Synchronization of augmented luteinizing hormone secretion with sleep during puberty

Urinary gonadotropin assay on 24-h collections as a tool to detect early central puberty onset in girls: determination of predictive thresholds

STUDY QUESTION

Is the 24-h urinary gonadotropin assay an effective diagnostic tool in central precocious puberty (CPP) in girls?

SUMMARY ANSWER

This study is the first to provide 24-h urinary gonadotropin assay data, using an electrochemiluminescent immunoassay (CMIA), and to report its usefulness as a tool for the diagnosis of CPP.

WHAT IS KNOWN ALREADY

Data about the GnRH test in the diagnosis of CPP are variable and there is no consensus regarding its interpretation. The measurement of FSH and LH in urines was previously reported to be an alternative biological tool.

STUDY DESIGN, SIZE, DURATION

This is a retrospective two-cohort study, involving a setting and a validation cohort. A total of 516 girls, included between October 2012 and July 2015, and 632 urinary collections were analyzed in the setting cohort. In the validation cohort, 39 girls were included between January 2021 and May 2023, and 49 urinary collections were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study included girls who consulted for an investigation of disturbed growth rate or a clinical suspicion of puberty onset in different medical centres across France (setting cohort). Girls with a suspicion of precocious puberty onset were addressed at the expert centre of paediatric endocrinology of the Groupement Hospitalier Lyon Est (validation cohort). Pelvic ultrasonography was performed and enabled their classification according to clinical and morphologic changes criteria (prepubertal or pubertal groups). The parents collected 24-h urine samples (u24) according to standardized instructions. FSH and LH (urinary or plasmatic) were measured using a current and automated CMIA.

MAIN RESULTS AND THE ROLE OF CHANCE

The area under the ROC curves for CPP prediction was 0.709 for u24FSH (P < 0.001), 0.767 for u24LH (P < 0.001), and 0.753 for the u24LH/u24FSH ratio (P < 0.001). We retained all possible combinations of the four thresholds in the validation cohort (u24FSH = 1.1 or 2.0 IU/24 h; u24LH = 0.035 or 0.08 IU/24 h). The combination of u24FSH > 1.1 IU/24 h and u24LH > 0.08 IU/24 h had a positive PV of 85.7% and a negative PV of 94.3%, a sensitivity of 85.7% and a specificity of 94.3%, for classifying prepubertal and pubertal girls in this cohort.

LIMITATIONS, REASONS FOR CAUTION

This is a retrospective study, in which a margin of error remains due to the inherent uncertainty regarding the clinical assessment of pubertal onset. It must be considered that the thresholds can only apply to the used reagents; measurements without extractions using other reagents are likely to show important heterogeneity.

WIDER IMPLICATIONS OF THE FINDINGS

The assay performed herein is a simple, non-invasive, and analytically robust technique meeting the criteria for an alternative to the GnRH test which could be used to supplement its lack of sensitivity.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was used. All authors declared no conflict of interest.

TRIAL REGISTRATION NUMBER

In-house #23-5214 registered study.

Sex and Sleep Disruption as Contributing Factors in Alzheimer's Disease

Alzheimer's disease (AD) affects more women than men, with women throughout the menopausal transition potentially being the most under researched and at-risk group. Sleep disruptions, which are an established risk factor for AD, increase in prevalence with normal aging and are exacerbated in women during menopause. Sex differences showing more disrupted sleep patterns and increased AD pathology in women and female animal models have been established in literature, with much emphasis placed on loss of circulating gonadal hormones with age. Interestingly, increases in gonadotropins such as follicle stimulating hormone are emerging to be a major contributor to AD pathogenesis and may also play a role in sleep disruption, perhaps in combination with other lesser studied hormones. Several sleep influencing regions of the brain appear to be affected early in AD progression and some may exhibit sexual dimorphisms that may contribute to increased sleep disruptions in women with age. Additionally, some of the most common sleep disorders, as well as multiple health conditions that impair sleep quality, are more prevalent and more severe in women. These conditions are often comorbid with AD and have bi-directional relationships that contribute synergistically to cognitive decline and neuropathology. The association during aging of increased sleep disruption and sleep disorders, dramatic hormonal changes during and after menopause, and increased AD pathology may be interacting and contributing factors that lead to the increased number of women living with AD.

FTO-mediated m6A demethylation regulates GnRH expression in the hypothalamus via the PLCβ3/Ca2+/CAMK signalling pathway

N6-methyladenosine (m6A) plays a crucial role in the development and functional homeostasis of the central nervous system. The fat mass and obesity-associated (FTO) gene, which is highly expressed in the hypothalamus, is closely related to female pubertal development. In this study, we found that m6A methylation decreased in the hypothalamus gradually with puberty and decreased in female rats with precocious puberty. FTO expression was increased at the same time. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) showed that the m6A methylation of PLCβ3, a key enzyme of the Ca2+ signalling pathway, was decreased significantly in the hypothalamus in precocious rats. Upregulating FTO increased PLCβ3 expression and activated the Ca2+ signalling pathway, which promoted GnRH expression. Dual-luciferase reporter and MeRIP-qPCR assays confirmed that FTO regulated m6A demethylation of PLCβ3 and promoted PLCβ3 expression. Upon overexpressing FTO in the hypothalamic arcuate nucleus (ARC) in female rats, we observed advanced puberty onset. Meanwhile, PLCβ3 and GnRH expression in the hypothalamus increased significantly, and the Ca2+ signalling pathway was activated. Our study demonstrates that FTO enhances GnRH expression, which promotes puberty onset, by regulating m6A demethylation of PLCβ3 and activating the Ca2+ signalling pathway.

The Menstrual Cycle and Sleep

Aspects of sleep change across the menstrual cycle in some women. Poorer sleep quality in the premenstrual phase and menstruation is common in women with premenstrual symptoms or painful menstrual cramps. Although objective sleep continuity remains unchanged across the regular, asymptomatic menstrual cycle, activity in the sleep electroencephalogram varies, with a prominent increase in sleep spindle activity in the postovulatory luteal phase, when progesterone is present, relative to the follicular phase. Menstrual cycle phase, reproductive stage, and menstrual-related disorders should be considered when assessing women's sleep complaints.

Mechanisms and predictors of menses resumption once normal weight is reached in anorexia nervosa

BACKGROUND

In cases of Anorexia Nervosa (AN), achieving weight gain recovery beyond the lower limits set by the World Health Organization and normalizing classical nutritional markers appears to be essential for most patients. However, this is not always adequate to restore menstrual cycles. This discrepancy can cause concern for both patients and healthcare providers, and can impact the medical management of these individuals. Thus, the purpose of this study was to assess the ability of anthropometric and hormonal factors to predict the resumption of menstrual cycles in individuals with anorexia nervosa upon reaching a normal body weight.

METHOD

Patients with AN who had achieved a normal Body Mass Index but had not yet resumed their menstrual cycles (referred to as ANRec) were evaluated on two occasions: first at visit 1 and then again 6 months later, provided their body weight remained stable over this period (visit 2). Among the 46 ANRec patients who reached visit 2, they were categorized into two groups: 20 with persistent amenorrhea (PA-ANRec) and 26 who had regained their menstrual cycles (RM-ANRec). Anthropometric measurements, several hormone levels, Luteinizing Hormone (LH) pulsatility over a 4-h period, and LH response to gonadotropin-releasing hormone injection (LH/GnRH) were then compared between the two groups at visit 1.

RESULTS

Patients in the RM-ANRec group exhibited higher levels of follicular stimulating hormone, estradiol, inhibin B, LH/GnRH, and lower levels of ghrelin compared to those in the PA-ANRec group. Analysis of Receiver Operating Characteristic curves indicated that having ≥ 2 LH pulses over a 4-h period, LH/GnRH levels ≥ 33 IU/l, and inhibin B levels > 63 pg/ml predicted the resumption of menstrual cycles with a high degree of specificity (87%, 100%, and 100%, respectively) and sensitivity (82%, 80%, and 79%, respectively).

