Gut hormones play a significant role in regulating feeding and energy balance. Almost all the gut hormones are responsible for reducing appetite i.e. they are anorectic, except for ghrelin which is responsible for increasing the appetite i.e. it has an orexigenic effect. Ghrelin is a 28-amino acid bioactive peptide hormone that was isolated from the stomach in 1999 by Kojima et al. A natural endogenous ligand of the growth hormone (GH) secretagogue receptor, it helps in the regulation of glucose and fat metabolism and regulation of energy balance. It also plays an essential role in regulation of appetite and bodyweight as well as modulation of gastrointestinal functions. The electronic databases, like CENTRAL, DARE, CDSR, Cochrane Methodology Reviews, MEDLINE, PUBMED and other resources. hard copies and unpublished works were searched. Pubmed keyword strategy was tailored to the other databases. The previous studies points out that Ghrelin is a hormone and the only known circulating orexigen produced in response to hunger. Although many substances play a role in the control of appetite, ghrelin is the only known peptide which increases appetite by sending signals of starvation from a stomach to the central nervous system. Besides playing a role in short-term regulation of food intake, ghrelin might also play a role in long-term regulation of energy balance. It also shows effects on the reward and motivation centers in the brain regions. Ghrelin has diverse roles. It also plays an essential role in regulation of appetite and bodyweight as well as modulation of gastrointestinal functions. As ghrelin is disturbed in obesity, it is important to reveal the mechanism of action for the purpose of developing novel therapeutic interventions.
Key words: Obesity; Orexigenic; Ghrelin; Energy Balance; Leptin
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