Source comparison
Molecular Mechanisms: Myostatin Inhibition vs GH Pulse Amplification
Follistatin-344 comprises 344 amino acids forming a glycoprotein that binds with high affinity (Kd ~100 pM) to myostatin. A TGF-beta superfamily member that normally signals muscle cells to stop proliferating. By sequestering myostatin extracellularly, follist
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- Follistatin-344 comprises 344 amino acids forming a glycoprotein that binds with high affinity (Kd ~100 pM) to myostatin. A TGF-beta superfamily member that normally signals muscle cells to stop proliferating. By sequestering myostatin extracellularly, follistatin prevents it from binding to activin type II receptors (ActRIIB) on muscle fiber membranes, which would otherwise trigger SMAD2/3 phosphorylation and downstream transcriptional suppression of muscle protein synthesis. Animal studies demonstrate that follistatin gene delivery increased muscle mass 35% in mice and 15–20% in non-human primates without exogenous anabolic agents.
- Sermorelin (also called GRF 1-29 because it contains the first 29 amino acids of growth hormone-releasing hormone) binds to GHRH receptors on somatotroph cells in the anterior pituitary. This binding activates adenylyl cyclase, raising intracellular cAMP, which triggers calcium influx and growth hormone granule exocytosis. The released GH follows the body's natural pulsatile pattern. Typically peaking 30–60 minutes post-injection and returning to baseline within 2–3 hours. Clinical trials in adults with GH deficiency showed Sermorelin 100mcg subcutaneously increased mean nocturnal GH secretion by 2.6-fold compared to placebo.
- The critical distinction: follistatin acts locally at the tissue level where it's expressed or administered; Sermorelin requires an intact hypothalamic-pituitary-IGF-1 axis to produce effects. Our experience supplying research-grade peptides shows investigators choosing follistatin when studying muscle regeneration post-injury, and Sermorelin when examining age-related GH decline or metabolic effects mediated through IGF-1.