Astrogenesis in the hypothalamus: A life-long process contributing to the development and plasticity of neuroendocrine networks.

Astrocytes are now recognized as integral components of neural circuits, regulating their maturation, activity and plasticity. Neuroendocrinology has provided fertile ground for revealing the diverse strategies used by astrocytes to regulate the physiological and behavioural outcomes of neural circuit activity in response to internal and environmental inputs. However, the development of astrocytes in the hypothalamus has received much less attention than in other brain regions such as the cerebral cortex and spinal cord. In this review, we synthesize our current knowledge of astrogenesis in the hypothalamus across various life stages. A distinctive feature of hypothalamic astrogenesis is that it persists all throughout lifespan, and involves multiple cellular sources corresponding to radial glial cells during early development, followed by tanycytes, parenchymal progenitors and locally dividing astrocytes. Astrogenesis in the hypothalamus is closely coordinated with the maturation of hypothalamic neurons. This coordination is exemplified by recent findings in neurons producing gonadotropin-releasing hormone, which actively shape their astroglial environment during infancy to integrate functionally into their neural network and facilitate sexual maturation, a process vulnerable to endocrine disruption. While hypothalamic astrogenesis shares common principles with other brain regions, it also exhibits specific features in its dynamics and regulation, both at the inter- and intra-regional levels. These unique properties emphasize the importance of further exploration. Additionally, we discuss the experimental strategies used to assess astrogenesis in the hypothalamus and their potential bias and limitations. Understanding the mechanisms of hypothalamic astrogenesis throughout life will be crucial for comprehending the development and function of the hypothalamus under both physiological and pathological conditions.

Quantification of urinary gonadotropins by specific assays may improve the evaluation of sex-specific hormonal changes in early infancy.

OBJECTIVE: The aim of this study was to investigate the feasibility of different gonadotropin assays for determining total and intact luteinizing hormone (LH), and follicle-stimulating hormone (FSH) immunoreactivity in urine (U-LH-ir and U-FSH-ir, respectively) during early infancy. DESIGN, PATIENTS AND MEASUREMENTS: Morning urine samples were obtained from 31 infants, aged between 0 and 6 months, to study the age-related course of urinary gonadotropins. Additionally, we investigated bi-hourly urine samples of a 5-day-old male neonate for 24 h to observe the course of urinary gonadotropins during a daily cycle. We employed different immunofluorometric assays for measuring total and intact U-LH-ir, and U-FSH-ir. RESULTS: In neonates up to 21 days of age, the U-LH-ir levels measured by the regular LH assay (also detecting hCG) were significantly higher than those determined by the total (specific) LH assays (p = .004). U-FSH-ir was higher in girls than boys during both the first and the next 5 months (p = .02 and p < .001, respectively), whereas total U-LH-ir was higher in boys until 6 months of age (p < .001). Total U-LH-ir/U-FSH-ir ratio was significantly higher in boys than girls across the first half-year (p < .001). CONCLUSIONS: The assessment of total U-LH-ir and U-FSH-ir, and their respective ratio constitutes a noninvasive, practical and scalable tool to investigate sex-specific changes during early infancy, with the ratio being significantly higher in boys than girls. Only highly specific LH assays detecting beta-subunit and its core fragment in addition to intact LH should be used for determining U-LH-ir in the neonatal period to avoid potential cross-reactivity with hCG of placental origin.

Anti-Mullerian hormone and spontaneous puberty in a diverse US Turner syndrome clinic cohort: A cross-sectional study.

