Exposing cultured mouse ovarian follicles under increased gonadotropin tonus to aromatizable androgens influences the steroid balance and reduces oocyte meiotic capacity

In vitro fertilization outcomes in a mouse model of gender-affirming hormone therapy in transmasculine youth

OBJECTIVE

To investigate in vitro fertilization (IVF) outcomes in an adolescent transmasculine mouse model mimicking gender-affirming hormone therapy in prepubertal youth, both on testosterone (T) and after T washout.

DESIGN

Experimental laboratory study using a validated mouse model.

SETTING

University-based basic science research laboratory.

ANIMAL(S)

A total of 80 prepubertal 26-day-old C57BL/6N female mice were used in this study.

INTERVENTION(S)

Animals (n = 10/group) were implanted subcutaneously with gonadotropin-releasing hormone agonist at 3.6 mg or received sham surgery. After 21 days, they were implanted with silastic tubing containing either T 10 mg or placebo for 6 weeks. After 6 weeks, a group of animals were superovulated for immediate IVF, and another group had the implant removed and went through superovulation for IVF after 2 weeks (washout IVF). The total number of oocytes yielded, oocyte maturity rate, fertilization rate, and numbers of 2-cell embryos, 4-8-cell embryos, morula, blastocysts, and hatching blastocysts were recorded.

RESULT(S)

Testosterone treatment negatively impacted IVF outcomes in animals stimulated when receiving T, but not after T washout. Pretreatment with gonadotropin-releasing hormone agonist did not affect IVF outcomes.

CONCLUSION(S)

Although current T had a negative impact on IVF outcomes compared with controls, animals were still able to produce viable oocytes for fertilization and develop into blastocysts. Future efforts to study the impact of long-term T exposure on oocyte quality, especially aneuploidy rates, pregnancy outcomes, and live birth rates, are necessary.

Predictors of response to ovulation induction using letrozole in women with polycystic ovary syndrome

BACKGROUND

This study aimed to evaluate the predictive value of the initial screening characteristics of women with anovulatory polycystic ovary syndrome (PCOS) who did or did not respond to 2.5 mg letrozole (LET).

METHODS

The clinical and laboratory characteristics of women with PCOS who underwent LET treatment were evaluated. Women with PCOS were stratified according to their responses to LET (2.5 mg). The potential predictors of their responses to LET were estimated using logistic regression analysis.

RESULTS

Our retrospective study included 214 eligible patients with a response to 2.5 mg LET (n = 131) or no response to 2.5 mg LET (n = 83). PCOS patients who responded to 2.5 mg LET showed better outcomes than those who did not (2.5 mg LET) for pregnancy rate, live birth rate, pregnancy rate per patient, and live birth rate per patient. Logistic regression analyses showed that late menarche (odds ratio [OR], 1.79 [95% confidence intervals (CI), 1.22-2.64], P = 0.003), and increased anti-müllerian hormone (AMH) (OR, 1.12 [95% CI, 1.02-1.23], P = 0.02), baseline luteinizing hormone (LH)/ follicle stimulating hormone (FSH) (OR, 3.73 [95% CI, 2.12-6.64], P < 0.001), and free androgen index (FAI) (OR, 1.37 [95% CI, 1.16-1.64], P < 0.001) were associated with a higher possibility of no response to 2.5 mg LET.

CONCLUSIONS

PCOS patients with an increased LH/FSH ratio, AMH, FAI, and late menarche may need an increased dosage of LET for a treatment response, which could be helpful in designing a personalized treatment strategy.

General infertility workup in times of high assisted reproductive technology efficacy

The assessments of oocyte quality and quantity and endocrine profile have traditionally been the cornerstone of the general workup of couples with infertility. Over the years, several clinical, hormonal, and functional biomarkers have been adopted to assess ovarian function and identify endocrine disorders before assisted reproductive technology. Furthermore, the genetic workup of patients has drastically changed, introducing novel markers. This not only allowed the prediction of response to ovarian stimulation but also contributed toward the development of a safer and more efficient management of women undergoing assisted reproductive technology. The scope of this review is to provide an overview of the current and novel strategies adopted for the assessment of ovarian function and ovulatory and endocrine disorders in women planning to conceive. Furthermore, it aims to provide an insight in the role of novel genetic biomarkers and use of expanded carrier screening as part of preliminary workup of women with infertility.

