Molecular and Environmental Mechanisms Regulating Puberty Initiation: An Integrated Approach

Comparison of central precocious puberty frequency before and during COVID-19: a systematic review and meta-analysis

OBJECTIVE

The current systematic review and meta-analysis assessed the prevalence of central precocious puberty (CPP) throughout the novel coronavirus disease 2019 (COVID-19) pandemic.

DESIGN

A systematic review and meta-analysis were carried out following the principles outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA, 2020).

DATA SOURCES

PubMed, Embase, Web of Science, and WANFANG databases were searched from January 1, 2019, to March 30, 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

(1) children and adolescents ≤ 15 years; (2) studies with the outcome of frequency of central precocious puberty, measured prior to and throughout the COVID-19 pandemic; (3) a novel CPP diagnosis was created depending on all of the following criteria: girls with a chronological age < 8 years and boys with a chronological age < 9 years at the onset of symptoms, basal luteinizing hormone (LH) levels > 0.3 UI/L, and/or GnRH-stimulated peak LH levels > 5 IU/L.

DATA EXTRACTION AND SYNTHESIS

The process of extracting data and evaluating the likelihood of bias was carried out by two independent reviewers. The data were pooled employing the generic inverse-variance method and presented as mean differences (MDs) with 95% CIs. The evaluation of heterogeneity was conducted employing the Cochran Q statistic, and the degree of heterogeneity was measured employing the I2 statistic.

RESULTS

This meta-analysis included 17 studies. In contrast to the same period prior to the COVID-19 pandemic, the occurrence of CPP elevated (OR = 2.57; 95% CI, 1.85-3.56). Moreover, body mass index standard deviation score (BMI SDS) differences between CPP patients prior to COVID-19 and throughout the pandemic follow-up was 0.12 (95% CI - 0.01 to 0.25 P = 0.06).

CONCLUSION

Overall, CPP frequency significantly elevated throughout the COVID-19 pandemic. Given the restricted number of cohort investigations in this meta-analysis, additional research may be conducted on larger groups of children in order to establish a correlation between the observed rise in precocious puberty and specific pathogenic factors.

Associations between birth characteristics, pubertal timing and adult height

AIM

This study investigated the association between gestational age and birth size with pubertal timing, measured as peak height velocity, and adult height.

METHODS

This retrospective, population-based study was conducted in Sweden in 2023. A sub-group of the 1974 and 1990 GrowUp Gothenburg cohorts was used (n = 4700, 50% males). The subgroup consisted of healthy individuals with Nordic ethnicity, known parental heights and measured adult heights. Data on birth characteristics (gestational age, birth length, birth weight) were collected. Pubertal timing was assessed as age at peak height velocity. Univariable linear regression analysis and bivariate correlations were conducted to answer the research questions.

RESULTS

Gestational age was not associated with age at peak height velocity or adult height. Birth length and weight could explain 12% and 8% (p ≤ 0.001) respectively of attained adult height. However, birth length and birth weight could only explain the variation in age at peak height velocity to a small degree.

CONCLUSION

This study showed that gestational age is not associated with age at peak height velocity or adult height. A positive relationship was found between birth size, particularly birth length, and adult height. No strong associations were found between birth size and age at peak height velocity.

The Impact of Socioeconomic Status on Visual Acuity Changes in Schoolchildren: A One-Year Follow-Up

(1) Background: Visual acuity (VA) is essential for children's quality of life, and its relationship with socioeconomic status (SES) highlights disparities in healthcare. This study investigated the influence of SES on changes in schoolchildren's VA over one year. (2) Methods: Initial examinations were conducted on 1822 children (8-10 years). Follow-up was performed on 804 of these children a year later. Uncorrected (UCVA) and presenting (PVA) distance VA were measured monocularly using a decimal Snellen chart. Very reduced UCVA (<0.5) was considered a proxy of myopia. (3) Results: The prevalence of initially very reduced UCVA (myopia) was similar in children with low and high SES (12.6% vs. 12.4%) (χ2; p = 0.153). After one year, the prevalence of very reduced UCVA increased to 14.1% in children with a low SES compared with 11.1% in children with a high SES (p = 0.001). Significant disparities related to SES were also found in PVA so that children with a low SES exhibited a greater reduction in PVA than children with a high SES (5.2% vs. 3.5%) (χ2; p = 0.004). (4) Conclusions: Children with a low SES showed an increase in reduced UCVA values over one year and a higher number of children with very reduced PVA compared with those with a high SES.

Prolonged exposure to rosuvastatin from pre-puberty to adulthood impairs sperm quality in mice and leads to paternally mediated developmental toxicity

Nowadays, changes in human lifestyle have increased dyslipidemia, reinforcing the necessity of using lipid-lowering drugs, such as statins, to control the lipid profile. Among the statins, rosuvastatin has shown greater efficacy in controlling dyslipidemia. Previous studies have shown adverse effects in adult men and pre-pubertal rodents after exposure to statins, such as reduced testosterone levels and delayed puberty. This study aimed to evaluate the reproductive parameters and fertility of male mice exposed to rosuvastatin from pre-puberty to sexual maturity by simulating human chronic exposure to rosuvastatin from pre-puberty to adulthood. This is the first study to evaluate male reproduction and developmental outcomes after prolonged rosuvastatin exposure since pre-puberty, mimicking the human exposure to relevant doses of the drug. Then, we hypothesize that prolonged exposure to rosuvastatin since pre-puberty may impair reproductive parameters in males and generate paternally mediated developmental toxicity. Male mice were divided into three experimental groups that received a 0.9 % saline solution, 1.5 or 5.5 mg/kg/day of rosuvastatin, by intragastric oral gavage, from postnatal day (PND) 23 to PND 80. Puberty onset was delayed and sperm quality was reduced in both rosuvastatin-treated groups. Furthermore, testicular interstitial tissue showed increased vascularization in a dose-dependent manner. After mating with non-treated females, the post-implantation loss rate increased in both rosuvastatin-exposed groups. There was an increase in the percentage of fetuses with opened eyelids in the offspring of males exposed to 1.5 mg/kg/day of the statin and a decrease in the craniocaudal distance of male offspring from males exposed to the higher dose. In summary, our hypothesis that rosuvastatin exposure would cause male reproductive toxicity and developmental impairment in the offspring of male mice was confirmed. This study raises concerns about the reproductive health of men who take this medication from infancy until adulthood in prolonged treatment.

Indications of younger age at menarche in Greek adolescents but with no relation to body mass index

PURPOSE

This study aimed to present recent trends in the pubertal timing of a Greek female sample.

