Localization of the Androgen‐Synthesizing Enzymes, Androgen Receptor, and Sex Steroids in the Vagina: Possible Implications for the Treatment of Postmenopausal Sexual Dysfunction

Vestibular tissue changes following administration of intravaginal prasterone: a vulvoscopic open-label pilot study in menopausal women with dyspareunia

Background

Prasterone, an intravaginal dyspareunia treatment in menopausal women, improves vaginal health through intracellular conversion of dehydroepiandrosterone into androgens and estrogens. Phase 3 trials for prasterone showed significant improvement in vaginal tissue health and reduction of pain.

Aim

To assess vestibular changes with daily use of intravaginal prasterone in menopausal women with moderate to severe dyspareunia.

Methods

This open-label prospective pilot study was conducted over 20 weeks. It included 11 menopausal women (median age, 56 years) who were treated daily with intravaginal inserts of 6.5-mg prasterone and assessed monthly. During vulvoscopy, vestibular pain was assessed by cotton-tipped swab testing, and vestibular and vaginal health was independently assessed with the Visual Scale (VS). In addition, vulvoscopic photographs were obtained and assessed via the Vulvoscopic Genital Tissue Appearance (VGTA) scale to evaluate overall genital tissue health. Mean changes from baseline for genital tissue health and pain assessments were analyzed by repeated measures 1-way analysis of variance, followed by a Dunnett post hoc test. Sexual event diaries were completed and adverse events recorded.

Outcomes

Outcomes included indices of genital tissue health: pain assessment by cotton-tipped swab testing, VS of the vestibule and vagina, VGTA, and sexual event diary.

Results

Aggregate scores from the cotton-tipped swab test progressively improved, reaching statistical significance at week 16, which was maintained through week 20 (-7.27, P = .019). VS scores significantly improved from baseline by week 4 and were maintained through week 20 for the vestibule (-3.00, P = .004) and vagina (-4.00, P = .002). An overall 1607 vulvoscopic photographs were examined; all showed reduction in vestibular erythema and pallor at the end of the study. The mean change from baseline at week 20 for the VGTA score was -7.9 (P = .0016). Intercourse associated with pain was reduced from 81.3% of initiated events during the first month of the study to 8.3% during the last month. Sexual activities that were discontinued due to discomfort were reduced from 45.8% to 6.3%. No prasterone-related serious adverse events were reported.

Clinical Implications

Prasterone, a safe and effective intravaginal hormone treatment, significantly improves vestibular health parameters.

Strengths and Limitations

Strengths are the prospective study design and the use of multiple outcome measures to assess vestibular tissue health and pain associated with sexual activity. Limitations are the small study cohort and use of nonvalidated outcome measures.

Conclusion

Our findings suggest that intravaginal prasterone exerts biologic activity on the androgenic endodermal vestibule, as the medication passes from vagina to vestibule, resulting in amelioration of pain associated with sexual activity.

Revisiting the physiological role of androgens in women

INTRODUCTION

Extensive research underlines the critical functions of androgens in females. Nevertheless, the precise mechanisms of their action are poorly understood. Here, we review the existing literature regarding the physiological role of androgens in women throughout life.

AREAS COVERED

Several studies show that androgen receptors (ARs) are broadly expressed in numerous female tissues. They are essential for many physiological processes, including reproductive, sexual, cardiovascular, bone, muscle, and brain health. They are also involved in adipose tissue and liver function. Androgen levels change with the menstrual cycle and decrease in the first decades of life, independently of menopause.

EXPERT OPINION

To date, studies are limited by including small numbers of women, the difficulty of dosing androgens, and their cyclical variations. In particular, whether androgens play any significant role in regulating the establishment of pregnancy is poorly understood. The neural functions of ARs have also been investigated less thoroughly, although it is expressed at high levels in brain structures. Moreover, the mechanism underlying the decline of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) with age is unclear. Other factors, including estrogen's effect on adrenal androgen production, reciprocal regulation of ARs, and non-classical effects of androgens, remain to be determined.

Testosterone positively regulates vagina NO-induced relaxation: an experimental study in rats

PURPOSE

Female sexual response involves a complex interplay between neurophysiological mechanisms and the nitric oxide (NO)-mediated relaxation of clitoris and vagina. The aim of this study was to evaluate sex steroids regulation of the relaxant pathway in vagina, using a validated animal model.

