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Kisspeptin is an essential neuropeptide sitting at the apex of the hypothalamo-pituitary-gonadal (HPG) endocrine axis to regulate gonadotropin-releasing hormone (GnRH) neurons and downstream reproductive hormones. Kisspeptin neurons integrate feedback from sex steroids facilitating regulation of the menstrual cycle and mediate the effects of metabolic stressors on the reproductive axis. In this issue of the JCI, Torres and colleagues describe another pathway for kisspeptin signaling in astrocytes to influence GnRH neuronal output. Astrocytes had kisspeptin receptors that activated canonical intracellular signaling pathways to constrain the magnitude of kisspeptin-induced GnRH neuronal stimulation. Additionally, the appositions between kisspeptin and GnRH neurons were dynamic during the ovarian cycle, with astrocyte kisspeptin signaling proposed as a putative modulator of this neuroplasticity. Importantly, astrocyte kisspeptin signaling also mediated susceptibility to metabolic stressors and the development of obesity-induced hypogonadism, underscoring the physiological and pathological importance of this pathway and revealing the importance of nonneuronal signaling in reproductive health., Kisspeptin regulates GnRH neurons in the hypothalamus Kisspeptin is essential for reproductive health; inactivating variants in genes encoding for kisspeptin or its receptor result in hypogonadotropic hypogonadism and a failure [...]

Introduction: Polycystic ovarian syndrome (PCOS) is the commonest endocrine condition affecting reproductive age women. Many biomarkers may aid assessment and management, however evidence is limited on their utility in clinical practice. We conducted a review of systematic reviews to identify the most useful biomarkers in the clinical management of PCOS. Methods: We searched MEDLINE, EMBASE, CENTRAL and HTA until August 2023 for reviews evaluating biomarkers in PCOS women compared to healthy controls. Methodological quality was assessed using the AMSTAR2 tool. We reported pooled evidence for each biomarker with 95% confidence intervals from the most recent, up‐to‐date, and best quality review. Results: From 3360 citations, we included 75 systematic reviews (88 biomarkers, 191,792 women). Most reviews (50/75, 67%) were moderate quality, but reported high heterogeneity (66/75, 88%). We identified 63 abnormal biomarkers in women with PCOS versus healthy controls. Of these, 22 core biomarkers could help evaluate the multisystemic impact of PCOS and inform patient management and surveillance: dehydroepiandrosterone, prolactin, sex hormone‐binding globulin, total and free testosterone, anti‐Mullerian hormone, systolic and diastolic blood pressure, c‐reactive protein, fibrinogen, oral glucose tolerance test, homoeostatic model assessment‐insulin resistance index, fasting insulin, total cholesterol, triglycerides, lipoprotein(a), HDL, LDL, non‐HDL‐cholesterol, ferritin, iron, and 25‐hydroxy‐vitamin D. Conclusion: We identified 22 core biomarkers assessing the multisystemic impact of PCOS and inform its clinical management. Future research is required to establish validated healthcare pathways. [ABSTRACT FROM AUTHOR]

The neuropeptide kisspeptin and its cognate receptor have been extensively studied in reproductive physiology, with diverse and well‐established functions, including as an upstream regulator of pubertal onset, reproductive hormone secretion, and sexual behavior. Besides classical reproduction, both kisspeptin and its receptor are extensively expressed in bone‐resorbing osteoclasts and bone‐forming osteoblasts, which putatively permits direct bone effects. Accordingly, this sets the scene for recent compelling findings derived from in vitro experiments through to in vivo and clinical studies revealing prominent regulatory interactions for kisspeptin signaling in bone metabolism, as well as certain oncological aspects of bone metabolism. Herein, we comprehensively examine the experimental evidence obtained to date supporting the interaction between kisspeptin and bone. A comprehensive understanding of this emerging facet of kisspeptin biology is fundamental to exploiting the future therapeutic potential of kisspeptin‐based medicines as a novel strategy for treating bone‐related disorders. [ABSTRACT FROM AUTHOR]

