Investigating the detection of the novel doping­relevant peptide kisspeptin­10 in urine using liquid chromatography high­resolution mass spectrometry.

Kisspeptin-10 is a peptide hormone capable of increasing circulating follicle-stimulating hormone, luteinizing hormone and testosterone levels in humans. Clinically, these effects suggest its use as a treatment for infertility. However, its testosterone-increasing effect indicates potential misuse in sports. As such, it is included in the 2024 World Anti-Doping Agency Prohibited List. This work describes the successful validation of an initial testing procedure (screening) and a confirmation procedure for kisspeptin-10 in urine using liquid chromatography-mass spectrometry. Additionally, kisspeptin-10 was incubated in human serum to mimic endogenous metabolism to improve method sensitivity, as previous research had demonstrated a rapid elimination time of only 30 min after injection (in rats). Four metabolites, corresponding to peptide fragments y9, y8, y7 and y5, were found and added to the ITP in full scan mode. A degradation product discovered during early experimentation was found to probably be caused by oxidation of the tryptophan residue into a kynurenine residue. Further research should elucidate the kinetic parameters of the reaction to improve product stability. Using the validated confirmation procedure, a black-market vial of kisspeptin-10 was analysed. The product contained no unexpected impurities, although it appeared to have undergone more degradation than the purchased reference standard.

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

STUDY QUESTION: Do hyperactive kisspeptin neurons contribute to abnormally high LH secretion and downstream hyperandrogenemia in polycystic ovary syndrome (PCOS)-like conditions and can inhibition of kisspeptin neurons rescue such endocrine impairments? SUMMARY ANSWER: Targeted inhibition of endogenous kisspeptin neuron activity in a mouse model of PCOS reduced the abnormally hyperactive LH pulse secretion and hyperandrogenemia to healthy control levels. WHAT IS KNOWN ALREADY: PCOS is a reproductive disorder characterized by hyperandrogenemia, anovulation, and/or polycystic ovaries, along with a hallmark feature of abnormal LH hyper-pulsatility, but the mechanisms underlying the endocrine impairments remain unclear. A chronic letrozole (LET; aromatase inhibitor) mouse model recapitulates PCOS phenotypes, including polycystic ovaries, anovulation, high testosterone, and hyperactive LH pulses. LET PCOS-like females also have increased hypothalamic kisspeptin neuronal activation which may drive their hyperactive LH secretion and hyperandrogenemia, but this has not been tested. STUDY DESIGN, SIZE, DURATION: Transgenic KissCRE+/hM4Di female mice or littermates Cre- controls were treated with placebo, or chronic LET (50 µg/day) to induce a PCOS-like phenotype, followed by acute (once) or chronic (2 weeks) clozapine-N-oxide (CNO) exposure to chemogenetically inhibit kisspeptin cells (n = 6 to 10 mice/group). PARTICIPANTS/MATERIALS, SETTING, METHODS: Key endocrine measures, including in vivo LH pulse secretion patterns and circulating testosterone levels, were assessed before and after selective kisspeptin neuron inhibition and compared between PCOS groups and healthy controls. Alterations in body weights were measured and pituitary and ovarian gene expression was determined by qRT-PCR. MAIN RESULTS AND THE ROLE OF CHANCE: Acute targeted inhibition of kisspeptin neurons in PCOS mice successfully lowered the abnormally hyperactive LH pulse secretion (P < 0.05). Likewise, chronic selective suppression of kisspeptin neuron activity reversed the previously high LH and testosterone levels (P < 0.05) down to healthy control levels and rescued reproductive gene expression (P < 0. 05). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Ovarian morphology was not assessed in this study. Additionally, mouse models can offer mechanistic insights into neuroendocrine processes in PCOS-like conditions but may not perfectly mirror PCOS in women. WIDER IMPLICATIONS OF THE FINDINGS: These data support the hypothesis that overactive kisspeptin neurons can drive neuroendocrine PCOS-like impairments, and this may occur in PCOS women. Our findings complement recent clinical investigations using NKB receptor antagonists to lower LH in PCOS women and suggest that pharmacological dose-dependent modulation of kisspeptin neuron activity may be a valuable future therapeutic target to clinically treat hyperandrogenism and lower elevated LH in PCOS women. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by NIH grants R01 HD111650, R01 HD090161, R01 HD100580, P50 HD012303, R01 AG078185, and NIH R24 HD102061, and a pilot project award from the British Society for Neuroendocrinology. There are no competing interests.

