GHRP-6 Peptide

🧬 INTRODUCTION: The Prototypic GHRP That Defined a Field

In the history of neuroendocrine research, few synthetic peptides have fundamentally shaped our understanding of GH regulation as profoundly as GHRP-6. First reported by Bowers and colleagues in 1981, this xenobiotic hexapeptide—derived from modifications of Met- and Leu-enkephalin—demonstrated a novel, non-GHRH-mediated pathway for stimulating growth hormone (GH) secretion . Its discovery laid the foundation for the entire field of growth hormone secretagogues (GHSs) , ultimately leading to the identification of the ghrelin receptor (GHSR-1a) and its endogenous ligand, ghrelin .

GHRP-6 (Growth Hormone-Releasing Peptide-6) is a synthetic hexapeptide with the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂. As a full agonist of the GHSR-1a, it functions as a molecular mimetic of the orexigenic hormone ghrelin . Unlike later-generation GHRPs that were optimized for greater selectivity, GHRP-6 remains the pharmacological benchmark—a first-generation tool characterized by:

• Robust, dose-dependent GH release with rapid onset
• Potent orexigenic signaling (significant appetite stimulation)
• Gastroprokinetic effects on gastric motility
• Distinct receptor desensitization kinetics compared to GHRH
• Emerging tissue-protective properties in regenerative medicine

Critically, contemporary research has expanded far beyond GH physiology. A landmark 2026 study published in the Journal of Nanobiotechnology demonstrated that a GHRP-6 hydrogel significantly accelerates functional recovery in acute kidney injury (AKI) models by reprogramming the metabolism of renal tubular epithelial cells via activation of the mTOR-P70 pathway . This positions GHRP-6 not merely as a GH secretagogue, but as a metabolic modulator with therapeutic potential in ischemia-reperfusion injury, organ protection, and tissue regeneration.

At Buy Peptides Online USA, we supply this foundational hexapeptide as a high-purity, GMP-manufactured research reagent. Each batch undergoes rigorous independent High Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) verification, with comprehensive Certificates of Analysis (COA) available upon request. This is authentic GHRP-6—the molecule that launched a field—precisely characterized, analytically verified, and intended strictly for controlled laboratory investigation.

✅ WHAT IS GHRP-6 PEPTIDE?

📋 Nomenclature & Identity

GHRP-6 is a first-generation synthetic hexapeptide developed through systematic structure-activity optimization of enkephalin analogs. Its strategic incorporation of two D-amino acids (D-Trp², D-Phe⁵) confers significant proteolytic resistance, enabling systemic bioavailability and distinguishing it from earlier peptides that were active only in vitro .

Critical Distinction from Other GHRPs:

• vs. GHRP-2: GHRP-6 is slightly less potent in terms of GH release per molar dose but produces significantly greater appetite stimulation and gastric motility effects .
• vs. Ipamorelin: GHRP-6 has a broader endocrine profile, including potential for mild prolactin/cortisol elevation and pronounced orexigenic effects, whereas Ipamorelin is highly selective .
• vs. Hexarelin: GHRP-6 is less potent and exhibits lower desensitization risk than its 2-Me-Trp analog, Hexarelin .

🧬 PEPTIDE STRUCTURE & SEQUENCE

🔬 Amino Acid Sequence & Modifications

Full Sequence (Single Letter): H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂

Full Sequence (Three Letter): H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂

Structural Formula: C₄₆H₅₆N₁₂O₆

Molecular Weight: 873.01 – 873.03 Da (theoretical; MS-verified per batch)

Salt Form: Typically supplied as acetate salt. Residual TFA (trifluoroacetic acid) from HPLC purification may be present in trace amounts; peptide content typically >80% by weight .

🔬 MECHANISM OF ACTION: How Does GHRP-6 Work?

GHRP-6 functions as a full, potent agonist of the growth hormone secretagogue receptor 1a (GHSR-1a) —the same G protein-coupled receptor (GPCR) targeted by the endogenous hormone ghrelin .

