Men homozygous for an inactivating mutation of the follicle-stimulating hormone (FSH) receptor gene present variable suppression of spermatogenesis and fertility

FSH increases lipid droplet content by regulating the expression of genes related to lipid storage in Rat Sertoli cells

Sertoli cells (SCs) are essential for appropriate spermatogenesis. From a metabolic standpoint, they catabolize glucose and provide germ cells with lactate, which is their main energy source. SCs also oxidize fatty acids (FAs), which are stored as triacylglycerides (TAGs) within lipid droplets (LDs), to fulfill their own energy requirements. On the other hand, it has been demonstrated that FSH regulates some of SCs functions, but little is known about its effect on lipid metabolism. In the present study, we aimed to analyze FSH-mediated regulation of (1) lipid storage in LDs and (2) the expression of genes involved in FAs activation and TAG synthesis and storage in SCs. SCs obtained from 20-day-old rats were cultured for different incubation periods with FSH (100 ng/ml). It was observed that FSH increased LD content and TAG levels in SCs. There were also increments in the expression of Plin1, Fabp5, Acsl1, Acsl4, Gpat3, and Dgat1, which suggests that these proteins may mediate the increase in TAGs and LDs elicited by FSH. Regarding the signaling involved in FSH actions, it was observed that dbcAMP increased LD, and H89, a PKA inhibitor, inhibited FSH stimulus. Also, dbcAMP increased Plin2, Fabp5, Acsl1, Acsl4, and Dgat1 mRNA levels, confirming a role of the cAMP/PKA pathway in the regulation of lipid storage in SCs. Altogether, these results suggest that FSH, via the cAMP/PKA pathway, regulates lipid storage in SCs ensuring the availability of substrates to satisfy their energy requirements.

Lycium barbarum polysaccharide alleviates ferroptosis in Sertoli cells through NRF2/SLC7A11/GPX4 pathway and ameliorates DEHP-induced male reproductive damage in mice

Di-(2-ethylhexyl)phthalate (DEHP) is a common plasticizer that has been shown to significantly negatively affect male reproductive health. On the other hand, Lycium barbarum polysaccharide (LBP) has been shown to improve reproductive function. Therefore, we hypothesized that LBP may ameliorate DEHP-induced male reproductive damage. Herein, we found that LBP could alleviate DEHP-induced testicular damage and sperm abnormalities. Furthermore, histomorphological analysis of mice testis revealed that LBP primarily ameliorated the DEHP-induced male reproductive damage by targeting Sertoli cells. Moreover, the detection of the function-related genes of Sertoli cells confirmed this finding. The serum of mice in the Control, DEHP, and DEHP+LBP groups was analyzed using non-targeted metabolomics to further elucidate the mechanism of action of LBP in improving DEHP-induced male reproductive damage. According to the results, the differential metabolites were mainly enriched in the glutamate metabolism pathway, implying that LBP may alleviate the ferroptosis-related DEHP-induced testicular injury. Related ferroptosis markers were also found in mice testis. These findings collectively suggest that LBP may ameliorate DEHP-induced testicular injury via alleviating ferroptosis in Sertoli cells. To clarify the specific mechanism, we constructed a cell model in vitro by treating TM4 cells (the Sertoli cell line) with LBP and MEHP (the in vivo DEHP metabolite). Our findings revealed that LBP can improve the function of DEHP-affected Sertoli cells. Furthermore, the analysis of lipid peroxidation, Fe2+ content, and ferroptosis-related protein expressions demonstrated that LBP could ameliorate MEHP-induced ferroptosis in TM4 cells. To clarify the specific mechanism, glutamate metabolism-related proteins involved in the ferroptosis pathway were detected. According to the results, there were significant changes in the expression of NRF2, SLC7A11 and GPX4 proteins, which are involved in the ferroptosis glutamate metabolism pathway. Furthermore, supplementation of NRF2, SLC7A11, and GPX4 inhibitors (ML385, Erastin, and RSL3, respectively) blocked the therapeutic effect of LBP in alleviating MEHP-induced ferroptosis in TM4 cells, implying that LBP could also ameliorate MEHP-induced ferroptosis via the NRF2/SLC7A11/GPX4 pathway. In summary, these findings show that LBP can alleviate DEHP/MEHP-induced ferroptosis through the NRF2/SLC7A11/GPX4 pathway, ameliorating Sertoli cell dysfunction and improving the DEHP-induced male reproductive damage. Therefore, the clinical administration of LBP could be an effective strategy for preventing DEHP-induced male reproductive injury.

Hypogonadotropic hypogonadism as a cause of NOA and its treatment

ABSTRACT

Hypogonadotropic hypogonadism (HH) represents a relatively rare cause of nonobstructive azoospermia (NOA), but its knowledge is crucial for the clinical andrologists, as it represents a condition that can be corrected with medical therapy in 3 quarters of cases. There are forms of congenital HH, whether or not associated with an absent sense of smell (anosmic HH or Kallmann syndrome, and normosmic HH, respectively), and forms of acquired HH. In congenital HH, complete absence of pubertal development is characteristic. On the other hand, if the deficit occurs after the time of pubertal development, as in acquired HH patients, infertility and typical symptoms of late-onset hypogonadism are the main reasons for seeking medical assistance. Gonadotropin-releasing hormone (GnRH) or gonadotropin replacement therapy is the mainstay of drug therapy and offers excellent results, although a small but significant proportion of patients do not achieve sufficient responses.

Contraceptive efficacy: Determining the threshold for effective suppression based on sperm concentration, motility, and morphology

INTRODCTION

Human spermatogenesis is a complex process that transforms spermatogonial stem cells through mitosis and meiosis to spermatozoa. Testosterone is the key regulator of the terminal stages of meiosis, adherence of spermatids to Sertoli cells, and spermiation. Follicle-stimulating hormone (FSH) may be required for early spermatogenesis and is important for maintaining normal spermatogenesis in men. Hormonal contraception suppresses FSH, luteinizing hormone, and intratesticular testosterone concentration, resulting in marked suppression of sperm output.

RESULTS

Clinical trials using testosterone alone or testosterone plus progestin demonstrate that sustained suppression of sperm concentration to ≤1 million/mL is sufficient to prevent pregnancy in the female partner. New agents that target spermatogenesis could use this as a target for contraceptive efficacy while others that block sperm function or transport may require a lower threshold. When sperm concentrations are suppressed to such low levels, measurement of sperm motility and morphology is technically difficult and unnecessary. With current data from fertile and infertile men, it is not possible to establish a lower limit of sperm motility or percent normal morphology that equates to the prevention of conception. New compounds that decrease sperm motility or alter sperm morphology may need to demonstrate a complete absence of sperm motility or altered morphology in all spermatozoa in the ejaculate. Sperm function tests may be useful depending on the mechanism of action of each new compound.

CONCLUSION

Monitoring of sperm surrogate markers to ensure effective contraception relies on laboratories experienced in semen analyses. The development of at-home tests to assess sperm parameters has progressed rapidly. Some tests have been assessed in clinical trials and approved by regulatory agencies for at-home use for fertility assessment. However, caution must be exercised in using these tests as many have not been rigorously validated against semen parameters measured in laboratories by trained technologists using standardized tests defined in the World Health Organization Semen Manual.

