kiss1-protein--human and Hypogonadism

Kisspeptin is a 54- amino acid peptide that acts as a ligand of a receptor called GPR54 which is basically a transmembrane receptor that spins seven times across the cell membrane and coupled with G-protein. Kisspeptin regulates the development of reproductive functions and the onset of puberty in human and other mammals by acting at the brain, hypothalamus, pituitary and gonad levels of reproductive axis. Kisspeptin is also involved in regulation of trophoblastic invasion during pregnancy, ovulation, and sperm hyperactivation. Inactivating mutations in human kisspeptin gene (KISS1) cause idiopathic hypogonadotropic hypogonadism. Some mutations in human kisspeptin receptor gene (KISS1R) make the receptor inactive which result in idiopathic hypogonadotropic hypogonadism. Some mutations in human KISS1R gene make the receptor prematurely activated and result in the development of central precocious puberty. Central precocious puberty is also caused by some mutations in human KISS1 gene that make the kisspeptin resistant to degradation. This leads to an increased basal kisspeptin level and subsequently the development of central precocious puberty. Higher kisspeptin level has been detected in the serum and plasma of central precocious puberty patients, which suggest that serum or plasma kisspeptin level can be used as a marker for diagnosis of central precocious puberty.

Topics: Animals; Female; Humans; Hypogonadism; Kisspeptins; Pregnancy; Puberty; Puberty, Precocious; Receptors, Kisspeptin-1; Reproduction

In recent years, it has been found that kisspeptin plays some key roles in the physiological processes of the brain, such as gender differentiation, positive and negative feedback of sex hormones, onset of puberty, and transduction of energy signals in the body, which suggests that kisspeptin may be a key molecule for the maturation and regulation of female reproductive function. In addition to the systemic roles of the kisspeptin, its local roles in reproductive organs are constantly being discovered. With the discovery that kisspeptin is involved in the pathological process of reproductive endocrine diseases such as isolated hypogonadotropic hypogonadism (IHH), polycystic ovary syndrome (PCOS), premature ovarian failure (POF) and pathological hyperprolactinemia, exogenous application of kisspeptin to solve reproductive problems has become a new hot topic. The review focuses on the research progress of kisspeptin in the female reproductive system, especially on its application in assisted reproduction.

Topics: Female; Gonadal Steroid Hormones; Humans; Hyperprolactinemia; Hypogonadism; Kisspeptins; Polycystic Ovary Syndrome; Pregnancy; Primary Ovarian Insufficiency; Reproductive Techniques, Assisted

Distinguishing between constitutional delay of growth and puberty (CDGP) and congenital hypogonadotropic hypogonadism (CHH) may be challenging. CDGP and CHH appear to belong to the same clinical spectrum (with low sex hormones and low LH and FSH), although one is classically transient and known as a self-limited form of delayed puberty (CDGP) while the other is permanent (CHH). Thus, the clinical history and the outcomes of these two conditions require different approaches, and an adequate and timely management for the patients is mandatory. Since the initial presentation of CDGP and CHH is almost identical and given the similarities of CDGP and partial forms of CHH (i.e. patients with partial and early interrupted pubertal development) the scientific community has been struggling to find some diagnostic tests able to allow an accurate differential diagnosis between these two conditions in delayed puberty. In this review we provide an up to date insight on the tests available, their meanings and accuracy, as well as some clues to effectively differentiate between constitutional pubertal delay and pathologic CHH.

Topics: Diagnosis, Differential; Female; Follicle Stimulating Hormone; Growth Disorders; Humans; Hypogonadism; Inhibins; Insulin; Kisspeptins; Luteinizing Hormone; Male; Proteins; Puberty, Delayed; Receptors, Peptide; Receptors, Transforming Growth Factor beta; Sex Factors; Time Factors

Calorie restriction and overtraining are increasingly seen in young men who suffer from increasing societal pressure to attain a perceived ideal male body image. The resulting energy deficit can lead to multiple endocrine consequences, including suppression of the male gonadal axis.. We reviewed the literature, including two unpublished cases.. Hypogonadotropic hypogonadism can occur in the context of energy deprivation in young otherwise healthy men and may be underrecognized. The evidence suggests that gonadal axis suppression and associated hormonal abnormalities represent an adaptive response to increased physiological stress and total body energy deficit. The pathophysiology likely involves hypothalamic suppression due to dysregulation of leptin, ghrelin and pro-inflammatory cytokines. The gonadal axis suppression is functional, because it can be reversible with weight gain. Treatment should focus on reversing the existing energy deficit to achieve a healthy body weight, including psychiatric input where required.

Topics: Adolescent; Adult; Anorexia; Body Weight; Exercise; Ghrelin; Humans; Hypogonadism; Insulin-Like Growth Factor I; Kisspeptins; Male; Testosterone; Weight Loss; Young Adult

The endocrine and exocrine functions of the gonads are controlled by the gonadotrope axis, whose master regulator is the hypothalamic decapeptide GnRH. The Kisspeptin/Neurokinin B (Kp/NkB) neuronendocrine system is the main physiologic regulator of GnRH neurons. The Kp/NkB system is currently considered the key mediator for the hypothalamic negative feedback exerted by sex steroids and prolactin, as well as by various metabolic signals. Intrinsic alterations or regulatory abnormalities of Kp/NkB system lead to various gonadotrope axis puberty and fertility dysfunctions. Molecular inactivations of Kp/NkB system actors are associated with some forms of congenital hypogonadotropic hypogonadism without anosmia. The Kp/NkB System is also involved in a few forms of precocious puberty. Finally, the Kp/NKB system is also implicated in gonadotrope axis alterations leading to functional hypothalamic amenorrhea or hyperprolactinemia. NkB is particularly and directly involved in vasomotor menopausal hot flushes mechanism. Various Kp/NkB agonist/antagonist compounds have been developed during the last ten years, and are currently being evaluated in humans. These molecules have potential applications not only in rare genetic diseases with Kp/NkB alterations, but also in various gonadotrope axis-related diseases or in vitro fertilization. The administration of NkB antagonists in menopausal women represents a real therapeutic advance because of their impressive effect in controlling vasomotor menopausal hot flushes.

Topics: Animals; Female; Gonadotrophs; Gonadotropin-Releasing Hormone; Gonads; Hormone Antagonists; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Male; Menopause; Neurokinin B; Pituitary-Adrenal System; Sexual Maturation

Kisspeptins are a family of neuropeptides whose identification has become one of the biggest discoveries in reproductive endocrinology during the past decade. Kisspeptins act upstream of GnRH as high-level mediators of the reproductive axis.. The authors performed a search of all publications on kisspeptin since its discovery in 1996. A full appraisal of the expanding literature concerning kisspeptin is beyond the scope of this review. This article therefore aims to cover the principle human studies outlining kisspeptin action in human physiology and to discuss the key findings, describing kisspeptin's potential as a therapeutic target in human reproduction.. The identification of the kisspeptin signaling pathway has greatly advanced the study of reproductive endocrinology. Building on a large body of animal data, a growing number of human studies have shown that exogenous kisspeptin can stimulate physiological gonadotropin responses in both healthy subjects and those with disorders of reproduction. There is an increasing appreciation that kisspeptin may act as a signal transmitter between metabolic status and reproductive function. Future work is likely to involve investigation of novel kisspeptin analogs and further exploration of role of neurokinin B and dynorphin on the kisspeptin-GnRH axis.

Topics: Amenorrhea; Animals; Female; Humans; Hypogonadism; Kisspeptins; Menopause; Ovulation; Reproduction

The neuropeptide kisspeptin, encoded by the Kiss1 gene, is required for mammalian puberty and fertility. Examining the development of the kisspeptin system contributes to our understanding of pubertal progression and adult reproduction and sheds light on possible mechanisms underlying the development of reproductive disorders, such as precocious puberty or hypogonadotropic hypogonadism. Recent work, primarily in rodent models, has begun to study the development of kisspeptin neurons and their regulation by sex steroids and other factors at early life stages. In the brain, kisspeptin is predominantly expressed in two areas of the hypothalamus, the anteroventral periventricular nucleus and neighboring periventricular nucleus (pre-optic area in some species) and the arcuate nucleus. Kisspeptin neurons in these two hypothalamic regions are differentially regulated by testosterone and estradiol, both in development and in adulthood, and also display differences in their degree of sexual dimorphism. In this chapter, we discuss what is currently known and not known about the ontogeny, maturation, and sexual differentiation of kisspeptin neurons, as well as their regulation by sex steroids and other factors during development.

Topics: Adult; Animals; Anterior Thalamic Nuclei; Arcuate Nucleus of Hypothalamus; Estradiol; Female; Gene Expression Regulation; Humans; Hypogonadism; Kisspeptins; Male; Puberty; Puberty, Precocious; Reproduction; Sex Characteristics; Testosterone

Mutations in the genes encoding the neuropeptides kisspeptin and neurokinin B, as well as their receptors, are associated with gonadotrophin-releasing hormone (GnRH) deficiency and a failure to initiate and/or progress through puberty. Although the total number of patients studied to date is small, mutations in the kisspeptin pathway appear to result in lifelong GnRH deficiency. Mice with mutations in kisspeptin and the kisspeptin receptor, Kiss1(-/-) and Kiss1r(-/-), respectively, appear to be phenocopies of the human with abnormal sexual maturation and infertility. In contrast, mutations in the neurokinin B pathway lead to a more variable adult reproductive phenotype, with a subset of hypogonadotrophic individuals demonstrating paradoxical recovery of reproductive function later in life. While 'reversal' remains poorly understood, the ability to recover reproductive function indicates that neurokinin B may play different roles in the initiation of sexual maturation compared with the maintenance of adult reproductive function. Mice with mutations in the gene encoding the neurokinin B receptor, Tacr3, have abnormal oestrous cycles and subfertility but, similar to their human counterparts, appear less severely affected than mice with kisspeptin deficiency. Further investigations into the interaction between the kisspeptin and neurokinin B pathways will reveal key insights into how GnRH neuronal modulation occurs at puberty and throughout reproductive life.

Topics: Animals; Disease Models, Animal; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Mice; Neurokinin B; Signal Transduction

The aim of this review is to summarize recent advances regarding the genetic components of the complex and coordinated process of puberty, an update of the genes implicated in disorders of puberty, the endocrinologic changes of puberty, and influences of environment in the light of our current understanding of the mechanism of the onset of puberty.. The timing of puberty varies greatly in the general population among ethnic groups throughout the world, suggesting the genetic control of puberty. Several studies on the pathological conditions of pubertal onset provide unique information about the interactions of either the genetic susceptibility of or environmental influences on hypothalamic control of pubertal onset. However, these findings suggested that no isolated pathway or external factor is solely responsible for the neuroendocrine control of puberty.. Puberty is initiated by gonadotropin-releasing hormone from the hypothalamus followed by a complex sequence of endocrine changes and is regulated by both genetic and environmental factors. New attempts to use genetics and genomics might enhance our understanding of the spectrum of pubertal development.

Topics: Adolescent; Age Factors; Child; DNA-Binding Proteins; Endocrine Disruptors; Environmental Exposure; Female; Genetic Variation; Gonadal Hormones; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Male; Nutritional Status; Obesity; Polymorphism, Single Nucleotide; Puberty; RNA-Binding Proteins; Sexual Maturation

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

Kisspeptins, the peptide products of the KiSS-1 gene, bind to the G protein coupled receptor 54 (GPR54). Since 2003, research has revealed the important role of kisspeptins in initiating puberty, timing puberty and regulating fertility in adulthood. Specific mutations in GPR54 gene cause either delayed/absent puberty or precocious puberty. The KiSS-1/GPR54 system stimulates the gonadotrophin releasing hormone (GnRH) neurons and is involved in the feedback regulation of the HPG axis by gonadal steroids. Different hypothalamic nuclei are involved in negative (arcuate nucleus; ARC) and positive (anteroventral periventricular nucleus; AVPV) feedback in mice. Continuous administration of kisspeptins down-regulates the HPG axis. During pregnancy, kisspeptins are secreted from the placenta in large amounts and are responsible for the physiological invasion of primary human trophoblast. Kisspeptins have been administered to normal male and female individuals as well as to women with hypothalamic secondary amenorrhoea. In all cases, gonadotrophin secretion was potently stimulated. Kisspeptin antagonists have been synthesized to successfully suppress GnRH and gonadotrophin release. These agonists and antagonists appear as valuable new tools for manipulating the HPG axis and are promising drugs for future treatment. The scope of this review highlights the role of kisspeptins in regulating gonadotrophin secretion and explores their possible therapeutic use.

