Study summary · research use only
Structure-activity relationship for peptídic growth hormone secretagogues
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This study investigated structure-activity relationships among growth hormone releasing peptides (GHRPs) built on a common Ala-Trp-(D-Phe)-Lys core, using a radio-competitive binding assay against the GHSR1a receptor and its natural ligand ghrelin (species not specified for this assay). Chemical modifications at positions 1, 2, 3, and 7 of the structure aa-aa-aa-Ala-Trp-(D-Phe)-Lys were reported to affect receptor binding. To assess in vivo relevance, excretion samples were analyzed after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin (species not specified for the excretion studies), and receptor-binding activity from intact GHRPs plus metabolites was detected in the urine. The authors state the results provide structure-activity information relevant to detecting GHSR1a-binding substances, including metabolites, in urine for anti-doping purposes.
Abstract
Growth hormone releasing peptides (GHRPs) could be widely used by cheating athletes because they produce growth hormone (GH) secretion, so may generate an ergogenic effect in the body. Knowledge of the essential amino acids needed in GHRP structure for interaction with the target biological receptor GHSR1a, the absorption through different administration routes, and the maintenance of pharmacological activity of potential biotransformation products may help in the fight against their abuse in sport. Several GHRPs and truncated analogues with the common core Ala-Trp-(D-Phe)-Lys have been studied with a radio-competitive assay for the GHSR1a receptor against the radioactive natural ligand ghrelin. Relevant chemical modifications influencing the activity for positions 1, 2, 3, and 7 based on the structure aa-aa-aa-Ala-Trp-(D-Phe)-Lys have been obtained. To test in vivo the applicability of the activities observed, the receptor assay activity in samples from excretion studies performed after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin was confirmed. Overall results obtained allow to infer structure-activity information for those GHRPs and to detect GHSR1a binding (intact GHRPs plus active metabolites) in excreted urines. Copyright © 2016 John Wiley & Sons, Ltd.
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