Inhibiting Kiss1 Neurons With Kappa Opioid Receptor Agonists to Treat Polycystic Ovary Syndrome and Vasomotor Symptoms

GnRH pulse generator activity in mouse models of polycystic ovary syndrome

One in ten women in their reproductive age suffer from polycystic ovary syndrome (PCOS) that, alongside subfertility and hyperandrogenism, typically presents with increased luteinizing hormone (LH) pulsatility. As such, it is suspected that the arcuate kisspeptin (ARNKISS) neurons that represent the GnRH pulse generator are dysfunctional in PCOS. We used here in vivo GCaMP fiber photometry and other approaches to examine the behavior of the GnRH pulse generator in two mouse models of PCOS. We began with the peripubertal androgen (PPA) mouse model of PCOS but found that it had a reduction in the frequency of ARNKISS neuron synchronization events (SEs) that drive LH pulses. Examining the prenatal androgen (PNA) model of PCOS, we observed highly variable patterns of pulse generator activity with no significant differences detected in ARNKISS neuron SEs, pulsatile LH secretion, or serum testosterone, estradiol, and progesterone concentrations. However, a machine learning approach identified that the ARNKISS neurons of acyclic PNA mice continued to exhibit cyclical patterns of activity similar to that of normal mice. The frequency of ARNKISS neuron SEs was significantly increased in algorithm-identified 'diestrous stage' PNA mice compared to controls. In addition, ARNKISS neurons exhibited reduced feedback suppression to progesterone in PNA mice and their gonadotrophs were also less sensitive to GnRH. These observations demonstrate the importance of understanding GnRH pulse generator activity in mouse models of PCOS. The existence of cyclical GnRH pulse generator activity in the acyclic PNA mouse indicates the presence of a complex phenotype with deficits at multiple levels of the hypothalamo-pituitary-gonadal axis.

POMC neurons control fertility through differential signaling of MC4R in Kisspeptin neurons

Inactivating mutations in the melanocortin 4 receptor (MC4R) gene cause monogenic obesity. Interestingly, female patients also display various degrees of reproductive disorders, in line with the subfertile phenotype of MC4RKO female mice. However, the cellular mechanisms by which MC4R regulates reproduction are unknown. Kiss1 neurons directly stimulate gonadotropin-releasing hormone (GnRH) release through two distinct populations; the Kiss1ARH neurons, controlling GnRH pulses, and the sexually dimorphic Kiss1AVPV/PeN neurons controlling the preovulatory LH surge. Here, we show that Mc4r expressed in Kiss1 neurons regulates fertility in females. In vivo, deletion of Mc4r from Kiss1 neurons in female mice replicates the reproductive impairments of MC4RKO mice without inducing obesity. Conversely, reinsertion of Mc4r in Kiss1 neurons of MC4R null mice restores estrous cyclicity and LH pulsatility without reducing their obese phenotype. In vitro, we dissect the specific action of MC4R on Kiss1ARH vs Kiss1AVPV/PeN neurons and show that MC4R activation excites Kiss1ARH neurons through direct synaptic actions. In contrast, Kiss1AVPV/PeN neurons are normally inhibited by MC4R activation except under elevated estradiol levels, thus facilitating the activation of Kiss1AVPV/PeN neurons to induce the LH surge driving ovulation in females. Our findings demonstrate that POMCARH neurons acting through MC4R, directly regulate reproductive function in females by stimulating the "pulse generator" activity of Kiss1ARH neurons and restricting the activation of Kiss1AVPV/PeN neurons to the time of the estradiol-dependent LH surge, and thus unveil a novel pathway of the metabolic regulation of fertility by the melanocortin system.

Non-hormonal pharmacological interventions for managing vasomotor symptoms-how can we help: 2024 landscape

BACKGROUND

Vasomotor symptoms (VMS) affect 70% of menopausal women and are considered as hallmark symptoms of the menopausal transition experienced by over three quarters of women and severely by 25% of women. Estrogen withdrawal alone is not fully responsible for the onset of the menopausal vasomotor symptoms and the mechanism of altered thermoregulation appears to be centrally mediated with alterations in hypothalamic neurotransmitters playing a key part. The loss of thermoregulatory control coexists with the altered Kisspeptin- Neurokinin B-Dynorphin-expressing (KNDy) neurons of the arcuate nucleus signaling triggered by menopause.

OBJECTIVE

Aim of the review was to explore evidence-based non-hormonal pharmacological interventions for treating vasomotor symptoms.

METHODS

Comprehensive overview of relevant literature.