Topics: Adult; Animals; Female; Gene Expression Regulation; Gonadal Disorders; Gonadotropins; Humans; Hypogonadism; Kisspeptins; Male; Mice; Mutation; Pregnancy; Rats; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1

Since 2003, kisspeptin and its receptor (KISS1R, also called GPR54) are recognized as major actors of the gonadotrope axis. Mutations of genes encoding the peptide or the receptor have been identified in patients with precocious puberty or hypogonadotropic hypogonadism. They are strong stimulators of GnRH neurons and are involved in various mechanisms regulating gonadotrope axis as puberty induction or positive and negative feedback regulation on the gonadotrope axis by gonadal steroids. They also mediated some metabolic or environmental signals on the reproduction axis. Kisspeptins are synthesized and secreted by hypothalamic nuclei located in the arcuate nucleus (ARC) and anteroventral periventricular nucleus (AVPV). This system is complex because neurons located in the ARC coexpress many neuromediators such as neurokinin B and dynorphin, involved in the control of gonadotrope axis. During pregnancy, kisspeptins are also secreted by placenta and should be involved in trophoblastic invasion. After kisspeptin administration to male and female animals as well as to women with hypothalamic secondary amenorrhoea, they are able to stimulate GnRH and gonadotrophin secretion. Then, kisspeptin agonists appear as valuable new tools in treatment for reproduction troubles. The aim of this review is to clarify the role of kisspeptins in regulating gonadotrophin secretion and explores their possible therapeutic use.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Female; Gonadotropin-Releasing Hormone; Gonadotropins; Humans; Hypogonadism; Kisspeptins; Male; Mice; Mice, Knockout; Mutation; Neurons; Paraventricular Hypothalamic Nucleus; Placenta; Pregnancy; Puberty; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction

Kisspeptins (Kps), were first found to regulate the hypothalamopituitary-gonadal axis (HPG) axis in 2003, when two groups-demonstrated that mutations of GPR54 causes idiopathic hypogonadotropic hypogonadism (IHH) characterized by delayed puberty. Objective of this review is to highlight both animal and human discoveries in KISS1/GPR54 system in last decade and extrapolate the therapeutic potential in humans from till date human studies.. A systematic review of international scientific literature by a search of PUBMED and the authors files was done for Kp in reproduction, metabolic control & signal transduction.. None Patient(s): In human studies--normal subjects patients with HH, or HA.. Effects of Kp on puberty, brain sexual maturation, regulation of GnRH secretion, metabolic control of GnRH Neurons (N).. Kps/GPR54 are critical for brain sexual maturation, puberty and regulation of reproduction. Kps have been implicated in mediating signals to GnRH N--positive and negative feedback, metabolic input. Ability of Kp neurons to coordinate signals impinging on the HPG axis makes it one of most important regulators of reproductive axis since GnRH N's lack many receptors, with Kp neurons serving as upstream modulators.. Kps have proven as pivotal regulators of the reproduction, with the ability to integrate signals from both internal and external sources. Knowledge about signaling mechanisms involved in Kp stimulation of GnRH and with human studies has made it possible that therapeutically available Kp agonists/antagonists may be used for treatment of delayed puberty/HH, Hypothalamic amenorrhea and in prevention of spread of malignant ovarian/gonadal malignancies along with uses in some eating disorders.

Topics: Animals; Brain; Feedback, Physiological; Follicular Phase; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Hypothalamus; Kisspeptins; Male; Mutation; Neurons; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sexual Maturation

Recently discovered neuropeptide called kisspeptin is thought to be an essential gatekeeper in control of reproduction. Kisspeptin, the product of KiSS-1 gene and its G protein-coupled receptor GPR54 play a master role in the puberty period and fertility. This 54 amino acid peptide known also as metastatin, because of its metastasis suppression ability is also implicated in tumour biology. Kisspeptin/GPR54 system activates the hypothalamus-pituitary-ovarian axis. Its mechanism is not clearly understood. Kisspeptin influence is found above more at the level of hypothalamus but also at the pituitary and ovaries level. Kisspeptin can directly stimulate GnRH secretion from arcuate nucleus of hypothalamus. It is thought that kisspeptin plays an essential role in the metabolic regulation of fertility. In negative energy balance conditions an expression of KiSS-1 gene is decreased. Inactivating GPR54 mutations cause hypogonadotropic hypogonadism in humans. Simultaneously, mutations which increase GPR54 signalling are connected with gonadotropin-dependent premature puberty. Lately, possible therapeutic role of kisspeptin administration has been discussed. It was stated that kisspeptin might be used to manipulate the hypothalamic-pituitary-gonadal axis in humans. However, further studies are essential to reveal the exact mechanism and role of GPR54 agonists and antagonists applications. Moreover, the role of kisspeptin in the aspect of detection and treatment of specific cancers should be discovered.

Topics: Female; Gene Expression; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Hypothalamus; Kisspeptins; Mutation; Ovary; Pituitary Gland; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Tumor Suppressor Proteins

The complex organization and regulation of the human hypothalamic-pituitary-gonadal axis render it susceptible to dysfunction in the face of a variety of genetic insults, leading to different degrees of hypogonadotrophic hypogonadism (HH). Although the genetic basis of some HH was recognized more than 60 years ago the first specific pathogenic defect, in the KAL1 gene, was only identified within the last 20 years. In the past decade, the rate of genetic discovery has dramatically accelerated, with defects in more than 10 genes now associated with HH. Several themes have emerged as the genetic basis of HH has gradually been uncovered, including the association of some genes such as FGFR1, FGF8, PROK2 and PROKR2, both with HH in association with hyposmia/anosmia (Kallmann syndrome) and with normosmic HH, thus blurring the clinical distinction between ontogenic and purely functional defects in the axis. Many examples of digenic inheritance of HH have also been reported, sometimes producing variable reproductive and accessory phenotypes within a family with non-Mendelian inheritance patterns. In strictly normosmic HH, human genetics has made a particularly dramatic impact in the past 6 years through homozygosity mapping in consanguineous families, first through identification of a key role for kisspeptin in triggering GnRH release, and very recently through demonstration of a critical role for neurokinin B in normal sexual maturation. This review summarises current understanding of the genetic architecture of HH, as well as its diagnostic and mechanistic implications.

Topics: Consanguinity; Extracellular Matrix Proteins; Female; Fibroblast Growth Factor 8; Gastrointestinal Hormones; Gonads; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kallmann Syndrome; Kisspeptins; Male; Nerve Tissue Proteins; Neurokinin B; Neuropeptides; Phenotype; Receptor, Fibroblast Growth Factor, Type 1; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, Neurokinin-3; Receptors, Peptide; Sexual Maturation; Tumor Suppressor Proteins

The kisspeptin-GPR54 signaling complex is a key gatekeeper of human sexual maturation. Kisspeptins, encoded by the KISS1 gene, constitute a powerful stimulus for gonadotropin-releasing hormone-induced gonadotropin secretion. In addition, the KISS1 gene is a target for regulation by gonadal steroids in both sexes. The increase in hypothalamic kisspeptin expression at puberty is believed to contribute to maturation of the reproductive axis. Homozygous or compound heterozygous loss-of-function mutations in the GPR54 gene have been identified in familial and sporadic patients with isolated hypogonadotropic hypogonadism without olfactory abnormalities. In addition, mice with targeted deletions of Kiss1 or Gpr54 have a similar failure of sexual maturation. Study of these mutations provides an important contribution in the understanding of the role of the kisspeptin/GPR54 system in the control of human puberty development and reproductive function.

Topics: Amino Acid Sequence; Animals; Brain; Calcium Channels; Female; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Male; Mice; Mice, Knockout; Molecular Sequence Data; Mutation; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

In recent years, a substantial body of evidence has accumulated suggesting that the hypothalamic peptide hormone kisspeptin and its cognate receptor, G-protein-coupled receptor 54, play a fundamental role both as gatekeepers for the initiation of puberty and in the regulation of the hypothalamic-pituitary-gonadal axis. This review discusses the physiology of the kisspeptin signalling system and examines how findings from animal and human studies have contributed to our understanding of the pathophysiology of idiopathic hypogonadotropic hypogonadism.

Topics: Animals; Female; Gonads; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Macaca mulatta; Male; Placenta; Pregnancy; Puberty; Rats; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Kisspeptin has emerged as a critical player in the initiation of puberty and reproductive function. In humans, inactivating mutations of the kisspeptin receptor result in hypogonadotrophic hypogonadism and kisspeptin receptor activating mutations cause precocious puberty. Kisspeptin potently stimulates the release of gonadotrophins predominantly through the release of gonadotrophin-releasing hormone (GnRH). Here we review the data from animal and human studies exploring the role of kisspeptin in the regulation of the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin signalling presents a novel target for therapeutic manipulation of the HPG axis.

Topics: Animals; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Puberty; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

What controls puberty remains largely unknown and current gene mutations account for only about one-third of the apparently genetic cases of idiopathic hypogonadotropic hypogonadism. Lately important developments have occurred in this field.. Substantial variation in clinical expression, from complete anosmia and hypogonadotropic hypogonadism to delayed puberty and normosmia, of the same Kallmann syndrome gene defects including in newer ones (FGF8 and CHD7) continues to be repeatedly observed. Digenic or oligogenic inheritance becomes another feature of Kallmann syndrome. Recent reports of mutations in TAC3 or TACR3 [encoding neurokinin B (NKB) and its receptor, NK3R, respectively] provided compelling evidence for the involvement of NKB signaling in puberty. This energized the field to understand the exact mechanism through which NKB signaling exerts its effects. With the important findings from these recent studies in association with the substantial data from kisspeptin studies in the last 6 years a sketch of GnRH pulse generator has emerged in which NKB signaling appears to play a key role.. Autozygosity mapping may continue helping identify the other genes including those upstream to the GnRH pulse generator in this complex and elusive developmental process.

Topics: Animals; Female; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Male; Mice; Neurokinin B; Pituitary-Adrenal System; Puberty; Puberty, Delayed; Tumor Suppressor Proteins

Hypogonadism occurs commonly in men with type 2 diabetes (T2DM) and severe obesity. Current evidence points to a decreased secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus and thereby decreased secretion of gonadotropins from the pituitary gland as a central feature of the pathophysiology in these men. Hyperglycaemia, inflammation, leptin and oestrogen-related feedback have been proposed to make aetiological contributions to the hypogonadotropic hypogonadism of T2DM. However, the neuroendocrine signals that link these factors with modulation of GnRH neurons have yet to be identified. Kisspeptins play a central role in the modulation of GnRH secretion and, thus, downstream regulation of gonadotropins and testosterone secretion in men. Inactivating mutations of the kisspeptin receptor have been shown to cause hypogonadotropic hypogonadism in man, whilst an activating mutation is associated with precocious puberty. Data from studies in experimental animals link kisspeptin expression with individual factors known to regulate GnRH secretion, including hyperglycaemia, inflammation, leptin and oestrogen. We therefore hypothesise that decreased endogenous kisspeptin secretion is the common central pathway that links metabolic and endocrine factors in the pathology of testosterone deficiency seen in men with obesity and T2DM. We propose that the kisspeptin system plays a central role in integrating a range of metabolic inputs, thus constituting the link between energy status with the hypothalamic-pituitary-gonadal axis, and put forward potential clinical studies to test the hypothesis.

Topics: Animals; Diabetes Mellitus, Type 2; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Male; Obesity; Tumor Suppressor Proteins

Puberty is the developmental period during which rapid somatic changes and attainment of reproductive capacity take place. The sine qua non event for the onset of puberty is the increase in pulsatile GnRH release from GnRH neurons. GnRH neurons originate in the nasal placode and migrate, from the nasal compartment through the basal forebrain, before they attain their positions in the hypothalamus. Failure of GnRH neurons to migrate, mainly due to genetic alterations, leads to a clinical condition defined congenital hypogonadotropic hypogonadism. Other important factors demonstrated a permissive role for GnRH secretion at time of puberty, such as the kisspeptin G-protein-coupled receptor 54 (GPR54, now called KISS-1R) and its ligand, as well as neurokinin B (NKB) and the neurokinin 3 (NK3) receptor. Kisspeptin and neurokinin B colocalized in a subset of hypothalamic neurons that regulate GnRH secretion by GnRH neurons. Indeed, loss of function mutations in the above-mentioned and other genes result in hypogonadotrophic hypogonadism with absence of pubertal development. In males, pubertal increase of androgens levels seems to be required for the attainment of a normal bone density and male-specific body composition. However, also genetic variants of genes involved in bone metabolism as well as in osteoblast/osteoclast activation are associated to bone mineral density.

Topics: Androgens; Animals; Body Composition; Bone Density; Cell Movement; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Leptin; Male; Neurons; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Tumor Suppressor Proteins

In 2003, three groups around the world simultaneously discovered that KISS1R (GPR54) is a key gatekeeper of sexual maturation in both mice and men. Developmental changes in the expression of the ligand for KISS1R, kisspeptin, support its critical role in the pubertal transition. In addition, kisspeptin, a powerful stimulus of GNRH-induced gonadotropin secretion and may modulate both positive and negative sex steroid feedback effects at the hypothalamic level. Genetic studies in humans have revealed both loss-of-function and gainof-function mutations in patients with idiopathic hypogonadotropic hypogonadism and precocious puberty respectively. This review examines the kisspeptin/KISS1R pathway in the reproductive system.

