kiss1-protein--human and Infertility

Inflammatory diseases attenuate reproductive functions in humans and domestic animals. Lipopolysaccharide (LPS), an endotoxin released by bacteria, is known to disrupt female reproductive functions in various inflammatory diseases. LPS administration has been used to elucidate the impact of pathophysiological activation of the immune system on reproduction. Hypothalamic kisspeptin neurons are the master regulators of mammalian reproduction, mediating direct stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) release and consequent release of gonadotropins, such as luteinizing hormone (LH) and follicle-stimulating hormone from the pituitary. The discovery of kisspeptin neurons in the mammalian hypothalamus has drastically advanced our understanding of how inflammatory stress causes reproductive dysfunction in both humans and domestic animals. Inflammation-induced ovarian dysfunction could be caused, at least partly, by aberrant GnRH and LH secretion, which is regulated by kisspeptin signaling. In this review, we focus on the effects of LPS on hypothalamic kisspeptin neurons to outline the impact of inflammatory stress on neuroendocrine regulation of mammalian reproductive systems. First, we summarize the attenuation of female reproduction by LPS during inflammation and the effects of LPS on ovarian and pituitary function. Second, we outline the inhibitory effects of LPS on pulsatile- and surge-mode GnRH/LH release. Third, we discuss the LPS-responsive hypothalamic-pituitary-adrenal axis and hypothalamic neural systems in terms of the cytokine-mediated pathway and the possible direct action of LPS via its hypothalamic receptors. This article describes the impact of LPS on hypothalamic kisspeptin neurons and the possible mechanisms underlying LPS-mediated disruption of LH pulses/surge via kisspeptin neurons.

Topics: Animals; Animals, Domestic; Female; Gonadotropin-Releasing Hormone; Humans; Hypothalamo-Hypophyseal System; Hypothalamus; Infertility; Kisspeptins; Lipopolysaccharides; Luteinizing Hormone; Mammals; Neurons; Pituitary-Adrenal System

A highly accurate serum marker for predicting viable pregnancy needs to be developed. Recent studies have demonstrated that kisspeptin is a potential biomarker for this purpose.. This systematic review evaluated the available data in the literature on the role of kisspeptin as a miscarriage biomarker. A literature search was conducted in the PubMed/Medline, Embase, Web of Science, and Scopus databases using the following keywords: (kisspeptin) AND (miscarriage OR pregnancy loss OR spontaneous abortion OR reproductive failure).. Seven case-control studies were selected for the systematic review. The included papers described the potential role of kisspeptin as a putative biomarker of pregnancy loss. Furthermore, two studies reported that changes in kisspeptin levels may be associated with unexplained infertility and low rates of embryo implantation in women undergoing assisted reproductive technology.. Kisspeptin might be used as a potential biomarker of pregnancy viability in the near future. However, studies with better evidence are needed to establish the applicability of kisspeptin as a diagnostic and prognostic tool.

Topics: Abortion, Spontaneous; Biomarkers; Female; Fertilization in Vitro; Humans; Infertility; Kisspeptins; Live Birth; Pregnancy; Pregnancy Rate; Reproductive Techniques, Assisted

To summary the clinical features of premenopausal women with functioning gonadotroph adenomas (FGAs) and preliminarily explore their molecular characterization.. 12 premenopausal females with FGAs in our center were retrospectively analyzed. Previously reported cases were also summarized. The patients were clinically divided into FSH- or LH-predominant types according to their preoperative serum FSH/LH ratio. The expressions of related genes in the tumor tissues of female FGAs, non-functioning gonadotroph adenomas (NFGAs), and silent corticotropin adenomas were evaluated by RT-qPCR.. Of all the 12 patients with FGAs from our center, 11 (91.7%) were diagnosed as FSH-predominant type, and they all had menstrual disorders, including 9 with spontaneous ovarian hyperstimulation syndrome (sOHSS). Their hormonal profiles showed non-suppressed FSH (12.45 ± 7.34 IU/L) with hyperestrogenemia [median estradiol level 1353.0 pg/mL (636.0, 3535.0)]. The other patient (8.3%) with LH-predominant type mainly manifested with infertility and sustained elevated serum LH without FSH or estradiol increasing. 65 premenopausal FGAs patients were systematic reviewed. 60 patients (92.3%) were FSH-predominant type, including 86.7% presented with menstrual disorders, 16.7% reported infertility, and 98.2% (55/56) showed sOHSS. No sOHSS or hyperestrogenemia were found in the 5 patients (7.7%) with LH-predominant type. Pituitary imaging data revealed macroadenomas and microadenomas accounted for 89.2% and 10.8%, respectively. Of 63 patients (96.9%) who underwent pituitary adenoma resection, 77.8% had complete tumor resection and no recurrence at the last follow-up. The relative expressions of KISS1 mRNA were significantly higher in FGA group than in NFGA group (p = 0.018), and significantly positively correlated with the preoperative serum estradiol levels (p = 0.004).. Different clinical features were observed in premenopausal women with FGAs of FSH- or LH-predominant types. The elevated KISS1 expression in tumor tissues might involve in the secretion function of FGAs.

Topics: Adenoma; Estradiol; Female; Follicle Stimulating Hormone; Gonadotrophs; Humans; Infertility; Kisspeptins; Luteinizing Hormone; Pituitary Neoplasms; Retrospective Studies

To briefly summarize what is known regarding hyperprolactinemia and prolactin-secreting tumors, and review recent findings.. Prolactin was previously thought to inhibit secretion of gonadotropin-releasing hormone (GnRH) by directly inhibiting the firing of GnRH neurons, resulting in hypogonadotropic hypogonadism and infertility. However, kisspeptin has recently been implicated as the mediator of hyperprolactinemia-induced infertility, by acting upstream of the GnRH neurons as an integrator of endocrine signals.Macroprolactin is generally considered to be inactive and clinically insignificant, but new studies have suggested that patients with macroprolactinemia may have reproductive manifestations as well as sexual dysfunction.Several mutations and polymorphisms in the prolactin receptor have been described, which could describe a genetic cause for prolactinomas and characterize cases of isolated familial hyperprolactinemia.Kisspeptin and tyrosine kinase inhibitors have emerged as potential new therapeutic targets for the treatment of hyperprolactinemia and dopamine-resistant prolactinomas.. Molecular studies are shedding light on the pathophysiology of hyperprolactinemia and the effects of excess prolactin production on the reproductive system. Similarly, genetic studies have begun to reveal how differences in prolactin receptor function may account for some of the previously 'idiopathic' cases of hyperprolactinemia and bring to light new causes of prolactinomas. Further elucidation of the transcriptional pathways affected by these genetic changes may help to create new therapeutic targets.