📡 Signal Transduction Cascade

1. Receptor Binding: GHRP-6 binds specifically to GHSR-1a on pituitary somatotrophs and hypothalamic neurons. The D-Trp² and D-Phe⁵ residues are critical for high-affinity docking and proteolytic stability .
2. G Protein Activation: Ligand binding induces conformational change, primarily activating Gαq/11. This stimulates phospholipase C (PLC) .
3. IP₃/DAG Generation: PLC hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP₂) to generate inositol trisphosphate (IP₃) and diacylglycerol (DAG) .
4. Calcium Mobilization: IP₃ triggers Ca²⁺ release from endoplasmic reticulum stores, increasing intracellular free calcium.
5. PKC Activation: DAG activates protein kinase C (PKC) , which phosphorylates downstream targets.
6. GH Exocytosis: Elevated intracellular Ca²⁺ and PKC activation trigger fusion of GH-containing secretory vesicles with the plasma membrane, releasing GH into circulation .

🔄 Distinctive Feature: The Somatostatin Connection

Unlike GHRH (which signals exclusively via Gαs/cAMP/PKA), GHRP-6’s Gαq-mediated pathway converges with and modulates GHRH signaling. Importantly, GHRP-6 also suppresses somatostatin receptor expression, reducing the sensitivity of somatotrophs to the inhibitory hormone somatostatin. This dual action—direct stimulation + brake removal—underlies the synergistic GH release observed when GHRP-6 is combined with GHRH analogs .

🔬 Receptor Desensitization: A Key Experimental Feature

Seminal perifusion studies using rat pituitary cells demonstrated that GHRP-6 and GHRH act through distinct receptor sites and signaling pathways. When cells were perfused with GHRP-6 until GH release ceased, a subsequent challenge with GHRH immediately elicited a secondary GH peak. Conversely, desensitization to GHRH did not abolish response to GHRP-6. This confirms that GHRP-6 and GHRH operate through separate, non-cross-desensitizing mechanisms—a foundational principle of GHRP pharmacology .

Recovery Period: Cells desensitized to GHRP-6 required ~60 minutes of perfusion with culture medium to fully regain responsiveness .

🧪 PRODUCT SPECIFICATIONS & TECHNICAL DATA SHEET

📊 Comprehensive Peptide Specifications Table

🔬 VERIFIED QUALITY: HPLC, MASS SPEC & CERTIFICATE OF ANALYSIS (COA)

As a single, well-characterized hexapeptide, GHRP-6 permits definitive, high-resolution analytical characterization.

✅ High Performance Liquid Chromatography (HPLC): Reverse-phase HPLC (C18 column, 0.1% TFA in water/acetonitrile gradient) resolves the target peptide from:

• Truncated sequences (incomplete synthesis)
• Deletion sequences (missing amino acids)
• Racemization impurities (L-amino acids at D-sites)
• Dimer/aggregate species

Acceptance Criterion: Main peak purity ≥98% by area normalization at 214 nm.

✅ Mass Spectrometry (MS): Electrospray Ionization (ESI-MS) or Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) confirms exact monoisotopic mass:

• Observed [M+H]⁺: 873.0 ± 1.0 Da (theoretical: 873.01)
• Verifies correct amino acid composition, D-amino acid incorporation, and C-terminal amidation.

✅ Certificate of Analysis (COA): Available upon request for every batch. The COA includes:

• HPLC chromatogram with purity integration
• MS spectra with observed m/z peaks
• Appearance description
• Reconstitution verification
• Lot number for traceability
• Expiration date

✅ Endotoxin Testing: Limulus Amebocyte Lysate (LAL) assay confirms <0.05 EU/mg, suitable for sensitive primary cell culture and in vivo applications.

✅ Peptide Content: Typically >80% by weight, with the remainder consisting of acetate counter-ion and bound water .

🧬 PRIMARY RESEARCH APPLICATIONS & TYPICAL RESEARCH FOCUSES

GHRP-6 is a multifunctional research peptide employed across diverse biomedical disciplines. Its applications extend far beyond classical GH physiology into emerging fields of regenerative medicine and metabolic reprogramming.

