Kisspeptin-10

Kisspeptin Research

What is the research background of Kisspeptin?  

In the late 20th century, with advances in research on tumor metastasis suppressor genes, scientists discovered the KiSS-1 gene in melanoma cells using modified subtractive hybridization in 1996. In 1999, the rat G protein-coupled receptor GPR54 was identified, and in 2001, studies confirmed that the product of the KiSS-1 gene is the endogenous ligand for GPR54, named Kisspeptin. Initially noted for its tumor metastasis-suppressive properties, this neuropeptide was later found to act as a key upstream regulatory element of the hypothalamic-pituitary-gonadal axis, playing a core role in the neuroendocrine regulation of vertebrate reproductive development. It also participates in multiple physiological processes such as reproductive behavior, mood regulation, growth metabolism, and feeding behavior. The discovery and functional research of Kisspeptin provide an important theoretical basis for exploring neuroendocrine regulatory mechanisms and treating related diseases.  

What is the mechanism of action of Kisspeptin?  

Reproductive Regulatory Mechanisms  

Regulation of the Hypothalamic-Pituitary-Gonadal (HPG) Axis: Kisspeptin plays a central role in reproductive regulation, primarily through modulation of the HPG axis. In mammals, Kisspeptin stimulates the secretion of gonadotropin-releasing hormone (GnRH). Specifically, Kisspeptin activates the pulsatile secretion of GnRH cells via G protein-coupled mechanisms through its receptor GPR54. For example, during puberty initiation, increased activity of hypothalamic Kisspeptin neurons promotes GnRH secretion, which in turn stimulates the pituitary gland to secrete gonadotropins (such as follicle-stimulating hormone FSH and luteinizing hormone LH). These hormones act on the gonads to promote gonadal development and sex hormone secretion, thereby initiating pubertal development^[1] .  

Direct Effects on Gonads: In addition to indirect regulation of reproduction through the HPG axis, Kisspeptin also has direct effects on gonads. Studies on oocytes from anestrous Tan sheep, for example, have shown that Kisspeptin significantly improves the in vitro maturation rate of Tan sheep oocytes and promotes oocyte maturation by upregulating gene expression. This suggests that Kisspeptin may directly participate in regulating follicular development in the gonads.  

What is Kisspeptin's mechanism of action? 

Interactions with Other Neuropeptides: In the hypothalamic arcuate nucleus, there is a class of Kisspeptin neurons that co-express glutamate, neurokinin B (NKB), and dynorphin (Dyn). These neurons exhibit intermittent synchronous activity to drive pulsatile hormone secretion^[2]. Studies in female mice have shown that spontaneous synchronization of ARN^{KISS} neurons highly depends on glutamate transmission via AMPA receptors and neurokinin B transmission, while inhibition of NMDA receptors and κ-opioid receptors has no effect on synchronization rate^[3]. In male mice, synchronization of ARN^{KISS} neurons arises from nearly random burst network activity within the population, critically dependent on local glutamate-AMPA signaling, with neurokinin B enhancing glutamate-induced synchronization, while dynorphin-κ-opioid tone within the network acts as a gating mechanism for synchronization initiation. This indicates complex interaction networks between Kisspeptin neurons and other neuropeptides in neuroendocrine regulation, collectively governing pulsatile hormone secretion ^[2].

Figure 1 Histograms showing the percentage of trials in which coincident calcium events occurred between ARN^{KISS} neurons in the brain slice under unstimulated conditions and following low frequency and high frequency stimulation of a single neuron in the absence and presence of CNQX or neurokinin receptor (NKR) antagonists.  

Source: PubMed^[3].

What is the progress of clinical research on Kisspeptin in the treatment of metabolic diseases? 

Kisspeptin and Type 2 Diabetes Mellitus (T2DM)  

Regulation of Glucose Metabolism: Key features of T2DM include insulin resistance, insufficient insulin secretion, and elevated blood glucose. Studies suggest that Kisspeptin may regulate glucose metabolism through multiple pathways. On one hand, Kisspeptin can influence insulin sensitivity; on the other hand, it may act on pancreatic islet β-cell function to affect insulin secretion.  

Kisspeptin and Obesity  

Regulation of Energy Balance and Food Intake: Obesity is often associated with energy imbalance due to excessive energy intake and reduced energy expenditure. Kisspeptin regulates energy balance and feeding behavior in the central nervous system. Increased Kisspeptin expression may reduce food intake in animals, while decreased expression may increase it, indicating that Kisspeptin serves as a key regulator of energy intake in the pathogenesis of obesity.  

Kisspeptin and Non-Alcoholic Fatty Liver Disease (NAFLD)  

Effects on Hepatic Metabolism: NAFLD is a liver disease closely linked to insulin resistance and metabolic syndrome, characterized by excessive hepatic fat deposition. Kisspeptin participates in hepatic metabolic regulation. In animal experiments, Kisspeptin intervention has been shown to alter lipid metabolism, inflammatory responses, and oxidative stress in the liver. It may reduce hepatic fat accumulation by regulating the activity of key enzymes involved in fatty acid synthesis and breakdown. Additionally, Kisspeptin may modulate hepatic inflammatory signaling pathways to alleviate inflammation and slow NAFLD progression.  