Topics: Animals; Female; Genetic Variation; Genomics; Gonadotropin-Releasing Hormone; Humans; Hyperprolactinemia; Infertility; Kisspeptins; Male; Mice; Mice, Transgenic; Neurons; Prolactin; Protein-Tyrosine Kinases; Receptors, Prolactin; Reproduction

Several kinds of stress suppress the hypothalamic-pituitary-gonadal (HPG) axis and reproductive behavior in humans and animals. These changes can eventually cause diseases and disorders, such as amenorrhea and infertility. In previous studies, it has been shown that stress-related factors, e.g., corticotropin-releasing hormone, cortisol, and pro-inflammatory cytokines, promote the stress-induced suppression of the HPG axis. However, these mechanisms are not sufficient to explain how stress suppresses HPG axis activity, and it has been suggested that some other factors might also be involved. In the early 21st century, novel neuroendocrine peptides, kisspeptin and gonadotropin inhibitory hormone (GnIH)/RFamide-related peptide 3 (RFRP-3), which directly regulate GnRH/gonadotropin synthesis and secretion, were newly discovered. Growing evidence indicates that kisspeptin and GnIH/RFRP-3 play pivotal roles in the stress-induced disruption of the HPG axis and reproductive behavior in addition to their physiological functions. This review summarizes what is currently known about the roles of kisspeptin and GnIH/RFRP-3 in stress-induced reproductive disorders.

Topics: Animals; Gonadotropins; Humans; Infertility; Kisspeptins; Neuropeptides; Stress, Psychological

Infertility affects one in six of the population and increasingly couples require treatment with assisted reproductive techniques. In vitro fertilization (IVF) treatment is most commonly conducted using exogenous FSH to induce follicular growth and human chorionic gonadotropin (hCG) to induce final oocyte maturation. However, hCG may cause the potentially life-threatening iatrogenic complication "ovarian hyperstimulation syndrome" (OHSS), which can cause considerable morbidity and, rarely, even mortality in otherwise healthy women. The use of GnRH agonists (GnRHas) has been pioneered during the last two decades to provide a safer option to induce final oocyte maturation. More recently, the neuropeptide kisspeptin, a hypothalamic regulator of GnRH release, has been investigated as a novel inductor of oocyte maturation. The hormonal stimulus used to induce oocyte maturation has a major impact on the success (retrieval of oocytes and chance of implantation) and safety (risk of OHSS) of IVF treatment. This review aims to appraise experimental and clinical data of hormonal approaches used to induce final oocyte maturation by hCG, GnRHa, both GnRHa and hCG administered in combination, recombinant LH, or kisspeptin. We also examine evidence for the timing of administration of the inductor of final oocyte maturation in relationship to parameters of follicular growth and the subsequent interval to oocyte retrieval. In summary, we review data on the efficacy and safety of the major hormonal approaches used to induce final oocyte maturation in clinical practice, as well as some novel approaches that may offer fresh alternatives in future.

Topics: Chorionic Gonadotropin; Fertilization in Vitro; Humans; In Vitro Oocyte Maturation Techniques; Infertility; Kisspeptins; Luteinizing Hormone; Oocyte Retrieval; Oocytes

Kisspeptin is involved in the control of human reproduction bridging the gap between the sex steroid levels and feedback mechanisms that control the gonadotropin releasing hormone (GnRH) secretion; however, studies considering this peptide and infertility are limited. We conducted a review and critical assessment of available evidence considering kisspeptin structure, physiology, function in puberty and reproduction, its role in assisted reproduction treatments, kisspeptin dosage and the impact on KISS1 and GPR54 genes. Literature searches were conducted in PubMed using keywords related to: (i) kisspeptin or receptors, kisspeptin-1 (ii) reproduction or infertility or fertility (iii) gene and (iv) dosage or measurement or quantification or serum level, in human. Kisspeptin is a product of KISS1 gene that binds to a G-protein-coupled receptor (GPR54/KISS1R) stimulating the release of GnRH by hypothalamic neurons, leading to secretion of pituitary gonadotropins (LH and FSH) and sexual steroids, which in turn will act in the gonads to produce the gametes. Kisspeptin is being recognized as a crucial regulator of the onset of puberty, the regulation of sex hormone mediated secretion of gonadotropins, and the control of fertility. Inactivating and activating mutations in both KISS1 or GPR54 genes were associated with hypogonadotropic hypogonadism and precocious puberty. Despite this, studies considering kisspeptin and infertility are scarce. The understanding of the role of kisspeptin may lead to its use as a biomarker in infertility treatments and use in controlled ovarian hyperstimulation.

Topics: Fertilization in Vitro; Genetic Variation; Genitalia; Gonadotropins; Humans; Infertility; Kisspeptins; Neurons; Receptors, Kisspeptin-1; Sexual Maturation

Optimal fertility in humans and animals relies on the availability of sufficient metabolic fuels, information about which is communicated to the brain via levels of the hormones leptin and insulin. The circadian clock system is also critical; this input is especially evident in the precise timing of the female-specific surge of GnRH and LH secretion that triggers ovulation the next day. Chronodisruption and metabolic imbalance can both impair reproductive activity, and these two disruptions exacerbate each other, such that they often occur simultaneously. Kisspeptin neurons located in the anteroventral periventricular nucleus of the hypothalamus are able to integrate both circadian and metabolic afferent inputs and use this information to modulate the timing and magnitude of the preovulatory GnRH/LH surge. In an environment in which exposure to high caloric diets and chronodisruptors such as artificial night lighting, shift work, and transmeridian travel have become the norm, the implications of these factors for couples struggling to conceive deserve closer attention and more public education.

Topics: Animals; Circadian Rhythm; Fertility; Gonadotropin-Releasing Hormone; Humans; Hypothalamus, Anterior; Infertility; Insulin; Kisspeptins; Leptin; Lighting; Luteinizing Hormone; Neurons; Ovulation; Reproduction; Shift Work Schedule; Travel

Gonadotropin-releasing hormone (GnRH) plays an important role in the process of reproduction. Studies have shown that a family of peptides Kisspeptin can act on GnRH-related neurons, stimulating the secretion of GnRH, and activating the hypothalamic-pituitary-gonadal axis. Both animal experiments and clinical studies have shown that exogenous administration of Kisspeptin is able to induce physiological GnRH release in healthy individuals and those with endocrine-disorders, which brings great hope for treatment of reproductive endocrine diseases. The effect of Kisspeptin is similar to the physiological process in induction of ovulation and ovum maturation, leading to high security and efficiency for women receiving

Topics: Animals; Endocrinology; Female; Gonadotropin-Releasing Hormone; Humans; Infertility; Kisspeptins; Pregnancy

Over the last 10 years, kisspeptins--peptide products of varying lengths encoded by the KISS1 gene--have been found to be key regulators of normal reproductive function throughout life in animals and humans. By activating the kisspeptin receptor [previously known as orphan G protein-coupled receptor 54 (GPR54)], they elicit an effect on the central gonadotropin-releasing hormone neurons. Administration of kisspeptin by either the subcutaneous or intravenous route potently stimulates endogenous gonadotropin hormone release in healthy men and women as well as in animals. Kisspeptin also stimulates endogenous release of gonadotropins in subfertile as well as healthy volunteers, and therefore it has potential as a novel therapeutic agent in reproductive disorders. Further human studies have shown that chronic, high-dose administration of kisspeptin causes desensitisation with rapid subsequent suppression of the hypothalamic-pituitary-gonadal axis, and therefore high-dose long-acting analogues may have a clinical role in treating sex hormone-dependent malignancies. By further elucidating the intricacies and mechanisms of the kisspeptin signalling system, and the tissues it acts on during different phases of the reproductive timeline (including during puberty, fertility, pregnancy and menopause), pharmacologic analogues could become clinically useful.

