Evaluation of kisspeptin levels in obese pregnancy as a biomarker for pre-eclampsia

Associations between maternal urinary kisspeptin in late pregnancy and decreased fetal growth: a pregnancy-birth cohort study

Background

Kisspeptin has been indicated to be a biomarker of fetal growth. Although some evidence suggested that maternal kisspeptin concentrations in early pregnancy were associated with increased fetal growth, studies are still limited and the effect of kisspeptin in late pregnancy remains unknown. This study aimed to investigate the associations between maternal kisspeptin in late pregnancy and fetal growth.

Methods

Based on the Shanghai-Minhang Birth Cohort study, 724 mother-neonate pairs were included in this study. We measured maternal kisspeptin concentrations in the urine samples collected in late pregnancy and neonatal anthropometric indices at birth. The associations between maternal kisspeptin and neonatal anthropometry were investigated using multiple linear regression models.

Results

Higher maternal urinary kisspeptin concentrations were associated with lower neonatal birth weight, head circumference, upper arm circumference, abdominal skinfold thickness, triceps skinfold thickness, and back skinfold thickness. The inverse associations were more pronounced for the highest kisspeptin levels versus the lowest. These patterns were consistent in analyses stratified by neonatal sex, with notably stable associations between maternal kisspeptin concentrations and skinfold thickness.

Conclusion

The present study suggested that maternal kisspeptin concentrations in late pregnancy might be inversely associated with fetal growth. The physiological mechanisms of maternal kisspeptin might differ from those in early pregnancy. Further studies are required to assess associations between maternal kisspeptin and energy homeostasis and explore the physiological roles of kisspeptin in late pregnancy.

The Emerging Therapeutic Potential of Kisspeptin and Neurokinin B

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

KISS1 Gene Variations and Susceptibility to Idiopathic Recurrent Pregnancy Loss

It is widely accepted that kisspeptin plays an integral role in the regulation of reproduction. Genetic variations in the KISS1 gene have been frequently reported to be linked to reproductive diseases, but there is still a lack of data on the association between KISS1 variations and female reproductive disorders. The present study aimed to examine the association of three missense SNPs in the KISS1 gene including rs12998, rs35431622, and rs4889 in association with idiopathic recurrent pregnancy loss (iRPL). A total of 720 individuals were recruited in this study. The DNA from the blood sample was extracted and genotyped using the PCR method. Haplotype and linkage disequilibrium (LD) have also been analyzed. The results of this study suggested that rs12998 G > A and rs4889 C > G had a significant association with iRPL (p < 0.05); while rs35431622 A > G didn't indicate any association with iRPL. A significant association was also found for three haplotypes including C-A-A, G-G-G, and G-G-A in this population. The analysis also showed a significant LD between rs12998 and rs35431622 (P < 0.0005). The rs12998 G > A and rs4889 C > G variants of KISS1 are linked to unexplained recurrent pregnancy loss and may be risk factors for this disease.

Kisspeptin and GPR54 Receptor Expression in Endometrial Cancer Tissue

Kisspeptin (KISS) is a natural peptide-discovered in 1996 as a factor inhibiting the ability to metastasize in malignant melanoma. This protein plays also a regulatory role in the process of puberty, the menstrual cycle, spermatogenesis, implantation and development of the human placenta. The present study aimed to evaluate the expression of KISS and its receptor GPR54 in endometrial cancer (EC) tissue, depending on the histological type of cancer, its stage, various demographic characteristics, and clinical conditions in 214 hysterectomy patients. Expression of KISS and GPR54 was confirmed in 99.5% and 100% of the cases, respectively. Hormone replacement therapy and the coexistence of the anti-Müllerian type 2 receptor in cancer tissue enhanced KISS expression. Smoking, on the other hand, decreased KISS expression. GPR54 expression increased with the advancement of the disease (according to FIGO classification). Also, the presence of the anti-Müllerian type 2 receptor in EC increased the level of GPR54. Hypertension, age and miscarriage harmed the presence of GPR54. The histological type of cancer, diabetes type 2, body mass index, hormonal contraception, number of deliveries, birth weight of newborns, breastfeeding time, and the presence of AMH in EC tissue were not associated with the expression of either KISS nor GPR54. The KISS level was also significantly related to the GPR54 level. Considering that KISS is a non-toxic peptide with antimetastatic properties, further investigation is essential to determine the clinical significance of this peptide.

Effect of triclosan exposure on ovarian hormones, trace elements and growth in female rats

Triclosan (TCS) is an antibacterial compound used mainly in personal care products. Its widespread use for decades has made it one of the most widely detected compounds in environmental matrices and in biological fluids. Although it has been shown to be an endocrine disruptor in rats and aquatic species, its safe use by humans is unclear. The aim of the present study was to evaluate the effects of exposure to TCS in female rats. To this end, 14 rats were divided into two groups and fed daily as follows: the control group with sesame oil and the TCS group at a dose of 50 mg/kg/day for 28 days. Any signs of toxicity in the rats were observed daily, and the weight and phase of the estrous cycle were recorded. At the end, the rats were decapitated, the serum and ovaries were collected. The levels of testosterone and progesterone in serum were determined by immunoassay and mass spectrometry. Estradiol (in serum) and kisspeptin-10 (in serum and ovary) were measured only by immunoassays. Trace elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The weight gain study of the rats showed a significant decrease by exposure to TCS, while the estrous cycle was not significantly affected compared to the control. The optimized methods based on mass spectrometry showed a significant decrease in the levels of progesterone and testosterone due to exposure to TCS. In addition, elements determined by ICP-MS in rat serum showed significant changes in calcium, lithium and aluminum due to TCS treatment. Finally, the kisspeptin-10 levels did not show a negative effect due to the treatment by TCS. The results suggest that medium-term exposure to TCS did not significantly alter estrous cyclicity but caused alterations in growth, sex hormone levels and some elements in the rat serum.

Kisspeptin in the Prediction of Pregnancy Complications

Kisspeptin and its receptor are central to reproductive health acting as key regulators of the reproductive endocrine axis in humans. Kisspeptin is most widely recognised as a regulator of gonadotrophin releasing hormone (GnRH) neuronal function. However, recent evidence has demonstrated that kisspeptin and its receptor also play a fundamental role during pregnancy in the regulation of placentation. Kisspeptin is abundantly expressed in syncytiotrophoblasts, and its receptor in both cyto- and syncytio-trophoblasts. Circulating levels of kisspeptin rise dramatically during healthy pregnancy, which have been proposed as having potential as a biomarker of placental function. Indeed, alterations in kisspeptin levels are associated with an increased risk of adverse maternal and foetal complications. This review summarises data evaluating kisspeptin's role as a putative biomarker of pregnancy complications including miscarriage, ectopic pregnancy (EP), preterm birth (PTB), foetal growth restriction (FGR), hypertensive disorders of pregnancy (HDP), pre-eclampsia (PE), gestational diabetes mellitus (GDM), and gestational trophoblastic disease (GTD).