Androgens and diminished ovarian reserve: the long road from basic science to clinical implementation. A comprehensive and systematic review with meta-analysis

OBJECTIVE

This study aimed to present a narrative review regarding androgen production, androgens' role in folliculogenesis, and the available therapeutic approaches for androgen supplementation, and to perform a systematic review and meta-analysis regarding the impact of androgens (dehydroepiandrosterone/testosterone) compared with placebo or no treatment on ovarian response and pregnancy outcomes in patients with diminished ovarian reserve and/or poor ovarian responders.

DATA SOURCES

An electronic search of MEDLINE, Embase, Cochrane Library, Cochrane Central Register of Controlled Trials, Scopus, ClinicalTrials.gov, the ISRCTN registry, and the World Health Organization International Clinical Trials Registry, was conducted for studies published until September 2021.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that compared ovarian response and/or pregnancy outcomes between the different in vitro fertilization protocols using androgens (ie, dehydroepiandrosterone and testosterone) and conventional in vitro fertilization stimulation in patients with diminished ovarian reserve and/or poor ovarian responders were included.

METHODS

The quality of each study was evaluated with the revised Cochrane risk-of-bias tool for randomized trials (RoB 2). The meta-analysis used random-effects models. All results were interpreted on the basis of intention-to-treat analysis (defined as the inclusion of all randomized patients in the denominator). Risk ratios and 95% confidence intervals were used and combined for meta-analysis.

RESULTS

No significant differences were found regarding the number of oocytes retrieved (mean difference, 0.76; 95% confidence interval, -0.35 to 1.88), mature oocytes retrieved (mean difference, 0.25; 95% confidence interval, -0.27 to 0.76), clinical pregnancy rate (risk ratio, 1.17; 95% confidence interval, 0.87-1.57), live-birth rate (risk ratio, 0.97; 95% confidence interval, 0.47-2.01), or miscarriage rate (risk ratio, 0.80; 95% confidence interval, 0.29-2.22) when dehydroepiandrosterone priming was compared with placebo or no treatment. Testosterone pretreatment yielded a higher number of oocytes retrieved (mean difference, 0.94; 95% confidence interval, 0.46-1.42), a higher clinical pregnancy rate (risk ratio, 2.07; 95% confidence interval, 1.33-3.20), and higher live-birth rate (risk ratio, 2.09; 95% confidence interval, 1.11-3.95).

CONCLUSION

Although dehydroepiandrosterone did not present a clear effect on outcomes of assisted reproductive techniques, we found a potentially beneficial effect of testosterone priming on ovarian response and pregnancy outcomes. However, results should be interpreted with caution, taking into account the low to moderate quality of the available evidence.

Nuclear and cytoplasmic quality of oocytes derived from serum-free culture of secondary follicles in vitro

In vitro culture of follicles is a promising technology to generate large quantities of mature oocytes and it could offer a novel option of assisted reproductive technologies. Here we described a 2-dimensional follicular serum-free culture system with 3-dimensional effect that can make secondary follicles develop into antral follicles (78.52%), generating developmentally mature oocytes in vitro (66.45%). The oocytes in this serum-free system completed the first meiosis; spindle assembly and chromosome congression in most oocytes matured from follicular culture were normal. However, these oocytes showed significantly lower activation and embryonic development rates, and their ability to produce Ca²⁺ oscillations was also lower in response to parthenogenetic activation, after which a 2-cell embryonic developmental block occurred. Oocytes matured from follicular culture displayed increased abnormal mitochondrial distribution and increased reactive oxygen species levels when compared to in vivo matured oocytes. These data are important for understanding the reasons for reduced developmental potential of oocytes matured from follicular culture, and for further improving the cultivation system.