METHODS

Data were collected retrospectively from medical records of healthy females aged 6-18 years who attended a tertiary Adolescent Friendly Health Center over a 5-year period (2016-2020) and included gestational age, birth anthropometrics, and age of thelarche and/or pubarche and/or menarche, along with corresponding anthropometric, hormonal, and biochemical measurements.

RESULTS

Data from 298 girls' medical records were included in the analysis. Median age at menarche, thelarche, and pubarche was 12, 9, and 9 years, respectively. The mean interval between pubertal onset and menarche was 1.99 years. The mean body mass index (BMI) at menarche and thelarche was 20.99 kg/m2 and 18.90 kg/m2, respectively. The mean weight at menarche was 49.6 kg, whereas the mean height difference between thelarche and menarche was 19.17 cm. Among participants, 6.3% had premature menarche, while 24.0% had premature thelarche. Birth weight was moderately correlated with BMI at thelarche/pubarche (rs=0.334, p = 0.005). Birth weight and BMI at thelarche/pubarche were not predictive of premature menarche or premature thelarche. Median (interquartile range, IQR) levels at menarche vs. thelarche were significantly higher for insulin-like growth factor-1 [358.00 (140.50) vs. 176.00 (55.00) ng/ml], follicle stimulation hormone [5.65 (3.14) vs. 3.10 (4.23) mIU/ml], testosterone [25.50 (31.00) vs. 13.00 (21.00) ng/dl], dehydroepiandrosterone sulfate [117.00 (112.50) vs. 46.40 (51.90) µg/dl], and insulin [17.40 (15.05) vs. 8.47 (4.97) µIU/ml].

CONCLUSION

The timing of pubertal stages in the Greek female sample studied followed the recent international downward trends. Younger age at menarche was not related to BMI.

Central Precocious Puberty in a Male Child With Down Syndrome: A Case Report

Gonadal dysfunction is a well-known endocrine manifestation of Down syndrome (DS) in men. Herein, we report a case of a seven-year-old boy with DS who developed precocious puberty, presenting with a six-month history of frequent erections, sudden growth spurts, and adult odors. Clinical examination revealed stage 2 puberty, with pubic hair development at stage 2 based on Tanner staging and bilateral testicular volumes of 6 mm. Laboratory tests indicated elevated luteinizing hormone (LH) and follicle-stimulating hormone levels and advanced bone age. A pituitary MRI revealed normal pituitary morphology without any detectable masses. The patient was initially prescribed monthly triptorelin acetate (Decapeptyl) intramuscular injections at a dose of 3.75 mg. Following six months, the treatment was switched to triptorelin pamoate (Diphereline) at a dose of 11.25 mg administered intramuscularly every three months. At age 10, following a three-year course of gonadotropin-releasing hormone (GnRH) agonist therapy, the patient demonstrated a notable decrease in testicular size and a reduction in LH levels, with no reported side effects. Conclusively, our findings imply that idiopathic central precocious puberty in boys with DS can be effectively managed with triptorelin pamoate injections, and early intervention may help alleviate the psychosocial impact of this condition.

The role of MicroRNAs as fine-tuners in the onset of puberty: a comprehensive review

MicroRNA (miRNA) are small, noncoding RNA molecules that play pivotal roles in gene expression, various biological processes, and development of disease. MiRNAs exhibit distinct expression patterns depending on time points and tissues, indicating their relevance to the development, differentiation, and somatic growth of organisms. MiRNAs are also involved in puberty onset and fertility. Although puberty is a universal stage in the life cycles of most organisms, the precise mechanisms initiating this process remain elusive. Genetic, hormonal, nutritional, environmental, and epigenetic factors are presumed contributors. The intricate regulation of puberty during growth also suggests that miRNAs are involved. This study aims to provide insight into the understanding of miRNAs roles in the initiation of puberty by reviewing the existing research.

Precocious puberty, pandemic and beyond

WHO declared SARS-COVID19 a pandemic in March 2020. Most governments declared health emergency states and implemented various measures. Since then, changes in the reasons for medical consultations were observed in healthcare institutions. Pediatric endocrinologists perceived an increase in the number of consultations related to early or accelerated CPP during the months following the lockdown that different governments had established. Several papers reported the increment in incidence in Central Precocious Puberty, especially in girls. Reports from different parts of the world highlighted a two to threefold rise in the number of cases of precocious puberty treated in Pediatric Endocrinology Centers. This trend of CPP incidence strongly suggests that changes in habits and the environment in which boys and girls were immersed during the lockdown, have played a significant role in triggering the early onset of the gonadotrophic axis.

The role of body composition and appetite-regulating hormones in idiopathic central precocious puberty and their changes during GnRH analog therapy

PURPOSE

It was aimed to compare circulating levels of ghrelin, leptin, peptide YY (PYY), and neuropeptide (NPY) between girls with idiopathic central precocious puberty (ICPP) and prepubertal girls, as well as to evaluate alterations in these hormone levels and body composition during leuprolide acetate treatment in girls with ICPP.

METHODS

This prospective study was conducted on girls with isolated premature thelarche (IPT), girls with ICPP, and age-matched prepubertal controls. Anthropometric measurements, body composition analysis and appetite-regulating hormone level measurements were performed in each group and also at the 6th and 12th months of the leuprolide acetate treatment for the girls with ICPP.

RESULTS

Seventy-three girls participated in the study (24 girls with ICPP, 28 with IPT, and 21 prepubertal controls). No significant differences were observed in ghrelin, leptin, PYY, and NPY levels among the three groups. Leuprolide acetate treatment resulted in increased leptin, decreased PYY and NPY levels, and no significant changes in ghrelin. Despite no significant change in body mass index standard deviation score (BMI SDS), body fat percentage increased during treatment.

CONCLUSION

While appetite-regulating hormones do not seem to directly contribute to precocious puberty pathogenesis, puberty blockade was shown to lead to altered levels of these hormones along with changes in body composition.

The functional study of a novel MKRN3 missense mutation associated with familial central precocious puberty

Central precocious puberty (CPP) refers to a syndrome of early puberty initiation with a characteristic increase in the release of gonadotropin-releasing hormone (GnRH); therefore, it is also called GnRH-related precocious puberty. About a quarter of idiopathic central precocious puberty (ICPP) may be familial. Studies suggest that mutations of makorin ring finger protein 3 (MKRN3) can cause familial central precocious puberty (FCPP). In this report, we describe a Chinese female patient carrying a novel MKRN3 variant (c.980G>A/p.Arg327His) and presenting the CPP phenotype. This novel variant attenuated its own ubiquitination, degradation, and inhibition on the transcriptional and translational activity of GNRH1, which was verified through functional tests. We can consider this variant as a loss-of-function mutation, which subsides the inhibition of GnRH1-related signaling and gives rise to GnRH-related precocious puberty.