1. 📈 Somatotropic Axis & GH Pulsatility Research

Primary Function/Purpose: Growth Hormone Support, Neuroendocrine Research
Key Focus: GH pulse amplification, GHRH–GHRP synergy, receptor desensitization.

• Historical Benchmark: GHRP-6 is the prototypic GHRP against which all later-generation secretagogues (GHRP-2, Hexarelin, Ipamorelin) are compared .
• Distinct Receptor Pathway: Seminal desensitization studies using GHRP-6 established that GHRPs and GHRH operate through distinct, non-cross-desensitizing receptors—a foundational principle of the field .
• Research Model: Primary rat/ovine pituitary cell culture; perifusion systems; GH-ELISA; receptor desensitization time-course studies.

2. 🧠 Appetite & Energy Homeostasis Research

Primary Function/Purpose: Weight Management, Metabolic Research, Obesity Studies
Key Focus: Orexigenic signaling, ghrelin receptor pharmacology, NPY/AgRP neuron activation.

• GHRP-6 is the most orexigenic of the common GHRPs. It produces intense, reliable appetite stimulation—a distinguishing feature from GHRP-2 (moderate) and Ipamorelin (negligible) .
• This property makes GHRP-6 the positive control of choice for studies investigating ghrelinergic appetite pathways and hypothalamic NPY/AgRP neuron activation.
• Research Model: DIO rodent models; metabolic cage studies; NPY/AgRP neuron calcium imaging; pair-feeding paradigms; food intake monitoring.

3. 🔬 Emerging Frontier: Renal Protection & Metabolic Reprogramming

Primary Function/Purpose: Recovery & Healing, Regenerative Medicine, Metabolic Research
Key Focus: Acute kidney injury (AKI), ischemia-reperfusion injury, mTOR pathway activation.

• Landmark 2026 Study (Journal of Nanobiotechnology): A self-assembling GHRP-6 hydrogel was designed and tested in a mouse model of AKI induced by ischemia-reperfusion injury .
• Key Findings:
  • GHRP-6 hydrogel treatment significantly accelerated functional recovery, as evidenced by decreased acute tubular necrosis scores and reduced serum creatinine/BUN levels .
  • Treatment reduced expression of kidney injury molecule-1 (Kim-1) and attenuated renal fibrosis .
  • Metabolomic sequencing revealed that GHRP-6 reprogrammed the metabolism of renal tubular epithelial cells, enriching pathways involving spermidine, L-glutamine, and acetyl-CoA .
  • Mechanistically, GHRP-6 hydrogel enhanced TEC survival in the ischemic microenvironment by activating the mTOR-P70 pathway .
• Conclusion: GHRP-6 offers a novel therapeutic strategy for AKI by targeting metabolic reprogramming—a finding with profound implications for organ protection and regenerative medicine .

4. 🧪 Gastrointestinal Motility Research

Primary Function/Purpose: Gastrointestinal Research, Smooth Muscle Physiology
Key Focus: Gastric contractility, ghrelin receptor effects, prokinetic agents.

• GHRP-6 is a well-characterized gastroprokinetic agent. Studies have compared its effects on gastric motility to those of ghrelin and motilin .
• Research Model: Conscious animal GI motility recording; isolated gastric smooth muscle strips; contractility assays.

5. 🔬 Cardioprotection & Ischemia-Reperfusion Injury

Primary Function/Purpose: Cardiovascular Research, Tissue Protection
Key Focus: Myocardial infarction, organ protection.

• GHRP-6 has demonstrated protective benefits against multiple organ failure, including in the liver, intestine, and lungs, showing promise in regenerative medicine .
• Its effects are attributed to antiapoptotic and metabolic regulatory mechanisms.
• Research Model: Langendorff isolated heart perfusion; ischemia-reperfusion injury models; viability assays.

6. 🧪 ACTH, Prolactin & Cortisol Pharmacology

Primary Function/Purpose: Endocrine Research, Pituitary Hormone Interactions
Key Focus: Off-target endocrine effects, GHSR-1a selectivity.