CONCLUSIONS

In the population where, hormonal options are contraindicated or not preferred by the patient, it is essential to explore evidence-based non-hormonal pharmacological interventions for treating vasomotor symptoms. The 2024 landscape of available treatments has expanded yet again, arming the providers with an even wider range of possibilities to help their patients. Fezolinetant, is the first NK3R antagonist developed for the purpose of treating hot flashes in menopausal women. NK3R antagonists provide a safe and effective treatment option for managing menopausal women with VMS.

Screening and identification of key biomarkers associated with endometriosis using bioinformatics and next-generation sequencing data analysis

Background

Endometriosis is a common cause of endometrial-type mucosa outside the uterine cavity with symptoms such as painful periods, chronic pelvic pain, pain with intercourse and infertility. However, the early diagnosis of endometriosis is still restricted. The purpose of this investigation is to identify and validate the key biomarkers of endometriosis.

Methods

Next-generation sequencing dataset GSE243039 was obtained from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between endometriosis and normal control samples were identified. After screening of DEGs, gene ontology (GO) and REACTOME pathway enrichment analyses were performed. Furthermore, a protein–protein interaction (PPI) network was constructed and modules were analyzed using the Human Integrated Protein–Protein Interaction rEference database and Cytoscape software, and hub genes were identified. Subsequently, a network between miRNAs and hub genes, and network between TFs and hub genes were constructed using the miRNet and NetworkAnalyst tool, and possible key miRNAs and TFs were predicted. Finally, receiver operating characteristic curve analysis was used to validate the hub genes.

Results

A total of 958 DEGs, including 479 upregulated genes and 479 downregulated genes, were screened between endometriosis and normal control samples. GO and REACTOME pathway enrichment analyses of the 958 DEGs showed that they were mainly involved in multicellular organismal process, developmental process, signaling by GPCR and muscle contraction. Further analysis of the PPI network and modules identified 10 hub genes, including vcam1, snca, prkcb, adrb2, foxq1, mdfi, actbl2, prkd1, dapk1 and actc1. Possible target miRNAs, including hsa-mir-3143 and hsa-mir-2110, and target TFs, including tcf3 (transcription factor 3) and clock (clock circadian regulator), were predicted by constructing a miRNA-hub gene regulatory network and TF-hub gene regulatory network.

Conclusions

This investigation used bioinformatics techniques to explore the potential and novel biomarkers. These biomarkers might provide new ideas and methods for the early diagnosis, treatment and monitoring of endometriosis.

Targeted inhibition of kisspeptin neurons reverses hyperandrogenemia and abnormal hyperactive LH secretion in a preclinical mouse model of polycystic ovary syndrome

STUDY QUESTION

Do hyperactive kisspeptin neurons contribute to abnormally high LH secretion and downstream hyperandrogenemia in polycystic ovary syndrome (PCOS)-like conditions and can inhibition of kisspeptin neurons rescue such endocrine impairments?

SUMMARY ANSWER

Targeted inhibition of endogenous kisspeptin neuron activity in a mouse model of PCOS reduced the abnormally hyperactive LH pulse secretion and hyperandrogenemia to healthy control levels.

WHAT IS KNOWN ALREADY

PCOS is a reproductive disorder characterized by hyperandrogenemia, anovulation, and/or polycystic ovaries, along with a hallmark feature of abnormal LH hyper-pulsatility, but the mechanisms underlying the endocrine impairments remain unclear. A chronic letrozole (LET; aromatase inhibitor) mouse model recapitulates PCOS phenotypes, including polycystic ovaries, anovulation, high testosterone, and hyperactive LH pulses. LET PCOS-like females also have increased hypothalamic kisspeptin neuronal activation which may drive their hyperactive LH secretion and hyperandrogenemia, but this has not been tested.

STUDY DESIGN, SIZE, DURATION

Transgenic KissCRE+/hM4Di female mice or littermates Cre- controls were treated with placebo, or chronic LET (50 µg/day) to induce a PCOS-like phenotype, followed by acute (once) or chronic (2 weeks) clozapine-N-oxide (CNO) exposure to chemogenetically inhibit kisspeptin cells (n = 6 to 10 mice/group).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Key endocrine measures, including in vivo LH pulse secretion patterns and circulating testosterone levels, were assessed before and after selective kisspeptin neuron inhibition and compared between PCOS groups and healthy controls. Alterations in body weights were measured and pituitary and ovarian gene expression was determined by qRT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

Acute targeted inhibition of kisspeptin neurons in PCOS mice successfully lowered the abnormally hyperactive LH pulse secretion (P < 0.05). Likewise, chronic selective suppression of kisspeptin neuron activity reversed the previously high LH and testosterone levels (P < 0.05) down to healthy control levels and rescued reproductive gene expression (P < 0. 05).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Ovarian morphology was not assessed in this study. Additionally, mouse models can offer mechanistic insights into neuroendocrine processes in PCOS-like conditions but may not perfectly mirror PCOS in women.

