Ghrelin, a novel 28 amino acid peptide found in hypothalamus and stomach, was recently identified as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). We have now found that both intracerebroventricular (ICV) and intraperitoneal (i.p.) administration of ghrelin in freely feeding rats stimulated food intake. The onset of increased feeding was rapid and after ICV administration was sustained for 24 hours. Following ICV administration of 3nmol ghrelin, the duration and magnitude of the feeding stimulation was similar to that following 5nmol neuropeptide Y (NPY). Plasma growth hormone (GH) concentration increased following both ICV and i.p. administration of ghrelin. Release of adrenocorticotrophic hormone (ACTH) was stimulated and thyroid stimulating hormone (TSH) inhibited following ICV administration of ghrelin. These data suggest a possible role for the newly identified endogenous hypothalamic peptide, ghrelin, in stimulation of feeding and growth hormone secretion.
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