Restoring function to inactivating G protein-coupled receptor variants in the hypothalamic-pituitary-gonadal axis1

G protein-coupled receptors (GPCRs) are central to the functioning of the hypothalamic-pituitary-gonadal axis (HPG axis) and include the rhodopsin-like GPCR family members, neurokinin 3 receptor, kappa-opioid receptor, kisspeptin 1 receptor, gonadotropin-releasing hormone receptor, and the gonadotropin receptors, luteinizing hormone/choriogonadotropin receptor and follicle-stimulating hormone receptor. Unsurprisingly, inactivating variants of these receptors have been implicated in a spectrum of reproductive phenotypes, including failure to undergo puberty, and infertility. Clinical induction of puberty in patients harbouring such variants is possible, but restoration of fertility is not always a realisable outcome, particularly for those patients suffering from primary hypogonadism. Thus, novel pharmaceuticals and/or a fundamental change in approach to treating these patients are required. The increasing wealth of data describing the effects of coding-region genetic variants on GPCR function has highlighted that the majority appear to be dysfunctional as a result of misfolding of the encoded receptor protein, which, in turn, results in impaired receptor trafficking through the secretory pathway to the cell surface. As such, these intracellularly retained receptors may be amenable to 'rescue' using a pharmacological chaperone (PC)-based approach. PCs are small, cell permeant molecules hypothesised to interact with misfolded intracellularly retained proteins, stabilising their folding and promoting their trafficking through the secretory pathway. In support of the use of this approach as a viable therapeutic option, it has been observed that many rescued variant GPCRs retain at least a degree of functionality when 'rescued' to the cell surface. In this review, we examine the GPCR PC research landscape, focussing on the rescue of inactivating variant GPCRs with important roles in the HPG axis, and describe what is known regarding the mechanisms by which PCs restore trafficking and function. We also discuss some of the merits and obstacles associated with taking this approach forward into a clinical setting.

Combined Multiplexed Phage Display, High-Throughput Sequencing, and Functional Assays as a Platform for Identifying Modulatory VHHs Targeting the FSHR

Developing modulatory antibodies against G protein-coupled receptors is challenging. In this study, we targeted the follicle-stimulating hormone receptor (FSHR), a significant regulator of reproduction, with variable domains of heavy chain-only antibodies (VHHs). We built two immune VHH libraries and submitted them to multiplexed phage display approaches. We used next-generation sequencing to identify 34 clusters of specifically enriched sequences that were functionally assessed in a primary screen based on a cAMP response element (CRE)-dependent reporter gene assay. In this assay, 23 VHHs displayed negative or positive modulation of FSH-induced responses, suggesting a high success rate of the multiplexed strategy. We then focused on the largest cluster identified (i.e., PRC1) that displayed positive modulation of FSH action. We demonstrated that PRC1 specifically binds to the human FSHR and human FSHR/FSH complex while potentiating FSH-induced cAMP production and Gs recruitment. We conclude that the improved selection strategy reported here is effective for rapidly identifying functionally active VHHs and could be adapted to target other challenging membrane receptors. This study also led to the identification of PRC1, the first potential positive modulator VHH reported for the human FSHR.

Gonadotropins in the Management of Couple Infertility: Toward the Rational Use of an Empirical Therapy

Although epidemiology shows that both men and woman can experience infertility, the female partner usually experiences most of the diagnostic and therapeutic burden. Thus, management of couple infertility is a unique example of gender inequality. The use of exogenous gonadotropins in assisted reproductive technology (ART) to induce multifollicular growth is well consolidated in women, but the same is not done with the same level of confidence and purpose in infertile men. Indeed, the treatment of idiopathic male infertility is based on an empirical approach that involves administration of the follicle-stimulating hormone (FSH) in dosages within the replacement therapy range. This treatment has so far been attempted when the endogenous FSH serum levels are within the reference ranges. According to the most recent evidence, a "substitutive" FSH administration may not be effective enough, while a stimulatory approach could boost spermatogenesis over its basal levels without adverse extragonadal effects. This article aims to describe the rationale behind the empirical application of gonadotropins in couple infertility, highlighting the need for a change in the therapeutic approach, especially for the male partner.

Current understanding of the genomic abnormities in premature ovarian failure: chance for early diagnosis and management

Premature ovarian failure (POF) is an insidious cause of female infertility and a devastating condition for women. POF also has a strong familial and heterogeneous genetic background. Management of POF is complicated by the variable etiology and presentation, which are generally characterized by abnormal hormone levels, gene instability and ovarian dysgenesis. To date, abnormal regulation associated with POF has been found in a small number of genes, including autosomal and sex chromosomal genes in folliculogenesis, granulosa cells, and oocytes. Due to the complex genomic contributions, ascertaining the exact causative mechanisms has been challenging in POF, and many pathogenic genomic characteristics have yet to be elucidated. However, emerging research has provided new insights into genomic variation in POF as well as novel etiological factors, pathogenic mechanisms and therapeutic intervention approaches. Meanwhile, scattered studies of transcriptional regulation revealed that ovarian cell function also depends on specific biomarker gene expression, which can influence protein activities, thus causing POF. In this review, we summarized the latest research and issues related to the genomic basis for POF and focused on insights gained from their biological effects and pathogenic mechanisms in POF. The present integrated studies of genomic variants, gene expression and related protein abnormalities were structured to establish the role of etiological genes associated with POF. In addition, we describe the design of some ongoing clinical trials that may suggest safe, feasible and effective approaches to improve the diagnosis and therapy of POF, such as Filgrastim, goserelin, resveratrol, natural plant antitoxin, Kuntai capsule et al. Understanding the candidate genomic characteristics in POF is beneficial for the early diagnosis of POF and provides appropriate methods for prevention and drug treatment. Additional efforts to clarify the POF genetic background are necessary and are beneficial for researchers and clinicians regarding genetic counseling and clinical practice. Taken together, recent genomic explorations have shown great potential to elucidate POF management in women and are stepping from the bench to the bedside.

Activating Transcription Factor 3 Stimulates Follicle-Stimulating Hormone-β Expression In Vitro But Is Dispensable for Follicle-Stimulating Hormone Production in Murine Gonadotropes In Vivo

Follicle-stimulating hormone (FSH), a dimeric glycoprotein produced by pituitary gonadotrope cells, regulates spermatogenesis in males and ovarian follicle growth in females. Hypothalamic gonadotropin-releasing hormone (GnRH) stimulates FSHβ subunit gene (Fshb) transcription, though the underlying mechanisms are poorly understood. To address this gap in knowledge, we examined changes in pituitary gene expression in GnRH-deficient mice (hpg) treated with a regimen of exogenous GnRH that increases pituitary Fshb but not luteinizing hormone β (Lhb) messenger RNA levels. Activating transcription factor 3 (Atf3) was among the most upregulated genes. Activating transcription factor 3 (ATF3) can heterodimerize with members of the activator protein 1 family to regulate gene transcription. Co-expression of ATF3 with JunB stimulated murine Fshb, but not Lhb, promoter-reporter activity in homologous LβT2b cells. ATF3 also synergized with a constitutively active activin type I receptor to increase endogenous Fshb expression in these cells. Nevertheless, FSH production was intact in gonadotrope-specific Atf3 knockout [conditional knockout (cKO)] mice. Ovarian follicle development, ovulation, and litter sizes were equivalent between cKOs and controls. Testis weights and sperm counts did not differ between genotypes. Following gonadectomy, increases in LH secretion were enhanced in cKO animals. Though FSH levels did not differ between genotypes, post-gonadectomy increases in pituitary Fshb and gonadotropin α subunit expression were more pronounced in cKO than control mice. These data indicate that ATF3 can selectively stimulate Fshb expression in vitro but is not required for FSH production in vivo.

