scholarly journals LEAP-2: An Emerging Endogenous Ghrelin Receptor Antagonist in the Pathophysiology of Obesity

2021 ◽  
Vol 12 ◽  
Author(s):  
Xuehan Lu ◽  
Lili Huang ◽  
Zhengxiang Huang ◽  
Dandan Feng ◽  
Richard J. Clark ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Energy Balance ◽  
Food Intake ◽  
Antimicrobial Peptide ◽  
Molar Ratio ◽  
Positive Energy ◽  
Energy Status ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Ghrelin Receptor

Liver-expressed antimicrobial peptide 2 (LEAP-2), originally described as an antimicrobial peptide, has recently been recognized as an endogenous blocker of growth hormone secretagogue receptor 1a (GHS-R1a). GHS-R1a, also known as ghrelin receptor, is a G protein-coupled receptor (GPCR) widely distributed on the hypothalamus and pituitary gland where it exerts its major functions of regulating appetite and growth hormone (GH) secretion. The activity of GHS-R1a is controlled by two counter-regulatory endogenous ligands: Ghrelin (activation) and LEAP-2 (inhibition). Ghrelin activates GHS-R1a on the neuropeptide Y/Agouti-related protein (NPY/AgRP) neurons at the arcuate nucleus (ARC) to promote appetite, and on the pituitary somatotrophs to stimulate GH release. On the flip side, LEAP-2, acts both as an endogenous competitive antagonist of ghrelin and an inverse agonist of constitutive GHS-R1a activity. Such a biological property of LEAP-2 vigorously blocks ghrelin’s effects on food intake and hormonal secretion. In circulation, LEAP-2 displays an inverse pattern as to ghrelin; it increases with food intake and obesity (positive energy balance), whereas decreases upon fasting and weight loss (negative energy balance). Thus, the LEAP-2/ghrelin molar ratio fluctuates in response to energy status and modulation of this ratio conversely influences energy intake. Inhibiting ghrelin’s activity has shown beneficial effects on obesity in preclinical experiments, which sheds light on LEAP-2’s anti-obesity potential. In this review, we will analyze LEAP-2’s effects from a metabolic point of view with a focus on metabolic hormones (e.g., ghrelin, GH, and insulin), and discuss LEAP-2’s potential as a promising therapeutic target for obesity.

scholarly journals Evidence Supporting a Role for Constitutive Ghrelin Receptor Signaling in Fasting-Induced Hyperphagia in Male Mice

Endocrinology ◽  
2017 ◽  
Vol 159 (2) ◽  
pp. 1021-1034 ◽  
Author(s):  
Gimena Fernandez ◽  
Agustina Cabral ◽  
María F Andreoli ◽  
Alexandra Labarthe ◽  
Céline M'Kadmi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Peptide Hormone ◽  
Negative Energy ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Ghrelin Receptor ◽  
Orexigenic Peptide ◽  
Hypothalamic Arcuate Nucleus

Abstract Ghrelin is a potent orexigenic peptide hormone that acts through the growth hormone secretagogue receptor (GHSR), a G protein–coupled receptor highly expressed in the hypothalamus. In vitro studies have shown that GHSR displays a high constitutive activity, whose physiological relevance is uncertain. As GHSR gene expression in the hypothalamus is known to increase in fasting conditions, we tested the hypothesis that constitutive GHSR activity at the hypothalamic level drives the fasting-induced hyperphagia. We found that refed wild-type (WT) mice displayed a robust hyperphagia that continued for 5 days after refeeding and changed their food intake daily pattern. Fasted WT mice showed an increase in plasma ghrelin levels, as well as in GHSR expression levels and ghrelin binding sites in the hypothalamic arcuate nucleus. When fasting-refeeding responses were evaluated in ghrelin- or GHSR-deficient mice, only the latter displayed an ∼15% smaller hyperphagia, compared with WT mice. Finally, fasting-induced hyperphagia of WT mice was significantly smaller in mice centrally treated with the GHSR inverse agonist K-(D-1-Nal)-FwLL-NH2, compared with mice treated with vehicle, whereas it was unaffected in mice centrally treated with the GHSR antagonists D-Lys3-growth hormone–releasing peptide 6 or JMV2959. Taken together, genetic models and pharmacological results support the notion that constitutive GHSR activity modulates the magnitude of the compensatory hyperphagia triggered by fasting. Thus, the hypothalamic GHSR signaling system could affect the set point of daily food intake, independently of plasma ghrelin levels, in situations of negative energy balance.