OBJECTIVE: Serum Anti-Mullerian Hormone (AMH) concentrations have been proposed as a marker of spontaneous puberty and future fertility in Turner syndrome (TS). Gonadotropins during minipuberty may also provide a clue to ovarian function but there is insufficient data to inform utility in the routine clinical management of TS. Our objective was to describe the distribution of AMH in a cross-sectional cohort of patients in a TS specialty clinic, and correlate with spontaneous puberty and karyotype, as well as gonadotropins during the minipuberty of infancy in a smaller subset of patients aged 2-9 months. DESIGN: Retrospective chart review of patients seen in the TS clinic at Children's National Hospital from 1/1/2019 to 8/24/2022, to assess AMH and correlate with karyotype and spontaneous puberty. RESULTS: Among 114 patients (median age 9.6 year, 0.08-22 year), AMH values were detectable in only (40/104) 38%, and higher mean AMH (2.7 ± 0.95 ng/mL) was seen in mosaic 45,X/46,XX karyotype compared to 45,X (0.03 ± 0.14 ng/mL) (p < .001), and structurally abnormal-X karyotype (0.11 ± 0.5) (p = .0003). Mean AMH was higher (1.4 ± 1.6 ng/mL) among those with spontaneous menarche compared with spontaneous thelarche but no menarche. AMH was detectable in 2/10 during minipuberty in those with the lowest luteinizing hormone (LH). CONCLUSIONS: Our institutional data reflects a diverse cohort of patients seen in a TS specialty clinic in the United States, showing correlation of AMH with karyotype and spontaneous menarche, as well as description of gonadotropins during minipuberty highlighting their clinical relevance. Studies in larger, prospective longitudinal cohorts will help determine their predictive value and role in the care of TS.

Cohort profile: The Copenhagen Analgesic Study-The COPANA cohort.

BACKGROUND: Development of the gonads during fetal life is complex and vital for adult reproductive health. Cell and animal studies have shown an alarming effect of mild analgesics on germ cells in both males and females. More than 50% of pregnant women use mild analgesics during pregnancy, which potentially could compromise the reproductive health of the next generation. OBJECTIVES: We present a research protocol designed to evaluate the effect of prenatal exposure to mild analgesics and endocrine-disrupting chemicals on gonadal function in the offspring. POPULATION: Healthy, singleton pregnant women and their partners. DESIGN: The COPANA cohort is a prospective, observational pregnancy and birth cohort. METHODS: Participants were enrolled during the first trimester of pregnancy. Information on the use of mild analgesics was collected retrospectively 3 months prior to pregnancy and prospectively every 2 weeks throughout the study. We collected extensive data on lifestyle and reproductive health. Biospecimens were collected in the first trimester (maternal and paternal urine- and blood samples), in the third trimester in conjunction with a study-specific ultrasound scan (maternal urine sample), and approximately 3 months post-partum during the infant minipuberty period (maternal and infant urine- and blood samples). A comprehensive evaluation of reproductive function in the infants during the minipuberty phase was performed, including an ultrasound scan of the testis or ovaries and uterus. PRELIMINARY RESULTS: In total, 685 pregnant women and their partners were included between March 2020 and January 2022. A total of 589 infants (287 males) and their parents completed the follow-up during the minipuberty phase (December 2020-November 2022). CONCLUSIONS: The Copenhagen Analgesic Study holds the potential to provide novel and comprehensive insights into the impact of early and late prenatal exposure to mild analgesics and other endocrine-disrupting chemicals on future reproductive function in the offspring.

Development of external genitalia during mini-puberty: is it related to somatic growth or reproductive hormones?

Although hypothalamo-pituitary-gonadal axis is active during mini-puberty, its relationship with somatic growth and the role on the development of external genitalia has not been fully elucidated. We aimed to evaluate the effects of somatic growth and reproductive hormones on the development of external genitalia during mini-puberty. Anthropometric data, pubertal assesment, serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), dehydroepiandrosterone sulfate (DHEAS), androstenedione (A4), sex-hormone binding globulin (SHBG), estradiol (E2) and inhibin-B, testosterone (T), and anti-Mullerian Hormone (AMH) of healthy infants aged 1-4 months were evaluated. Free sex hormone index was calculated as T/SHBG for boys and E2/SHBG for girls. The mean age of 148 (74 female) infants included in the study was 2.31 ± 0.76 months. Tanner stage 2-3 sex steroid and gonadotropin levels were observed. A statistically significant difference was found between the weight, height, BMI, weight gain and serum FSH, LH, and A4 measurements of girls and boys (p < 0.05). Penile length was associated with weight (r = 0.24, p = 0.03), height (r = 0.25, p = 0.02), and AMH (r = 0.3, p = 0.01), but not with testosterone (p = 0.56 respectively). A negative correlation was found between weight and serum LH (r = - 0.26, p = 0.2) and T/SHBG levels in males (r = - 0.38, p = 0.015 respectively). Weight-SDS was negatively correlated with testosterone in males (r = - 0.25, p = 0.02). Testicular size and breast stage did not correlate with any of the hormonal and anthropometric parameters.  Conclusions: External genitalia in males during mini-puberty is related more to somatic growth rather than reproductive hormones. Similar to pubertal developmental stages, both total and free testosterone are negatively associated with higher weight during mini-puberty. What is Known: • Mini-puberty allows early assessment of HPG axis function in infancy. • There is an inverse relationship between the amount of adipose tissue and circulating testosterone levels in males during puberty and adulthood. • The potential effect of somatic growth and reproductive hormones on external genital development during mini-puberty remains unclear. What is New: • During mini-puberty, males' external genitalia is more related to somatic growth than to reproductive hormones, but this relationship is not observed in girls. • Both total and free testosterone are negatively associated with higher weight during mini-puberty, similar to the pubertal developmental stages.

