CONTEXT: Ghrelin, an endogenous ligand for the GH secretagogue receptor, is an orexigenic peptide hormone produced primarily by the stomach. Recent studies suggest significant differences in the specificity of currently available ghrelin assays. OBJECTIVE: The aim of the study was to compare four ghrelin assays (two commercially available and two developed by our group) of differing specificity, each used on the same set of more than 800 plasma samples from a human study. DESIGN: Thirteen volunteers were sampled every 20 min for 6 h after consumption of one of three isocaloric drinks consisting of either 80% fat, 80% carbohydrate, or 80% protein. The samples were assayed by RIA for total and active ghrelin, as well as by sandwich assays for acyl and des-acyl ghrelin. The ghrelin profiles for each individual were smoothed using a statistical algorithm to lessen the effects of pulsatility and noise. RESULTS: The sandwich assays for acyl and des-acyl ghrelin yielded ghrelin values that were lower than those from the corresponding RIAs. The ghrelin profiles after nutrient ingestion were similar, yet key differences among the four assays were apparent; in particular, percentage changes were significantly greater in the sandwich assays. CONCLUSIONS: The lower levels and greater relative changes in ghrelin values reported by the sandwich assays are consistent with greater assay specificity. When applied to the nutrient study, the sandwich assays were better able to distinguish the different responses to different nutrients than were the RIAs.
CONTEXT: Ghrelin, an endogenous ligand for the GH secretagogue receptor, is an orexigenic peptide hormone produced primarily by the stomach. Recent studies suggest significant differences in the specificity of currently available ghrelin assays. OBJECTIVE: The aim of the study was to compare four ghrelin assays (two commercially available and two developed by our group) of differing specificity, each used on the same set of more than 800 plasma samples from a human study. DESIGN: Thirteen volunteers were sampled every 20 min for 6 h after consumption of one of three isocaloric drinks consisting of either 80% fat, 80% carbohydrate, or 80% protein. The samples were assayed by RIA for total and active ghrelin, as well as by sandwich assays for acyl and des-acyl ghrelin. The ghrelin profiles for each individual were smoothed using a statistical algorithm to lessen the effects of pulsatility and noise. RESULTS: The sandwich assays for acyl and des-acyl ghrelin yielded ghrelin values that were lower than those from the corresponding RIAs. The ghrelin profiles after nutrient ingestion were similar, yet key differences among the four assays were apparent; in particular, percentage changes were significantly greater in the sandwich assays. CONCLUSIONS: The lower levels and greater relative changes in ghrelin values reported by the sandwich assays are consistent with greater assay specificity. When applied to the nutrient study, the sandwich assays were better able to distinguish the different responses to different nutrients than were the RIAs.
Authors: Nicholas J Beaumont; Vernon O Skinner; Tricia M-M Tan; Bala S Ramesh; Dominic J Byrne; Gavin S MacColl; Jeff N Keen; Pierre M Bouloux; Dimitri P Mikhailidis; K Richard Bruckdorfer; Mark P Vanderpump; Kaila S Srai Journal: J Biol Chem Date: 2003-01-16 Impact factor: 5.157
Authors: S R Nussbaum; R J Zahradnik; J R Lavigne; G L Brennan; K Nozawa-Ung; L Y Kim; H T Keutmann; C A Wang; J T Potts; G V Segre Journal: Clin Chem Date: 1987-08 Impact factor: 8.327
Authors: Garland A Campbell; James T Patrie; Bruce D Gaylinn; Michael O Thorner; Warren K Bolton Journal: Nephrol Dial Transplant Date: 2018-03-01 Impact factor: 5.992
Authors: Robert E Steinert; Christine Feinle-Bisset; Lori Asarian; Michael Horowitz; Christoph Beglinger; Nori Geary Journal: Physiol Rev Date: 2017-01 Impact factor: 37.312
Authors: Rohit K Gupta; Tamil Kuppusamy; James T Patrie; Bruce Gaylinn; Jianhua Liu; Michael O Thorner; Warren K Bolton Journal: Clin J Am Soc Nephrol Date: 2013-06-06 Impact factor: 8.237