METHODS

Subgroups of OVX Sprague-Dawley rats were treated with 17β-estradiol, testosterone, or testosterone and letrozole, and compared with a group of intact animals. Masson's trichrome staining was performed for morphological evaluation of the distal vaginal wall, in vitro contractility studies investigated the effect of OVX and in vivo treatments on vaginal smooth muscle activity. RNA from vaginal tissue was analyzed by semi-quantitative RT-PCR.

RESULTS

Immunohistochemical analysis showed that OVX induced epithelial and smooth muscle structural atrophy, testosterone and testo + letrozole increased the muscle bundles content and organization without affecting the epithelium while 17β-estradiol mediated the opposite effects. In vitro contractility studies were performed on noradrenaline pre-contracted vaginal strips from each experimental group. Acetylcholine (0.001-10 µM) stimulation induced a concentration-dependent relaxation, significantly reduced by NO-synthase inhibitor L-NAME and by guanylate cyclase inhibitor ODQ. OVX resulted in a decreased responsiveness to acetylcholine, restored by testosterone, with or without letrozole, but not by 17β-estradiol. OVX sensitivity to the NO-donor SNP was higher than in the control. Vardenafil, a PDE5 inhibitor, enhanced SNP effect in OVX + testosterone as well as in control, as supported by RNA expression analysis.

CONCLUSIONS

Our study demonstrates that testosterone improves the NO-mediated smooth muscle vaginal cells relaxation confirming its role in maintaining the integrity of muscular relaxant machinery.

The role of androgens in women's health and wellbeing

Androgens in women, as well as in men, are intrinsic to maintenance of (i) reproductive competency, (ii) cardiac health, (iii) appropriate bone remodeling and mass retention, (iii) muscle tone and mass, and (iv) brain function, in part, through their mitigation of neurodegenerative disease effects. In recognition of the pluripotency of endogenous androgens, exogenous androgens, and selected congeners, have been prescribed off-label for several decades to treat low libido and sexual dysfunction in menopausal women, as well as, to improve physical performance. However, long-term safety and efficacy of androgen administration has yet to be fully elucidated. Side effects often observed include (i) hirsutism, (ii) acne, (iii) deepening of the voice, and (iv) weight gain but are associated most frequently with supra-physiological doses. By contrast, short-term clinical trials suggest that the use of low-dose testosterone therapy in women appears to be effective, safe and economical. There are, however, few clinical studies, which have focused on effects of androgen therapy on pre- and post-menopausal women; moreover, androgen mechanisms of action have not yet been thoroughly explained in these subjects. This review considers clinical effects of androgens on women's health in order to prevent chronic diseases and reduce cancer risk in gynecological tissues.

Japanese eel retinol dehydrogenases 11/12-like are 17-ketosteroid reductases involved in sex steroid synthesis

The synthesis of 11-ketotestosterone (11KT) and estradiol-17β (E2), which play important roles in the regulation of gametogenesis in teleost fishes, is catalyzed by several steroidogenic enzymes. In particular, 17β-hydroxysteroid dehydrogenases (Hsd17bs) with 17-ketosteroid reducing activity (17KSR activity) are essential enzymes in the formation of these sex steroid hormones in the gonads and other tissues. Retinol dehydrogenase 11 (RDH11) has been suggested to be a novel tentative HSD17B (HSD17B15) in humans for a decade, however no definitive proof has been provided yet. In this study, three cDNAs related to human RDH11 were isolated from Japanese eel testis and characterized. Sequence similarity and phylogenetic analyses revealed their close relationship to human rdh11 and rdh12 gene products and they were designated as rdh11/12-like 1, rdh11/12-like 2, and rdh11/12-like 3. Three recombinant Rdh11/12-like proteins expressed in HEK293T cells catalyzed the transformation of estrone into E2 and androstenedione into testosterone. Only Rdh11/12-like 1 catalyzed the conversion of 11-ketoandrostenedione into 11KT. Tissue-distribution analysis by quantitative real-time polymerase chain reaction revealed, in immature male Japanese eel, that rdh11/12-like 1 and rdh11/12-like 2 are predominantly expressed in testis and brain, while rdh11/12-like 3 is expressed ubiquitously. Moreover, we analyzed the effects of gonadotropins and 11KT on the expression of the three rdh11/12-like mRNAs in the immature testis. In vitro incubation of immature testes with various doses of recombinant Japanese eel follicle stimulating hormone, luteinizing hormone, and 11KT indicated that the expression of rdh11/12-like 1 mRNA, rdh11/12-like 2, and rdh11/12-like 3 did not change. These findings suggest that the three Rdh11/12-like proteins metabolize sex steroids. Rdh11/12-like 1 may be one of the enzymes with 17KSR activity involved in the production of 11KT in the testis.

