Ghrelin Improved Heart Function and Prevented Muscle Wasting in Rats with Heart Failure | Research

The takeaway

Three weeks of ghrelin injections improved cardiac output by 18%, enhanced heart contraction strength, prevented cardiac remodeling, and reversed cachexia in rats with chronic heart failure.

+18% cardiac output
Ghrelin-treated heart failure rats had 18% higher cardiac output than placebo-treated rats after just 3 weeks of treatment

What the researchers found

Three weeks of twice-daily ghrelin injections improved multiple measures of heart function in rats with heart failure caused by coronary artery ligation. Ghrelin-treated heart failure rats had significantly higher cardiac output (315 vs 266 mL/min/kg, P<0.05), stronger heart contractions (dP/dtmax 5,738 vs 4,363 mmHg/s, P<0.05), and improved fractional shortening (19% vs 15%, P<0.05) compared to placebo-treated heart failure rats.

Ghrelin also attenuated cardiac cachexia — the dangerous muscle wasting that accompanies heart failure. Treated rats gained 10% body weight versus only 3% for placebo. Additionally, ghrelin inhibited left ventricular enlargement (remodeling) and increased the thickness of surviving heart muscle. These benefits occurred alongside significantly elevated growth hormone and IGF-1 levels.

Why it matters

This 2001 Circulation paper is one of the earliest and most influential studies demonstrating ghrelin's cardioprotective effects. Published just two years after ghrelin's discovery, it showed that the hunger hormone does far more than stimulate appetite — it directly improves failing heart function and prevents the muscle wasting that kills many heart failure patients. The results were published in Circulation, one of the top cardiology journals, and launched an entire research field exploring ghrelin-based cardiac therapies.

The numbers in context

100 μg/kg SC twice daily · 3 weeks · cardiac output 315 vs 266 mL/min/kg (P<.05) · dP/dtmax 5,738 vs 4,363 mmHg/s (P<.05) · fractional shortening 19% vs 15% (P<.05) · body weight +10% vs +3% (P<.05) · GH and IGF-1 significantly elevated

How the study worked

Rats underwent left coronary artery ligation or sham surgery. Four weeks after surgery (allowing heart failure to develop), rats received rat ghrelin (100 μg/kg subcutaneously twice daily) or saline for 3 weeks. Assessment included echocardiography, cardiac catheterization for hemodynamic measurements, serum GH and IGF-1 levels, and body weight monitoring.

Who was studied

Wistar rats with chronic heart failure induced by left coronary artery ligation

What this study cannot tell us

This is a rat study using surgically-induced heart failure (coronary ligation), which models post-infarction cardiomyopathy but may not represent all forms of human heart failure. The 3-week treatment period is short. Ghrelin's effects may be partly mediated through GH/IGF-1 elevation, which raises theoretical long-term safety concerns. The twice-daily injection regimen would be impractical for clinical use without longer-acting formulations. Specific group sizes are not provided in the abstract.

How to read the evidence

Published in Circulation — the top cardiology journal — this is a well-designed preclinical study with clear hemodynamic endpoints. The 'Moderate' grade reflects the strong methodology and prestigious publication tempered by the animal model context.

When this study was published

Published in 2001, this is a foundational study that launched the field of ghrelin-cardiac research. Despite being over two decades old, it remains heavily cited and its core findings have been supported by subsequent studies in both animals and small human trials.

The bigger picture

This Circulation paper was groundbreaking — published just two years after ghrelin was discovered in 1999, it demonstrated that the hunger hormone has profound cardiac effects. It launched a research field that has since explored ghrelin and its analogs for heart failure, cardiac surgery recovery, and cachexia. The dual benefit of improving heart function while preventing muscle wasting addresses two of the most devastating aspects of heart failure simultaneously.

Questions still open

Are ghrelin's cardiac benefits primarily mediated through GH/IGF-1 elevation, or through direct cardiac effects?
Has ghrelin been tested in human heart failure patients, and do the hemodynamic improvements translate?
Could a long-acting ghrelin analog provide sustained cardiac benefits without the need for twice-daily injections?

Common questions

What is cardiac cachexia and why is it so dangerous?

Cardiac cachexia is severe muscle wasting that occurs in advanced heart failure. The failing heart triggers inflammatory and hormonal changes that break down muscle tissue throughout the body, causing dramatic weight loss and weakness. It's extremely dangerous — heart failure patients who develop cachexia have roughly double the mortality rate. The fact that ghrelin prevented this wasting while also improving heart function makes it a uniquely attractive therapeutic candidate.

Has ghrelin been tested in humans with heart failure?

Yes, but only in small studies. Several clinical trials have shown that intravenous ghrelin infusion acutely improves cardiac output, exercise capacity, and muscle strength in heart failure patients. However, no large randomized trials have been completed, and no ghrelin-based therapy is approved for heart failure. This animal study from 2001 provided the scientific foundation for those human studies.

Read the original research

Chronic administration of ghrelin improves left ventricular dysfunction and attenuates development of cardiac cachexia in rats with heart failure.

Circulation, 104(12), 1430-5

View on PubMed ↗

Citation

Nagaya, N; Uematsu, M; Kojima, M; Ikeda, Y; Yoshihara, F; Shimizu, W; Hosoda, H; Hirota, Y; Ishida, H; Mori, H; Kangawa, K. (2001). Chronic administration of ghrelin improves left ventricular dysfunction and attenuates development of cardiac cachexia in rats with heart failure.. Circulation, 104(12), 1430-5.