Absence of circadian rhythms of gonadotropin secretion in women

Effects of pulsatile intravenous follicle-stimulating hormone treatment on ovarian function in women with obesity

OBJECTIVE

To establish conditions for effective hypothalamic suppression in women with normal and high body mass index (BMI) and test the hypothesis that intravenous (IV) administration of pulsatile recombinant follicle-stimulating hormone (rFSH) can overcome the clinically evident dysfunctional pituitary-ovarian axis in women with obesity.

DESIGN

Prospective interventional study.

SETTING

Academic medical center.

PATIENT(S)

Twenty-seven normal-weight women and 27 women with obesity, who were eumenorrheic and aged 21-39 years.

INTERVENTION(S)

Two-day frequent blood sampling study, in early follicular phase, before and after cetrorelix suppression of gonadotropins and exogenous pulsatile IV rFSH administration.

MAIN OUTCOME MEASURE(S)

Serum inhibin B and estradiol (E2) levels (basal and rFSH stimulated).

RESULT(S)

A modified gonadotropin-releasing hormone antagonism protocol effectively suppressed production of endogenous gonadotropins in women with normal and high BMIs, providing a model to address the functional role of FSH in the hypothalamic-pituitary-ovarian axis. The IV rFSH treatment resulted in equivalent serum levels and pharmacodynamics in normal-weight women and those with obesity. However, women with obesity exhibited reduced basal levels of inhibin B and E2 and a significantly decreased response to FSH stimulation. The BMI was inversely correlated with serum inhibin B and E2. In spite of this observed deficit in ovarian function, pulsatile IV rFSH treatment in women with obesity resulted in E2 and inhibin B levels comparable with those in normal-weight women, in the absence of exogenous FSH stimulation.

CONCLUSION(S)

Despite normalization of FSH levels and pulsatility by exogenous IV administration, women with obesity demonstrate ovarian dysfunction with respect to E2 and inhibin B secretion. Pulsatile FSH can partially correct the relative hypogonadotropic hypogonadism of obesity, thereby providing a potential treatment strategy to mitigate some of the adverse effects of high BMI on fertility, assisted reproduction, and pregnancy outcomes.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov #NCT02478775.

Physiological Rhythms and Biological Variation of Biomolecules: The Road to Personalized Laboratory Medicine

The concentration of biomolecules in living systems shows numerous systematic and random variations. Systematic variations can be classified based on the frequency of variations as ultradian (<24 h), circadian (approximately 24 h), and infradian (>24 h), which are partly predictable. Random biological variations are known as between-subject biological variations that are the variations among the set points of an analyte from different individuals and within-subject biological variation, which is the variation of the analyte around individuals’ set points. The random biological variation cannot be predicted but can be estimated using appropriate measurement and statistical procedures. Physiological rhythms and random biological variation of the analytes could be considered the essential elements of predictive, preventive, and particularly personalized laboratory medicine. This systematic review aims to summarize research that have been done about the types of physiological rhythms, biological variations, and their effects on laboratory tests. We have searched the PubMed and Web of Science databases for biological variation and physiological rhythm articles in English without time restrictions with the terms “Biological variation, Within-subject biological variation, Between-subject biological variation, Physiological rhythms, Ultradian rhythms, Circadian rhythm, Infradian rhythms”. It was concluded that, for effective management of predicting, preventing, and personalizing medicine, which is based on the safe and valid interpretation of patients’ laboratory test results, both physiological rhythms and biological variation of the measurands should be considered simultaneously.

The Influence of Ketone Bodies on Circadian Processes Regarding Appetite, Sleep and Hormone Release: A Systematic Review of the Literature

Chrononutrition is an emerging branch of chronobiology focusing on the profound interactions between biological rhythms and metabolism. This framework suggests that, just like all biological processes, even nutrition follows a circadian pattern. Recent findings elucidated the metabolic roles of circadian clocks in the regulation of both hormone release and the daily feeding–fasting cycle. Apart from serving as energy fuel, ketone bodies play pivotal roles as signaling mediators and drivers of gene transcription, promoting food anticipation and loss of appetite. Herein we provide a comprehensive review of the literature on the effects of the ketogenic diets on biological processes that follow circadian rhythms, among them appetite, sleep, and endocrine function.