International Society for the Study of Women's Sexual Health Clinical Practice Guideline for the Use of Systemic Testosterone for Hypoactive Sexual Desire Disorder in Women

AIM

To provide a clinical practice guideline for the use of testosterone including identification of patients, laboratory testing, dosing, post-treatment monitoring, and follow-up care in women with hypoactive sexual desire disorder (HSDD).

METHODS

The International Society for the Study of Women's Sexual Health appointed a multidisciplinary panel of experts who performed a literature review of original research, meta-analyses, review papers, and consensus guidelines regarding testosterone use in women. Consensus was reached using a modified Delphi method.

OUTCOMES

A clinically useful guideline following a biopsychosocial assessment and treatment approach for the safe and efficacious use of testosterone in women with HSDD was developed including measurement, indications, formulations, prescribing, dosing, monitoring, and follow-up.

RESULTS

Although the Global Position Statement endorses testosterone therapy for only postmenopausal women, limited data also support the use in late reproductive age premenopausal women, consistent with the International Society for the Study of Women's Sexual Health Process of Care for the Management of HSDD. Systemic transdermal testosterone is recommended for women with HSDD not primarily related to modifiable factors or comorbidities such as relationship or mental health problems. Current available research supports a moderate therapeutic benefit. Safety data show no serious adverse events with physiologic testosterone use, but long-term safety has not been established. Before initiation of therapy, clinicians should provide an informed consent. Shared decision-making involves a comprehensive discussion of off-label use, as well as benefits and risks. A total testosterone level should not be used to diagnose HSDD, but as a baseline for monitoring. Government-approved transdermal male formulations can be used cautiously with dosing appropriate for women. Patients should be assessed for signs of androgen excess and total testosterone levels monitored to maintain concentrations in the physiologic premenopausal range. Compounded products cannot be recommended because of the lack of efficacy and safety data.

CLINICAL IMPLICATIONS

This clinical practice guideline provides standards for safely prescribing testosterone to women with HSDD, including identification of appropriate patients, dosing, and monitoring.

STRENGTHS AND LIMITATIONS

This evidence-based guideline builds on a recently published comprehensive meta-analysis and the Global Position Statement endorsed by numerous societies. The limitation is that testosterone therapy is not approved for women by most regulatory agencies, thereby making prescribing and proper dosing challenging.

CONCLUSION

Despite substantial evidence regarding safety, efficacy, and clinical use, access to testosterone therapy for the treatment of HSDD in women remains a significant unmet need.

International Society for the Study of Women's Sexual Health Clinical Practice Guideline for the Use of Systemic Testosterone for Hypoactive Sexual Desire Disorder in Women

Background: The Global Consensus Position Statement on the Use of Testosterone Therapy for Women (Global Position Statement) recommended testosterone therapy for postmenopausal women with hypoactive sexual desire disorder (HSDD).

Aim: To provide a clinical practice guideline for the use of testosterone including identification of patients, laboratory testing, dosing, post-treatment monitoring, and follow-up care in women with HSDD.

Methods: The International Society for the Study of Women's Sexual Health appointed a multidisciplinary panel of experts who performed a literature review of original research, meta-analyses, review papers, and consensus guidelines regarding testosterone use in women. Consensus was reached using a modified Delphi method.

Outcomes: A clinically useful guideline following a biopsychosocial assessment and treatment approach for the safe and efficacious use of testosterone in women with HSDD was developed including measurement, indications, formulations, prescribing, dosing, monitoring, and follow-up.