Childhood physical activity and pubertal timing: findings from the LEGACY girls study

BACKGROUND

There is limited research on whether physical activity (PA) in early childhood is associated with the timing of pubertal events in girls.

METHODS

We used data collected over 2011-16 from the LEGACY Girls Study (n = 984; primarily aged 6-13 years at study enrolment), a multicentre North American cohort enriched for girls with a breast cancer family history (BCFH), to evaluate if PA is associated with age at thelarche, pubarche and menarche. Maternal-reported questionnaire data measured puberty outcomes, PA in early childhood (ages 3-5 years) and total metabolic equivalents of organized PA in middle childhood (ages 7-9 years). We used interval-censored Weibull parametric survival regression models with age as the time scale and adjusted for sociodemographic factors, and we tested for effect modification by BCFH. We used inverse odds weighting to test for mediation by body mass index-for-age z-score (BMIZ) measured at study enrolment.

RESULTS

Being highly active vs inactive in early childhood was associated with later thelarche in girls with a BCFH [adjusted hazard ratio (aHR) = 0.39, 95% CI = 0.26-0.59), but not in girls without a BCFH. In all girls, irrespective of BCFH, being in the highest vs lowest quartile of organized PA in middle childhood was associated with later menarche (aHR = 0.70, 95% CI = 0.50-0.97). These associations remained after accounting for potential mediation by BMIZ.

CONCLUSION

This study provides new data that PA in early childhood may be associated with later thelarche in girls with a BCFH, also further supporting an overall association between PA in middle childhood and later menarche.

Effect of nourishing and purging fire Chinese herbal mixture on delaying light-induced premature puberty in rats

OBJECTIVE

To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture (NYPF) in delaying light-induced premature puberty in rats.

METHODS

Twenty-one days old female Sprague-Dawley rats were randomly assigned to normal group (N), long light exposure group (L), NYPF and normal saline group (NS). Rats in the L, NYPF and NS groups were exposed to 16 h: 350 lux light/8 h: dark, while rats in the N group were exposed to 12 h: 50 lux light/12 h: dark. NYPF and normal saline was administered to the rats in the NYPF group or NS group, respectively, from day 21. Five rats in every group were sacrificed at 9 p.m. on day 28 (P28), on the day when rat's vulva opened in the L group (L-VO), on the day when the first estrous interphase occurred in rats of L group (L-E1), and on the day when the second estrous interphase occurred in rats of L group (L-E2), respectively.

RESULITS

On day 34, all rats in the L group, 80% of rats in the NS group, 40% of rats in the N group, and 20% of rats in the NYPF group showed complete opening of the vulva. At P28, mRNA level of hypothalamic kisspeptin (Kiss-1) in the L group was significantly higher than that in the N group (P < 0.05). The rats in the L and NS groups had significantly lower hypothalamic arginine-phenylalanine-amide (RFamide)-related peptide 3 (RFRP-3) mRNA levels than those in the N group (P < 0.05), whereas RFRP-3 mRNA level was significantly higher in the NYPF group than that in the L group (P < 0.05). At L-VO, the ovarian index of the L and NS groups was significantly higher than that of the N group (P < 0.05) and estradiol (E2) level of the NYPF group was significantly lower than that of the N and NS groups (P < 0.05); hypothalamic Kiss-1 mRNA level in the L and NS groups was significantly higher than that in the N and NYPF groups (P < 0.05), whereas hypothalamic RFRP-3 mRNA level in the L, NYPF, and NS groups was significantly lower than that in the N group (P < 0.05). At L-E1, E2 level of the L and NS groups was significantly higher than that of the N group (P < 0.01), whereas it was significantly lower in the NYPF group than that of the N, L, and NS groups (P < 0.01), and serum luteinizing hormone level of the L and NS groups was significantly higher than that of the N group (P < 0.05); levels of serum melatonin and ovarian melatonin receptor 1 (MT-1) mRNA in the L, NYPF, and NS groups were significantly lower than those in the N group (P < 0.05). At L-E2, the uterine organ index of the NYPF group was significantly lower than that of the L group (P < 0.05); and ovarian MT-1 mRNA level of the L and NS groups was significantly lower than that in the N group (P < 0.05).

CONCLUSIONS

NYPF can delay puberty onset in rats exposed to strong light for a prolonged duration, and regulation of the gene expression of Kiss-1 and RFRP-3 in the hypothalamus has been suggested as one of the mechanisms.

Time trends towards earlier puberty in boys and girls with type 1 diabetes: Insights from the German Diabetes Prospective Follow-up (DPV) registry, 2000 to 2021

AIM

To examine the time trends and factors associated with the onset of puberty in children with type 1 diabetes (T1D) using data from the German Diabetes Prospective Follow-up (Diabetes-Patienten-Verlaufsdokumentation [DPV]) registry.

METHODS

A total of 13 127 children with T1D, aged 6 to 18 years, were included in the analysis. Regression analysis was performed to investigate the relationship between diabetes duration, body mass index (BMI) standard deviation score (SDS), glycated haemoglobin (HbA1c) level, migration background, and the onset of puberty, stratified by sex.

RESULTS

Our findings revealed a significant trend towards earlier puberty in both girls and boys with T1D over the observed period (2000 to 2021). Puberty onset in girls (thelarche Tanner stage B2) decreased from 11.48 (11.35-11.65) years in 2000 to 10.93 (10.79-11.08) years in 2021 and gonadarche (Tanner stage G2/testicular volume >3 mL) decreased from 12.62 (12.42-12.82) years in 2000 to 11.98 (11.79-12.16) years in 2021 in boys (both P < 0.001). Longer diabetes duration, higher BMI SDS, and lower HbA1c level were associated with earlier puberty in both sexes (P < 0.001).

CONCLUSIONS

Our study highlights earlier puberty in children with T1D, influenced by BMI SDS, HbA1c level, and migration background. This has important implications for diabetes management and supporting healthy development. Further research is needed to understand the underlying mechanisms and develop potential interventions for this vulnerable population.

