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The role of ghrelins Essay Example for Free
The role of ghrelins EssayGhrelin is a general name for a class of hormones set in motion in the gastrointestinal tract of vertebrates. It is a preprohormone containing a chain of 28 amino acid peptides. During synthesis, a modification arises whereas n-octanoic acid is bound to one of its amino acids. This makes it capable of playing its biological role. Ghrelins are synthesized at the fundus lining the stomach. It is primarily produced by epithelial cells lining the fundus. However, smaller amounts have to a fault been detected in the kidneys, placenta, hypothalamus and the pituitary gland. (Brown, 2006)The ghrelin receptor was known before the discovery of ghrelin. It is located in the anterior pituitary and stimulates discrimination of harvest-feast hormone when activated. It was named GHS-R or appendage hormone secretagoue receptor. In 1999, Kojima et al. announced that they have discovered the inhering ligand for GHS-R. They named it ghrelin, deriving it form the word ghre which mode grow in Proto-Indo-European languages. They obtained it from rat stomach and investigated its role in pituitary growth hormone and energy homeostasis functions. (Kojima Kangawa, 2004)Roles of ghrelinGhrelin is the ligand of GHS-r. Its signal together with that of semostatin and other growth hormone inducers accommodate the timing as well as the magnitude of growth hormone excretion. It is suggested that the stomach releases ghrelin into the production linestream, where it is conveyed to the potiuitary gland, triggering the release of growth hormone. Kanagawa et al. found significant amounts of ghrelin in healthy people.(Kojima et al., 1999) In 2000, Ezio Ghigo et al. discovered that ghrelin injections led to prolonged increase of growth hormone concentrations in the blood. (Dickson, 1999) Ghrelin also seems to stimulate appetite. Lab tests in rats show ann increase in soundbox weight after ghrelin injections. This effect is independent of ghrelins role in GH st imulation. In people, a commonplace side effect of taking ghrelin containing drugs was the sensation of intense hunger. About 80% of test participants in a weigh to test ghrelins growth hormone functions also suffered an increase of appetite. It was found that ghrelin concentration in the blood increases as a person grows hungry and decreases as that persons hunger is sated. Another study showed that people injected with ghrelin before meals increased their food intake by 30%. (Cummings et al., 2002)Another study also showed that resting ghrelin levels rise as net body weight decreases and returns once a set point is reached. This means that the body regulates ghrelin levels based on a specific body weight attainment, making you hungrier as you dope off more weight. Persons with anorexia nervosa, a disorder in which people starve themselves show extremely high amounts of ghrelin. exclusively it seems in their cases, their body does not listen. (Travis, 2002)The increase of ghrel ins is also related to time as discovered by Yildiz et al.An increase in ghrelin was noted between midnight to dawn, mhowever, hunger is suppressed by other hormones, making it easier to advert asleep and eat in the morning after.(Yildiz, Suchard, Wong, McCann, Licinio, 2004)Alos, lack of sleep particularly in obese persons head to production of ghrelin and less production of leptin, the hormone which suppresses appetite. Ghrelin levels also decrease dramatically with the conduction of gastric electrical shunt surgery. Animal research has also discovered that ghrelin may enhance memory and learning as it enters the genus Hippocampus via the bloodstream. High ghrelin levels, particularly before meals when the stomach is empty may be the time most conducive to learning. (Philips, 2006)REFERENCESBrown, R. (2006). Ghrelin. Retrieved March 11, 2007, from http//www.vivo.colostate.edu/hbooks/pathphys/endocrine/gi/ghrelin.htmlCummings, D., Weigle, D., Frayo, R., Breen, P., Ma, M., Dellin ger, E., et al. (2002). Plasma Ghrelin Levels after Diet-Induced Weight Loss or Gastric short-circuit Surgery. New England Journal of Medicine(346), 1623-1630.Dickson, S. L. (1999). Ghrelin A newly discovered hormone Electronic Version. British Society for Neuroenterology from http//neuroendo.org.uk/index.php/content/ get/26/11/.Kojima, M., Hosoda, H., Date, Y., Nakazato, M., Matsuo, H., Kangawa, K. (1999). Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 402, 656-660 (402), 656-660.Kojima, M., Kangawa, K. (2004). Ghrelin Structure and FunctionElectronic Version. Physiological Review, 85, 495-522. Retrieved March 11 2007.Philips, M. L. (2006). hurt hormone tied to learning Electronic Version. The Scientist. Retrieved March 11 2007 from http//www.the-scientist.com/news/display/23132/.Travis, J. (2002). The Hunger Hormone? Electronic Version. acquirement News Online, 161, 107. Retrieved March 11 2007 from http//www.sciencenews.org/articles/20020216/bob1 0.asp.Yildiz, B. O., Suchard, M. A., Wong, M.-L., McCann, S. M., Licinio, J. (2004). Alterations in the dynamics of circulating ghrelin, adiponectin, and leptin in human obesity Electronic Version. health check Sciences. Retrieved March 11 2007 from http//www.pubmedcentral.nih.gov/articlerender.fcgi?artid=478601.