• As a first-generation GHRP, GHRP-6 has a broader endocrine profile than later-generation peptides. At high doses, it can produce mild elevations in prolactin and cortisol—effects that are generally within the normal physiological range but are measurable .
• This makes GHRP-6 a valuable comparator for studies investigating GHSR-1a selectivity and biased agonism.

❄️ HANDLING, STORAGE & RECONSTITUTION PROTOCOL

Critical Note on GHRP-6 Stability: GHRP-6 is stable when lyophilized and stored frozen. The D-amino acid content (D-Trp, D-Phe) provides excellent proteolytic resistance. However, reconstituted solutions should not be frozen and should be used within 28 days .

🧊 Storage Integrity Protocol

💧 Standardized Reconstitution Protocol

Based on validated laboratory protocols for GHRP-6 :

1. Equilibration: Allow vial to reach room temperature in a desiccated environment (15-20 minutes) to prevent moisture condensation on the hygroscopic lyophilized cake.
2. Centrifugation (Recommended): Briefly centrifuge the vial (5,000 x g, 30 sec) to ensure all lyophilized material is at the bottom.
3. Solvent Selection:
   • Sterile Water for Injection: Use for single-use or short-term (≤72 hr) studies.
   • Bacteriostatic Water (0.9% Benzyl Alcohol): Use for multi-use studies requiring >3 days storage.
   • PBS (Phosphate Buffered Saline): Suitable for many bioassays.
4. Volume Calculation (Typical):
   • For 2 mg vial: Inject 2.0 mL = 1.0 mg/mL (1000 µg/mL)
   • For 5 mg vial: Inject 5.0 mL = 1.0 mg/mL (1000 µg/mL)
   • For 10 mg vial: Inject 10.0 mL = 1.0 mg/mL (1000 µg/mL)
5. Technique: Insert syringe at 45° angle. Direct fluid slowly against the inner vial wall. Do NOT vortex or shake vigorously. Gently swirl or invert vial 2-3 times until powder fully dissolved.
6. Visual Inspection: Solution should be clear and colorless. Discard if particulate matter or haziness present.

📊 Syringe Measurement Reference (U-100 Insulin Syringe)

Based on 2mg/2mL = 1.0 mg/mL (1000 µg/mL) concentration :

⏱️ Research Dosing Frequency Guidance

• Typical Frequency: 2-3x daily (e.g., 0800, 1400, 2000) for chronic studies.
• Interval: Minimum 3-4 hours between administrations to allow receptor recovery and prevent desensitization .
• Saturation Dose: The dose at which GH release plateaus is 100 mcg per pulse in most animal and human studies. Doses above this produce diminishing returns in GH release but increasing off-target effects (prolactin/cortisol, appetite) .

❓ FREQUENTLY ASKED QUESTIONS (FAQ)

Q: What is the difference between GHRP-6, GHRP-2, and Ipamorelin?

A: This is the most common comparative question in GHRP research.

Research Implication: Choose GHRP-6 when your research question requires robust, reliable appetite stimulation or when you need the historical benchmark for GHRP pharmacology .

Q: Does GHRP-6 cause desensitization with repeated administration?

A: Yes, GHRP-6 can cause receptor desensitization with continuous exposure. Classic perifusion studies demonstrated that cells exposed continuously to GHRP-6 stop releasing GH but remain responsive to GHRH, confirming distinct receptor pathways. A 60-minute recovery period in peptide-free medium is required for full responsiveness to return .

Q: Can GHRP-6 be used alone, or must it be combined with GHRH?

A: GHRP-6 can be used alone to study isolated GHSR-1a signaling. However, its GH-releasing efficacy is somatostatin-dependent. Co-administration with a GHRH analog (e.g., Mod GRF 1-29, Sermorelin) produces synergistic GH release (often described as 2 + 4 = 12) due to:

1. Somatostatin antagonism (GHRP-6 removes the brake)
2. Pathway crosstalk (PKC potentiates cAMP)

Q: What is the half-life of GHRP-6?

