Kisspeptin and body weight homeostasis in relation to phenotypic features of polycystic ovary syndrome; metabolic regulation of reproduction

Multiple effects of kisspeptin on neuroendocrine, reproduction, and metabolism in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a highly prevalent and heterogeneous disease characterized by a combination of reproductive and endocrine abnormalities, often associated with metabolic and mental health disorders. The etiology and pathogenesis of PCOS remain unclear, but recent research has increasingly focused on the upstream mechanisms underlying its development. Among these, kisspeptin (KISS) signaling has emerged as a pivotal component in the regulation of the hypothalamic-pituitary-gonadal axis, with significant roles in reproductive function, energy regulation, and metabolism. Women with PCOS commonly exhibit disruptions in gonadotropin secretion, including elevated luteinizing hormone (LH) levels, imbalanced LH/follicle-stimulating hormone (FSH) ratios, and increased androgen levels, all of which are usually parallel with abnormal KISS signaling. Furthermore, alterations in the KISS/KISS1R system within the central and circulatory systems, as well as peripheral tissues, have been implicated in the development of PCOS. These changes affect multiple pathophysiological domains, including reproductive function, energy regulation, metabolic homeostasis, inflammatory response, and emotional disorders, and are further influenced by lifestyle and environmental factors. This review aims to comprehensively summarize the existing experimental and clinical evidence supporting these roles of KISS in PCOS, with the goal of establishing a foundation for future research and potential clinical applications.

Metabolic characteristics of obese patients with polycystic ovarian syndrome: a meta-analysis

OBJECTIVE

Though recent studies have pointed out different manifestations between obese and nonobese patients with polycystic ovarian syndrome (PCOS), there is no clear evidence to confirm this viewpoint. Therefore, the metabolic characteristics of obese and nonobese patients with PCOS were systematically compared through meta-analysis in this study.

METHODS

Data were searched from PubMed, Web of Science, Embase, Cochrane Library, CNKI, and Wanfang databases. Articles on obese and nonobese patients with PCOS published from database inception to January 2022 were included. Meta-analysis was performed using Stata 16.0 statistical software.

RESULTS

A total of 739 articles were initially retrieved, and ultimately 14 studies were involved in the meta-analysis. Specifically, there were 801 patients in the observation group (obese patients with PCOS) and 925 patients in the control group (nonobese patients with PCOS). Compared with the control group, the observation group had significantly lower levels of sex hormone-binding globulin (SHBG), high-density lipoprotein (HDL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and higher levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL). Nevertheless, there were no significant differences between the two groups in systolic blood pressure (SBP), diastolic blood pressure (DBP), glucose, and testosterone.

CONCLUSION

Compared with nonobese patients with PCOS, obese patients with PCOS have worse blood lipid parameters and lower levels of LH and FSH. Also, there are significant differences in metabolic characteristics between the two groups of patients. Most importantly, our findings provide guidance for the clinical diagnosis and treatment of PCOS.

Decreased neurokinin B as a risk factor of functional hypothalamic amenorrhea

BACKGROUND

Neurokinin B (NKB) belongs to the tachykinin family of proteins who's regulation is essential for proper function of the reproductive system. It has been shown that patients with functional hypothalamic amenorrhea (FHA) exhibit decreased levels of serum kisspeptin. As kisspeptin secretion is regulated by NKB signaling, it is reasonable to suspect that patients with FHA will also have abnormal NKB secretion.

AIM

To assess NKB levels in patients with FHA and to determine whether NKB signaling is affected in these patients. We hypothesized that decreased NKB signaling is a factor contributing to the development of the FHA.

MATERIALS AND METHODS

A total of 147 patients with FHA and 88 healthy age-matched controls were enrolled. Baseline blood samples were drawn from both groups to measure serum concentrations of NKB, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), prolactin (PRL), thyroid-stimulating hormone (TSH), free thyroxine (fT4), cortisol, dehydroepiandrosterone sulfate (DHEA-S), testosterone (T), glucose, and insulin.