Topics: Animals; Female; Gonadotropin-Releasing Hormone; Humans; Hypothalamus; Infertility; Kisspeptins; Luteinizing Hormone; Male; Neurons; Pituitary Gland; Pregnancy; Pregnancy Complications; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Reproductive Physiological Phenomena; Sexual Maturation

Changes in metabolic status gate reproductive activity by still incompletely deciphered mechanisms. Many neuropeptides have been shown to be involved in restraining hypothalamic gonadotropin releasing hormone (GnRH) release under conditions of negative energy balance. Broadly, on the basis of their effect on feeding, these can be grouped as orexigenic and anorexigenic neuropeptides. Reciprocally correlated, in response to changes in systemic concentrations of metabolic hormones, the secretion of orexigenic neuropeptides increases while that of anorexigenic neuropeptides decreases during conditions of food restriction. Recently, kisspeptin signaling in hypothalamus has appeared as a pivotal regulator of the GnRH pulse generator. Kisspeptin apparently does not affect feeding, but in light of accumulating data, it has emerged as one of the major conduits in relaying body metabolic status information to GnRH neurons. The present review examines such data obtained from rodent and primate models, which suggest kisspeptin-Kiss1r signaling as a possible pathway providing a link between metabolism and reproduction.

Topics: Animals; Energy Metabolism; Female; Food Deprivation; Gonadotropin-Releasing Hormone; Humans; Hypothalamus; Infertility; Kisspeptins; Lactation; Male; Neurons; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction

Studies of the actions of kisspeptin in human subjects have examined the effects of different kisspeptin isoforms, doses, and routes of administration on LH secretion, a surrogate measure of GnRH release. These studies, in addition to detailing how these different variables affect LH secretion in response to kisspeptin, have produced new insights into kisspeptin physiology: (1) Brief exposure to kisspeptin results in sustained GnRH release lasting ~17 min in men. (2) Women in different phases of the menstrual cycle have differences in their response to kisspeptin, suggesting that endogenous kisspeptin secretion and GnRH neuronal responsiveness vary in response to the changing sex-steroid environment across the menstrual cycle. (3) Kisspeptin resets the GnRH pulse generator in men, but does not appear to do so in women. (4) Continuous exposure to kisspeptin results in desensitization to kisspeptin, and thus kisspeptin has the potential to either stimulate or suppress reproductive endocrine activity depending on the mode of administration. These findings pave the way for future studies using kisspeptin as a physiologic, diagnostic, and therapeutic tool in both healthy adults and in patients with reproductive disorders.

Topics: Adult; Female; Gonadotropin-Releasing Hormone; Humans; Infertility; Kisspeptins; Luteinizing Hormone; Male; Menstrual Cycle; Neurons; Sex Characteristics

Kisspeptin is now known to be an important regulator of the hypothalamic--pituitary-gonadal axis and is the target of a range of regulators, such as steroid hormone feedback, nutritional and metabolic regulation. Kisspeptin binds to its cognate receptor, KISS1R (also called GPR54), on GnRH neurons and stimulates their activity, which in turn provides an obligatory signal for GnRH secretion-thus gating down-stream events supporting reproduction. The development of peripherally active kisspeptin antagonists could offer a unique therapeutic agent for treating hormone-dependent disorders of reproduction, including precocious puberty, endometriosis, and metastatic prostate cancer. The following chapter discusses the advances made in the search for both peptide and small molecule kisspeptin antagonists and their use in delineating the role of kisspeptin within the reproductive system. To date, four peptide antagonists and one small molecule antagonist have been designed.

Topics: Animals; Endometriosis; Female; Gonadotropin-Releasing Hormone; Humans; Infertility; Kisspeptins; Male; Neurons; Prostatic Neoplasms; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction

The hypothalamic hormone GnRH has traditionally been viewed as a central driver of the hypothalamic-pituitary-gonadal axis. Pulsatile GnRH release is required for pulsatile gonadotropin secretion, which then modulates gonadal steroid feedback and brings about full fertility in the adult. Pathways governing GnRH ontogeny and physiology have been discovered by studying humans with disorders of GnRH secretion. In this chapter, the human genetics of the kisspeptin signaling pathway in patients with diverse reproductive phenotypes will be explored. The discovery of defects in the kisspeptin system in several reproductive disorders has shed light on the mechanisms involved in regulating GnRH secretion, revealing the critical role played by the kisspeptin signaling pathway in pubertal initiation and reproductive function.

Topics: Adult; Female; Fertility; Humans; Hypothalamo-Hypophyseal System; Infertility; Kisspeptins; Male; Signal Transduction

Sex steroid hormones, most notably estradiol, play a pivotal role in the sex-specific organization and function of the kisspeptin system. Endocrine--disrupting compounds are anthropogenic or naturally occurring compounds that interact with steroid hormone signaling. Thus, these compounds have the potential to disrupt the sexually dimorphic ontogeny and function of kisspeptin signaling pathways, resulting in adverse effects on neuroendocrine physiology. This chapter reviews the small but growing body of evidence for endocrine disruption of the kisspeptin system by the exogenous estrogenic compounds bisphenol A, polychlorinated biphenyl mixtures, and the phytoestrogen genistein. Disruption is region, sex, and compound specific, and associated with shifts in the timing of pubertal onset, irregular estrous cycles, and altered sociosexual behavior. These effects highlight that disruption of kisspeptin signaling pathways could have wide ranging effects across multiple organ systems, and potentially underlies a suite of adverse human health trends including precocious female puberty, idiopathic infertility, and metabolic syndrome.