Functional hypothalamic amenorrhea (FHA) is one of the most common causes of secondary amenorrhea, resulting in anovulation and infertility, and is a low estrogen state that increases the risk of cardiovascular disease and impairs bone health. FHA is characterized by acquired suppression of physiological pulsatile gonadotropin‐releasing hormone (GnRH) release by the hypothalamus in the absence of an identifiable structural cause, resulting in a functional hypogonadotropic hypogonadism. FHA results from either decreased energy intake and/or excessive exercise, leading to low energy availability and weight loss—often in combination with psychological stress on top of a background of genetic susceptibility. The hypothalamic neuropeptide kisspeptin is a key component of the GnRH pulse generator, tightly regulating pulsatile GnRH secretion and the downstream reproductive axis. Here, we review the physiological regulation of pulsatile GnRH secretion by hypothalamic kisspeptin neurons and how their activity is modulated by signals of energy status to affect reproductive function. We explore endocrine factors contributing to the suppression of GnRH pulsatility in the pathophysiology of FHA and how hypothalamic kisspeptin neurons likely represent a final common pathway through which these factors affect GnRH pulse generation. Finally, we discuss the therapeutic potential of kisspeptin as a novel treatment for women with FHA. [ABSTRACT FROM AUTHOR]

Menopausal hormone therapy (MHT) is an effective treatment for menopause‐related symptoms. Menopause management guidelines recommend a personalized approach to menopause care, including MHT use. Decision‐making around menopause care is a complex, iterative process influenced by multiple factors framed by perspectives from both women and healthcare providers (HCPs). This narrative review aims to summarize evidence around factors affecting decision‐making regarding menopause‐related care. For HCPs, the provision of individualized risk estimates is challenging in practice given the number of potential benefits and risks to consider, and the complexity of the data available, especially within time‐limited consultations. Women seeking menopause care have the difficult task of making sense of the benefit versus risk profiles to make choices in line with their decisional needs influenced by sociocultural/economic, educational, demographic, and personal characteristics. The press, social media, and influential celebrities also impact the perception of menopause and decision‐making around it. Understanding these factors can lead to improved participation in shared decision‐making, satisfaction with the decision and decision‐making process, adherence to treatment, reduced decisional regret, efficient use of resources, and ultimately long‐term satisfaction with care. [ABSTRACT FROM AUTHOR]

BACKGROUND. Kisspeptin is a key regulator of hypothalamic gonadotropin-releasing hormone (GnRH) neurons and is essential for reproductive health. A specific kisspeptin receptor (KISS1R) agonist could significantly expand the potential clinical utility of therapeutics targeting the kisspeptin pathway. Herein, we investigate the effects of a KISS1R agonist, MVT-602, in healthy women and in women with reproductive disorders. METHODS. We conducted in vivo and in vitro studies to characterize the action of MVT-602 in comparison with native kisspeptin-54 (KP54). We determined the pharmacokinetic and pharmacodynamic properties of MVT-602 (doses 0.01 and 0.03 nmol/kg) versus KP54 (9.6 nmol/kg) in the follicular phase of healthy women (n = 9), and in women with polycystic ovary syndrome (PCOS; n = 6) or hypothalamic amenorrhea (HA; n = 6). Further, we investigated their effects on KISS1R-mediated inositol monophosphate ([IP.sub.1]) and [Ca.sup.2+] signaling in cell lines and on action potential firing of GnRH neurons in brain slices. RESULTS. In healthy women, the amplitude of luteinizing hormone (LH) rise was similar to that after KP54, but peaked later (21.4 vs. 4.7 hours; P = 0.0002), with correspondingly increased AUC of LH exposure (169.0 vs. 38.5 IU-h/L; P = 0.0058). LH increases following MVT-602 were similar in PCOS and healthy women, but advanced in HA (P = 0.004). In keeping with the clinical data, MVT-602 induced more potent signaling of KISS1R-mediated [IP.sub.1] accumulation and a longer duration of GnRH neuron firing than KP54 (115 vs. 55 minutes; P = 0.0012). CONCLUSION. Taken together, these clinical and mechanistic data identify MVT-602 as having considerable therapeutic potential for the treatment of female reproductive disorders. TRIAL REGISTRATION. International Standard Randomised Controlled Trial Number (ISRCTN) Registry, ISRCTN21681316. FUNDING. National Institute for Health Research and NIH., Introduction Kisspeptin is recognized to play a pivotal role in the regulation of reproductive hormone secretion following 2 landmark reports in 2003, demonstrating that decreased signaling of its G protein-coupled [...]