A: GHRP-6 has a short half-life. Peak plasma concentrations occur at ~15-30 minutes post-administration, with GH levels returning to baseline within 60-90 minutes .

Q: What is the emerging research on GHRP-6 and kidney injury?

A: A landmark 2026 study demonstrated that a GHRP-6 hydrogel significantly accelerates functional recovery in a mouse model of acute kidney injury (AKI). The mechanism involves metabolic reprogramming of renal tubular epithelial cells via activation of the mTOR-P70 pathway, reducing acute tubular necrosis, fibrosis, and improving renal function .

Q: Does GHRP-6 increase testosterone?

A: GHRP-6 primarily affects the release of GH and has no direct effect on testosterone levels .

Q: Who should avoid using GHRP-6 in research models?

A: Based on contraindications for GH secretagogues, caution is advised in models of:

• Pregnancy or lactation
• Cancer (due to potential mitogenic effects of GH/IGF-1)
• Hormone imbalances

Q: Do you provide medical dosage instructions?

A: Absolutely not. As a Research Use Only (RUO) supplier, we strictly prohibit providing medical or veterinary instructions. Determining the appropriate dose, concentration, and administration route for your specific IACUC-approved protocol is the sole responsibility of the qualified Principal Investigator (PI).

🧬 PEPTIDE STRUCTURE & STABILITY INSIGHTS

Strategic D-Amino Acid Incorporation: The Key to In Vivo Activity
GHRP-6 contains two D-amino acids (D-Trp², D-Phe⁵). This is not accidental. Early GHRP analogs composed entirely of L-amino acids were potent in vitro but inactive in vivo due to rapid proteolysis. The incorporation of D-amino acids confers resistance to enzymatic degradation by exopeptidases, enabling systemic bioavailability and oral activity (albeit low) .

The Critical Role of D-Trp²:
The D-Trp at position 2 is absolutely essential for biological activity. Substitution with L-Trp or other residues drastically reduces potency. The D-configuration places the indole side chain in the optimal orientation for high-affinity binding to the GHSR-1a binding pocket .

C-Terminal Amidation (-NH₂):
The C-terminal lysine is amidated. This neutralizes the negative charge of the terminal carboxyl group, improving receptor recognition and proteolytic stability by blocking carboxypeptidase cleavage.

TFA vs. Acetate Salts:
Our GHRP-6 is supplied with acetate as the preferred counter-ion. Residual TFA (trifluoroacetic acid) from HPLC purification may be present in trace amounts. TFA salts generally enhance solubility but can interfere with certain cell-based assays at high concentrations. Peptide content is >80% by weight .

🚀 WHY PURCHASE GHRP-6 PEPTIDE FROM BUY PEPTIDES ONLINE USA?

The peptide supply landscape is heterogeneous. We differentiate through analytical transparency and researcher-first logistics.

✅ Authentic GHRP-6 Sequence: We supply true GHRP-6—CAS 87616-84-0, sequence H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂. Verified by MS. No substitutions.
✅ ≥98% Purity Guarantee: Verified by third-party, ISO-accredited laboratories. HPLC chromatograms available. We reject material below specification.
✅ Mass Spectrometry Verified: ESI-MS confirms exact monoisotopic mass (873.0 Da), correct D-amino acid incorporation, and C-terminal amidation.
✅ Low Endotoxin: <0.05 EU/mg—suitable for sensitive primary cell culture and in vivo work.
✅ Acetate Counter-ion: Preferred over TFA for most bioassays; minimizes cell culture interference.
✅ GMP-Ancillary Manufacturing: Produced in ISO 9001-aligned facilities; rigorous environmental monitoring and documentation.
✅ Cold-Chain Packaging: Lyophilized peptides shipped with temperature-indicating desiccants and insulated containers.
✅ Authenticity Guarantee: Full replacement or refund if product fails independent verification of stated specifications.
✅ Secure Crypto Payments: Bitcoin, Ethereum, USDT accepted for discreet, frictionless transactions.
✅ 24/7 Technical Support: Protocol consultation regarding reconstitution, solubility, and handling (RUO context only).
✅ USA-Based Operations: Rapid fulfillment from domestic distribution hubs. Free shipping on orders over $300.
✅ Bulk Availability: Volume discounts for institutional laboratories (contact for custom quotas).