A dynamical model of growth and maturation in Drosophila

The decision to stop growing and mature into an adult is a critical point in development that determines adult body size, impacting multiple aspects of an adult's biology. In many animals, growth cessation is a consequence of hormone release that appears to be tied to the attainment of a particular body size or condition. Nevertheless, the size-sensing mechanism animals use to initiate hormone synthesis is poorly understood. Here, we develop a simple mathematical model of growth cessation in Drosophila melanogaster, which is ostensibly triggered by the attainment of a critical weight (CW) early in the last instar. Attainment of CW is correlated with the synthesis of the steroid hormone ecdysone, which causes a larva to stop growing, pupate, and metamorphose into the adult form. Our model suggests that, contrary to expectation, the size-sensing mechanism that initiates metamorphosis occurs before the larva reaches CW; that is, the critical-weight phenomenon is a downstream consequence of an earlier size-dependent developmental decision, not a decision point itself. Further, this size-sensing mechanism does not require a direct assessment of body size but emerges from the interactions between body size, ecdysone, and nutritional signaling. Because many aspects of our model are evolutionarily conserved among all animals, the model may provide a general framework for understanding how animals commit to maturing from their juvenile to adult form.

Precocious Puberty: Types, Pathogenesis and Updated Management

Precocious puberty (PP) means the appearance of secondary sexual characters before the age of eight years in girls and nine years in boys. Puberty is indicated in girls by the enlargement of the breasts (thelarche) in girls and in boys by the enlargement of the testes in either volume or length (testicular volume = 4 mL, testicular length = 25 mm, or both). Two types of PP are recognized - namely central PP (CPP) and peripheral PP (PPP). This paper aims to describe the clinical findings and laboratory workup of PP and to illustrate the new trends in the management of precocious sexual maturation. Gonadotropin-releasing hormone (GnRH)-independent type (PPP) refers to the development of early pubertal maturation not related to the central activation of the hypothalamic-pituitary-gonadal (HPG) axis. It is classified into genetic or acquired disorders. The most common forms of congenital or genetic causes involve McCune-Albright syndrome (MAS), familial male-limited PP, and congenital adrenal hyperplasia. The acquired causes include exogenous exposure to androgens, functioning tumors or cysts, and the pseudo-PP of profound primary hypothyroidism. On the other hand, CPP is the most common and it is a gonadotropin-dependent form. It is due to premature maturation of the HPG axis. CPP may occur as genetic alterations, such as MKRN3, DLK1, or KISS1;as a part of mutations in the epigenetic factors that regulate the HPG axis, such as Lin28b and let-7; or as a part of syndromes, central lesions such as hypothalamic hamartoma, and others. A full, detailed history and physical examination should be taken. Furthermore, several investigations should be conducted for both types of PP, including the estimation of serum gonadotropins such as luteinizing and follicle-stimulating hormones and sex steroids, in addition to a radiographic workup and thyroid function tests. Treatment depends on the type of PP: Long-acting GnRHa, either intramuscularly or implanted, is the norm of care for CPP management, while in PPP, especially in congenital adrenal hyperplasia, the goal of management is to suppress adrenal androgen secretion by glucocorticoids. In addition, anastrozole and letrozole - third-generation aromatase inhibitors - are more potent for MAS.

Is blue light exposure a cause of precocious puberty in male rats?

Purpose

Our study aimed to examine the effects of blue light exposure on prepubertal male rats' puberty and testis tissue.

Methods

Eighteen 21-day-old male Sprague Dawley rats were divided into three groups consisting of six rats in each group: Control Group (CG), Blue Light-6 hours (BL-6), and Blue Light-12 hours (BL-12). CG rats were maintained with 12/12-hour light-dark cycles. The rats of BL-6 and BL-12 were exposed to blue light (450-470nm/irradiance level 0.03uW/cm2) for 6 hours and 12 hours, respectively. Rats were exposed to blue light until the first signs of puberty. The ELISA method was used to analyze the serum levels of FSH, LH, testosterone, DHEA-S, leptin, ghrelin, melatonin, glutathione, glutathione peroxidase, and malondialdehyde. Testes were dissected for histomorphological examination.

Results

The medians of the pubertal entry days of the CG, BL-6, and BL-12 were 38^th, 30^th, and 28^th days, respectively. (p:0.001) The FSH, LH, and testosterone concentrations of all groups were similar. The FSH concentration increased as the LH concentration increased (r: 0.82 p: 0.001). The serum LH concentration increased as serum testosterone, and DHEAS decreased, respectively (r: -0.561, p: 0.01) (r:-0.55 p:0.01). Testicular lengths and weights of the BL groups were smaller compared to CG (p: 0.03),(p: 0.04). GPx was higher for BL-6 and BL-12 than the CG (p:0.021, p:0.024). Testis tissue was compatible with the pubertal period in all groups. As the blue light exposure time increased, spermatogenesis was suppressed, and capillary dilatation and edema in the testis tissue increased.

Conclusion

Our study is the first to show the effects of blue light exposure on male rats' puberty process. And we showed that exposure to blue light and the duration of exposure lead to precocious puberty in male rats. The blue light exposure suppressed spermatogenesis, marked vasodilatation in the interstitial area of the testis, and disrupted the integrity of the basement membrane. These findings intensified with increasing exposure time.

Impacts of the COVID-19 pandemic on the diagnosis of idiopathic central precocious puberty in pediatric females in New York City

BACKGROUND

The COVID-19 pandemic had profound effect on physical and mental health. Stress was due physical inactivity, increased screen time, social isolation, fear of illness/death, as well as relative lack of resources including healthy food and finances. These stressors may be associated with an increase in idiopathic central precocious puberty (ICPP).

OBJECTIVES

To assess the incidence of ICPP in females during the COVID-19 pandemic and compare biochemical and radiological parameters of females diagnosed in the previous two years, looking at associations among BMI, screen time, isolation, and stress in relation to the development of early puberty.

METHODS

A retrospective chart review was performed of females diagnosed with ICPP. We divided subjects into a pandemic group and pre-pandemic group based on time of diagnosis. We compared anthropometric, serologic and radiologic data between the two groups. To assess psychosocial stress, we reviewed a COVID-19 impact survey which was administered to families at our endocrine clinic.

RESULTS

There were a total of 56 subjects in the study; 23 subjects in the pre-pandemic group and 33 in the pandemic group. The pandemic cohort had significantly higher estradiol and LH levels and larger ovarian volumes. Survey results showed parental report of stress was moderate in 38 % of subjects and severe in 25 % of parents. In children, reported stress was moderate in 46 % of subjects.

CONCLUSIONS

As puberty is influenced by exogenous factors including weight gain and psychosocial stress, we suspect that the environmental stress surrounding the pandemic influenced the increase in ICPP.