Topics: Animals; Female; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Mice; Mutation; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Sexual Maturation; Tumor Suppressor Proteins

In order to find novel modulators of gonadotrophin-releasing hormone (GnRH) secretion, genetic tools were employed in patients with idiopathic hypogonadotrophic hypogonadism (IHH). Mutations in a G-protein coupled receptor, GPR54, were identified, making this receptor a genetic determinant and indisputable gatekeeper of normal reproductive function. This article places these investigations into historical context and reviews some of the new findings relevant to this pathway.

Topics: Animals; Gene Deletion; Gonadotropin-Releasing Hormone; Heterotrimeric GTP-Binding Proteins; Humans; Hypogonadism; Kisspeptins; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Idiopathic hypogonadotropic hypogonadism (IHH) is a condition characterized by absence of sexual maturation in the setting of low sex steroids and low/normal gonadotropins. Despite its rarity, considerable genetic heterogeneity and phenotypic variability exists in this disorder. Loss of function mutations in a G protein coupled receptor, GPR54, have been shown to cause IHH. Although mutations in GPR54 are not a common cause of this condition, patients bearing mutations are critical to explore genotype-phenotype correlations and gene function. In this review, we will examine the human genetics studies of GPR54, the phenotypic implications of mutations in this gene, and the emerging roles of the kisspeptin/GPR54 pathway.

Topics: DNA Mutational Analysis; Female; Genetic Heterogeneity; Genotype; Humans; Hypogonadism; Kisspeptins; Models, Biological; Neurosecretory Systems; Phenotype; Pregnancy; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Syndrome; Tumor Suppressor Proteins

Neurons that synthesize and secrete the decapeptide gonadotropin-releasing hormone-1 (GnRH-1) to control the reproductive axis originate in the olfactory placode/vomeronasal organ of the olfactory system of mammals and migrate along vomeronasal nerves to the cribriform plate, which marks the boundary between the peripheral olfactory system and the forebrain. Migrating GnRH-1 neurons follow a branch of the vomeronasal nerve caudally into the hypothalamus, where they extend processes to the median eminence and halt their migration. The release of GnRH-1 into the capillaries of the median eminence starts the cascade that activates pituitary gonadotropin (luteinizing hormone and follicle-stimulating hormone) production and secretion. Failure of these neurons to complete their migration results in failure of the reproductive axis. In some cases, failed migration is linked to the loss of the sense of smell (anosmia). The mechanisms that regulate migration of GnRH-1 neurons along this complex pathway are incompletely understood. Recent studies have revealed an important role for a series of strategically located soluble factors that regulate different aspects of GnRH-1 neuron migration at specific locations along their migratory route. This review focuses on the different mechanisms used by these factors to regulate migration of GnRH-1 neurons.

Topics: Animals; Cell Movement; Chemokine CXCL12; Chemokines, CXC; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kallmann Syndrome; Kisspeptins; Nerve Growth Factors; Netrin-1; Neurons; Olfactory Pathways; Prosencephalon; Protein Precursors; Receptors, CXCR4; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Although the functions of kisspeptin originally were believed to be restricted to metastasis suppression, a novel role for this protein was discovered in 2003. Loss-of-function mutations in its receptor, GPR54, were found to cause absence of puberty and hypogonadotropic hypogonadism in humans. Mice with targeted deletions of GPR54 also have a hypogonadotropic phenotype, confirming the important role of this ligand-receptor family in the control of puberty and reproductive function. Since these discoveries, the peptide products of the KISS1 gene have been shown to be powerful stimulators of the gonadotropic axis. This review examines the role of kisspeptins and GPR54 in reproductive function.

Topics: Animals; Estrous Cycle; Female; Gene Expression Regulation, Developmental; Gonadal Steroid Hormones; Gonadotropins; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Hypothalamus; Kisspeptins; Male; Mice; Mutation; Placenta; Proteins; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Puberty is controlled by genetic and environmental factors. This review examines the genetic basis for puberty by evaluating known gene mutations associated with disordered puberty in humans. At present, at least 17 different single-gene mutations are recognized as being associated with delayed or absent puberty in humans. Several of these genes are involved in the development of the olfactory nervous system, with mutations typically resulting in anosmia/hyposmia and hypogonadotropic hypogonadism, otherwise known as Kallmann syndrome. The biological basis for the association between smell and fertility is strong as development of the gonadotropin-releasing hormone (GnRH) neurons, responsible for regulating fertility, is intricately associated with development of the olfactory system. Other gene mutations, including the recently discovered kisspeptin-GPR54 signalling system, affect puberty by directly or indirectly modulating the functioning of the GnRH neurons and pituitary gonadotrophs. Together, these single-gene mutations are presently estimated to account for approximately 30% of individuals with disorders of puberty.. A large number of different genes are involved in the complex process of bringing about reproductive competency. In addition to the genetic mutations associated with precocious and delayed puberty, the oligogenic aetiology of these conditions is being increasingly appreciated.

Topics: Brain; Child Development; Embryonic Development; Humans; Hypogonadism; Infant; Kallmann Syndrome; Kisspeptins; Mutation; Puberty; Puberty, Delayed; Puberty, Precocious; Tumor Suppressor Proteins

Isolated hypogonadotropic hypogonadism (IHH) is defined by a complete or partial impaired secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In the regulation of the gonadotropic axis, the gonadotropin-releasing hormone (GnRH) and its receptor have evolved as a central element in fetal life, at puberty, and for reproduction in adulthood. GnRH resistance due to GnRH receptor (GnRHR) germ-line mutations was the first genetic alteration identified in patients with IHH. GnRHR mutated receptors are associated with impaired GnRH binding, intracellular trafficking or ligand-induced signal transduction, leading to various degrees of LH and FSH deficiency. Loss-of-function mutations of the GnRH receptor account for 50% of familial cases of IHH without anosmia. In 2003, mutations of GPR54 were identified in patients with IHH, opening a new pathway in the physiological regulation of puberty and reproduction. Kisspeptins, which are the natural ligands of GPR54, are potent stimulators of the LH and FSH secretion via the control of GnRH secretion or modulation of the pituitary response to GnRH stimulation. Genotype-phenotype correlations in IHH due to GnRHR and GPR54 mutations indicate that similar mutations may lead to a variable phenotype and suggest that the pituitary might have its own pubertal maturation independent from GnRH. These two causes of IHH result in a more quantitative than qualitative defect of the gonadotropic axis activation. Molecular genetics of IHH has led to a major breakthrough in the neuroendocrine regulation of the gonadotropic axis. New insights into the understanding of the initiation of puberty and in the therapeutic management of defects of the gonadotropic axis have emerged from these studies.

Topics: Animals; Disease Models, Animal; Follicle Stimulating Hormone; Gene Expression Regulation; Genotype; Germ-Line Mutation; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Phenotype; Protein Precursors; Protein Processing, Post-Translational; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, LHRH; Signal Transduction; Tumor Suppressor Proteins

Isolated hypogonadotropic hypogonadism (IHH) is characterized by complete or partial failure of pubertal development due to impaired secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In the molecular pathogenesis of IHH, the gonadotropin-releasing hormone receptor (GnRH-R) and associated proteins have evolved as a central element. GnRH-R germline mutations were among the first genetic alterations identified in patients with IHH. These mutations are associated with impaired GnRH binding, ligand-induced signal transduction, or both, leading to various degrees of LH and FSH deficiency. As GnRH-R mutations explain several but not all cases of IHH, the search for new candidate genes continued in informative families. In 2003, mutations of the KiSS-1-derived peptide receptor GPR54 were identified in patients with IHH, opening a new pathway in the physiologic regulation of puberty and reproduction. GPR54 is putatively involved in the control of GnRH secretion. IHH associated with impaired olfactory function (Kallmann syndrome) may be caused by mutations of the X-chromosomal KAL1 (encoding anosmin) or the fibroblast growth factor receptor 1 genes (FGFR1), both leading to agenesis of olfactory and GnRH-secreting neurons. In addition to their clinical and diagnostic value, the identification of genetic and functional alterations in IHH helps to unravel the complex regulation of the gonadotropic axis.

Topics: Extracellular Matrix Proteins; Follicle Stimulating Hormone; Germ-Line Mutation; Gonadotropin-Releasing Hormone; Gonadotropins; Humans; Hypogonadism; Kallmann Syndrome; Kisspeptins; Luteinizing Hormone; Nerve Tissue Proteins; Proteins; Receptor Protein-Tyrosine Kinases; Receptor, Fibroblast Growth Factor, Type 1; Receptors, Fibroblast Growth Factor; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, LHRH; Receptors, Neuropeptide; Tumor Suppressor Proteins

The acquisition of a sexually dimorphic phenotype is a critical event in mammalian development. Hypogonadotropic hypogonadism (HH) results from impaired secretion of GnRH. The patients display with delayed puberty, micropenis and cryptorchidism in the male reflecting gonadotropin insufficiency, and amenorrhea in the female. Kallmann's syndrome (KS) is defined by the association of HH and anosmia or hyposmia (absent smelling sense). Segregation analysis in familial cases has demonstrated diverse inheritance patterns, suggesting the existence of several genes regulating GnRH secretion. The X-linked form of the disease was associated with a genetic defect in the KALI gene located on the Xp22.3 region. KAL1 gene encodes an extracellular matrix glycoprotein anosmin-1, which facilitates neuronal growth and migration. Abnormalities in the migratory processes of the GnRH neurons with the olfactory neurons explain the association of HH with anosmia. Recently, mutations in the FGF recepteur 1 (FGFR1) gene were found in KS with autosomal dominant mode of inheritance. The role of FGFR1 in the function of reproduction requires further investigation. Besides HH with anosmia, there are isolated HH (IHH). No human GnRH mutations have been reported although hypogonadal mice due to a GnRH gene deletion exist. In patients with idiopathic HH and without anosmia an increasing number of GnRH receptor (GnRHR) mutations have been described which represent about 50% of familial cases. The clinical features are highly variable and there is a good relationship between genotype and phenotype. A complete loss of function is associated with the most severe phenotype with resistance to pulsatile GnRH treatment, absence of puberty and cryptorchidism in the male. In contrast, milder loss of function mutations causes incomplete failure of pubertal development. The preponderant role of GnRH in the secretion of LH by the gonadotrophs explains the difference of the phenotype between male and female with partial GnRH resistance. Affected females can have spontaneous telarche and normal breast development while affected males exhibit no pubertal development but normal testis volume, a feature described as "fertile-eunuch". High-dose pulsatile GnRH has been used to induce ovulation. Another gene, called GPR54, responsible for idiopathic HH has been recently described by segregation analysis in two different consanguineous families. The GPR54 gene is an orphan receptor, and its putative ligand i

Topics: Amino Acid Sequence; Animals; Cell Movement; Consanguinity; Extracellular Matrix Proteins; Female; Genetic Heterogeneity; Genotype; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Hypothalamus; Kallmann Syndrome; Kisspeptins; Male; Mice; Models, Biological; Molecular Sequence Data; Nerve Tissue Proteins; Olfaction Disorders; Phenotype; Point Mutation; Proteins; Receptor Protein-Tyrosine Kinases; Receptor, Fibroblast Growth Factor, Type 1; Receptors, Fibroblast Growth Factor; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, LHRH; Receptors, Neuropeptide; Tumor Suppressor Proteins

Some patients with idiopathic hypogonadotropic hypogonadism (IHH) undergo spontaneous activation of their hypothalamic-pituitary-gonadal axis resulting in normalization of steroidogenesis and/or gametogenesis, a phenomenon termed reversal.. To assess the responsiveness of the GnRH neuronal network to exogenous kisspeptin administration in IHH patients who have undergone reversal.. Six men with congenital IHH and evidence for reversal.. Subjects underwent q10 min blood sampling to measure GnRH-induced LH secretion at baseline and in response to iv boluses of kisspeptin (0.24-2.4 nmol/kg) and GnRH (75 ng/kg).. Individuals with sustained reversal of their hypogonadotropism (spontaneous LH pulses) responded to exogenous kisspeptin with a GnRH-induced LH pulse. Individuals who had reversal but then subsequently suffered relapse of their IHH (loss of spontaneous LH pulsatility) did not respond to kisspeptin.. The ability of kisspeptin to stimulate a GnRH-induced LH pulse correlates with the presence of endogenous LH pulses. These data suggest that reversal of hypogonadotropism, and by extension sexual maturation, may be due to the acquisition of kisspeptin responsiveness.

