Ghrelin
- OMIM: 605353
- UniProt: Q9UBU3
- MGI: 1930008
Ghrelin (acronym, Eng. Inducing Growth Hormone Release " growth hormone release in the introduction ") is an appetite- stimulating hormone, which is produced in the gastric mucosa. In addition to appetite stimulation, the hormone has a number of other effects.
Education
It is mainly produced in the parietal cells in the epithelium of the gastric fundus, but also in the pancreas and converted into a precursor in the hypothalamus and the pituitary gland and by elimination of some amino acids in the active form.
Structure
Ghrelin is a peptide hormone consisting of 28 amino acids, which by post-translational modification of the precursor protein Preproghrelin (117 amino acids) is formed. Same time, a molecule Obestatin. The third amino acid serine of ghrelin is esterified with octanoic acid. This modification is essential for the effect of the hormone. The molecular mass of the precursor is 12.91 kDa, that of ghrelin 3.24 kDa.
Physiology
Ghrelin is a hormone that regulates food intake and growth hormone secretion. Maybe it plays a role in the development of obesity. In periods of starvation, the ghrelin level rises in the blood after eating it drops. Sleep deprivation induces increased ghrelin secretion and contributes in this way probably to the development of obesity.
Effects
Hunger
In the experiment, increase ghrelin infusions food intake. In the fasting state the Ghrelinausschüttung is increased after eating the ghrelin decreases.
It stimulates the secretion of the neuropeptide Y, which is known, that it increases the food intake and of Agouti -related peptide hormones ( AGRP ) in the arcuate nucleus.
- See also: More hormones control the hunger or satiety next ghrelin and leptin and cortisol.
Alleviation of depression
In addition, ghrelin acts in the mouse experimental anxiolytic. A Texas study from 2008 suggests the antidepressant effect of ghrelin, and illuminates the question of why chronic stress and depression can lead to obesity.
Associated with alcohol dependence
The hypothesis that ghrelin is responsible for the development of alcohol dependence was also confirmed in mouse experiments.
Growth hormone
Ghrelin is an endogenous ligand for a receptor that regulates the release of growth hormone in the pituitary. On special cells of the anterior pituitary ( acidophilic cells) it binds to the GHS receptor ( growth hormone secretagogue receptor ) and thus stimulates the release of growth hormone on.
Pathophysiology
The rare Prader -Willi syndrome is partially massively increased ghrelin levels. It is characterized by a lack of satiety.