Kisspeptin-neuron control of LH pulsatility and ovulation

Feedback from oestradiol (E2) plays a critical role in the regulation of major events in the physiological menstrual cycle including the release of gonadotrophins to stimulate follicular growth, and the mid-cycle luteinising hormone (LH) surge that leads to ovulation. E2 predominantly exerts its action via oestrogen receptor-alpha (ERα), however, as gonadotrophin releasing hormone (GnRH) neurons lack ERα, E2-feedback is posited to be indirectly mediated via upstream neurons. Kisspeptin (KP) is a neuropeptide expressed in hypothalamic KP-neurons that control GnRH secretion and plays a key role in the central mechanism regulating the hypothalamic-pituitary-gonadal (HPG) axis. In the rodent arcuate (ARC) nucleus, KP is co-expressed with Neurokinin B and Dynorphin; and thus, these neurons are termed 'Kisspeptin-Neurokinin B-Dynorphin' (KNDy) neurons. ARC KP-neurons function as the 'GnRH pulse generator' to regulate GnRH pulsatility, as well as mediating negative feedback from E2. A second KP neuronal population is present in the rostral periventricular area of the third ventricle (RP3V), which includes anteroventral periventricular (AVPV) nucleus and preoptic area neurons. These RP3V KP-neurons mediate positive feedback to induce the mid-cycle luteinising hormone (LH) surge and subsequent ovulation. Here, we describe the role of KP-neurons in these two regions in mediating this differential feedback from oestrogens. We conclude by considering reproductive diseases for which exploitation of these mechanisms could yield future therapies.

The circadian system: From clocks to physiology

The circadian system, composed of the central autonomous clock, the suprachiasmatic nucleus (SCN), and systems of the body that follow the signals of the SCN, continuously change the homeostatic set points of the body over the day-night cycle. Changes in the body's physiological state that do not agree with the time of the day feedback to the hypothalamus, and provide input to the SCN to adjust the condition, thus reaching another set point required by the changed conditions. This allows the adjustment of the set points to another level when environmental conditions change, which is thought to promote adaptation and survival. In fasting, the body temperature drops to a lower level only at the beginning of the sleep phase. Stressful conditions raise blood pressure relatively more during the active period than during the rest phase. Extensive, mostly reciprocal SCN interactions, with hypothalamic networks, induce these physiological adjustments by hormonal and autonomic control of the body's organs. More importantly, in addition to SCN's hormonal and autonomic influences, SCN induced behavior, such as rhythmic food intake, induces the oscillation of many genes in all tissues, including the so-called clock genes, which have an essential role as a transcriptional driving force for numerous cellular processes. Consequently, the light-dark cycle, the rhythm of the SCN, and the resulting rhythm in behavior need to be perfectly synchronized, especially where it involves synchronizing food intake with the activity phase. If these rhythms are not synchronous for extended periods of times, such as during shift work, light exposure at night, or frequent night eating, disease may develop. As such, our circadian system is a perfect illustration of how hypothalamic-driven processes depend on and interact with each other and need to be in seamless synchrony with the body's physiology.

Vasopressinergic Activity of the Suprachiasmatic Nucleus and mRNA Expression of Clock Genes in the Hypothalamus-Pituitary-Gonadal Axis in Female Aging