Progress in genome-wide association studies of age at natural menopause

Menopause is not only the end of reproductive life, it is also related to diseases such as hyperlipidaemia, atherosclerotic cardiovascular disease, osteoporosis and breast cancer. Traditional epidemiological studies have found that heredity is the main determinant of age at natural menopause (ANM). Early studies on genetic factors were limited to candidate gene studies. Menopause age is not inherited by a single gene, but is the result of multiple gene effects. With the development of genomic technology, the Reproductive Genetics Consortium conducted several genome-wide association studies on ANM in people of European descent, and found that defects in DNA damage repair pathways were the main genetic mechanism. In recent years, due to the ethnic heterogeneity of ANM, there has been further development of global studies into multi-ethnic and trans-ethnic genome-wide association studies. Further genetic and epidemiological studies, including polygenetic score and genetic mechanism research, should be conducted to investigate the pathogenesis and mechanism with respect to menopause and its related diseases.

Follicle-stimulating hormone treatment for male factor infertility

Follicle-stimulating hormone (FSH) treatment has been proven effective in stimulating spermatogenesis and improving the reproductive ability of men with hypogonadotropic hypogonadism, while the usefulness of such a treatment in infertile patients with normal pituitary function is restricted to a subgroup of responders that, however, cannot be identified by the current diagnostic tools before treatment. In this review we summarize the role played by FSH in the modulation of spermatogenesis, the effect of FSH treatment at a standard replacement dose and at higher dose on sperm parameters, spontaneous and in vitro fertilization pregnancy rates, and the efforts made to identify possible responders to FSH treatment.

Ferroptosis is critical for phthalates driving the blood-testis barrier dysfunction via targeting transferrin receptor

The global rate of human male infertility is rising at an alarming rate owing to environmental and lifestyle changes. Phthalates are the most hazardous chemical additives in plastics and have an apparently negative impact on the function of male reproductive system. Ferroptosis is a recently described form of iron-dependent cell death and has been linked to several diseases. Transferrin receptor (TfRC), a specific ferroptosis marker, is a universal iron importer for all cells using extracellular transferrin. We aim to investigate the potential involvement of ferroptosis during male reproductive toxicity, and provide means for drawing conclusions on the effect of ferroptosis in phthalates-induced male reproductive disease. In this study, we found that di (2-ethylhexyl) phthalate (DEHP) triggered blood-testis barrier (BTB) dysfunction in the mouse testicular tissues. DEHP also induced mitochondrial morphological changes and lipid peroxidation, which are manifestations of ferroptosis. As the primary metabolite of DEHP, mono-2-ethylhexyl phthalate (MEHP) induced ferroptosis by inhibiting glutathione defense network and increasing lipid peroxidation. TfRC knockdown blocked MEHP-induced ferroptosis by decreasing mitochondrial and intracellular levels of Fe²⁺. Our findings indicate that TfRC can regulate Sertoli cell ferroptosis and therefore is a novel therapeutic molecule for reproductive disorders in male patients with infertility.

Genetic variants of G-protein coupled receptors associated with pubertal disorders

Background

The human hypothalamic-pituitary-gonadal (HPG) axis is the regulatory center for pubertal development. This axis involves six G-protein coupled receptors (GPCRs) encoded by KISS1R, TACR3, PROKR2, GNRHR, LHCGR, and FSHR.

Methods

Previous studies have identified several rare variants of the six GPCR genes in patients with pubertal disorders. In vitro assays and animal studies have provided information on the function of wild-type and variant GPCRs.

Main Findings

Of the six GPCRs, those encoded by KISS1R and TACR3 are likely to reside at the top of the HPG axis. Several loss-of-function variants in the six genes were shown to cause late/absent puberty. In particular, variants in KISS1R, TACR3, PROKR2, and GNRHR lead to hypogonadotropic hypogonadism in autosomal dominant, recessive, and oligogenic manners. Furthermore, a few gain-of-function variants of KISS1R, PROKR2, and LHCGR have been implicated in precocious puberty. The human HPG axis may contain additional GPCRs.

Conclusion

The six GPCRs in the HPG axis govern pubertal development through fine-tuning of hormone secretion. Rare sequence variants in these genes jointly account for a certain percentage of genetic causes of pubertal disorders. Still, much remains to be clarified about the molecular network involving the six GPCRs.

Circular RNAs: Novel Biomarkers in Spermatogenesis Defects and Male Infertility

Circular RNAs (circRNAs) are a new class of endogenous non-coding RNAs involved in several cellular and biological processes, including gene expression regulation, microRNA function, transcription regulation, and translation modification. Therefore, these non-coding RNAs have important roles in the pathogenesis of various diseases. Male infertility is mainly due to abnormal sperm parameters such as motility, morphology, and concentration. Recent studies have confirmed the role of circRNAs in spermatogenesis, and the expression of several circRNAs is confirmed in seminal plasma, spermatozoa, and testicular tissue. It is suggested that deregulation of circRNAs is involved in different types of male infertility, including azoospermia, oligozoospermia, and asthenozoospermia. In the present review, we aimed to discuss the potential roles of circRNAs in spermatogenesis failure, sperm defects, and male infertility. Due to their conserved and special structure and tissue-specific expression pattern, circRNAs can be applied as reliable noninvasive molecular biomarkers, therapeutic and pharmaceutical targets in male infertility.

Revisiting the gonadotropic regulation of mammalian spermatogenesis: evolving lessons during the past decade

Spermatogenesis is a multi-step process of male germ cell (Gc) division and differentiation which occurs in the seminiferous tubules of the testes under the regulation of gonadotropins - Follicle Stimulating Hormone (FSH) and Luteinising hormone (LH). It is a highly coordinated event regulated by the surrounding somatic testicular cells such as the Sertoli cells (Sc), Leydig cells (Lc), and Peritubular myoid cells (PTc). FSH targets Sc and supports the expansion and differentiation of pre-meiotic Gc, whereas, LH operates via Lc to produce Testosterone (T), the testicular androgen. T acts on all somatic cells e.g.- Lc, PTc and Sc, and promotes the blood-testis barrier (BTB) formation, completion of Gc meiosis, and spermiation. Studies with hypophysectomised or chemically ablated animal models and hypogonadal (hpg) mice supplemented with gonadotropins to genetically manipulated mouse models have revealed the selective and synergistic role(s) of hormones in regulating male fertility. We here have briefly summarized the present concept of hormonal control of spermatogenesis in rodents and primates. We also have highlighted some of the key critical questions yet to be answered in the field of male reproductive health which might have potential implications for infertility and contraceptive research in the future.