Kisspeptin and Polycystic Ovary Syndrome (PCOS)  

Dual Regulation of Reproductive Endocrinology and Metabolism: PCOS is a common endocrine and metabolic disorder characterized by both reproductive endocrine abnormalities and glucose-lipid metabolic disorders in most patients. Kisspeptin plays a critical role in PCOS pathogenesis. Centrally, it regulates the hypothalamic-pituitary-gonadal axis to influence reproductive endocrinology in PCOS patients. Meanwhile, it participates in metabolic processes involving insulin, leptin, and adiponectin, suggesting it is a key factor in metabolic dysfunction in PCOS.  

What are the applications of Kisspeptin?  

Treatment of Reproductive System Disorders  

Abnormal Pubertal Development: Kisspeptin is critical for puberty initiation. Studies show that mutations in the Kisspeptin-GPR54 system can lead to delayed puberty or hypogonadism. Exogenous administration of Kisspeptin can stimulate the HPG axis to promote GnRH and gonadotropin secretion, holding promise for treating pubertal development disorders. For example, in patients with hypogonadism due to Kisspeptin signaling defects, supplementation with Kisspeptin or its analogs can restore normal pubertal development ^{[4, 5]}.  

Ovulation Disorders: In the female reproductive system, Kisspeptin regulates the menstrual cycle and ovulation. It has potential therapeutic value for ovulation disorders such as PCOS. By regulating GnRH pulsatile secretion, Kisspeptin can modulate gonadotropin release to improve follicular development and ovulation. Clinical studies show that Kisspeptin induces a more physiological gonadotropin secretion pattern in some ovulation disorder patients, enhancing ovulation success rates^{[5, 6]}.  

Functional Hypothalamic Amenorrhea (FHA): FHA is caused by abnormal GnRH pulsatile secretion in the hypothalamus. As an upstream regulator of GnRH, Kisspeptin is critical for FHA treatment. Studies show that administration of Kisspeptin-54 to FHA patients effectively stimulates gonadotropin (FSH, LH) secretion, holding promise for restoring menstrual cycles and fertility. This provides new strategies for FHA treatment ^[6].  

Treatment of Metabolic Diseases  

Non-Alcoholic Fatty Liver Disease (NAFLD): Recent studies have found that activating the Kisspeptin 1 receptor (KISS1R) signaling pathway has therapeutic effects on NAFLD. In high-fat diet-fed mouse models, knockout of hepatic Kiss1r exacerbates hepatic steatosis, while enhanced KISS1R stimulation protects wild-type mice from steatosis and reduces hepatic fibrosis in diet-induced non-alcoholic steatohepatitis (NASH) mice. Mechanistic studies show that hepatic KISS1R signaling improves NAFLD progression by activating AMPK, a key energy regulatory molecule, to reduce lipogenesis. Additionally, increased hepatic KISS1/KISS1R expression and plasma Kisspeptin levels in NAFLD patients and high-fat diet-fed mice suggest a compensatory mechanism to reduce triglyceride synthesis, making KISS1R a promising new target for NASH treatment ^[7].  

Osteoporosis Treatment: Osteoporosis is a common metabolic bone disease where reproductive hormones play a key role in bone growth and mass maintenance. Studies show that Kisspeptin stimulates osteoblast differentiation and inhibits osteoclasts, offering clinical potential for osteoporosis treatment. The mechanism may involve regulating bone metabolism-related signaling pathways, such as the Wnt pathway and RANKL-OPG system, to promote bone formation, inhibit bone resorption, increase bone density, and improve skeletal health in osteoporosis patients.  

Conclusion 

Although clinical research on Kisspeptin in metabolic disease treatment has made progress, its effects involve multiple aspects including glucose metabolism, energy balance, hepatic metabolism, and dual regulation of reproductive endocrinology and metabolism.

Relevant Citations

[1]    Mills E, O'Byrne K T, Comninos A N. Kisspeptin as a Behavioral Hormone[J]. Seminars in Reproductive Medicine, 2019,37(2):56-63.DOI:10.1055/s-0039-3400239.

[2]    Han S Y, Morris P G, Kim J C, et al. Mechanism of kisspeptin neuron synchronization for pulsatile hormone secretion in  male mice[J]. Cell Reports, 2023,42(1):111914.DOI:10.1016/j.celrep.2022.111914.

[3]    Morris P G, Herbison A E. Mechanism of Arcuate Kisspeptin Neuron Synchronization in Acute Brain Slices From Female Mice[J]. Endocrinology, 2023,164(12).DOI:10.1210/endocr/bqad167.

[4]    Sharma A. Scope of Kisspeptin in Neuroendocrine Disorder[J]. 2023. DOI:10.1093/humupd/dmu009.

[5]    Tsoutsouki J, Abbara A, Dhillo W. Novel therapeutic avenues for kisspeptin[J]. Current Opinion in Pharmacology, 2022,67:102319.DOI:10.1016/j.coph.2022.102319.

[6]    Podfigurna A, Czyzyk A, Szeliga A, et al. Kisspeptin Role in Functional Hypothalamic Amenorrhea[M]//Berga S L, Genazzani A R, Naftolin F, et al. Menstrual Cycle Related Disorders: Volume 7: Frontiers in Gynecological Endocrinology. Cham: Springer International Publishing, 2019:27-42.DOI: 10.1007/978-3-030-14358-9_3.

[7]    Guzman S, Dragan M, Kwon H, et al. Targeting hepatic kisspeptin receptor ameliorates nonalcoholic fatty liver  disease in a mouse model[J]. Journal of Clinical Investigation, 2022,132(10).DOI:10.1172/JCI145889.