[Notch1/Akt/Foxo1 Pathway Regulated by Kisspeptin Is Involved in Endometrial Decidualization in Patients With Recurrent Spontaneous Abortion]. / kisspeptin调控Notch1/Akt/Foxo1é€šè·¯å‚ä¸Žå¤å‘æ€§æµäº§æ‚£è€ å­å®«å† è†œèœ•è†œåŒ–.

Objective: Kisspeptin, a protein encoded by the KISS1 gene, functions as an essential factor in suppressing tumor growth. The intricate orchestration of cellular processes such as proliferation and differentiation is governed by the Notch1/Akt/Foxo1 signaling pathway, which assumes a central role in maintaining cellular homeostasis. In the specific context of this investigation, the focal point lies in a meticulous exploration of the intricate mechanisms underlying the regulatory effect of kisspeptin on the process of endometrial decidualization. This investigation delves into the interplay between kisspeptin and the Notch1/Akt/Foxo1 signaling pathway, aiming to elucidate its significance in the pathophysiology of recurrent spontaneous abortion (RSA). Methods: We enrolled a cohort comprising 45 individuals diagnosed with RSA, who were admitted to the outpatient clinic of the Reproductive Center at the Second Affiliated Hospital of Soochow University between June 2020 and December 2020. On the other hand, an additional group of 50 women undergoing elective abortion at the outpatient clinic of the Family Planning Department during the same timeframe was also included. To comprehensively assess the molecular landscape, Western blot and RT-qPCR were performed to analyze the expression levels of kisspeptin (and its gene KISS1), IGFBP1 (an established marker of decidualization), Notch1, Akt, and Foxo1 within the decidua. Human endometrial stromal cells (hESC) were given targeted interventions, including treatment with siRNA to disrupt KISS1 or exposure to kisspeptin10 (the bioactive fragment of kisspeptin), and were subsequently designated as the siKP group or the KP10 group, respectively. A control group comprised hESC was transfected with blank siRNA, and cell proliferation was meticulously evaluated with CCK8 assay. Following in vitro induction for decidualization across the three experimental groups, immunofluorescence assay was performed to identify differences in Notch1 expression and decidualization morphology between the siKP and the KP10 groups. Furthermore, RT-qPCR and Western blot were performed to gauge the expression levels of IGFBP1, Notch1, Akt, and Foxo1 across the three cell groups. Subsequently, decidualization was induced in hESC by adding inhibitors targeting Notch1, Akt, and Foxo1. The expression profiles of the aforementioned proteins and genes in the four groups were then examined, with hESC induced for decidualization without adding inhibitors serving as the normal control group. To establish murine models of normal pregnancy (NP) and RSA, CBA/J×BALB/c and CBA/J×DBA/2 mice were used. The mice were respectively labeled as the NP model and RSA model. The experimental groups received intraperitoneal injections of kisspeptin10 and kisspeptin234 (acting as a blocker) and were designated as RSA-KP10 and NP-KP234 groups. On the other hand, the control groups received intraperitoneal injections of normal saline (NS) and were referred to as RSA-NS and NP-NS groups. Each group comprised 6 mice, and uterine tissues from embryos at 9.5 days of gestation were meticulously collected for observation of embryo absorption and examination of the expression of the aforementioned proteins and genes. Results: The analysis revealed that the expression levels of kisspeptin, IGFBP1, Notch1, Akt, and Foxo1 were significantly lower in patients diagnosed with RSA compared to those in women with NP (P<0.01 for kisspeptin and P<0.05 for IGFBP1, Notch1, Akt, and Foxo1). After the introduction of kisspeptin10 to hESC, there was an observed enhancement in decidualization capability. Subsequently, the expression levels of Notch1, Akt, and Foxo1 showed an increase, but they decreased after interference with KISS1. Through immunofluorescence analysis, it was observed that proliferative hESC displayed a slender morphology, but they transitioned to a rounder and larger morphology post-decidualization. Concurrently, the expression of Notch1 increased, suggesting enhanced decidualization upon the administration of kisspeptin10, but the expression decreased after interference with KISS1. Further experimentation involved treating hESC with inhibitors specific to Notch1, Akt, and Foxo1 separately, revealing a regulatory sequence of Notch1/Akt/Foxo1 (P<0.05). In comparison to the NS group, NP mice administered with kisspeptin234 exhibited increased fetal absorption rates (P<0.001) and decreased expression of IGFBP1, Notch1, Akt, and Foxo1 (P<0.05). Conversely, RSA mice administered with kisspeptin10 demonstrated decreased fetal absorption rates (P<0.001) and increased expression levels of the aforementioned molecules (P<0.05). Conclusion: It is suggested that kisspeptin might exert its regulatory influence on the process of decidualization through the modulation of the Notch1/Akt/Foxo1 signaling cascade. A down-regulation of the expression levels of kisspeptin could result in suboptimal decidualization, which in turn might contribute to the development or progression of RSA.