Real-world evidence analysis of the follicle-stimulating hormone use in male idiopathic infertility

Male idiopathic infertility remains a therapeutic challenge in the couple infertility management. In this setting, an empirical treatment with follicle-stimulating hormone (FSH) is allowed, although not recommended. Twenty-one clinical trials and four meta-analyses highlighted an overall increased pregnancy rate in case of FSH administration, but the indiscriminate FSH prescription is still unsupported by clinical evidence in idiopathic infertility. This context could represent an example in which real-world data (RWD) could add useful information. From a nationwide clinical practice survey performed in Italy, emerged the clinicians' attitude to prescribe FSH in the case of impaired semen with a significant improvement of semen parameters, identifying FSH treatment as a therapeutic card in the real-life management. Although more robust data are still needed to optimize FSH treatment in male idiopathic infertility, RWD should be included in the body of evidence considered in healthcare decision-making.

Testicular Sertoli Cell Hormones in Differences in Sex Development

The Sertoli cells of the testes play an essential role during gonadal development, in addition to supporting subsequent germ cell survival and spermatogenesis. Anti-Müllerian hormone (AMH) is a member of the TGF-β superfamily, which is secreted by immature Sertoli cells from the 8th week of fetal gestation. lnhibin B is a glycoprotein, which is produced by the Sertoli cells from early in fetal development. In people with a Difference or Disorder of Sex Development (DSD), these hormones may be useful to determine the presence of testicular tissue and potential for spermatogenesis. However, fetal Sertoli cell development and function is often dysregulated in DSD conditions and altered production of Sertoli cell hormones may be detected throughout the life course in these individuals. As such this review will consider the role of AMH and inhibin B in individuals with DSD.

Functional Importance of Mini-Puberty in Spermatogenic Stem Cell Formation

Primordial germ cells nesting in the fetal testis give rise to gonocytes. The gonocytes then transform into spermatogenic stem cells (SSCs) during the neonatal period and thereafter serve as a lifetime source of spermatogenesis. Therefore, gonocyte to SSC transformation is quite an important process that supports fertility in males. During the gonocyte to SSC transformation, morphological and transcriptomic changes sequentially occur and gonocytes migrate from the center to the peripheral region of the seminiferous tubules. However, extrinsic signals which trigger the transcriptomic changes as well as the migration are not yet fully clarified. Recent studies have drawn attention to the temporal activation of the hypothalamic-pituitary-gonadal axis during the neonatal stage which occurs concurrently with SSC formation. This phenomenon is called mini-puberty, and recent studies on human cryptorchid patients as well as animal models partially support the hypothesis that mini-puberty plays pivotal roles in gonocyte-to-SSC transformation. Focusing on this point, here, we aimed to discuss the latest knowledge on the importance of mini-puberty in spermatogenesis in this review.

Can nanomaterials support the diagnosis and treatment of human infertility? A preliminary review

Human infertilities are disorders that afflict many people all over the world. Both male and female reproductive systems must work together in a precise and coordinated manner and infertility has a wide range of problems for this system. Recent advances in nanomedicine immensely helped design the diagnostic and therapeutic approaches to alleviate human infertility in both sexes. Nanoscience has recently been used by researchers to increase the detection limit of infertility-related biomarkers via fabricating sensitive nanobiosensors for detecting follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-müllerian hormone (AMH), pregnancy-associated plasma protein-A (PAPP-A), progesterone, and testosterone. At the same time, a variety of nanostructures, including magnetic nanoparticles (i.e., zinc nanoparticles, cerium nanoparticles, gold nanoparticles, silver nanoparticles), nano-vitamins, extracellular vesicles, and spermbots, have shown promising outcomes in the treatment of human infertilities. Despite recent advancements, some nanostructures might have toxic effects on cells, especially germ cells, and must be optimized with the right ingredients, such as antioxidants, nutrients, and vitamins, to obtain the right strategy to treat and detect human infertilities. This review presents recent developments in nanotechnology regarding impairments still faced by human infertility. New perspectives for further use of nanotechnology in reproductive medicine studies are also discussed. In conclusion, nanotechnology, as a tool for reproductive medicine, has been considered to help overcome current impairments.

Spatiotemporal Small Non-coding RNAs Expressed in the Germline as an Early Biomarker of Testicular Toxicity and Transgenerational Effects Caused by Prenatal Exposure to Nanosized Particles

In recent years, an apparent decline in human sperm quality has been observed worldwide. One in every 5.5 couples suffers from infertility, with male reproductive problems contributing to nearly 40% of all infertility cases. Although the reasons for the increasing number of infertility cases are largely unknown, both genetic and environmental factors can be contributing factors. In particular, exposure to chemical substances during mammalian male germ cell development has been linked to an increased risk of infertility in later life owing to defective sperm production, reproductive tract obstruction, inflammation, and sexual disorders. Prenatal exposure to nanomaterials (NMs) is no exception. In animal experiments, maternal exposure to NMs has been reported to affect the reproductive health of male offspring. Male germ cells require multiple epigenetic reprogramming events during their lifespan to acquire reproductive capacity. Given that spermatozoa deliver the paternal genome to oocytes upon fertilization, we hypothesized that maternal exposure to NMs negatively affects male germ cells by altering epigenetic regulation, which may in turn affect embryo development. Small non-coding RNAs (including microRNAs, PIWI-interacting RNAs, tRNA-derived small RNAs, and rRNA-derived small RNAs), which are differentially expressed in mammalian male germ cells in a spatiotemporal manner, could play important regulatory roles in spermatogenesis and embryogenesis. Thus, the evaluation of RNAs responsible for sperm fertility is of great interest in reproductive toxicology and medicine. However, whether the effect of maternal exposure to NMs on spermatogenesis in the offspring (intergenerational effects) really triggers multigenerational effects remains unclear, and infertility biomarkers for evaluating paternal inheritance have not been identified to date. In this review, existing lines of evidence on the effects of prenatal exposure to NMs on male reproduction are summarized. A working hypothesis of the transgenerational effects of sperm-derived epigenomic changes in the F1 generation is presented, in that such maternal exposure could affect early embryonic development followed by deficits in neurodevelopment and male reproduction in the F2 generation.

Human INHBB Gene Variant (c.1079T>C:p.Met360Thr) Alters Testis Germ Cell Content, but Does Not Impact Fertility in Mice

Testicular-derived inhibin B (α/β B dimers) acts in an endocrine manner to suppress pituitary production of follicle-stimulating hormone (FSH), by blocking the actions of activins (β A/B/β A/B dimers). Previously, we identified a homozygous genetic variant (c.1079T>C:p.Met360Thr) arising from uniparental disomy of chromosome 2 in the INHBB gene (β B-subunit of inhibin B and activin B) in a man suffering from infertility (azoospermia). In this study, we aimed to test the causality of the p.Met360Thr variant in INHBB and testis function. Here, we used CRISPR/Cas9 technology to generate InhbbM364T/M364T mice, where mouse INHBB p.Met364 corresponds with human p.Met360. Surprisingly, we found that the testes of male InhbbM364T/M364T mutant mice were significantly larger compared with those of aged-matched wildtype littermates at 12 and 24 weeks of age. This was attributed to a significant increase in Sertoli cell and round spermatid number and, consequently, seminiferous tubule area in InhbbM364T/M364T males compared to wildtype males. Despite this testis phenotype, male InhbbM364T/M364T mutant mice retained normal fertility. Serum hormone analyses, however, indicated that the InhbbM364T variant resulted in reduced circulating levels of activin B but did not affect FSH production. We also examined the effect of this p.Met360Thr and an additional INHBB variant (c.314C>T: p.Thr105Met) found in another infertile man on inhibin B and activin B in vitro biosynthesis. We found that both INHBB variants resulted in a significant disruption to activin B in vitro biosynthesis. Together, this analysis supports that INHBB variants that limit activin B production have consequences for testis composition in males.