Results: Although the Global Position Statement endorses testosterone therapy for only postmenopausal women, limited data also support the use in late reproductive age premenopausal women, consistent with the International Society for the Study of Women's Sexual Health Process of Care for the Management of HSDD. Systemic transdermal testosterone is recommended for women with HSDD not primarily related to modifiable factors or comorbidities such as relationship or mental health problems. Current available research supports a moderate therapeutic benefit. Safety data show no serious adverse events with physiologic testosterone use, but long-term safety has not been established. Before initiation of therapy, clinicians should provide an informed consent. Shared decision-making involves a comprehensive discussion of off-label use, as well as benefits and risks. A total testosterone level should not be used to diagnose HSDD, but as a baseline for monitoring. Government-approved transdermal male formulations can be used cautiously with dosing appropriate for women. Patients should be assessed for signs of androgen excess and total testosterone levels monitored to maintain concentrations in the physiologic premenopausal range. Compounded products cannot be recommended because of the lack of efficacy and safety data.

Clinical Implications: This clinical practice guideline provides standards for safely prescribing testosterone to women with HSDD, including identification of appropriate patients, dosing, and monitoring.

Strengths & Limitations: This evidence-based guideline builds on a recently published comprehensive meta-analysis and the Global Position Statement endorsed by numerous societies. The limitation is that testosterone therapy is not approved for women by most regulatory agencies, thereby making prescribing and proper dosing challenging.

Conclusion: Despite substantial evidence regarding safety, efficacy, and clinical use, access to testosterone therapy for the treatment of HSDD in women remains a significant unmet need.

Insight on the Intracrinology of Menopause: Androgen Production within the Human Vagina

In this study, we investigated steroidogenic gene mRNA expression in human vaginas and verified the ability of human vagina smooth muscle cells (hvSMCs) to synthesize androgens from upstream precursor dehydroepiandrosterone (DHEA). As a readout for androgen receptor (AR) activation, we evaluated the mRNA expression of various androgen-dependent markers. hvSMCs were isolated from vagina tissues of women undergoing surgery for benign gynecological diseases. In these cells, we evaluated mRNA expression of several steroidogenic enzymes and sex steroid receptors using real time reverse transcription-polymerase chain reaction. Androgen production was quantified with liquid chromatography tandem-mass spectrometry (LC-MS/MS). In vaginal tissues, AR mRNA was significantly less expressed than estrogen receptor α, whereas in hvSMCs, its mRNA expression was higher than progestin and both estrogen receptors. In hvSMCs and in vaginal tissue, when compared to ovaries, the mRNA expression of proandrogenic steroidogenic enzymes (HSD3β1/β2, HSD17β3/β5), along with 5α-reductase isoforms and sulfotransferase, resulted as being more abundant. In addition, enzymes involved in androgen inactivation were less expressed than in the ovaries. The LC-MS/MS analysis revealed that, in hvSMCs, short-term DHEA supplementation increased Δ4-androstenedione levels in spent medium, while increasing testosterone and DHT secretion after longer incubation. Finally, androgenic signaling activation was evaluated through AR-dependent marker mRNA expression, after DHEA and T stimulation. This study confirmed that the human vagina is an androgen-target organ with the ability to synthesize androgens, thus providing support for the use of androgens for local symptoms of genitourinary syndrome in menopause.

The role of androgens in the treatment of genitourinary syndrome of menopause (GSM): International Society for the Study of Women's Sexual Health (ISSWSH) expert consensus panel review

OBJECTIVE

The objective of this consensus document is to broaden the perspective on clinical management of genitourinary syndrome of menopause to include androgens.

METHODS

A modified Delphi method was used to reach consensus among the 14 international panelists representing multiple disciplines and societies.