The important involvement of the suprachiasmatic nucleus (SCN) and the activity of vasopressinergic neurons in maintaining the rhythmicity of the female reproductive system depends on the mRNA transcription-translation feedback loops. Therefore, circadian clock function, like most physiological processes, is involved in the events that determine reproductive aging. This study describes the change of mRNA expression of clock genes, Per2, Bmal1, and Rev-erbα, in the hypothalamus-pituitary-gonadal axis (HPG) of female rats with regular cycle (RC) and irregular cycle (IC), and the vasopressinergic neurons activity in the SCN and kisspeptin neurons in the arcuate nucleus (ARC) of these animals. Results for gonadotropins and the cFos/AVP-ir neurons in the SCN of IC were higher, but kisspeptin-ir was minor. Change in the temporal synchrony of the clock system in the HPG axis, during the period prior to the cessation of ovulatory cycles, was identified. The analysis of mRNA for Per2, Bmal1, and Rev-erbα in the reproductive axis of adult female rodents shows that the regularity of the estrous cycle is guaranteed by alternation in the amount of expression of Bmal1 and Per2, and Rev-erbα and Bmal1 between light and dark phases, which ceases to occur and contributes to determining reproductive senescence. These results showed that the desynchronization between the central and peripheral circadian clocks contributes to the irregularity of reproductive events. We suggest that the feedback loops of clock genes on the HPG axis modulate the spontaneous transition from regular to irregular cycle and to acyclicity in female rodents.

Meta-Analysis Comparing Menstrual Regularity and Dysmenorrhea of Women Working Rotating Shifts and Fixed Day Shifts

Background: Rotating shift work can cause abnormalities in their endocrine system. We conducted a meta-analysis to gain a better understanding of the differences between women working rotating shifts and fixed day shifts in menstrual regularity and dysmenorrhea. Methods: We searched for studies containing relevant keywords that were published between 1990 and 2019 in the Cochrane Library, EBSCO (including the Cumulative Index to Nursing and Allied Health Literature [CINAHL]), MEDLINE, and ProQuest. Data analysis was performed using the software package Comprehensive Meta-Analysis (CMA) Version 3.0. Results: A total of 14 studies met our selection criteria. The pooled odds ratio (OR) comparing the menstrual irregularity of women working rotating shifts and fixed day shifts was 1.35 (95% confidence interval [CI]: 1.28-1.42, p < 0.001). The pooled OR of the women aged 30 years or older was 1.35 (95% CI: 1.28-1.42, p < 0.001); and for the women under 30 years old, the pooled OR was 1.66 (95% CI: 1.13-2.44, p = 0.010). The pooled OR comparing the dysmenorrhea occurrence among women working rotating shifts and fixed day shifts was 1.51 (95% CI: 0.87-2.62, p = 0.139). The pooled OR of the women aged 30 years or older was 2.35 (95% CI: 1.63-3.39, p < 0.001); and for the women under 30 years old, the pooled OR was 1.20 (95% CI: 0.61-2.33, p = 0.601). Conclusions: The results indicate that regardless of age, women working rotating shifts were more likely to experience menstrual irregularity than those working fixed day shifts. With regard to dysmenorrhea, among women aged 30 years or older, those working rotating shifts were also more likely to experience dysmenorrhea than those working fixed day shifts.

An examination of the relationship between sunlight exposure and hot flush in working women

We examined whether sunlight affects hot flushes in working menopausal women and explored effect modification by shift work and season. In this prospective cohort study, daily hot flush score (outcome) was measured by the 7-day North Central Cancer Treatment Group Daily Vasomotor Symptoms Diary. Daily duration of sunlight (≥2000 lux) was recorded by the HOBO MX2202 pendant. Both variables were measured in two 7-day data collection phases. T0 data were collected during the Australian Summer (December 2017, January and February 2018); and T1 data were collected in the Australian winter (June, July and August 2018). Linear mixed effects model was used. Shift work and season were both confounders and effect modifiers. To detect a median effect size of R² = 0.2, 34 women were required to achieve an effective sample size of 41. A total of 49 menopausal women were recruited, 11 shift and 38 day workers. Some 13 women had various missing observations. For shift workers, an hour increase in sunlight exposure was associated with a 1.4-point reduction in hot flush score (p = .016). This relationship was not significant for day workers (p = .185). The finding of this study suggests increased sunlight exposure might improve hot flushes in menopausal shift workers who are moderately bothered by hot flushes, but probably not in day workers. The possible role of shift-work associated circadian disruption on estrogen level in regard to elevated intensity and frequency of hot flush in menopausal women is discussed.