scholarly journals Intraportal Infusion of Ghrelin Could Inhibit Glucose-Stimulated GLP-1 Secretion by Enteric Neural Net in Wistar Rat

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xiyao Zhang ◽  
Wensong Li ◽  
Ping Li ◽  
Manli Chang ◽  
Xu Huang ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Portal Vein ◽  
Wistar Rat ◽  
Inhibitory Effect ◽  
Neural Net ◽  
Incretin Effect ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Intraportal Infusion

As a regulator of food intake and energy metabolism, the role of ghrelin in glucose metabolism is still not fully understood. In this study, we determined the in vivo effect of ghrelin on incretin effect. We demonstrated that ghrelin inhibited the glucose-stimulated release of glucagon-like peptide-1 (GLP-1) when infused into the portal vein of Wistar rat. Hepatic vagotomy diminished the inhibitory effect of ghrelin on glucose-stimulated GLP-1 secretion. In addition, phentolamine, a nonselective α receptor antagonist, could recover the decrease of GLP-1 release induced by ghrelin infusion. Pralmorelin (an artificial growth hormone release peptide) infusion into the portal vein could also inhibit the glucose-stimulated release of GLP-1. And growth hormone secretagogue receptor antagonist, [D-lys3]-GHRP-6, infusion showed comparable increases of glucose stimulated GLP-1 release compared to ghrelin infusion into the portal vein. The data showed that intraportal infusion of ghrelin exerted an inhibitory effect on GLP-1 secretion through growth hormone secretagogue receptor 1α (GHS1α receptor), which indicated that the downregulation of ghrelin secretion after food intake was necessary for incretin effect. Furthermore, our results suggested that the enteric neural net involved hepatic vagal nerve and sympathetic nerve mediated inhibition effect of ghrelin on incretin effect.

scholarly journals Assessing the role of the growth hormone secretagogue receptor in motivational learning and food intake.

2009 ◽  
Vol 123 (5) ◽  
pp. 1058-1065 ◽  
Author(s):  
Alexander W. Johnson ◽  
Rebecca Canter ◽  
Michela Gallagher ◽  
Peter C. Holland
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue

scholarly journals Long-term effects of ghrelin and ghrelin receptor agonists on energy balance in rats

2008 ◽  
Vol 295 (1) ◽  
pp. E78-E84 ◽  
Author(s):  
Sabine Strassburg ◽  
Stefan D. Anker ◽  
Tamara R. Castaneda ◽  
Lukas Burget ◽  
Diego Perez-Tilve ◽  
...  
Keyword(s):  
Body Weight ◽  
Energy Balance ◽  
Food Intake ◽  
Energy Expenditure ◽  
Therapeutic Potential ◽  
Body Weight Gain ◽  
Metabolic Effects ◽  
Positive Energy ◽  
High Dose ◽  
Growth Hormone Secretagogue