The Role of Kisspeptin in the Pathogenesis of Pregnancy Complications: A Narrative Review

Kisspeptins are the family of neuropeptide products of the KISS-1 gene that exert the biological action by binding with the G-protein coupled receptor 54 (GPR54), also known as the KISS-1 receptor. The kisspeptin level dramatically increases during pregnancy, and the placenta is supposed to be its primary source. The role of kisspeptin has already been widely studied in hypogonadotropic hypogonadism, fertility, puberty disorders, and insulin resistance-related conditions, including type 2 diabetes mellitus, polycystic ovary syndrome, and obesity. Gestational diabetes mellitus (GDM), preeclampsia (PE), preterm birth, fetal growth restriction (FGR), or spontaneous abortion affected 2 to 20% of pregnancies worldwide. Their occurrence is associated with numerous short and long-term consequences for mothers and newborns; hence, novel, non-invasive predictors of their development are intensively investigated. The study aims to present a comprehensive review emphasizing the role of kisspeptin in the most common pregnancy-related disorders and neonatal outcomes. The decreased level of kisspeptin is observed in women with GDM, FGR, and a high risk of spontaneous abortion. Nevertheless, there are still many inconsistencies in kisspeptin concentration in pregnancies with preterm birth or PE. Further research is needed to determine the usefulness of kisspeptin as an early marker of gestational and neonatal complications.

Maternal hypothyroidism reduces the expression of the kisspeptin/Kiss1r system in the maternal-fetal interface of rats

Alterations of circulating and placental levels of kisspeptin have been associated with gestational diseases. However, there are still no studies on the placental and decidual expression of Kiss1 and its receptor Kiss1r in maternal hypothyroidism, which is the aim of this work. We demonstrate that the fetoplacental restriction caused by hypothyroidism in rats is associated with a reduction in the Kiss1r expression and reduced Kiss1 and Kiss1r mRNA levels in the decidua and/or placenta. This demonstrate that fetoplacental restriction in hypothyroid rats is linked with a suppression of the kisspeptin/Kiss1r system at the maternal-fetal interface.

Kisspeptin treatment improves fetal-placental development and blocks placental oxidative damage caused by maternal hypothyroidism in an experimental rat model

Maternal hypothyroidism is associated with fetal growth restriction, placental dysfunction, and reduced kisspeptin/Kiss1R at the maternal-fetal interface. Kisspeptin affects trophoblastic migration and has antioxidant and immunomodulatory activities. This study aimed to evaluate the therapeutic potential of kisspeptin in the fetal-placental dysfunction of hypothyroid Wistar rats. Hypothyroidism was induced by daily administration of propylthiouracil. Kisspeptin-10 (Kp-10) treatment was performed every other day or daily beginning on day 8 of gestation. Feto-placental development, placental histomorphometry, and expression levels of growth factors (VEGF, PLGF, IGF1, IGF2, and GLUT1), hormonal (Dio2) and inflammatory mediators (TNFα, IL10, and IL6), markers of hypoxia (HIF1α) and oxidative damage (8-OHdG), antioxidant enzymes (SOD1, Cat, and GPx1), and endoplasmic reticulum stress mediators (ATF4, GRP78, and CHOP) were evaluated on day 18 of gestation. Daily treatment with Kp-10 increased free T3 and T4 levels and improved fetal weight. Both treatments reestablished the glycogen cell population in the junctional zone. Daily treatment with Kp-10 increased the gene expression levels of Plgf, Igf1, and Glut1 in the placenta of hypothyroid animals, in addition to blocking the increase in 8-OHdG and increasing protein and/or mRNA expression levels of SOD1, Cat, and GPx1. Daily treatment with Kp-10 did not alter the higher protein expression levels of VEGF, HIF1α, IL10, GRP78, and CHOP caused by hypothyroidism in the junctional zone compared to control, nor the lower expression of Dio2 caused by hypothyroidism. However, in the labyrinth zone, this treatment restored the expression of VEGF and IL10 and reduced the GRP78 and CHOP immunostaining. These findings demonstrate that daily treatment with Kp-10 improves fetal development and placental morphology in hypothyroid rats, blocks placental oxidative damage, and increases the expression of growth factors and antioxidant enzymes in the placenta.

Changes in Circulating Kisspeptin Levels During Each Trimester in Women With Antenatal Complications

CONTEXT

Antenatal complications such as hypertensive disorders of pregnancy (HDP), fetal growth restriction (FGR), gestational diabetes (GDM), and preterm birth (PTB) are associated with placental dysfunction. Kisspeptin has emerged as a putative marker of placental function, but limited data exist describing circulating kisspeptin levels across all 3 trimesters in women with antenatal complications.

OBJECTIVE

We aimed to assess whether kisspeptin levels are altered in women with antenatal complications.

METHODS

Women with antenatal complications (n = 105) and those with uncomplicated pregnancies (n = 265) underwent serial ultrasound scans and blood sampling at the Early Pregnancy Assessment Unit at Hammersmith Hospital, UK, at least once during each trimester (March 2014 to March 2017). The women with antenatal complications (HDP [n = 32], FGR [n = 17], GDM [n = 35], PTB [n = 11], and multiple complications [n=10]) provided 373 blood samples and the controls provided 930 samples. Differences in circulating kisspeptin levels were assessed.

RESULTS

Third-trimester kisspeptin levels were higher than controls in HDP but lower in FGR. The odds of HDP adjusted for gestational age, maternal age, ethnicity, BMI, smoking, and parity were increased by 30% (95% CI, 16%-47%; P < 0.0001), and of FGR were reduced by 28% (95% CI, 4-46%; P = 0.025), for every 1 nmol/L increase in plasma kisspeptin. Multiple of gestation-specific median values of kisspeptin were higher in pregnancies affected by PTB (P = 0.014) and lower in those with GDM (P = 0.020), but not significantly on multivariable analysis.

CONCLUSION

We delineate changes in circulating kisspeptin levels at different trimesters and evaluate the potential of kisspeptin as a biomarker for antenatal complications.

The relation between obesity, kisspeptin, leptin, and male fertility

Over the past decades, obesity and infertility in men increased in parallel, and the association between both phenomena have been examined by several researchers. despite the fact that there is no agreement, obesity appears to affect the reproductive potential of men through various mechanisms, such as changes in the hypothalamic-pituitary-testicular (HPT) axis, spermatogenesis, sperm quality and/or alteration of sexual health. Leptin is a hormone produced by the adipose tissue, and its production elevates with increasing body fat. Many studies have supported the relationship between raised leptin production and reproductive function regulation. In fact, Leptin acts on the HPT axis in men at all levels. However, most obese men are insensitive to increased production of endogenous leptin and functional leptin resistance development. Recently, it has been recommended that Kisspeptin neurons mediate the leptin's effects on the reproductive system. Kisspeptin binding to its receptor on gonadotropin-releasing hormone (GnRH) neurons, activates the mammal's reproductive axis and stimulates GnRH release. Increasing infertility associated with obesity is probably mediated by the Kisspeptin-GnRH pathway. In this review, the link between obesity, kisspeptin, leptin, and male fertility will be discussed.

