Research Applications
Growth Hormone Release and Metabolic Function
Ipamorelin demonstrates potent growth hormone releasing properties with remarkable selectivity. Research published in the European Journal of Endocrinology shows that ipamorelin released growth hormone from primary rat pituitary cells with potency and efficacy similar to GHRP-6, with EC50 values of 1.3±0.4 nmol/L and maximum efficacy of 85±5%. In conscious swine, ipamorelin released growth hormone with an ED50 of 2.3±0.03 nmol/kg and maximum efficacy of 65±0.2 ng GH/mL plasma, demonstrating effectiveness across species.
The peptide's selectivity is particularly notable when compared to other growth hormone secretagogues. Studies show that while GHRP-2 and GHRP-6 administration resulted in increased plasma levels of ACTH and cortisol, ipamorelin did not release ACTH or cortisol at levels significantly different from those observed following growth hormone-releasing hormone (GHRH) stimulation. This lack of effect on stress hormones was evident even at doses more than 200-fold higher than the ED50 for growth hormone release, establishing ipamorelin as the first GHRP-receptor agonist with selectivity for growth hormone release similar to GHRH itself.
Animal studies demonstrate that ipamorelin increases insulin secretion through both calcium channel and adrenergic receptor pathways. Research examining pancreatic tissue fragments from normal and diabetic rats found that ipamorelin evoked significant increases in insulin secretion at concentrations ranging from 10^-12 to 10^-6 M. This dual-action mechanism—stimulating both growth hormone and insulin release—contributes to improved metabolic function and glucose homeostasis.
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Muscle Growth and Preservation
Ipamorelin demonstrates significant effects on muscle mass and strength through its growth hormone stimulatory properties. Research shows that the peptide promotes muscle growth through multiple mechanisms including enhanced protein synthesis, increased satellite cell activation, and improved muscle fiber regeneration mediated through IGF-1 pathways. Animal studies indicate that growth hormone increases from ipamorelin treatment can produce increases of approximately 9% in muscle mass without changes to dietary intake or exercise volume.
The peptide exhibits powerful muscle-protective properties, particularly in preventing glucocorticoid-induced muscle wasting. Research published in Growth Hormone & IGF Research demonstrates that the growth hormone secretagogue ipamorelin counteracts the catabolic effects of glucocorticoids on skeletal muscles. In studies with adult female rats injected with methylprednisolone (a glucocorticoid), simultaneous administration of ipamorelin 100 μg/kg three times daily for 3 months significantly increased maximum tetanic tension of calf muscles compared to the glucocorticoid-only group. The peptide effectively reversed the muscle strength decrease caused by glucocorticoid treatment.
Studies further demonstrate that ipamorelin suppresses myostatin expression, a negative regulator of muscle mass, and inhibits muscle atrophy signaling pathways. This mechanism helps preserve lean muscle mass during metabolic stress or caloric restriction conditions where muscle catabolism typically occurs. The peptide's ability to maintain skeletal muscle homeostasis by regulating genes involved in proteostasis, heat shock response, and metabolic adaptation makes it valuable for preventing sarcopenia and age-related muscle decline.
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- Andersen NB, et al. "The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats." Growth Hormone & IGF Research. 2001;11(5):266-72. https://pubmed.ncbi.nlm.nih.gov/11735244/
- Johansen PB, et al. "Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats." Growth Hormone & IGF Research. 1999;9(2):106-13. https://pubmed.ncbi.nlm.nih.gov/10373343/
Fat Loss and Body Composition
Ipamorelin demonstrates significant effects on fat metabolism and body composition through its growth hormone stimulatory actions. Research indicates that growth hormone promotes lipolysis in adipose tissue, particularly in visceral and subcutaneous depots, through activation of hormone-sensitive lipase (HSL) and modulation of lipid droplet protein expression. Animal studies show that increased growth hormone levels from ipamorelin treatment can produce decreases of approximately 14% in fat mass without dietary modifications.
Unlike other ghrelin mimetics such as GHRP-6 that strongly stimulate appetite, ipamorelin demonstrates a unique property of not significantly increasing hunger despite its ghrelin receptor activation. This characteristic makes it particularly valuable for body composition optimization during fat-loss phases. Studies in growth hormone-deficient mice show that while other growth hormone secretagogues increased body fat through growth hormone-independent mechanisms that included increased feeding, ipamorelin's effects on body composition are primarily mediated through its growth hormone-releasing properties.
The peptide enhances metabolic flexibility—the capacity to switch between carbohydrate and fat oxidation—which is crucial for optimal body composition. Research demonstrates that ipamorelin treatment increases fatty acid oxidation and β-oxidation in skeletal muscle, promoting the utilization of stored fat as an energy source. The peptide also improves insulin sensitivity, which is strongly associated with favorable body composition and reduced visceral adiposity. These metabolic effects occur through the growth hormone/IGF-1 axis, which plays a central role in regulating lipid metabolism and energy homeostasis.
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Bone Health and Longitudinal Growth
Ipamorelin demonstrates significant effects on bone metabolism and longitudinal growth through its growth hormone stimulatory properties. Research published in Growth Hormone & IGF Research shows that ipamorelin dose-dependently increased longitudinal bone growth rate (LGR) in adult female rats. After 15 days of treatment with ipamorelin at doses of 18, 90, and 450 μg/day (injected subcutaneously three times daily), LGR increased from 42 μm/day in the vehicle group to 44, 50, and 52 μm/day in the treatment groups (P<0.0001). There was also a pronounced and dose-dependent effect on body weight gain.