CONCLUSIONS

These three hormonal tests, of which two are straightforward to perform, demonstrated a high predictive accuracy for the resumption of menstrual cycles. They could offer valuable support for the management of individuals with AN upon achieving normalized weight. Negative results from these tests could assist clinicians and patients in maintaining their efforts to attain individualized metabolic targets.

TRIAL REGISTRATION

IORG0004981.

Objective and subjective sleep health in adolescence: Associations with puberty and affect

Sleep health tends to worsen during adolescence, partially due to pubertal-related changes that, in combination with social and psychological factors, can lead to long-lasting impairments in sleep health and affective functioning. Discrepant findings between subjective and objective measures of sleep in relation to affect have been reported in studies of adults; however, few investigations have assessed both subjective and objective sleep quality in a single sample, and fewer have examined this in the context of pubertal development. We aimed to (1) characterise pubertal associations with subjective sleep satisfaction, objective sleep efficiency, and objective and subjective sleep duration in adolescents; (2) examine the longitudinal association between daily affect and sleep metrics; and (3) test whether pubertal stage moderated this association. Eighty-nine participants (64% female, ages 13-20) completed an ecological momentary assessment (EMA) and actigraphy protocol. Independent of age, advanced pubertal stage was associated with lower subjective sleep satisfaction but not with objective sleep indices. Subjective sleep satisfaction was associated with within-person trajectories of negative affect, but not with positive affect. Pubertal stage and sleep satisfaction did not interact to predict within-day negative or positive affect. These findings are consistent with previous reports showing that objective and subjective sleep health are associated differently with puberty, and that subjective sleep health is associated with daily affect. Pubertal stage may be a more important indicator of subjective sleep quality in adolescence than is chronological age, most likely due to hormonal changes and psychological adjustment to the physical changes associated with the pubertal transition.

Discrete-time Survival Analysis of Risk Factors for Early Menarche in Korean Schoolgirls

OBJECTIVES

The aim of this study was to evaluate the effect of body weight status and sleep duration on the discrete-time hazard of menarche in Korean schoolgirls using multiple-point prospective panel data.

METHODS

The study included 914 girls in the 2010 Korean Children and Youth Panel Study who were in the elementary first-grader panel from 2010 until 2016. We used a Gompertz regression model to estimate the effects of weight status based on age-specific and sex-specific body mass index (BMI) percentile and sleep duration on an early schoolchild's conditional probability of menarche during a given time interval using general health condition and annual household income as covariates.

RESULTS

Gompertz regression of time to menarche data collected from the Korean Children and Youth Panel Study 2010 suggested that being overweight or sleeping less than the recommended duration was related to an increased hazard of menarche compared to being average weight and sleeping 9 hours to 11 hours, by 1.63 times and 1.38 times, respectively, while other covariates were fixed. In contrast, being underweight was associated with a 66% lower discrete-time hazard of menarche.

CONCLUSIONS

Weight status based on BMI percentiles and sleep duration in the early school years affect the hazard of menarche.

Sex steroid priming in short stature children unresponsive to GH stimulation tests: Why, who, when and how

Despite decades of experience, the diagnosis of growth hormone deficiency (GHD) remains challenging, especially in peripubertal children. Failure to respond to GH stimulation tests (GHSTs) is needed to confirm GHD, but long-standing controversies regarding the number of tests needed and the interpretation of GH peaks are still a matter of debate worldwide. Diagnostic workup is even more problematic in short children with slow growth and delayed sexual development: they often exhibit low GH peaks under GHST, which often normalize as puberty progresses. Consequently, this transient suboptimal response to GHST may result in GH overtreatment, carrying both health and economic concerns. Considering the complex and bound link between GH axis and sex steroids, the use of sex steroid priming prior to GHST might be helpful in peripubertal setting. However, its use is still controversial. There is no consensus regarding patient selection, timing, dose, and preparation of sex steroids. In this review, we aim to overview the use of sex steroid priming in clinical practice, highlighting the need to develop appropriate guidelines in order to overcome diagnostic pitfalls in peripubertal age.

Timing of Puberty and Late Pubertal Height in Saudi Schoolboys: Riyadh Puberty Study II

OBJECTIVE

Puberty has a significant contribution to the final height. Therefore, it is crucial to understand the normal variations in the onset and tempo of puberty in a specific population. In this study, we aimed to provide normative data on the timing of puberty and late pubertal height (LPH) in Saudi schoolboys in Riyadh.

METHODS

This is a cross-sectional field study (2011-2013) including Saudi schoolboys (grades 1-12; aged 6 to 19 years). Schools were chosen to represent the population from urban and rural areas in the Riyadh region. Pubertal maturity staging for gonads was assessed by measuring testicular size using a Prader orchidometer and assessing the Tanner staging of pubic hair. The marginal mean age was calculated using regression analysis.

RESULTS

We recruited 1086 schoolboys. The estimated mean age of pubertal onset at G2 was 11.8 (95% CI 11.60-12.0) years, for gonadal development at G3 was 13.2 (95% CI 12.9-13.5), G4 = 15.0 (95% CI 14.7-15.2), and G5 = 16.1 (95% CI 15.9-16.3) years, and for pubic hair stage 2 (PH2) was 12.6 (95% CI 12.4-12.9) years. The estimated time from G2/PH2 to G5/PH5 was 4.3 and 3.9 years, respectively. At the onset of puberty, the mean height was 144.7 cm and it reached 167.8 cm at G5 with a pubertal height gain of 23.1 cm.

CONCLUSION

Our data present the norms of the timing of puberty and LPH in Saudi schoolboys. Saudi adolescent males are shorter than some European and American comparatives mainly due to shortness during childhood. However, they could have shorter LPH than Turkish, Greek, Thai, and Japanese due to a less pubertal height gain.

Sleep and Puberty

In the 1970's, Boyar and colleagues made the seminal observation that during the early stages of puberty, there is a sleep-specific augmentation of pulsatile luteinizing hormone (LH) secretion. Building on this tantalizing association between sleep and the re-awakening of the neuro-reproductive axis, a number of investigators have since mapped the dynamic relationship between sleep and reproductive hormones across the pubertal transition. In this review, we focus on the complex, reciprocal relationship between sleep and reproductive hormones during adolescence as well as the potential effects of melatonin and orexin on gonadotropin-releasing hormone (GnRH) activity in children with chronic insomnia and narcolepsy, respectively. Given the important interaction between the reproductive and somatotropic axes during puberty, we end with a discussion of sleep and growth hormone (GH) secretion in children.

A Longitudinal Study of Subjective Daytime Sleepiness Changes in Elementary School Children Following a Temporary School Closure Due to COVID-19

Excessive daytime sleepiness is increasingly being recognized as a major global health concern. However, there have been few studies related to sleepiness and its associated factors in elementary school children. In Japan, all schools were closed from February to May 2020 to prevent coronavirus disease 2019 (COVID-19) outbreaks. The aim of this study was to identify changes in the subjective sleepiness of pupils during the 1.5-year period and to elucidate factors associated with changes in sleepiness. Questionnaire surveys about pupils’ sleep habits and the Japanese version of the Pediatric Daytime Sleepiness Scale (PDSS-J) were conducted longitudinally at one elementary school in June 2019, January 2020, and June 2020. The average ∆PDSS score was 0.94 ± 5.51 (mean ± standard deviation) from June 2019 to January 2020 and −1.65 ± 5.71 (t[498] = 6.13, p < 0.01) from January 2020 to June 2020. Univariate and multivariate logistic regression analyses revealed that decreasing social jetlag was associated with decreasing PDSS scores (OR = 0.77, 95% CI: 0.62–0.96, p = 0.02) during the school closure. A less restrictive school schedule secondary to a COVID-19-related school closure decreased sleepiness in children and was associated with decreasing social jetlag.