Investigation of the usability of kisspeptin and oxidative stress parameters in the early diagnosis of asymptomatic cystic endometrial hyperplasia in dogs

This study aimed to investigate the differences in oxidative stress index (OSI) and kisspeptin levels in clinically asymptomatic dogs with cystic endometrial hyperplasia (CEH) compared to healthy and pregnant dogs, and to determine the usability of the obtained results in the diagnosis of asymptomatic CEH. The study comprised three groups; a healthy (n = 8), a pregnant (n = 10) and a CEH (n = 10). All dogs in the three groups were included in the study at the 30 ± 3th day after estrus, and blood samples were collected for analysis of kisspeptin, total antioxidant status (TAS), total oxidant status (TOS), progesterone (P4), estradiol (E2) and some biochemical parameters (TSH; thyroid stimulating hormone, ALT; alanine aminotransferase, AST; aspartate aminotransferase, ALP; alkaline phosphatase, LDH; lactate dehydrogenase, CRE; creatine and BUN; blood urea nitrogen). In addition, OSI value was calculated. P4 and ALT and BUN levels were significantly lower and higher in CEH group than the pregnant group, respectively (p < .05). While kisspeptin and TAS levels were significantly lower in CEH group compared to the healthy and pregnant groups (p < .01), OSI level increased dramatically. In conclusion, it was confirmed that CEH clearly affected kisspeptin and OSI levels, and it is thought that these parameters may be an alternative diagnostic tool for the detection of CEH after further studies.

From inhibition of trophoblast cell invasion to proapoptosis: what are the potential roles of kisspeptins in preeclampsia?

Preeclampsia (PE) is a life-threatening human gestational syndrome with incompletely understood etiopathogenesis. The disorder has a spectrum of clinical features, likely due to a complex interaction between maternal predisposing factors and abnormalities at the maternal-fetal interface. Poor trophoblast cell invasion, inadequate uterine vascular remodeling, and placental hypoperfusion are considered as key placental events leading to PE. Kisspeptins, a family of small peptides derived from the KISS1 gene, have been implicated in the development of this syndrome. Most studies of kisspeptin expression in PE have reported an upregulation of kisspeptins and/or their cognate receptor in preeclamptic placentas. Conversely, maternal peripheral blood concentration of kisspeptins is reportedly lower in PE than in uncomplicated pregnancies. This apparent paradox remains to be further elucidated. Although kisspeptins were initially known for inhibiting cellular migration and invasion, other biological activities attributed to these peptides include neuroendocrine regulation of reproduction, metabolism regulation, inhibition of angiogenesis, and induction of apoptosis. This review summarizes the current knowledge on expression and biological activity of kisspeptins at the maternal-fetal interface in the context of PE.

Role of kisspeptins in the control of the hypothalamic-pituitary-ovarian axis: old dogmas and new challenges

In humans and other mammals, a hallmark of female reproductive function is the capacity to episodically release fertilizable oocytes under the precise control of a cascade of hormonal regulators that interplay in a cyclic manner within the hypothalamic-pituitary-ovarian (HPO) axis. Although the basic elements of this neurohormonal system were disclosed several decades before, a major breakthrough in our understanding of how the HPO axis is controlled during the lifespan came in the first decade of the 21st century, when the reproductive dimension of kisspeptins was disclosed by seminal studies documenting that genetic inactivation of the kisspeptin pathway is linked to central hypogonadism and infertility. Kisspeptins are a family of peptides, encoded by the Kiss1 gene, that operate via the surface receptor, Gpr54 (also called Kiss1r), to regulate virtually all aspects of reproduction in both sexes. The primary site of action of kisspeptins is the hypothalamus, where Kiss1 neurons engage in the precise control of the pulsatile release of GnRH to modulate gonadotropin secretion and, thereby, ovarian function. Nonetheless, additional sites of action of kisspeptins within the HPO axis, including the pituitary and the ovary, have been proposed; yet, the physiologic relevance of such extrahypothalamic actions of kisspeptins is still a matter of debate. In this review, we summarize the current consensus knowledge and open questions on the sites of action, physiologic roles, and eventual therapeutic implications of kisspeptins in the control of the female reproductive axis.

Roles of the kisspeptin/GPR54 system in pathomechanisms of atherosclerosis

AIMS

Kisspeptin-10 (KP-10), a potent vasoconstrictor and inhibitor of angiogenesis, and its receptor, GPR54, have currently received much attention with respect to atherosclerosis, since both KP-10 and GPR54 are expressed at high levels in atheromatous plaques and restenotic lesions after wire-injury. The present review introduces the emerging roles of the KP-10/GPR54 system in atherosclerosis.

DATA SYNTHESIS

KP-10 suppresses migration and proliferation of human umbilical vein endothelial cells (HUVECs), and induces senescence in HUVECs. KP-10 increases adhesion of human monocytes to HUVECs. KP-10 also stimulates expression of interleukin-6, tumor necrosis factor-α, monocyte chemotactic protein-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin genes in HUVECs. KP-10 enhances oxidized low-density lipoprotein-induced foam cell formation associated with upregulation of CD36 and acyl-coenzyme A: cholesterol acyltransferase-1 in human monocyte-derived macrophages. In human aortic smooth muscle cells, KP-10 suppresses angiotensin II-induced migration and proliferation, however, it enhances apoptosis and activities of matrix metalloproteinase (MMP)-2 and MMP-9 by upregulation of extracellular signal-regulated kinase 1/2, p38, Bax, and caspase-3. Four-week-infusion of KP-10 into Apoe^-/- mice accelerates development of aortic atherosclerotic lesions with increased monocyte/macrophage infiltration and vascular inflammation, also, it decreases intraplaque vascular smooth muscle cell content. Proatherosclerotic effects of endogenous and exogenous KP-10 were completely attenuated upon infusion of P234, a GPR54 antagonist, in Apoe^-/- mice.

CONCLUSION

These findings suggest that KP-10 may contribute to acceleration of progression and to the instability of atheromatous plaques, leading to rupture of plaques. This GPR54 antagonist may be useful for the prevention and treatment of atherosclerosis. Thus, the KP-10/GPR54 system may serve as a novel therapeutic target for atherosclerotic diseases.

Potential roles for the kisspeptin/kisspeptin receptor system in implantation and placentation

BACKGROUND

Initially identified as suppressors of metastasis in various types of cancer, kisspeptins are a family of neuropeptides that are key regulators of the mammalian reproductive axis. Accumulating evidence has shown that kisspeptin is able to control both the pulsatile and surge GnRH release, playing fundamental roles in female reproduction, which include the secretion of gonadotropins, puberty onset, brain sex differentiation, ovulation and the metabolic regulation of fertility. Furthermore, recent studies have demonstrated the involvement of the kisspeptin system in the processes of implantation and placentation. This review summarizes the current knowledge of the pathophysiological role and utility of these local placental regulatory factors as potential biomarkers during the early human gestation.

