Growth Hormone and Aging Endotext NCBI Bookshelf Frontiers Exploring the beneficial effects of GHK Cu on an experimental model of colitis and the underlying mechanisms GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with How GHK Peptide Works Signaling GHK acts as a switch for skin repair: Interacts with adenosine receptors reduces inflammation Activates MAPK ERK, PI3K Akt, TGF pathways Stimulates fibroblasts & keratinocytes boosts collagen, elastin Frontiers Exploring the beneficial effects of GHK Cu on an experimental model of colitis and the underlying mechanisms