GHRH and its analog MR-409 reversed pathological heart enlargement and improved heart function in pressure-overloaded mice, revealing a new therapeutic role for this peptide hormone in heart failure.
Reversed cardiac hypertrophy in vivoThe GHRH agonist MR-409 mitigated cardiac hypertrophy in mice with pressure-overloaded hearts, improving cardiac function and restoring normal cardiomyocyte contractility and sarcolemmal structure — demonstrating therapeutic potential beyond growth hormone regulation.
What the researchers found
GHRH and its agonistic analog MR-409 attenuated cardiac hypertrophy both in vitro and in vivo. In cell models (H9c2 cardiac cells, adult rat ventricular myocytes, and human iPSC-derived cardiomyocytes), GHRH reduced phenylephrine-induced hypertrophy by blocking Gq signaling and its downstream components (phospholipase Cβ, PKCε, calcineurin, phospholamban) while activating Gαs/cAMP/PKA and inhibiting Epac1. In vivo, MR-409 mitigated cardiac hypertrophy in mice with pressure overload from transverse aortic constriction, improved cardiac function, and restored cardiomyocyte contractility and sarcolemmal structure.
Why it matters
Heart failure caused by pathological cardiac hypertrophy is a leading cause of death worldwide with limited therapeutic options. This study, published in PNAS, identifies GHRH as a previously unknown anti-hypertrophic regulator of the heart and demonstrates that GHRH analogs could be repurposed as treatments for heart failure — a potential new application for a well-characterized peptide hormone class.
How the study worked
Multi-level approach: in vitro hypertrophy was induced with phenylephrine in three cell types (H9c2 cardiac cells, adult rat ventricular myocytes, and human iPSC-derived cardiomyocytes) and treated with GHRH(1-44)NH2. Hypertrophic gene expression and signaling pathways were measured. In vivo, mice underwent transverse aortic constriction (TAC) to create pressure overload, then received the GHRH agonist MR-409. Cardiac function, hypertrophy markers, cardiomyocyte contractility, and sarcolemmal structure were assessed.
Who was studied
In vitro cardiac cell models (including human iPSC-derived cardiomyocytes) and mice with transverse aortic constriction-induced pressure overload
What this study cannot tell us
While the study uses human iPSC-derived cardiomyocytes in vitro, the in vivo work is limited to mice. The TAC model creates acute pressure overload which may not fully replicate the gradual development of heart failure in humans. Long-term safety of GHRH agonists in cardiac patients — including effects on growth hormone levels and potential tumor promotion — is not addressed. The study does not compare MR-409 to existing heart failure treatments.
How to read the evidence
This is a high-quality preclinical study published in PNAS with a comprehensive multi-level approach: three in vitro cell models (including human iPSC-derived cardiomyocytes) and an in vivo mouse model. The detailed mechanistic characterization is a strength. However, clinical translation remains unproven.
When this study was published
Published in 2017 in PNAS, this study established a new paradigm for GHRH's role in cardiac biology. Since then, research into GHRH analogs for cardiovascular applications has continued, though no clinical trials for heart failure have been reported.
The bigger picture
This PNAS study from a team including Andrew Schally (Nobel laureate for GHRH discovery) reveals that GHRH has direct cardioprotective effects independent of growth hormone. This adds heart failure to the growing list of potential therapeutic applications for GHRH analogs, which are already being explored for cancer, diabetes, and inflammation. The identification of specific signaling mechanisms (Gq blockade, cAMP/PKA activation) provides clear targets for drug optimization.
Questions still open
- Can GHRH analogs reverse established cardiac hypertrophy in humans, or are they only effective when given early?
- Would the growth hormone-stimulating effects of GHRH analogs create complications in heart failure patients, many of whom are elderly?
- How does MR-409's cardioprotective efficacy compare to established heart failure drugs like ACE inhibitors and beta-blockers?
Common questions
How is GHRH related to heart function if it's a growth hormone?
Could this lead to a new heart failure drug?
Read the original research
Growth hormone-releasing hormone attenuates cardiac hypertrophy and improves heart function in pressure overload-induced heart failure.
Proceedings of the National Academy of Sciences of the United States of America, 114(45), 12033-12038
Citation
Gesmundo, Iacopo; Miragoli, Michele; Carullo, Pierluigi; Trovato, Letizia; Larcher, Veronica; Di Pasquale, Elisa; Brancaccio, Mara; Mazzola, Marta; Villanova, Tania; Sorge, Matteo; Taliano, Marina; Gallo, Maria Pia; Alloatti, Giuseppe; Penna, Claudia; Hare, Joshua M; Ghigo, Ezio; Schally, Andrew V; Condorelli, Gianluigi; Granata, Riccarda. (2017). Growth hormone-releasing hormone attenuates cardiac hypertrophy and improves heart function in pressure overload-induced heart failure.. Proceedings of the National Academy of Sciences of the United States of America, 114(45), 12033-12038. https://doi.org/10.1073/pnas.1712612114