Circulating ghrelin exists in both lipoprotein bound and free forms.
BACKGROUND
Ghrelin is a gastric peptide that has been implicated in the development of obesity and cardiovascular disease. It has been reported that ghrelin binds to lipoproteins, although the different binding patterns of acylated ghrelin (AG) and unacylated ghrelin (UAG) are still to be determined.


METHODS
Lipoprotein fractions were generated using a self-generating iodixanol gradient. AG and UAG were measured using specific enzyme immunoassays.


RESULTS
AG bound to all lipoproteins in approximately equal concentrations (VLDL 26%, LDL 22%, HDL 23%) and was present as a plasma protein (27%). UAG bound more specifically to HDL (49%) and was present as a plasma protein (48%).


CONCLUSIONS
The different binding patterns of AG and UAG may have significant implications for their biological effects, including roles in energy metabolism, the development of obesity and potentially in the modulation of cardiovascular disease.
Department of Clinical Biochemistry and Metabolic Medicine, Royal Liverpool University Hospital, UK. lizholmes@hotmail.co.uk
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D000215:Acylation; D000368:Aged; D000369:Aged, 80 and over; D002624:Chemistry, Clinical / Q000379:methods*; D005260:Female; D054439:Ghrelin / Q000097:blood* / Q000737:chemistry; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008074:Lipoproteins / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D014283:Triiodobenzoic Acids / Q000737:chemistry
D054439:Ghrelin; D008074:Lipoproteins; D014283:Triiodobenzoic Acids; C044834:iodixanol