OBJECTIVE AND RATIONALE

A successful pregnancy, from the initiation of embryo implantation to parturition, is a complex process that requires the orchestration of a series of events. This review aims to concisely summarize what is known about the role of the kisspeptin system in implantation, placentation, early human pregnancy and pregnancy-related disorders, and to develop strategies for predicting, diagnosing and treating these abnormalities.

SEARCH METHODS

Using the PubMed and Google Scholar databases, we performed comprehensive literature searches in the English language describing the advancement of kisspeptins and the kisspeptin receptor (KISS1R) in implantation, placentation and early pregnancy in humans, since its initial identification in 1996 and ending in July 2018.

OUTCOMES

Recent studies have shown the coordinated spatial and temporal expression patterns of kisspeptins and KISS1R during human pregnancy. The experimental data gathered recently suggest putative roles of kisspeptin signaling in the regulation of trophoblast invasion, embryo implantation, placentation and early pregnancy. Dysregulation of the kisspeptin system may negatively affect the processes of implantation as well as placentation. Clinical studies indicate that the circulating levels of kisspeptins or the expression levels of kisspeptin/KISS1R in the placental tissues may be used as potential diagnostic markers for women with miscarriage and gestational trophoblastic neoplasia.

WIDER IMPLICATIONS

Comprehensive research on the pathophysiological role of the kisspeptin/KISS1R system in implantation and placentation will provide a dynamic and powerful approach to understanding the processes of early pregnancy, with potential applications in observational and analytic screening as well as the diagnosis, prognosis and treatment of implantation failure and early pregnancy-related disorders.

Immunoreactivity of Kisspeptin and Kisspeptin Receptor in Eutopic and Ectopic Endometrial Tissue of Women With and Without Endometriosis

Endometriosis is characterized by the presence of ectopic endometrial tissues. Mechanisms of tissue dissemination in endometriosis may be similar to those involved in tumor metastasis. We hypothesize that dysregulation of kisspeptin (KISS1), a metastasis suppressor in endometrial carcinoma, may contribute to the pathogenesis of endometriosis. In this study, we characterized the immunoreactivity of kisspeptin and its receptor, KISS1R, in eutopic and ectopic endometrial tissue of women with and without endometriosis, in proliferative and secretory menstrual cycle phases. Immunohistochemistry was performed using KISS1 and KISS1R antibodies on samples from women with (n = 35) and without (n = 14) endometriosis. Samples from women with endometriosis included eutopic endometrium (n = 20) samples, superficial endometriotic implants (SUP, n = 10) deep infiltrating endometriotic implants (DIE, n = 15), and ovarian endometriomas (OMA, n = 15). Immunoreactivity was quantified using histoscores. KISS1 and KISS1R immunoreactivity was significantly lower in eutopic endometrial stroma of women with versus without endometriosis, regardless of the menstrual cycle phase (P = 0.001 and P = 0.015 respectively). In endometriotic implants, KISS1 levels were significantly lower in both glandular and stromal components of DIE (P < 0.01) and OMA (P < 0.01) compared to SUP. KISS1R immunoreactivity was lower in the glandular component of OMA (P = 0.035) compared to SUP. KISS1 and KISS1R levels are lower in eutopic endometrial stroma from women with versus without endometriosis, consistent with a role for decreased KISS1 expression in the pathogenesis of endometriosis. As deeply invasive lesions showed lower KISS1 levels than superficial lesions, downregulation of KISS1 levels may contribute to implant invasiveness.

A role for placental kisspeptin in β cell adaptation to pregnancy

During pregnancy the maternal pancreatic islets of Langerhans undergo adaptive changes to compensate for gestational insulin resistance. Kisspeptin has been shown to stimulate insulin release, through its receptor, GPR54. The placenta releases high levels of kisspeptin into the maternal circulation, suggesting a role in modulating the islet adaptation to pregnancy. In the present study we show that pharmacological blockade of endogenous kisspeptin in pregnant mice resulted in impaired glucose homeostasis. This glucose intolerance was due to a reduced insulin response to glucose as opposed to any effect on insulin sensitivity. A β cell–specific GPR54-knockdown mouse line was found to exhibit glucose intolerance during pregnancy, with no phenotype observed outside of pregnancy. Furthermore, in pregnant women circulating kisspeptin levels significantly correlated with insulin responses to oral glucose challenge and were significantly lower in women with gestational diabetes (GDM) compared with those without GDM. Thus, kisspeptin represents a placental signal that plays a physiological role in the islet adaptation to pregnancy, maintaining maternal glucose homeostasis by acting through the β cell GPR54 receptor. Our data suggest reduced placental kisspeptin production, with consequent impaired kisspeptin-dependent β cell compensation, may be a factor in the development of GDM in humans.

Placental kisspeptin regulates islet adaptation to pregnancy that is necessary for preventing gestational diabetes in mice and humans.

Kisspeptin as a potential biomarker throughout pregnancy

Kisspeptins are a family of neuropeptides that are critical for the puberty initiation and female fertility. Plasma or serum kisspeptin is mainly derived from the placenta during pregnancy and plasma kisspeptin levels significantly increase across pregnancy. Plasma kisspeptin levels could be used as a potential biomarker for the detection of miscarriage, pre-eclampsia, gestational trophoblastic neoplasia (GTN), and fetal development. Kisspeptin may also be involved in the process of parturition by stimulating oxytocin secretion during term pregnancy. This review discussed the potential use of kisspeptin as a marker across pregnancy and highlighted the unresolved problems in this area. Tweetable abstract: Plasma kisspeptin levels could be used as a potential biomarker across pregnancy.

Deregulation of miR-324/KISS1/kisspeptin in early ectopic pregnancy: mechanistic findings with clinical and diagnostic implications

BACKGROUND

Ectopic pregnancy is a life-threatening condition for which novel screening tools that would enable early accurate diagnosis would improve clinical outcomes. Kisspeptins, encoded by KISS1, play an essential role in human reproduction, at least partially by regulating placental function and possibly embryo implantation. Kisspeptin levels are elevated massively in normal pregnancy and reportedly altered in various gestational pathologic diseases. Yet, the pathophysiologic role of KISS1/kisspeptin in ectopic pregnancy has not been investigated previously.

OBJECTIVE

The purpose of this study was to evaluate changes of KISS1/kisspeptin levels in ectopic pregnancy and their underlaying molecular mechanisms and to ascertain the diagnostic implications of these changes.