Accuracy of doppler assessment of the uterine arteries for the diagnosis of pubertal onset in girls: a scoping review

The uterine artery pulsatility index (PI) assessed by Doppler ultrasound reflects the impedance to the blood flow in the vessel distal to the sampling point. We aimed to assess the accuracy of the uterine artery PI for the diagnosis of puberty in girls. A PRISMA-ScR-compliant scoping review was performed in the MEDLINE and Embase databases with the search terms "puberty" and "Doppler ultrasonography". Studies that included girls aged 0-18 years who underwent pelvic Doppler ultrasound with calculation of uterine artery PI were eligible. Ten studies comprising 1385 girls aged 1.2-18 years were included. The selected studies included participants from Italy, Brazil, Iran, Belgium and Denmark, and were published between 1996 and 2021. Six studies selected girls who were referred for evaluation of pubertal disorders, while four studies included only healthy girls. Nine studies found a significant difference in Doppler signal pattern and PI according to pubertal stage, with PI cutoff points ranging from 2.5 to 4.6 for the diagnosis of puberty, with a sensitivity of 77%-94%, specificity of 85%-100%, and accuracy of 79%-98%. Doppler assessment of the uterine arteries with PI calculation is a useful noninvasive tool in the diagnosis of pubertal onset in girls.

Endocrine Disruptor Chemicals and Children's Health

We are all exposed to endocrine-disrupting chemicals (EDCs) starting from embryonic life. The fetus and child set up crucial developmental processes allowing adaptation to the environment throughout life: they are extremely sensitive to very low doses of hormones and EDCs because they are developing organisms. Considering the developmental origin of well-being and diseases, every adult organism expresses consequences of the environment in which it developed. The molecular mechanisms through which the main EDCs manifest their effects and their potential association with endocrine disorders, such as diabetes, obesity, thyroid disease and alteration of adrenal hormones, will be reviewed here. Despite 40 years having passed since the first study on EDCs, little is yet known about them; therefore, our purpose is to take stock of the situation to establish a starting point for further studies. Since there is plenty of evidence showing that exposure to EDCs may adversely impact the health of adults and children through altered endocrine function-suggesting their link to endocrinopathies-it is essential in this context to bear in mind what is already known about endocrine disruptors and to deepen our knowledge to establish rules of conduct aimed at limiting exposure to EDCs' negative effects. Considering that during the COVID-19 pandemic an increase in endocrine disruptor effects has been reported, it will also be useful to address this new phenomenon for better understanding its basis and limiting its consequences.

The Circadian Clock, Nutritional Signals and Reproduction: A Close Relationship

The circadian rhythm, which is necessary for reproduction, is controlled by clock genes. In the mouse uterus, the oscillation of the circadian clock gene has been observed. The transcription of the core clock gene period (Per) and cryptochrome (Cry) is activated by the heterodimer of the transcription factor circadian locomotor output cycles kaput (Clock) and brain and muscle Arnt-like protein-1 (Bmal1). By binding to E-box sequences in the promoters of Per1/2 and Cry1/2 genes, the CLOCK-BMAL1 heterodimer promotes the transcription of these genes. Per1/2 and Cry1/2 form a complex with the Clock/Bmal1 heterodimer and inactivate its transcriptional activities. Endometrial BMAL1 expression levels are lower in human recurrent-miscarriage sufferers. Additionally, it was shown that the presence of BMAL1-depleted decidual cells prevents trophoblast invasion, highlighting the importance of the endometrial clock throughout pregnancy. It is widely known that hormone synthesis is disturbed and sterility develops in Bmal1-deficient mice. Recently, we discovered that animals with uterus-specific Bmal1 loss also had poor placental development, and these mice also had intrauterine fetal death. Furthermore, it was shown that time-restricted feeding controlled the uterine clock's circadian rhythm. The uterine clock system may be a possibility for pregnancy complications, according to these results. We summarize the most recent research on the close connection between the circadian clock and reproduction in this review.

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.

Mechanism of leptin-NPY on the onset of puberty in male offspring rats after androgen intervention during pregnancy

OBJECTIVES

The time of onset of puberty has been increasingly earlier, but its mechanism is still unclear. This study aimed to reveal the mechanism of leptin and NPY in the onset of puberty in male offspring rats after androgen intervention during pregnancy.

METHODS

Eight-week-old specific pathogen-free (SPF) healthy male Sprague-Dawley (SD) rats and 16 female SD rats were selected and caged at 1:2. The pregnant rats were randomly divided into the olive oil control group (OOG) and testosterone intervention group (TG), with 8 rats in each group. Olive oil and testosterone were injected from the 15th day of pregnancy, for a total of 4 injections (15th, 17th, 19th, 21st day). After the onset of puberty, the male offspring rats were anesthetized with 2% pentobarbital sodium to collect blood by ventral aorta puncture and decapitated to peel off the hypothalamus and abdominal fat. Serum testosterone (T), free testosterone (FT), dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), sex hormone binding globulin (SHBG), and leptin were detected by ELISA, and then the free androgen index (FAI) was calculated. The mRNA levels of androgen receptor (AR), estrogen receptor α (ERα), NPY, leptinR, and NPY2R in the hypothalamus and abdominal fat were detected by RT-PCR. Protein expression levels of AR, ERα, NPY, leptinR, and NPY2R in the arcuate nucleus (ARC) of the hypothalamus were detected by immunohistochemistry.

RESULTS

The time of onset of puberty was significantly earlier in the TG than in the OOG (P< 0.05) and was positively correlated with body weight, body length, abdominal fat, and leptinR mRNA levels in adipose tissue in the OOG (P< 0.05), while it was positively correlated with serum DHT and DHEA concentrations and FAI and AR mRNA levels in the hypothalamus in the TG (P< 0.05). The NPY2R mRNA level and protein expression levels of ERα, NPY2R, and leptinR in the TG were significantly higher than those in the OOG, while the protein expression levels of AR and NPY in the TG were significantly lower than those in the OOG (P< 0.05).

CONCLUSIONS

Testosterone intervention during pregnancy led to an earlier onset of puberty in male offspring rats, which may render the male offspring rats more sensitive to androgens, leptin, and NPY at the onset of puberty.