Estradiol elicits distinct firing patterns in arcuate nucleus kisspeptin neurons of females through altering ion channel conductances.

Hypothalamic kisspeptin (Kiss1) neurons are vital for pubertal development and reproduction. Arcuate nucleus Kiss1 (Kiss1ARH) neurons are responsible for the pulsatile release of Gonadotropin-releasing Hormone (GnRH). In females, the behavior of Kiss1ARH neurons, expressing Kiss1, Neurokinin B (NKB), and Dynorphin (Dyn), varies throughout the ovarian cycle. Studies indicate that 17ß-estradiol (E2) reduces peptide expression but increases Vglut2 mRNA and glutamate neurotransmission in these neurons, suggesting a shift from peptidergic to glutamatergic signaling. To investigate this shift, we combined transcriptomics, electrophysiology, and mathematical modeling. Our results demonstrate that E2 treatment upregulates the mRNA expression of voltage-activated calcium channels, elevating the whole-cell calcium current and that contribute to high-frequency burst firing. Additionally, E2 treatment decreased the mRNA levels of Canonical Transient Receptor Potential (TPRC) 5 and G protein-coupled K+ (GIRK) channels. When TRPC5 channels in Kiss1ARH neurons were deleted using CRISPR, the slow excitatory postsynaptic potential (sEPSP) was eliminated. Our data enabled us to formulate a biophysically realistic mathematical model of the Kiss1ARH neuron, suggesting that E2 modifies ionic conductances in Kiss1ARH neurons, enabling the transition from high frequency synchronous firing through NKB-driven activation of TRPC5 channels to a short bursting mode facilitating glutamate release. In a low E2 milieu, synchronous firing of Kiss1ARH neurons drives pulsatile release of GnRH, while the transition to burst firing with high, preovulatory levels of E2 would facilitate the GnRH surge through its glutamatergic synaptic connection to preoptic Kiss1 neurons.

Malnutrition alters protein expression of KNDy neuropeptides in the arcuate nucleus of mature ewes.

The neuropeptides kisspeptin, neurokinin B, and dynorphin A are imperative for the pulsatile secretion of gonadotropin-releasing hormone and luteinizing hormone to ultimately regulate reproductive cyclicity. A population of neurons co-expressing these neuropeptides, KNDy neurons, within the arcuate nucleus of the hypothalamus (ARC) are positioned to integrate energy status from afferent neuronal and glial cells. We hypothesized that KNDy-expressing neurons in the ARC of mature ewes are influenced by energy balance. To test this hypothesis, ovary-intact, mature ewes were fed to lose, maintain, or gain body weight and hypothalamic tissue harvested during the luteal phase of the estrous cycle. Fluorescent, multiplex immunohistochemistry with direct antibody conjugation was employed to identify and quantify neurons expressing a single neuropeptide, as well as for the first time report co-expression of kisspeptin, neurokinin B, and dynorphin A protein in the ARC. Previous reports using this population of ewes demonstrated that concentrations of insulin and leptin differed between ewes fed to achieve different body weights and that ewes fed to gain body weight had increased concentrations of progesterone. Moreover, within this population of ewes tanycyte density and cellular penetration into the ARC was increased in ewes fed to gain body weight. Within the current report we have revealed that the number of neurons in the ARC expressing kisspeptin, neurokinin B, and dynorphin A protein was increased in ewes fed to gain body weight. Moreover, the number of KNDy neurons in the ARC expressing all three neuropeptides within a single neuron was decreased in ewes fed to lose body weight and increased in ewes fed to gain body weight when compared to ewes fed to maintain body weight. The cumulative findings of this experimental model suggest that expression of kisspeptin, neurokinin B, and dynorphin A protein in the ARC during the luteal phase of the estrous cycle are influenced by energy balance-induced alterations in circulating concentrations of progesterone that drive changes in morphology and density of tanycytes to ultimately regulate central perception of global energy status. Moreover, these results demonstrate that changes in KNDy neurons within the ARC occur as an adaptation to energy balance, potentially regulated divergently by metabolic milieu via proopiomelanocortin afferents.