WIDER IMPLICATIONS OF THE FINDINGS

These data support the hypothesis that overactive kisspeptin neurons can drive neuroendocrine PCOS-like impairments, and this may occur in PCOS women. Our findings complement recent clinical investigations using NKB receptor antagonists to lower LH in PCOS women and suggest that pharmacological dose-dependent modulation of kisspeptin neuron activity may be a valuable future therapeutic target to clinically treat hyperandrogenism and lower elevated LH in PCOS women.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by NIH grants R01 HD111650, R01 HD090161, R01 HD100580, P50 HD012303, R01 AG078185, and NIH R24 HD102061, and a pilot project award from the British Society for Neuroendocrinology. There are no competing interests.

New advances in menopause symptom management

Vasomotor symptoms (VMS) are characteristic of menopause experienced by over 75% of postmenopausal women with significant health and socioeconomic implications. Although the average duration of symptoms is seven years, 10% of women experience symptoms for more than a decade. Although menopausal hormone therapy (MHT) remains an efficacious and cost-effective treatment, its use may not be suitable in all women, such as those at an increased risk of breast cancer or gynaecological malignancy. The neurokinin B (NKB) signaling pathway, together with its intricate connection to the median preoptic nucleus (MnPO), has been postulated to provide integrated reproductive and thermoregulatory responses, with a central role in mediating postmenopausal VMS. This review describes the physiological hypothalamo-pituitary-ovary (HPO) axis, and subsequently the neuroendocrine changes that occur with menopause using evidence derived from animal and human studies. Finally, data from the latest clinical trials using novel therapeutic agents that antagonise NKB signaling are reviewed.

Overactivation of GnRH neurons is sufficient to trigger polycystic ovary syndrome-like traits in female mice

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder leading to anovulatory infertility. Abnormalities in the central neuroendocrine system governed by gonadotropin-releasing hormone (GnRH) neurons might be related to ovarian dysfunction in PCOS, although the link in this disordered brain-to-ovary communication remains unclear. Here, we manipulated GnRH neurons using chemogenetics in adult female mice to unveil whether chronic overaction of these neurons would trigger PCOS-like hormonal and reproductive impairments.

METHODS

We used adult Gnrh1cre female mice to selectively target and express the designer receptors exclusively activated by designer drugs (DREADD)-based chemogenetic tool hM3D(Gq) in hypophysiotropic GnRH neurons. Chronic chemogenetic activation protocol was carried out with clozapine N-oxide (CNO) i.p. injections every 48 h over a month. We evaluated the reproductive and hormonal profile before, during, and two months after chemogenetic manipulations.

FINDINGS

We discovered that the overactivation of GnRH neurons was sufficient to disrupt reproductive cycles, promote hyperandrogenism, and induce ovarian dysfunction. These PCOS features were detected with a long-lasting neuroendocrine dysfunction through abnormally high luteinizing hormone (LH) pulse secretion. Additionally, the GnRH-R blockade prevented the establishment of long-term neuroendocrine dysfunction and androgen excess in these animals.

INTERPRETATION

Taken together, our results show that hyperactivity of hypothalamic GnRH neurons is a major driver of reproductive and hormonal impairments in PCOS and suggest that antagonizing the aberrant GnRH signaling could be an efficient therapeutic venue for the treatment of PCOS.

FUNDING

European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement n◦ 725149).

Endogenous opiates and behavior: 2022

This paper is the forty-fifth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2022 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Polycystic ovary syndrome: pathophysiology and therapeutic opportunities

Polycystic ovary syndrome is characterised by excessive levels of androgens and ovulatory dysfunction, and is a common endocrine disorder in women of reproductive age. Polycystic ovary syndrome arises as a result of polygenic susceptibility in combination with environmental influences that might include epigenetic alterations and in utero programming. In addition to the well recognised clinical manifestations of hyperandrogenism and ovulatory dysfunction, women with polycystic ovary syndrome have an increased risk of adverse mental health outcomes, pregnancy complications, and cardiometabolic disease. Unlicensed treatments have limited efficacy, mostly because drug development has been hampered by an incomplete understanding of the underlying pathophysiological processes. Advances in genetics, metabolomics, and adipocyte biology have improved our understanding of key changes in neuroendocrine, enteroendocrine, and steroidogenic pathways, including increased gonadotrophin releasing hormone pulsatility, androgen excess, insulin resistance, and changes in the gut microbiome. Many patients with polycystic ovary syndrome have high levels of 11-oxygenated androgens, with high androgenic potency, that might mediate metabolic risk. These advances have prompted the development of new treatments, including those that target the neurokinin-kisspeptin axis upstream of gonadotrophin releasing hormone, with the potential to lessen adverse clinical sequelae and improve patient outcomes.