Using Aptamers as a Novel Method for Determining GnRH/LH Pulsatility

Aptamers are a novel technology enabling the continuous measurement of analytes in blood and other body compartments, without the need for repeated sampling and the associated reagent costs of traditional antibody-based methodologies. Aptamers are short single-stranded synthetic RNA or DNA that recognise and bind to specific targets. The conformational changes that can occur upon aptamer–ligand binding are transformed into chemical, fluorescent, colour changes and other readouts. Aptamers have been developed to detect and measure a variety of targets in vitro and in vivo. Gonadotropin-releasing hormone (GnRH) is a pulsatile hypothalamic hormone that is essential for normal fertility but difficult to measure in the peripheral circulation. However, pulsatile GnRH release results in pulsatile luteinizing hormone (LH) release from the pituitary gland. As such, LH pulsatility is the clinical gold standard method to determine GnRH pulsatility in humans. Aptamers have recently been shown to successfully bind to and measure GnRH and LH, and this review will focus on this specific area. However, due to the adaptability of aptamers, and their suitability for incorporation into portable devices, aptamer-based technology is likely to be used more widely in the future.

Using Kisspeptin to Predict Pubertal Outcomes for Youth With Pubertal Delay

CONTEXT

The management of youth with delayed puberty is hampered by difficulty in predicting who will eventually progress through puberty and who will fail to attain adult reproductive endocrine function. The neuropeptide kisspeptin, which stimulates gonadotropin-releasing hormone (GnRH) release, can be used to probe the integrity of the reproductive endocrine axis.

OBJECTIVE

We sought to determine whether responses to kisspeptin can predict outcomes for individuals with pubertal delay.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a longitudinal cohort study in an academic medical center of 16 children (3 girls and 13 boys) with delayed or stalled puberty.

INTERVENTION AND OUTCOME MEASURES

Children who had undergone kisspeptin- and GnRH-stimulation tests were followed every 6 months for clinical evidence of progression through puberty. Inhibin B was measured in boys. A subset of participants underwent exome sequencing.

RESULTS

All participants who had responded to kisspeptin with a rise in luteinizing hormone (LH) of 0.8 mIU/mL or greater subsequently progressed through puberty (n = 8). In contrast, all participants who had exhibited LH responses to kisspeptin ≤ 0.4 mIU/mL reached age 18 years without developing physical signs of puberty (n = 8). Thus, responses to kisspeptin accurately predicted later pubertal outcomes (P = .0002). Moreover, the kisspeptin-stimulation test outperformed GnRH-stimulated LH, inhibin B, and genetic testing in predicting pubertal outcomes.

CONCLUSION

The kisspeptin-stimulation can assess future reproductive endocrine potential in prepubertal children and is a promising novel tool for predicting pubertal outcomes for children with delayed puberty.

The effect of sleep duration on hemoglobin and hematocrit: observational and Mendelian randomization study

STUDY OBJECTIVE

Observationally sleep duration is positively associated with hemoglobin (Hgb), whether this association is causal and consistent by sex remains unclear. Here, we assessed the association of sleep duration with Hgb and hematocrit (Hct) observationally in late adolescence in a population-representative Chinese birth cohort "Children of 1997" with validation using Mendelian randomization (MR) in adults.

METHODS

In the "Children of 1997" birth cohort (recruited = 8327, included = 3144), we used multivariable linear regression to assess the adjusted associations of sleep duration (measured as time in bed) with Hgb and Hct at 17.5 years and any sex differences. Using two-sample MR, we assessed the effect of sleep duration on Hgb and Hct, based on 61 single nucleotide polymorphisms (SNPs) applied to genome-wide association studies of Hgb and Hct in adults (n = 361 194).

RESULTS

Observationally, self-reported sleep duration was positively associated with Hct (0.034 standard deviations [SDs] per hour, 95% confidence interval [CI] 0.019 to 0.049), but not with Hgb. Using MR longer sleep increased Hct (0.077 SD per hour, 95% CI 0.035 to 0.119) and Hgb (0.065 SD per hour, 95% CI 0.020 to 0.109) using Mendelian randomization pleiotropy residual sum and outlier (MR PRESSO), with more pronounced associations in men.

CONCLUSIONS

Our novel findings indicate sleep increases both Hgb and Hct, particularly in men, perhaps contributing to its restorative qualities. Potential difference by sex and the implications of these findings warrant investigation.

Sleep Duration and Adiposity in Children and Adults: Observational and Mendelian Randomization Studies

OBJECTIVE

This study used two complementary designs, an observational and a Mendelian randomization (MR) study, to assess whether sleep duration causes adiposity in children and adults.

METHODS

In Hong Kong's "Children of 1997" birth cohort, the adjusted cross-sectional associations of sleep duration with BMI z score and obesity and overweight were assessed at ~11 years of age. Generalized estimating equations were also used to examine longitudinal associations of sleep duration at ~11 years with annual BMI z score and obesity and overweight at about 11 to 16 years of age. Using MR, this study assessed the association of genetically predicted sleep duration, based on 54 single-nucleotide polymorphisms, applied to genetic studies of adiposity in children (n = 35,668), men (n = 152,893), and women (n = 171,977).

RESULTS

Longer sleep was cross-sectionally associated with lower BMI z score at ~11 years of age (-0.13 per category, 95% CI: -0.22 to -0.04) and at about 11 to 16 years of age longitudinally in girls (-0.39, 95% CI: -0.66 to -0.13). Using MR, sleep duration was inversely associated with BMI in children (-0.29 SD per hour, 95% CI: -0.54 to -0.04), but was not clearly associated with BMI in adults, particularly for women.

CONCLUSIONS

A small beneficial effect of sleep on BMI in children cannot be ruled out.

The Relationship Between Progesterone, Sleep, and LH and FSH Secretory Dynamics in Early Postmenarchal Girls

CONTEXT

During puberty, LH pulse frequency increases during sleep; in women, LH pulse frequency slows during sleep in the early/middle follicular phase (FP) of the menstrual cycle. The origin and significance of this developmental transition are unknown.

OBJECTIVE

To determine the relationship between progesterone (P4) exposure, sleep-related slowing of LH pulses in the FP, and the intercycle FSH rise, which promotes folliculogenesis, in early postmenarchal girls.

METHODS

23 girls (gynecologic age 0.4 to 3.5 years) underwent hormone measurements and pelvic ultrasounds during two consecutive cycles and one frequent blood sampling study with concurrent polysomnography during the FP.

RESULTS

Subjects demonstrated one of four patterns during cycle 1 that represent a continuum of P4 exposure: ovulatory cycles with normal or short luteal phase lengths or anovulatory cycles ± follicle luteinization. Peak serum P4 and urine pregnanediol (Pd) in cycle 1 were inversely correlated with LH pulse frequency during sleep in the FP of cycle 2 (r = -0.5; P = 0.02 for both). The intercycle FSH rise and folliculogenesis in cycle 2 were maintained after anovulatory cycles without P4 or Pd exposure or nocturnal slowing of LH pulse frequency in the FP.

CONCLUSIONS

During late puberty, rising P4 levels from follicle luteinization and ovulation may promote a slower LH pulse frequency during sleep in the FP. However, a normal FSH rise and follicle growth can occur in the absence of P4-associated slowing. These studies therefore suggest that an immature LH secretory pattern during sleep is unlikely to contribute to menstrual irregularity in the early postmenarchal years.

Vigilance States: Central Neural Pathways, Neurotransmitters and Neurohormones

BACKGROUND AND OBJECTIVE

The sleep-wake cycle is characterized by a circadian rhythm involving neurotransmitters and neurohormones that are released from brainstem nuclei and hypothalamus. The aim of this review is to analyze the role played by central neural pathways, neurotransmitters and neurohormones in the regulation of vigilance states.

