Muscle Mass & Growth Factors

The "Muscle mass and growth factors" series operates at one specific level - endogenous growth hormone secretion from the pituitary via pulsatile stimulation, not exogenous replacement. The distinction matters: pulsatile GH preserves the physiological hypothalamic somatostatin response and doesn't induce the GHR receptor down-regulation seen with high-dose recombinant HGH.

Ipamorelin is a pentapeptide and selective ghrelin receptor (GHSR-1a) agonist - unlike GHRP-6 and Hexarelin, it doesn't raise cortisol or prolactin at tested doses (Raun et al., Eur J Endocrinol 1998). CJC-1295 is a modified GHRH(1-29) with DAC (Drug Affinity Complex) extending half-life from ~7 minutes to ~8 days (Teichman et al., J Clin Endocrinol Metab 2006). The two act on different receptors (GHSR-1a + GHRH-R), so in combination they produce greater GH-pulse amplitude than either alone - the literature reports a 7-15x rise in 24-hour GH AUC in healthy adults (Sigalos & Pastuszak, Sex Med Rev 2018).

MGF (Mechano-Growth Factor) is an alternative splice variant of IGF-1 triggered by mechanical loading of muscle fibers - unlike systemic IGF-1 it acts locally, activating satellite cells for myonuclear donation (Goldspink, J Anat 1999). Recombinant HGH marks the clinical edge of the category - supplementation under confirmed somatotropic deficiency, not performance enhancement. For researchers, the choice depends on whether the question is "how is the GH-pulse architecture regulated" (Ipamorelin + CJC-1295) or "how does local muscle damage repair" (MGF).

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