Mechanistic screening of reproductive toxicity in a novel 3D testicular co-culture model shows significant impairments following exposure to low-dibutyl phthalate concentrations.

To improve the mechanistic screening of reproductive toxicants in  chemical-risk assessment and drug development, we have developed a three-dimensional (3D) heterogenous testicular co-culture model from neonatal mice. Di-n-butyl phthalate (DBP), an environmental contaminant that can affect reproductive health negatively, was used as a model compound to illustrate the utility of the in vitro model. The cells were treated with DBP (1 nM to 100 µM) for 7 days. Automated high-content imaging confirmed the presence of cell-specific markers of Leydig cells (CYP11A1 +), Sertoli cells (SOX9 +), and germ cells (DAZL +). Steroidogenic activity of Leydig cells was demonstrated by analyzing testosterone levels in the culture medium. DBP induced a concentration-dependent reduction in testosterone levels and decreased the number of Leydig cells compared to vehicle control. The levels of steroidogenic regulator StAR and the steroidogenic enzyme CYP11A1 were decreased already at the lowest DBP concentration (1 nM), demonstrating upstream effects in the testosterone biosynthesis pathway. Furthermore, exposure to 10 nM DBP decreased the levels of the germ cell-specific RNA binding protein DAZL, central for the spermatogenesis. The 3D model also captured the development of the Sertoli cell junction proteins, N-cadherin and Zonula occludens protein 1 (ZO-1), critical for the blood-testis barrier. However, DBP exposure did not significantly alter the cadherin and ZO-1 levels. Altogether, this 3D in vitro system models testicular cellular signaling and function, making it a powerful tool for mechanistic screening of developmental testicular toxicity. This can open a new avenue for high throughput screening of chemically-induced reproductive toxicity during sensitive developmental phases.

Minipuberty period of children with atopic dermatitis compared to healthy children.

Background/aim: Atopic dermatitis (AD) is an inflammatory, pruritic, noncontagious, chronic relapsing skin disease. Skin barrier abnormalities, excessive T helper 2 activity, and immune dysregulation are held responsible. Androgens have a negative effect on the integrity of the epidermal skin barrier, while estrogen has a positive effect. We aimed to investigate whether hormones make a difference between healthy children and children with AD during minipuberty. Materials and methods: A total of 96 infants (postnatal 4-13 weeks), 48 diagnosed with AD and 48 controls, were included. Each group consisted of 23 girls (47.9%) and 25 boys (52.1%). Anthropometric examinations and hormone measurements were compared. Results: The two groups, having similar age, sex, body mass index, and weight-for-length standard deviation scores, were compared. Serum free thyroxine (FT4) levels were found to be lower and insulin-like growth factor binding protein-3 (IGFBP3) levels were found to be higher in children with AD (p < 0.001 and p = 0.038, respectively). In girls with AD, estradiol, FT4, and insulin-like growth factor-1 (IGF-1) levels were found to be lower, but thyroid-stimulating hormone (TSH) levels were found to be higher (p = 0.023, p < 0.001, p = 0.038, and p = 0.034, respectively). In boys with AD, the FT4 level was found to be lower (p = 0.023). Serum FT4 and TSH levels were within normal reference ranges in all comparisons. Conclusion: Especially in girls with AD, decreased estradiol and IGF-1 levels were observed compared to the controls during minipuberty. In the logistic regression model, decreased levels of serum estradiol, dehydroepiandrosterone sulfate, FT4, and IGF-1, and increased levels of IGFBP3 were associated with an increased likelihood of exhibiting atopic dermatitis.