Endogenous Circadian Regulation of Female Reproductive Hormones

CONTEXT

Studies suggest that female reproductive hormones are under circadian regulation, although methodological differences have led to inconsistent findings.

OBJECTIVE

To determine whether circulating levels of reproductive hormones exhibit circadian rhythms.

DESIGN

Blood samples were collected across ∼90 consecutive hours, including 2 baseline days under a standard sleep-wake schedule and ∼50 hours of extended wake under constant routine (CR) conditions.

SETTING

Intensive Physiological Monitoring Unit, Brigham and Women's Hospital.

PARTICIPANTS

Seventeen healthy premenopausal women (22.8 ± 2.6 years; nine follicular; eight luteal).

INTERVENTIONS

Fifty-hour CR.

MAIN OUTCOME MEASURES

Plasma estradiol (E2), progesterone (P4), LH, FSH, SHBG, melatonin, and core body temperature.

RESULTS

All hormones exhibited significant 24-hour rhythms under both standard sleep-wake and CR conditions during the follicular phase (P < 0.05). In contrast, only FSH and SHBG were significantly rhythmic during the luteal phase. Rhythm acrophases and amplitudes were similar between standard sleep-wake and CR conditions. The acrophase occurred in the morning for P4; in the afternoon for FSH, LH, and SHBG; and during the night for E2.

CONCLUSIONS

Our results confirm previous reports of ∼24-hour rhythms in many female reproductive hormones in humans under ambulatory conditions but demonstrate that these hormones are under endogenous circadian regulation, defined as persisting in the absence of external time cues. These results may have important implications for the effects of circadian disruption on reproductive function.

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.

A prospective, randomized study comparing morning to evening administration of gonadotropins in ART

OBJECTIVE

We sought to determine whether administering the daily gonadotropin dose in the morning (AM) or in the evening (PM) affects cycle outcome in patients undergoing IVF.

DESIGN

This is a prospective randomized study.

SETTING

The study is performed in a private assisted reproductive technology (ART) clinic.

PATIENT(S)

The study included one hundred and twenty-seven women undergoing IVF.

INTERVENTION(S)

Morning (AM) and evening (PM) administration of gonadotropins (uFSH and hMG) was compared.

MAIN OUTCOME MEASURE(S)

Live birth rate was the main outcome measured. Secondary outcomes including total IU use, days of stimulation, peak E₂, peak P₄, endometrial thickness, number of oocytes retrieved, MII oocytes, fertilization rates, #ET, IR, and clinical PR were all assessed.

RESULTS

A total of 127 cycles were included, 61 in the AM group and 67 in the PM group. Baseline and stimulation characteristics were similar in both groups. There was a trend for a higher implantation rate in the AM group vs. the PM group (60.3 vs. 47.2%, P = 0.066). The AM group had a higher chemical pregnancy rate compared to the PM group (81.7 vs. 65.6%, P = 0.024) and a higher clinical pregnancy rate (78.3 vs. 62.1%, P = 0.048), but the delivery rates were similar (68.3 vs. 56.1%, P = 0.16). The study was unfortunately prematurely terminated when uFSH (Bravelle©) was pulled out of the US market.

CONCLUSIONS

AM administration of gonadotropins may be associated with a better ART outcome compared to PM administration. Larger studies are needed to confirm our findings.

Pharmacokinetics and Pharmacodynamics of Follicle-Stimulating Hormone in Healthy Women Receiving Single and Multiple Doses of Highly Purified Human Menotrophin and Urofollitrophin

BACKGROUND AND OBJECTIVE

Highly purified human menotrophin and urofollitrophin preparations obtained from human urine via a novel patented purification method have been tested over a timeframe of 14 years in the studies presented in this article. The objective of the studies was to investigate the pharmacokinetics and the pharmacodynamics of follicle-stimulating hormone (FSH) after single subcutaneous and intramuscular doses and multiple subcutaneous doses of the tested preparations in healthy fertile pituitary-suppressed women.