METHOD

We analyzed the literature identifying relevant articles dealing with central neural pathways, neurotransmitters and neurohormones involved in the control of wakefulness and sleep.

RESULTS

The reticular activating system is the key center in the control of the states of wakefulness and sleep via alertness and hypnogenic centers. Neurotransmitters and neurohormones interplay during the dark-light cycle in order to maintain a normal plasmatic concentration of ions, proteins and peripheral hormones, and behavioral state control.

CONCLUSION

An updated description of pathways, neurotransmitters and neurohormones involved in the regulation of vigilance states has been depicted.

Emerging Genetic and Epigenetic Mechanisms Underlying Pubertal Maturation in Adolescence

The adolescent transition begins with the onset of puberty which, upstream in the brain, is initiated by the gonadotropin-releasing hormone (GnRH) pulse generator that activates the release of peripheral sex hormones. Substantial research in human and animal models has revealed a myriad of cellular networks and heritable genes that control the GnRH pulse generator allowing the individual to begin the process of reproductive competence and sexual maturation. Here, we review the latest knowledge in neuroendocrine pubertal research with emphasis on genetic and epigenetic mechanisms underlying the pubertal transition.

Morning basal luteinizing hormone, a good screening tool for diagnosing central precocious puberty

PURPOSE

The standard method used to diagnose central precocious puberty (CPP) is the gonadotropin releasing hormone stimulation test (GnRHST). However, this test is inconvenient for children because it is time-consuming and requires multiple samples. This study aimed to determine the reliability of morning unstimulated luteinizing hormone (mLH) level when screening for CPP, with an emphasis on the influence of diurnal variation.

METHODS

This study included 160 girls with signs of early puberty (SMR 2) under 8 years of age. They were classified as CPP or non-CPP based on their standard GnRHST. The auxological, biochemical, and hormonal characteristics of subjects were retrospectively evaluated. The prognostic value of single morning unstimulated gonadotropin level was examined for use in CPP screening.

RESULTS

Of 160 patients, 121 (75.6%) presented with CPP, and 39 (24.4%) were determined to be prepubertal. The mLH/mFSH (morning unstimulated follicular stimulating hormone) ratio showed significant differences between the 2 groups (P&lt;0.001). The mLH was correlated with GnRHST variables (r=0.532, P&lt;0.001). The mLH cutoff point when screening for CPP was 0.22 IU/L, which had sensitivity and specificity of 69.4% and 82.1%, respectively. In regression analysis, bone age (BA) (odds ratio [OR], 1.018; 95% confidence interval [CI], 0.967-1.071; P=0.506) and body mass index (BMI) (OR, 0.874; 95% CI, 0.583-1.310; P=0.515) were not significant predictors. The mLH≥0.22 IU/L group (OR, 9.596; 95% CI, 3.853-23.900; P&lt;0.001) was highly suggestive of CPP.

CONCLUSION

In this study, single morning unstimulated luteinizing hormone had clinical efficacy for CPP screening, but BA advanced over chronological age and BMI was not useful for CPP screening.

The Emerging Role of Chromatin Remodeling Factors in Female Pubertal Development

To attain sexual competence, all mammalian species go through puberty, a maturational period during which body growth and development of secondary sexual characteristics occur. Puberty begins when the diurnal pulsatile gonadotropin-releasing hormone (GnRH) release from the hypothalamus increases for a prolonged period of time, driving the adenohypophysis to increase the pulsatile release of luteinizing hormone with diurnal periodicity. Increased pubertal GnRH secretion does not appear to be driven by inherent changes in GnRH neuronal activity; rather, it is induced by changes in transsynaptic and glial inputs to GnRH neurons. We now know that these changes involve a reduction in inhibitory transsynaptic inputs combined with increased transsynaptic and glial excitatory inputs to the GnRH neuronal network. Although the pubertal process is known to have a strong genetic component, during the last several years, epigenetics has been implicated as a significant regulatory mechanism through which GnRH release is first repressed before puberty and is involved later on during the increase in GnRH secretion that brings about the pubertal process. According to this concept, a central target of epigenetic regulation is the transcriptional machinery of neurons implicated in stimulating GnRH release. Here, we will briefly review the hormonal changes associated with the advent of female puberty and the role that excitatory transsynaptic inputs have in this process. In addition, we will examine the 3 major groups of epigenetic modifying enzymes expressed in the neuroendocrine hypothalamus, which was recently shown to be involved in pubertal development and progression.

Sex- and sub region-dependent modulation of arcuate kisspeptin neurones by vasopressin and vasoactive intestinal peptide

A population of kisspeptin neurones located in the hypothalamic arcuate nucleus (ARN) very likely represent the gonadotrophin-releasing hormone pulse generator responsible for driving pulsatile luteinising hormone secretion in mammals. As such, it has become important to understand the neural inputs that modulate the activity of ARN kisspeptin (ARN^KISS ) neurones. Using a transgenic GCaMP6 mouse model allowing the intracellular calcium levels ([Ca²⁺ ]_i ) of individual ARN^KISS neurones to be assessed simultaneously, we examined whether the circadian neuropeptides vasoactive intestinal peptide (VIP) and arginine vasopressin (AVP) modulated the activity of ARN^KISS neurones directly. To validate this methodology, we initially evaluated the effects of neurokinin B (NKB) on [Ca²⁺ ]_i in kisspeptin neurones residing within the rostral, middle and caudal ARN subregions of adult male and female mice. All experiments were undertaken in the presence of tetrodotoxin and ionotropic amino acid antagonists. NKB was found to evoke an abrupt increase in [Ca²⁺ ]_i in 95%-100% of kisspeptin neurones throughout the ARN of both sexes. By contrast, both VIP and AVP were found to primarily activate kisspeptin neurones located in the caudal ARN of female mice. Although 58% and 59% of caudal ARN kisspeptin neurones responded to AVP and VIP, respectively, in female mice, only 0%-8% of kisspeptin neurones located in other ARN subregions responded in females and 0%-12% of cells in any subregion in males (P < 0.05). These observations demonstrate unexpected sex differences and marked heterogeneity in functional neuropeptide receptor expression amongst ARN^KISS neurones organised on a rostro-caudal basis. The functional significance of this unexpected influence of VIP and AVP on ARN^KISS neurones remains to be established.

Hypothalamic epigenetics driving female puberty

Puberty involves a series of morphological, physiological and behavioural changes during the last part of the juvenile period that culminates in the attainment of fertility. The activation of the pituitary-gonadal axis by increased hypothalamic secretion of gonadotrophin-releasing hormone (GnRH) is an essential step in the process. The current hypothesis postulates that a loss of transsynaptic inhibition and a rise in excitatory inputs are responsible for the activation of GnRH release. Similarly, a shift in the balance in the expression of puberty activating and puberty inhibitory genes exists during the pubertal transition. In addition, recent evidence suggests that the epigenetic machinery controls this genetic balance, giving rise to the tantalising possibility that epigenetics serves as a relay of environmental signals known for many years to modulate pubertal development. Here, we review the contribution of epigenetics as a regulatory mechanism in the hypothalamic control of female puberty.

Progesterone-Mediated Inhibition of the GnRH Pulse Generator: Differential Sensitivity as a Function of Sleep Status

CONTEXT

During normal, early puberty, luteinizing hormone (LH) pulse frequency is low while awake but increases during sleep. Mechanisms underlying such changes are unclear, but a small study in early pubertal girls suggested that differential wake-sleep sensitivity to progesterone negative feedback plays a role.

OBJECTIVE

To test the hypothesis that progesterone acutely reduces waking LH pulse frequency more than sleep-associated pulse frequency in late pubertal girls.

DESIGN

Randomized, placebo-controlled, double-blinded crossover study.