Childhood obesity and central precocious puberty

Childhood obesity is a major public health problem worldwide, and the relationship between obesity and central precocious puberty has long been confirmed, however, the mechanisms underlying this association remain elusive. This review provides an overview of the recent progress regarding how childhood obesity impacts on hypothalamic-pituitary-gonadal axis and pubertal onset, focusing on adipokines (leptin and ghrelin), hormone (insulin), and lipid (ceramide), as well as critical signaling pathways (AMPK/SIRT, mTOR) that integrate the peripheral metabolism and central circuits. Notably, prevention of obesity and CPP is beneficial for the adult life of the children, thus we further summarize the potential strategies in treating and preventing childhood obesity and CPP. The updated understanding of metabolic stress and pediatric endocrine disease will arise the attention of society, and also contribute to preventing more serious comorbidities in the later period of life in children.

Has the Frequency of Precocious Puberty and Rapidly Progressive Early Puberty Increased in Girls During the COVID-19 Pandemic?

Objective

Early puberty is development of secondary sex characteristics earlier than the expected normal age range. We subjectively observed an increased frequency of early puberty during the Coronavirus disease-2019 (COVID-19) lockdown and aimed to show the clinical, demographic characteristics of the cases and the change in its incidence.

Methods

Female patients with central precocious puberty (CPP, n=28) and rapidly progressive early puberty (RPEP, n=61), presenting to our clinic before (January 2019-March 2020) and during the COVID-19 pandemic (April 2020-June 2021) were included.

Results

Among 28 CPP cases, six (21%) presented before the pandemic lockdown, whereas 22 (79%) were diagnosed during the COVID-19 pandemic lockdown. While RPEP was seen in 16 (26%) patients before the pandemic, 45 (74%) patients were diagnosed during the lockdown period. Presentation with menarche was seen in 15 RPEP patients; two (13%) were in the prepandemic period and 13 (87%) were in the lockdown period. Chronological age, bone age, bone age to chronological age ratio, height, weight, and body mass index standard deviation scores of patients with RPEP and CPP were similar between the prepandemic and pandemic period.

Conclusion

In this cohort, the frequency of CPP and RPP cases were significantly (p<0.001) increased during the COVID-19 pandemic, possibly due to environmental changes.

Association between dehydroepiandrosterone sulphate levels at 7 years old and bone mineral density at 10 years old: a prospective cohort study

We aimed to explore the effect of dehydroepiandrosterone sulphate (DHEAS) at age 7 on areal bone mineral density (aBMD) at age 10 and to distinguish the direct and indirect effects (explained by sexual maturity and by aBMD at age 7), for each sex, after adjustment for body mass index (BMI) z-score. In a subsample of 274 children (139 girls, 135 boys) from Generation XXI cohort, aBMD was assessed with dual-energy X-ray absorptiometry (DXA) scan at ages 7 and 10. The increase in aBMD at age 10 for each 10 µg/dL increase in DHEAS levels at age 7 was estimated using path analysis. Both the direct and the indirect effects were calculated. In girls, higher DHEAS levels at age 7 were associated with higher aBMD at age 10. No direct effect was observed. The indirect effect via higher aBMD at age 7 explained 61% of the total effect, and the indirect effect via higher Tanner stage explained 21%. After adjustment for BMI, the total effect remained statistically significant, explained in 33% by the indirect effect of DHEAS on Tanner stage and Tanner stage on aBMD. In boys, no effect of DHEAS on aBMD was observed.

CONCLUSION

An indirect effect of DHEAS at age 7 on aBMD at age 10 was found in girls, but not in boys, as higher DHEAS levels were associated with more advanced sexual maturation at age 10, and more advanced sexual maturation to higher aBMD. No direct effect of DHEAS on aBMD was observed.

WHAT IS KNOWN

• Conditions associated with elevated DHEAS, adrenarche's biomarker, are accompanied by advanced bone maturity. • Whether adrenal androgens influence bone mineralization in childhood remains puzzling, and longitudinal data is scarce.

WHAT IS NEW

• In girls, but not in boys, higher DHEAS at age 7 was associated with higher aBMD at age 10. • This was partially explained by the indirect effect of DHEAS at age 7 on sexual maturity at age 10, as DHEAS at age 7 was positively associated with sexual maturity at age 10, which was further associated with aBMD.

Growth variations with opposite clinical outcomes and the emerging role of IGF-1

Normal growth pattern variations [i.e., constitutional advancement and constitutional delay of growth and puberty (CAGP and CDGP)] are the mirror image of each other and are associated with early puberty (EP) and delayed puberty (DP), respectively. Differences between CAGP and CDGP relate not only to auxological characteristics (height, weight) but also to insulin-like growth factor-1 (IGF-1). IGF-1 levels in CAGP are above average whereas in CDGP they are below average, suggesting a role for IGF-1 in the induction of these growth patterns. Herein, we provide data suggesting that early activation of the growth hormone (GH)/IGF-1 axis induces the growth pattern of CAGP. Moreover, we suggest that IGF-1 is a decisive factor for the release of the gonadotropin-releasing hormone (GnRH) inhibition brake that occurs in prepuberty. It is therefore crucial for puberty onset.

Genistein affects gonadotrophin-releasing hormone secretion in GT1-7 cells via modulating kisspeptin receptor and key regulators

Epidemiological studies have shown that genistein, an isoflavonoid phytoestrogen from soybean, affects endocrine and reproductive systems and alters pubertal onset. Administration of genistein in mice could impact the electrophysiology of hypothalamic neurons associated with the secretion of gonadotropin-releasing hormone (GnRH), a key component of hypothalamic-pituitary-gonadal (HPG) axis that governs hormone release and reproductive maturation. However, whether genistein could directly influence GnRH secretion in GnRH-specific neurons requires further investigation. Here, mouse hypothalamic GT1-7 neurons were recruited as a GnRH-expressing model to directly evaluate the effect and mechanisms of genistein on GnRH release. Results from this study demonstrated that genistein treatment decreased cell viability, impacted cell cycle distribution, and induced apoptosis of GT1-7 cells. A high concentration of genistein (20 μM) significantly increased GnRH secretion by 122.4% compared to the control. Since GnRH release is regulated by components of the kisspeptin-neurokinin-dynorphin (KNDy) system and regulators including SIRT1, PKC_γ, and MKRN3, their transcription and translation were examined. Significant increases were observed for the mRNA and protein levels of the KNDy component kisspeptin receptor (Gpr54/Kissr). Compared to the control, genistein treatment upregulated the level of Sirt1 mRNA level, while it downregulated Prkcg and Mkrn3 expression. Therefore, this study provided direct evidence that genistein treatment could affect GnRH secretion by modulating kisspeptin receptors, SIRT1, PKC_γ and MKRN3 in GT1-7 cells.Abbreviations: GnRH: gonadotropin-releasing hormone; HPG: hypothalamic-pituitary-gonadal; KNDy: kisspeptin-neurokinin-dynorphin; LH: luteinizing hormone; FSH: follicle-stimulating hormone; ARC: arcuate nucleus; ER: estrogen receptor; SIRT1: silent information regulator 1; PKCγ: protein kinase c γ: MKRN3: makorin ring finger protein 3; LC: lethal concentration; PI: propidium iodide; ECL: chemiluminescence; BCA: bicinchoninic acid assay; PBS: phosphate-buffered saline; CT: fluorescence reached threshold; PVDF: polyvinylidene difluoride.