Topics: Animals; Benzhydryl Compounds; Estradiol; Female; Genistein; Humans; Infertility; Kisspeptins; Menstrual Cycle; Metabolic Syndrome; Neurosecretory Systems; Phenols; Phytoestrogens; Puberty, Precocious; Sexual Behavior; Signal Transduction

Kisspeptin is a 54-amino acid peptide which is encoded by the KiSS-1 gene and activates the G protein-coupled receptor GPR54. Evidence suggests that this system is a key regulator of mammalian and human reproduction. Animal studies have shown that GPR54-deficient mice have abnormal sexual development. Central and peripheral administration of kisspeptin stimulates the hypothalamic-pituitary-gonadal (HPG) axis whilst pre-administration of a gonadotrophin releasing hormone (GnRH) antagonist abolishes this effect. In humans, inactivating GPR54 mutations cause normosmic hypogonadotrophic hypogonadism whilst activation of GPR54 signalling is associated with premature puberty. In healthy human volunteers, the acute intravenous administration of kisspeptin potently increases plasma luteinising hormone (LH) levels and significantly increases plasma follicle stimulating hormone (FSH) and testosterone without side effects in both males and in females particularly in the preovulatatory phase of the menstrual cycle. In infertility due to hypothalamic amenorrhoea acute administration of kisspeptin results in stimulation of reproductive hormones. The kisspeptin/GPR54 system therefore appears to play an important role in the regulation of reproduction in humans. Hence kisspeptin has potential as a novel tool for the manipulation of the HPG axis and treatment of infertility in humans. This review discusses the evidence highlighting kisspeptin's key role in human reproduction.

Topics: Amenorrhea; Amino Acid Sequence; Animals; Female; Humans; Hypogonadism; Infertility; Kisspeptins; Male; Molecular Sequence Data; Mutation; Puberty; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction

The kisspeptins are a family of peptide hormones, which in recent years have been shown to play a critical role in the regulation of the hypothalamic-pituitary-gonadal axis, thus in turn influencing fertility and reproduction. This review examines the physiological role of kisspeptin and the kisspeptin receptor in the control of gonadotrophin and gonadal steroid hormone secretion and the implications of these findings with respect to fertility. In addition, the potential therapeutic use of kisspeptin in the treatment of reproductive disorders will be examined.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Feedback, Physiological; Fertility; Gonadotropin-Releasing Hormone; Gonadotropins; Gonads; Growth Hormone; Humans; Hypothalamo-Hypophyseal System; Hypothalamus; Infertility; Kisspeptins; Neurons; Neuropeptides; Nutritional Status; Pituitary Gland; Pituitary-Adrenal System; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Seasons; Signal Transduction; Steroids; Tissue Distribution; Tumor Suppressor Proteins

The occurrence of reproductive infertility has become an increasing concern in the developed world, particularly following the recent trend of attempts at pregnancy later in maternal life. Most existing therapies for infertility, such as clomiphene and gonadotropins, aim to manipulate the traditional components of the hypothalamic-pituitary-gonadal axis. Several secretagogues of gonadotropin-releasing hormone (GnRH) have been identified, including glutamate, neuropeptide tyrosine (NPY) and substance P; however, the broad array of action of these secretagogues in the CNS make them unsuitable as therapeutic targets. In the last 5 years, the Kisspeptin system has emerged as a critical regulator of reproduction and as a putative novel target of therapy for reproductive disorders. This review summarizes the relevant contemporary literature related to Kisspeptin, and assesses the potential applications of this group of peptides as a novel therapeutic target.

Topics: Animals; Female; Fertility; Fertility Agents; Humans; Hypothalamo-Hypophyseal System; Infertility; Kisspeptins; Luteinizing Hormone; Male; Menstrual Cycle; Placenta; Pregnancy; Proteins; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

The UK and international neuroendocrine community was deeply shocked and saddened the unbelievably premature death of Michael Harbuz in Bristol in 2006. Mick was a superb friend and colleague, and played a huge part in the development and activities of the British Neuroendocrine Group/British Society for Neuroendocrinology (BSN), serving as both Membership Secretary and Treasurer between 1999 and 2004. Mick was a leader in the field of neuroendocrine-immune interactions, and brought a great deal of charisma, humour and ability to meetings and conferences. He was also a passionate and committed supporter of the progress of young researchers and of their participation in neuroendocrine events. He recognised that today's postgraduate students and postdoctoral research fellows are tomorrow's neuroendocrine researchers, be it in academia, the health services or industry. To recognise Mick's great commitment to and enthusiasm for postgraduate education both in the University of Bristol and in the BSN, we decided to honour and remember him by instituting the 'Michael Harbuz Young Investigator Prize Lecture' to be delivered annually. Dr Waljit Dhillo from Imperial College London was the inaugural recipient of this award, and presented his lecture at the Annual Meeting of the BSN in Nottingham in September 2007, upon which this review is based. Recent evidence demonstrates that the neuropeptide kisspeptin and its receptor, GPR54, have a fundamental role in initiating the onset of puberty and are important in regulating reproductive function. This review discusses the evidence available from animals and humans demonstrating that kisspeptin potently stimulates the release of gonadotrophins by stimulating the release of gonadotrophin-releasing hormone and that a lack of kisspeptin or GPR54 results in reproductive failure.

Topics: Animals; Female; Gene Expression Regulation; Gonadal Steroid Hormones; Gonadotropin-Releasing Hormone; Humans; Hypothalamus; Infertility; Kisspeptins; Male; Mice; Mice, Knockout; Models, Biological; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Tumor Suppressor Proteins

Gonadotropin releasing hormone is the hypothalamic hormone that activates pituitary gonadotropin production and, ultimately, determines reproductive competence. This review will highlight advances in the basic biology of the gonadotropin releasing hormone neuron that give insight into disorders of pubertal development, and clinical studies with gonadotropin releasing hormone analogs in infertility and prostate cancer treatment.. Factors that control gonadotropin releasing hormone neuronal migration such as fibroblast growth factor receptor-1 and others that modulate secretion at puberty including kisspeptin/G-protein-coupled receptor 54 have been identified. Mutations in these pathways cause disorders during puberty. Clinical trials have defined the utility of gonadotropin releasing hormone agonists and antagonists for ovulation induction, and the effects of long-term administration for prostate cancer.. Research into the role of the fibroblast growth factor receptor-1 and kisspeptin/G-protein-coupled receptor 54 pathways in gonadotropin releasing hormone neuronal development may identify the molecular defects in idiopathic hypogonadotropic hypogonadism and refine our understanding of normal negative and positive feedback by sex steroids. Clarification of the advantages and disadvantages of gonadotropin releasing hormone analog use in ovulation induction may improve the cost and success of infertility treatment. Insight into long-term effects of gonadotropin releasing hormone analogs in prostate cancer may lead to directed therapies to combat these consequences. Together these studies outline effects of modulation of gonadotropin releasing hormone in normal and pathophysiologic states.