The Role of Androgen Supplementation in Women With Diminished Ovarian Reserve: Time to Randomize, Not Meta-Analyze

The management of patients with diminished ovarian reserve (DOR) remains one of the most challenging tasks in IVF clinical practice. Despite the promising results obtained from animal studies regarding the importance of androgens on folliculogenesis, the evidence obtained from clinical studies remains inconclusive. This is mainly due to the lack of an evidence-based methodology applied in the available trials and to the heterogeneity in the inclusion criteria and IVF treatment protocols. In this review, we analyze the available evidence obtained from animal studies and highlight the pitfalls from the clinical studies that prevent us from closing the chapter of this line of research.

Role of androgens in the ovary

It has been well established for decades that androgens, namely testosterone (T) plays an important role in female reproductive physiology as the precursor for oestradiol (E₂). However, in the last decade a direct role for androgens, acting via the androgen receptor (AR), in female reproductive function has been confirmed. Deciphering the specific roles of androgens in ovarian function has been hindered as complete androgen resistant females cannot be generated by natural breeding. In addition, androgens can be converted into estrogens which has caused confusion when interpreting findings from pharmacological studies, as observed effects could have been mediated via the AR or estrogen receptor. The creation and analysis of genetic mouse models with global and cell-specific disruption of the Ar gene, the sole mediator of pure androgenic action, has now allowed the elucidation of a role for AR-mediated androgen actions in the regulation of normal and pathological ovarian function. This review aims to summarize findings from clinical, animal, pharmacological and novel genetic AR mouse models to provide an understanding of the important roles androgens play in the ovary, as well as providing insights into the human implications of these roles.

The role of fructose‑1,6‑bisphosphatase 1 in abnormal development of ovarian follicles caused by high testosterone concentration

The present study aimed to identify the molecular mechanisms underlying the effects of the fructose-1,6-bisphosphatase 1 (FBP1) signaling pathway within normal follicle development and in hyperandrogenism-induced abnormal follicle growth. To achieve this, murine primary follicles, granulosa cells (GCs) and theca-interstitial cells (TICs) were isolated, cultured in vitro and treated with a high concentration of androgens. A concentration of 1×10⁻⁵ mol/l testosterone was considerable to induce hyperandrogenism by MTT assay. All cells were divided into four groups, as follows: Control group, testosterone group, androgen receptor antagonist-flutamide group and flutamide + testosterone group. Flutamide was used in the present study as it blocks the effects of the androgen receptor. The mRNA expression levels of FBP1 were detected using reverse transcription-quantitative polymerase chain reaction. The expression levels and localization of FBP1 were analyzed by western blot analysis and immunofluorescence staining. The experimental results demonstrated that androgen presence stimulated follicle development, whereas excessive testosterone inhibited development. FBP1 was identified as being mainly expressed in follicles; FBP1 protein was significantly expressed in GCs of the 14-day-cultured follicle, as well as in the cytoplasm and nuclei of GCs and TICs in vitro. Testosterone increased FBP1 expression during a specific range of testosterone concentrations. Testosterone increased the expression of FBP1 within GCs. Furthermore, FBP1 and phosphoenolpyruvate carboxykinase 1 (PCK1) mRNA expression was increased in GCs treated with testosterone, whereas forkhead box protein O1 (FOXO1) and peroxisome proliferator-activated receptor γ coactivator-1α mRNA expression was significantly decreased in the testosterone group. In TICs, testosterone and flutamide inhibited the mRNA expression levels of FOXO1 and glucose-6-phosphatase enzyme, and promoted the expression of PCK1. These results suggested that the FBP1 signaling pathway may serve an important role in normal follicle growth and hyperandrogenism-induced abnormal development, which may be associated with abnormal glucose metabolism induced by high concentrations of testosterone.