Adipose Kiss1 controls aerobic exercise-related adaptive responses in adipose tissue energy homeostasis.

Kisspeptin signaling regulates energy homeostasis. Adiposity is the principal source and receiver of peripheral Kisspeptin, and adipose Kiss1 metastasis suppressor (Kiss1) gene expression is stimulated by exercise. However, whether the adipose Kiss1 gene regulates energy homeostasis and plays a role in adaptive alterations during prolonged exercise remains unknown. Here, we investigated the role of Kiss1 role in mice and adipose tissues and the adaptive changes it induces after exercise, using adipose-specific Kiss1 knockout (Kiss1adipoq-/-) and adeno-associated virus-induced adipose tissue Kiss1-overexpressing (Kiss1adipoq over) mice. We found that adipose-derived kisspeptin signal regulates lipid and glucose homeostasis to maintain systemic energy homeostasis, but in a sex-dependent manner, with more pronounced metabolic changes in female mice. Kiss1 regulated adaptive alterations of genes and proteins in tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OxPhos) pathways in female gWAT following prolonged aerobic exercise. We could further show that adipose Kiss1 deficiency leads to reduced peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α) protein content of soleus muscle and maximum oxygen uptake (VO2 max) of female mice after prolonged exercise. Therefore, adipose Kisspeptin may be a novel adipokine that increases organ sensitivity to glucose, lipids, and oxygen following exercise.

Developmental exposure to environmentally relevant doses of phthalates alters the neural control of male and female reproduction in mice.

The present study aims to analyze the effects of developmental exposure to phthalates at environmentally relevant doses on the neural control of male and female reproduction. For this purpose, C57Bl/6J mice were exposed to di-(2-ethylexyl) phthalate (DEHP) alone (5 or 50 µg/kg/d), or DEHP (5 µg/kg/d) in a phthalate mixture. Exposure through diet started 6 weeks before the first mating and lasted until weaning of litters from the second gestation (multiparous dams). Analyses of offspring born from multiparous dams exposed to DEHP alone or in a phthalate mixture showed that females experienced a delayed pubertal onset, and as adults they had prolonged estrous cyclicity and reduced Kiss1 expression in the preoptic area and mediobasal hypothalamus. Male littermates showed a reduced anogenital distance and delayed pubertal onset compared with controls. However, in adulthood the weight of androgen-sensitive organs and hypothalamic Kiss1 expression were unaffected, suggesting normal functioning of the male gonadotropic axis. Developmental exposure to DEHP alone or in a phthalate mixture reduced the ability of intact males and ovariectomized and hormonally primed females to attract a sexual partner and to express copulatory behaviors. In addition, females were unable to discriminate between male and female stimuli in the olfactory preference test. Social interaction was also impaired in females, while locomotor activity and anxiety-like behavior in both sexes were unaffected by the treatment. The sexual deficiencies were associated with reduced expression of the androgen receptor in the preoptic area and progesterone receptor in the mediobasal hypothalamus, the key regions involved in male and female sexual behavior, respectively. Thus, the neural structures controlling reproduction are vulnerable to developmental exposure to phthalates at environmentally relevant doses in male and female mice. Adult females had an impaired gonadotropic axis and showed more affected behaviors than adult males.

Dynamics in cortisol levels in Danio rerio fish under the influence of a synthetic analog of kisspeptin 1.

The effect of a synthetic analog of kisspeptin 1, a peptide involved in the regulation of the hypothalamicpituitary- gonadal (HPG) stress axis, on the cortisol level of Danio rerio fish was investigated. Kisspeptin 1 was administered at doses of 2 µg/kg and 8 µg/kg followed by resting for 1 h and 4 h. We found that kisspeptin at doses of 2 µg/kg and 8 µg/kg increased cortisol levels, with a significant spike in cortisol levels at 1 h post-injection.

Chronic inflammation decreases arcuate kisspeptin expression in male sheep.