SETTING

Academic clinical research unit.

PARTICIPANTS

Eleven normal, postmenarcheal girls, ages 12 to 15 years.

INTERVENTION

Subjects completed two 18-hour admissions in separate menstrual cycles (cycle days 6 to 11). Frequent blood sampling for LH assessment was performed at 1800 to 1200 hours; sleep was encouraged at 2300 to 0700 hours. Either oral micronized progesterone (0.8 mg/kg/dose) or placebo was given at 0700, 1500, 2300, and 0700 hours, before and during the first admission. A second admission, performed at least 2 months later, was identical to the first except that placebo was exchanged for progesterone or vice versa (treatment crossover).

MAIN OUTCOME MEASURES

LH pulse frequency during waking and sleeping hours.

RESULTS

Progesterone reduced waking LH pulse frequency by 26% (P = 0.019), with no change observed during sleep (P = 0.314). The interaction between treatment condition (progesterone vs placebo) and sleep status (wake vs sleep) was highly significant (P = 0.007).

CONCLUSIONS

In late pubertal girls, progesterone acutely reduced waking LH pulse frequency more than sleep-associated pulse frequency. Differential wake-sleep sensitivity to progesterone negative feedback may direct sleep-wake LH pulse frequency changes across puberty.

Estrogen directly stimulates LHb expression at the pituitary level during puberty in female zebrafish

The LHb expression is up-regulated during puberty in female zebrafish. However, the molecular mechanism underlying how LHb expression is regulated during puberty remains largely unknown. In this study, we found that the mRNA expression levels of lhb, fshb and cyp19a1b were up-regulated along with the puberty onset in zebrafish. Among the three nuclear estrogen receptors (nERs), the esr2b is the only type whose expression is significantly up-regulated during puberty onset in the pituitary. However, in situ hybridization results revealed that lhb mRNA was colocalized with esr1 and esr2a but not esr2b. Exposure to estradiol (E₂) significantly stimulates LHb expression in both wild-type and kiss1^-/-;kiss2^-/-;gnrh3^-/- triple knockout pubertal zebrafish. Moreover, exposure of cultured pituitary cells to E₂ increased the LHb expression, indicating that the estrogenic effect on LHb expression could be acted at the pituitary level. Finally, we cloned and analyzed the promoter of lhb by luciferase assay. Our results indicated that the E₂ responsive regions of lhb promoter for ERα and ERβ2 are identical, suggesting that ERα and ERβ2 could bind to the same half ERE region of the promoter of lhb, exhibiting a classical ERE-dependent pathway. In summary, we demonstrate that E₂ could directly act on the pituitary level to stimulate LHb transcription during puberty in zebrafish.

Trithorax dependent changes in chromatin landscape at enhancer and promoter regions drive female puberty

Polycomb group (PcG) proteins control the timing of puberty by repressing the Kiss1 gene in hypothalamic arcuate nucleus (ARC) neurons. Here we identify two members of the Trithorax group (TrxG) of modifiers, mixed-lineage leukemia 1 (MLL1), and 3 (MLL3), as central components of an activating epigenetic machinery that dynamically counteracts PcG repression. Preceding puberty, MLL1 changes the chromatin configuration at the promoters of Kiss1 and Tac3, two genes required for puberty to occur, from repressive to permissive. Concomitantly, MLL3 institutes a chromatin structure that changes the functional status of a Kiss1 enhancer from poised to active. RNAi-mediated, ARC-specific Mll1 knockdown reduced Kiss1 and Tac3 expression, whereas CRISPR-Cas9-directed epigenome silencing of the Kiss1 enhancer selectively reduced Kiss1 activity. Both interventions delay puberty and disrupt reproductive cyclicity. Our results demonstrate that an epigenetic switch from transcriptional repression to activation is crucial to the regulatory mechanism controlling the timing of mammalian puberty.

Influence of Sleep Stage on LH Pulse Initiation in the Normal Late Follicular Phase and in Polycystic Ovary Syndrome

OBJECTIVE

During the early follicular phase, sleep-related luteinizing hormone (LH) pulse initiation is positively associated with brief awakenings but negatively associated with rapid eye movement (REM) sleep. The relationship between sleep architecture and LH pulse initiation has not been assessed in other cycle stages or in women with polycystic ovary syndrome (PCOS).

DESIGN AND METHODS

We performed concomitant frequent blood sampling (LH pulse analysis) and polysomnography on 8 normal women (cycle day 7-11) and 7 women with PCOS (at least cycle day 7).

RESULTS

In the normal women, the 5 min preceding LH pulses contained more wake epochs and fewer REM epochs than the 5 min preceding randomly determined time points (wake: 22.3 vs. 9.1%, p = 0.0111; REM: 4.4 vs. 18.8%, p = 0.0162). However, LH pulse initiation was not related to wake or REM epochs in PCOS; instead, the 5 min preceding LH pulses contained more slow-wave sleep (SWS) than the 5 min before random time points (20.9 vs. 6.7%, p = 0.0089). Compared to the normal subjects, the women with PCOS exhibited a higher REM-associated LH pulse frequency (p = 0.0443) and a lower proportion of wake epochs 0-5 min before LH pulses (p = 0.0205).

CONCLUSIONS

Sleep-related inhibition of LH pulse generation during the later follicular phase is normally weakened by brief awakenings and strengthened by REM sleep. In women with PCOS, LH pulse initiation is not appropriately discouraged by REM sleep and may be encouraged by SWS; these abnormalities may contribute to a high sleep-related LH pulse frequency in PCOS.

The Relationship Between Estrogen and the Decline in Delta Power During Adolescence

Study Objectives

During adolescence, there is a precipitous decrease in slow-wave sleep (SWS) and its spectral correlate, delta power, which may reflect cortical reorganization. The temporal association between the decrease in delta power and puberty suggests that sex steroids may initiate these changes. This association has not been previously investigated.

Methods

To determine whether estrogen triggers the adolescent decline in delta power, we compared delta power in 14 girls with central precocious puberty (CPP) and 6 age-matched, prepubertal controls. Five CPP participants were re-studied 7-14 months after pubertal suppression to determine if the changes in delta power are reversible after restoring a prepubertal hormonal milieu. The change in delta power was also compared between CPP participants and five historic controls from a longitudinal polysomnographic study.

Results

CPP participants (6.7-10.5 years) spent 30% of the night in SWS. Delta power (3.7 × 106 ± 2.7 × 105 µV2) predominated in the first 2 non-rapid eye movement episodes and decayed exponentially (tau 0.006 minutes). Age-matched controls demonstrated similar sleep staging (24% SWS) and delta dynamics (3.3 × 106 ± 5.1 × 105 µV2, tau 0.004 minutes). Four out of 5 CPP participants had a significant decrease (26%) in delta power after hormone suppression (p < .05), similar to historic controls.

Conclusion

Using an innovative model of girls with CPP studied before and after estrogen suppression, the effects of puberty on the decline in delta power were dissociated from those of chronologic age. The current studies suggest that increased estrogen does not cause the adolescent decline in delta power and indicate that neurodevelopmental changes per se or other factors associated with puberty drive these sleep changes.

Overview of Sleep and Sleep Disorders in Infancy and Childhood

Sleep in children is an important and dynamic process, affecting numerous aspects of health and development. Problems with sleep are relatively common but often can be challenging to recognize. This article reviews the fundamental aspects of sleep in children from infancy to adolescence, and the most common and relevant sleep disorders likely to be encountered in a general pediatric practice. Where available, current evidence-based recommendations for management are discussed, including indications for referral to a sleep specialist. [Pediatr Ann. 2017;46(4):e133-e138.].