BACKGROUND. Hypoactive sexual desire disorder (HSDD) is characterized by a persistent deficiency of sexual fantasies and desire for sexual activity, causing marked distress and interpersonal difficulty. It is the most prevalent female sexual health problem globally, affecting approximately 10% of women, but has limited treatment options. Melanocortin 4 receptor (MC4R) agonists have emerged as a promising therapy for women with HSDD, through unknown mechanisms. Studying the pathways involved is crucial for our understanding of normal and abnormal sexual behavior. METHODS. Using psychometric, functional neuroimaging, and hormonal analyses, we conducted a randomized, double-blinded, placebo-controlled, crossover clinical study to assess the effects of MC4R agonism compared with placebo on sexual brain processing in 31 premenopausal heterosexual women with HSDD. RESULTS. MC4R agonism significantly increased sexual desire for up to 24 hours after administration compared with placebo. During functional neuroimaging, MC4R agonism enhanced cerebellar and supplementary motor area activity and deactivated the secondary somatosensory cortex, specifically in response to visual erotic stimuli, compared with placebo. In addition, MC4R agonism enhanced functional connectivity between the amygdala and the insula during visual erotic stimuli compared with placebo. CONCLUSION. These data suggest that MC4R agonism enhanced sexual brain processing by reducing self-consciousness, increasing sexual imagery, and sensitizing women with HSDD to erotic stimuli. These findings provide mechanistic insight into the action of MC4R agonism in sexual behavior and are relevant to the ongoing development of HSDD therapies and MC4R agonist development more widely. TRIAL REGISTRATION. ClinicalTrials.gov NCT04179734. FUNDING. This is an investigator-sponsored study funded by AMAG Pharmaceuticals Inc., the Medical Research Council (MRC) (MR/T006242/1), and the National Institute for Health Research (NIHR) (CS-2018-18-ST2-002 and RP-2014-05-001)., Introduction Sexual arousal and desire are fundamental physiological processes in humans and are designed to drive sexual activity and ultimately reproduction at a population level. The presence of sexual arousal [...]

The signals maintaining quiescence of the reproductive endocrine axis during childhood before its reawakening at puberty had been enigmatic. Studies in patients with abnormal puberty have illuminated the identity of the signals; kisspeptin has emerged as a major stimulator of puberty, and makorin RING finger protein 3 (MKRN3) as an inhibitory signal that prevents premature initiation of puberty. In this issue of the JCI, Abreu et al. investigated the mechanism by which MKRN3 regulates pubertal onset. The authors found that a reduction in MKRN3 alleviated the constraint on kisspeptin-expressing neurons to allow pubertal initiation, a phenomenon observed across species, including nonhuman primates. Further, the ubiquitinase activity of MKRN3 required its RING finger domain, in order to repress the promoter activity of genes encoding kisspeptin and neurokinin B. These data advance our understanding of the regulation of kisspeptin-expressing neurons by MKRN3 to initiate puberty., What initiates puberty? Activation of the hypothalamic-pituitary-gonadal (HPG) axis to initiate puberty and acquire competence for adult reproductive health is a fundamental physiological process. Conspicuously, the timing of the pubertal [...]

