Patricia Bedecarrás

AMH/MIS: what we know already about the gene, the protein and its regulation

(AMH/MIS) was first suggested by Jost, more than Four decades before this gonadal glycoprotein was purified and its gene and promoter sequenced. In mammals, AMH expression is triggered by SOX9 in Sertoli cells at the onset of testicular differentiation, and regulated by SF1, GATA factors, WT1, DAX1 and FSH. Ovarian granulosa cells also secrete AMH from late foetal life. In males, AMH is secreted into the bloodstream at high levels until puberty when it is down-regulated by androgens and meiotic germ cells and its directional secretion switches from the basal compartment to the seminiferous tubule lumen. In birds and reptiles, AMH expression shows particular features. Serum AMH determination is useful to study testicular function in boys and in patients with gonadal tumours. AMH levels in seminal and follicular fluid may also be of clinical use.

Establishment of testicular endocrine function impairment during childhood and puberty in boys with Klinefelter syndrome.

Objective  To precisely characterize the chronology of testicular endocrine function impairment during childhood and adolescence in patients with Klinefelter syndrome.

SOX9 and SF1 are involved in cyclic AMP-mediated upregulation of anti-Müllerian gene expression in the testicular prepubertal Sertoli cell line SMAT1

In Sertoli cells, anti-Müllerian hormone (AMH) expression is upregulated by FSH via cyclic AMP (cAMP), although no classical cAMP response elements exist in the AMH promoter. The response to cAMP involves NF-κB and AP2; however, targeted mutagenesis of their binding sites in the AMH promoter do not completely abolish the response. In this work we assessed whether SOX9, SF1, GATA4, and AP1 might represent alternative pathways involved in cAMP-mediated AMH upregulation, using real-time RT-PCR (qPCR), targeted mutagenesis, luciferase assays, and immunocytochemistry in the Sertoli cell line SMAT1. We also explored the signaling cascades potentially involved. In qPCR experiments, Amh, Sox9, Sf1, and Gata4 mRNA levels increased after SMAT1 cells were incubated with cAMP. Blocking PKA abolished the effect of cAMP on Sox9, Sf1, and Gata4 expression, inhibiting PI3K/PKB impaired the effect on Sf1 and Gata4, and reducing MEK1/2 and p38 MAPK activities curtailed Gata4 increase. SOX9 and SF1 translocated to the nucleus after incubation with cAMP. Mutations of the SOX9 or SF1 sites, but not of GAT4 or AP1 sites, precluded the response of a 3,063-bp AMH promoter to cAMP. In conclusion, in the Sertoli cell line SMAT1 cAMP upregulates SOX9, SF1, and GATA4 expression and induces SOX9 and SF1 nuclear translocation mainly through PKA, although other kinases may also participate. SOX9 and SF1 binding to the AMH promoter is essential to increase the activity of the AMH promoter in response to cAMP.

Altered serum profile of inhibin B, Pro‐αC and anti‐Müllerian hormone in prepubertal and pubertal boys with varicocele

objective  Anti‐Müllerian hormone (AMH) and inhibin B are reliable markers of Sertoli cell function. The aim of the present study was to assess the functional state of Sertoli cells in order to detect early changes in the testicular function of prepubertal and pubertal patients with untreated grade II or III varicocele.

Gonadotrophin secretion pattern in anorchid boys from birth to pubertal age: pathophysiological aspects and diagnostic usefulness.

Context  The biphasic ontogeny of serum gonadotrophins observed in normal children also exists in girls with gonadal dysgenesis, although with higher levels. However, limited data exist in prepubertal boys with anorchia.

Sertoli cell markers in the diagnosis of paediatric male hypogonadism

Abstract During childhood, the pituitary-testicular axis is partially dormant: testosterone secretion decreases following a drop in luteinising hormone levels; follicle-stimulating hormone (FSH) levels also go down. Conversely, Sertoli cells are most active, as revealed by the circulating levels of anti-Müllerian hormone (AMH) and inhibin B. Therefore, hypogonadism can best be evidenced, without stimulation tests, if Sertoli cell function is assessed. Serum AMH is high from fetal life until mid-puberty. Testicular AMH production increases in response to FSH and is potently inhibited by androgens. Inhibin B is high in the first years of life, then decreases partially while remaining clearly higher than in females, and increases again at puberty. Serum AMH and inhibin B are undetectable in anorchid patients. In primary or central hypogonadism affecting the whole gonad established in fetal life or childhood, all testicular markers are low. Conversely, when hypogonadism only affects Leydig cells, serum AMH and inhibin B are normal. In males of pubertal age with central hypogonadism, AMH and inhibin B are low. Treatment with FSH provokes an increase in serum levels of both Sertoli cell markers, whereas human chorionic gonadotrophin (hCG) administration increases testosterone levels. In conclusion, measurement of serum AMH and inhibin B is helpful in assessing testicular function, without need for stimulation tests, and orientates the aetiological diagnosis of paediatric male hypogonadism.