Genetic, epigenetic and enviromental influencing factors on the regulation of precocious and delayed puberty

The pubertal development onset is controlled by a network of genes that regulate the gonadotropin releasing hormone (GnRH) pulsatile release and the subsequent increase of the circulating levels of pituitary gonadotropins that activate the gonadal function. Although the transition from pre-pubertal condition to puberty occurs physiologically in a delimited age-range, the inception of pubertal development can be anticipated or delayed due to genetic and epigenetic changes or environmental conditions. Most of the genetic and epigenetic alterations concern genes which encode for kisspeptin, GnRH, LH, FSH and their receptor, which represent crucial factors of the hypothalamic-pituitary-gonadal (HPG) axis. Recent data indicate a central role of the epigenome in the regulation of genes in the hypothalamus and pituitary that could mediate the flexibility of pubertal timing. Identification of epigenetically regulated genes, such as Makorin ring finger 3 (MKRN3) and Delta-like 1 homologue (DLK1), respectively responsible for the repression and the activation of pubertal development, provides additional evidence of how epigenetic variations affect pubertal timing. This review aims to investigate genetic, epigenetic, and environmental factors responsible for the regulation of precocious and delayed puberty.

Assessing puberty in female cheetahs (Acinonyx jubatus) via faecal hormone metabolites and body weight

With fewer than 7500 cheetahs remaining in the wild, ex situ cheetah populations serve as an insurance policy against extinction and a resource to study species' biology. This study aimed to identify the age of pubertal onset in ex situ female cheetahs using non-invasive faecal steroid hormone monitoring and body weights. Faecal samples from nine female cheetahs were collected two to three times weekly from 2 to 36months of age and body weights were recorded every 3months. Faecal oestrogen metabolites (FOM) and faecal glucocorticoid metabolites (FGM) were analysed using enzyme immunoassays and samples were categorised into 6-month intervals to compare endocrine characteristics. Faecal hormone and body weight data were analysed using generalised linear mixed models. Age was a significant predictor of mean and baseline FOM concentrations, number of FOM peaks, mean and maximum FOM peak concentrations and the number of cycles. Female cheetahs aged 24-30months exhibited a marked rise in mean FOM concentration and the number of FOM peaks and cycles increased with age until 24-30months. Females attained adult body weight by 21months of age. Mean and baseline FGM concentrations were highest at the 0-6 and 12-18months of age groups and did not follow the same FOM patterns. Based on body weight data, the FOM concentrations and peak patterning, females were considered pubertal from 24 to 30months of age. Characterisation of cheetah puberty has direct and significant implications for the improvement of management and reproductive success of cheetahs under human care. This information is particularly informative for identifying important windows of development, littermate dispersal and breeding introductions.

Genetic and Epigenetic Control of Puberty

Puberty is a complex transitional phase in which reproductive capacity is achieved. There is a very wide variation in the age range of the onset of puberty, which follows a familial, ethnic, and sex pattern. The hypothalamic-pituitary-gonadal axis and several genetic, environmental, and nutritional factors play an important role in the onset of and throughout puberty. Recently, there has been significant progress in identifying factors that affect normal pubertal timing. Different studies have identified single nucleotide polymorphisms (SNPs) that affect pubertal timing in both sexes and across ethnic groups. Single genes are implicated in both precocious and delayed puberty, and epigenetic mechanisms have been suggested to affect the development and function of the GnRH neuronal network and responsiveness of end organs. All these factors can influence normal puberty timing, precocious puberty, and delayed puberty. The objective of this review is to describe recent findings related to the genetic and epigenetic control of puberty and highlight the need to deepen the knowledge of the regulatory mechanisms of this process in the normal and abnormal context.

Diagnosis and management of precocious sexual maturation: an updated review

The classic definition of precocious sexual maturation is the development of secondary sexual characteristics before 8 years of age in girls and before 9 years of age in boys. It is classified as central precocious puberty when premature maturation of the hypothalamic-pituitary-gonadal axis occurs, and as peripheral precocious puberty when there is excessive secretion of sex hormones, independent of gonadotropin secretion. Precocious sexual maturation is more common in girls, generally central precocious puberty of idiopathic origin. In boys, it tends to be linked to central nervous system abnormalities. Clinical evaluation should include a detailed history and physical examination, including anthropometric measurements, calculation of growth velocity, and evaluation of secondary sexual characteristics. The main sign to suspect the onset of puberty is breast tissue development (thelarche) in girls and testicular enlargement (≥4 mL) in boys. Hormonal assessment and imaging are required for diagnosis and identification of the etiology. Genetic testing should be considered if there is a family history of precocious puberty or other clinical features suggestive of a genetic syndrome. Long-acting gonadotropin-releasing hormone analogs are the standard of care for central precocious puberty management, while peripheral precocious puberty management depends on the etiology.Conclusion: The aim of this review is to address the epidemiology, etiology, clinical assessment, and management of precocious sexual maturation. What is Known: • The main sign to suspect the onset of puberty is breast tissue development (thelarche) in girls and testicular enlargement (≥4 mL) in boys. The classic definition of precocious sexual maturation is the development of secondary sexual characteristics before 8 years of age in girls and before 9 years of age in boys. • Long-acting gonadotropin-releasing hormone agonist (GnRHa) is the standard of care for CPP management, and adequate hormone suppression results in the stabilization of pubertal progression, a decline in growth velocity, and a decrease in bone age advancement. What is New: • Most cases of precocious sexual maturation are gonadotropin-dependent and currently assumed to be idiopathic, but mutations in genes involved in pubertal development have been identified, such as MKRN3 and DLK1. • A different preparation of long-acting GnRHa is now available: 6-month subcutaneous injection.