STUDY DESIGN

A total of 122 women with normal pregnancy who underwent voluntary termination of pregnancy and 84 patients who experienced tubal ectopic pregnancy were recruited. Measurements of plasma kisspeptins and KISS1 expression analyses in human embryonic/placental tissue were conducted in ectopic pregnancy and voluntary termination of pregnancy control subjects during the early gestational window (<12 weeks). Putative microRNA regulators of KISS1 were predicted in silico, followed by expression analyses of selected microRNAs and validation of repressive interactions in vitro. Circulating levels of these microRNAs were also assayed in ectopic pregnancy vs voluntary termination of pregnancy.

RESULTS

Circulating kisspeptins gradually increased during the first trimester of normal pregnancy but were reduced markedly in ectopic pregnancy. This profile correlated with the expression levels of KISS1 in human embryonic/placental tissue, which increased in voluntary termination of pregnancy but remained suppressed in ectopic pregnancy. Bioinformatic predictions and expression analyses identified miR-27b-3p and miR-324-3p as putative repressors of KISS1 in human embryonic/placental tissue at <12 weeks gestation, when expression of microRNAs was low in voluntary termination of pregnancy control subjects but significantly increased in ectopic pregnancy. Yet, a significant repressive interaction was documented only for miR-324-3p, occurring at the predicted 3'-UTR of KISS1. Interestingly, circulating levels of miR-324-3p, but not of miR-27b-3p, were suppressed distinctly in ectopic pregnancy, despite elevated tissue expression of the pre-microRNA. A decision-tree model that used kisspeptin and miR-324-3p levels was successful in discriminating ectopic pregnancy vs voluntary termination of pregnancy, with a receiver-operating characteristic area under the curve of 0.95±0.02 (95% confidence interval).

CONCLUSION

Our results document a significant down-regulation of KISS1/kisspeptins in early stages of ectopic pregnancy via, at least partially, a repressive interaction with miR-324-3p. Our data identify circulating kisspeptins and miR-324-3p as putative biomarkers for accurate screening of ectopic pregnancy at early gestational ages.

Prognostic value of repeated serum kisspeptin measurements in early first trimester pregnancy: a preliminary study

RESEARCH QUESTION

What is the diagnostic value of maternal kisspeptin in patients with asymptomatic first-trimester pregnancies, and what is the prognostic significance of kisspeptin versus beta-HCG in early pregnancies.

DESIGN

Case-control study in academic medical centres. Patients with no confounding co-morbidities who conceived by IVF and intracytoplasmic sperm injection were analysed. Maternal serum samples were assessed at the time of pregnancy testing. Women who achieved a positive pregnancy test were asked to take serum samples 4 days later. According to the follow-up results, patients who experienced biochemical pregnancy loss (n = 24) and early miscarriage (n = 21), and women who achieved a viable pregnancy (n = 28), were included in this study. Serum samples were collected to detect kisspeptin and beta-HCG, respectively.

RESULTS

Single serum determinations of kisspeptin and beta-HCG were correlated with the different pregnancy outcomes. Women who experienced biochemical pregnancy loss showed lower kisspeptin levels than those in groups B and C. No significant difference, however, was observed at the time of pregnancy testing in women who had experienced early miscarriage and those who had achieved viable pregnancy. Sequential measurements of serum kisspeptin are not as effective as beta-HCG in determining pregnancy outcome. Increased kisspeptin level was associated with reduced miscarriage risk.

CONCLUSION

Single serum measurement of kisspeptin is significantly altered in pregnant and non-pregnant women. However, it failed to discriminate between miscarriage and ongoing pregnancies in first-trimester pregnancy. Neither single nor sequential kisspeptin have higher diagnostic performance for miscarriage than beta-HCG in early stage.

Cross talk between serum Kisspeptin-Leptin during assisted reproduction techniques

Background & objective:

Leptin facilitates onset of puberty by impact on hypothalamic Kisspeptin, gonadotropin releasing hormone, follicle stimulating and luteinizing hormone. The link of peripheral Leptin-Kisspeptin in regulating the ovarian and endometrial tissue in relation to adiposity is unknown. Therefore, we wanted to identify Kisspeptin-Leptin association with body mass index (BMI) and success of assisted reproductive treatments (ART) in infertile females.

Methods:

A cross sectional study was carried from August 2014 till May 2016 after receiving ethical approval at Australian Concept Infertility Medical Centre, and Aga Khan University. The study group comprised of females with an age range of 25-37 year who had duration of unexplained infertility for more than two years. They were grouped as; underweight (<18 kg/m²), normal weight (18-22.9 kg/m²), overweight 23-24.99 kg/m² and obese (>25 kg/m²). Kisspeptin and Leptin levels were measured by enzyme linked immune sorbent assay before down regulation of ovaries and initiation of treatment protocol of ART. Failure of procedure was detected by beta human chorionic gonadotropin <25mIU/ml (non-pregnant) whereas females with levels >25mIU/ml and cardiac activity on trans-vaginal scan were declared pregnant.

Results:

Highest Kisspeptin and Leptin levels were seen in normal weight group (374.80 ± 185.08ng/L; 12.78 ± 6.8 pg/ml) respectively, yet the highest number of clinical pregnancy was observed in overweight group (42%).A strong correlation of Kisspeptin with Leptin (r=0.794, p=0.001) was observed in the overweight females.

Conclusion:

Leptin-Kisspeptin-fertility link is expressed by maximum number of clinical pregnancies in the female group that showed strongest relationship between serum Leptin and Kisspeptin levels, irrespective of their BMI.

Serum Levels of Spexin and Kisspeptin Negatively Correlate With Obesity and Insulin Resistance in Women

Spexin (SPX) and kisspeptin (KISS) are novel peptides relevant in the context of regulation of metabolism, food intake, puberty and reproduction. Here, we studied changes of serum SPX and KISS levels in female non-obese volunteers (BMI<25 kg/m2) and obese patients (BMI>35 kg/m2). Correlations between SPX or KISS with BMI, McAuley index, QUICKI, HOMA IR, serum levels of insulin, glucagon, leptin, adiponectin, orexin-A, obestatin, ghrelin and GLP-1 were assessed. Obese patients had lower SPX and KISS levels as compared to non-obese volunteers (SPX: 4.48±0.19 ng/ml vs. 6.63±0.29 ng/ml; p<0.001, KISS: 1.357±0.15 nmol/l vs. 2.165±0.174 nmol/l; p<0.01). SPX negatively correlated with BMI, HOMA-IR, insulin, glucagon, active ghrelin and leptin. Positive correlations were found between SPX and QUICKI index, McAuley index, serum levels of obestatin, GLP-1 and adiponectin and orexin-A Serum KISS negatively correlated with BMI, HOMA-IR, serum levels of insulin, glucagon, active ghrelin and leptin. KISS positively correlated with QUICKI index, McAuley index and adiponectin. In summary, SPX and KISS show negative correlations with obesity, insulin resistance indices, and hormones known to affect insulin sensitivity in females. Both, SPX and KISS could be therefore relevant in the pathophysiology of obesity and insulin resistance.