RESULTS

Menopause-related genitourinary symptoms affect over 50% of midlife and older women. These symptoms have a marked impact on sexual functioning, daily activities, emotional well-being, body image, and interpersonal relations. Tissues in the genitourinary system are both androgen and estrogen-dependent. The clitoris, vestibule, including minor and major vestibular glands, urethra, anterior vaginal wall, periurethral tissue, and pelvic floor are androgen-responsive. Historically, treatment of postmenopausal genitourinary symptoms involved both androgens and estrogens. This subsequently gave rise to predominantly estrogen-based therapies. More recently, double-blind, placebo-controlled clinical trials have demonstrated that local vaginal dehydroepiandrosterone improves symptoms in postmenopausal women, including moderate to severe dyspareunia. Limited data suggest that systemic testosterone treatment may improve vaginal epithelial health and blood flow. Open-label studies that have used high doses of intravaginal testosterone in the presence of aromatase inhibitor therapy for breast cancer have resulted in supraphysiological serum testosterone levels, and have been reported to lower vaginal pH, improve the vaginal maturation index, and reduce dyspareunia.

CONCLUSIONS

Vaginal dehydroepiandrosterone, hypothesized to enhance local production of both androgen and estrogen, is effective for the management of dyspareunia in menopause. Vaginal testosterone offers potential as a treatment for genitourinary syndrome of menopause, but more studies are needed.

Therapies for the management of genitourinary syndrome of menopause

Introduction

The genitourinary syndrome of menopause is a new term that describes various menopausal symptoms and signs including not only genital symptoms (dryness, burning, and irritation) and sexual symptoms (lack of lubrication, discomfort or pain, and impaired function), but also urinary symptoms (urgency, dysuria, and recurrent urinary tract infections).

Methods

We conducted a systematic scoping review of data in women therapies with genitourinary syndrome of menopause or vulvovaginal atrophy in peer-reviewed, English-language publications in the last 20 years.

Results

The terms vulvovaginal atrophy and atrophic vaginitis, which were generally used up until recently, had a limitation because they did not cover the full spectrum of symptoms and did not imply that the symptoms are related to a decreased sex steroid level in menopause. The concept of genitourinary syndrome of menopause was recently introduced and has been gaining widespread use. Since genitourinary syndrome of menopause may have a profound negative impact on the quality of life of postmenopausal women, patients should be made aware of these problems and treated with an appropriate effective therapy. Therefore, in this review we introduce therapies for this syndrome, both local and systemic, and discuss the importance of genitourinary syndrome of menopause comprehension and the need to have an active treatment of this syndrome in postmenopausal women.

Conclusion

The increasing number of therapies for menopausal symptoms opens up new options. In addition, new products have been designed and developed by pharmaceutical companies as new possibilities for patients who did not have any treatment available and also to improve compliance.

Treatment of moderate to severe dyspareunia with intravaginal prasterone therapy: a review

The loss of sex steroids (e.g. estradiol, dehydroepiandrosterone [DHEA], progesterone) that causes menopause commonly affects a woman's general health and produces bothersome physical changes that may interfere with normal sexual and genitourinary functioning. Although both over-the-counter and prescription treatments are available, there remains a large unmet need, as less than 10% of women are treated. Adrenal DHEA and its sulfate are the most abundant steroids in humans. Here we review the development of intravaginal prasterone, the synthetic equivalent to endogenous DHEA. Prasterone is approved by the US Food and Drug Administration for the treatment of moderate to severe dyspareunia, a symptom of vulvar and vaginal atrophy, due to menopause. Prasterone has been shown to decrease the pain associated with dyspareunia, and to improve vaginal pH, as well as superficial and parabasal cell counts, while maintaining serum hormone levels within the range of those seen in normal postmenopausal women. Unlike other menopausal prescription therapies, intravaginal prasterone does not carry a boxed warning, thus allowing the clinician and patient to engage in meaningful and reassuring discussion around a new approach that treats this common, debilitating condition.

Immunolocalization of steroidogenic enzymes in the vaginal mucous of Galea spixii during the estrous cycle

BACKGROUND

The synthesis of sex steroids is controlled by several enzymes such as17α-hydroxylase cytochrome P450 (P450c17) catalyzing androgen synthesis and aromatase cytochrome P450 (P450arom) catalyzing estrogen synthesis, both of which must complex with the redox partner NADPH-cytochrome P450 oxidoreductase (CPR) for activity. Previous studies have identified expression of steroidogenic enzymes in vaginal tissue, suggesting local sex steroid synthesis. The current studies investigate P450c17, P450aromatase and CPR expression in vaginal mucosa of Galea spixii (Spix cavy) by immuno-histochemical and western immunoblot analyses.

