Ghrelin

Ghrelin is a peptide hormone primarily produced by the stomach that functions as a key regulator of appetite, energy balance, and various metabolic processes. It exists in two main forms: acyl-ghrelin (the active form) and des-acyl ghrelin (the predominant circulating form). Ghrelin's most recognized function is stimulating appetite and food intake, earning it the nickname "hunger hormone." Ghrelin levels typically rise before meals when the stomach is empty and decrease after eating. When administered to humans, ghrelin can increase food intake by up to 30%[4][7]. Beyond appetite regulation, ghrelin has numerous other functions. It stimulates growth hormone release from the pituitary gland, inhibits insulin secretion (thereby increasing blood glucose), promotes fat storage, and increases gastric acid secretion and motility[1][4]. Ghrelin also acts on reward-processing regions of the brain such as the amygdala, potentially contributing to food and alcohol addiction behaviors[4][7]. Ghrelin has demonstrated protective effects on multiple organ systems. It shows cardioprotective properties in models of myocardial infarction by promoting vascular network expansion and reducing inflammation[7]. It also exhibits neuroprotective effects, protecting against demyelination and axonal loss in neurological conditions[6]. Therapeutically, ghrelin and ghrelin agonists have shown promise in treating conditions characterized by wasting or appetite loss, such as cachexia, anorexia, and COPD[6][8]. Clinical trials have demonstrated that ghrelin treatment can improve respiratory symptoms, exercise capacity, and quality of life in COPD patients[6]. Additionally, ghrelin may serve as a biomarker for gastrointestinal cancers, with its expression levels correlating with tumor grade and stage in some studies[8]. The ghrelin signaling system represents an important therapeutic target for various conditions related to appetite, metabolism, and organ protection, with ongoing research exploring its potential applications in clinical settings.

Other names

Hunger hormoneLenomorelin (INN)Growth hormone-releasing peptide

Activation of growth hormone secretagogue receptor (GHS-R1a); Stimulation of neuropeptide Y (NPY) and agouti-related protein (AgRP) neurons; Modulation of calcium-mediated pathways in pancreatic beta cells; Activation of cholinergic-dopaminergic reward pathways