The Steroid Metabolome in the Isolated Ovarian Follicle and Its Response to Androgen Exposure and Antagonism

The ovarian follicle is a major site of steroidogenesis, crucially required for normal ovarian function and female reproduction. Our understanding of androgen synthesis and metabolism in the developing follicle has been limited by the sensitivity and specificity issues of previously used assays. Here we used liquid chromatography-tandem mass spectrometry to map the stage-dependent endogenous steroid metabolome in an encapsulated in vitro follicle growth system, from murine secondary through antral follicles. Furthermore, follicles were cultured in the presence of androgen precursors, nonaromatizable active androgen, and androgen receptor (AR) antagonists to assess effects on steroidogenesis and follicle development. Cultured follicles showed a stage-dependent increase in endogenous androgen, estrogen, and progesterone production, and incubations with the sex steroid precursor dehydroepiandrosterone revealed the follicle as capable of active androgen synthesis at early developmental stages. Androgen exposure and antagonism demonstrated AR-mediated effects on follicle growth and antrum formation that followed a biphasic pattern, with low levels of androgens inducing more rapid follicle maturation and high doses inhibiting oocyte maturation and follicle growth. Crucially, our study provides evidence for an intrafollicular feedback circuit regulating steroidogenesis, with decreased follicle androgen synthesis after exogenous androgen exposure and increased androgen output after additional AR antagonist treatment. We propose that this feedback circuit helps maintain an equilibrium of androgen exposure in the developing follicle. The observed biphasic response of follicle growth and function in increasing androgen supplementations has implications for our understanding of polycystic ovary syndrome pathophysiology and the dose-dependent utility of androgens in in vitro fertilization settings.

Role of androgens in normal and pathological ovarian function

Androgens mediate their actions via the androgen receptor (AR), a member of the nuclear receptor superfamily. AR-mediated androgen action is essential in male reproductive development and function; however, only in the last decade has the suspected but unproven role for AR-mediated actions in female reproduction been firmly established. Deciphering the specific roles and precise pathways by which AR-mediated actions regulate ovarian function has been hindered by confusion on how to interpret results from pharmacological studies using androgens that can be converted into oestrogens, which exert actions via the oestrogen receptors. The generation and analysis of global and cell-specific femaleArknockout mouse models have deduced a role for AR-mediated actions in regulating ovarian function, maintaining female fertility, and have begun to unravel the mechanisms by which AR-mediated androgen actions regulate follicle health, development and ovulation. Furthermore, observational findings from human studies and animal models provide substantial evidence to support a role for AR-mediated effects not only in normal ovarian function but also in the development of the frequent ovarian pathological disorder, polycystic ovarian syndrome (PCOS). This review focuses on combining the findings from observational studies in humans, pharmacological studies and animal models to reveal the roles of AR-mediated actions in normal and pathological ovarian function. Together these findings will enable us to begin understanding the important roles of AR actions in the regulation of female fertility and ovarian ageing, as well as providing insights into the role of AR actions in the androgen-associated reproductive disorder PCOS.

The role of androgen hormones in early follicular development

Background. Although chronic hyperandrogenism, a typical feature of polycystic ovary syndrome, is often associated with disturbed reproductive performance, androgens have been shown to promote ovarian follicle growth in shorter exposures. Here, we review the main effects of androgens on the regulation of early folliculogenesis and the potential of their application in improving follicular in vitro growth. Review. Androgens may affect folliculogenesis directly via androgen receptors (ARs) or indirectly through aromatization to estrogen. ARs are highly expressed in the granulosa and theca cells of early stage follicles and slightly expressed in mature follicles. Short-term androgen exposure augments FSH receptor expression in the granulosa cells of developing follicles and enhances the FSH-induced cAMP formation necessary for the transcription of genes involved in the control of follicular cell proliferation and differentiation. AR activation also increases insulin-like growth factor (IGF-1) and its receptor gene expression in the granulosa and theca cells of growing follicles and in the oocytes of primordial follicles, thus facilitating IGF-1 actions in both follicular recruitment and subsequent development. Conclusion. During the early and intermediate stages of follicular maturation, locally produced androgens facilitate the transition of follicles from the dormant to the growing pool as well as their further development.