The correlation between birth weight and insulin-like growth factor-binding protein-1 (IGFBP-1), kisspeptin-1 (KISS-1), and three-dimensional fetal volume

PURPOSE

This study aimed to determine the relationship between birth weight, and maternal serum insulin-like growth factor-binding protein-1 (IGFBP-1) and kisspeptin-1 (KISS-1) levels, and first-trimester fetal volume (FV) based on three-dimensional ultrasonography.

MATERIALS AND METHODS

The study included 142 pregnant women at gestational week 11°-13⁶. All fetuses were imaged ultrasonographically by the same physician. Maternal blood samples were collected at the time of ultrasonographic evaluation and analyzed for IGFBP-1 and KISS-1 levels via enzyme-linked immunosorbent assay (ELISA). Maternal and neonatal weights were recorded at birth. Birth weight ≤10th and the >90th percentiles was defined as small and large for gestational age (SGA and LGA), respectively.

RESULTS

Median crown-rump length (CRL), FV, and maternal serum IGFBP-1 and KISS-1 levels were 58.2 mm (35.3-79.2 mm), 16.3 cm³ (3.8-34.4 cm³), 68.1 ng mL^-1 (3.8-377.9 mL^-1), and 99.7 ng L^-1 (42.1-965.3 ng L^-1), respectively. First-trimester IGFBP-1 levels were significantly lower in the mothers with LGA neonates (p < .05). There was a significant positive correlation between CRL and FV, and between the IGFBP-1 and KISS-1 levels. IGFBP-1 levels and maternal weight at delivery were negatively correlated with neonatal birth weight. There was no correlation between CRL or FV and maternal IGFBP-1 or KISS1 levels (p > .05). The maternal IGFBP-1 level during the first trimester was a significant independent factor for SGA and LGA neonates (Odds ratio (OR): 0.011, 95%CI: 1.005-1.018, p < .001; and OR: 1.297, 95%CI: 1.074-1.566, p = .007, respectively). There was no significant relationship between SGA or LGA, and CRL, FV, or the KISS-1 level.

CONCLUSIONS

As compared to the maternal KISS-1 level, the maternal IGFBP-1 level during the first trimester might be a better biomarker of fetal growth. Additional larger scale studies are needed to further delineate the utility of IGFBP-1 as a marker of abnormal birth weight.

Kisspeptin Is a Novel Regulator of Human Fetal Adrenocortical Development and Function: A Finding With Important Implications for the Human Fetoplacental Unit

CONTEXT

The human fetal adrenal (HFA) is an integral component of the fetoplacental unit and important for the maintenance of pregnancy. Low kisspeptin levels during pregnancy are associated with miscarriage, and kisspeptin and its receptor are expressed in the HFA. However, the role of kisspeptin in fetal adrenal function remains unknown.

OBJECTIVE

To determine the role of kisspeptin in the developing HFA.

DESIGN

Experiments using H295R and primary HFA cells as in vitro models of the fetal adrenal. Association of plasma kisspeptin levels with HFA size in a longitudinal clinical study.

SETTING

Academic research center and tertiary fetal medicine unit.

PARTICIPANTS

Thirty-three healthy pregnant women were recruited at their 12-week routine antenatal ultrasound scan.

MAIN OUTCOME MEASURES

The spatiotemporal expression of Kiss1R in the HFA. The production of dehydroepiandrosterone sulfate (DHEAS) from HFA cells after kisspeptin treatment, alone or in combination with adrenocorticotropic hormone or corticotropin-releasing hormone. Fetal adrenal volume (FAV) and kisspeptin levels at four antenatal visits (∼20, 28, 34, and 38 weeks' gestation).

RESULTS

Expression of Kiss1R was present in the HFA from 8 weeks after conception to term and was shown in the inner fetal zone. Kisspeptin significantly increased DHEAS production in H295R and second-trimester HFA cells. Serial measurements of kisspeptin confirmed a correlation with FAV growth in the second trimester, independent of sex or estimated fetal weight.

CONCLUSIONS

Kisspeptin plays a key role in the regulation of the HFA and thus the fetoplacental unit, particularly in the second trimester of pregnancy.

The role of kisspeptin and RFRP in the circadian control of female reproduction

In female mammals, reproduction shows ovarian and daily rhythms ensuring that the timing of the greatest fertility coincides with maximal activity and arousal. The ovarian cycle, which lasts from a few days to a few weeks, depends on the rhythm of follicle maturation and ovarian hormone production, whereas the daily cycle depends on a network of circadian clocks of which the main one is located in the suprachiasmatic nuclei (SCN). In the last ten years, major progress has been made in the understanding of the neuronal mechanisms governing mammalian reproduction with the finding that two hypothalamic Arg-Phe-amide peptides, kisspeptin (Kp) and RFRP, regulate GnRH neurons. In this review we discuss the pivotal role of Kp and RFRP neurons at the interface between the SCN clock signal and GnRH neurons to properly time gonadotropin-induced ovulation. We also report recent findings indicating that these neurons may be part of the multi-oscillatory circadian system that times female fertility. Finally, we will discuss recent investigations indicating a role, and putative therapeutic use, of these neuropeptides in human reproduction.

Inter-organ communication and regulation of beta cell function

The physiologically predominant signal for pancreatic beta cells to secrete insulin is glucose. While circulating glucose levels and beta cell glucose metabolism regulate the amount of released insulin, additional signals emanating from other tissues and from neighbouring islet endocrine cells modulate beta cell function. To this end, each individual beta cell can be viewed as a sensor of a multitude of stimuli that are integrated to determine the extent of glucose-dependent insulin release. This review discusses recent advances in our understanding of inter-organ communications that regulate beta cell insulin release in response to elevated glucose levels.

The endocrine function of human placenta: an overview

During pregnancy, several tightly coordinated and regulated processes take place to enable proper fetal development and gestational success. The formation and development of the placenta is one of these critical pregnancy events. This organ plays essential roles during gestation, including fetal nourishment, support and protection, gas exchange and production of several hormones and other mediators. Placental hormones are mainly secreted by the syncytiotrophoblast, in a highly and tightly regulated way. These hormones are important for pregnancy establishment and maintenance, exerting autocrine and paracrine effects that regulate decidualization, placental development, angiogenesis, endometrial receptivity, embryo implantation, immunotolerance and fetal development. In addition, because they are released into maternal circulation, the profile of their blood levels throughout pregnancy has been the target of intense research towards finding potential robust and reliable biomarkers to predict and diagnose pregnancy-associated complications. In fact, altered levels of these hormones have been associated with some pathologies, such as chromosomal anomalies or pre-eclampsia. This review proposes to revise and update the main pregnancy-related hormones, addressing their major characteristics, molecular targets, function throughout pregnancy, regulators of their expression and their potential clinical interest.

