Clinical Significance
Ghrelin levels in the plasma of obese individuals are lower than those in leaner individuals thus suggesting that ghrelin does not contribute to obesity, except in the cases of Prader-Willi syndrome-induced obesity where high ghrelin levels are correlated with increased food intake. Those suffering from the eating disorder anorexia nervosa have high plasma levels of ghrelin compared to both the constitutionally thin and normal-weight controls. One small single-blind study found that intravenous administration of ghrelin to anorexia nervosa patients increased food intake by 12–36% over the trial period.
The level of ghrelin increases during the time of day from midnight to dawn in thinner people which suggests there is a flaw in the circadian system of obese individuals. Short sleep duration may also lead to obesity, through an increase of appetite via hormonal changes. Lack of sleep produces ghrelin, which stimulates appetite and creates less leptin, which, among its many other effects, suppresses appetite.
Ghrelin levels are also high in patients that have cancer-induced cachexia.
At least one study found that gastric bypass surgery not only reduces the gut's capacity for food but also dramatically lowers ghrelin levels compared to both lean controls and those that lost weight through dieting alone.
Ghrelin through its receptor increases the concentration of dopamine in the substantia nigra, a region of the brain where dopamine cell degeneration leads to Parkinson's disease. Hence ghrelin may find application in slowing down the onset of Parkinson's disease.
Read more about this topic: Ghrelin
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