Prandial ghrelin attenuation provides evidence that des-acyl ghrelin may be an artifact of sample handling in human plasma

Abstract

Background: Plasma acyl and des-acyl ghrelin are thought of as components of total ghrelin, but this has never been validated using ex vivo spiking experiments, human sample collection comparisons and fit-for-purpose translatable assays. Results: Acyl ghrelin plasma stability was analyzed by LC–MS/MS and it revealed that acyl ghrelin is enzymatically and chemically converted to des-acyl ghrelin in the presence of active serine proteases and HCl. ELISAs with less than 30% total error were used to assess acyl ghrelin behavior in matched authentic human samples. Acyl and total ghrelin were not statistically different in 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride samples and acyl ghrelin losses in K2EDTA plasma were accounted for in des-acyl ghrelin formation. Conclusion: Acyl ghrelin is total ghrelin and des-acyl ghrelin should not be detectible in healthy human plasma under optimal sample handling and assaying conditions.