Topics: Adolescent; Adult; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Hormone Replacement Therapy; Hormones; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Puberty; Reproduction; Sexual Maturation; Signal Transduction; Testosterone; Young Adult

Low serum testosterone is commonly observed in men with type 2 diabetes (T2DM), but the neuroendocrine pathophysiology remains to be elucidated.. The hypothalamic neuropeptide kisspeptin integrates metabolic signals with the reproductive axis in animal models. We hypothesized that administration of exogenous kisspeptin-10 will restore luteinizing hormone (LH) and testosterone secretion in hypotestosteronaemic men with T2DM.. Five hypotestosteronaemic men with T2DM (age 33·6 ± 3 years, BMI 40·6 ± 6·3, total testosterone 8·5 ± 1·0 nmol/l, LH 4·7 ± 0·7 IU/l, HbA1c 7·4±2%, duration of diabetes <5 years) and seven age-matched healthy men. EXPERIMENT 1: Mean LH increased in response to intravenous administration of kisspeptin-10 (0·3 mcg/kg bolus) both in healthy men (5·5 ± 0·8 to 13·9 ± 1·7 IU/l P < 0·001) and in men with T2DM (4·7 ± 0·7 to 10·7 ± 1·2 IU/l P = 0·02) with comparable ΔLH (P = 0·18). EXPERIMENT 2: Baseline 10-min serum sampling for LH and hourly testosterone measurements were performed in four T2DM men over 12 h. An intravenous infusion of kisspeptin-10 (4 mcg/kg/h) was administered for 11 h, 5 days later. There were increases in LH (3·9 ± 0·1 IU/l to 20·7 ± 1·1 IU/l P = 0·03) and testosterone (8·5 ± 1·0 to 11·4 ± 0·9 nmol/l, P = 0·002). LH pulse frequency increased from 0·6 ± 0·1 to 0·9 ± 0 pulses/h (P = 0·05) and pulsatile component of LH secretion from 32·1 ± 8·0 IU/l to 140·2 ± 23·0 IU/l (P = 0·007).. Kisspeptin-10 administration increased LH pulse frequency and LH secretion in hypotestosteronaemic men with T2DM in this proof-of-concept study, with associated increases in serum testosterone. These data suggest a potential novel therapeutic role for kisspeptin agonists in enhancing endogenous testosterone secretion in men with T2DM and central hypogonadism.

Topics: Adult; Animals; Diabetes Mellitus, Type 2; Enzyme-Linked Immunosorbent Assay; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Infusions, Intravenous; Kisspeptins; Luteinizing Hormone; Male; Testosterone; Treatment Outcome

Metabolism has a role in determining the time of pubertal development and fertility. Nonetheless, molecular/cellular pathways linking metabolism/body weight to puberty/reproduction are unknown. The KNDy (Kisspeptin/Neurokinin B/Dynorphin) neurons in the arcuate nucleus of the hypothalamus constitute the GnRH (gonadotropin-releasing hormone) pulse generator. We previously created a mouse model with a whole-body targeted deletion of nescient helix-loop-helix 2 (Nhlh2; N2KO), a class II member of the basic helix-loop-helix family of transcription factors. As this mouse model features pubertal failure and late-onset obesity, we wanted to study whether NHLH2 represents a candidate molecule to link metabolism and puberty in the hypothalamus. Exome sequencing of a large Idiopathic Hypogonadotropic Hypogonadism cohort revealed obese patients with rare sequence variants in NHLH2, which were characterized by in-silico protein analysis, chromatin immunoprecipitation, and luciferase reporter assays. In vitro heterologous expression studies demonstrated that the variant p.R79C impairs Nhlh2 binding to the Mc4r promoter. Furthermore, p.R79C and other variants show impaired transactivation of the human KISS1 promoter. These are the first inactivating human variants that support NHLH2's critical role in human puberty and body weight control. Failure to carry out this function results in the absence of pubertal development and late-onset obesity in humans.

Topics: Adolescent; Adult; Amino Acid Sequence; Animals; Arcuate Nucleus of Hypothalamus; Basic Helix-Loop-Helix Transcription Factors; Female; Genetic Variation; Humans; Hypogonadism; Kisspeptins; Male; Metabolic Networks and Pathways; Mice; Models, Molecular; Mutant Proteins; Mutation, Missense; Obesity; Pedigree; Promoter Regions, Genetic; Protein Conformation; Transcriptional Activation; Young Adult

Hypogonadotropic hypogonadism (HH) is hypogonadism due to either hypothalamic or pituitary dysfunction. While gonadotropin-releasing hormone (GnRH) can directly test pituitary function, no specific test of hypothalamic function exists. Kisspeptin-54 (KP54) is a neuropeptide that directly stimulates hypothalamic GnRH release and thus could be used to specifically interrogate hypothalamic function. Congenital HH (CHH) is typically due to variants in genes that control hypothalamic GnRH neuronal migration or function. Thus, we investigated whether KP54 could accurately identify hypothalamic dysfunction in men with CHH.. Men with CHH (n = 21) and healthy eugonadal men (n = 21) received an intravenous bolus of either GnRH (100 μg) or KP54 (6.4 nmol/kg), on 2 occasions, and were monitored for 6 h after administration of each neuropeptide.. Maximal luteinizing hormone (LH) rise after KP54 was significantly greater in healthy men (12.5 iU/L) than in men with CHH (0.4 iU/L; p < 0.0001). KP54 more accurately differentiated CHH men from healthy men than GnRH (area under receiver operating characteristic curve KP54: 1.0, 95% CI 1.0-1.0; GnRH: 0.88, 95% CI 0.76-0.99). Indeed, all CHH men had an LH rise <2.0 iU/L following KP54, whereas all healthy men had an LH rise >4.0 iU/L. Anosmic men with CHH (i.e., Kallmann syndrome) had even lower LH rises after KP54 than did normosmic men with CHH (p = 0.017). Likewise, men identified to have pathogenic/likely pathogenic variants in CHH genes had even lower LH rises after KP54 than other men with CHH (p = 0.035).. KP54 fully discriminated men with CHH from healthy men. Thus, KP54 could be used to specifically interrogate hypothalamic GnRH neuronal function in patients with CHH.

Topics: Adult; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kallmann Syndrome; Kisspeptins; Luteinizing Hormone; Male

Energy balance is closely related to reproductive function, wherein hypothalamic kisspeptin mediates regulation of the energy balance. However, the central mechanism of kisspeptin in the regulation of male reproductive function under different energy balance states is unclear. Here, high-fat diet (HFD) and exercise were used to change the energy balance to explore the role of leptin and inflammation in the regulation of kisspeptin and the hypothalamic-pituitary-testis (HPT) axis.. Four-week-old male C57BL/6 J mice were randomly assigned to a normal control group (n = 16) or an HFD (n = 49) group. After 10 weeks of HFD feeding, obese mice were randomly divided into obesity control (n = 16), obesity moderate-load exercise (n = 16), or obesity high-load exercise (n = 17) groups. The obesity moderate-load exercise and obesity high-load exercise groups performed exercise (swimming) for 120 min/day and 120 min × 2 times/day (6 h interval), 5 days/week for 8 weeks, respectively.. Compared to the mice in the normal group, in obese mice, the mRNA and protein expression of the leptin receptor, kiss, interleukin-10 (IL-10), and gonadotropin-releasing hormone (GnRH) decreased in the hypothalamus; serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone levels and sperm quality decreased; and serum leptin, estradiol, and tumor necrosis factor-α (TNF-α) levels and sperm apoptosis increased. Moderate- and high-load exercise effectively reduced body fat and serum leptin levels but had the opposite effects on the hypothalamus and serum IL-10 and TNF-α levels. Moderate-load exercise had anti-inflammatory effects accompanied by increased mRNA and protein expression of kiss and GnRH in the hypothalamus and increased serum FSH, LH, and testosterone levels and improved sperm quality. High-load exercise also promoted inflammation, with no significant effect on the mRNA and protein expression of kiss and GnRH in the hypothalamus, serum sex hormone level, or sperm quality. Moderate-load exercise improved leptin resistance and inflammation and reduced the inhibition of kisspeptin and the HPT axis in obese mice. The inflammatory response induced by high-load exercise may counteract the positive effect of improving leptin resistance on kisspeptin and HPT.. During changes in energy balance, leptin and inflammation jointly regulate kisspeptin expression on the HPT axis.

Topics: Animals; Energy Metabolism; Hypogonadism; Hypothalamus; Infertility, Male; Inflammation; Inflammation Mediators; Kisspeptins; Leptin; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Reproduction; Signal Transduction

Metabolic stress resulting from either lack or excess of nutrients often causes infertility in both sexes. Kisspeptin-neurokinin B-dynorphin A (KNDy) neurons in the arcuate nucleus (ARC) has been suggested to be a key players in reproduction via direct stimulation of the pulsatile gonadotropin-releasing hormone (GnRH) and subsequent gonadotropin release in mammalian species. In this study, we investigated the effect of high-fat diet (HFD) on hypothalamic KNDy gene expression to examine the pathogenic mechanism underlying obesity-induced infertility in male and female rats. Male and female rats at 7 weeks of age were fed with either a standard or HFD for 4 months. In the male rats, the HFD caused a significant suppression of ARC Kiss1 and Pdyn gene expressions, but did not affect the plasma luteinizing hormone (LH) levels and sizes of the morphology of the testis and epididymis. In the female rats, 58% of the HFD-fed female rats exhibited irregular estrous cycles, whereas the remaining rats showed regular cycles. Two of the 10 rats that showed HFD-induced irregular estrous cycles showed profound suppression of LH pulse frequency and the number of ARC Kiss1-expressing cells, whereas the other females showed normal LH pulses and ARC Kiss1 expression. Our finding shows that suppression of ARC Kiss1 expression might be the initial pathological change of hypogonadotropic hypogonadism in HFD-fed male rats, while the obese-related infertility in the female rats may be mainly induced by KNDy-independent pathways. Taken together, ARC kisspeptin neurons in male rats may be susceptible to HFD-induced obesity compared with those in female rats.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Diet, High-Fat; Dynorphins; Female; Gonadal Steroid Hormones; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Metabolic Diseases; Neurokinin B; Neurons; Obesity; Rats; Rats, Wistar

The present study aimed to evaluate whether novel conditional kisspeptin neuron-specific Kiss1 knockout (KO) mice utilizing the Cre-loxP system could recapitulate the infertility of global Kiss1 KO models, thereby providing further evidence for the fundamental role of hypothalamic kisspeptin neurons in regulating mammalian reproduction. We generated Kiss1-floxed mice and hypothalamic kisspeptin neuron-specific Cre-expressing transgenic mice and then crossed these two lines. The conditional Kiss1 KO mice showed pubertal failure along with a suppression of gonadotropin secretion and ovarian atrophy. These results indicate that newly-created hypothalamic Kiss1 KO mice obtained by the Cre-loxP system recapitulated the infertility of global Kiss1 KO models, suggesting that hypothalamic kisspeptin, but not peripheral kisspeptin, is critical for reproduction. Importantly, these Kiss1-floxed mice are now available and will be a valuable tool for detailed analyses of roles of each population of kisspeptin neurons in the brain and peripheral kisspeptin-producing cells by the spatiotemporal-specific manipulation of Cre expression.

Topics: Animals; Hypogonadism; Hypothalamus; Kisspeptins; Mice; Mice, Knockout; Mice, Transgenic; Neurons; Phenotype

Restoration of spermatogenesis and fertility is a major issue to be solved in male mammals with hypogonadotropic hypogonadism. Kiss1 knockout (KO) male mice are postulated to be a suitable animal model to investigate if hormonal replacement rescues spermatogenesis in mammals with this severe reproductive hormone deficiency, because KO mice replicate the hypothalamic disorder causing hypogonadism. The present study investigated whether testosterone supplementation was able to restore spermatogenesis and in vitro fertilization ability in Kiss1 KO mice. To this end, spermatogenesis, in vitro fertilization ability of Kiss1 KO sperm, and preimplantation development of wild-type embryos inseminated with Kiss1 KO sperm, were examined. The newly generated Kiss1 KO male mice showed infertility with cryptorchidism. Subcutaneous testosterone supplementation for 6 weeks restored plasma and intratesticular testosterone levels, elicited testicular descent, and induced complete spermatogenesis from spermatocytes to elongated spermatids in the testis, resulting in an increase in epididymal sperm number in testosterone-supplemented Kiss1 KO male mice. Epididymal sperm derived from the testosterone-supplemented Kiss1 KO mice showed normal in vitro fertilization ability, and the fertilized eggs showed normal preimplantation development, while the males failed to impregnate females. These results suggest that the failure of spermatogenesis in Kiss1 KO mice is mainly due to a lack of testosterone production, and that Kiss1 KO sperm are capable of fertilizing eggs if the animals receive the appropriate testosterone supplementation without local kisspeptin signaling in the testis and epididymis. Thus, testosterone supplementation would restore spermatogenesis of male mammals showing hypogonadotropic hypogonadism with genetic inactivation of the KISS1/Kiss1 gene.

