Variety of acyl modifications in mammalian ghrelins.

Ghrelin, a 28-amino acid-long peptide with an n-octanoyl modification at Ser(3), has been isolated from rat and human stomachs as an endogenous ligand for the growth hormone secretagogue receptor. It is very important to study the ghrelin from mammals (especially, domestic animals) that serve as human companions, food resources, and model organisms. We purified feline and caprine ghrelin and observed that the administration of synthetic ghrelin increased plasma growth hormone (GH) levels in cats and goats. Therefore, we believe that ghrelin may play important roles in GH release in mammals.