Comprehensive Review on Kisspeptin and Its Role in Reproductive Disorders

Kisspeptin has recently emerged as a key regulator of the mammalian reproductive axis. It is known that kisspeptin, acting centrally via the kisspeptin receptor, stimulates secretion of gonadotrophin releasing hormone (GnRH). Loss of kisspeptin signaling causes hypogonadotrophic hypogonadism in humans and other mammals. Kisspeptin interacts with other neuropeptides such as neurokinin B and dynorphin, to regulate GnRH pulse generation. In addition, a growing body of evidence suggests that kisspeptin signaling be regulated by nutritional status and stress. Kisspeptin may also represent a novel potential therapeutic target in the treatment of fertility disorders. Early human studies suggest that peripheral exogenous kisspeptin administration stimulates gonadotrophin release in healthy adults and in patients with certain forms of infertility. This review aims to concisely summarize what is known about kisspeptin as a regulator of reproductive function, and provide an update on recent advances within this field.

Serum kisspeptin levels in normal and overweight Saudi females and its relation with anthropometric indices

BACKGROUND AND OBJECTIVES

Animal studies suggest that undernutrition and low body weight are associated with low kisspeptin expression and vice versa. This led us to hypothesize that obese and overweight individuals might have significant differences in kisspeptin levels compared with normal-weight individuals.

DESIGN AND SETTINGS

A prospective cohort study of 1-year duration involving young Saudi female students in the University of Dammam.

SUBJECTS AND METHODS

Young Saudi females studying in a Saudi university were divided into 2 groups: normal weight with a body mass index (BMI)=18.5-24.99 and overweight/obese with a BMI >=25. Serum kisspeptin levels were measured by enzyme-linked immunosorbent assay in early follicular, pre-ovulatory, and luteal phases, and anthropometric parameters were recorded.

RESULTS

Mean serum kisspeptin levels in the overweight/obese group (follicular phase: 266.88 [45.53], pre.ovulatory phase: 477.12 [21.18], and luteal phase: 735.13 [52.59]) did not differ significantly compared with the normal-weight group (follicular phase: 259.82 [20.50], pre-ovulatory phase: 448.36 [24.58], and luteal phase 708.18 [49.47]) in any of the menstrual phase. In any of the menstrual phase, kisspeptin levels were not found to be correlated with any of the anthropometric variable in any group.

CONCLUSION

Serum kisspeptin levels in overweight and obese young females may not differ significantly compared with normal-weight females, and there may not be any correlation between serum kisspeptin and anthropometric indices.

The relationship between circulating kisspeptin and sexual hormones levels in healthy females

The kisspeptin (metastin) is an endogenous peptide, which regulates human reproduction by modulating gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin was detected in peripheral blood, although GnRH was not. Previously, we measured plasma kisspeptin levels in male healthy subjects and patients with hypogonadism using enzyme immunoassay (EIA) to elucidate a normal range in healthy males and clinical implications of kisspeptin in male hypogonadism. We suggested that the plasma kisspeptin levels were received feedback from testosterone. In this study, we focused female subjects and elucidated the relationship between menstrual cycle and plasma kisspeptin levels to understand kisspeptin-hypothalamic-pituitary-gonadal axis. We measured plasma kisspeptin levels in eight female volunteers. The plasma kisspeptin levels in female are significantly higher than those in male. There are no significant correlation between plasma kisspeptin levels and sexual hormones. We revealed that the kisspeptin might stimulate a start of menstruation as a trigger, and progress menstruation covered for weakened ovarian function. We suggest that kisspeptin may be closely related with menstrual cycle and that the measurement of plasma kisspeptin levels is useful for understanding of reproductive system.

Potential Clinical Use of Kisspeptin

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

Reduced levels of plasma kisspeptin during the antenatal booking visit are associated with increased risk of miscarriage

CONTEXT

Kisspeptin is a recently identified hormone encoded by the KISS1 gene, playing a critical role in human reproduction. Plasma kisspeptin levels rise dramatically during normal pregnancy due to placental synthesis, which implicates it as a potential tool for assessing risks of pregnancy complications. No previous prospective study has investigated the association between plasma kisspeptin and risk of miscarriage.

OBJECTIVE

The objective of the study was to determine whether a single plasma kisspeptin or serum human chorionic gonadotropin (hCG) measurement in asymptomatic women attending their booking antenatal visit is associated with miscarriage.

DESIGN

This was a prospective cohort study.

SETTING

The study was conducted at a tertiary obstetric center.

PARTICIPANTS

A total of 993 asymptomatic pregnant women with a gestation of 6 weeks or longer attending routine antenatal booking visit were recruited between January 2010 and December 2012.

MAIN OUTCOME MEASURES

Plasma kisspeptin and serum hCG were measured during the antenatal booking visit. Pregnancy outcome was recorded prospectively.

RESULTS

Plasma kisspeptin correlated with gestation (r(2) = 0.57; P < .0001). Gestational age-corrected (multiples of median) plasma kisspeptin was 60.4% lower (P < .001), and multiples of median-hCG was 36.1% lower (P < .001) in women later diagnosed with miscarriage compared with women without miscarriage. Increased plasma kisspeptin was associated with reduced miscarriage risk, even after adjusting for age, body mass index, gestational age, smoking, and blood pressure [odds ratio 0.13 (95% confidence interval 0.08-0.22), P = .0001]. Kisspeptin had a higher diagnostic performance for miscarriage than hCG (receiver-operator characteristic-area under the curve 0.899 ± 0.025 plasma kisspeptin; 0.775 ± 0.040, serum hCG, P < .01 vs plasma kisspeptin).

CONCLUSION

Our data suggest for the first time that a single plasma kisspeptin measurement taken during the antenatal booking visit provides a potential novel marker for identifying asymptomatic pregnant women at a gestation of 6 weeks or greater at increased risk of miscarriage.

Kiss1 mutant placentas show normal structure and function in the mouse

Introduction

Kisspeptins, encoded by the Kiss1 gene, are a set of related neuropeptides that are required for activation of the mammalian reproductive axis at puberty and to maintain fertility. In addition, kisspeptin signaling via the G-protein coupled receptor GPR54 (KISS1R) has been suggested to regulate human placental formation and correlations have been found between altered kisspeptin levels in the maternal blood and the development of pre-eclampsia.

Methods

We have used Kiss1 and Gpr54 mutant mice to investigate the role of kisspeptin signaling in the structure and function of the mouse placenta.

Results

Expression of Kiss1 and Gpr54 was confirmed in the mouse placenta but no differences in birth weight were found in mice that had been supported by a mutant placenta during fetal development. Stereological measurements found no differences between Kiss1 mutant and wild-type placentas. Measurement of amino-acid and glucose transport across the Kiss1 mutant placentas at E15.5 days did not reveal any functional defects.

Discussion

These data indicate that mouse placentas can develop a normal structure and function without kisspeptin signaling and can support normal fetal development and growth.

•

The structure and function of Kiss1 and Gpr54 mutant placentas was examined in transgenic mice.

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Kiss1 and Gpr54 mutant placentas are not associated with fetal loss during gestation or reduced pup weight at birth.

