Using a novel label-free DMR assay alongside traditional calcium mobilization, researchers systematically characterized ghrelin receptor ligands including the endogenous peptides ghrelin, desacyl-ghrelin, and LEAP2, demonstrating that DMR can distinguish antagonists from inverse agonists — a distinction the calcium assay misses.
12 GHSR ligands profiledMost comprehensive pharmacological comparison of ghrelin receptor ligands to date, revealing that DMR assay detects inverse agonism missed by standard calcium assays
What the researchers found
Ghrelin, anamorelin, HM01, and HM03 behaved as potent full GHSR agonists in both assays. LEAP2(1-14) was identified as a GHSR inverse agonist in DMR but not calcium assays. PF-05190457, HM04, and H1498 acted as inverse agonists in DMR but only antagonists in calcium mobilization, demonstrating DMR's superior ability to discriminate receptor pharmacology.
Why it matters
Understanding the precise pharmacology of ghrelin receptor ligands is critical for developing drugs targeting appetite, cachexia, metabolic disorders, and addiction. This study provides the most comprehensive comparison of GHSR ligands to date and introduces a superior assay method for distinguishing different types of receptor modulation.
The numbers in context
Characterized multiple GHSR ligand types: agonists, antagonists, and inverse agonists using the DMR assay.
How the study worked
In vitro pharmacological characterization using CHO cells expressing human GHSR. Two parallel assays: label-free dynamic mass redistribution (DMR) and calcium mobilization. Tested endogenous peptides (ghrelin, desacyl-ghrelin, LEAP2) and synthetic ligands (anamorelin, HM01, HM03, HM04, YIL-781, PF-05190457, R011, H1498).
Who was studied
In vitro ghrelin receptor ligand characterization
What this study cannot tell us
Entirely in vitro using a single cell line (CHO-GHSR). Pharmacological profiles in recombinant systems may not fully reflect in vivo receptor behavior. No functional outcome data (appetite, GH release) assessed. Patent literature compounds have limited published characterization.
How to read the evidence
Rated preliminary: in vitro pharmacological characterization only. Provides important tool compound data but no clinical or in vivo validation.
When this study was published
Published in 2024. Uses current pharmacological assay technology and includes recently developed compounds.
The bigger picture
The ghrelin system is a major therapeutic target — agonists like anamorelin treat cancer cachexia while inverse agonists are being explored for obesity and addiction. This systematic characterization helps researchers select the right tool compounds and understand the nuances of ghrelin receptor pharmacology.
Questions still open
- Does the distinction between GHSR antagonism and inverse agonism matter for clinical outcomes in patients?
- Could LEAP2-based peptides be developed as therapeutics given their inverse agonist profile?
- How do these pharmacological profiles translate to in vivo effects on appetite and metabolism?
Common questions
What is the ghrelin receptor and why is it important?
What's the difference between a receptor antagonist and an inverse agonist?
Read the original research
In vitro pharmacological characterization of growth hormone secretagogue receptor ligands using the dynamic mass redistribution and calcium mobilization assays.
European journal of pharmacology, 981, 176880
Citation
Sturaro, Chiara; Ruzza, Chiara; Ferrari, Federica; Pola, Pietro; Argentieri, Michela; Frezza, Alessia; Marzola, Erika; Bettegazzi, Barbara; Cattaneo, Stefano; Pietra, Claudio; Malfacini, Davide; Calò, Girolamo. (2024). In vitro pharmacological characterization of growth hormone secretagogue receptor ligands using the dynamic mass redistribution and calcium mobilization assays.. European journal of pharmacology, 981, 176880. https://doi.org/10.1016/j.ejphar.2024.176880