Puberty and structural brain development in humans

Adolescence is a transitional period of physical and behavioral development between childhood and adulthood. Puberty is a distinct period of sexual maturation that occurs during adolescence. Since the advent of magnetic resonance imaging (MRI), human studies have largely examined neurodevelopment in the context of age. A breadth of animal findings suggest that sex hormones continue to influence the brain beyond the prenatal period, with both organizational and activational effects occurring during puberty. Given the animal evidence, human MRI research has also set out to determine how puberty may influence otherwise known patterns of age-related neurodevelopment. Here we review structural-based MRI studies and show that pubertal maturation is a key variable to consider in elucidating sex- and individual- based differences in patterns of human brain development. We also highlight the continuing challenges faced, as well as future considerations, for this vital avenue of research.

Control of puberty onset and fertility by gonadotropin-releasing hormone neurons

The gonadotropin-releasing hormone (GnRH) neuronal network generates pulse and surge modes of gonadotropin secretion critical for puberty and fertility. The arcuate nucleus kisspeptin neurons that innervate the projections of GnRH neurons in and around their neurosecretory zone are key components of the pulse generator in all mammals. By contrast, kisspeptin neurons located in the preoptic area project to GnRH neuron cell bodies and proximal dendrites and are involved in surge generation in female rodents (and possibly other species). The hypothalamic-pituitary-gonadal axis develops embryonically but, apart from short periods of activation immediately after birth, remains suppressed through a combination of gonadal and non-gonadal mechanisms. At puberty onset, the pulse generator reactivates, probably owing to progressive stimulatory influences on GnRH neurons from glial and neurotransmitter signalling, and the re-emergence of stimulatory arcuate kisspeptin input. In females, the development of pulsatile gonadotropin secretion enables final maturation of the surge generator that ultimately triggers the first ovulation. Representation of the GnRH neuronal network as a series of interlocking functional modules could help conceptualization of its functioning in different species. Insights into pulse and surge generation are expected to aid development of therapeutic strategies ameliorating pubertal disorders and infertility in the clinic.

Neuroendocrine control of the onset of puberty

This chapter is based on the Geoffrey Harris Memorial Lecture presented at the 8th International Congress of Neuroendocrinology, which was held in Sydney, August 2014. It provides the development of our understanding of the neuroendocrine control of puberty since Harris proposed in his 1955 monograph (Harris, 1955) that "a major factor responsible for puberty is an increased rate of release of pituitary gonadotrophin" and posited "that a neural (hypothalamic) stimulus, via the hypophysial portal vessels, may be involved." Emphasis is placed on the neurobiological mechanisms governing puberty in highly evolved primates, although an attempt is made to reverse translate a model for the timing of puberty in man and monkey to non-primate species.

Accumulated deep sleep is a powerful predictor of LH pulse onset in pubertal children

CONTEXT

During puberty, reactivation of the reproductive axis occurs during sleep, with LH pulses specifically tied to deep sleep. This association suggests that deep sleep may stimulate LH secretion, but there have been no interventional studies to determine the characteristics of deep sleep required for LH pulse initiation.

OBJECTIVE

The objective of this study was to determine the effect of deep sleep fragmentation on LH secretion in pubertal children.

DESIGN AND SETTING

Studies were performed in a clinical research center.

SUBJECTS

Fourteen healthy pubertal children (11.3-14.1 y) participated in the study.

INTERVENTIONS

Subjects were randomized to two overnight studies with polysomnography and frequent blood sampling, with or without deep sleep disruption via auditory stimuli.

RESULTS

An average of 68.1 ±10.7 (± SE) auditory stimuli were delivered to interrupt deep sleep during the disruption night, limiting deep sleep to only brief episodes (average length disrupted 1.3 ± 0.2 min vs normal 7.1 ± 0.8 min, P < .001), and increasing the number of transitions between non-rapid eye movement (NREM), REM, and wake (disrupted 274.5 ± 33.4 vs normal 131.2 ± 8.1, P = .001). There were no differences in mean LH (normal: 3.2 ± 0.4 vs disrupted: 3.2 ± 0.5 IU/L), LH pulse frequency (0.6 ± 0.06 vs 0.6 ± 0.07 pulses/h), or LH pulse amplitude (2.8 ± 0.4 vs 2.8 ± 0.4 IU/L) between the two nights. Poisson process modeling demonstrated that the accumulation of deep sleep in the 20 minutes before an LH pulse, whether consolidated or fragmented, was a significant predictor of LH pulse onset (P < .001).

CONCLUSION

In pubertal children, nocturnal LH augmentation and pulse patterning are resistant to deep sleep fragmentation. These data suggest that, even when fragmented, deep sleep is strongly related to activation of the GnRH pulse generator.

Impact of BMI on gonadorelin-stimulated LH peak in premenarcheal girls with idiopathic central precocious puberty

OBJECTIVE

To clarify the impact of body mass index (BMI) on luteinizing hormone (LH) secretion in response to gonadorelin (GnRH) stimulation testing in girls diagnosed with idiopathic central precocious puberty (ICPP).

METHODS

Retrospective single-center cohort study was carried out in 865 confirmed ICPP girls who underwent GnRH stimulation tests. Pubertal development according to Tanner, sex hormone parameters, and LH secretion in response to GnRH-stimulation was compared.

RESULTS

Around 609 girls were of normal weight (70.4%), while 168 children (19.4%) were overweight, and 88 (10.2%) were obese. Peak LH levels after GnRH were much higher in the normal-weight group, with a median of 9.1 mIU ml(-1) (interquartile 5.2-13.1), compared with the median peak LH in the overweight and obese groups (8.5 mIU ml(-1), interquartile 5.3-11.6, and 6.2 mIU ml(-1), interquartile 5.3-11.0, respectively P < 0.001 for all comparisons). Peak LH/FSH ratio was also lower in the obese group (median 0.6, interquartile 0.68-0.90) compared with the normal-weight (median 0.8, interquartile 0.61-1.11) and overweight (median 0.8, interquartile 0.64-0.92) groups.

CONCLUSIONS

Higher BMI is associated with lower LH response to GnRH-stimulation testing in girls with ICPP. It is recommended that BMI should be considered when interpreting GnRH-stimulation tests.

Epigenetic regulation of female puberty

Substantial progress has been made in recent years toward deciphering the molecular and genetic underpinnings of the pubertal process. The availability of powerful new methods to interrogate the human genome has led to the identification of genes that are essential for puberty to occur. Evidence has also emerged suggesting that the initiation of puberty requires the coordinated activity of gene sets organized into functional networks. At a cellular level, it is currently thought that loss of transsynaptic inhibition, accompanied by an increase in excitatory inputs, results in the pubertal activation of GnRH release. This concept notwithstanding, a mechanism of epigenetic repression targeting genes required for the pubertal activation of GnRH neurons was recently identified as a core component of the molecular machinery underlying the central restraint of puberty. In this chapter we will discuss the potential contribution of various mechanisms of epigenetic regulation to the hypothalamic control of female puberty.

Blunted day-night changes in luteinizing hormone pulse frequency in girls with obesity: the potential role of hyperandrogenemia

CONTEXT

Puberty is marked by sleep-associated changes in LH pulse frequency and amplitude. Early pubertal girls with obesity exhibit blunted day-to-night changes in LH secretion; whether this occurs in late pubertal obese girls is unknown.

OBJECTIVE

The objective of the study was to test two hypotheses: 1) blunted day-to-night changes in LH secretion occur in both early and late pubertal obese girls, and 2) such alterations are specifically associated with hyperandrogenemia.

DESIGN

This was a cross-sectional analysis.

SETTING

The study was conducted at a clinical research center.

PATIENTS OR OTHER PARTICIPANTS

Twenty-seven early pubertal, premenarcheal girls (12 of whom were obese) and 63 late pubertal (postmenarcheal) girls (27 of whom were obese) participated in the study.

INTERVENTION

Blood samples were taken every 10 minutes from 7:00 pm to 7:00 am.