Lipopolysaccharide (LPS) from Gram-negative bacteria induces an immune response and impairs reproduction through suppression of gonadotropin releasing hormone (GnRH), subsequently luteinizing hormone (LH) secretion. While there is evidence that acute inflammation inhibits kisspeptin, little is known about the impact of chronic inflammation on this key reproductive neuropeptide in livestock species. Thus, we sought to examine a central mechanism whereby LPS suppresses LH secretion in sheep. Twenty wethers were randomly assigned to one of five treatment groups: control (CON; n=4), single acute IV LPS dose (SAD; n=4), daily acute IV LPS dose (DAD; n=4), daily increasing IV LPS dose (DID; n=4), and chronic subcutaneous LPS dose (CSD; n=4). On Days 1 and 7, blood samples were collected every 12 minutes for 360 minutes using jugular venipuncture. Following blood collection on Day 7, all animals were euthanized, brain tissue was perfused with 4% paraformaldehyde, and hypothalamic blocks were removed and processed for immunohistochemistry. On Day 1, LH pulse frequency was significantly lower (p=0.02) in SAD (0.25 ± 0.1 pulses/hour), DAD (0.25 ± 0.1 pulses/hour), DID (0.35 ± 0.1 pulses/hour), and CSD (0.40 ± 0.1 pulses/hour) compared to CON (0.70 ±0.1 pulses/hour). On Day 7, only DID animals (0.35 ± 0.1 pulses/hour) had significantly lower (p=0.049) LH pulse frequency compared to controls (0.85 ± 0.1 pulse/hour). Furthermore, only DID animals (33.3 ± 10.9 cells/section/animal) had significantly fewer (p=0.001) kisspeptin-immunopositive cells compared to controls (82.6 ± 13.6 cells/section/animal). Taken together, we suggest that daily increasing doses of LPS is a powerful inhibitor of kisspeptin neurons in young male sheep and a physiologically relevant model to examine the impact of chronic inflammation on the reproductive axis in livestock.

Modulatory effect of vitamin B6 on sex hormone receptors, thyroid, and kisspeptin/kiss1r system in the uterus of pseudopregnant bitches.

This study evaluated whether the treatment of pseudopregnancy in bitches with vitamin B6 modulates uterine expression of receptors for progesterone (PR), oestrogen (ERα), androgen (AR), thyroid hormone (TRα) and the kisspeptin/Kiss1r system. Eighteen pseudopregnant bitches were treated for 20 days in groups receiving placebo (n = 6); cabergoline (5 µg/kg/day; n = 6); or vitamin B6 (50 mg/kg/day; n = 6). Blood was collected on the 1st day of drug administration and 120 h later to measure serum prolactin (PRL). After treatment, they were ovariohysterectomized and uterine fragments were collected for histomorphometry and immunohistochemical evaluation of PR, ERα, AR, TRα, Kiss1 and Kiss1r. After 120 h of cabergoline or vitamin B6 treatment, PRL levels were reduced in the bitches, confirming the antiprolactinemic effect of these drugs. Furthermore, regardless of treatment, the animals exhibited uterine histomorphometry consistent with dioestrus. The PR showed strong immunostaining in all regions and an increase in scores was observed for this receptor in animals treated with vitamin B6 in deep glands. In contrast, ERα and Kiss1R receptors showed weak to no immunostaining in all uterine regions and no changes between groups. Regarding AR, most animals treated with vitamin B6 showed increased trends in the deep gland and myometrium marking scores. In contrast, in both vitamin B6 and cabergoline treatments, a reduction in TRα marking scores was observed compared to the control group. In addition, on the endometrial surface, a reduction was observed in the marked area of Kiss1 after administration of cabergoline when compared to the pseudopregnant control group. These findings shed valuable insight into the use of vitamin B6 as a drug with actions similar to cabergoline in reducing PRL and uterine modulation in bitches.

Nitric oxide mediated kisspeptin regulation of steroidogenesis and gametogenesis in the catfish, Clarias batrachus.