Deciphering the Roles & Regulation of Estradiol Signaling during Female Mini-Puberty: Insights from Mouse Models.

Mini-puberty of infancy is a short developmental phase occurring in humans and other mammals after birth. In females, it corresponds to transient and robust activation of the hypothalamo-pituitary-ovarian (HPO) axis revealed by high levels of gonadotropin hormones, follicular growth, and increased estradiol production by the ovary. The roles of estradiol signaling during this intriguing developmental phase are not yet well known, but accumulating data support the idea that it aids in the implementation of reproductive function. This review aims to provide in-depth information on HPO activity during this particular developmental phase in several mammal species, including humans, and to propose emerging hypotheses on the putative effect of estradiol signaling on the development and function of organs involved in female reproduction.

Immunological interpretation of minipuberty: Minipuberty as the driving force of sexual dimorphism in the immune response.

BACKGROUND/OBJECTIVE: Although the physiology of minipuberty is well established, it is not fully explained why it occurs. It has been suggested that minipuberty contributes to the development of reproductive organs, somatic growth, cognitive/behavioural and sex-specific brain development. Given the well-known trade-off between the reproductive/endocrine and immune systems in adults, the immunological approach to minipuberty, which is characterized by transient activation of the hypothalamo-pituitary gonadal (HPG) axis, seems to be ignored. This study focused on the relationship of the lymphocyte subsets with gonadotrophin and sex hormones during the minipuberty. MATERIALS AND METHODS: A total of 121 newborns (58 male) were included in this cross-sectional study. The hormone and lymphocyte subsets studied were as follow: follicle-stimulating hormone (FSH), luteinizing hormone (LH) estradiol (E), testosterone (T), CD19, CD16/56, CD3, CD3/CD4, CD3/CD8 and HLA-DR as lymphocyte activation marker. RESULTS: The mean FSH levels were higher in females (15.15 ± 10.12 mIU/ml vs, 2.61 ± 1.74 mIU/ml) and LH in males (5.80 ± 2.51 mIU/ml vs. 1.91 ± 12.89 mIU/ml) (P < .001 for each). The mean percentages of the CD3/CD4 levels were higher in females (54.61 ± 6.70% vs. 51.17 ± 6.77%) and CD3/CD8 in males (21.49 ± 4.82% vs. 17.31 ± 3.66%) (P < .001 for each). In the females, the mean FSH levels negatively correlated with CD3/CD4 (rFSH-CD3/CD4  = -0.423, P = .001) and positively correlated with CD3/CD8 (rFSH-CD3/CD8  = 0.311, P = .013). In the males, LH positively correlated with CD3/CD4 (rLH-CD3/CD4  = 0.406, P < .001) and negatively correlated with CD3/CD8 (rLH-CD3/CD8  = -0.486, P < .001). CONCLUSION: This study showed that the mean CD3/CD4 levels were higher in female and CD3/CD8 in male newborns, indicating that there was a sexual dimorphism in favour of immunostimulant in females and immunosuppressor components of immune response in males during the minipuberty. These interactions point to sex-specific trade-off between reproductive/endocrine and immune systems, which it reflects the an investment favouring in the reproductive system against the immune response during minipuberty, which is critical period for adult fertility, especially in males.

SRY-negative 46,XX testicular/ovotesticular DSD: Long-term outcomes and early blockade of gonadotropic axis.

OBJECTIVE: SRY-negative 46,XX testicular and ovotesticular disorders/differences of sex development (T/OTDSD) represent a very rare and unique DSD condition where testicular tissue develops in the absence of a Y chromosome. To date, very few studies have described the phenotype, clinical and surgical management and long-term outcomes of these patients. Particularly, early blockade of the gonadotropic axis in patients raised in the female gender to minimize postnatal androgenization has never been reported. DESIGN: Retrospective description of sixteen 46,XX T/OTDSD patients. RESULTS: Sixteen 46,XX SRY-negative T/OTDSD were included. Most (12/16) were diagnosed in the neonatal period. Sex of rearing was male for six patients and female for ten, while the clinical presentation varied, with an external masculinization score from 1 to 10. Five patients raised as girl were successfully treated with GnRH analog to avoid virilization during minipuberty. Ovotestes/testes were found bilaterally for 54% of the patients and unilaterally for the others (with a contralateral ovary). Gonadal surgery preserved appropriate tissue in the majority of cases. Spontaneous puberty occurred in two girls and one boy, while two boys required hormonal induction of puberty. One of the girls conceived spontaneously and had an uneventful pregnancy. DNA analyses (SNP-array, next-generation sequencing and whole-exome sequencing) were performed. A heterozygous frameshit mutation in the NR2F2 gene was identified in one patient. CONCLUSIONS: This study presents a population of patients with 46,XX SRY-negative T/OTDSD. Early blockade of gonadotropic axis appears efficient to reduce and avoid further androgenization in patients raised as girls.