MAIN OUTCOME MEASURE

Change in LH pulse frequency [LH interpulse interval (IPI)] from daytime hours (7:00 pm-11:00 pm, while awake) to nighttime hours (11:00 pm to 7:00 am, while generally asleep).

RESULTS

Both nonobese and obese postmenarcheal girls demonstrated significant day-to-night decreases in LH pulse frequency (IPI increases of 33% and 16%, respectively), but day-to-night changes were blunted in obese girls (P = .004, obese vs nonobese). Day-to-night LH pulse frequency decreased significantly in postmenarcheal obese subjects with normal T concentrations (26% IPI increase) but not in those with hyperandrogenemia. Similar differences were evident for LH pulse amplitude. Nonobese and obese early pubertal girls exhibited nonsignificant differences in day-night LH pulse frequency (day to night IPI increase of 26% vs decrease of 1%, respectively).

CONCLUSIONS

Day-to-night changes in LH pulse secretion are blunted in postmenarcheal obese adolescent girls. This phenomenon may in part reflect hyperandrogenemia.

Obstructive sleep apnea (OSA) in preadolescent girls is associated with delayed breast development compared to girls without OSA

STUDY OBJECTIVE

Adults with obstructive sleep apnea (OSA) have lower sex steroid levels than controls. We sought to determine whether OSA also interferes with reproductive hormones in adolescence by tracking the pace of pubertal development.

METHODS

One hundred seventy-two children in the Tucson Children's Assessment of Sleep Apnea study (TuCASA) underwent two home polysomnographic studies, spaced 4-5 years apart. Height and weight were measured at both visits, and Tanner staging of breasts/genitals and pubic hair were self-assessed by a pictorial questionnaire at follow-up.

RESULTS

Eighty-seven girls and 85 boys, age 8.9 ± 1.6 years (mean ± SD) at baseline and 13.4 ± 1.6 years at follow-up, participated. Twenty-seven percent of participants were over-weight or obese at baseline, and the majority remained so at follow-up. Twenty-six percent of girls and 28% of boys met criteria for OSA, defined as a respiratory disturbance index (RDI) ≥ 1/h associated with a 3% desaturation (RDI 3%), at baseline. There was an inverse relationship between baseline log RDI 3% and Tanner breast stage at follow-up (coefficient -1.3, p = 0.02) in girls after adjusting for age (p < 0.001), body mass index (p < 0.005), and ethnicity. Girls with OSA at baseline were more than 1 Tanner breast stage behind girls without OSA at follow-up. OSA did not affect genital development in boys or pubic hair development in either sex.

CONCLUSIONS

OSA in preadolescent girls predicts delayed breast development relative to girls without OSA. Sleep fragmentation and/or hypoxia seen in OSA may interfere with reproductive development in girls.

Comparison of detection of normal puberty in girls by a hormonal sleep test and a gonadotropin-releasing hormone agonist test

CONTEXT

The magnitude of sleep-related gonadotropin rise required to activate pubertal feminization is not established.

OBJECTIVE

The objective of the study was to determine the normal relationship of pubertal hormone responses to sleep and to GnRH agonist (GnRHag) challenge across the female pubertal transition.

DESIGN/SETTING

This was a prospective study in a General Clinical Research Center.

PARTICIPANTS

Sixty-two healthy 6- to 13-year-old volunteer girls participated in the study.

INTERVENTIONS

Interventions included overnight blood sampling followed by GnRHag (leuprolide acetate) injection.

PRIMARY OUTCOME VARIABLES

The primary outcome variables included LH, FSH, and estradiol.

RESULTS

LH levels rose steadily during sleep and after GnRHag throughout the prepubertal years. The LH response to sleep and GnRHag correlated well across groups (eg, r = 0.807, peak vs 4 h post-GnRHag value); however, this correlation was less robust than in boys (r = 0.964, P < .01). Sleep peak LH of 1.3 U/L or greater had 85% sensitivity and 2.1 U/L or greater 96% specificity for detecting puberty (thelarche). The LH 1-hour post-GnRHag value of 3.2 U/L or greater had 95% sensitivity and 5.5 U/L or greater 96% specificity for detecting puberty. Girls entered puberty at lower LH levels than boys. FSH levels rose day and night during the prepubertal years to reach 1.0 U/L or greater during puberty but discriminated puberty poorly. Estradiol of 34 pg/mL or greater at 20-24 hours after GnRHag was 95% sensitive and 60 pg/mL or greater was 95% specific for puberty. Thirty-six percent of overweight early pubertal girls had meager hormonal evidence of puberty.

CONCLUSIONS

These data suggest that sleep-related pubertal hormone levels critical for puberty are normally reflected in the responses to GnRHag testing across the normal female pubertal transition. Inconsistencies between clinical and hormonal staging may arise from peripubertal cyclicity of neuroendocrine function and from excess adiposity.

The atrazine metabolite diaminochlorotriazine suppresses LH release from murine LβT2 cells by suppressing GnRH-induced intracellular calcium transients

The primary metabolite of the herbicide atrazine (ATRA), diaminochlorotriazine (DACT), has been suggested to cause disruption in the hypothalamic-pituitary-gonadal axis leading to inhibition of luteinizing hormone (LH) release. DACT is a reactive electrophile known to form covalent protein adducts both in vitro and in vivo following ATRA exposure and maybe targeting proteins involved in GnRH-induced calcium signaling and subsequent LH release. To test this hypothesis, LβT2 pituitary cells were exposed to 300 μM DACT for 24 hrs and examined by fluorescence microscopy for GnRH-induced changes in intracellular calcium and LH release. LβT2 cells exposed to DACT had markedly diminished GnRH-induced intracellular calcium transients and a significant decreased LH release in response to GnRH. DACT appeared to cause a selective decrease in caffeine-sensitive ryanodine receptor-operated calcium stores in LβT2 cells, rather than in thapsigargin-sensitive ER calcium stores. This sensitivity correlated with the formation of covalent protein adducts by DACT, as determined by mass spectrometry. ERp57 was identified by mass spectrometry as a target of DACT adduction in the ER that could potentially mediate the effects of DACT on inhibition of GnRH-induced calcium signaling and inhibition of LH release. Intracellular calcium responses to GnRH and release of LH were restored in DACT-treated cells with the addition of a calcium ionophore (A23187). These data suggest that DACT forms adducts on proteins involved in calcium handling within the ER and that dysfunction in this critical signaling system is associated with loss of normal sensitivity to GnRH and subsequent decreased release of LH.

Comparison of detection of normal puberty in boys by a hormonal sleep test and a gonadotropin-releasing hormone agonist test

CONTEXT

The magnitude of sleep-related gonadotropin rise required to activate pubertal gonadal function is not established.

OBJECTIVE

Our objective was to determine the normal relationship between sleep-related pubertal hormone levels and pituitary-testicular responsiveness to a GnRH agonist (GnRHag) test across the pubertal transition. DESIGN/SETTING AND PARTICIPANTS: We conducted a prospective study in a General Clinical Research Center with healthy 9- to 15-yr-old volunteer boys.

INTERVENTIONS

INTERVENTIONS included overnight blood sampling followed by leuprolide acetate injection (10 μg/kg).

PRIMARY OUTCOME VARIABLES

LH, FSH, and testosterone levels were evaluated.

RESULTS

LH levels during sleep and post-GnRHag rose steadily during the late prepubertal years. Sleep peak LH correlated highly with the LH response to GnRHag across groups (r = 0.913). A sleep peak LH level of at least 3.7 U/liter predicted pubertal testicular activation with 100% accuracy. LH of at least 14.8 and at least 19.0 U/liter 4 h after GnRHag, respectively, predicted puberty with 100% sensitivity/94% specificity and 100% specificity/94% sensitivity. Overweight pubertal boys had transiently prolonged responses to GnRHag. FSH rose during both waking and sleeping hours during the prepubertal years, and all pubertal boys had an FSH level of at least 0.9 U/liter awake and at least 1.2 U/liter asleep. Sleep LH was more closely related than FSH to testicular size.