RESULTS

Mean serum NKB levels were found to be decreased significantly in the FHA group when compared with the control group (628.35 ± 324.92 vs. 721.41 ± 337.57 ng/L, respectively p = 0.002). No statistical difference was observed in NKB-1 levels within the FHA group when selecting for normal and decreased body mass index.

CONCLUSIONS

Patients with FHA were found to have decreased serum NKB concentrations when compared to healthy controls. Abnormal NKB secretion is likely a key factor contributing to development of FHA.

The role of kisspeptin in the pathogenesis of a polycystic ovary syndrome

Hypothalamic-pituitary gonadal (HPG) axis is responsible for the development and regulation of the female reproductive system. In polycystic ovary syndrome (PCOS), there is a disturbance in the HPG axis. Kisspeptin, a neuropeptide produced by the KISS1 gene, plays a vital role in the regulation of HPG axis by binding with its receptors KISS1R/GPR54, and stimulates gonadotropin secretion from the hypothalamus into pituitary to release luteinizing hormone (LH) and follicle stimulating hormone (FSH). Polymorphisms or mutations in the KISS1 gene can cause disturbance in the kisspeptin signaling pathway and is thought to disrupt HPG axis. Altered signaling of kisspeptin can cause abnormal secretion of GnRH pulse, which leads to increased LH/FSH ratio, thereby affecting androgen levels and ovulation. The increased levels of androgen worsen the symptoms of PCOS. In the present article, we review the molecular physiology and pathology of kisspeptin and how it is responsible for the development of PCOS. The goal of this review article is to provide an overview and metabolic profile of kisspeptin in PCOS patients and the expression of kisspeptin in PCOS animal models. In the present article, we also review the molecular physiology and pathology of kisspeptin and how it is responsible for the development of PCOS.

Associations of the KiSS-1 and GPR54 genetic polymorphism with polycystic ovary syndrome in Yunnan, China

BSCKGROUND

Polycystic ovary syndrome (PCOS) is a heterogeneous condition that increases the risk for serious health complications among women. Thus, in this study, we aimed to identify polymorphisms in the KiSS-1 and GPR54 genes and investigate the associations between KiSS-1, BMI, FSH, LH, and estradiol in Chinese women with PCOS.

METHODS

This study recruited women with PCOS (n = 60) and controls (n = 60). We collected blood samples and measured endocrine indicators (kisspeptin, FSH, LH-FSH ratio, estradiol, prolactin, and testosterone). PCR and Snapshots were performed to screen single nucleotide polymorphisms (SNPs) of the KiSS-1 and GPR54 genes.

RESULTS

Compared with the controls, endocrine and metabolic disturbances in women with PCOS were reflected in significantly higher levels of BMI, LH, LH-FSH ratio, prolactin, and testosterone. Serum kisspeptin levels were significantly higher and positively correlated with LH and T levels (p < 0.05). No identified SNPs of KiSS-1 and GPR54 showed significant differences in frequency between patients and controls. The mutant G allele was highly predisposed to polymorphism in the PCOS GPR54 gene r10407968. We observed a significant difference in estradiol (p = 0.023, p = 0.012) after comparing the values of LH, FSH, estradiol, progesterone, and testosterone among the three genotypes of rs4889 and rs5780218. The KiSS-1 rs4889 CC genotype and rs5780218 AA genotype showed significantly higher estradiol levels compared with the other two genotypes.

CONCLUSIONS

These results suggest that kisspeptin plays a potential role in the etiology of PCOS.