Nitric oxide (NO) is a gaseous molecule that regulates various reproductive functions. It is a well-recognized regulator of GnRH-FSH/LH-sex steroid secretion in vertebrates including fish. Kisspeptin is a recently discovered neuropeptide which also regulates GnRH secretion. Nitrergic and kisspeptin neurons are reported in close physical contact in the mammalian brain suggesting their interactive role in the release of GnRH. The existence of kisspeptin and NOS is also demonstrated in vertebrate gonads, but information on their reciprocal relation in gonads, if any, is obscure. Therefore, attempts were made to evaluate the functional reciprocal relation between nitric oxide and kisspeptin in the catfish gonads, if any, by administering the nitric oxide synthase (NOS) inhibitor, L-NAME {N(G)-nitro-L-arginine methyl ester}, which reduces NO production, and kisspeptin agonist (KP-10) and assessing their impacts on the expressions of kisspeptin1, different NOS isoforms, NO and steroid production in the gonadal tissue. The results revealed that L-NAME suppressed the expression of kiss1 in gonads of the catfish establishing the role of NO in kisspeptin expression. However, KP-10 increased the expression of all the isoforms of NOSs (iNOS, eNOS, nNOS) and concurrently NO and steroids in the ovary and testis. In vitro studies also indicate that kisspeptin stimulates the production of NO and estradiol and testosterone levels in the gonadal explants and medium. Thus, in vivo results clearly suggest a reciprocal interaction between kisspeptin and NO to regulate the gonadal activity of the catfish. The in vitro findings further substantiate our contention regarding the interactive role of kisspeptin and NO in gonadal steroidogenesis.

Systematic review of hormonal strategies to improve fertility in rams.

Reviewing the current state of knowledge on reproductive performance and productive traits in rams has many advantages. First, the compilation of this information will serve as a literature resource for scientists conducting research around the world and will contribute to the understanding of the data collected and interpreted by researchers on the different hormonal strategies used to improve reproductive performance in rams. Second, it will allow scientists to identify current knowledge gaps and set future research priorities in ram reproduction. Rams play an important role in the global flock economy, but their reproductive analysis has been limited in the use of hormonal technologies to increase the productivity of sheep flocks. In this review, we cite the most important works on six hormones that, in one way or another, modify the hypothalamus-pituitary-gonadal axis, at different doses, in and out of the reproductive season, breeds, application methods, among other factors. The overall aim is to increase the reproductive efficiency of rams in different scenarios and, in some cases, of other species due to the lack of limited information on rams.

Participation of kisspeptin, progesterone, and GnRH receptors on lordosis behavior induced by kisspeptin.

The neuropeptide kisspeptin (Kiss) is crucial in regulating the hypothalamic-pituitary-gonadal axis. It is produced by two main groups of neurons in the hypothalamus: the rostral periventricular region around the third ventricle and the arcuate nucleus. Kiss is the peptide product of the KiSS-1 gene and serves as the endogenous agonist for the GPR54 receptor. The Kiss/GPR54 system functions as a critical regulator of the reproductive system. Thus, we examined the effect of intracerebroventricular administration of 3 µg of Kiss to the right lateral ventricle of ovariectomized rats primed with a dose of 5 µg subcutaneous (sc) of estradiol benzoate (EB). Kiss treatment increased the lordosis quotient at all times tested. However, the lordosis reflex score was comparatively lower yet still significant compared to the control group. To investigate receptor specificity and downstream mechanisms on lordosis, we infused 10 µg of GPR54 receptor antagonist, Kiss-234, 5 µg of the progestin receptor antagonist, RU486, or 3 µg of antide, a gonadotropin-releasing hormone-1 (GnRH-1) receptor antagonist, to the right lateral ventricle 30 min before an infusion of 3 µg of Kiss. Results demonstrated a significant reduction in the facilitation of lordosis behavior by Kiss at 60 and 120 min when Kiss-234, RU486, or antide were administered. These findings suggest that Kiss stimulates lordosis expression by activating GPR54 receptors on GnRH neurons and that Kiss/GPR54 system is an essential intermediary by which progesterone activates GnRH.

Kisspeptin signalling and its correlation with placental ultrastructure and clinical outcomes in pregnant South African women with obesity and gestational diabetes.