The peptide demonstrates powerful bone-protective effects against glucocorticoid-induced bone loss. Studies show that glucocorticoids, commonly used to treat inflammatory conditions, cause significant decreases in bone formation that can lead to osteoporosis and increased fracture risk. Research demonstrates that ipamorelin administration completely counteracted glucocorticoid-induced decreases in bone formation. In rats treated with methylprednisolone, simultaneous administration of ipamorelin increased periosteal bone formation rate four-fold compared to the glucocorticoid-only group, effectively reversing the catabolic bone effects.
The mechanism involves IGF-1-mediated stimulation of osteoblast proliferation and enhanced collagen synthesis in bone matrix. Growth hormone and IGF-1 increase bone mineral content and density by promoting osteoblast activity while reducing osteoclast-mediated bone resorption. Animal studies using dual-energy X-ray absorptiometry (DEXA) scans demonstrate that ipamorelin treatment significantly increased bone mineral content in young rats, with effects persisting over 12-week treatment periods. These findings suggest therapeutic potential for conditions characterized by bone loss, including osteoporosis, age-related bone density decline, and glucocorticoid-induced osteoporosis.
Sources:
- Johansen PB, et al. "Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats." Growth Hormone & IGF Research. 1999;9(2):106-13. https://pubmed.ncbi.nlm.nih.gov/10373343/
- Andersen NB, et al. "The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats." Growth Hormone & IGF Research. 2001;11(5):266-72. https://pubmed.ncbi.nlm.nih.gov/11735244/
Recovery and Gastrointestinal Function
Ipamorelin demonstrates significant prokinetic effects on gastrointestinal motility, particularly in accelerating recovery from postoperative ileus (POI), a common complication following abdominal surgery characterized by transient loss of gastrointestinal motility. Research published in the Journal of Experimental Pharmacology shows that ipamorelin significantly accelerates gastric emptying in rodent models of gastroparesis induced by abdominal surgery and intestinal manipulation.
In controlled studies, rats subjected to laparotomy and intestinal manipulation showed delayed gastric emptying with 78%±5% of a meal remaining in the stomach after 15 minutes in vehicle-treated controls. Ipamorelin administration at 0.014 μmol/kg intravenously resulted in significant acceleration of gastric emptying (P<0.05 versus vehicle), with only 52%±11% of the meal remaining in the stomach—levels approaching those of non-surgical control animals (44%±6%). The higher dose of 0.14 μmol/kg had even greater effects, with less than 25% of radioactivity remaining in the stomach after 15 minutes.
The mechanism involves stimulation of gastric contractility through ghrelin receptor-mediated pathways located on cholinergic excitatory neurons. In isolated gastric smooth muscle preparations from rats with POI, ipamorelin normalized contractile responses to both acetylcholine and electrical field stimulation that were markedly inhibited following surgery. These findings suggest ipamorelin improves delayed gastric emptying by directly enhancing gastric motility through neural activation.
Clinical research has explored ipamorelin's potential in human POI management. A prospective, randomized, controlled proof-of-concept study in bowel resection patients investigated ipamorelin 0.03 mg/kg administered twice daily for up to 7 days. While the study found no significant differences in the primary efficacy endpoint (time to first tolerated meal), the ipamorelin group showed reduced median time to first tolerated meal (25.3 hours versus 32.6 hours in placebo) and had fewer overall treatment-emergent adverse events (87.5% versus 94.8%). These preliminary findings suggest potential benefits worthy of further investigation with optimized dosing protocols.
Sources:
- Greenwood-Van Meerveld B, et al. "Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus." Journal of Experimental Pharmacology. 2012;4:149-55. https://pubmed.ncbi.nlm.nih.gov/27186127/
- Beck DE, et al. "Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients." International Journal of Colorectal Disease. 2014;29(12):1527-34. https://pubmed.ncbi.nlm.nih.gov/25331030/
Anti-Aging and Tissue Regeneration
Ipamorelin's growth hormone stimulatory effects provide significant benefits for age-related decline in physiological function. Research indicates that endogenous growth hormone secretion declines substantially with aging, with levels at age 70 approximately 60% lower than at age 20. This decline contributes to multiple hallmarks of aging including decreased muscle mass and strength, increased fat accumulation, reduced bone density, impaired cognitive function, and compromised immune system performance.
Studies demonstrate that ipamorelin-induced increases in growth hormone and IGF-1 levels can help counteract these age-related changes. The peptide supports connective tissue regeneration through enhanced collagen synthesis, which is crucial for maintaining skin elasticity, joint health, and structural integrity of tissues. Growth hormone promotes improved skin health by increasing dermal thickness, collagen content, and hydration—factors that decline with aging and contribute to wrinkle formation and loss of skin elasticity.
The peptide enhances sleep quality, particularly slow-wave (deep) sleep phases when natural growth hormone secretion normally peaks. Improved sleep architecture supports recovery, cognitive function, and overall metabolic health. Research suggests that growth hormone's natural circadian rhythm enhancement through ipamorelin administration may improve sleep-promoting neuronal circuits in the hypothalamus, contributing to more restorative rest patterns.
Ipamorelin also demonstrates neuroprotective properties through growth hormone and IGF-1 actions on neural tissue. These factors support neuronal survival, promote synaptic plasticity, and enhance cognitive function. The peptide's ability to maintain cellular energy metabolism through improved mitochondrial function and insulin sensitivity contributes to overall cellular health and resilience against age-related metabolic dysfunction. Additionally, growth hormone's role in immune system function means that ipamorelin may help maintain immune competence that typically declines with advancing age.
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Disclaimer: The research articles listed above are for informational purposes only.
This product is intended for research use only and not for human or veterinary use.