Characterization of ovarian development in girls from birth to 9 months.

BACKGROUND: The minipuberty of infancy is a period of increased reproductive axis activity. Changes in reproductive hormone concentrations and organ size occur during this period, but longitudinal changes have not been well described. OBJECTIVES: The objective of this study was to characterize ovarian growth trajectories and ovarian follicle development during the first 9 months of life in a large longitudinal cohort of healthy girls. METHODS: Data from the Infant Feeding and Early Development Study, a longitudinal cohort study of oestrogen-responsive outcomes in healthy infants, were used to estimate ovarian growth trajectories and describe the presence of ovarian antral follicles in girls 0-9 months old. Ovarian ultrasound evaluations were performed on the infants within 72 hours of birth (newborn visit) and at 4, 8, 16, 24, and 32 weeks of age. Mixed-effects regression splines were used to characterize changes in ovarian volume during infancy and assess the association between the presence of ovarian follicles at the newborn visit and ovarian growth. RESULTS: This analysis included 163 girls with two or more ovarian ultrasounds in the study. Results from the estimated overall ovarian growth trajectory show that ovarian volume increases more than sixfold during the first 16 weeks after birth and then remains relatively stable in the later weeks of infancy. Among girls with observable ovaries at the newborn visit (n = 133), girls with at least one visible ovarian follicle showed more rapid initial ovarian growth compared with girls without visible follicles. CONCLUSIONS: Infant ovarian volume increased to a peak at 16 weeks, which was influenced by the number and size of developing follicles. This research contributes to future development of reference ranges for postnatal ovarian growth in healthy, term infants.

Cohort profile: The COPENHAGEN Minipuberty Study-A longitudinal prospective cohort of healthy full-term infants and their parents.

BACKGROUND: The hypothalamic-pituitary-gonadal (HPG) axis governs sexual maturation and reproductive function in humans. In early postnatal life, it is transiently active during which circulating sex steroids reach adult levels. While this so-called minipuberty represents a universal phenomenon in infants of both sexes, its role for early maturation and growth remains incompletely understood. OBJECTIVES: To provide normative data on auxology as well as serum and urinary hormone levels in healthy, full-term infants throughout the first year of life and to investigate associations of postnatal HPG axis dynamics as well as hormonal, genetic and environmental exposures with early genital development and growth. POPULATION: Healthy, Danish, full-term, singleton newborns including their parents. DESIGN: Single-centre, prospective, observational longitudinal pregnancy and birth cohort. METHODS: Newborns were followed with six repeated clinical examinations during a one-year follow-up period. An umbilical cord blood sample was drawn at birth. At each visit, infants underwent a clinical examination focusing on auxology and genital development. Further, blood (serum, plasma, DNA) and urine samples were collected at each visit. Mothers and fathers underwent a clinical examination and provided blood samples prior to and after birth. A subset of parents provided urine samples and breast milk samples. Pregnancy and obstetrical outcomes, and detailed parental questionnaires were compiled. PRELIMINARY RESULTS: Between August 2016 and August 2018, 2481 women with singleton pregnancies were invited to participate of which 298, including their partners, were enrolled (12.0%). A total of 268 healthy, full-term newborns born appropriate for gestational age (AGA) were included at birth, 233 newborns participated in the postnatal follow-up period and 186 completed the one-year follow-up period (9.4% and 7.5%, respectively). CONCLUSION: The COPENHAGEN Minipuberty Study provides detailed, longitudinal data on early genital development and growth including hormonal and genetic profiles and environmental exposure in healthy infants including additional data in their parents.

From mini-puberty to pre-puberty: early impairment of the hypothalamus-pituitary-gonadal axis with normal testicular function in children with non-mosaic Klinefelter syndrome.