INTRODUCTION: Gestational diabetes mellitus (GDM) is a major pregnancy metabolic disorder and is strongly linked with obesity. Kisspeptin is a hormone that increases several thousand-fold in the maternal circulation during human pregnancy, with placenta as its main source. Studies have suggested that kisspeptin regulates trophoblast invasion and promotes pancreatic insulin secretion and peripheral insulin sensitivity. METHODS: In a well-characterized cohort of pregnant South African women and molecular and histological techniques, this study explored the impact and interaction of maternal obesity and GDM on kisspeptin (KISS1) signalling in relation to placental morphology and maternal and neonatal parameters. RESULTS: We found that GDM had no effect on placental KISS1 and KISS1R (KISS1 receptor) mRNA and/or protein expression. However, obesity reduced placental KISS1R mRNA expression even though overall KISS1 protein abundance or localization was not different from the non-obese group. Maternal and cord circulating KISS1 concentrations did not vary with obesity or GDM, but maternal circulating KISS1 was positively correlated with placenta weight in non-GDM obese women, and negatively correlated with placental intervillous space volume in non-GDM non-obese women. Cord serum KISS1 was positively correlated with infant weight in GDM obese women, but negatively correlated with maternal BMI in the non-obese GDM group. Placental syncytiotrophoblast extracellular vesicles exhibited detectable KISS1 and its abundance was ∼50 % lower in those from obese GDM compared to non-GDM women. DISCUSSION: This study shows maternal obesity and GDM can modulate placental kisspeptin signalling and placental morphological development with potential pathophysiological implications for clinically-relevant pregnancy and perinatal outcomes.

Structural basis for hormone recognition and distinctive Gq protein coupling by the kisspeptin receptor.

Kisspeptin signaling through its G protein-coupled receptor, KISS1R, plays an indispensable role in regulating reproduction via the hypothalamic-pituitary-gonadal axis. Dysregulation of this pathway underlies severe disorders like infertility and precocious puberty. Here, we present cryo-EM structures of KISS1R bound to the endogenous agonist kisspeptin-10 and a synthetic analog TAK-448. These structures reveal pivotal interactions between peptide ligands and KISS1R extracellular loops for receptor activation. Both peptides exhibit a conserved binding mode, unveiling their common activation mechanism. Intriguingly, KISS1R displays a distinct 40° angular deviation in its intracellular TM6 region compared to other Gq-coupled receptors, enabling distinct interactions with Gq. This study reveals the molecular intricacies governing ligand binding and activation of KISS1R, while highlighting its exceptional ability to couple with Gq. Our findings pave the way for structure-guided design of therapeutics targeting this physiologically indispensable receptor.

The role of KNDy neurons in human reproductive health.

In the early 2000s, metastin, an endogenous ligand for G protein-coupled receptor 54 (GPR54), was discovered in human placental extracts. In 2003, GPR54 receptor mutations were found in a family with congenital hypogonadotropic hypogonadism. Metastin was subsequently renamed kisspeptin after its coding gene, Kiss1. Since then, studies in mice and other animals have revealed that kisspeptin is located at the apex of the hypothalamic-pituitary-gonadal axis and regulates reproductive functions by modulating gonadotropin-releasing hormone (GnRH). In rodents, kisspeptin (Kiss1) neurons localize to two regions, the hypothalamic arcuate nucleus (ARC) and the anteroventral periventricular nucleus (AVPV). ARC Kiss1 neurons co-express neurokinin B (NKB) and dynorphin and are thus termed KNDy neurons. Kiss1 neurons in humans are concentrated in the infundibular nucleus (equivalent to the ARC), with few Kiss1 neurons localized to the preoptic area (equivalent to the AVPV), and the mechanisms underlying GnRH surge secretion in humans are poorly understood. However, peripheral administration of kisspeptin to humans promotes gonadotropin secretion, and administration of kisspeptin to patients with hypothalamic amenorrhea or congenital hypogonadotropic hypogonadism restores the pulsatile secretion of GnRH/luteinizing hormone. Thus, kisspeptin undoubtedly plays an important role in reproductive function in humans. Studies are currently underway to develop kisspeptin receptor agonists or antagonists for clinical application. Modification of KNDy neurons by NKB agonists/antagonists is also being attempted to develop therapeutic agents for various menstrual abnormalities, including polycystic ovary syndrome and menopausal hot flashes. Here, we review the role of kisspeptin in humans and its clinical applications.

Corrigendum: Epigallocatechin gallate decreases plasma triglyceride, blood pressure, and serum kisspeptin in obese human subjects.

[This corrects the article DOI: 10.1177/1535370220962708.].

Revolutionizing Infertility Management through Novel Peptide-based Targets.