An update on male infertility and intratesticular testosterone-insight into novel serum biomarkers

Intratesticular testosterone is vital for spermatogenesis, male fertility, and virility. Currently the only method to assess levels of intratesticular testosterone is to perform testicular biopsy which is invasive and can lead to several complications. Approaches to assess intratesticular testosterone have been understudied but hold promise as future male contraceptive agents and may grant the ability to monitor patients undergoing hormonal changes from therapeutic and diagnostic perspectives. Previous studies have sought to assess the utility of 17-hydroxyprogesterone (17-OHP) and insulin-like factor 3 (INSL3) as accurate surrogate biomarkers of intratesticular testosterone. The aim of this review is thus to highlight the importance of intratesticular testosterone and the consequent advances that have been made to elucidate the potential of biomarkers for intratesticular testosterone in the context of male infertility.

Targeting trafficking as a therapeutic avenue for misfolded GPCRs leading to endocrine diseases

G protein-coupled receptors (GPCRs) are plasma membrane proteins associated with an array of functions. Mutations in these receptors lead to a number of genetic diseases, including diseases involving the endocrine system. A particular subset of loss-of-function mutant GPCRs are misfolded receptors unable to traffic to their site of function (i.e. the cell surface plasma membrane). Endocrine disorders in humans caused by GPCR misfolding include, among others, hypo- and hyper-gonadotropic hypogonadism, morbid obesity, familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism, X-linked nephrogenic diabetes insipidus, congenital hypothyroidism, and familial glucocorticoid resistance. Several in vitro and in vivo experimental approaches have been employed to restore function of some misfolded GPCRs linked to endocrine disfunction. The most promising approach is by employing pharmacological chaperones or pharmacoperones, which assist abnormally and incompletely folded proteins to refold correctly and adopt a more stable configuration to pass the scrutiny of the cell's quality control system, thereby correcting misrouting. This review covers the most important aspects that regulate folding and traffic of newly synthesized proteins, as well as the experimental approaches targeted to overcome protein misfolding, with special focus on GPCRs involved in endocrine diseases.

Genetic variants of gonadotrophins and their receptors: Impact on the diagnosis and management of the infertile patient

This narrative review is concerned with genetic variants of the genes encoding gonadotrophin subunits and their receptors, as well as their implications into the diagnosis and treatment of infertility. We first review briefly the basics of molecular biology and biochemistry of gonadotrophin and gonadotrophin receptor structure and function, then describe the phenotypic effects of polymorphisms and mutations of these genes, followed by diagnostic aspects. We will then summarise the information that inactivating gonadotrophin receptor mutations have provided about the controversial topic of extragonadal gonadotrophin action. Finally, we will close with the current and future therapeutic approaches on patients with gonadotrophin and their receptor mutations.

The Roles of Luteinizing Hormone, Follicle-Stimulating Hormone and Testosterone in Spermatogenesis and Folliculogenesis Revisited

Spermatogenesis and folliculogenesis involve cell–cell interactions and gene expression orchestrated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). FSH regulates the proliferation and maturation of germ cells independently and in combination with LH. In humans, the requirement for high intratesticular testosterone (T) concentration in spermatogenesis remains both a dogma and an enigma, as it greatly exceeds the requirement for androgen receptor (AR) activation. Several data have challenged this dogma. Here we report our findings on a man with mutant LH beta subunit (LHβ) that markedly reduced T production to 1–2% of normal., but despite this minimal LH stimulation, T production by scarce mature Leydig cells was sufficient to initiate and maintain complete spermatogenesis. Also, in the LH receptor (LHR) knockout (LuRKO) mice, low-dose T supplementation was able to maintain spermatogenesis. In addition, in antiandrogen-treated LuRKO mice, devoid of T action, the transgenic expression of a constitutively activating follicle stimulating hormone receptor (FSHR) mutant was able to rescue spermatogenesis and fertility. Based on rodent models, it is believed that gonadotropin-dependent follicular growth begins at the antral stage, but models of FSHR inactivation in women contradict this claim. The complete loss of FSHR function results in the complete early blockage of folliculogenesis at the primary stage, with a high density of follicles of the prepubertal type. These results should prompt the reassessment of the role of gonadotropins in spermatogenesis, folliculogenesis and therapeutic applications in human hypogonadism and infertility.

Misfolded G Protein-Coupled Receptors and Endocrine Disease. Molecular Mechanisms and Therapeutic Prospects

Misfolding of G protein-coupled receptors (GPCRs) caused by mutations frequently leads to disease due to intracellular trapping of the conformationally abnormal receptor. Several endocrine diseases due to inactivating mutations in GPCRs have been described, including X-linked nephrogenic diabetes insipidus, thyroid disorders, familial hypocalciuric hypercalcemia, obesity, familial glucocorticoid deficiency [melanocortin-2 receptor, MC2R (also known as adrenocorticotropin receptor, ACTHR), and reproductive disorders. In these mutant receptors, misfolding leads to endoplasmic reticulum retention, increased intracellular degradation, and deficient trafficking of the abnormal receptor to the cell surface plasma membrane, causing inability of the receptor to interact with agonists and trigger intracellular signaling. In this review, we discuss the mechanisms whereby mutations in GPCRs involved in endocrine function in humans lead to misfolding, decreased plasma membrane expression of the receptor protein, and loss-of-function diseases, and also describe several experimental approaches employed to rescue trafficking and function of the misfolded receptors. Special attention is given to misfolded GPCRs that regulate reproductive function, given the key role played by these particular membrane receptors in sexual development and fertility, and recent reports on promising therapeutic interventions targeting trafficking of these defective proteins to rescue completely or partially their normal function.

Interpretation of reproductive hormones before, during and after the pubertal transition-Identifying health and disordered puberty

Puberty is a process of transition from childhood to adult reproductive capacity, governed by the reactivation of the hypothalamic-pituitary-gonadal axis after a long period of dormancy in mid-childhood. As such, the reproductive hormones are in a state of flux during the adolescent years, and interpretation of both the onset of healthy, concordant puberty and the differentiation of precocious, delayed or disordered puberty, can be challenging. This review is focused on the description of the endocrine axes in healthy puberty and the markers of disorders of puberty that can aid diagnosis and management for patients with these conditions. It will cover the hypothalamic, pituitary and gonadal hormone systems, the dynamic changes that occur during puberty, conditions leading to precocious, delayed or absent puberty and other syndromes with disordered puberty, and the biochemical diagnosis of these different disorders of puberty.