PURPOSE: Klinefelter syndrome (KS) is a genetic disorder caused by the presence of an extra X chromosome in males. The aim of this study was to evaluate the hypothalamic-pituitary-gonadal (HPG) axis and the clinical profile of KS boys from mini-puberty to early childhood. PATIENTS AND METHODS: In this retrospective, cross-sectional, population study, 145 KS boys and 97 controls aged 0-11.9 years were recruited. Serum FSH, LH, testosterone (T), Inhibin B (INHB), sex hormone binding globulin (SHBG) and anti-Müllerian hormone (AMH) were determined. Auxological parameters were assessed. To better represent the hormonal and clinical changes that appear in childhood, the entire population was divided into 3 groups: ≤ 6 months (group 1; mini-puberty); > 6 months and ≤ 8 years (group 2; early childhood); > 8 and ≤ 12 years (group 3; mid childhood). RESULTS: During mini-puberty (group 1), FSH and LH were significantly higher in KS infants than controls (p < 0.05), as were INHB and T (respectively p < 0.0001 and p < 0.005). INHB was also significantly higher in KS than controls in group 2 (p < 0.05). AMH appeared higher in KS than in controls in all groups, but the difference was only statistically significant in group 2 (p < 0.05). No significant differences were found in height, weight, testicular volume, and penile length. CONCLUSIONS: No hormonal signs of tubular or interstitial damage were found in KS infants. The presence of higher levels of gonadotropins, INHB and testosterone during mini-puberty and pre-puberty may be interpreted as an alteration of the HPG axis in KS infants.

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 (LHß) 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.

Minipuberty in Klinefelter syndrome: Current status and future directions.

Klinefelter syndrome is highly underdiagnosed and diagnosis is often delayed. With the introduction of non-invasive prenatal screening, the diagnostic pattern will require an updated description of the clinical and biochemical presentation of infants with Klinefelter syndrome. In the first months of life, the hypothalamic-pituitary-gonadal (HPG)-axis is transiently activated in healthy males during the so-called minipuberty. This period represents a "window of opportunity" for evaluation of the HPG-axis before puberty and without stimulation tests. Infants with Klinefelter syndrome present with a hormonal surge during the minipuberty. However, only a limited number of studies exist, and the results are contradictory. Further studies are needed to clarify whether infants with Klinefelter syndrome present with impaired testosterone production during the minipuberty. The aim of this review is to describe the clinical and biochemical characteristics of the neonate and infant with Klinefelter syndrome with special focus on the minipuberty and to update the clinical recommendations for Klinefelter syndrome during infancy.

The role of gonadotrophins in gonocyte transformation during minipuberty.

PURPOSE: Postnatal surge of gonadotrophins, Luteinizing hormone (LH) and Follicle-Stimulating hormone (FSH) known as minipuberty, is critical for gonocyte maturation into spermatogonial stem cells (SSC) in the testis. Gonadotrophins are essential for optimum fertility in men, but very little is known how they regulate germ cells during minipuberty. This study examined whether gonadotrophins play a role on gonocyte transformation in vivo. METHODS: Testes from hypogonadal (hpg) mice and their wild type (WT) littermates (n = 6/group) were weighed, and processed in paraffin at postnatal days (D) 0, 3, 6 and 9. Mouse VASA homologue (germ cell marker), anti-Müllerian hormone (Sertoli cell marker) antibodies and DAPI (nuclei marker) were used for immunofluorescence followed by confocal imaging. Germ cells on or off basement membrane (BM) and Sertoli cells/tubule were counted using Image J and analyzed with GraphPad. RESULTS: Comparing to WT littermates, there were significantly fewer germ cells on BM/tubule (p < 0.05) in D9 hpg mice, whereas there was no significant difference for germ cells off BM/tubule and Sertoli cells/tubule between littermates. However, testicular weight was significantly reduced in D3-D9 hpg mice comparing to WT littermates. CONCLUSION: Gonadotrophin deficiency reduced D9 germ cells on BM indicating impaired gonocyte transformation into SSC. This suggests that gonadotrophins may mediate gonocyte transformation during minipuberty.

Evaluation of vitamin D status and its correlation with gonadal function in children at mini-puberty.