Topics: Animals; Cells, Cultured; Female; Fertility; Fertilization in Vitro; Hypogonadism; Infertility, Male; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Knockout; Spermatogenesis; Testosterone

Metabolic syndrome (MetS) clusters cardiovascular and metabolic risk factors along with hypogonadism and erectile dysfunction. Lifestyle modifications including physical exercise (PhyEx) are well-known treatments for this condition. In this study, we analyzed the effect of PhyEx on hypothalamic-pituitary-testis axis and erectile function by use of an animal MetS model, previously established in rabbits fed a high-fat diet (HFD). Rabbits fed a regular diet (RD) were used as controls. A subset of both groups was trained on a treadmill. HFD rabbits showed typical MetS features, including HG (reduced T and LH) and impairment of erectile function. PhyEx in HFD rabbits completely restored plasma T and LH and the penile alterations. At testicular and hypothalamic levels, an HFD-induced inflammatory status was accompanied by reduced T synthesis and gonadotropin-releasing hormone (GnRH) immunopositivity, respectively. In the testis, PhyEx normalized HFD-related macrophage infiltration and increased the expression of steroidogenic enzymes and T synthesis. In the hypothalamus, PhyEx normalized HFD-induced gene expression changes related to inflammation and glucose metabolism, restored GnRH expression, particularly doubling mRNA levels, and regulated expression of molecules related to GnRH release (kisspeptin, dynorphin). Concerning MetS components, PhyEx significantly reduced circulating cholesterol and visceral fat. In multivariate analyses, cholesterol levels resulted as the main factor associated with MetS-related alterations in penile, testicular, and hypothalamic districts. In conclusion, our results show that PhyEx may rescue erectile function, exert anti-inflammatory effects on hypothalamus and testis, and increase LH levels and T production, thus supporting a primary role for lifestyle modification to combat MetS-associated hypogonadism and erectile dysfunction.

Topics: Animals; Blood Glucose; Cholesterol; Dynorphins; Erectile Dysfunction; Gonadotropin-Releasing Hormone; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Luteinizing Hormone; Macrophages; Male; Metabolic Syndrome; Physical Conditioning, Animal; Rabbits; Testis; Testosterone; Triglycerides; Tumor Necrosis Factor-alpha

Kisspeptin-neurokinin B (NKB)-dynorphin neurons are critical regulators of the hypothalamic-pituitary-gonadal axis. NKB and dynorphin are hypothesized to influence the frequency of GnRH pulses, whereas kisspeptin is hypothesized to be a generator of the GnRH pulse. How these neuropeptides interact remains unclear.. To probe the role of NKB in GnRH pulse generation and to determine the interactions between NKB, kisspeptin, and dynorphin in humans and mice with a complete absence of NKB.. Case/control.. Academic medical center.. Members of a consanguineous family bearing biallelic loss-of-function mutations in the gene encoding NKB and NKB-deficient mice.. Frequent blood sampling to characterize neuroendocrine profile and administration of kisspeptin, GnRH, and naloxone, a nonspecific opioid receptor antagonist used to block dynorphin.. LH pulse characteristics.. Humans lacking NKB demonstrate slow LH pulse frequency, which can be increased by opioid antagonism. Mice lacking NKB also demonstrate impaired LH secretion, which can be augmented with an identical pharmacologic manipulation. Both mice and humans with NKB deficiency respond to exogenous kisspeptin.. The preservation of LH pulses in the absence of NKB and dynorphin signaling suggests that both peptides are dispensable for GnRH pulse generation and kisspeptin responsiveness. However, NKB and dynorphin appear to have opposing roles in the modulation of GnRH pulse frequency.

Topics: Academic Medical Centers; Adolescent; Adult; Animals; Case-Control Studies; Child; Disease Models, Animal; Dynorphins; Female; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Mice; Mice, Knockout; Narcotic Antagonists; Neurokinin B; Neurons; Signal Transduction; Substance P; Treatment Outcome; Young Adult

Obesity is a metabolic disease with a serious health burden in children and adults, and it induces a variety of conditions including subfecundity. Sleeve gastrectomy showed encouraging results in terms of weight loss and improve quality of life, and this study aimed to determine whether sleeve gastrectomy could reverse obesity-induced impaired fertility in male Sprague-Dawley rats.. After 16 weeks of a chow diet (CD) or a high-fat diet (HFD) challenge, rats on the HFD were given a sleeve gastrectomy or sham operation and then fed an HFD for another 8 weeks. Serum glucose, insulin, lipids, sex hormone, sperm quality, inflammatory profile of the testis, and hypothalamic Kiss1 expression in the three study groups were compared.. Sleeve gastrectomy significantly decreased HFD-induced obesity and serum glucose and insulin levels. It also reversed the HFD-induced increase in teratozoospermia and decreases in sperm motility and progressive motility. Testicular morphological abnormalities were also improved after sleeve gastrectomy. Enzyme-linked immunosorbent assay showed that the expression of sex hormones increased after sleeve gastrectomy and that expression of inflammatory factors decreased. The HFD induced a hypothalamic inflammatory response that inhibited Kiss1 expression, which in turn mediated sex hormone expression. Sleeve gastrectomy treatment improved the hypothalamic response.. The results consistently showed that sleeve gastrectomy reversed obesity-induced male fertility impairment by decreasing the inflammatory responses of the testis and hypothalamus.

Topics: Animals; Diet, High-Fat; Disease Models, Animal; Gastrectomy; Humans; Hypogonadism; Hypothalamus; Insulin; Kisspeptins; Male; Obesity; Obesity, Morbid; Quality of Life; Rats; Rats, Sprague-Dawley; Sperm Motility; Testis; Weight Loss

Obesity may lead to male hypogonadism, the underlying mechanism of which remains unclear. In the present study, we established a murine model of male hypogonadism caused by high-fat diet-induced obesity to verify the following hypotheses: 1) an increased leptin level may be related to decreased secretion of GnRH in obese males, and 2) repression of kisspeptin/GPR54 in the hypothalamus, which is associated with increased leptin levels, may account for the decreased secretion of GnRH and be involved in secondary hypogonadism (SH) in obese males.. Male mice were fed high-fat diet for 19 weeks and divided by body weight gain into diet-induced obesity (DIO) and diet-induced obesity resistant (DIO-R) group. The effect of obesity on the reproductive organs in male mice was observed by measuring sperm count and spermatozoid motility, relative to testis and epididymis weight, testosterone levels, and pathologic changes. Leptin, testosterone, estrogen, and LH in serum were detected by ELISA method. Leptin receptor (Ob-R), Kiss1, GPR54, and GnRH mRNA were measured by real-time PCR in the hypothalamus. Expression of kisspeptin and Ob-R protein was determined by Western blotting. Expression of GnRH and GPR54 protein was determined by immunohistochemical analysis.. We found that diet-induced obesity decreased spermatozoid motility, testis and epididymis relative coefficients, and plasma testosterone and luteinizing hormone levels. An increased number and volume of lipid droplets in Leydig cells were observed in the DIO group compared to the control group. Significantly, higher serum leptin levels were found in the DIO and DIO-R groups. The DIO and DIO-R groups showed significant downregulation of the GnRH, Kiss1, GPR54, and Ob-R genes. We also found decreased levels of GnRH, kisspeptin, GPR54, and Ob-R protein in the DIO and DIO-R groups.. These lines of evidence suggest that downregulation of Ob-R and kisspeptin/GPR54 in the murine hypothalamus may contribute to male hypogonadism caused by high-fat diet-induced obesity.

Topics: Animals; Body Weight; Diet, High-Fat; Disease Models, Animal; Down-Regulation; Gonadotropin-Releasing Hormone; Hypogonadism; Hypothalamus; Kisspeptins; Leptin; Male; Mice; Obesity; Receptors, Kisspeptin-1; Receptors, Leptin; Sperm Motility; Testis

Mutations in the kisspeptin receptor (KISS1R) gene have been reported in a few patients with normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110).. To describe a female patient with nCHH and a novel homozygous KISS1R mutation and to assess the role of kisspeptin pathway to induce an ovulation by GnRH pulse therapy.. Observational study of a patient including genetic and kisspeptin receptor functions and treatment efficiency using a GnRH pump.. Response to pulsatile GnRH therapy.. A partial isolated gonadotropic deficiency was diagnosed in a 28-year-old woman with primary amenorrhea and no breast development. A novel homozygous c.953T>C variant was identified in KISS1R. This mutation led to substitution of leucine 318 for proline (p.Leu318Pro) in the seventh transmembrane domain of KISS1R. Signaling via the mutated receptor was profoundly impaired in HEK293-transfected cells. The mutated receptor was not detected on the membrane of HEK293-transfected cells. After several pulsatile GnRH therapy cycles, an LH surge with ovulation and pregnancy was obtained.. GnRH pulsatile therapy can induce an LH surge in a woman with a mutated KISS1R, which was previously thought to be completely inactivated in vivo.

Topics: Adult; Amenorrhea; Female; Gonadotropin-Releasing Hormone; HEK293 Cells; Homozygote; Humans; Hypogonadism; Kisspeptins; Loss of Function Mutation; Luteinizing Hormone; Ovulation; Pregnancy; Pulse Therapy, Drug; Receptors, Kisspeptin-1; Signal Transduction; Treatment Outcome

Patients with mutations of neurokinin B (NKB) and its receptor show hypogonadotrophic hypogonadism, but there is little evidence for the importance of this pathway in reproductive function in normal men, or its functional hierarchy with kisspeptin.. An open label study wherein men (n = 6) were administered the NK3R antagonist MLE4901 40 mg orally twice a day for 7 days. Kisspeptin-10 (0.3 μg/kg iv bolus) was given before and on day 7 of NK3R antagonist treatment.. Subjects were healthy men.. Reproductive hormones were measured before and during the NK3R antagonist administration, including frequent sampling on two occasions for analysis of pulsatile LH secretion.. LH, FSH and testosterone secretion were decreased during NK3R antagonist administration. LH showed a biphasic response, being reduced after 24 hours of treatment (4.5 ± 0.6 IU/L pretreatment to 1.7 ± 0.2 IU/L, P < .05), with partial recovery thereafter, but it was again decreased on day 7 (2.5 ± 0.6 IU/L, P < .05 vs pretreatment). FSH secretion was also suppressed, with a similar temporal pattern to that of LH. Testosterone secretion was decreased from 24 hours (18.4 ± 1.6 pretreatment vs 5.6 ± 1.5 nmol/L, P < .01) and remained suppressed throughout the treatment period. Analysis of LH pulsatility showed that both basal and pulsatile LH secretion were markedly suppressed but there was no detected change in LH pulse frequency. Kisspeptin-10 stimulated LH secretion, with similar responses before and during NK3R antagonist administration.. These data demonstrate a central role for NKB/NK3R in the physiological regulation of reproductive function in men, and that this is functionally upstream of kisspeptin-mediated GnRH secretion.

Topics: Adult; Follicle Stimulating Hormone; Gonadotropins; Heterocyclic Compounds, 2-Ring; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Mutation; Neurokinin B; Receptors, Neurokinin-3; Testosterone; Thiadiazoles; Young Adult

Embryonic stem cells (ESCs) have enormous potential as novel cell-based therapies, but their effectiveness depends on stem cell differentiation and specific signaling regulators, which remain poorly understood. In this study, a kisspeptin peptide (KP-10) was used at different dosages to determine whether rhesus macaque-derived tau GFP-Lyon ES cells underwent kisspeptin-specific neuronal differentiation. It was found that KP-10 exhibited an anti-proliferative effect on the cells and led to morphological changes and cellular differentiation consistent with neuronal stem cell (NSC) development. The cells differentiated into Gonadotrophin Releasing Hormone (GnRH) neuronal-like cell types in response to the KP-10 treatment. There has been a previously observed connection between kisspeptin signaling, GnRH neurons and their dysfunction found in congenital disorders like idiopathic hypogonadotropic hypogonadism (IHH). Although therapeutics are a still a far-off goal, the formation and development of GnRH-positive neuronal-like cells following the application of KP-10 to Lyon NSC cells opens the door for future NSC-based therapies to treat specific reproductive disorders.

