What is Hexarelin?
Hexarelin is a synthetic hexapeptide growth hormone secretagogue and GHS-R1a agonist studied in retinal, renal and metabolic research models. This page summarises the published preclinical evidence.
Hexarelin is a synthetic hexapeptide growth hormone secretagogue, also referred to in the literature as a growth hormone-releasing peptide, and it is classified as a growth hormone secretagogue receptor type 1a (GHS-R1a) agonist [1]. It is grouped in the pharmacological literature alongside other growth hormone secretagogues such as GHRP-2, GHRP-6 and ipamorelin, and alongside GHRH analogues, as one of the peptides marketed as "research compounds" intended to modulate the growth hormone–insulin-like growth factor-1 (GH-IGF-1) axis [3]. The evidence block supplied for this page does not give a residue sequence, molecular formula or molecular weight for hexarelin, so none are stated here.
The work summarised below centres on the growth hormone secretagogue receptor type 1a, the receptor through which hexarelin is described as acting [1], and which is also the receptor bound by the related secretagogue alexamorelin [7].
Research Studies
Hexarelin and retinal ganglion cell survival after optic nerve transection
Hexarelin was studied for neuroprotective effect on the survival of retinal ganglion cells (RGCs) in the retina following optic nerve transection (ONT) [1]. The work used golden hamsters aged 8–9 weeks. In a one-dose-per-day design, animals received saline or hexarelin at 25 μg/kg, 50 μg/kg or 100 μg/kg daily for 5 days following ONT. In a two-dose-per-day design, animals received saline, 100 μg/kg or 150 μg/kg hexarelin twice daily for 5 days. Survival of RGCs was quantified by immunostaining with Tuj1 [1]. The paper describes hexarelin as a GHS-R1a agonist with a potent anti-apoptotic effect [1].
| Parameter | Detail as reported [1] |
|---|---|
| Model | Optic nerve transection, golden hamsters 8–9 weeks old |
| Dosing arms (once daily) | Saline; 25 μg/kg; 50 μg/kg; 100 μg/kg, for 5 days |
| Dosing arms (twice daily) | Saline; 100 μg/kg; 150 μg/kg, for 5 days |
| Outcome measure | RGC survival by Tuj1 immunostaining |
Hexarelin and apoptosis in ischemic acute kidney injury
Hexarelin has been reported to protect against organ injury in models of ischemia/reperfusion (I/R)-induced injury, and one study examined its effect on acute kidney injury (AKI) and the mechanism involved [2]. In an I/R-induced AKI model, rats were pretreated with hexarelin at 100 μg/kg/d for 7 days and sacrificed 24 h post-IRI; kidney function, histology and apoptosis were then assessed. The study combined in vivo and in vitro experiments and reports that hexarelin alleviates apoptosis in this setting via the MDM2/p53 pathway [2].
| Parameter | Detail as reported [2] |
|---|---|
| Model | I/R-induced AKI, rat; plus in vitro experiments |
| Pretreatment | 100 μg/kg/d for 7 days |
| Timepoint | Sacrifice 24 h post-IRI |
| Assessed | Kidney function, histology, apoptosis |
| Reported pathway | MDM2/p53 |
Hexarelin and the GH-IGF-1 axis in the performance-enhancing peptide literature
A review of performance-enhancing peptides that modulate the GH-IGF-1 axis lists hexarelin among the growth hormone secretagogues most commonly encountered in clinical practice and in online self-administration protocols, together with GHRP-2, GHRP-6 and ipamorelin [3]. The same review frames these agents as unregulated peptides marketed as "research compounds" [3]. This is a characterisation of the market and clinical landscape rather than a report of an experimental effect of hexarelin in a model.
Hexarelin and CD36 modulation in a SARS-CoV-2 mouse model
A study of the hyper-inflammatory response to SARS-CoV-2 infection used a cluster of differentiation 36 (CD36) receptor modulator in K18-hACE2 mice [4]. The paper notes that viral infection stimulates alveolar macrophages to adopt an inflammatory phenotype regulated, at least in part, by mechanisms the modulator was used to target [4]. The evidence block does not state that hexarelin itself was the modulator tested, and no hexarelin-specific finding from this paper is reported here.
Hexarelin and permeation enhancers in the presence of intestinal bile salts
All-atom molecular dynamics simulations were used to investigate the interaction between two permeability enhancers (sodium caprate and SNAC) and four peptides — octreotide, hexarelin, degarelix and insulin — in the presence of taurocholate, an intestinal bile salt [5]. The enhancers showed distinct effects on peptide release depending on their properties, promoting release of hydrophobic peptides while inhibiting release of water-soluble peptides. Lowering peptide concentrations in the simulations reduced peptide–peptide interactions but increased their interactions with other components of the system [5]. This is a computational, in vitro-style study of formulation behaviour, not an in vivo finding.
Hexarelin and MPTP-induced lung injury in mice
A study in mice investigated the protective and therapeutic effects of hexarelin against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced lung injury, evaluating oxidative stress, IL-6-mediated inflammation and Caspase-3-dependent apoptosis [6]. The work used fifty male Balb/C mice [6]. This is an animal model of chemically induced lung injury.
Hexarelin and hepatocyte incubation in secretagogue biomarker work
Work on alexamorelin, a synthetic peptide and growth hormone secretagogue with potential performance-enhancing properties, used human hepatocyte incubations and high-resolution mass spectrometry to identify consumption biomarkers [7]. Alexamorelin is described as mimicking the natural peptide hormone ghrelin by binding to the GHS type 1a receptor (GHS-R1a) [7]. This paper concerns alexamorelin rather than hexarelin, and is cited here only for the shared receptor context.
Where the evidence sits
Across the studies above, the hexarelin-specific findings come from animal models — hamsters after optic nerve transection [1], rats after renal ischemia/reperfusion [2], and mice after MPTP-induced lung injury [6] — and from computational simulation of peptide behaviour with permeation enhancers [5]. The GH-IGF-1 axis review [3] and the alexamorelin biomarker paper [7] are contextual rather than experimental reports of hexarelin activity. No human outcome data for hexarelin is supplied in the evidence block for this page, and none is claimed here.
If you are reading this for personal health reasons
This material is sold for laboratory research only, and we do not provide dosing or medical guidance. Nothing on this page is a recommendation for human use. Anyone considering a compound for themselves should speak to a licensed clinician.
Sources
- [1] Hexarelin promotes the survival of retinal ganglion cells after optic nerve transection. https://europepmc.org/article/PMC/PMC13004568
- [2] Hexarelin alleviates apoptosis on ischemic acute kidney injury via MDM2/p53 pathway. https://europepmc.org/article/PMC/PMC10500723
- [3] The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. https://europepmc.org/article/PMC/PMC13322892
- [4] Pharmacological targeting of the hyper-inflammatory response to SARS-CoV-2-infected K18-hACE2 mice using a cluster of differentiation 36 receptor modulator. https://europepmc.org/article/PMC/PMC10879382
- [5] Revealing the interaction between peptide drugs and permeation enhancers in the presence of intestinal bile salts. https://pubmed.ncbi.nlm.nih.gov/37982184/
- [6] Protective and restorative effects of hexarelin on MPTP-induced lung injury in mice. https://pubmed.ncbi.nlm.nih.gov/42619489/
- [7] Identification of alexamorelin consumption biomarkers using human hepatocyte incubations and high-resolution mass spectrometry. https://pubmed.ncbi.nlm.nih.gov/40465419/