HGH is a research compound studied for its role in performance & hormone research. This page covers mechanism of action, published studies, preclinical protocols, and analytical specifications.
Store lyophilized at -20°C. After reconstitution, store at 4°C and use within 14 days. Do NOT freeze reconstituted solution — this degrades the protein.
Reconstitution
Add 1–2ml bacteriostatic water per vial. Inject slowly along vial wall. Swirl gently — vigorous shaking denatures the protein.
Mechanism of Action
Human growth hormone (somatropin) is a 191-amino acid, single-chain polypeptide produced by somatotroph cells in the anterior pituitary gland. Recombinant HGH (rhGH) is biosynthetically identical to the endogenous protein, produced via recombinant DNA technology in E. coli or mammalian cell expression systems.
GH Receptor Activation and JAK2-STAT5 Signalling: HGH binds to the GH receptor (GHR), a transmembrane receptor belonging to the cytokine receptor superfamily. One GH molecule sequentially binds two GHR molecules, inducing receptor dimerisation. This activates the receptor-associated Janus kinase 2 (JAK2), which phosphorylates STAT5 transcription factors. STAT5 dimers translocate to the nucleus, activating GH-responsive gene expression including IGF-1, IGFBP-3, and metabolic enzymes.
IGF-1 Axis: The primary anabolic effects of GH are mediated through hepatic IGF-1 production. GH-stimulated JAK2-STAT5 signalling in hepatocytes drives IGF-1 gene transcription and secretion. Circulating IGF-1 then acts on target tissues (muscle, bone, fat) through the IGF-1 receptor (IGF-1R), activating PI3K-Akt and MAPK-ERK pathways that drive protein synthesis, cell proliferation, and differentiation.
Direct Metabolic Effects: Separately from the IGF-1 axis, GH exerts direct metabolic effects on adipocytes (lipolysis via hormone-sensitive lipase activation), skeletal muscle (amino acid uptake, protein synthesis), and the liver (gluconeogenesis, glycogenolysis). These direct effects are insulin-antagonistic — elevated GH increases hepatic glucose output and reduces peripheral insulin sensitivity.
Pulsatile Secretion and Research Implications: Endogenous GH is secreted in pulses — predominantly during deep sleep — with low baseline concentrations between pulses. This pulsatile pattern is physiologically important; sustained GH elevation (as produced by long-acting GHRH analogs) produces different downstream effects than pulsatile administration. Recombinant HGH research protocols must consider pulse timing when designing studies examining physiological GH axis responses.
Research Applications
IGF-1 Axis Research: rhGH is the reference stimulus for IGF-1 production studies, allowing researchers to precisely control GH input and measure downstream IGF-1, IGFBP-3, and ALS responses in hepatic cell models and animal studies.
Body Composition Research: Extensive rodent and primate research has examined rhGH’s effects on lean mass accretion, fat mass reduction (particularly visceral adiposity), and the relative contributions of direct GH effects vs IGF-1-mediated effects to observed body composition changes.
Bone Biology: GH stimulates both periosteal bone expansion (direct effect) and endochondral ossification (IGF-1-mediated effect). rhGH is used in bone mineral density and fracture healing research models.
GH Deficiency Models: Hypophysectomised rodent models depleted of endogenous GH are used to study GH replacement dose-response relationships and tissue-specific GH sensitivity.
Comparison with GH Secretagogues: Research comparing the effects of direct rhGH administration vs GH secretagogues (ipamorelin, CJC-1295, sermorelin) on GH pulse profiles, IGF-1 kinetics, and downstream metabolic endpoints.
Anti-Aging Biomarker Research: Age-related GH/IGF-1 decline (somatopause) is studied using rhGH supplementation protocols in aged rodent models to identify reversible vs irreversible aging phenotypes.
Key Published Research
Primary publications relevant to HGH research. Full citations available via PubMed. QSC does not endorse or make claims based on this research.
Rudman et al. (1990)
“Effects of Human Growth Hormone in Men over 60 Years Old” — New England Journal of Medicine
Landmark clinical study examining rhGH effects on body composition in elderly men, documenting lean mass increase and fat mass reduction — establishing the framework for subsequent GH/IGF-1 aging research.
Le Roith et al. (2001)
“The Role of the Insulin-like Growth Factor-I Receptor in Cancer” — Annual Review of Medicine
Reviews the GH-IGF-1 axis mechanistic pathway, establishing the JAK2-STAT5-IGF-1 signalling framework fundamental to understanding rhGH research.
Veldhuis et al. (2006)
“Somatotropic Axis in the Human: Pulsatile Growth Hormone Secretion” — Endocrine Reviews
Comprehensive review of pulsatile GH secretion dynamics and their physiological significance for research protocol design.
Hoffman & Strasburger (2020)
“Management of Growth Hormone Deficiency” — Journal of Clinical Endocrinology & Metabolism
Reviews the clinical and preclinical evidence base for rhGH as a research reference compound in GH deficiency and replacement studies.
Research Protocol Reference
Model / Context
Dose Range
Route
Protocol Notes
Rodent IGF-1 Axis Study
1–4 mg/kg/day
Subcutaneous injection
Daily SC injection; blood sampling for IGF-1 and IGFBP-3 at 6, 12, 24 hours post-dose
Hypophysectomised Rodent
0.2–2 mg/kg/day
Subcutaneous injection
Dose-escalation protocols to establish GH replacement curves; endpoint-specific study durations of 2–8 weeks
In Vitro GHR Signalling
1–100 ng/ml
Added to cell culture medium
Used in hepatocyte, myocyte, and adipocyte signalling studies for JAK2-STAT5 pathway activation assays
Frequently Asked Questions
What is research-grade HGH?
Research-grade HGH (recombinant human growth hormone, somatropin) is a biosynthetically produced 191-amino acid protein identical in sequence to endogenous pituitary GH. It is used in preclinical and laboratory research examining the GH-IGF-1 axis, body composition, bone biology, and metabolic regulation. QSC research HGH is for laboratory use only.
What is the difference between HGH and HGH secretagogues?
Recombinant HGH directly replaces or supplements endogenous GH as the active protein. HGH secretagogues (ipamorelin, sermorelin, CJC-1295) stimulate the pituitary to produce and release its own GH. The key research distinction is that secretagogues preserve pulsatile GH patterns while direct HGH administration bypasses pituitary regulation entirely.
Why must reconstituted HGH not be frozen?
HGH is a protein — freezing reconstituted solution causes ice crystal formation that denatures the tertiary protein structure, destroying biological activity. Lyophilized (dry) HGH can be stored at -20°C; reconstituted HGH must stay at 4°C and be used within 14 days.
What purity does QSC HGH carry?
QSC research HGH is verified at ≥99% purity by HPLC and mass spectrometry. A Certificate of Analysis with Janoshik verification is published on the product page.
What IU sizes does QSC HGH come in?
QSC offers HGH in 10 IU, 15 IU, 24 IU, and 36 IU vials, plus 100 IU kits for higher-volume research protocols. View current stock via the product search link below.
Research Use Only: All products sold on qsc-usa.com are intended strictly for laboratory research purposes only. They are not approved for human consumption, veterinary use, or any other application. Researchers are responsible for understanding and complying with local regulations in their jurisdiction.