METHODS

Stages of estrous cyclicity were monitored by vaginal exfoliative cytology. After euthanasia, vaginal tissues were retrieved, fixed and frozen at diestrus, proestrus, estrus and metestrus. The ovaries and testis were used as positive control tissues for immunohistochemistry.

RESULTS

Data from cytological study allowed identification of different estrous cycle phases. Immunohistochemical analysis showed different sites of expression of steroidogenic enzymes along with tissue response throughout different phases of the estrous cycle. However, further studies are needed to characterize the derived hormones synthesized by, and the enzymes activities associated with, vaginal tissues.

CONCLUSION

Current results not only support the expression of enzymes involved in sex steroid synthesis in the wall of the vagina, they also indicate that expression changes with the stage of the cycle, both the levels and types of cells exhibiting expression. Thus, changes in proliferation of vaginal epithelial cells and the differentiation of the mucosa may be influenced by local steroid synthesis as well as circulating androgens and estrogens.

Effect of intravaginal dehydroepiandrosterone (DHEA) on the female sexual function in postmenopausal women: ERC-230 open-label study

OBJECTIVE

Intravaginal DHEA (dehydroepiandrosterone, prasterone), the exclusive precursor of androgens and estrogens in postmenopausal women, has previously been shown to improve all the domains of sexual function by a strictly local action in the vagina. The well recognized female sexual function index (FSFI) questionnaire was used in the present study.

DESIGN

The long-term effect of 52-week treatment with daily intravaginal 0.50% (6.5 mg) DHEA was evaluated on the various domains of female sexual function using the FSFI questionnaire at baseline, Week 26 and Week 52.

SUBJECTS

One hundred and fifty-four postmenopausal women with at least one mild to severe symptom of vulvovaginal atrophy (VVA) and who have completed the FSFI questionnaire at baseline and at least one post-baseline timepoint were included in the analysis.

RESULTS

The FSFI domains desire, arousal, lubrication, orgasm, satisfaction and pain were increased by 28%, 49%, 115%, 51%, 41% and 108%, respectively (p<0.0001 for all parameters) at 52 weeks vs. baseline, while the total score was increased from 13.4±0.62 at baseline to 21.5±0.82 (+60%, p<0.0001) at 52 weeks.

CONCLUSION

As the serum levels of DHEA and all its metabolites, including estradiol and testosterone, show no meaningful change, the present clinical data indicate a stimulatory effect of intravaginal DHEA through a strictly local action in agreement with the preclinical data showing that the androgens made locally from DHEA in the vagina induce an increase in local nerve density.

Accurate and sensitive liquid chromatography/tandem mass spectrometry simultaneous assay of seven steroids in monkey brain

BACKGROUND

Following its secretion mainly by the adrenal glands, dehydroepiandrosterone (DHEA) acts primarily in the cells/tissues which express the enzymes catalyzing its intracellular conversion into sex steroids by the mechanisms of intracrinology. Although reliable assays of endogenous serum steroids are now available using mass spectrometry (MS)-based technology, sample preparation from tissue matrices remains a challenge. This is especially the case with high lipid-containing tissues such as the brain. With the combination of a UPLC system with a sensitive tandem MS, it is now possible to measure endogenous unconjugated steroids in monkey brain tissue.

METHODS

A Shimadzu UPLC LC-30AD system coupled to a tandem MS AB Sciex Qtrap 6500 system was used.

RESULTS

The lower limits of quantifications are achieved at 250 pg/mL for DHEA, 200 pg/mL for 5-androstenediol (5-diol), 12 pg/mL for androstenedione (4-dione), 50 pg/mL for testosterone (Testo), 10 pg/mL for dihydrotestosterone (DHT), 4 pg/mL for estrone (E1) and 1 pg/mL for estradiol (E2). The linearity and accuracy of quality controls (QCs) and endogenous quality controls (EndoQCs) are according to the guidelines of the regulatory agencies for all seven compounds.

CONCLUSION

We describe a highly sensitive, specific and robust LC-MS/MS method for the simultaneous measurement of seven unconjugated steroids in monkey brain tissue. The single and small amount of sample required using a relatively simple preparation method should be useful for steroid assays in various peripheral tissues and thus help analysis of the role of locally-made sex steroids in the regulation of specific physiological functions.