Search for Associations of FSHR, INHA, INHAB, PRL, TNP2 and SPEF2 Genes Polymorphisms with Semen Quality in Russian Holstein Bulls (Pilot Study)

The aim of the study was to search for new mutations in the previously studied gene loci of follicle-stimulating hormone receptor (FSHR), inhibin α (INHA), inhibin β A (INHAB), prolactin (PRL), transition protein 2 (TNP2), and sperm flagella 2 (SPEF2) by sequencing, as well as the search for associations of previously identified mutations at these loci with fresh semen quality in Russian Holstein bulls. Phenotypic data from 189 bulls was collected. Data was analyzed for most bulls for three years of semen collection. The maximum value of each semen quality indicator (doublet ejaculate volume, sperm concentration, progressive motility and total number of spermatozoa) were selected. SNPs were identified in the FSHR, INHA, INHAB, TNP2, SPEF2 genes. The PRL gene did not have polymorphism. Significant (p < 0.05) associations of polymorphisms in the FSHR gene with double ejaculate volume, concentration and total number of spermatozoa were identified. Polymorphism in the INHA gene was significantly associated (p < 0.05) with sperm concentration. Polymorphism in the INHAB gene was significantly associated (p < 0.05) with doublet ejaculate volume and total number of spermatozoa. Polymorphisms in the TNP2 and SPEF2 genes did not have significant associations with semen quality. The SNPs studied in our pilot work may be considered as candidate genetic markers in the selection of bulls.

Effects of Environmental and Pathological Hypoxia on Male Fertility

Male infertility is a widespread health problem affecting approximately 6%-8% of the male population, and hypoxia may be a causative factor. In mammals, two types of hypoxia are known, including environmental and pathological hypoxia. Studies looking at the effects of hypoxia on male infertility have linked both types of hypoxia to poor sperm quality and pregnancy outcomes. Hypoxia damages testicular seminiferous tubule directly, leading to the disorder of seminiferous epithelium and shedding of spermatogenic cells. Hypoxia can also disrupt the balance between oxidative phosphorylation and glycolysis of spermatogenic cells, resulting in impaired self-renewal and differentiation of spermatogonia, and failure of meiosis. In addition, hypoxia disrupts the secretion of reproductive hormones, causing spermatogenic arrest and erectile dysfunction. The possible mechanisms involved in hypoxia on male reproductive toxicity mainly include excessive ROS mediated oxidative stress, HIF-1α mediated germ cell apoptosis and proliferation inhibition, systematic inflammation and epigenetic changes. In this review, we discuss the correlations between hypoxia and male infertility based on epidemiological, clinical and animal studies and enumerate the hypoxic factors causing male infertility in detail. Demonstration of the causal association between hypoxia and male infertility will provide more options for the treatment of male infertility.

Effect of gallic acid on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii)

Gallic acid (GA), a phenol that is present in various plants, potentially contains antioxidant properties. This study aimed to investigate the effects of GA on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii (Radde, 1861)). Antioxidant levels and apoptosis in the testis, as well as reproductive physiology, were evaluated in adolescent males treated with GA. The results showed that a low dose of GA enhanced relative epididymis mass and the sperm density in the epididymis, increased the mRNA levels of steroidogenic acute regulatory protein in the testis, and reduced the percentages of abnormal and dead sperm. In addition, a low dose of GA significantly increased the levels of superoxide dismutase, catalase, and glutathione peroxidase, and decreased the level of malondialdehyde in the testis, as well as the mRNA and protein levels of the apoptosis-related gene, caspase-3. However, a high dose of GA sharply reduced the mean diameter of the seminiferous tubules compared with a low dose. Collectively, these findings demonstrate that GA treatment during puberty affects the reproductive responses of male Brandt’s voles in a dose-dependent manner by regulating antioxidant levels and apoptosis.

Functional characterization of naturally-occurring constitutively activating/inactivating mutations in equine follicle-stimulating hormone receptor (eFSHR)

Objective

Follicle-stimulating hormone (FSH) is the central hormone involved in mammalian reproduction, maturation at puberty, and gamete production that mediates its function by control of follicle growth and function. The present study investigated the mutations involved in the regulation of FSH receptor (FSHR) activation.

Methods

We analyzed seven naturally-occurring mutations that were previously reported in human FSHR (hFSHR), in the context of equine FSHR (eFSHR); these include one constitutively activation variant, one allelic variant, and five inactivating variants. These mutations were introduced into wild-type eFSHR (eFSHR-wt) sequence to generate mutants that were designated as eFSHR-D566G, -A306T, -A189V, -N191I, -R572C, -A574V, and -R633H. Mutants were transfected into PathHunter EA-parental CHO-K1 cells expressing β-arrestin. The biological function of mutants was analyzed by quantitating cAMP accumulation in cells incubated with increasing concentrations of FSH.

Results

Cells expressing eFSHR-D566G exhibited an 8.6-fold increase in basal cAMP response, as compared to that in eFSHR-wt. The allelic variation mutant eFSHR-A306T was not found to affect the basal cAMP response or EC50 levels. On the other hand, eFSHR-D566G and eFSHR-A306T displayed a 1.5- and 1.4-fold increase in the maximal response, respectively. Signal transduction was found to be completely impaired in case of the inactivating mutants eFSHR-A189V, -R572C, and -A574V. When compared with eFSHR-wt, eFSHR-N191I displayed a 5.4-fold decrease in the EC50 levels (3910 ng/mL) and a 2.3-fold decrease in the maximal response. In contrast, cells expressing eFSHR-R633H displayed in a similar manner to that of the cells expressing the eFSHR-wt on signal transduction and maximal response.

Conclusion

The activating mutant eFSHR-D566G greatly enhanced the signal transduction in response to FSH, in the absence of agonist treatment. We suggest that the state of activation of the eFSHR can modulate its basal cAMP accumulation.

Testicular ultrasound inhomogeneity is an informative parameter for fertility evaluation

Testicular volume (TV) is proposed to be a positive predictor of male fertility status, because of the relation known between the TV and the seminiferous tubule content. Independently of the measurement methodology, the role of TV and testicular ultrasound (US) assessments is still debated in andrological clinical practice. In this retrospective cohort study, we evaluated TV and testis US role in the diagnostic workup of andrological patients. All consecutive outpatients undergoing single-operator testis US (Modena, Italy) from March 2012 to March 2018 were enrolled, matching sonographic, hormonal, and seminal data. A total of 302 men were referred and evaluated for gynecomastia, suspected hypogonadism, couple infertility (CI), or sexual dysfunction. In the hypogonadal group, TV was lower compared to that in other groups (P < 0.001), and a significant, direct correlation between TV and testosterone level was observed in nonandrogen-treated patients (R = 0.911, P < 0.001), suggesting that testicular size could be related to the testosterone-secreting compartment. In the CI group, normozoospermic patients showed higher TV compared to men with impaired semen quality (P = 0.003) and azoospermia (P = 0.003). However, TV was not able to discriminate between patients presenting normal and altered semen quality. On the contrary, testis US inhomogeneity was more frequent in patients with impaired sperm quality (55.0%; P = 0.007) and azoospermia (40.0%; P = 0.012), compared to patients with normozoospermia (5%), identifying thereby the sonographic pattern as an informative parameter of the fertility status. Therefore, in the CI workup, US evaluation seems to be more informative than the TV assessment alone.

Development of a Highly Sensitive ELISA for Measurement of FSH in Serum, Plasma, and Whole Blood in Mice

Follicle-stimulating hormone (FSH) regulates gonadal function and fertility. Measurement of FSH in bodily fluids and tissues is possible with radioimmunoassays and enzyme-linked immunosorbent assays (ELISAs). Recently, several novel assays were developed to measure pituitary hormones including growth hormone, prolactin, and luteinizing hormone in mice from small sample volumes. Here, we describe a novel and sensitive ELISA that enables the accurate measurement of FSH in serum, plasma, and whole blood from female and male mice. The assay can also be used to measure FSH in murine pituitary lysates and cell culture media. In summary, the new methodology described here will enable investigators to measure FSH from a variety of biological samples in mice accurately, at low cost, and in their own laboratories.