CONCLUSIONS

These data suggest that a critical LH level during sleep (≥3.7 U/liter) heralds the onset of pubertal virilization and that this level is predictable by LH of at least 14.8-19 U/liter 4 h after GnRHag. These data also suggest that LH stimulation of testicular androgen production plays a role in stimulating testicular tubule growth once a critical level of FSH is achieved.

Insights into puberty: the relationship between sleep stages and pulsatile LH secretion

CONTEXT

During the pubertal transition, LH secretion initially increases only during sleep; however, its relationship to sleep stage is unknown.

OBJECTIVES

Our objective was to determine whether the initiation of LH pulses is related to a specific sleep stage in pubertal children.

DESIGN AND SETTING

Frequent blood sampling and polysomnographic studies were performed in a Clinical Research Center.

SUBJECTS

Fourteen studies were performed in nine healthy pubertal children, ages 9.9-15.6 yr.

INTERVENTIONS

Subjects underwent one to two overnight studies with polysomnography and blood sampling for LH at 10-min intervals.

RESULTS

Alignment of polysomnographic records and LH pulses demonstrated that LH pulses (n = 58) occurred most frequently during slow-wave sleep (SWS) (1.1 pulse/h, n = 30) compared with all other sleep stages or periods of wake after sleep onset (P < 0.001). There was also a significant increase in the amount of SWS in the 15 min preceding and the 5 min following each pulse compared with the amount of SWS seen across the study night (P < 0.01).

CONCLUSIONS

During puberty, the majority of LH pulses that occur after sleep onset are preceded by SWS, suggesting that SWS is intimately involved in the complex control of pubertal onset. These studies raise concerns about the potential hormonal repercussions of the increasing prevalence of sleep disturbances in adolescents.

Thyroid transcription factor 1, a homeodomain containing transcription factor, contributes to regulating periodic oscillations in GnRH gene expression

Thyroid transcription factor 1 (TTF1), a member of the Nkx family of transcription factors required for basal forebrain morphogenesis, functions in the postnatal hypothalamus as a transcriptional regulator of genes encoding neuromodulators and hypophysiotrophic peptides. One of these peptides is gonadotrophin-releasing hormone (GnRH). In the present study, we show that Ttf1 mRNA abundance varies in a diurnal and melatonin-dependent fashion in the preoptic area of the rat, with maximal Ttf1 expression attained during the dark phase of the light/dark cycle, preceding the nocturnal peak in GnRH mRNA content. GnRH promoter activity oscillates in a circadian manner in GT1-7 cells, and this pattern is enhanced by TTF1 and blunted by small interfering RNA-mediated Ttf1 gene silencing. TTF1 transactivates GnRH transcription by binding to two sites in the GnRH promoter. Rat GnRH neurones in situ contain key proteins components of the positive (BMAL1, CLOCK) and negative (PER1) limbs of the circadian oscillator, and these proteins repress Ttf1 promoter activity in vitro. By contrast, Ttf1 transcription is activated by CRY1, a clock component required for circadian rhythmicity. In turn, TTF1 represses transcription of Rev-erbα, a heme receptor that controls circadian transcription within the positive limb of the circadian oscillator. These findings suggest that TTF1 is a component of the molecular machinery controlling circadian oscillations in GnRH gene transcription.

Developmental increase in kisspeptin-54 release in vivo is independent of the pubertal increase in estradiol in female rhesus monkeys (Macaca mulatta)

Kisspeptin (KP) signaling has been proposed as an important regulator in the mechanism of puberty. In this study, to determine the role of KP in puberty, we assessed the in vivo release pattern of KP-54 from the basal hypothalamus/stalk-median eminence in prepubertal and pubertal ovarian-intact female rhesus monkeys. We found that there was a developmental increase in mean KP-54 release, pulse frequency, and pulse amplitude, which is parallel to the developmental changes in GnRH release that we previously reported. Moreover, a nocturnal increase in KP-54 release becomes prominent after the onset of puberty. Because the pubertal increase in GnRH release occurs independent of the pubertal increase in circulating gonadal steroids, we further examined whether ovariectomy (OVX) modifies the release pattern of KP-54. Results show that OVX in pubertal monkeys enhanced mean KP-54 release and pulse amplitude but not pulse frequency, whereas OVX did not alter the release pattern of KP-54 in prepubertal monkeys. Estradiol replacement in OVX pubertal monkeys suppressed mean KP-54 release and pulse amplitude but not pulse frequency. Estradiol replacement in OVX prepubertal monkeys did not alter the KP-54 release pattern. Collectively these results suggest that the pubertal increase in KP release occurs independent of the pubertal increase in circulating estradiol. Nevertheless, the pubertal increase in KP release is not likely responsible for the initiation of the pubertal increase in GnRH release. Rather, after puberty onset, the increase in KP release contributes to further increase GnRH release during the progression of puberty.

Neuroendocrinology-based therapy for Alzheimer's disease

The nervous system interacts directly with the endocrine system to control a plethora of central nervous system (CNS) functions. Metabolic and reproductive hormones are known to be important in the maintenance of neuronal health and their fluctuations are important for CNS aspects ranging from sleep and appetite regulation to cognitive function. This review will summarize and critically evaluate how age-related changes in sex and metabolic hormones modulate affect cognitive function and the implications of targeting the neuroendocrinological system as a therapeutic strategy in Alzheimer's disease.

Differential sleep-wake sensitivity of gonadotropin-releasing hormone secretion to progesterone inhibition in early pubertal girls

CONTEXT

Early pubertal luteinizing hormone (LH), and by inference gonadotropin-releasing hormone (GnRH), pulse secretion is marked by high nocturnal but low daytime frequency; however, the underlying mechanisms remain unclear. Plasma concentrations of progesterone, the major regulator of GnRH frequency in women, increase in the early morning in early pubertal girls and may help slow daytime GnRH frequency.

OBJECTIVE

To evaluate the effect of progesterone on LH pulse frequency in early to mid-pubertal girls.

DESIGN

Controlled interventional study.

SETTING

General clinical research center.

PARTICIPANTS

Eighteen non-obese, non-hyperandrogenemic Tanner 1-3 girls.

INTERVENTION

Twelve-hour (19:00-07:00 h) blood sampling with or without oral progesterone administration (25-50 mg at 16:00 and 20:00 h).

MAIN OUTCOME MEASURE

LH pulse frequency.

RESULTS

Girls receiving progesterone (n = 5) exhibited lower 12-hour LH pulse frequency than controls (n = 13), but this difference was not statistically significant (average interpulse intervals 196.0 ± 61.9 and 160.4 ± 67.1 min, respectively; p = 0.2793). In contrast to controls, however, girls receiving progesterone exhibited no LH pulses during waking hours (19:00-23:00 h; estimated interpulse interval 326.0 ± 52.7 vs. 212.0 ± 120.9 min; p = 0.0376), while nighttime (23:00-07:00 h) interpulse intervals were similar (174.8 ± 62.0 vs. 167.5 ± 76.9 min, respectively; p = 0.7750).

CONCLUSIONS

Exogenous progesterone acutely suppressed daytime, but not nocturnal, LH pulse frequency in early to mid-pubertal girls, suggesting that GnRH pulse frequency is differentially regulated by progesterone depending on sleep status.

Etiology and treatment of hypogonadism in adolescents

Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. The causes of hypogonadism are heterogeneous and may involve any level of the reproductive system. This review discusses various causes of hypogonadism, describes the evaluation of hypogonadal states, and outlines treatment options for the induction of puberty in affected adolescents. Whereas some conditions are clearly delineated, the exact etiology and underlying pathogenesis of many disorders is unknown.