This document discusses the hormone ghrelin. It was discovered in 1999 by Masayasu Kojima and colleagues after discovering the growth hormone secretagogue receptor. Ghrelin is a 28 amino acid polypeptide hormone secreted by the stomach that stimulates appetite and the release of growth hormone. It binds to the GH-secretgogue receptor. Ghrelin levels increase before meals and decrease after eating, influenced by factors like food intake, glucose, lipids, and insulin. Physiologically, ghrelin stimulates growth hormone secretion, increases appetite by acting on the hypothalamus, and increases gastric acid secretion and motility. Potential clinical applications of ghrelin are also mentioned.
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Ghrelin hormone
1. In the name of god
Ghrelin hormone
Navab Ahmadi
2. History of ghrelin
The discovery of ghrelin followed after the discovery of the growth
hormone secretagogue type 1A receptor in 1996 and was reported
by Masayasu Kojima and colleagues(Matsuyama) in 1999
The name is based on its role as a growth hormone-releasing
peptide, with reference to the Proto-Indo-European root ghre,
meaning to grow.(Growth Hormone Release Inducing = Ghrelin)
3. Introduction1
Ghrelin has emerged as the first identified circulating hunger
hormone
Ghrelin is both a hormone in the endocrine system and a
neurotransmitter in the nervous system
28 amino-acid polypeptide
Secreted by oxyntic cell in gastric fundus
Can be found in pancrease, intestine, hypothalamus, pituitary gland
4. Introduction2
Ghrelin is produced mainly by P/D1 cells, lining the fundus of the human stomach,
that contain granules filled with ghrelin
Also by epsilon cells of the pancreas that stimulates hunger
In rodents, X/A-like cells produce ghrelin.
Aside from the stomach and pancreas in adults, ghrelin cells are also found in the
duodenum, jejunum, i leum, and colon, with ghrelin concentration decreasing
from the duodenum to the colon.
5. Structure of ghrelin
28 amino acids
n-octanoyl contacts to third serine from N-terminal (important for
hormone activity)
Bind to GH-secretgogue-receptor 1a (GHS-R1a)
G-protein coupled receptor
6. Factors influencing ghrelin secretion
Most important
Food intake
Ghrelin level increases 1-2 hr prior to meal, max just before eating
and decreases dramatically within 1 hr after meal
Degree of ghrelin level decrease is in proportion with calories and
composition of food (CHO can decrease ghrelin > fat)
Glucose, lipid, amino acid
Ghrelin ↓ in postprandial hypoglycemia or after administration of IV
glucose/fat diet
High protein diet, essential amino acid →↑ ghrelin →↑ GH
(controversial)
13. Other effects of ghrelin
Inhibit proinflammatory cytokin (IL-1, IL-6, TNF)
Increase bone mineral density
Decrease MAP by decreasing peripheral vascular resistance