Basonuclin 1 deficiency causes testicular premature aging: BNC1 cooperates with TAF7L to regulate spermatogenesis

Basonuclin (BNC1) is expressed primarily in proliferative keratinocytes and gametogenic cells. However, its roles in spermatogenesis and testicular aging were not clear. Previously we discovered a heterozygous BNC1 truncation mutation in a premature ovarian insufficiency pedigree. In this study, we found that male mice carrying the truncation mutation exhibited progressively fertility loss and testicular premature aging. Genome-wide expression profiling and direct binding studies (by chromatin immunoprecipitation sequencing) with BNC1 in mouse testis identified several spermatogenesis-specific gene promoters targeted by BNC1 including kelch-like family member 10 (Klhl10), testis expressed 14 (Tex14), and spermatogenesis and centriole associated 1 (Spatc1). Moreover, biochemical analysis showed that BNC1 was associated with TATA-box binding protein-associated factor 7 like (TAF7L), a germ cell-specific paralogue of the transcription factor IID subunit TAF7, both in vitro and in testis, suggesting that BNC1 might directly cooperate with TAF7L to regulate spermatogenesis. The truncation mutation disabled nuclear translocation of the BNC1/TAF7L complex, thus, disturbing expression of related genes and leading to testicular premature aging. Similarly, expressions of BNC1, TAF7L, Y-box-binding protein 2 (YBX2), outer dense fiber of sperm tails 1 (ODF1), and glyceraldehyde-3-phosphate dehydrogenase, spermatogenic (GAPDHS) were significantly decreased in the testis of men with non-obstructive azoospermia. The present study adds to the understanding of the physiology of male reproductive aging and the mechanism of spermatogenic failure in infertile men.

Hormonal Treatment of Men with Nonobstructive Azoospermia: What Does the Evidence Suggest?

Hormonal stimulation of spermatogenesis prior to surgery has been tested by some authors to maximize the sperm retrieval yield in patients with nonobstructive azoospermia. Although the rationale of such an approach is theoretically sound, studies have provided conflicting results, and there are unmet questions that need to be addressed. In the present narrative review, we reviewed the current knowledge about the hormonal control of spermatogenesis, the relationship between presurgical serum hormones levels and sperm retrieval rates, and the results of studies investigating the effect of hormonal treatments prior to microdissection testicular sperm extraction. We pooled the available data about sperm retrieval rate in patients with low vs. normal testosterone levels, and found that patients with normal testosterone levels had a significantly higher chance of successful sperm retrieval compared to those with subnormal T levels (OR 1.63, 95% CI 1.08–2.45, p = 0.02). These data suggest that hormonal treatment may be justified in patients with hypogonadism; on the other hand, the available evidence is insufficient to recommend hormonal therapy as standard clinical practice to improve the sperm retrieval rate in patients with nonobstructive azoospermia.

Biased signaling in naturally occurring mutations of G protein-coupled receptors associated with diverse human diseases

G protein-coupled receptors (GPCRs) play critical roles in transmitting a variety of extracellular signals into the cells and regulate diverse physiological functions. Naturally occurring mutations that result in dysfunctions of GPCRs have been known as the causes of numerous diseases. Significant progresses have been made in elucidating the pathophysiology of diseases caused by mutations. The multiple intracellular signaling pathways, such as G protein-dependent and β-arrestin-dependent signaling, in conjunction with recent advances on biased agonism, have broadened the view on the molecular mechanism of disease pathogenesis. This review aims to briefly discuss biased agonism of GPCRs (biased ligands and biased receptors), summarize the naturally occurring GPCR mutations that cause biased signaling, and propose the potential pathophysiological relevance of biased mutant GPCRs associated with various endocrine diseases.

The Molecular Mechanism of Sex Hormones on Sertoli Cell Development and Proliferation

Sustaining and maintaining the intricate process of spermatogenesis is liable upon hormones and growth factors acting through endocrine and paracrine pathways. The Sertoli cells (SCs) are the major somatic cells present in the seminiferous tubules and are considered to be the main regulators of spermatogenesis. As each Sertoli cell supports a specific number of germ cells, thus, the final number of Sertoli cells determines the sperm production capacity. Similarly, sex hormones are also major regulators of spermatogenesis and they can determine the proliferation of Sertoli cells. In the present review, we have critically and comprehensively discussed the role of sex hormones and some other factors that are involved in Sertoli cell proliferation, differentiation and maturation. Furthermore, we have also presented a model of Sertoli cell development based upon the recent advancement in the field of reproduction. Hence, our review article provides a general overview regarding the sex hormonal pathways governing Sertoli cell proliferation and development.

Eight Days of Water-Only Fasting Promotes Favorable Changes in the Functioning of the Urogenital System of Middle-Aged Healthy Men

The aim of this study was to determine whether, after 8 days of water-only fasting, there are changes in the efficiency of the lower urinary tract, the concentration of sex hormones, and the symptoms of prostate diseases in a group of middle-aged men (n = 14). For this purpose, before and after 8 days of water-only fasting (subjects drank ad libitum moderately mineralized water), and the following somatic and blood concentration measurements were made: total prostate specific antigen (PSA-T), free prostate specific antigen (PSA-F), follicle stimulating hormone (FSH), luteotropic hormone (LH), prolactin (Pr), total testosterone (T-T), free testosterone (T-F), dehydroepiandrosterone (DHEA), sex hormone globulin binding (SHGB), total cholesterol (Ch-T), β-hydroxybutyrate (β-HB). In addition, prostate volume (PV), volume of each testis (TV), total volume of both testes (TTV), maximal urinary flow rate (Qmax), and International Prostate Symptom Score (IPSS) values were determined. The results showed that after 8 days of water-only fasting, Qmax and IPSS improved but PV and TTV decreased significantly. There was also a decrease in blood levels of PSA-T, FSH, P, T-T, T-F, and DHEA, but SHGB concentration increased significantly. These results indicate that 8 days of water-only fasting improved lower urinary tract functions without negative health effects.

Delayed and Precocious Puberty: Genetic Underpinnings and Treatments

Delayed puberty may signify a common variation of normal development, or indicate the presence of a pathologic process. Constitutional delay of growth and puberty is a strongly familial type of developmental pattern and accounts for the vast majority of children who are "late bloomers." Individuals with sex chromosomal abnormalities frequently have hypergonadotropic hypogonadism. There are currently 4 known monogenic causes of central precocious puberty. The primary treatment goal in children with hypogonadism is to mimic normal pubertal progression, while the primary aims for the management of precocious puberty are preservation of height potential and prevention of further pubertal development.