Obesity-related hypogonadotropic hypogonadism is a well-characterized condition in men (termed male obesity-related secondary hypogonadism; MOSH); however, an equivalent condition has not been as clearly described in women. The prevalence of polycystic ovary syndrome (PCOS) is known to increase with obesity, but PCOS is more typically characterized by increased gonadotropin-releasing hormone (GnRH) (and by proxy luteinizing hormone; LH) pulsatility, rather than by the reduced gonadotropin levels observed in MOSH. Notably, LH levels and LH pulse amplitude are reduced with obesity, both in women with and without PCOS, suggesting that an obesity-related secondary hypogonadism may also exist in women akin to MOSH in men. Herein, we examine the evidence for the existence of a putative non-PCOS "female obesity-related secondary hypogonadism" (FOSH). We précis possible underlying mechanisms for the occurrence of hypogonadism in this context and consider how such mechanisms differ from MOSH in men, and from PCOS in women without obesity. In this review, we consider relevant etiological factors that are altered in obesity and that could impact on GnRH pulsatility to ascertain whether they could contribute to obesity-related secondary hypogonadism including: anti-Müllerian hormone, androgen, insulin, fatty acid, adiponectin, and leptin. More precise phenotyping of hypogonadism in women with obesity could provide further validation for non-PCOS FOSH and preface the ability to define/investigate such a condition. [ABSTRACT FROM AUTHOR]

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease, has become a silent worldwide pandemic. The incidence of NAFLD correlates with the rise in obesity, type 2 diabetes, and metabolic syndrome. A hallmark feature of NAFLD is excessive hepatic fat accumulation or steatosis, due to dysregulated hepatic fat metabolism, which can progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Currently, there are no approved pharmacotherapies to treat this disease. Here, we have found that activation of the kisspeptin 1 receptor (KISS1R) signaling pathway has therapeutic effects in NAFLD. Using high-fat diet-fed mice, we demonstrated that a deletion of hepatic Kiss1r exacerbated hepatic steatosis. In contrast, enhanced stimulation of KISS1R protected against steatosis in wild-type C57BL/6J mice and decreased fibrosis using a diet-induced mouse model of NASH. Mechanistically, we found that hepatic KISS1R signaling activates the master energy regulator, AMPK, to thereby decrease lipogenesis and progression to NASH. In patients with NAFLD and in high-fat diet-fed mice, hepatic KISS1/KISS1R expression and plasma kisspeptin levels were elevated, suggesting a compensatory mechanism to reduce triglyceride synthesis. These findings establish KISS1R as a therapeutic target to treat NASH., Introduction The liver is the principal organ involved in lipid metabolism. Dyslipidemia leads to metabolic disorders such as nonalcoholic fatty liver disease (NAFLD), which has become an increasing global public [...]

Kisspeptin (KP) and neurokinin B (NKB) are neuropeptides that govern the reproductive endocrine axis through regulating hypothalamic gonadotropin-releasing hormone (GnRH) neuronal activity and pulsatile GnRH secretion. Their critical role in reproductive health was first identified after inactivating variants in genes encoding for KP or NKB signaling were shown to result in congenital hypogonadotropic hypogonadism and a failure of pubertal development. Over the past 2 decades since their discovery, a wealth of evidence from both basic and translational research has laid the foundation for potential therapeutic applications. Beyond KP's function in the hypothalamus, it is also expressed in the placenta, liver, pancreas, adipose tissue, bone, and limbic regions, giving rise to several avenues of research for use in the diagnosis and treatment of pregnancy, metabolic, liver, bone, and behavioral disorders. The role played by NKB in stimulating the hypothalamic thermoregulatory center to mediate menopausal hot flashes has led to the development of medications that antagonize its action as a novel nonsteroidal therapeutic agent for this indication. Furthermore, the ability of NKB antagonism to partially suppress (but not abolish) the reproductive endocrine axis has supported its potential use for the treatment of various reproductive disorders including polycystic ovary syndrome, uterine fibroids, and endometriosis. This review will provide a comprehensive up-to-date overview of the preclinical and clinical data that have paved the way for the development of diagnostic and therapeutic applications of KP and NKB. [ABSTRACT FROM AUTHOR]