Topics: Endocrine Glands; Gonadotropin-Releasing Hormone; Humans; Hypothalamus; Infertility; Kisspeptins; Male; Prostatic Neoplasms; Receptors, G-Protein-Coupled; Signal Transduction; Tumor Suppressor Proteins

Leptin, a key hormone in energy homeostasis and neuroendocrine function, has a permissive role in initiating puberty and is crucial in the pathogenesis of reproductive dysfunction in several disease states of energy imbalance. KiSS1 neurons have recently been suggested to mediate leptin's effect on the reproductive system. New insights from recent animal studies and clinical trials are discussed.. Alterations in the expression profile of the KiSS1 gene and the kisspeptin receptor have been linked to reproductive dysfunction in leptin-deficient states. Neuroendocrine, including reproductive, dysfunction can be restored in humans and animals by leptin-replacement therapy. These insights have significantly advanced our understanding of hormonal systems needed to maintain normal reproduction. These data, if confirmed, also suggest a role for leptin as a novel therapeutic approach in several disease states.. Recent proof-of-concept studies involving leptin administration to humans underline the critical role of leptin not only in regulating energy homeostasis, but also in maintaining normal reproductive function. Leptin-replacement therapy is currently under intensive investigation as a potential novel therapeutic option for several conditions associated with reproductive dysfunction due to hypoleptinemia.

Topics: Amenorrhea; Animals; Anorexia Nervosa; Energy Metabolism; Female; Gonads; Humans; Hypothalamo-Hypophyseal System; Infertility; Kisspeptins; Leptin; Male; Menarche; Obesity; Polycystic Ovary Syndrome; Puberty; Reproduction; Sex Characteristics; Tumor Suppressor Proteins

Can serum kisspeptin levels 14 and 21 days after frozen-thawed embryo transfer predict the early pregnancy outcome of patients?. Prospective study, with 133 patients undergoing frozen-thawed embryo transfer. Patients were divided into non-pregnant group and pregnant group (including biochemical pregnancy, singleton pregnancy, miscarriage and twin groups).. Serum kisspeptin levels on day 21 were significantly higher than day 14 in singleton pregnancy, miscarriage and twin groups (all P < 0.0001), but not in the biochemical pregnancy group. Similarly, serum human chorionic gonadotrophin (HCG) levels were higher on day 21 compared with day 14 except for the biochemical pregnancy group. Compared with the twin group (296.9 pg/ml), the other four groups showed significantly higher serum kisspeptin levels on day 14 (non-pregnant 548.9, biochemical pregnancy 440.4, miscarriage 434.9, singleton pregnancy group 420.9 pg/ml, P < 0.01, P = 0.016, P = 0.034, P = 0.036, respectively). The miscarriage (762.2 pg/ml), singleton pregnancy (730.8 pg/ml) and twin groups (826.3 pg/ml) had significantly higher kisspeptin levels than the biochemical pregnancy group (397.3 pg/ml) on day 21 (P < 0.001, P < 0.01, P < 0.001, respectively). Serum kisspeptin levels on day 14 were negatively correlated with embryo implantation rate (P = 0.035, R. Serum kisspeptin levels on day 14 are negatively correlated with embryo implantation rate. Serum kisspeptin levels on day 21 have a poor predictive value of miscarriage.

Topics: Abortion, Spontaneous; Adult; Chorionic Gonadotropin; Cryopreservation; Embryo Implantation; Embryo Transfer; Female; Freezing; Humans; Infertility; Kisspeptins; Predictive Value of Tests; Pregnancy; Pregnancy Outcome; Pregnancy Rate; Time Factors; Young Adult

What are the in vivo and in vitro actions of kisspeptin-54 on the expression of genes involved in ovarian reproductive function, steroidogenesis and ovarian hyperstimulation syndrome (OHSS) in granulosa lutein (GL) cells when compared with traditional triggers of oocyte maturation?. The use of kisspeptin-54 as an oocyte maturation trigger augmented expression of genes involved in ovarian steroidogenesis in human GL cells including, FSH receptor (FSHR), LH/hCG receptor (LHCGR), steroid acute regulatory protein (STAR), aromatase, estrogen receptors alpha and beta (ESR1, ESR2), 3-beta-hydroxysteroid dehydrogenase type 2 (3BHSD2) and inhibin A (INHBA), when compared to traditional maturation triggers, but did not alter markers of OHSS.. hCG is the most widely used trigger of oocyte maturation, but is associated with an increased risk of OHSS. The use of GnRH agonists to trigger oocyte maturation is a safer alternative to hCG. More recently, kisspeptin-54 has emerged as a novel therapeutic option that safely triggers oocyte maturation even in women at high risk of OHSS. Kisspeptin indirectly stimulates gonadotropin secretion by acting on hypothalamic GnRH neurons. Kisspeptin and its receptor are also expressed in the human ovary, but there is limited data on the direct action of kisspeptin on the ovary.. Forty-eight women undergoing IVF treatment for infertility consented to kisspeptin-54 triggering and/or granulosa cell collection and were included in the study. Twelve women received hCG, 12 received GnRH agonist and 24 received kisspeptin-54 to trigger oocyte maturation. In the kisspeptin-54 group, 12 received one injection of kisseptin-54 (9.6 nmol/kg) and 12 received two injections of kisspeptin-54 at a 10 h interval (9.6 nmol/kg × 2).. Follicular fluid was aspirated and pooled from follicles during the retrieval of oocytes for IVF/ICSI. GL cells were isolated and either RNA extracted immediately or cultured in vitro ± kisspeptin or hCG.. GL cells from women who had received kisspeptin-54 had a 14-fold and 8-fold higher gene expression of FSHR and a 2-fold (ns) and 2.5-fold (P < 0.05) higher expression of LHCGR than GL cells from women who had received hCG or GnRH agonist, respectively. CYP19A1 expression was 3.6-fold (P < 0.05) and 4.5-fold (P < 0.05) higher, STAR expression was 3.4-fold (P < 0.01) and 1.8-fold (P < 0.05) higher, HSD3B2 expression was 7.5- (P < 0.01) and 2.5-fold higher (P < 0.05), INHBA was 2.5-fold (P < 0.01) and 2.5-fold (P < 0.01) higher in GL cells from women who had received kisspeptin-54 than hCG or GnRHa, respectively. ESR1 (P < 0.05) and ESR2 (P < 0.05) both showed 3-fold higher expression in cells from kisspeptin treated than GnRHa treated women. Markers of vascular permeability and oocyte growth factors were unchanged (VEGFA, SERPINF1, CDH5, amphiregulin, epiregulin). Gene expression of kisspeptin receptor was unchanged. Whereas treating GL cells in vitro with hCG induced steroidogenic gene expression, kisspeptin-54 had no significant direct effects on either OHSS genes or steroidogenic genes.. Most women in the study had PCOS, which may limit applicability to other patient groups. For the analysis of the in vitro effects of kisspeptin-54, it is important to note that GL cells had already been exposed in vivo to an alternate maturation trigger.. The profile of serum gonadotropins seen with kisspeptin administration compared to other triggers more closely resemble that of the natural cycle as compared with hCG. Thus, kisspeptin could potentially permit an ovarian environment augmented for steroidogenesis, in particular progesterone synthesis, which is required for embryo implantation.. Dr Owens is supported by an Imperial College London PhD Scholarship. Dr Abbara is supported by an National Institute of Health Research Academic Clinical Lectureship. The authors do not have any conflict of interest to declare.. ClinicalTrials.gov NCT01667406.

