Hexarelin, a growth hormone-releasing peptide, discloses protectant activity against cardiovascular damage in rats with isolated growth hormone deficiency.
De Gennaro Colonna. V V; Rossoni. G G; Bernareggi. M M; Müller. E E EE; Berti. F F
Key Findings
- Growth‑hormone deficiency in rats leads to impaired cardiac contractility, reduced prostacyclin production, and endothelial dysfunction.
- Hexarelin treatment (80 µg/kg twice daily for 15 days) fully restores GH levels and normalizes heart performance during ischemia‑reperfusion.
- Hexarelin also normalizes vascular responses, including prostacyclin formation, angiotensin II vasopressor activity, and endothelial‑dependent relaxation.
Practical Outcomes
- For biohackers, the study suggests hexarelin might protect heart and blood‑vessel health when GH is low, but the evidence is limited to rats. No human dosing or safety data are provided, so any use should be experimental and approached with caution.
Summary
In rats that lack growth hormone, the heart and blood vessels don’t work well, but giving them the peptide hexarelin for two weeks fixes the hormone levels and restores normal heart and vessel function. This shows hexarelin can reverse damage caused by growth‑hormone deficiency, at least in animals.
Abstract
The ability of hexarelin, a recently synthesized hexapeptide with a remarkable growth hormone (GH)-releasing activity, to reverse signs of cardiovascular dysfunction in GH-deficient animals was studied in young male rats made GH deficient by the administration of an anti-GH-releasing hormone serum (GHRH-Ab) for 20 days. Heart preparations from GHRH-Ab treated rats, subjected to low-flow ischemia and reperfusion, showed: a progressive increase of left ventricular end-diastolic pressure during the ischemic period and a poor recovery of contractility at reperfusion as compared to control hearts; a decreased rate of formation of 6-keto-PGF1 alpha, the stable metabolite of prostacyclin, in perfusates of both preischemic and reperfusion period; an increased vasopressor activity of angiotensin II on the coronary vasculature. The endothelium-dependent relaxing function in GH-deficient rats was also evaluated in aortic ring preparations, which showed: a decreased rate of formation of 6-keto-PGF1 alpha, an hyperreactivity to endothelin-1, a markedly reduced vasopressor response to NG-monomethyl-L-arginine (the nitric oxide synthase inhibitor) and a decreased vasodilator response to acetylcholine of precontracted aortic tissue. Hexarelin (80 micrograms/kg, s.c. twice daily), administered for 15 days to GHRH-Ab-treated rats, fully restored the somatotropic function and reversed all the signs of cardiac and endothelial dysfunction. In fact, in heart preparations from rats treated with hexarelin the trend of the ischemic damage was similar to that observed in control rats and both the rate of formation of 6-keto-PGF1 alpha and the vasopressor activity of angiotensin II were reverted to control levels. Furthermore, all the parameters of endothelial function were in the normal range. These results indicate that GH deficiency in rats is responsible for an impairment of cardiac function that is associated with a damage of the endothelium-dependent relaxing function not limited to coronary vessels but widespread in the circulation. These alterations are fully reverted by an in vivo treatment with hexarelin.
Study Information
pubmed
1997