Murine FSH Production Depends on the Activin Type II Receptors ACVR2A and ACVR2B

Activins are selective regulators of FSH production by pituitary gonadotrope cells. In a gonadotrope-like cell line, LβT2, activins stimulate FSH via the activin type IIA receptor (ACVR2A) and/or bone morphogenetic protein type II receptor (BMPR2). Consistent with these observations, FSH is greatly reduced, though still present, in global Acvr2a knockout mice. In contrast, FSH production is unaltered in gonadotrope-specific Bmpr2 knockout mice. In light of these results, we questioned whether an additional type II receptor might mediate the actions of activins or related TGF-β ligands in gonadotropes. We focused on the activin type IIB receptor (ACVR2B), even though it does not mediate activin actions in LβT2 cells. Using a Cre-lox strategy, we ablated Acvr2a and/or Acvr2b in murine gonadotropes. The resulting conditional knockout (cKO) animals were compared with littermate controls. Acvr2a cKO (cKO-A) females were subfertile (~70% reduced litter size), cKO-A males were hypogonadal, and both sexes showed marked decreases in serum FSH levels compared with controls. Acvr2b cKO (cKO-B) females were subfertile (~20% reduced litter size), cKO-B males had a moderate decrease in testicular weight, but only males showed a significant decrease in serum FSH levels relative to controls. Simultaneous deletion of both Acvr2a and Acvr2b in gonadotropes led to profound hypogonadism and FSH deficiency in both sexes; females were acyclic and sterile. Collectively, these data demonstrate that ACVR2A and ACVR2B are the critical type II receptors through which activins or related TGF-β ligands induce FSH production in mice in vivo.

Use of Biosimilar Follicle-Stimulating Hormone in Asthenozoospermic Infertile Patients: A Multicentric Study

There is increasing data in favour of follicle-stimulating hormone (FSH) therapy in patients with oligo-asthenozoospermia and normal-range gonadotropins in order to increase sperm count and above all sperm motility. Some studies showed an improvement in DNA fragmentation and spontaneous pregnancy. Recently, biosimilar FSH has been marketed with the same indications. We performed a retrospective multicentric case-control study involving 147 asthenozoospermic patients between 18 and 45 years of age. A total of 97 patients were treated with biosimilar FSH 150 UI three times a week for 3 months, while 50 control subjects received no treatment. Patients were evaluated at baseline and after 3 months with semen analysis including DNA fragmentation, testicular colour Doppler ultrasound, and blood tests. Spontaneous pregnancies were recorded during a further follow-up period of 6 months. Treated patients showed after treatment a statistically significant increase in sperm concentration, total sperm count, and total motile sperm, as well as improved progressive motility and non-progressive motility. DNA fragmentation showed a significant reduction. Conversely, in the control group, no significant change was found. Pregnancy rate was significantly higher in treated patients. These data suggest comparable efficacy of biosimilar FSH in the treatment of male infertility; however, larger studies are needed to confirm our results.

Follicle-stimulating Hormone (FSH) Action on Spermatogenesis: A Focus on Physiological and Therapeutic Roles

BACKGROUND

Human reproduction is regulated by the combined action of the follicle-stimulating hormone (FSH) and the luteinizing hormone (LH) on the gonads. Although FSH is largely used in female reproduction, in particular in women attending assisted reproductive techniques to stimulate multi-follicular growth, its efficacy in men with idiopathic infertility is not clearly demonstrated. Indeed, whether FSH administration improves fertility in patients with hypogonadotropic hypogonadism, the therapeutic benefit in men presenting alterations in sperm production despite normal FSH serum levels is still unclear. In the present review, we evaluate the potential pharmacological benefits of FSH administration in clinical practice.

METHODS

This is a narrative review, describing the FSH physiological role in spermatogenesis and its potential therapeutic action in men.

RESULTS

The FSH role on male fertility is reviewed starting from the physiological control of spermatogenesis, throughout its mechanism of action in Sertoli cells, the genetic regulation of its action on spermatogenesis, until the therapeutic options available to improve sperm production.

CONCLUSION

FSH administration in infertile men has potential benefits, although its action should be considered by evaluating its synergic action with testosterone, and well-controlled, powerful trials are required. Prospective studies and new compounds could be developed in the near future.

New frontiers in fertility preservation: a hypothesis on fertility optimization in men with hypergonadotrophic hypogonadism

Strategies exist that can mitigate the risk of causing iatrogenic infertility when men require testosterone replacement therapy (TRT). This article reviews the current medical therapies that preserve spermatogenesis when TRT is indicated. Furthermore, we highlight the re-emerging concept of hypothalamic-pituitary-gonadal (HPG) axis reset in hypergonadotrophic, hypogonadal infertile men who are planning sperm retrieval procedures. Finally, we present our hypothesis for a novel protocol to optimize hypergonadotrophic hypogonadal men before sperm extraction surgeries hormonally.

Neuroendocrine, autocrine, and paracrine control of follicle-stimulating hormone secretion

Follicle-stimulating hormone (FSH) is a glycoprotein hormone produced by gonadotropes in the anterior pituitary that plays a central role in controlling ovarian folliculogenesis and steroidogenesis in females. Moreover, recent studies strongly suggest that FSH exerts extragonadal actions, particularly regulating bone mass and adiposity. Despite its crucial role, the mechanisms regulating FSH secretion are not completely understood. It is evident that hypothalamic, ovarian, and pituitary factors are involved in the neuroendocrine, paracrine, and autocrine regulation of FSH production. Large animal models, such as the female sheep, represent valuable research models to investigate specific aspects of FSH secretory processes. This review: (i) summarizes the role of FSH controlling reproduction and other biological processes; (ii) discusses the hypothalamic, gonadal, and pituitary regulation of FSH secretion; (iii) considers the biological relevance of the different FSH isoforms; and (iv) summarizes the distinct patterns of FSH secretion under different physiological conditions.

Use of follicle-stimulating hormone for the male partner of idiopathic infertile couples in Italy: Results from a multicentre, observational, clinical practice survey

BACKGROUND

The management of male idiopathic infertility is heterogeneous. Although meta-analyses reported the effectiveness on pregnancy rate, the real clinical impact of follicle-stimulating hormone (FSH) was not evaluated so far. In Italy, FSH is approved by the National Medicines Agency (AIFA) for idiopathic infertile patients with FSH < 8 IU/L, independently of semen parameters.

AIM

Primary endpoint was to record the therapeutic approach to the male partner of infertile couples. Secondary aim was to assess changes of semen parameters during FSH treatment.

METHODS

A multicentre, prospective, observational, clinical practice survey was carried out, enrolling the male partner of infertile couples attending ten Italian participating centres. Inclusion criteria were as follows: couple infertility, age >18 years and FSH serum levels <8 IU/L. Thus, all men in which AIFA allowed the FSH prescription were enrolled. Primary endpoint was the number of infertile patients treated with FSH. Secondary outcomes were semen parameters. The treating physician decided whether to offer FSH therapy and whether to re-evaluate the male partner.

RESULTS

A total of 718 infertile couples were enrolled, and 241 patients were re-evaluated (median follow-up: 4.5 months). In 64.9% (466 patients), a treatment was prescribed. FSH was prescribed in 397 patients (85.2% of treated men). Sperm concentration (P = .002) and normal form percentage (P < .001) significantly improved during FSH administration. No correlation was found between these parameters and FSH duration (P = .545 and P = .627, respectively) or dosage (P = .455 and P = .533, respectively). Among patients treated with FSH, the incidence of oligozoospermia decreased from 73.0% to 56.0% (P < .001) and teratozoospermia from 43.6% to 27.7% (P < .001).

DISCUSSION

This first nation-wide survey reveals a FSH prescription rate of 55% in patients qualifying for treatment according to AIFA. Although the study was not designed to highlight FSH efficacy in male infertility, a slight increase in semen parameters was demonstrated in about half of the treated men without adverse events.