Topics: Adult; Cells, Cultured; Chorionic Gonadotropin; Female; Gene Expression; Gonadotropin-Releasing Hormone; Humans; In Vitro Oocyte Maturation Techniques; Infertility; Kisspeptins; Luteal Cells; Ovarian Hyperstimulation Syndrome; Ovulation Induction; Pregnancy; Receptors, Gonadotropin; Receptors, Kisspeptin-1

Patients with mutations that inactivate kisspeptin signaling are infertile. Kisspeptin-54, the major circulating isoform of kisspeptin in humans, potently stimulates reproductive hormone secretion in humans. Animal studies suggest that kisspeptin is involved in generation of the luteinizing hormone surge, which is required for ovulation; therefore, we hypothesized that kisspeptin-54 could be used to trigger egg maturation in women undergoing in vitro fertilization therapy.. Following superovulation with recombinant follicle-stimulating hormone and administration of gonadotropin-releasing hormone antagonist to prevent premature ovulation, 53 women were administered a single subcutaneous injection of kisspeptin-54 (1.6 nmol/kg, n = 2; 3.2 nmol/kg, n = 3; 6.4 nmol/kg, n = 24; 12.8 nmol/kg, n = 24) to induce a luteinizing hormone surge and egg maturation. Eggs were retrieved transvaginally 36 hours after kisspeptin injection, assessed for maturation (primary outcome), and fertilized by intracytoplasmic sperm injection with subsequent transfer of one or two embryos.. Egg maturation was observed in response to each tested dose of kisspeptin-54, and the mean number of mature eggs per patient generally increased in a dose-dependent manner. Fertilization of eggs and transfer of embryos to the uterus occurred in 92% (49/53) of kisspeptin-54-treated patients. Biochemical and clinical pregnancy rates were 40% (21/53) and 23% (12/53), respectively.. This study demonstrates that a single injection of kisspeptin-54 can induce egg maturation in women with subfertility undergoing in vitro fertilization therapy. Subsequent fertilization of eggs matured following kisspeptin-54 administration and transfer of resulting embryos can lead to successful human pregnancy.. ClinicalTrials.gov NCT01667406.

Topics: Adult; Dose-Response Relationship, Drug; Female; Fertility Agents, Female; Fertilization in Vitro; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Humans; Infertility; Kisspeptins; Oocytes; Ovulation; Pregnancy; Pregnancy, Ectopic; Recombinant Proteins

Reproductive sterilization by surgical gonadectomy is strongly advocated to help manage animal populations, especially domesticated pets, and to prevent reproductive behaviors and diseases. This study explored the use of a single-injection method to induce sterility in female animals as an alternative to surgical ovariohysterectomy. The idea was based on our recent finding that repetitive daily injection of estrogen into neonatal rats disrupted hypothalamic expression of Kisspeptin (KISS1), the neuropeptide that triggers and regulates pulsatile secretion of GnRH. Neonatal female rats were dosed with estradiol benzoate (EB) either by daily injections for 11 days or by subcutaneous implantation of an EB-containing silicone capsule designed to release EB over 2-3 weeks. Rats treated by either method did not exhibit estrous cyclicity, were anovulatory, and became infertile. The EB-treated rats had fewer hypothalamic Kisspeptin neurons, but the GnRH-LH axis remained responsive to Kisspeptin stimulation. Because it would be desirable to use a biodegradable carrier that is also easier to handle, an injectable EB carrier was developed from PLGA microspheres to provide pharmacokinetics comparable to the EB-containing silicone capsule. A single neonatal injection of EB-microspheres at an equivalent dosage resulted in sterility in the female rat. In neonatal female Beagle dogs, implantation of an EB-containing silicone capsule also reduced ovarian follicle development and significantly inhibited KISS1 expression in the hypothalamus. None of the treatments produced any concerning health effects, other than infertility. Therefore, further development of this technology for sterilization in domestic female animals, such as dogs and cats is worthy of investigation.

Topics: Animals; Animals, Domestic; Cat Diseases; Cats; Dog Diseases; Dogs; Estrogens; Female; Gonadotropin-Releasing Hormone; Hypothalamus; Infertility; Kisspeptins; Rats; Sterilization

The homeodomain transcription factor SIX3 is a known regulator of eye, nose, and forebrain development, and has recently been implicated in female reproduction. Germline heterozygosity of SIX3 is sufficient to cause subfertility, but the cell populations that mediate this role are unknown. The neuropeptide kisspeptin is a critical component of the reproductive axis and plays roles in sexual maturation, ovulation, and the maintenance of gonadotropin secretion. We used Cre-Lox technology to remove Six3 specifically from kisspeptin neurons in mice to test the hypothesis that SIX3 in kisspeptin neurons is required for reproduction. We found that loss of Six3 in kisspeptin neurons causes subfertility and estrous cycle irregularities in females, but no effect in males. Overall, we find that SIX3 expression in kisspeptin neurons is an important contributor to female fertility.

Topics: Animals; Eye Proteins; Female; Gonadotropin-Releasing Hormone; Homeobox Protein SIX3; Homeodomain Proteins; Infertility; Kisspeptins; Male; Mice; Nerve Tissue Proteins; Neurons; Neuropeptides; Reproduction

Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. The current findings that intrauterine lipopolysaccharide is absorbed in systemic circulation and attenuates ovarian cyclic activities could provide a basis for developing novel treatments to improve fertility.. Uterine inflammatory diseases are a major cause of infertility in humans and domestic animals. Circulating lipopolysaccharide (LPS), a bacterial endotoxin causing uterine inflammation, reportedly downregulates the hypothalamic-pituitary-gonadal axis to mediate ovarian dysfunction. In contrast, the mechanism whereby intrauterine LPS affects ovarian function has not been fully clarified. This study aimed to elucidate whether uterine exposure to LPS downregulates hypothalamic kisspeptin gene (Kiss1) expression, gonadotropin release, and ovarian function. Uterine inflammation was induced by intrauterine LPS administration to ovary-intact and ovariectomized female rats. As a result, plasma LPS concentrations were substantially higher in control rats until 48 h post injection, and the estrous cyclicity was disrupted with a prolonged diestrous phase. Three days post injection, the number of Graafian follicles and plasma estradiol concentration were reduced in LPS-treated rats, while numbers of Kiss1-expressing cells in the anteroventral periventricular nucleus and arcuate nucleus (ARC) were comparable in ovary-intact rats. Four days post injection, ovulation rate and plasma progesterone levels reduced significantly while gene expression of interleukin1β and tumor necrosis factor α was upregulated in the ovaries of LPS-treated rats that failed to ovulate. Furthermore, the number of Kiss1-expressing cells in the ARC and pulsatile luteinizing hormone (LH) release were significantly reduced in ovariectomized rats 24 h post injection. In conclusion, these results indicate that intrauterine LPS is absorbed in systemic circulation and attenuates ovarian function. This detrimental effect might be caused, at least partly, by the inhibition of ARC Kiss1 expression and LH pulses along with an induction of ovarian inflammatory response.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Estradiol; Female; Infertility; Inflammation; Kisspeptins; Lipopolysaccharides; Luteinizing Hormone; Progesterone; Rats; Tumor Necrosis Factor-alpha

