clinical judgement, after informed consent regarding the unknown long-term risks.

Management of hypoactive sexual desire disorder in women: current and emerging therapies

Hypoactive sexual desire disorder (HSDD) is a common multifactorial condition which is characterized by a decrease in sexual desire that causes marked personal distress and/or interpersonal difficulty. The general idea that HSDD is a sexual dysfunction difficult to treat is due to the large number of potential causes and contributing factors. Indeed, a balanced approach comprising both biological and psycho-relational factors is mandatory for accurate diagnosis and tailored management in clinical practice. There are currently no approved pharmacological treatments for premenopausal women with HSDD, while transdermal testosterone is approved in Europe for postmenopausal women who experience HSDD as a result of a bilateral oophorectomy. Even though the role of sex hormones in modulating the sexual response during the entire reproductive life span of women is crucial, a better understanding of the neurobiological basis of sexual desire supports the idea that selective psychoactive agents may be proposed as nonhormonal treatments to restore the balance between excitatory and inhibitory stimuli leading to a normal sexual response cycle. We conclude that the ideal clinical approach to HSDD remains to be established in term of efficacy and safety, and further research is needed to develop specific hormonal and nonhormonal pharmacotherapies for individualized care in women.

The impairment of sexual function is less distressing for menopausal than for premenopausal women

INTRODUCTION

Menopause requires psychological and physical adjustments because of the occurring significant hormonal changes. Sexuality is one of the aspects that undergoes the most profound modifications. Preliminary data suggest that sometimes women do not regard sexual changes as problematic and often readjust their life and relationship according to their new physical status.

AIM

The aim of our study was to evaluate sexual function and the way women feel by comparing healthy postmenopausal and premenopausal women.

METHODS

One hundred menopausal (M) and 100 premenopausal (pM) healthy women were asked to complete anonymous questionnaires to assess sexual function and stress related to sexual activity.

MAIN OUTCOME MEASURES

Female Sexual Function Index (FSFI), Female Sexual Distress Scale (FSDS) were completed by M and pM women. Results. Medium FSFI score was 20.5 +/- 9.6 and 26.4 +/- 7.7 (P < 0.0005) and medium FSDS score was 12.1 +/- 11.7 (95% CI 9.7-14.4) and 11.3 +/- 10.2 (P = 0.917) for M and pM women, respectively. Twenty-five of the 69 M women and 20 of the 31 pM women with a pathological score in the FSFI questionnaire scored higher than 15 in the FSDS (P < 0.0005). The overall prevalence of sexual dysfunction was 20% and 25% (P = 0.5) in the M and pM women.

CONCLUSIONS

Our data confirm that menopause is associated with changes in sexual function that may be compatible with sexual dysfunction. However, personal distress caused by these changes in sexual life appears to be lower among menopausal women (36.2%) as compared with premenopausal women (64.5%). These data suggest that medical treatment for sexual health in menopause must be highly personalized and carefully prescribed.

Effect of testosterone on E1S-sulfatase activity in non-malignant and cancerous breast cells in vitro

INTRODUCTION

Testosterone (T) is a therapeutic option for women with hypoactive sexual desire disorder. T may have an impact on the mammary gland by altering local estrogen synthesis. The aim of the present study was to measure the effect of T on estrone-sulfate (E1S)-sulfatase (STS) expression, and activity using hormone-dependent BC cells with high and low aggressive potential (BT-474, MCF-7), and HBL-100 as a breast cell line of non-malignant origin.

METHODS

Cells were incubated in RPMI 1640 medium containing 5% steroid-depleted fetal calf serum for 3d, and subsequently incubated in absence or presence of T alone, and combined with anastrozole (A) at 10(-8)M, and 10(-6)M at 37 degrees C for either 24h or directly in cell extracts ("direct"). STS protein expression was measured by dot-blot (immunoblotting), and STS, HSD17B1 and HSD17B2 mRNA levels by quantitative RT-PCR. STS activity was evaluated by incubating homogenized breast cells with [(3)H]-E1S and separating the products E1, and E2 by thin layer chromatography.

RESULTS

Basal STS mRNA expression did not reveal group differences. However, STS mRNA was decreased by T+A in MCF-7 cells. 17HSDB1 expression was decreased by T+A in BT-474 cells, and 17HSDB2 expression was decreased by A and T+A treatment in MCF-7 cells. Basal and T treated STS protein expression was significantly higher in malignant compared to non-malignant breast cells. However, T did not induce significant intra-cell line differences. Similarly, basal and T treated STS activity was significantly higher in highly malignant compared to non-malignant breast cells. Regardless of cell lines, T slightly decreased STS activity after "direct" incubation, but led to an increase of local estrogen formation after 24h which was attenuated, and partly reversed by A, respectively.

CONCLUSIONS

The more aggressive the breast cell line, the higher the local estrogen formation. The transition from normal to malignant seems to be accompanied by an altered autoregulation. The given local endocrine milieu seems to be essential for response to T.

Testosterone reduces cumulative burying in female Wistar rats with minimal participation of estradiol

Testosterone exerts anxiolytic effects, but the participation of its aromatase metabolic product estradiol is controversial. Therefore, we used the defensive burying paradigm in female Wistar rats to explore testosterone's (1.0 mg/rat, s.c.) interactions with picrotoxin (a noncompetitive gamma-aminobutyric acid-A receptor [GABA(A)] antagonist; 1.0 mg/kg, i.p.), formestane (an aromatase inhibitor; 3.0 mg/rat, s.c.), and tamoxifen (an estrogen receptor-beta antagonist; 1.0 mg/kg, s.c.). Serum levels of testosterone, estradiol, and progesterone were determined in the same rats. Burying latency and locomotion did not significantly change. Systemic testosterone administration enhanced serum testosterone and estradiol levels and reduced defensive burying. This reduction in total burying was blocked by pretreatment with picrotoxin and tamoxifen, but not formestane. We conclude that testosterone produced anxiolytic-like effects in female rats that were mediated by actions at the GABA(A) receptor, with participation of the estradiol receptor-beta, rather than estradiol aromatization.