DESIGNS

We performed five open, randomised, crossover, single-dose bioequivalence and/or bioavailability studies and one open, multiple-dose, pharmacokinetics and pharmacodynamics study.

STUDY SUBJECTS AND TREATMENTS

The six studies included 121 healthy fertile women taking their usual combined oral contraceptives for 3 months before the study: Study 1: 300 international units (IU) of highly purified menotrophin as single subcutaneous and intramuscular doses. Study 2: 300 IU of highly purified menotrophin (test formulation vs. comparator) as single subcutaneous doses. Study 3: 300 IU of highly purified urofollitrophin (hp-FSH) (test formulation vs. comparator) as single subcutaneous doses. Study 4: 300 IU (2 × 150 IU vs. 4 × 75 IU) of hp-FSH as single subcutaneous doses. Study 5: 225 and 445 IU of hp-FSH as single subcutaneous doses. Study 6: daily 225 IU of hp-FSH as subcutaneous doses for 5 consecutive days.

MAIN OUTCOME MEASURES

The main outcome measures were the FSH pharmacokinetic parameters, estradiol concentrations, and the number and size of the follicles.

RESULTS

FSH after single subcutaneous and intramuscular injections of menotrophin or urofollitrophin attained a systemic peak (maximum) concentration (C _max) that was on average consistent throughout the first four studies and ranged from 4.98 to 7.50 IU/L. The area under the plasma concentration-time curve (AUC) from administration to the last observed concentration time t (AUC_t) ranged from 409.71 to 486.16 IU/L·h and the elimination half-life (t _½) ranged from 39.02 to 53.63 h. After multiple doses of urofollitrophin (225 IU) for 5 days, FSH attained a mean C _max of 14.93 ± 2.92 IU/L and had an AUC during the time interval τ between two consecutive doses at steady state (AUC_τ) of 322.59 ± 57.92 IU/L·h, which was similar to the mean AUC_t after a single subcutaneous dose of 225 IU of urofollitrophin in study 5 (306.82 ± 68.37 IU/L·h).

CONCLUSIONS

In our studies, the intramuscular and subcutaneous routes of menotrophin were equivalent; both menotrophin and urofollitrophin were bioequivalent to their marketed reference; FSH kinetic parameters following injection of urofollitrophin were dose proportional and independent from the administered concentration; and multiple doses of FSH increased estradiol levels and enhanced growth of follicles with a good dose-response correlation. Local tolerability was excellent throughout the six studies.

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.

Diurnal Variation of Hormonal and Lipid Biomarkers in a Molecular Epidemiology-Like Setting

Introduction

Many molecular epidemiology studies focusing on high prevalent diseases, such as metabolic disorders and cancer, investigate metabolic and hormonal markers. In general, sampling for these markers can occur at any time-point during the day or after an overnight fast. However, environmental factors, such as light exposure and food intake might affect the levels of these markers, since they provide input for the internal time-keeping system. When diurnal variation is larger than the inter-individual variation, time of day should be taken into account. Importantly, heterogeneity in diurnal variation and disturbance of circadian rhythms among a study population might increasingly occur as a result of our increasing 24/7 economy and related variation in exposure to environmental factors (such as light and food).

Aim

The aim of the present study was to determine whether a set of often used biomarkers shows diurnal variation in a setting resembling large molecular epidemiology studies, i.e., non-fasted and limited control possibilities for other environmental influences.

Results

We show that markers for which diurnal variation is not an issue are adrenocorticotropic hormone, follicle stimulating hormone, estradiol and high-density lipoprotein. For all other tested markers diurnal variation was observed in at least one gender (cholesterol, cortisol, dehydroepiandrosterone sulfate, free fatty acids, low-density lipoprotein, luteinizing hormone, prolactin, progesterone, testosterone, triglycerides, total triiodothyronine and thyroid-stimulating hormone) or could not reliably be detected (human growth hormone).

Discussion

Thus, studies investigating these markers should take diurnal variation into account, for which we provide some options. Furthermore, our study indicates the need for investigating diurnal variation (in literature or experimentally) before setting up studies measuring markers in routine and controlled settings, especially since time-of-day likely matters for many more markers than the ones investigated in the present study.