The 2023 nonhormone therapy position statement of The North American Menopause Society

OBJECTIVE

To update the evidence-based Nonhormonal Management of Menopause-Associated Vasomotor Symptoms: 2015 Position Statement of The North American Menopause Society.

METHODS

An advisory panel of clinicians and research experts in women's health were selected to review and evaluate the literature published since the Nonhormonal Management of Menopause-Associated Vasomotor Symptoms: 2015 Position Statement of The North American Menopause Society. Topics were divided into five sections for ease of review: lifestyle; mind-body techniques; prescription therapies; dietary supplements; and acupuncture, other treatments, and technologies. The panel assessed the most current and available literature to determine whether to recommend or not recommend use based on these levels of evidence: Level I, good and consistent scientific evidence; Level II, limited or inconsistent scientific evidence, and Level III, consensus and expert opinion.

RESULTS

Evidence-based review of the literature resulted in several nonhormone options for the treatment of vasomotor symptoms. Recommended: Cognitive-behavioral therapy, clinical hypnosis, selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitors, gabapentin, fezolinetant (Level I); oxybutynin (Levels I-II); weight loss, stellate ganglion block (Levels II-III). Not recommended: Paced respiration (Level I); supplements/herbal remedies (Levels I-II); cooling techniques, avoiding triggers, exercise, yoga, mindfulness-based intervention, relaxation, suvorexant, soy foods and soy extracts, soy metabolite equol, cannabinoids, acupuncture, calibration of neural oscillations (Level II); chiropractic interventions, clonidine; (Levels I-III); dietary modification and pregabalin (Level III).

CONCLUSION

Hormone therapy remains the most effective treatment for vasomotor symptoms and should be considered in menopausal women within 10 years of their final menstrual periods. For women who are not good candidates for hormone therapy because of contraindications (eg, estrogen-dependent cancers or cardiovascular disease) or personal preference, it is important for healthcare professionals to be well informed about nonhormone treatment options for reducing vasomotor symptoms that are supported by the evidence.

Polycystic Ovary Syndrome: Past, Present and Future

Early mentions of PCOS as a disorder can be traced back to ancient history [...].

Recent advances in emerging PCOS therapies

Polycystic ovary syndrome is a prevalent endocrinopathy involving androgen excess, and anovulatory infertility. The disorder is also associated with many comorbidities such as obesity and hyperinsulinemia, and an increased risk of cardiovascular complications. Reproductive, endocrine, and metabolic symptoms are highly variable, with heterogenous phenotypes adding complexity to clinical management of symptoms. This review highlights recent findings regarding emerging therapies for treating polycystic ovary syndrome, including i) pharmacological agents to target androgen excess, ii) modulation of kisspeptin signalling to target central neuroendocrine dysregulation, and iii) novel insulin sensitisers to combat peripheral metabolic dysfunction.

Current and emerging drug treatment strategies for polycystic ovary syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common hormonal, metabolic, and reproductive disorder with a heterogeneous phenotype. As the exact etiology of PCOS is still unclear, available pharmacotherapies are mostly directed toward alleviating symptoms and associated metabolic abnormalities.

AREAS COVERED

Herein, we present an overview of the current and emerging pharmacotherapies for the management of women with PCOS who do not seek pregnancy. We performed a literature search in PubMed database up to January 2022 and reviewed papers assessing drug treatments for PCOS. We aimed to outline the most recent evidence to support treatment recommendations in these patients.

EXPERT OPINION

Targets for medical treatment include hormonal, reproductive, and metabolic abnormalities in PCOS. However, none of the available pharmacological options can cover the entire spectrum of clinical manifestations observed in these patients. Considering the heterogeneity of PCOS, treatment should be individualized and adapted to specific needs of each patient. Better understanding of the molecular mechanisms underlying the pathogenesis of PCOS would help development of novel, safer, and more effective multi-targeted therapeutic strategies for the syndrome.

