GHRH Peptide Tesamorelin Improves Mitochondrial Function in Obese Adults With Low Growth Hormone
In a 12-month double-blind placebo-controlled trial, tesamorelin-induced increases in IGF-I were significantly correlated with improved mitochondrial function (R=0.71, P=0.03) in obese adults with reduced growth hormone secretion.
Quick Facts
What This Study Found
After 12 months, tesamorelin treatment significantly increased IGF-I compared to placebo (change: +102.9 vs +22.8 μg/L; P = 0.02). The key finding was the relationship between IGF-I increases and mitochondrial function:
- Overall correlation between IGF-I increase and phosphocreatine recovery improvement (ViPCr): R = 0.56, P = 0.01
- In tesamorelin-treated subjects only: R = 0.71, P = 0.03 (strong correlation)
- The association remained significant after controlling for age, sex, race, ethnicity, body composition, and insulin sensitivity (all P < 0.05)
Phosphocreatine recovery rate is a validated marker of mitochondrial oxidative capacity, suggesting tesamorelin improves mitochondrial function through IGF-I elevation.
Key Numbers
How They Did This
Double-blind, randomized, placebo-controlled trial over 12 months. 39 obese men and women with reduced GH secretion (confirmed by GHRH-arginine stimulation testing) were randomized to tesamorelin or placebo. Mitochondrial function was assessed using 31P magnetic resonance spectroscopy to measure phosphocreatine recovery after submaximal exercise — a gold-standard noninvasive measure of muscle mitochondrial capacity. IGF-I and body composition were measured at baseline and 12 months.
Why This Research Matters
Mitochondrial dysfunction is implicated in aging, obesity, diabetes, and many chronic diseases. This study provides the first evidence from a randomized trial that boosting the GH/IGF-I axis with a GHRH peptide analog can improve mitochondrial function in humans. Since tesamorelin is FDA-approved (for HIV lipodystrophy), this finding suggests a potential new application for an existing peptide drug and strengthens the scientific case for growth hormone-releasing peptides in metabolic health.
The Bigger Picture
The connection between growth hormone signaling and mitochondrial function is an emerging area in endocrinology and aging research. This study provides clinical evidence supporting what animal studies have suggested — that GH/IGF-I signaling supports mitochondrial health. As interest grows in peptide-based approaches to aging and metabolic dysfunction (including GHRH analogs, GH secretagogues, and GLP-1 agonists), understanding how these peptides affect fundamental cellular energy production adds an important mechanistic dimension.
What This Study Doesn't Tell Us
Relatively small sample size (39 participants) limits statistical power for subgroup analyses. The correlation between IGF-I and PCr recovery, while strong, doesn't prove causation — other effects of tesamorelin could contribute. Only phosphocreatine recovery was used as a mitochondrial marker; direct mitochondrial assessments (biopsy, respiration) were not performed. The study population (obese with reduced GH) is specific and results may not generalize to GH-sufficient individuals. The clinical significance of the observed mitochondrial improvements for patient outcomes is unknown.
Questions This Raises
- ?Would the mitochondrial benefits of tesamorelin translate to improved exercise capacity or metabolic health outcomes?
- ?Is the mitochondrial improvement a direct effect of IGF-I on muscle mitochondria or mediated through other pathways?
- ?Could tesamorelin-induced mitochondrial improvements benefit other conditions associated with mitochondrial dysfunction, like aging or neurodegenerative disease?
Trust & Context
- Key Stat:
- R=0.71 correlation between IGF-I and mitochondrial function Strong positive relationship between tesamorelin-induced IGF-I increases and phosphocreatine recovery improvement over 12 months
- Evidence Grade:
- This is a double-blind, randomized, placebo-controlled trial — the gold standard study design. However, the small sample (n=39) and the correlational nature of the primary finding (IGF-I vs. PCr recovery) rather than a direct treatment effect comparison limit the evidence strength. The 12-month duration is a notable strength.
- Study Age:
- Published in 2014, this study remains relevant as interest in GHRH analogs and growth hormone secretagogues continues to grow. The mitochondrial function findings have been cited in subsequent research on GH/IGF-I and cellular energetics.
- Original Title:
- The effects of tesamorelin on phosphocreatine recovery in obese subjects with reduced GH.
- Published In:
- The Journal of clinical endocrinology and metabolism, 99(1), 338-43 (2014)
- Authors:
- Makimura, Hideo(2), Murphy, Caitlin A, Feldpausch, Meghan N(2), Grinspoon, Steven K
- Database ID:
- RPEP-02435
Evidence Hierarchy
Frequently Asked Questions
What is tesamorelin and how does it work?
Tesamorelin is a synthetic version of growth hormone-releasing hormone (GHRH), a peptide naturally produced in the brain that tells the pituitary gland to release growth hormone. By mimicking this natural signal, tesamorelin stimulates the body's own GH production, which in turn raises IGF-I levels. It's FDA-approved for reducing excess abdominal fat in people with HIV lipodystrophy and is given as a daily injection.
What is phosphocreatine recovery and why does it measure mitochondrial function?
After muscles use energy during exercise, they need to recharge their energy stores (phosphocreatine). This recharging is entirely dependent on mitochondria — the cell's power plants. By using special MRI (31P spectroscopy) to measure how quickly phosphocreatine recovers after exercise, researchers can directly assess how well mitochondria are working. Faster recovery means better mitochondrial function.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-02435APA
Makimura, Hideo; Murphy, Caitlin A; Feldpausch, Meghan N; Grinspoon, Steven K. (2014). The effects of tesamorelin on phosphocreatine recovery in obese subjects with reduced GH.. The Journal of clinical endocrinology and metabolism, 99(1), 338-43. https://doi.org/10.1210/jc.2013-3436
MLA
Makimura, Hideo, et al. "The effects of tesamorelin on phosphocreatine recovery in obese subjects with reduced GH.." The Journal of clinical endocrinology and metabolism, 2014. https://doi.org/10.1210/jc.2013-3436
RethinkPeptides
RethinkPeptides Research Database. "The effects of tesamorelin on phosphocreatine recovery in ob..." RPEP-02435. Retrieved from https://rethinkpeptides.com/research/makimura-2014-the-effects-of-tesamorelin
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Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.