Sleep, sleep disturbance, and fertility in women

Sleep and sleep disturbances are increasingly recognized as determinants of women's health and well-being, particularly in the context of the menstrual cycle, pregnancy, and menopause. At present, however, little is known about whether fertility is affected by sleep quantity and quality. That is, to what degree, and by what mechanisms, do sleep and/or its disturbances affect fertility? The purpose of this review is to synthesize what is known about sleep disturbances in relation to reproductive capacity. A model is provided, whereby stress, sleep dysregulation, and circadian misalignment are delineated for their potential relevance to infertility. Ultimately, if it is the case that sleep disturbance is associated with infertility, new avenues for clinical intervention may be possible.

Circadian clock control of endocrine factors

Organisms experience dramatic fluctuations in demands and stresses over the course of the day. In order to maintain biological processes within physiological boundaries, mechanisms have evolved for anticipation of, and adaptation to, these daily fluctuations. Endocrine factors have an integral role in homeostasis. Not only do circulating levels of various endocrine factors oscillate over the 24 h period, but so too does responsiveness of target tissues to these signals or stimuli. Emerging evidence suggests that these daily endocrine oscillations do not occur solely in response to behavioural fluctuations associated with sleep-wake and feeding-fasting cycles, but are orchestrated by an intrinsic timekeeping mechanism known as the circadian clock. Disruption of circadian clocks by genetic and/or environmental factors seems to precipitate numerous common disorders, including the metabolic syndrome and cancer. Collectively, these observations suggest that strategies designed to realign normal circadian rhythmicities hold potential for the treatment of various endocrine-related disorders.

Sex and the migraine brain

The brain responds differently to environmental and internal signals that relate to the stage of development of neural systems. While genetic and epigenetic factors contribute to a premorbid state, hormonal fluctuations in women may alter the set point of migraine. The cyclic surges of gonadal hormones may directly alter neuronal, glial and astrocyte function throughout the brain. Estrogen is mainly excitatory and progesterone inhibitory on brain neuronal systems. These changes contribute to the allostatic load of the migraine condition that most notably starts at puberty in girls.

Influence of ovarian manipulation on reproductive endocrinology in polycystic ovarian syndrome and regularly cycling women

OBJECTIVE

Little is known about the function of the ovarian neuronal network in humans. In many species, copulation influences endocrinology through this network. As a first step, the possible influence of ovarian mechanical manipulation on pituitary and ovarian hormones was evaluated in polycystic ovarian syndrome (PCOS) and regularly cycling women.

DESIGN

Prospective case-control study (2008-2010).

METHODS

Ten PCOS women (Rotterdam criteria) undergoing ovulation induction with recombinant-FSH and ten normal ovulatory controls were included in an academic fertility clinic. In the late follicular phase blood was drawn every 10 min for 6 h. After 3 h the ovaries were mechanically manipulated by moving a transvaginal ultrasound probe firmly over each ovary ten times. Main outcome measures were LH and FSH pulsatility and ovarian hormones before and after ovarian manipulation.

RESULTS

All PCOS patients showed an LH decline after the ovarian manipulation (before 13.0 U/l and after 10.4 U/l, P<0.01), probably based on a combination of a longer LH pulse interval and smaller amplitude (P=0.07). The controls showed no LH change (before 9.6 U/l and after 9.3 U/l, P=0.67). None of the ovarian hormones (estradiol, progesterone, anti-Müllerian hormone, inhibin B, androstenedione and testosterone) changed in either group.

CONCLUSIONS

Ovarian mechanical manipulation lowers LH secretion immediately and typically only in preovulatory PCOS patients. The immediate LH change after the ovarian manipulation without any accompanying ovarian hormonal changes point to nonhormonal communication from the ovaries to the pituitary. A neuronal pathway from the ovaries communicating to the hypothalamic-pituitary system is the most reasonable explanation.

