A new cardiac-specific GHRP receptor was identified that is distinct from the pituitary GH-releasing receptor, explaining how hexarelin protects hearts from ischemic damage independently of growth hormone.
Distinct cardiac receptorThe heart's GHRP receptor is different from the pituitary receptor, meaning cardiac protection is independent of growth hormone release
What the researchers found
A novel cardiac-specific GHRP receptor distinct from the pituitary GHS-R was identified in rat heart tissue, binding hexarelin with high affinity and mediating cardioprotective effects independently of GH release.
Why it matters
The discovery that the heart has its own GHRP receptor means GH secretagogues could be developed specifically for cardiac protection, separate from their GH-releasing effects. This opens a new therapeutic avenue for heart disease.
How the study worked
Animal study using radioligand binding on cardiac membranes from normal, GH-deficient, and senescent rats. Receptor specificity was determined by competition binding with various ligands. Functional cardioprotection was confirmed in isolated heart models.
What this study cannot tell us
Receptor identified in rat hearts; human cardiac receptor confirmation needed. The downstream signaling pathway was not fully characterized. In-vivo cardioprotective dose-response not established.
How to read the evidence
Moderate evidence from comprehensive binding studies with functional validation in isolated heart models, across multiple animal age groups.
When this study was published
Published in 1999. This cardiac GHRP receptor (later linked to CD36) has been further characterized, confirming the heart as a direct target for GH secretagogues.
The bigger picture
Heart disease is the leading cause of death worldwide. A peptide that directly protects the heart through its own receptor — separate from any GH effects — represents a fundamentally new approach to cardiovascular therapy.
Questions still open
- Can this cardiac receptor be targeted with selective peptides for heart protection?
- Does this receptor exist in human hearts?
- Could GHRP analogs be developed that protect the heart without raising GH?
Common questions
Can growth hormone peptides protect the heart?
Could this lead to new heart medications?
Read the original research
Identification and characterization of a new growth hormone-releasing peptide receptor in the heart.
Circulation research, 85(9), 796-802
Citation
Bodart, V; Bouchard, J F; McNicoll, N; Escher, E; Carrière, P; Ghigo, E; Sejlitz, T; Sirois, M G; Lamontagne, D; Ong, H. (1999). Identification and characterization of a new growth hormone-releasing peptide receptor in the heart.. Circulation research, 85(9), 796-802.