Kisspeptin has been identified as a key regulatory protein in the release of gonadotropin-releasing hormone (GnRH), which subsequently increases gonadotropin secretion during puberty to establish reproductive function and regulate the hypothalamic-pituitary-gonadal axis. The effects of variants in the

Topics: Adult; Female; Genetic Loci; Genetic Variation; Gonadotropin-Releasing Hormone; High-Throughput Nucleotide Sequencing; Humans; Infertility; Kisspeptins; Receptors, Kisspeptin-1; Receptors, LHRH; Reproduction

The relationship between elevated prolactin and infertility has been known for a long time, but the specific mechanism by which prolactin inhibited reproduction had been uncertain. The discovery of kisspeptin has provided novel insights into how prolactin might cause infertility, with extensive evidence that elevated prolactin inhibits secretion of kisspeptin, resulting in hypogonadotropic hypogonadism, and infertility. More recent data suggest that a converse relationship might also exist, with evidence that kisspeptin influences prolactin secretion. This brief review will examine the relationship between kisspeptin and prolactin from each of these two perspectives: the well-characterized inhibitory effect of prolactin on kisspeptin neurons and the more recent concept that kisspeptin neurons are involved in the control of prolactin secretion.

Topics: Animals; Female; Humans; Infertility; Kisspeptins; Luteinizing Hormone; Male; Mice; Prolactin; Puberty; Rats; Signal Transduction

Topics: Endocrinology; Faculty, Medical; Female; History, 20th Century; History, 21st Century; Humans; Infertility; Kisspeptins; Laboratory Personnel; Male; Pregnancy; Reproductive Techniques, Assisted; United Kingdom

The intent of this contribution is to provide an update of the progress we have made towards developing a method/treatment to permanently sterilize cats. Our approach employs two complementary methodologies: RNA interference (RNAi) to silence genes involved in the central control of reproduction and a virus-based gene therapy system intended to deliver RNAi selectively to the hypothalamus (where these genes are expressed) via the systemic administration of modified viruses. We selected the hypothalamus because it contains neurons expressing Kiss1 and Tac3, two genes essential for reproduction and fertility. We chose the non-pathogenic adeno-associated virus (AAV) as a vector whose tropism could be modified to target the hypothalamus. The issues that must be overcome to utilize this vector as a delivery vehicle to induce sterility include modification of the wild-type AAV to target the hypothalamic region of the brain with a simultaneous reduction in targeting of peripheral tissues and non-hypothalamic brain regions, identification of RNAi targets that will effectively reduce the expression of Kiss1 and Tac3 without off-target effects, and determination if neutralizing antibodies to the AAV serotype of choice are present in cats. Successful resolution of these issues will pave the way for the development of a powerful tool to induce the permanent sterility in cats.

Topics: Animals; Cats; Contraception; Dependovirus; Gene Expression; Gene Silencing; Genetic Engineering; Genetic Vectors; Hypothalamus; Infertility; Kisspeptins; Neurokinin B; RNA Interference

Kisspeptin neuropeptides are encoded by the Kiss1 gene and play a critical role in the regulation of the mammalian reproductive axis. Kiss1 neurones are found in two locations in the rodent hypothalamus: one in the arcuate nucleus (ARC) and another in the RP3V region, which includes the anteroventral periventricular nucleus (AVPV). Detailed mapping of the fibre distribution of Kiss1 neurones will help with our understanding of the action of these neurones in other regions of the brain. We have generated a transgenic mouse in which the Kiss1 coding region is disrupted by a CRE-GFP transgene so that expression of the CRE recombinase protein is driven from the Kiss1 promoter. As expected, mutant mice of both sexes are sterile with hypogonadotrophic hypogonadism and do not show the normal rise in luteinising hormone after gonadectomy. Mutant female mice do not develop mature Graafian follicles or form corpora lutea consistent with ovulatory failure. Mutant male mice have low blood testosterone levels and impaired spermatogenesis beyond the meiosis stage. Breeding Kiss-CRE heterozygous mice with CRE-activated tdTomato reporter mice allows fluorescence visualisation of Kiss1 neurones in brain slices. Approximately 80-90% of tdTomato positive neurones in the ARC were co-labelled with kisspeptin and expression of tdTomato in the AVPV region was sexually dimorphic, with higher expression in females than males. A small number of tdTomato-labelled neurones was also found in other locations, including the lateral septum, the anterodorsal preoptic nucleus, the amygdala, the dorsomedial and ventromedial hypothalamic nuclei, the periaquaductal grey, and the mammillary nucleus. Three dimensional visualisation of Kiss1 neurones and fibres by CLARITY processing of whole brains showed an increase in ARC expression during puberty and higher numbers of Kiss1 neurones in the caudal region of the ARC compared to the rostral region. ARC Kiss1 neurones sent fibre projections to several hypothalamic regions, including rostrally to the periventricular and pre-optic areas and to the lateral hypothalamus.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Brain; Female; Genitalia; Hypothalamus, Anterior; Infertility; Kisspeptins; Male; Mice, Transgenic; Neural Pathways; Neuroanatomical Tract-Tracing Techniques; Neurons; Organ Size; Sexual Maturation

Landmark studies have shown that mutations in kisspeptin and the kisspeptin receptor (Kiss1r) result in reproductive dysfunction in humans and genetically altered mouse models. However, because kisspeptin and its receptor are present in target cells of the central and peripheral reproductive axis, the precise location(s) for the pathogenic signal is unknown. The study described herein shows that the kisspeptin-Kiss1r signaling pathway in the GnRH neuron is singularly critical for both the onset of puberty as well as the attainment of normal reproductive function. In this study, we directly test the hypothesis that kisspeptin neurons regulate GnRH secretion through the activation of Kiss1r on the plasma membrane of GnRH neurons. A GnRH neuron-specific Kiss1r knockout mouse model (GKirKO) was generated, and reproductive development and phenotype were assessed. Both female and male GKirKO mice were infertile, having low serum LH and FSH levels. External abnormalities such as microphallus and decreased anogenital distance associated with failure of preputial gland separation were present in GKirKO males. A delay in pubertal onset and abnormal estrous cyclicity were observed in female GKirKO mice. Taken together, these data provide in vivo evidence that Kiss1r in GnRH neurons is critical for reproductive development and fertility.