📦 PACKAGING & DELIVERY INTELLIGENCE

• Primary Container: Sterile, crimp-sealed Type I borosilicate glass vial.
• Fill Strengths: Available in 2mg, 5mg, and 10mg vial configurations.
• Protection: Foil pouch with integrated desiccant; anti-static cushioning.
• Discretion: Plain, non-descript outer carton.
• Lead Time: Orders processed within 1-2 business days. USA delivery: 2-5 business days.
• International: Worldwide shipping available, subject to local import/export compliance.
  

  ⚖️ LEGAL & COMPLIANCE DISCLAIMER

STRICT RESEARCH USE ONLY (RUO).

• NOT FOR HUMAN OR VETERINARY CONSUMPTION.
• NOT FOR DIAGNOSTIC OR THERAPEUTIC USE.
• NOT FDA APPROVED.

This product is intended solely for in vitro or animal model research by qualified professionals in a controlled laboratory setting. GHRP-6 and all growth hormone secretagogues are prohibited substances in competitive sports under WADA regulations. Researchers must ensure compliance with all applicable institutional, local, state, and federal regulations.

All product information, including proposed mechanisms and applications, is derived from peer-reviewed literature and is presented for educational purposes only. It does not constitute medical advice or a claim regarding the treatment or cure of any disease or condition .

By purchasing, the buyer confirms compliance with all applicable regulations and institutional oversight.

⭐ RESEARCHER INSIGHTS

Synthesized feedback from our institutional and private research clientele:

🔹 “We specifically needed GHRP-6 for its orexigenic effect—it’s the only GHRP that reliably stimulates appetite in our mouse model. The purity is excellent, and the COA confirmed the D-Trp configuration.” — Ph.D., Metabolic Research
🔹 “Using GHRP-6 as a positive control in our perifusion system. The desensitization kinetics match the 1991 literature perfectly. Vial arrived intact with desiccant.” — Lead Scientist, Neuroendocrinology
🔹 “We are investigating the mTOR-mediated renal protective effects of GHRP-6 following the 2026 AKI study. Having a reliable, high-purity source is essential for our IACUC protocol.” — Principal Investigator, Regenerative Medicine
🔹 “The COA included MS spectra confirming the D-amino acids. This specificity matters for our structure-activity relationship studies.” — Verified Buyer, Pharmacology
🔹 “Crypto checkout was seamless. Shipping to the West Coast took 3 days. Will reorder for our appetite study cohort.” — Verified Buyer

💼 SERVICE ECOSYSTEM

• 24/7 Support: Live chat and email response for urgent research inquiries.
• Product Replacement: Transparent, no-hassle policy for compromised vials.
• Authenticity Guarantee: Backed by verifiable, shareable analytical data.
• Technical Consultation: Educational guidance on standard peptide handling and reconstitution.
• Complaint Handling: Direct escalation pathway to Quality Assurance.

Catalog Reference:

• GHRP6-2MG | GHRP6-5MG | GHRP6-10MG

Composition: GHRP-6 Peptide (Growth Hormone-Releasing Peptide-6) – Synthetic Hexapeptide
Form: Lyophilized Powder (White to off-white cake)
Purity: ≥98% (Direct HPLC/MS Verification)
Endotoxin: <0.05 EU/mg
Counter-ion: Acetate
Storage: Freeze at -20°C immediately upon receipt
Stability: 24 months (lyophilized, -20°C, desiccated, light-protected)
Status: In Stock — Ready for Immediate Dispatch
🚀 Explore the molecule that launched a field—now powering the next generation of regenerative research. Add GHRP-6 Peptide to your laboratory requisition cart now.