Disorders of Puberty in Girls

Puberty is the process through which reproductive competence is achieved and comprises gonadarche and adrenarche. Breast development is the initial physical finding of pubertal onset in girls and typically occurs between 8 and 13 years. Menarche normally occurs 2 to 3 years after the onset of breast development. Pubertal onset is controlled by the gonadotropin-releasing hormone pulse generator in the hypothalamus; however, environmental factors such as alterations in energy balance and exposure to endocrine-disrupting chemicals can alter the timing of pubertal onset. Improvement in nutritional and socioeconomic conditions over the past two centuries has been associated with a secular trend in earlier pubertal onset. Precocious puberty is defined as onset of breast development prior to 8 years and can be central or peripheral. Delayed puberty can be hypogonadotropic or hypergonadotropic and is defined as lack of breast development by 13 years or lack of menarche by 16 years. Both precocious and delayed puberty may have negative effects on self-esteem, potentially leading to psychosocial stress. Patients who present with pubertal differences require a comprehensive assessment to determine the underlying etiology and to devise an effective treatment plan.

The link between obesity and puberty: what is new?

PURPOSE OF REVIEW

The objective of this review is to assess the most recent literature on pubertal trends in boys and girls as well as evaluate genetic, epigenetic, and environmental factors implicated in the timing of pubertal progression.

RECENT FINDINGS

Recent studies confirm the previously described link between increased adiposity and earlier onset of puberty in girls, and more recent studies shed light onto the previously unclear situation in boys as a preponderance of recent longitudinal studies suggests that increased adiposity is linked with earlier pubertal timing also in boys. Discoveries of novel pathways highlights the complexity of pubertal development and suggest mechanistic links between nutrition, obesity, leptin, insulin resistance, and puberty. Furthermore, genetic and epigenetic variants can be linked to early puberty. Other factors, such as prenatal and postnatal environment, gut microbiota, and endocrine-disrupting chemicals have also been linked to both obesity and earlier puberty.

SUMMARY

Understanding how the interactions of these factors contribute the relationship between obesity and early pubertal onset is crucial as early puberty has been linked with long-term consequences, such as short stature, earlier type 2 diabetes, cardiovascular disease, and poor psychological and behavioral outcomes.

Biological clock and heredity in pubertal timing: what is new?

Puberty represents a milestone during a person's life and is characterized by several physical and psychological changes which end with the achievement of sexual maturation and of fertility. Puberty onset depends on a series of sophisticated, not completely understood, mechanisms certainly involving Gonadotropin-Releasing Hormone (GnRH) and its effects on pituitary gonadotropins. As recent evidence has demonstrated that pubertal timing deeply affects future adult health life, much efforts have been performed in order to clarify the exact actors involved in the onset and progression of puberty. Genetic factors are undoubtedly essential players in the regulation of pubertal development, accounting for approximately 50-80% of its variability. Mutations in genes such as KISS1, MKRN3 and DLK1 have been associated with central precocious puberty. Interestingly, a possible involvement of epigenetic mechanisms has been proposed as additional element able to affect pubertal phase. Environmental factors have recently attracted much attention. Indeed, an overall decrease in the age of puberty has been observed in the last decades. As genetic factors require long time to exert their effect, other players, such as environmental ones, may be involved. Special focus has been posed on nutritional status, endocrine-disrupting chemicals with non-conclusive results. Pubertal timing deeply affects future life, suggesting the need to clarify mechanisms driving pubertal onset and progression, in order to identify tailored therapeutic strategies and targets.

The KiNG of reproduction: Kisspeptin/ nNOS interactions shaping hypothalamic GnRH release

Gonadotropin-releasing hormone (GnRH) is the master regulator of the hypothalamic-pituitary-gonadal (HPG) axis, and therefore of fertility and reproduction. The release pattern of GnRH by the hypothalamus includes both pulses and surges. However, despite a considerable body of evidence in support of a determinant role for kisspeptin, the mechanisms regulating a GnRH pulse and surge remain a topic of debate. In this review we challenge the view of kisspeptin as an absolute "monarch", and instead present the idea of a Kisspeptin-nNOS-GnRH or "KiNG" network that is responsible for generating the "GnRH pulse" and "GnRH surge". In particular, the neuromodulator nitric oxide (NO) has opposite effects to kisspeptin on GnRH secretion in many respects, acting as the Yin to kisspeptin's Yang and creating a dynamic system in which kisspeptin provides the "ON" signal, promoting GnRH release, while NO mediates the "OFF" signal, acting as a tonic brake on GnRH secretion. This interplay between an activator and an inhibitor, which is in turn fine-tuned by the gonadal steroid environment, thus leads to the generation of GnRH pulses and surges and is crucial for the proper development and function of the reproductive axis.

The role of the hypothalamus and pituitary epigenomes in central activation of the reproductive axis at puberty

Puberty is programmed through a multifactorial gene network which works to activate the pulsatile secretion of the gonadotropin releasing hormone (GnRH), and subsequently elevate circulating levels of the pituitary gonadotropins that stimulate gonadal activity. Although this developmental transition normally occurs at a limited age-range in individuals of the same genetic background and environment, pubertal onset can occur prematurely or be delayed following changes in ambient conditions, or due to genetic variations or mutations, many of which have remained elusive due to their location in distal regulatory elements. Growing evidence is pointing to a pivotal role for the epigenome in regulating key genes in the reproductive hypothalamus and pituitary at this time, which might mediate some of the plasticity of pubertal timing. This review will address epigenetic mechanisms which have been demonstrated in the KNDy neurons that increase the output of pulsatile GnRH, and those involved in activation of the GnRH gene and its receptor, and describes how GnRH utilizes epigenetic mechanisms to stimulate transcription of the pituitary gonadotropin genes in the context of the chromatin landscape.

Clinical expression of endocrine disruptors in children

PURPOSE OF REVIEW

Health status is the result of complex interaction between individual factors, general environmental factors and specific factors as nutrition or the presence of chemicals. Aim of this review is to point out the more recent knowledge covering the role of the endocrine disrupting chemical (EDC) on pediatric population wellbeing.

RECENT FINDINGS

Prenatal, postnatal life and puberty are the three main temporal windows of susceptibility when EDCs may act. The mechanism is independent from dose or duration of exposition, sex, age or combination of chemicals and may also be transgenerational, affecting both growth and pubertal timing. A window of susceptibility for breast cancer has been detected. Thyroid gland is influenced by environmental chemicals, both in utero and during childhood. Alteration in Thyrotropin stimulating hormone (TSH) levels and neurodevelopmental impairment have been demonstrate. It has been detected a pro-obesogenic action of specific chemicals, impairing also glucose homeostasis during childhood.

SUMMARY

With a multidisciplinary approach and the use of big data platforms, an attempt has to be made to verify biological variations related to a disease, and how much the risk is influenced by the presence of the endocrine disruptors. This may help the future generation to better interpret uncommunicable diseases.