Ghrelin (human)

Ghrelin, a 28 aa peptide predominantly produced by the stomach, is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R) that potently stimulates growth hormone release. Studies suggest that peripherally or centrally administrated ghrelin, independent of growth hormone, decreases fat oxidation and increases food intake and adiposity. In addition, plasma ghrelin levels are lower in obese human subjects. Ghrelin promotes the production of orexigenic neuropeptides (neuropeptide Y and agouti-related protein) in the hypothalamic arcuate nuclei and activates the neurons which produce these orexigenic neuropeptides, resulting in an increase in feeding and body weight and thereby opposing the effects of leptin. Moreover, ghrelin shows regulatory effects on the cardiovascular and immune system.