CONTEXT: The effects of Vitamin D on reproductive function in adults have gained interest. Studies have demonstrated some associations. Hypothalamic-pituitary-gonadal axis is activated during the first 6 months of life, called as mini-puberty. This HPG activation is important for future gonadal function. There are no data regarding the association of gonadal hormones and 25(OH)D levels at mini-puberty. Demonstration of any association would form the basis for studies that will search for the effects of 25(OH)D on gonadal hormones at mini-puberty. OBJECTIVE: To characterize the associations between 25(OH)D levels and gonadal hormones at mini-puberty. DESIGN: Cross-sectional cohort analysis. PATIENT(S) OR OTHER PARTICIPANT(S): A total of 180 (94 boys and 86 girls) healthy appropriate-for-gestational-age neonates were included. MAIN OUTCOME MEASURE(S): 25(OH)D, LH, FSH, total testosterone, oestradiol, AMH and inhibin B levels were measured at postnatal 30-45 days. All infants were divided into three groups including vitamin D deficiency (<10 ng/mL), vitamin D insufficiency (10-20 ng/mL) and vitamin D sufficiency (>20 ng/mL). Correlations between vitamin D status and reproductive hormones were analysed. RESULT(S): Total testosterone level was higher (mean: 0.52 ± 0.32 vs 0.26 ± 0.2 ng/mL; P: 0.008) and inhibin B was lower in 25(OH)D deficient than sufficient girls (mean: 21.2 ± 15.71 vs 53.25 ± 47.25 pg/mL; P: 0.021). CONCLUSION(S): A modest effect of 25(OH)D was identified on total testosterone and inhibin B in girls at mini-puberty. The 25(OH)D may have an effect on gonadal function during early life. Randomized controlled trials could clarify the importance of vitamin D on gonadal hormones at mini-puberty.

Genes Involved in Long-Term Memory Are Expressed in Testis of Cryptorchid Boys and Respond to GnRHa Treatment.

It has been known for many years that boys with unilateral or bilateral undescended testis (cryptorchidism) tend to have a low IQ, and those who belong to the high infertility risk (HIR) group perform less well at school than low infertility risk (LIR) patients. However, the molecular biological processes underlying this phenomenon are not understood. In this study, we report the outcome of testicular RNA profiling for genes involved in long-term memory formation. We analyzed the histology and the transcriptome of testicular biopsies from bilateral HIR cryptorchid boys, comparing those who received GnRHa treatment for 6 months after the first surgery with those who did not receive GnRHa before the second surgery. We found that GnRHa treatment alters the testicular mRNA levels of neuronal genes that are involved in long-term memory and testosterone synthesis. These data highlight a possible molecular link between cryptorchidism, impaired mini-puberty, and diminished cognitive functions. Our results are consistent with the hypothesis that hypogonadotropic hypogonadism in cryptorchid boys with altered mini-puberty may affect neuronal genes important for memory and learning, which could help explaining the negative correlation between cryptorchidism and intellectual abilities.

Genetic testing facilitates prepubertal diagnosis of congenital hypogonadotropic hypogonadism.

Neonatal micropenis and cryptorchidism raise the suspicion of congenital hypogonadotropic hypogonadism (CHH), a rare genetic disorder caused by gonadotropin-releasing hormone deficiency. Low plasma testosterone levels and low gonadotropins during minipuberty provide a clinical diagnostic clue, yet these tests are seldomly performed in general practice. We report a male neonate with no family history of reproductive disorders who was born with micropenis and cryptorchidism. Hormonal testing at age 2.5 months showed low testosterone (0.3 nmol/L) and undetectable gonadotropins (luteinizing hormone and follicle-stimulating hormone both <0.5 U/L), suggestive of CHH. Genetic testing identified a de novo, heterozygous mutation in fibroblast growth factor receptor 1 (FGFR1 p.L630P). L630 resides on the ATP binding cleft of the FGFR1 tyrosine kinase domain, and L630P is predicted to cause a complete loss of receptor function. Cell-based assays confirmed that L630P abolishes FGF8 signaling activity. Identification of a loss-of-function de novo FGFR1 mutation in this patient confirms the diagnosis of CHH, allowing for a timely hormonal treatment to induce pubertal development. Therefore, genetic testing can complement clinical and hormonal assessment for a timely diagnosis of CHH in childhood.