Topics: Animals; Estrogens; Estrous Cycle; Female; Gonadotrophs; Gonadotropin-Releasing Hormone; Hypogonadism; Hypothalamus; Infertility; Kisspeptins; Male; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Neurons; Ovary; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Signal Transduction; Testis

Topics: Animals; Female; Follicle Stimulating Hormone; Humans; Hyperprolactinemia; Infertility; Kisspeptins; Luteinizing Hormone; Male; Pregnancy

The Kiss1 gene encodes a 145-amino acid pre-peptide, kisspeptin, which is cleaved into smaller peptides of 54, 14, 13, and 10 amino acids. This chapter reviews in detail the effects of kisspeptin on gonadotropin secretion in non-human mammals. Studies of kisspeptin's effects have included both acute and chronic administration regimens via a number of administration routes. Acute kisspeptin stimulates gonadotropin secretion in a wide range of species of non-human mammals, including rats, mice, hamsters, sheep, pigs, goats, cows, horses, and monkeys. In general, the stimulatory effect of kisspeptin treatment is more pronounced for LH than FSH secretion. Kisspeptin is thought to exert its stimulatory effects on LH and FSH release via stimulation of GnRH release from the hypothalamus, since pre--administration of a GnRH antagonist prevents kisspeptin's stimulation of gonadotropin secretion. Although the kisspeptin receptor is also expressed on anterior pituitary cells of some species, and incubation of anterior pituitary cells with high concentrations of kisspeptin can stimulate in vitro LH release, the contribution of direct effects of kisspeptin on the pituitary is thought to be negligible in vivo. Continuous kisspeptin administration results in reduced sensitivity to the effects of kisspeptin, in some species. This desensitization is thought to occur at the level of the kisspeptin receptor, since the response of the pituitary gland to exogenous GnRH is maintained. Overall, the findings discussed in this chapter are invaluable to the understanding of the reproductive role of kisspeptin and the potential therapeutic uses of kisspeptin for the treatment of fertility disorders.

Topics: Animals; Cattle; Cricetinae; Follicle Stimulating Hormone; Goats; Gonadotropin-Releasing Hormone; Gonadotropins; Haplorhini; Horses; Infertility; Kisspeptins; Luteinizing Hormone; Mice; Pituitary Gland, Anterior; Rats; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sheep

Signaling between kisspeptin and its receptor, G-protein-coupled receptor 54 (Gpr54), is now recognized as being essential for normal fertility. However, the key cellular location of kisspeptin-Gpr54 signaling is unknown. Here we create a mouse with a GnRH neuron-specific deletion of Gpr54 to assess the role of gonadotropin-releasing hormone (GnRH) neurons. Mutant mice are infertile, fail to go through puberty and exhibit markedly reduced gonadal size and follicle-stimulating hormone levels alongside GnRH neurons that are unresponsive to kisspeptin. In an attempt to rescue the infertile phenotype of global Gpr54⁻/⁻ mutants, we use BAC transgenesis to target Gpr54 to the GnRH neurons. This results in mice with normal puberty onset, estrous cyclicity, fecundity and a recovery of kisspeptin's stimulatory action upon GnRH neurons. Using complimentary cell-specific knockout and knockin approaches we demonstrate here that the GnRH neuron is the key site of kisspeptin-Gpr54 signaling for fertility.

Topics: Animals; Female; Fertility; Gene Expression Regulation, Developmental; Gene Knock-In Techniques; Gonadotropin-Releasing Hormone; Hypothalamus; Infertility; Kisspeptins; Mice; Mice, Knockout; Neurons; Organ Size; Ovary; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sexual Maturation; Signal Transduction

The G protein-coupled receptor Gpr54 and its ligand metastin (derived from the Kiss1 gene product kisspeptin) are key gatekeepers of sexual maturation. Gpr54 knockout mice demonstrate hypogonadotropic hypogonadism, but until recently, the phenotype of Kiss1 knockout mice was unknown. This report describes the reproductive phenotypes of mice carrying targeted deletions of Kiss1 or Gpr54 on the same genetic background. Both Kiss1 and Gpr54 knockout mice are viable but infertile and have abnormal sexual maturation; the majority of males lack preputial separation, and females have delayed vaginal opening and absence of estrous cycling. Kiss1 and Gpr54 knockout males have significantly smaller testes compared with controls. Gpr54 knockout females have smaller ovaries and uteri than wild-type females. However, Kiss1 knockout females demonstrate two distinct phenotypes: half have markedly reduced gonadal weights similar to those of Gpr54 knockout mice, whereas half exhibit persistent vaginal cornification and have gonadal weights comparable with those of wild-type females. FSH levels in both Kiss1 and Gpr54 knockout males and females are significantly lower than in controls. When injected with mouse metastin 43-52, a Gpr54 agonist, Gpr54 knockout mice fail to increase gonadotropins, whereas Kiss1 knockout mice respond with increased gonadotropin levels. In summary, both Kiss1 and Gpr54 knockout mice have abnormal sexual maturation consistent with hypogonadotropic hypogonadism, although Kiss1 knockout mice appear to be less severely affected than their receptor counterparts. Kiss1 knockout females demonstrate a bimodal phenotypic variability, with some animals having higher gonadal weight, larger vaginal opening, and persistent vaginal cornification.

Topics: Animals; Female; Gonadotropins; Hypogonadism; Infertility; Intracellular Signaling Peptides and Proteins; Kisspeptins; Male; Mice; Mice, Knockout; Organ Size; Ovary; Peptide Fragments; Phenotype; Protein Serine-Threonine Kinases; Proteins; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sexual Maturation; Spermatozoa; Testis; Testosterone

The recent finding that the hormone kisspeptin plays a pivotal role in the onset of puberty is one of the biggest discoveries in human reproductive biology in 30 years. Mutations in the receptor for kisspeptin cause humans and mice to fail to reach puberty and to be sterile. It is the first time since the identification of gonadotrophin-releasing hormone that a single gene is found to have such a dramatic effect on reproduction. This discovery opens new possibilities in the treatment of reproductive disorders such as delayed or advanced puberty, infertility and sex hormone-dependent cancers.

Topics: Animals; Humans; Infertility; Kisspeptins; Mice; Proteins; Puberty; Rats; Receptors, G-Protein-Coupled; Receptors, Galanin; Receptors, Kisspeptin-1; Reproduction; Tumor Suppressor Proteins