Invited review: Translating kisspeptin and neurokinin B biology into new therapies for reproductive health

The reproductive neuropeptide kisspeptin has emerged as the master regulator of mammalian reproduction due to its key roles in the initiation of puberty and the control of fertility. Alongside the tachykinin neurokinin B and the endogenous opioid dynorphin, these peptides are central to the hormonal control of reproduction. Building on the expanding body of experimental animal models, interest has flourished with human studies revealing that kisspeptin administration stimulates physiological reproductive hormone secretion in both healthy men and women, as well as patients with common reproductive disorders. In addition, emerging therapeutic roles based on neurokinin B for the management of menopausal flushing, endometriosis and uterine fibroids are increasingly recognised. In this review, we focus on kisspeptin and neurokinin B and their potential application as novel clinical strategies for the management of reproductive disorders.

Impaired steroid hormone feedback in polycystic ovary syndrome: Evidence from preclinical models for abnormalities within central circuits controlling fertility

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy and cause of infertility in women of reproductive age worldwide. Despite diagnostic features of anovulation, polycystic ovarian morphology, and high androgen secretion indicating the syndrome are the result of ovarian dysfunction, alterations to central neuroendocrine circuits that control reproductive capacity may drive PCOS symptoms. Resistance of gonadotrophin-releasing hormone (GnRH) neurons in the hypothalamus to inhibition by sex steroid hormone-negative feedback leads to a rapid frequency of pulsatile gonadotrophin secretion, which, in turn, drives the ovarian features of the disease. As GnRH neurons do not express steroid hormone receptors, impaired negative feedback is hypothesized to occur within an upstream network that controls GnRH pulse generation. This review will discuss the latest work from preclinical animal models of PCOS used to dissect the specific central mechanisms involved in impaired steroid hormone feedback. In particular, this review will focus on research that indicates neurons in the arcuate nucleus of the hypothalamus that express Kisspeptin, Neurokinin B and Dynorphin (KNDy cells) or γ-aminobutyric acid are targets of androgen-mediated impairment of steroid hormone feedback. Finally, this review will explore the development of therapeutic agents targeting neurons that control LH pulse frequency to resolve PCOS symptoms in the clinic.

Treatments targeting neuroendocrine dysfunction in polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age and is the leading cause of anovulatory subfertility. Increased gonadotrophin releasing hormone (GnRH) pulsatility in the hypothalamus results in preferential luteinizing hormone (LH) secretion from the pituitary gland, leading to ovarian hyperandrogenism and oligo/anovulation. The resultant hyperandrogenism reduces negative feedback from sex steroids such as oestradiol and progesterone to the hypothalamus, and thus perpetuates the increase in GnRH pulsatility. GnRH neurons do not have receptors for oestrogen, progesterone, or androgens, and thus the disrupted feedback is hypothesized to occur via upstream neurons. Likely candidates for these upstream regulators of GnRH neuronal pulsatility are Kisspeptin, Neurokinin B (NKB), and Dynorphin neurons (termed KNDy neurons). Growing insight into the neuroendocrine dysfunction underpinning the heightened GnRH pulsatility seen in PCOS has led to research on the use of pharmaceutical agents that specifically target the activity of these KNDy neurons to attenuate symptoms of PCOS. This review aims to highlight the neuroendocrine abnormalities that lead to increased GnRH pulsatility in PCOS, and outline data on recent therapeutic advancements that could potentially be used to treat PCOS. Emerging evidence has investigated the use of neurokinin 3 receptor (NK3R) antagonists as a method of reducing GnRH pulsatility and alleviating features of PCOS such as hyperandrogenism. We also consider other potential mechanisms by which increased GnRH pulsatility is controlled, which could form the basis of future avenues of research.

The role of gonadotropin-releasing hormone neurons in polycystic ovary syndrome

Given the critical central role of gonadotropin-releasing hormone (GnRH) neurons in fertility, it is not surprising that the GnRH neural network is implicated in the pathology of polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility. Although many symptoms of PCOS relate most proximately to ovarian dysfunction, the central reproductive neuroendocrine system ultimately drives ovarian function through its regulation of anterior pituitary gonadotropin release. The typical cyclical changes in frequency of GnRH release are often absent in women with PCOS, resulting in a persistent high-frequency drive promoting gonadotropin changes (i.e., relatively high luteinizing hormone and relatively low follicle-stimulating hormone concentrations) that contribute to ovarian hyperandrogenemia and ovulatory dysfunction. However, the specific mechanisms underpinning GnRH neuron dysfunction in PCOS remain unclear. Here, we summarize several preclinical and clinical studies that explore the causes of aberrant GnRH secretion in PCOS and the role of disordered GnRH secretion in PCOS pathophysiology.