Around 48 million couples and 186 million people worldwide have infertility; of these, approximately 85% have an identifiable cause, the most common being ovulatory dysfunctions, male infertility, polycystic ovary syndrome, and tubule disease. The remaining 15% have infertility for unknown reasons, including lifestyle and environmental factors. The regulation of the hypothalamic- pituitary-adrenal axis (HPA) is crucial for the secretion of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH), which are essential for female reproductive functions. GnRH is the primary reproductive axis regulator. The pattern of GnRH, FSH, and LH release is determined by its pulsatile secretion, which in turn controls endocrine function and gamete maturation in the gonads. Peptides called Kisspeptin (KP), Neurokinin-B (NKB), and Orexin influence both positive and negative feedback modulation of GnRH, FSH, and LH secretion in reproduction. This review article mainly focuses on the historical perspective, isoform, and signaling pathways of KP, NKB, and Orexin novel peptide-based targets including clinical and preclinical studies and having a promising effect in the management of infertility.

Kisspeptin expression during menstruation in PCOS patients undergoing ovulation induction and the correlation with early pregnancy.

PURPOSE: To examine the pattern of kisspeptin expression throughout the menstrual cycle in polycystic ovary syndrome (PCOS) patients under the ovulation induction and identify any possible associations with early pregnancy. MATERIALS AND METHODS: A prospective cohort of 80 PCOS women who expressed the desire for fertility was enrolled in this study. All of them received the ovulation induction by using letrozole. Levels of kisspeptin, luteinizing hormone (LH), and estradiol (E2) were measured at three different time points during menstruation. The early pregnancy rate was recorded for the study participants after three ovulation cycles. RESULTS: Kisspeptin levels varied regularly during the menstrual cycle, reaching a peak on the day of hCG injection and decreasing after ovulation. There was no significant correlation between kisspeptin and LH levels. Basal kisspeptin levels decreased after letrozole treatment without a significant difference while LH and E2 levels decreased significantly. PCOS participants who became pregnant early had higher basal kisspeptin levels compared to non-pregnant PCOS patients, which had a significant difference (P = 0.006). And the average basal kisspeptin level in pregnant patients was 2293.0 ± 398.7 pg/ml, with a 95% confidence interval of 1511.5-3074.5 pg/ml. CONCLUSION: Kisspeptin levels in PCOS women undergoing ovulation induction showed a regular variation, which was similar with the healthy women reported in previous studies. The use of LE may result in PCOS endocrine improvement and fertility achievement. In a certain range, kisspeptin might be a potential predictor for early pregnancy in PCOS patients as people with slightly higher basal kisspeptin levels seemed more likely to be pregnant.

Nasal application of kisspeptin-54 mitigates motor deficits by reducing nigrostriatal dopamine loss in hemiparkinsonian rats.

Parkinson's Disease is a progressive neurodegenerative disorder characterized by motor symptoms resulting from the loss of nigrostriatal dopaminergic neurons. Kisspeptins (KPs) are a family of neuropeptides that are encoded by the Kiss-1 gene, which exert their physiological effects through interaction with the GPR54 receptor. In the current investigation, we investigated the prospective protective effects of central KP-54 treatments on nigrostriatal dopaminergic neurons and consequent motor performance correlates in 6-hydroxydopamine (6-OHDA)-lesioned rats. Male adult Sprague Dawley rats underwent stereotaxic injection of 6-OHDA into the right medial forebrain bundle to induce hemiparkinsonism. Following surgery, rats received chronic central treatments of nasal or intracerebroventricular KP-54 (logarithmically increasing doses) for seven consecutive days. Motor performance was evaluated seven days post-surgery utilizing the open field test and catalepsy test. The levels of dopamine in the striatum were determined with mass spectrometry. Immunohistochemical analysis was conducted to assess the immunoreactivities of tyrosine hydroxylase (TH) and the GPR54 in the substantia nigra. The dose-response curve revealed a median effective dose value of ≈3 nmol/kg for both central injections. Due to its non-invasive and effective nature, nasal administration was utilized in the second phase of our study. Chronic administration of KP-54 (3nmol/kg, nasally) significantly protected 6-OHDA-induced motor deficits. Nasal KP-54 attenuated the loss of nigrostriatal dopaminergic neurons induced by 6-OHDA. Additionally, significant correlations were observed between motor performance and nigrostriatal dopamine levels. Immunohistochemical analysis demonstrated the localization of the GPR54 within TH-positive nigral cells. These findings suggest the potential efficacy of central KP-54 on motor impairments in hemiparkinsonism.