Topics: Animals; Cell Differentiation; Embryonic Stem Cells; Gonadotropin-Releasing Hormone; Hypogonadism; Kisspeptins; Macaca mulatta; Neurons; Signal Transduction

In the human infundibular (arcuate) nucleus, a subpopulation of neurons coexpress kisspeptin and neurokinin B (NKB), 2 peptides required for normal reproductive function. A homologous group of neurons exists in the arcuate nucleus of rodents, termed KNDy neurons based on the coexpression of kisspeptin, NKB, and dynorphin. To study their function, we recently developed a method to selectively ablate KNDy neurons using NK3-SAP, a neurokinin 3 receptor agonist conjugated to saporin (SAP). Here, we ablated KNDy neurons in female rats to determine whether these neurons are required for estrous cyclicity and the steroid induced LH surge. NK3-SAP or Blank-SAP (control) was microinjected into the arcuate nucleus using stereotaxic surgery. After monitoring vaginal smears for 3-4 weeks, rats were ovariectomized and given 17β-estradiol and progesterone in a regimen that induced an afternoon LH surge. Rats were killed at the time of peak LH levels, and brains were harvested for NKB and dual labeled GnRH/Fos immunohistochemistry. In ovary-intact rats, ablation of KNDy neurons resulted in hypogonadotropic hypogonadism, characterized by low levels of serum LH, constant diestrus, ovarian atrophy with increased follicular atresia, and uterine atrophy. Surprisingly, the 17β-estradiol and progesterone-induced LH surge was 3 times higher in KNDy-ablated rats. Despite the marked increase in the magnitude of the LH surge, the number of GnRH or anterior ventral periventricular nucleus neurons expressing Fos was not significantly different between groups. Our studies show that KNDy neurons are essential for tonic levels of serum LH and estrous cyclicity and may play a role in limiting the magnitude of the LH surge.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dynorphins; Estradiol; Estrous Cycle; Female; Hypogonadism; Kisspeptins; Luteinizing Hormone; Neurokinin B; Neurons; Progesterone; Rats; Rats, Sprague-Dawley

Topics: Endocrinology; Humans; Hypogonadism; Kisspeptins; Klinefelter Syndrome

Male hypogonadism is defined as the deficiency of testosterone or sperm production synthesized by testicles or the deficiency of both. The reasons for hypogonadism may be primary, meaning testicular or secondary, meaning hypothalamohypophyseal. In hypogonadotropic hypogonadism (HH), there is indeficiency in gonadotropic hormones due to hypothalamic or hypophyseal reasons. Gonadotropin-releasing hormone (GnRH) is an important stimulant in releasing follicular stimulant hormone (FSH), mainly luteinizing hormone (LH). GnRH omitted is under the effect of many hormonal or stimulating factors. Kisspeptin is present in many places of the body, mostly in hypothalamic anteroventral periventricular nucleus and arcuate nucleus. Kisspeptin has a suppressor effect on the metastasis of many tumors such as breast cancer and malign melanoma metastases, and is called "metastin" for this reason. Kisspeptin is a strong stimulant of GnRH. In idiopathic hypogonadotropic hypogonadism (IHH) etiology, there is gonadotropic hormone release indeficiency which cannot be clearly described. A total of 30 male hypogonatropic hypogonadism diagnosed patients over 30 years of age who have applied to Haydarpasa Education Hospital Endocrinology and Metabolic Diseases Service were included in the study. Compared to the control group, the effect of kisspeptin on male patients with hypogonatropic hypogonadism and on insulin resistance developing in hypogonadism patients was investigated in our study. A statistically significant difference was detected between average kisspeptin measurements of the groups (p < 0.01). Kisspeptin measurement of the cases in the patient group were detected significantly high. No statistically significant relation was detected among kisspeptin and LH/FSH levels. Although a positive low relation was detected between kisspeptin measurements of patient group cases and homeostasis model assessment of insulin resistance (HOMA-IR) measurements, this relation was statistically insignificant. When the patient and control groups were compared for HOMA-IR, no statistically significant difference was detected. The reason for high kisspeptin levels in the patient group compared to the control group makes us consider that there may be a GPR54 resistance or GnRH neuronal transfer pathway defect. When patients and control groups were compared for HOMA-IR, the difference was not statistically significant. It is considered that kisspeptin is one of the reasons for hypogonatropic h

Topics: Adult; Humans; Hypogonadism; Insulin Resistance; Kisspeptins; Male; Young Adult

To investigate whether mutations in the KISS1 gene are present in 170 Chinese patients with idiopathic hypogonadotropic hypogonadism (IHH).. Mutational screening of the KISS1 gene was performed in 170 Chinese patients with IHH (133 male cases and 37 female cases) and 187 matched controls (94 males and 93 females).. Two known single-nucleotide polymorphisms (SNP), c. 58G > A in exon 1 and c. 242C > G in exon 2, were identified. However, no difference of genotype and allelic frequencies between cases and controls was observed.. The results suggest that mutations in the coding sequence of KISS1 are not common in patients with IHH in this Chinese population.

Topics: Adult; Asian People; China; DNA Mutational Analysis; Exons; Female; Genotype; Humans; Hypogonadism; Kisspeptins; Male; Middle Aged; Mutation; Polymorphism, Single Nucleotide

The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility and kisspeptin (KP) is a potent trigger of GnRH secretion from GnRH neurons. KP signals via KISS1R, a Gαq/11-coupled receptor, and mice bearing a global deletion of Kiss1r (Kiss1r(-/-)) or a GnRH neuron-specific deletion of Kiss1r (Kiss1r(d/d)) display hypogonadotropic hypogonadism and infertility. KISS1R also signals via β-arrestin, and in mice lacking β-arrestin-1 or -2, KP-triggered GnRH secretion is significantly diminished. Based on these findings, we hypothesized that ablation of Gαq/11 in GnRH neurons would diminish but not completely block KP-triggered GnRH secretion and that Gαq/11-independent GnRH secretion would be sufficient to maintain fertility. To test this, Gnaq (encodes Gαq) was selectively inactivated in the GnRH neurons of global Gna11 (encodes Gα11)-null mice by crossing Gnrh-Cre and Gnaq(fl/fl);Gna11(-/-) mice. Experimental Gnaq(fl/fl);Gna11(-/-);Gnrh-Cre (Gnaq(d/d)) and control Gnaq(fl/fl);Gna11(-/-) (Gnaq(fl/fl)) littermate mice were generated and subjected to reproductive profiling. This process revealed that testicular development and spermatogenesis, preputial separation, and anogenital distance in males and day of vaginal opening and of first estrus in females were significantly less affected in Gnaq(d/d) mice than in previously characterized Kiss1r(-/-) or Kiss1r(d/d) mice. Additionally, Gnaq(d/d) males were subfertile, and although Gnaq(d/d) females did not ovulate spontaneously, they responded efficiently to a single dose of gonadotropins. Finally, KP stimulation triggered a significant increase in gonadotropins and testosterone levels in Gnaq(d/d) mice. We therefore conclude that the milder reproductive phenotypes and maintained responsiveness to KP and gonadotropins reflect Gαq/11-independent GnRH secretion and activation of the neuroendocrine-reproductive axis in Gnaq(d/d) mice.. The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility. Over the last decade, several studies have established that the KISS1 receptor, KISS1R, is a potent trigger of GnRH secretion and inactivation of KISS1R on the GnRH neuron results in infertility. While KISS1R is best understood as a Gαq/11-coupled receptor, we previously demonstrated that it could couple to and signal via non-Gαq/11-coupled pathways. The present study confirms these findings and, more importantly, while it establishes Gαq/11-coupled signaling as a major conduit of GnRH secretion, it also uncovers a significant role for non-Gαq/11-coupled signaling in potentiating reproductive development and function. This study further suggests that by augmenting signaling via these pathways, GnRH secretion can be enhanced to treat some forms of infertility.

Topics: Animals; Blastocyst; Embryonic Development; Female; Gene Expression Profiling; Genitalia, Female; Genitalia, Male; Gonadal Steroid Hormones; Gonadotropin-Releasing Hormone; Gonadotropins, Pituitary; GTP-Binding Protein alpha Subunits; Hypogonadism; Hypothalamo-Hypophyseal System; Hypothalamus; Infertility, Female; Infertility, Male; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neurons; Oligopeptides; Ovariectomy; Ovulation; Peptide Fragments; Peptides; Phenotype; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Spermatogenesis

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

Reproduction is sensitive to insufficient body energy reserves, especially in females. Metabolic regulation of the male reproductive axis is less obvious, and the impact of conditions of persistent energy excess has received moderate attention. Yet, the escalating prevalence of obesity and the clinical evidence of its deleterious effects on male fertility have raised considerable concerns. We report here phenotypic and mechanistic studies of the reproductive impact of postnatal nutritional manipulations (mainly overnutrition) coupled to a high-fat diet (HFD) after weaning. Metabolic and hormonal analyses in young (4 months old) and middle-aged (10 months old) animals revealed that HFD caused profound metabolic perturbations, including glucose intolerance, which were worsened by precedent postnatal overfeeding; these were detectable already in young males but aggravated in 10-month-old rats. Impairment of reproductive parameters took place progressively, and HFD alone was sufficient to explain most of these alterations, regardless of postnatal under- or overnutrition. In young males, testosterone (T) levels and steroidogenic enzyme expression were suppressed by HFD, without compensatory increases of LH levels, which were in fact partially inhibited in heavier males. In addition, obese males displayed suppressed hypothalamic Kiss1 expression despite low T, and HFD inhibited LH responses to kisspeptin. Overweight anticipated some of the neuroendocrine effects of aging, such as the suppression of hypothalamic Kiss1 expression and the decline in serum T and LH levels. Nonetheless, HFD per se caused a detectable worsening of key reproductive indices in middle-aged males, such as basal LH and FSH levels as well as LH responses to kisspeptin. Our study demonstrates that nutritional stress, especially HFD, has a profound deleterious impact on metabolic and gonadotropic function as well as on the Kiss1 system and precipitates neuroendocrine reproductive senescence in the male.

Topics: Animals; Body Weight; Diet, High-Fat; Gene Expression Regulation; Glucose Tolerance Test; Hypogonadism; Hypothalamus; In Situ Hybridization; Kisspeptins; Luteinizing Hormone; Male; Neurosecretory Systems; Obesity; Phenotype; Rats; Rats, Wistar; Reproduction; Sex Factors; Testosterone; Time Factors

Premature ovarian failure (POF) affects 1% of women in reproductive age, but its etiology remains uncertain. Whereas kisspeptins, the products of Kiss1 that act via Kiss1r (aka, Gpr54), are known to operate at the hypothalamus to control GnRH/gonadotropin secretion, additional actions at other reproductive organs, including the ovary, have been proposed. Yet, their physiological relevance is still unclear. We present here a series of studies in Kiss1r haplo-insufficient and null mice suggesting a direct role of kisspeptin signaling in the ovary, the defect of which precipitates a state of primary POF. Kiss1r hypomorph mice displayed a premature decline in ovulatory rate, followed by progressive loss of antral follicles, oocyte loss, and a reduction in all categories of preantral follicles. These alterations were accompanied by reduced fertility. Because of this precocious ovarian ageing, mice more than 48 weeks of age showed atrophic ovaries, lacking growing follicles and corpora lutea. This phenomenon was associated with a drop in ovarian Kiss1r mRNA expression, but took place in the absence of a decrease in circulating gonadotropins. In fact, FSH levels increased in aged hypomorph animals, reflecting loss of follicular function. In turn, Kiss1r-null mice, which do not spontaneously ovulate and have arrested follicular development, failed to show normal ovulatory responses to standard gonadotropin priming and required GnRH prestimulation during 1 week in order to display gonadotropin-induced ovulation. Yet, the magnitude of such ovulatory responses was approximately half of that seen in control immature wild-type animals. Altogether, our data are the first to demonstrate that Kiss1r haplo-insufficiency induces a state of POF, which is not attributable to defective gonadotropin secretion. We also show that the failure of follicular development and ovulation linked to the absence of Kiss1r cannot be fully rescued by (even extended) gonadotropin replacement. These findings suggest a direct ovarian role of kisspeptin signaling, the perturbation of which may contribute to the pathogenesis of POF.

Topics: Animals; Female; Gonadotropins; Hypogonadism; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Ovary; Ovulation; Phenotype; Primary Ovarian Insufficiency; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1

Idiopathic hypogonadotropic hypogonadism (IHH) results from defective synthesis, secretion, or action of GnRH. Kisspeptin is a potent stimulus for GnRH secretion.. We probed the functional capacity of the GnRH neuronal network in patients with IHH.. Eleven subjects with congenital IHH (9 men and 2 women) and one male subject who underwent reversal of IHH were studied. Six of the twelve subjects had an identified genetic cause of their IHH: KAL1 (n = 1), FGFR1 (n = 3), PROKR2 (n = 1), GNRHR (n = 1).. Subjects underwent q10 min blood sampling to measure GnRH-induced LH secretion at baseline and in response to intravenous boluses of kisspeptin (0.24 nmol/kg) and GnRH (75 ng/kg) both pre- and post-six days of treatment with exogenous GnRH (25 ng/kg sc every 2 h).. All subjects with abiding IHH failed to demonstrate a GnRH-induced LH response to exogenous kisspeptin. In contrast, the subject who achieved reversal of his hypogonadotropism demonstrated a robust response to kisspeptin.. The functional capacity of the GnRH neuronal network in IHH patients is impaired, as evidenced by their inability to respond to the same dose of kisspeptin that effects a robust GnRH-induced LH response in healthy men and luteal-phase women. This impairment is observed across a range of genotypes, suggesting that it reflects a fundamental property of GnRH neuronal networks that have not been properly engaged during pubertal development. In contrast, a patient who had experienced reversal of his hypogonadotropism responded to exogenous kisspeptin.