Neuroendocrine Determinants of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women and a major cause of anovulatory infertility. A diagnosis of PCOS is established based the presence of two out of three clinical symptoms, which are criteria accepted by the ESHRE/ASRM (European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine). Gonadotropin-releasing hormone (GnRH) is responsible for the release of luteinizing hormone, and follicle stimulating hormone from the pituitary and contributes a leading role in controlling reproductive function in humans. The goal of this review is to present the current knowledge on neuroendocrine determinations of PCOS. The role of such neurohormones as GnRH, and neuropeptides kisspeptin, neurokinin B, phoenixin-14, and galanin is discussed in this aspect. Additionally, different neurotransmitters (gamma-aminobutyric acid (GABA), glutamate, serotonin, dopamine, and acetylcholine) can also be involved in neuroendocrine etiopathogenesis of PCOS. Studies have shown a persistent rapid GnRH pulse frequency in women with PCOS present during the whole ovulatory cycle. Other studies have proved that patients with PCOS are characterized by higher serum kisspeptin levels. The observations of elevated serum kisspeptin levels in PCOS correspond with the hypothesis that overactivity in the kisspeptin system is responsible for hypothalamic-pituitary-gonadal axis overactivity. In turn, this causes menstrual disorders, hyperandrogenemia and hyperandrogenism. Moreover, abnormal regulation of Neurokinin B (NKB) is also suspected of contributing to PCOS development, while NKB antagonists are used in the treatment of PCOS leading to reduction in Luteinizing hormone (LH) concentration and total testosterone concentration. GnRH secretion is regulated not only by kisspeptin and neurokinin B, but also by other neurohormones, such as phoenixin-14, galanin, and Glucagon-like peptide-1 (GLP-1), that have favorable effects in counteracting the progress of PCOS. A similar process is associated with the neurotransmitters such as GABA, glutamate, serotonin, dopamine, and acetylcholine, as well as the opioid system, which may interfere with secretion of GnRH, and therefore, influence the development and severity of symptoms in PCOS patients. Additional studies are required to explain entire, real mechanisms responsible for PCOS neuroendocrine background.

Emerging roles of kisspeptin/galanin in age-related metabolic disease

Age is a major risk factor for developing metabolic diseases such as obesity and diabetes. There is an unprecedented rise in obesity and type 2 diabetes in recent decades. A convincing majority of brain-gut peptides are associated with a higher risk to develop metabolic disorders, and may contribute to the pathophysiology of age-related metabolic diseases. Accumulating basic studies revealed an intriguing role of kisspeptin and galanin involved in the amelioration of insulin resistance in different ways. In patients suffered from obesity and diabetes a significant, sex-related changes in the plasma kisspeptin and galanin levels occurred. Kisspeptin is anorexigenic to prevent obesity, its level is negatively correlative with obesity and insulin resistance. While galanin is appetitive to stimulate food intake and body weight, its level is positively correlative with obesity, HOMA-IR and glucose/triglyceride concentration. In turn, kisspeptin and galanin also distinctly increase glucose uptake and utilization as well as energy expenditure. This article reviews recent evidence dealing with the role of kisspeptin and galanin in the pathophysiology of age-related metabolic diseases. It should be therefore taken into account that the targeted modulation of those peptidergic signaling may be potentially helpful in the future treatment of age-related metabolic diseases.

Circulating kisspeptin and anti-müllerian hormone levels, and insulin resistance in women with polycystic ovary syndrome: A systematic review, meta-analysis, and meta-regression

OBJECTIVE

This systematic review and meta-analysis aimed to summarize the available evidence regarding circulating kisspeptin and anti-müllerian hormone (AMH) and the homeostasis model assessment of insulin resistance (HOMA-IR) index in adolescents and women with and without polycystic ovary syndrome (PCOS).

METHOD

We performed a comprehensive literature search in Medline, Embase, Cochrane, Scopus, and Web of Science for studies evaluating circulating kisspeptin levels in women with and without PCOS published until September 24th, 2020. Co-primary outcomes were the HOMA-IR index and AMH. The quality of included studies was assessed using the Newcastle-Ottawa Scale. Random-effects models were used to estimate outcomes, and effects reported as mean difference (MD) or standardized MD (SMD) and their 95 % confidence interval (CI). The systematic review and meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO) as number CRD42020205030.