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Kiss1 mutant placentas show normal structural components.

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Kiss1 mutant placentas show normal transport of glucose and amino-acids.

Luteal phase dynamics of follicle-stimulating and luteinizing hormones in obese and normal weight women

OBJECTIVES

Female obesity is a state of relative hypogonadotrophic hypogonadism. The aim of this study is to examine gonadotrophin secretion and response to gonadotrophin-releasing hormone (GnRH) in the luteal phase of the menstrual cycle and to investigate the pharmacodynamics and pharmacokinetics of endogenous and exogenous luteinizing hormone (LH) in obese women.

DESIGN

Participants underwent a luteal phase frequent blood sampling study. Endogenous LH pulsatility was observed, gonadotrophin-releasing hormone (GnRH) was given in two weight-based doses, and GnRH antagonist was administered followed by recombinant LH.

PATIENTS

Regularly menstruating obese (n = 10) and normal weight (n = 10) women.

MEASUREMENTS

Endogenous hypothalamic-pituitary function (as measured by LH pulsatility), pituitary sensitivity (GnRH-induced LH secretion), pharmacodynamics of endogenous LH and pharmacokinetics of exogenous LH were compared between the obese and normal weight groups.

RESULTS

There were no statistically significant differences in endogenous LH pulsatility or pituitary responses to two weight-based doses of GnRH between the obese and normal weight women. There were no differences in the pharmacodynamics of endogenous LH or the pharmacokinetics of exogenous LH between the groups. FSH dynamics did not differ between the groups throughout the study.

CONCLUSIONS

The relative hypogonadotrophic hypogonadism of obesity cannot be explained by differences in LH and FSH luteal phase dynamics or differences in endogenous LH pharmacodynamics or exogenous LH pharmacokinetics.

Menstrual cyclic change of metastin/GPR54 in endometrium

Metastin/kisspeptin is encoded by KISS1 and functions as an endogenous ligand of GPR54. Interaction of metastin with GPR54 suppresses metastasis and also regulates release of gonadotropin-releasing hormone, which promotes secretion of estradiol (E2) and progesterone (P4). We have previously demonstrated epigenetic regulation of GPR54 in endometrial cancer and the potent role of metastin peptides in inhibiting metastasis in endometrial cancer. However, little is known about how the metastin-GPR54 axis is regulated in the endometrium, the precursor tissue of endometrial cancer. Endometrial stromal cells (ESCs) and endometrial glandular cells (EGCs) within the endometrium show morphological changes when exposed to E2 and P4. In this study, we show that metastin expression is induced in ESCs through decidualization, but is repressed in glandular components of atypical endometrial hyperplasia (AEH) and endometrial cancer relative to EGCs. The promoter of GPR54 is unmethylated in normal endometrium and in AEH. These results indicate metastin may function in decidualized endometrium to prepare for adequate placentation but this autocrine secretion of metastin is deregulated during oncogenesis to enable tumor cells to spread.

Glucagon regulates hepatic kisspeptin to impair insulin secretion

Early in the pathogenesis of type 2 diabetes mellitus (T2DM), dysregulated glucagon secretion from pancreatic α cells occurs prior to impaired glucose-stimulated insulin secretion (GSIS) from β cells. However, whether hyperglucagonemia is causally linked to β cell dysfunction remains unclear. Here we show that glucagon stimulates via cAMP-PKA-CREB signaling hepatic production of the neuropeptide kisspeptin1, which acts on β cells to suppress GSIS. Synthetic kisspeptin suppresses GSIS in vivo in mice and from isolated islets in a kisspeptin1 receptor-dependent manner. Kisspeptin1 is increased in livers and in serum from humans with T2DM and from mouse models of diabetes mellitus. Importantly, liver Kiss1 knockdown in hyperglucagonemic, glucose-intolerant, high-fat-diet fed, and Lepr(db/db) mice augments GSIS and improves glucose tolerance. These observations indicate a hormonal circuit between the liver and the endocrine pancreas in glycemia regulation and suggest in T2DM a sequential link between hyperglucagonemia via hepatic kisspeptin1 to impaired insulin secretion.

Kisspeptins and Reproduction: Physiological Roles and Regulatory Mechanisms

Procreation is essential for survival of species. Not surprisingly, complex neuronal networks have evolved to mediate the diverse internal and external environmental inputs that regulate reproduction in vertebrates. Ultimately, these regulatory factors impinge, directly or indirectly, on a final common pathway, the neurons producing the gonadotropin-releasing hormone (GnRH), which stimulates pituitary gonadotropin secretion and thereby gonadal function. Compelling evidence, accumulated in the last few years, has revealed that kisspeptins, a family of neuropeptides encoded by the Kiss1 gene and produced mainly by neuronal clusters at discrete hypothalamic nuclei, are pivotal upstream regulators of GnRH neurons. As such, kisspeptins have emerged as important gatekeepers of key aspects of reproductive maturation and function, from sexual differentiation of the brain and puberty onset to adult regulation of gonadotropin secretion and the metabolic control of fertility. This review aims to provide a comprehensive account of the state-of-the-art in the field of kisspeptin physiology by covering in-depth the consensus knowledge on the major molecular features, biological effects, and mechanisms of action of kisspeptins in mammals and, to a lesser extent, in nonmammalian vertebrates. This review will also address unsolved and contentious issues to set the scene for future research challenges in the area. By doing so, we aim to endow the reader with a critical and updated view of the physiological roles and potential translational relevance of kisspeptins in the integral control of reproductive function.

Altered placental expression of kisspeptin and its receptor in pre-eclampsia

Kisspeptin, originally identified as metastatin, important in preventing cancer metastasis, has more recently been shown to be important in pregnancy. Roles indicated for kisspeptin in pregnancy include regulating trophoblast invasion and migration during placentation. The pregnancy-specific disorder pre-eclampsia (PE) is now accepted to begin with inadequate trophoblast invasion and the current study therefore sets out to characterise placental expression of both kisspeptin (KISS1) and its receptor (KISS1R) throughout pregnancy and in PE. Placental tissue was obtained from women undergoing elective surgical termination of early pregnancy (n=10) and from women following Caesarean section at term in normal pregnancy (n=10) and with PE (n=10). Immunohistochemistry of paraffin embedded sections and western immunoblotting were performed to assess protein localisation and expression. Quantitative real-time PCR was carried out to evaluate mRNA expression of both KISS1 and KISS1R. Protein and mRNA expression was found to mirror each other with KISS1 expression found to be reduced in PE compared with that in normal term pregnancy. Interestingly, KISS1R expression at both the mRNA and protein levels was found to be increased in PE compared with that in normal term pregnancy. The current findings of increased KISS1R expression may represent a mechanism by which functional activity of KISS1 is higher in PE than in normal pregnancy. Higher levels of activity of KISS1R may be involved in inhibition of trophoblast invasion and angiogenesis, which are associated with PE.