Multiple follicle culture supports primary follicle growth through paracrine-acting signals

In vitro follicle growth in alginate hydrogels is a unique and versatile method for studying ovarian and follicle biology that may also have implications for fertility preservation. Current culture systems support the development of isolated mouse follicles from the secondary stage onward. However, it has been a challenge to grow smaller follicles in vitro due to the dissociation of the oocyte from companion somatic cells. Recent work has demonstrated that coculturing primary follicles with mouse embryonic fibroblasts or ovarian stromal cells supports follicle survival and growth. In this study, we demonstrate that follicles themselves can exert a beneficial coculture effect. When primary follicles were cultured in groups of five or ten (multiple follicle culture), there was increased growth and survival. The multiple follicle culture approach maintained follicle integrity and resulted in the formation of antral stage follicles containing meiotically competent gametes. The growth and survival of primary follicles were highly number dependent, with the most significant enhancement observed when the largest number of follicles was grown together. Our data suggest that the follicle unit is necessary to produce the secreted factors responsible for the supportive effects of multiple follicle culture, as neither denuded oocytes, oocyte-secreted factors, nor granulosa cells alone were sufficient to support early follicle growth in vitro. Therefore, there may be signaling from both the oocyte and the follicle that enhances growth but requires both components in a feedback mechanism. This work is consistent with current in vivo models for follicle growth and thus advances the movement to recapitulate the ovarian environment in vitro.

Estradiol supports in vitro development of bovine early antral follicles

Antrum formation and estradiol (E2) secretion are specific features of oocyte and granulosa cell complexes (OGCs). This study investigates the effect of E2 on the in vitro development of bovine OGCs derived from early antral follicles as well as on the expression of genes in granulosa cells (GCs). The supplementation of culture medium with either E2 or androstenedione (A4) improved the in vitro development of OGCs and the nuclear maturation of enclosed oocytes. When OGCs were cultured in medium containing A4, developmentally competent OGCs secreted more E2 than OGCs that were not competent. In addition, fulvestrant inhibited the effect of both E2 and A4 on OGCs development. Comprehensive gene expression analysis using next-generation sequence technology was conducted for the following three types of GCs: i) GCs of OGCs cultured for 4 days with E2 (1 μg/ml; E2(+)), ii) GCs of OGCs cultured for 4 days without E2 (E2(−)) or iii) OGCs that formed clear antrum after 8 days of in vitro culture in medium containing E2 (1 μg/ml; AF group). GCs of the E2(+) group had a similar gene expression profile to the profile reported previously for the in vivo development of large follicles. This genetic profile included factors implicated in the up-regulation of E2 biosynthesis and down-regulation of cytoskeleton and extracellular matrices. In addition, a novel gene expression profile was found in the AF group. In conclusion, E2 impacts the gene expression profile of GCs to support the in vitro development of OGCs.

The role of androgens in follicle maturation and ovulation induction: friend or foe of infertility treatment?

BACKGROUND

Effects of androgens on follicle maturation have been controversial for some time. Here, we review the potential of their applications in improving human ovulation induction, based on human and animal data, reported in the literature.

METHODS

We reviewed the published literature for the years 2005-2011, using relevant key words, in PubMed, Medline and Cochrane reviews, and then performed secondary reviews of referenced articles, which previously had not been known or preceded the searched time period. A total of 217 publications were reviewed.

RESULTS

Contrary to widely held opinion, recent data, mostly developed in the mouse, convincingly demonstrate essential contribution of androgens to normal follicle maturation and, therefore, female fertility. Androgens appear most engaged at preantral and antral stages, primarily affect granulosa cells, and exert effects via androgen receptors (AR) through transcriptional regulation but also in non-genomic ways, with ligand-activated AR modulating follicle stimulating hormone (FSH) activity in granulosa cells. While some androgens, like testosterone (T) and dehydroepiandrosterone (DHEA), appear effective in improving functional ovarian reserve (FOR) in women with diminished ovarian reserve (DOR), others may even exert opposite effects. Such differences in androgens may, at least partially, reflect different levels of agonism to AR.

DISCUSSION

Selective androgens appear capable of improving early stages of folliculogenesis. They, therefore, may represent forerunners of a completely new class of ovulation-inducing medications, which, in contrast to gonadotropins, affect follicle maturation at much earlier stages.