Topics: Adult; Extracellular Matrix Proteins; Female; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Middle Aged; Nerve Net; Nerve Tissue Proteins; Neurons; Receptors, LHRH; Young Adult

The hypothalamic hormone kisspeptin (metastin) regulates human reproduction by modulating gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is detected in peripheral blood, although GnRH is not. In this study, we measured plasma kisspeptin levels in four male cases with hypogonadism and seven normal male controls using enzyme immunoassay (EIA) to elucidate the clinical implications of kisspeptin levels in male hypogonadism. The results showed a variety of plasma kisspeptin levels: 6.0 fmol/mL in a male with isolated hypogonadotropic hypogonadism (IHH), 43.2 fmol/mL in a male with Kallmann's syndrome, 40.7 fmol/mL in a male with azoospermia, 323.2 fmol/mL in a male with hypergonadotropic hypogonadism, and 12.3 ± 2.5 fmol/mL (mean ± SD) in seven normal controls. Except for the case with IHH, the plasma kisspetin levels were elevated in the three cases with Kallmann's syndrome, azoospermia, and hypergonadotropic hypogonadism. The reason why the three cases had high values was their lesions were downstream of the kisspeptin neuron in the hypothalamic-pituitary-gonadal axis, suggesting that elevated kisspeptin levels were implicated in hypothalamic kisspeptin secretion under decreased negative feedback of gonadal steroids. The result that the plasma kisspeptin levels were decreased by gonadotropin therapy in the case with Kallmann's syndrome supported this hypothesis. In conclusion, to measure plasma kisspeptin levels could be useful for better understanding of male hypogonadism.

Topics: Adult; Azoospermia; Humans; Hypogonadism; Kallmann Syndrome; Kisspeptins; Male

Kisspeptin, encoded by Kiss1, stimulates reproduction. In rodents, one Kiss1 population resides in the hypothalamic anterior ventral periventricular nucleus and neighboring rostral periventricular nucleus (AVPV/PeN). AVPV/PeN Kiss1 neurons are sexually dimorphic (greater in females), yet the mechanisms regulating their development and sexual differentiation remain poorly understood. Neonatal estradiol (E₂) normally defeminizes AVPV/PeN kisspeptin neurons, but emerging evidence suggests that developmental E₂ may also influence feminization of kisspeptin, although exactly when in development this process occurs is unknown. In addition, the obligatory role of GnRH signaling in governing sexual differentiation of Kiss1 or other sexually dimorphic traits remains untested. Here, we assessed whether AVPV/PeN Kiss1 expression is permanently impaired in adult hpg (no GnRH or E₂) or C57BL6 mice under different E₂ removal or replacement paradigms. We determined that 1) despite lacking GnRH signaling in development, marked sexual differentiation of Kiss1 still occurs in hpg mice; 2) adult hpg females, who lack lifetime GnRH and E₂ exposure, have reduced AVPV/PeN Kiss1 expression compared to wild-type females, even after chronic adulthood E₂ treatment; 3) E₂ exposure to hpg females during the pubertal period does not rescue their submaximal adult Kiss1 levels; and 4) in C57BL6 females, removal of ovarian E2 before the pubertal or juvenile periods does not impair feminization and maximal adult AVPV/PeN Kiss1 expression nor the ability to generate LH surges, indicating that puberty is not a critical period for Kiss1 development. Thus, sexual differentiation still occurs without GnRH, but GnRH or downstream E₂ signaling is needed sometime before juvenile development for complete feminization and maximal Kiss1 expression in adult females.

Topics: Animals; Anterior Thalamic Nuclei; Estradiol; Estrogen Receptor alpha; Estrogen Replacement Therapy; Estrogens; Female; Gonadotropin-Releasing Hormone; Hypogonadism; Intralaminar Thalamic Nuclei; Kisspeptins; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nerve Tissue Proteins; Neurons; Ovariectomy; Sex Differentiation; Sexual Development; Signal Transduction; Thalamic Nuclei; Up-Regulation

Polycystic ovary syndrome is a common endocrine disorder in females of reproductive age and is believed to have a developmental origin in which gestational androgenization programs reproductive and metabolic abnormalities in offspring. During gestation, both male and female fetuses are exposed to potential androgen excess. In this study, we determined the consequences of developmental androgenization in male mice exposed to neonatal testosterone (NTM). Adult NTM displayed hypogonadotropic hypogonadism with decreased serum testosterone and gonadotropin concentrations. Hypothalamic KiSS1 neurons are believed to be critical to the onset of puberty and are the target of leptin. Adult NTM exhibited lower hypothalamic Kiss1 expression and a failure of leptin to upregulate Kiss1 expression. NTM displayed an early reduction in lean mass, decreased locomotor activity, and decreased energy expenditure. They displayed a delayed increase in subcutaneous white adipose tissue amounts. Thus, excessive neonatal androgenization disrupts reproduction and energy homeostasis and predisposes to hypogonadism and obesity in adult male mice.

Topics: Adiposity; Androgens; Animals; Animals, Newborn; Behavior, Animal; Energy Metabolism; Environmental Pollutants; Gonadotropins; Hypogonadism; Hypothalamus; Infertility, Male; Kisspeptins; Male; Mice; Motor Activity; Nerve Tissue Proteins; Neurons; Obesity; Subcutaneous Fat, Abdominal; Testosterone

KISS1R mutations have been reported in few patients with normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110).. To describe in detail nCHH patients with biallelic KISS1R mutations belonging to 2 unrelated families, and to functionally characterize a novel KISS1R mutation.. An original mutant, p.Tyr313His, was found in the homozygous state in 3 affected kindred (2 females and 1 male) from a consanguineous Portuguese family. This mutation, located in the seventh transmembrane domain, affects a highly conserved amino acid, perturbs the conformation of the transmembrane segment, and impairs MAP kinase signaling and intracellular calcium release. In the second family, a French Caucasian male patient with nCHH was found to carry two recurrent mutations in the compound heterozygous state (p.Leu102Pro/Stop399Arg). In this man, pulsatile GnRH (Gonadotropin Releasing Hormone) administration restored pulsatile LH (Luteinizing Hormone) secretion and testicular hormone secretion. Later, long-term combined gonadotropin therapy induced spermatogenesis, enabling 3 successive pregnancies that resulted in 2 miscarriages and the birth of a healthy boy.. We show that a novel loss-of-function mutation (p.Tyr313His) in the KISS1R gene can cause familial nCHH, revealing the crucial role of this amino acid in KISS1R function. The observed restoration of gonadotropin secretion by exogenous GnRH administration further supports, in humans, the hypothalamic origin of the gonadotropin deficiency in this genetic form of nCHH.

Topics: Alleles; Amino Acid Sequence; Animals; Blotting, Western; Calcium; Chlorocebus aethiops; COS Cells; DNA Mutational Analysis; Extracellular Signal-Regulated MAP Kinases; Family Health; Female; Genetic Predisposition to Disease; HEK293 Cells; Humans; Hypogonadism; Kisspeptins; Male; Models, Molecular; Molecular Sequence Data; Mutation; Pedigree; Phosphorylation; Protein Conformation; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sequence Homology, Amino Acid

Kisspeptins (Kp), products of the Kiss1 gene that act via Gpr54 to potently stimulate GnRH secretion, operate as mediators of other regulatory signals of the gonadotropic axis. Mouse models of Gpr54 and/or Kiss1 inactivation have been used to address the contribution of Kp in the central control of gonadotropin secretion; yet, phenotypic and hormonal differences have been detected among the transgenic lines available. We report here a series of neuroendocrine analyses in male mice of a novel Gpr54 knockout (KO) model, generated by heterozygous crossing of a loxP-Gpr54/Protamine-Cre double mutant line. Gpr54-null males showed severe hypogonadotropic hypogonadism but retained robust responsiveness to GnRH. Gonadotropic responses to the agonist of ionotropic glutamate receptors, N-methyl-d-aspartate, were attenuated, but persisted, in Gpr54-null mice. In contrast, LH secretion after activation of metabotropic glutamate receptors was totally preserved in the absence of Gpr54 signaling. Detectable, albeit reduced, LH responses were also observed in Gpr54 KO mice after intracerebroventricular administration of galanin-like peptide or RF9, putative antagonist of neuropeptide FF receptors for the mammalian ortholog of gonadotropin-inhibiting hormone. In contrast, the stimulatory effect of senktide, agonist of neurokinin B (NKB; cotransmitter of Kiss1 neurons), was totally abrogated in Gpr54 KO males. Lack of Kp signaling also eliminated feedback LH responses to testosterone withdrawal. However, residual but sustained increases of FSH were detected in gonadectomized Gpr54 KO males, in which testosterone replacement failed to fully suppress circulating FSH levels. In sum, our study provides novel evidence for the relative importance of Kp-dependent vs. -independent actions of several key regulators of GnRH secretion, such as glutamate, galanin-like peptide, and testosterone. In addition, our data document for the first time the indispensable role of Kp signaling in mediating the stimulatory effects of NKB on LH secretion, thus supporting the hypothesis that NKB actions on GnRH neurons are indirectly mediated via its ability to regulate Kiss1 neuronal output.

Topics: Adamantane; Animals; Dipeptides; Follicle Stimulating Hormone; Galanin-Like Peptide; Glutamic Acid; Gonadotropin-Releasing Hormone; Gonadotropins; Hypogonadism; Kisspeptins; Luteinizing Hormone; Male; Mice; Mice, Knockout; Models, Neurological; Naltrexone; Neurokinin B; Peptide Fragments; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, N-Methyl-D-Aspartate; Receptors, Neuropeptide; Signal Transduction; Substance P; Testosterone

Gonadotropin-releasing hormone (GnRH) is the central regulator of gonadotropins, which stimulate gonadal function. Hypothalamic neurons that produce kisspeptin and neurokinin B stimulate GnRH release. Inactivating mutations in the genes encoding the human kisspeptin receptor (KISS1R, formerly called GPR54), neurokinin B (TAC3), and the neurokinin B receptor (TACR3) result in pubertal failure. However, human kisspeptin loss-of-function mutations have not been described, and contradictory findings have been reported in Kiss1-knockout mice. We describe an inactivating mutation in KISS1 in a large consanguineous family that results in failure of pubertal progression, indicating that functional kisspeptin is important for puberty and reproduction in humans. (Funded by the Scientific and Technological Research Council of Turkey [TÜBİTAK] and others.).

Topics: Adolescent; Adult; Child; Consanguinity; Female; Genes, Recessive; Genotyping Techniques; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Male; Mutation; Pedigree; Puberty; Sequence Analysis, DNA

Normosmic idiopathic hypogonadotropic hypogonadism (nIHH) is characterized by failure of initiation or maintenance of puberty due to insufficient gonadotropin release, which is not associated with anosmia/hyposmia. The objective of this study was to determine the distribution of causative mutations in a hereditary form of nIHH.. In this prospective collaborative study, 22 families with more than one affected individual (i.e. multiplex families) with nIHH were recruited and screened for genes known or suspected to be strong candidates for nIHH.. Mutations were identified in five genes (GNRHR, TACR3, TAC3, KISS1R, and KISS1) in 77% of families with autosomal recessively inherited nIHH. GNRHR and TACR3 mutations were the most common two causative mutations occurring with about equal frequency.. Mutations in these five genes account for about three quarters of the causative mutations in nIHH families with more than one affected individual. This frequency is significantly greater than the previously reported rates in all inclusive (familial plus sporadic) cohorts. GNRHR and TACR3 should be the first two genes to be screened for diagnostic purposes. Identification of causative mutations in the remaining families will shed light on the regulation of puberty.

Topics: Adolescent; Adult; Cohort Studies; Family Health; Genetic Association Studies; Humans; Hypogonadism; Infant; Kisspeptins; Male; Mutation; Neurokinin B; Prospective Studies; Protein Isoforms; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, LHRH; Receptors, Neurokinin-3; Tachykinins; Turkey; Young Adult

Mutations in the GnRH receptor gene (GNRHR) can result in hypogonadotropic hypogonadism in humans. Unlike most mammals, mice lack a second form of GnRH (GnRH2) and a type 2 GnRH receptor. To determine whether the GnRH receptor is critical at all stages of reproduction and whether this receptor has additional physiological functions in developing and adult mice, we have generated mice from an embryonic stem cell line containing a retroviral vector with multiple stop codons inserted into intron 1 of the Gnrhr gene. This gene trap insertion resulted in the disruption of exon 2 and exon 3 of the Gnrhr gene. The insertion also contained a lacZ gene that was used as a reporter for GnRH receptor expression in these mice. This model has a similar phenotype to the clinical syndrome of hypogonadotropic hypogonadism. Null Gnrhr mice had small sexual organs, low levels of FSH, LH, and steroid hormones, failure of sexual maturation, infertility, and inability to respond to exogenous GnRH. However, the defective GnRH receptor did not prevent morula/blastocyst development, implantation, masculinization of fetal male mice, or maintenance of early pregnancy. The phenotype of this null Gnrhr mouse was more severe than models in the literature, including the N-ethyl-N-nitrosourea-induced Gnrhr mutant, the kisspeptin (Kiss1) knockout, and the kisspeptin receptor (Gpr54) knockout. In terms of gonadal morphology, adult gene trap-Gnrhr null mice demonstrate a complete cessation of reproduction and serve as an important model for understanding GnRH/GnRHR physiology.