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), is the only circulating agent to powerfully promote a positive energy balance. Such action is mediated predominantly by central nervous system pathways controlling food intake, energy expenditure, and nutrient partitioning. The ghrelin pathway may therefore offer therapeutic potential for the treatment of catabolic states. However, the potency of the endogenous hormone ghrelin is limited due to a short half-life and the fragility of its bioactivity ensuring acylation at serine 3. Therefore, we tested the metabolic effects of two recently generated GHS-R agonists, BIM-28125 and BIM-28131, compared with ghrelin. All agents were administered continuously for 1 mo in doses of 50 and 500 nmol·kg−1·day−1 using implanted subcutaneous minipumps in rats. High-dose treatment with single agonists or ghrelin increased body weight gain by promoting fat mass, whereas BIM-28131 was the only one also increasing lean mass significantly. Food intake increased during treatment with BIM-28131 or ghrelin, whereas no effects on energy expenditure were detected. With the lower dose, only BIM-28131 had a significant effect on body weight. This also held true when the compound was administered by subcutaneous injection three times/day. No symptoms or signs of undesired effects were observed in any of the studies or treated groups. These results characterize BIM-28131 as a promising GHS-R agonist with an attractive action profile for the treatment of catabolic disease states such as cachexia.

scholarly journals Genetic Linkage and Association of the Growth Hormone Secretagogue Receptor (Ghrelin Receptor) Gene in Human Obesity

Diabetes ◽  
2004 ◽  
Vol 54 (1) ◽  
pp. 259-267 ◽  
Author(s):  
A. Baessler ◽  
M. J. Hasinoff ◽  
M. Fischer ◽  
W. Reinhard ◽  
G. E. Sonnenberg ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Genetic Linkage ◽  
Receptor Gene ◽  
Human Obesity ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Ghrelin Receptor

Effect of chronic hyperghrelinemia on ingestive action of ghrelin

2006 ◽  
Vol 290 (3) ◽  
pp. R803-R808 ◽  
Author(s):  
Wei Wei ◽  
Xiang Qi ◽  
Jason Reed ◽  
Jeff Ceci ◽  
Hui-Qun Wang ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Transgenic Mice ◽  
Growth Response ◽  
Fat Pad ◽  
Endogenous Ligand ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Gh Secretion ◽  
Ghrelin Gene

The stomach hormone ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). Systemic administration of ghrelin will cause elevations in growth hormone (GH) secretion, food intake, adiposity, and body growth. Ghrelin also affects insulin secretion, gastric acid secretion, and gastric motility. Several reports indicate that repeated or continuous activation of GHS-R by exogenous GHSs or ghrelin results in a diminished GH secretory response. The purpose of this study was to examine the extent to which the acute stimulation of food intake by exogenous ghrelin is altered by chronic hyperghrelinemia in transgenic mice that overexpress the human ghrelin gene. The present findings show that the orexigenic action of exogenous ghrelin is not diminished by a chronic hyperghrelinemia and indicate that the food ingestive pathway of the GHS-R is not susceptible to desensitization. In contrast, the epididymal fat pad growth response, like the GH response, to exogenous ghrelin is blunted in ghrelin transgenic mice with chronic hyperghrelinemia.

scholarly journals Recent Advances in Potential Clinical Application of Ghrelin in Obesity

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Christine Delporte
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Biological Effects ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Taste Receptor ◽  
Molecular Targets ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Amino Acid Peptide

Ghrelin is the natural ligand of the growth hormone secretagogue receptor (GHS-R1a). Ghrelin is a 28 amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by ghrelinO-acyltransferase (GOAT). Ghrelin stimulates growth hormone secretion, but also appetite, food intake, weight gain, and gastric emptying. Ghrelin is involved in weight regulation, obesity, type 2 diabetes, and metabolic syndrome. Furthermore, a better understanding of ghrelin biology led to the identification of molecular targets modulating ghrelin levels and/or its biological effects: GOAT, ghrelin, and GHS-R1a. Furthermore, a recent discovery, showing the involvement of bitter taste receptor T2R in ghrelin secretion and/or synthesis and food intake, suggested that T2R could represent an additional interesting molecular target. Several classes of ghrelin-related pharmacological tools for the treatment of obesity have been or could be developed to modulate the identified molecular targets.

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