Description
HGH 191AA (also Somatropin) is a recombinant form of human growth hormone with the complete 191-amino acid sequence identical to the endogenously produced variant from the pituitary. Manufactured via recombinant DNA technology, the substance serves as a research reference compound for studies on GH receptor activation, signal transduction and endocrine pathways.
Per study reports, HGH 191AA is used in a wide variety of study designs: investigations of growth hormone receptor binding, JAK2/STAT5 signal transduction, protein synthesis pathways, the IGF-1 axis and metabolic adaptation. Due to the precise sequence match with the natural hormone, the compound also serves as a reference standard in bioassays and immunoassays.
In preclinical research settings, effects on cell proliferation, lipid metabolism, muscle physiology, bone density and regenerative pathways are investigated. Action occurs through binding to growth hormone receptors (GHR) on target cells, followed by activation of Janus kinases and downstream transcription factors. IGF-1 is considered the central downstream mediator.
HGH 191AA is delivered lyophilized and differs pharmacologically from secretagogues such as CJC-1295 or Ipamorelin: while secretagogues stimulate the endogenous GH axis, here the substance is directly administered. This has consequences in research setups for natural pulsatility and HPA axis regulation.
You can order HGH 191AA in 10-vial packs from 8 to 50 iu per vial.
This information is for research and educational purposes only. No medical recommendations.
Risks & Safety
HGH 191AA is considered well characterized and largely well tolerated per study reports. Unlike GH secretagogues, here the hormone is directly administered, which makes the effects more pronounced and less tied to the natural feedback loop.
Observed in research and user reports:
- Injection site: mild redness, pressure or transient irritation at the injection site is the most common observation with subcutaneous use.
- GH-typical effects: as is common with direct GH administration, the literature describes water retention as well as numbness or tingling in the hands (carpal-tunnel-type symptoms) and joint discomfort, usually dose-dependent.
- Glucose metabolism: elevated GH levels can raise fasting blood glucose and reduce insulin sensitivity in studies - tending to be more pronounced with direct administration than with secretagogues.
- Loss of pulsatility: direct substance administration bypasses the natural pulsatile GH secretion and can modulate endogenous axis regulation.
- No long-term data: robust long-term human studies on research use do not exist. The profile rests primarily on short-term studies and anecdotal experience.
This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Human growth hormone and extracellular domain of its receptor: crystal structure of the complex - Science 1992: Crystal structure of the complex between hGH and the extracellular domain of its receptor, in which one hormone molecule binds two receptor molecules.
- Mechanism of activation of protein kinase JAK2 by the growth hormone receptor - Science 2014: Mechanism study on how the GH receptor activates the kinase JAK2 after hormone binding, the starting point of the JAK/STAT signaling pathway.
- Normal growth and development in the absence of hepatic insulin-like growth factor I - PNAS 1999: In mice without IGF-1 production in the liver, growth was normal despite sharply reduced IGF-1 levels in the blood, pointing to the role of locally produced IGF-1.
- Effects of growth hormone on glucose, lipid, and protein metabolism in human subjects - Endocrine Reviews 2009: Review of the effects of GH on glucose, lipid and protein metabolism in humans, including increased lipolysis and reduced insulin sensitivity.
- Systematic review: the safety and efficacy of growth hormone in the healthy elderly - Annals of Internal Medicine 2007: Systematic review of randomized trials in healthy older adults, describing small changes in body composition and more frequent adverse effects such as edema, joint discomfort and carpal tunnel syndrome.