Clinical review: Adolescent anovulation: maturational mechanisms and implications

CONTEXT

Adolescents are at high risk for menstrual dysfunction. The diagnosis of anovulatory disorders that may have long-term health consequences is too often delayed.

EVIDENCE ACQUISITION

A review of the literature in English was conducted, and data were summarized and integrated from the author's perspective.

MAIN FINDINGS

Normal adolescent anovulation causes only minor menstrual cycle irregularity: most cycles range from 21-45 days, even in the first postmenarcheal year, 90% by the fourth year. Approximately half of symptomatic menstrual irregularity is due to neuroendocrine immaturity, and half is associated with increased androgen levels. The former is manifest as aluteal or short/deficient luteal phase cycles and usually resolves spontaneously. The latter seems related to polycystic ovary syndrome because adolescent androgen levels are associated with adult androgens and ovulatory dysfunction, but data are sparse. Obesity causes hyperandrogenemia and, via unclear mechanisms, seems to suppress LH; it may mimic polycystic ovary syndrome. The role of pubertal insulin resistance in physiological adolescent anovulation is unclear. High-sensitivity gonadotropin and steroid assays, the latter by specialty laboratories, are necessary for accurate diagnosis of pubertal disorders. Polycystic ovaries are a normal ultrasonographic finding in young women and are associated with nearly 2-fold increased anti-Müllerian hormone levels. Oral contraceptives are generally the first-line treatment for ongoing menstrual dysfunction, and the effects of treatment are similar among preparations.

CONCLUSIONS

Menstrual cycle duration persistently outside 21-45 days in adolescents is unusual, and persistence ≥ 1 year suggests that disordered hypothalamic-pituitary-gonadal function be considered. Research is needed on the mechanisms and prognosis of adolescent anovulation.

Shift work and circadian dysregulation of reproduction

Health impairments, including reproductive issues, are associated with working nights or rotating shifts. For example, shift work has been associated with an increased risk of irregular menstrual cycles, endometriosis, infertility, miscarriage, low birth weight or pre-term delivery, and reduced incidence of breastfeeding. Based on what is known about circadian regulation of endocrine rhythms in rodents (and much less in humans), the circadian clock is an integral regulatory part of the reproductive system. When this 24-h program is disordered by environmental perturbation (such as shift work) or genetic alterations, the endocrine system can be impaired. The purpose of this review is to explore the hypothesis that misalignment of reproductive hormones with the environmental light-dark cycle and/or sleep-wake rhythms can disrupt menstrual cycles, pregnancy, and parturition. We highlight the role of the circadian clock in regulating human reproductive physiology and shift work-induced pathology within each step of the reproductive axis while exploring potential mechanisms from the animal model literature. In addition to documenting the reproductive hazards of shift work, we also point out important gaps in our knowledge as critical areas for future investigation. For example, future studies should examine whether forced desynchronization disrupts gonadotropin secretion rhythms and whether there are sleep/wake schedules that are better or worse for the adaptation of the reproductive system to shift work. These studies are necessary in order to define not only whether or not shift work-induced circadian misalignment impairs reproductive capacity, but also to identify strategies for the future that can minimize this desynchronization.

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.

A comparison of the neuroendocrine mechanisms underlying the initiation of the preovulatory LH surge in the human, Old World monkey and rodent

As recognized for decades, the role of the rodent hypothalamus in timing the LH surge is deterministic and mediated by a GnRH discharge that is generated by an obligatory interaction in the preoptic area (POA) between a threshold level of estradiol and a circadian neural signal: a view consistent with contemporary kisspeptinocentric models of the estrous cycle. In higher primates, generation of the LH surge is emancipated from control by the POA. Woman represents the exemplar of the system in higher primates, as the LH surge appears to unfold in the absence of a midcycle GnRH discharge being generated instead by facilitatory interaction between a pulsatile GnRH input to the pituitary and an action of ovarian estradiol. The neurobiology of GnRH pulse generation is only beginning to emerge but from a translational perspective this aspect of hypothalamic function is critical for understanding the human menstrual cycle and how it may be perturbed.