RESULTS

We evaluated 18 studies including, 1282 PCOS cases and 977 controls. Participants with PCOS were younger (MD = -2.38 years, 95 %CI -4.32 to -0.44), with higher BMI (MD = 1.16, 95 % CI 0.54-1.78), waist-to-hip ratio (MD = 0.04, 95 %CI 0.02 to 0.05), circulating kisspeptin (SMD = 1.15, 95 %CI 0.68-1.62), luteinizing hormone (SMD = 1.29, 95 %CI 0.76-1.83), AMH (SMD = 0.97, 95 %CI 0.60-1,34), total testosterone (SMD = 2.48, 95 %CI 1.73-3.23), free testosterone (SMD = 1.37, 95 %CI 0.56-2.17), and dehydroepiandrosterone sulphate (SMD = 0.72, 95 %CI 0.32-1.13) levels, and Ferriman-Gallwey score (SMD = 5.08, 95 %CI 2.76-7.39), and lower sex hormone-binding globulin level (SMD = -1.34, 95 %CI -2.15 to -0.52). Besides, participants with PCOS had higher HOMA-IR index (SMD = 0.76, 95 %CI 0.35-1.17), and circulating insulin (SMD = 0.75, 95 %CI 0.30-1.19), leptin (SMD = 2.82, 95 %CI 1.35-4.29), and triglycerides (SMD = 2.15, 95 %CI 1.08-3.23) levels than participants without the syndrome. The meta-regression did not identify significant factors influencing circulating kisspeptin.

CONCLUSION

Patients with PCOS showed higher kisspeptin, LH, insulin, AMH, and androgen levels and HOMA-IR index, and lower sex hormone-binding globulin levels than those without the syndrome.

Sample Preparation Methods for Lipidomics Approaches Used in Studies of Obesity

Obesity is associated with alterations in the composition and amounts of lipids. Lipids have over 1.7 million representatives. Most lipid groups differ in composition, properties and chemical structure. These small molecules control various metabolic pathways, determine the metabolism of other compounds and are substrates for the syntheses of different derivatives. Recently, lipidomics has become an important branch of medical/clinical sciences similar to proteomics and genomics. Due to the much higher lipid accumulation in obese patients and many alterations in the compositions of various groups of lipids, the methods used for sample preparations for lipidomic studies of samples from obese subjects sometimes have to be modified. Appropriate sample preparation methods allow for the identification of a wide range of analytes by advanced analytical methods, including mass spectrometry. This is especially the case in studies with obese subjects, as the amounts of some lipids are much higher, others are present in trace amounts, and obese subjects have some specific alterations of the lipid profile. As a result, it is best to use a method previously tested on samples from obese subjects. However, most of these methods can be also used in healthy, nonobese subjects or patients with other dyslipidemias. This review is an overview of sample preparation methods for analysis as one of the major critical steps in the overall analytical procedure.

Serum Kisspeptin and Its Relation to Metabolic Parameters and Glucose Metabolism in Prepubertal and Pubertal Obese Children

OBJECTIVE

Kisspeptin, a puberty control neuropeptide, has been discovered to have an additional role in metabolism and glucose homeostasis regulation. This study aimed to determine the association of serum kisspeptin with metabolic parameters and glucose metabolism in obese children. Design, Patients and Measurements. A cross-sectional study of 270 obese children was conducted. All children underwent an oral glucose tolerance test and had serum kisspeptin, glycated hemoglobin (HbA1c), and lipid profile measurements. Body fat mass was assessed by bioelectrical impedance analysis. Serum kisspeptin levels of both prepubertal and pubertal children with two HbA1c ranges, <5.7% (normal range) and 5.7-6.4% (prediabetes range), were analyzed and correlated with metabolic parameters and glucose metabolism status.

RESULTS

The median (IQR) serum kisspeptin level of only pubertal (not prepubertal) children with prediabetes HbA1c was higher than those with normal HbA1c (53.2 (33.9, 69.8) and 37.8 (29.6, 67.5) pg/mL; p = 0.015, respectively). There were no differences in serum kisspeptin levels among children with different glucose metabolism status. During pubertal progression, serum kisspeptin reached the highest level at Tanner stage II only in obese boys. Additionally, there was a positive correlation between serum kisspeptin and HbA1c after adjusting for puberty (β = 12.87; p = 0.001). No correlations between serum kisspeptin and insulin sensitivity indices, insulin secretion indices, lipid profile, blood glucose, as well as percentage of body fat were demonstrated.

CONCLUSIONS

Serum kisspeptin levels in pubertal obese children with prediabetes HbA1c were greater than those with normal HbA1c. Serum kisspeptin was positively associated with HbA1c, but not with glucose metabolism status.