Topics: Alkylating Agents; Animals; Ethylnitrosourea; Female; Genes, Reporter; Gonadotropin-Releasing Hormone; Hypogonadism; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Ovary; Phenotype; Pregnancy; Proteins; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, LHRH; Testis

Kisspeptin, encoded by the KISS1 gene, is a key stimulatory factor of GnRH secretion and puberty onset. Inactivating mutations of its receptor (KISS1R) cause isolated hypogonadotropic hypogonadism (IHH). A unique KISS1R-activating mutation was described in central precocious puberty (CPP).. Our objective was to investigate KISS1 mutations in patients with idiopathic CPP and normosmic IHH.. Eighty-three children with CPP (77 girls) and 61 patients with IHH (40 men) were studied. The control group consisted of 200 individuals with normal pubertal development.. The promoter region and the three exons of KISS1 were amplified and sequenced. Cells expressing KISS1R were stimulated with synthetic human wild-type or mutant kisspeptin-54 (kp54), and inositol phosphate accumulation was measured. In a second set of experiments, kp54 was preincubated in human serum before stimulation of the cells.. Two novel KISS1 missense mutations, p.P74S and p.H90D, were identified in three unrelated children with idiopathic CPP. Both mutations were absent in 400 control alleles. The p.P74S mutation was identified in the heterozygous state in a boy who developed CPP at 1 yr of age. The p.H90D mutation was identified in the homozygous state in two unrelated girls with CPP. In vitro studies revealed that the capacity of the P74S and H90D mutants to stimulate IP production was similar to the wild type. After preincubation of wild-type and mutant kp54 in human serum, the capacity to stimulate signal transduction was significantly greater for P74S compared with the wild type, suggesting that the p.P74S variant is more stable. Only polymorphisms were found in the IHH group.. Two KISS1 mutations were identified in unrelated patients with idiopathic CPP. The p.P74S variant was associated with higher kisspeptin resistance to degradation in comparison with the wild type, suggesting a role for this mutation in the precocious puberty phenotype.

Topics: Exons; Female; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Infant; Kisspeptins; Male; Mutation; Penis; Puberty; Puberty, Precocious; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Tumor Suppressor Proteins

Severe inflammatory challenges are frequently coupled to decreased food intake and disruption of reproductive function, the latter via deregulation of different signaling pathways that impinge onto GnRH neurons. Recently, the hypothalamic Kiss1 system, a major gatekeeper of GnRH function, was suggested as potential target for transmitting immune-mediated repression of the gonadotropic axis during acute inflammation, and yet key facets of such a phenomenon remain ill defined. Using lipopolysaccharide S (LPS)-treated male rats as model of inflammation, we document herein the pattern of hypothalamic kisspeptin immunoreactivity (IR) and hormonal responses to kisspeptin during the acute inflammatory phase. LPS injections induced a dramatic but transient drop of serum LH and testosterone levels. Suppression of gonadotropic function was associated with a significant decrease in kisspeptin-IR in the arcuate nucleus (ARC) that was not observed under conditions of metabolic stress induced by 48-h fasting. In addition, absolute responses to kisspeptin-10 (Kp-10), in terms of LH and testosterone secretion, were significantly attenuated in LPS-treated males that also displayed a decrease in food intake and body weight. Yet pair-fed males did not show similar alterations in LH and testosterone secretory responses to Kp-10, whose magnitude was preserved, if not augmented, during food restriction. In summary, our data document the impact of acute inflammation on kisspeptin content at the ARC as key center for the neuroendocrine control of reproduction. Our results also suggest that suppressed gonadotropic function following inflammatory challenges might involve a reduction in absolute responsiveness to kisspeptin that is independent of the anorectic effects of inflammation.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Area Under Curve; Eating; Hypogonadism; Immunohistochemistry; Inflammation; Kisspeptins; Luteinizing Hormone; Male; Oligopeptides; Rats; Rats, Wistar; Testosterone

Kisspeptin is a potent activator of GnRH-induced gonadotropin secretion and is a proposed central regulator of pubertal onset. In mice, there is a neuroanatomical separation of two discrete kisspeptin neuronal populations, which are sexually dimorphic and are believed to make distinct contributions to reproductive physiology. Within these kisspeptin neuron populations, Kiss1 expression is directly regulated by sex hormones, thereby confounding the roles of sex differences and early activational events that drive the establishment of kisspeptin neurons. In order to better understand sex steroid hormone-dependent and -independent effects on the maturation of kisspeptin neurons, hypogonadal (hpg) mice deficient in GnRH and its downstream effectors were used to determine changes in the developmental kisspeptin expression. In hpg mice, sex differences in Kiss1 mRNA levels and kisspeptin immunoreactivity, typically present at 30 days of age, were absent in the anteroventral periventricular nucleus (AVPV). Although immunoreactive kisspeptin increased from 10 to 30 days of age to levels intermediate between wild type (WT) females and males, corresponding increases in Kiss1 mRNA were not detected. In contrast, the hpg arcuate nucleus (ARC) demonstrated a 10-fold increase in Kiss1 mRNA between 10 and 30 days in both females and males, suggesting that the ARC is a significant center for sex steroid-independent pubertal kisspeptin expression. Interestingly, the normal positive feedback response of AVPV kisspeptin neurons to estrogen observed in WT mice was lost in hpg females, suggesting that exposure to reproductive hormones during development may contribute to the establishment of the ovulatory gonadotropin surge mechanism. Overall, these studies suggest that the onset of pubertal kisspeptin expression is not dependent on reproductive hormones, but that gonadal sex steroids critically shape the hypothalamic kisspeptin neuronal subpopulations to make distinct contributions to the activation and control of the reproductive hormone cascade at the time of puberty.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Female; Gonadotropin-Releasing Hormone; Hypogonadism; Immunohistochemistry; In Situ Hybridization; Kisspeptins; Male; Mice; Reverse Transcriptase Polymerase Chain Reaction; Sex Characteristics; Tumor Suppressor Proteins

The reproductive phenotypes of nearly two dozen patients with mutations in GPR54 have been reported, as have the phenotypes of four mouse lines mutant for Gpr54 and two lines mutant for Kiss1. These phenotypes demonstrate that kisspeptin/Gpr54 function is required at all phases of the life cycle when the secretion of gonadotropin-releasing hormone (GnRH) is robust. Furthermore, there is phenotypic variability ranging from severe hypogonadism to partial sexual development. Collectively, these findings suggest that kisspeptin and Gpr54 serve as an essential conduit for relaying developmental information to the GnRH neuron.

Topics: Adolescent; Adult; Animals; Child; Female; Fertility; Humans; Hypogonadism; Kisspeptins; Male; Mice; Mice, Knockout; Mutation; Phenotype; Puberty; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reproduction; Tumor Suppressor Proteins; Young Adult

The timely secretion of gonadal sex steroids is essential for the initiation of puberty, the postpubertal maintenance of secondary sexual characteristics and the normal perinatal development of male external genitalia. Normal gonadal steroid production requires the actions of the pituitary-derived gonadotropins, luteinizing hormone and follicle-stimulating hormone. We report four human pedigrees with severe congenital gonadotropin deficiency and pubertal failure in which all affected individuals are homozygous for loss-of-function mutations in TAC3 (encoding Neurokinin B) or its receptor TACR3 (encoding NK3R). Neurokinin B, a member of the substance P-related tachykinin family, is known to be highly expressed in hypothalamic neurons that also express kisspeptin, a recently identified regulator of gonadotropin-releasing hormone secretion. These findings implicate Neurokinin B as a critical central regulator of human gonadal function and suggest new approaches to the pharmacological control of human reproduction and sex hormone-related diseases.

Topics: Amino Acid Sequence; Chromosomes, Human, Pair 4; DNA Mutational Analysis; Family; Gonads; Humans; Hypogonadism; Kisspeptins; Models, Biological; Mutation; Neurokinin B; Neurons; Pedigree; Receptors, Neurokinin-3; Reproduction; Sequence Homology, Amino Acid; Tumor Suppressor Proteins

Topics: Gonads; Humans; Hypogonadism; Hypothalamo-Hypophyseal System; Kisspeptins; Mutation; Neurokinin B; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Topics: Animals; Feedback, Physiological; Forecasting; Gonadal Steroid Hormones; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Mice; Mice, Knockout; Preoptic Area; Puberty; Reproduction; Tumor Suppressor Proteins

One of the challenges of gene targeting is to achieve regulated transgene expression in specific target cells. The hypogonadal (hpg) mice are genetically deficient in hypothalamic gonadotropin-releasing hormone (GnRH) production due to a deletion in the GnRH gene, resulting in hypogonadotropic hypogonadism. Here we show an improvement in reproductive parameters of adult female homozygous hpg mice by direct infusion into the hypothalamic preoptic area (POA) of a herpes simplex virus (HSV)-based amplicon vector containing a 13.5 kb genomic fragment encoding the GnRH gene together with its cognate promoter and regulatory elements. Following vector injection, GnRH-expressing neurons were detected in the POA, and pituitary and plasma gonadotropin levels as well as ovarian and uterine weights increased. In addition, a subset of injected hpg mice demonstrated cyclic estrous changes, consistent with regulated control of GnRH production. Administration of kisspeptin-10 resulted in an increase in plasma luteinizing hormone levels, further supporting appropriate regulation of the introduced GnRH transgene. These findings indicate that delivery of the GnRH gene resulted in selective neuronal expression of GnRH and regulated hypothalamic GnRH release. To our knowledge, this is the first example of the correct targeting of a gene under its cognate promoter to neurons resulting in selective and regulated synthesis of a biologically active peptide, and thus may have a wide range of applications in the treatment of human disorders.

Topics: Animals; Female; Follicle Stimulating Hormone; Gene Expression Regulation; Gene Targeting; Genetic Engineering; Genetic Therapy; Genetic Vectors; Gonadotropin-Releasing Hormone; Green Fluorescent Proteins; Herpesvirus 1, Human; Hypogonadism; Hypothalamus; Immunohistochemistry; Kisspeptins; Luteinizing Hormone; Mice; Mice, Mutant Strains; Neurons; Oligopeptides; Preoptic Area; Promoter Regions, Genetic; Transgenes

The G protein-coupled receptor GPR54 (AXOR12, OT7T175) is central to acquisition of reproductive competency in mammals. Peptide ligands (kisspeptins) for this receptor are encoded by the Kiss1 gene, and administration of exogenous kisspeptins stimulates hypothalamic gonadotropin-releasing hormone (GnRH) release in several species, including humans. To establish that kisspeptins are the authentic agonists of GPR54 in vivo and to determine whether these ligands have additional physiological functions we have generated mice with a targeted disruption of the Kiss1 gene. Kiss1-null mice are viable and healthy with no apparent abnormalities but fail to undergo sexual maturation. Mutant female mice do not progress through the estrous cycle, have thread-like uteri and small ovaries, and do not produce mature Graffian follicles. Mutant males have small testes, and spermatogenesis arrests mainly at the early haploid spermatid stage. Both sexes have low circulating gonadotropin (luteinizing hormone and follicle-stimulating hormone) and sex steroid (beta-estradiol or testosterone) hormone levels. Migration of GnRH neurons into the hypothalamus appears normal with appropriate axonal connections to the median eminence and total GnRH content. The hypothalamic-pituitary axis is functional in these mice as shown by robust luteinizing hormone secretion after peripheral administration of kisspeptin. The virtually identical phenotype of Gpr54- and Kiss1-null mice provides direct proof that kisspeptins are the true physiological ligand for the GPR54 receptor in vivo. Kiss1 also does not seem to play a vital role in any other physiological processes other than activation of the hypothalamic-pituitary-gonadal axis, and loss of Kiss1 cannot be overcome by compensatory mechanisms.

Topics: Aging; Animals; Female; Gene Targeting; Gonadotropin-Releasing Hormone; Hypogonadism; Kisspeptins; Male; Mice; Mice, Mutant Strains; Proteins

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

Topics: Administration, Cutaneous; Estradiol; Female; Humans; Hypogonadism; Kallmann Syndrome; Kisspeptins; Puberty; Tumor Suppressor Proteins; Turner Syndrome

Topics: Animals; Brain; Circadian Rhythm; Female; Gonadotropin-Releasing Hormone; Humans; Hypogonadism; Kisspeptins; Leptin; Male; Mutation; Neurons; Proteins; Puberty; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, Leptin; Receptors, Neuropeptide; Reproduction; Signal Transduction; Tumor Suppressor Proteins

GPR54 is a G-protein-coupled receptor that displays a high percentage of identity in the transmembrane domains with the galanin receptors. The ligand for GPR54 has been identified as a peptide derived from the KiSS-1 gene. KiSS-1 has been shown to have anti-metastatic effects, suggesting that KiSS-1 or its receptor represents a potential therapeutic target. To further our understanding of the physiological function of this receptor, we have generated a mutant mouse line with a targeted disruption of the GPR54 receptor (GPR54 -/-). The analysis of the GPR54 mutant mice revealed developmental abnormalities of both male and female genitalia and histopathological changes in tissues which normally contain sexually dimorphic features. These data suggest a role for GPR54/KiSS-1 in normal sexual development, and indicate that study of the GPR54 mutant mice may provide valuable insights into human reproductive syndromes.

Topics: Animals; Female; Genitalia; Hypogonadism; Kisspeptins; Male; Mice; Mice, Knockout; Mutation; Organ Specificity; Phenotype; Proteins; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, Neuropeptide; Reproduction; Sexual Maturation; Tissue Distribution