Spreading the Clinical Window for Diagnosing Fetal-Onset Hypogonadism in Boys

In early fetal development, the testis secretes – independent of pituitary gonadotropins – androgens and anti-Müllerian hormone (AMH) that are essential for male sex differentiation. In the second half of fetal life, the hypothalamic–pituitary axis gains control of testicular hormone secretion. Follicle-stimulating hormone (FSH) controls Sertoli cell proliferation, responsible for testis volume increase and AMH and inhibin B secretion, whereas luteinizing hormone (LH) regulates Leydig cell androgen and INSL3 secretion, involved in the growth and trophism of male external genitalia and in testis descent. This differential regulation of testicular function between early and late fetal periods underlies the distinct clinical presentations of fetal-onset hypogonadism in the newborn male: primary hypogonadism results in ambiguous or female genitalia when early fetal-onset, whereas it becomes clinically undistinguishable from central hypogonadism when established later in fetal life. The assessment of the hypothalamic–pituitary–gonadal axis in male has classically relied on the measurement of gonadotropin and testosterone levels in serum. These hormone levels normally decline 3–6 months after birth, thus constraining the clinical evaluation window for diagnosing male hypogonadism. The advent of new markers of gonadal function has spread this clinical window beyond the first 6 months of life. In this review, we discuss the advantages and limitations of old and new markers used for the functional assessment of the hypothalamic–pituitary–testicular axis in boys suspected of fetal-onset hypogonadism.

Seminiferous tubule function in delayed-onset X-linked adrenal hypoplasia congenita associated with incomplete hypogonadotrophic hypogonadism.

Objective  X‐linked adrenal hypoplasia congenita (AHC, OMIM 300200) due to mutations in the DAX‐1 gene is frequently associated to hypogonadotrophic hypogonadism (HHG, OMIM 238320). Clinical variants with delayed‐onset have been recognized. The objective of this study is to assess Sertoli cell function throughout pubertal development in patients with childhood‐onset AHC due to stop mutations in the DAX‐1 gene.

Male Central Precocious Puberty: Serum Profile of Anti-Müllerian Hormone and Inhibin B before, during, and after Treatment with GnRH Analogue

We aimed to describe the functional changes of Sertoli cells, based on the measurement of serum anti-Müllerian hormone (AMH) and inhibin B during treatment with GnRHa and after its withdrawal in boys with central precocious puberty. Six boys aged 0.8 to 5.5 yr were included. AMH was low at diagnosis in patients >1 yr but within the normal range in younger patients. AMH increased to normal prepubertal levels during treatment. After GnRHa withdrawal, AMH declined concomitantly with the rise in serum testosterone. At diagnosis, inhibin B was elevated and decreased throughout therapy, remaining in the upper normal prepubertal range. In patients with testicular volume above 4 mL AMH remained higher in spite of suppressed FSH. After treatment withdrawal, inhibin B rose towards normal pubertal levels. In conclusion, AMH did not decrease in patients <1 yr reflecting the lack of androgen receptor expression in Sertoli cells in early infancy. Serum inhibin B might result from the contribution of two sources: the mass of Sertoli cells and the stimulation exerted by FSH. Sertoli cell markers might provide additional tools for the diagnosis and treatment followup of boys with central precocious puberty.

Compensatory function of the remaining testis is dissociated in boys and adolescents with monorchidism

OBJECTIVE Compensatory hypertrophy has been classically described in patients with monorchidism. However, it remains unclear whether there is a functional compensatory activity of the different cell populations. Our aim was to assess the functional capacity of the solitary testis in monorchid males from infancy through puberty in order to determine whether the remaining gonad is capable of compensating the functional activity of Sertoli and Leydig cells of the absent gonad. DESIGN In a retrospective, cross-sectional, analytical study performed at a tertiary paediatric public hospital, we included 89 boys with monorchidism and 358 healthy controls, aged 6 months-18 years. Testicular volume and circulating levels of reproductive hormones were compared between patients with monorchidism and normal boys. Serum anti-Müllerian hormone (AMH) and FSH were used as biomarkers of the functional mass of prepubertal Sertoli cells, whereas serum testosterone and LH were used as biomarkers of Leydig cells. RESULTS In the vast majority of the cases, the testicular volume of monorchid boys was smaller than the sum of the volume of both testes of healthy controls. Serum AMH was lower and FSH was higher in patients with monorchidism than in controls aged <3 and >13 years. Serum testosterone and LH did not differ significantly between patients and controls. CONCLUSION In boys and adolescents with monorchidism, there is a dissociated capacity of the remaining testis to compensate for the absence of the other gonad: while Leydig cell function is largely compensated, Sertoli cell proliferation and function was lower than in controls.