Gly-His-Lys

During human aging there is an increase in the activity of inflammatory, cancer promoting, and tissue destructive genes plus a decrease in the activity of regenerative and reparative genes. The human blood tripeptide GHK possesses many positive effects but declines with age. It improves wound healing and tissue regeneration (skin, hair follicles, stomach and intestinal linings, and boney tissue), increases collagen and glycosaminoglycans, stimulates synthesis of decorin, increases angiogenesis, and nerve outgrowth, possesses antioxidant and anti-inflammatory effects, and increases cellular stemness and the secretion of trophic factors by mesenchymal stem cells. Recently, GHK has been found to reset genes of diseased cells from patients with cancer or COPD to a more healthy state. Cancer cells reset their programmed cell death system while COPD patients' cells shut down tissue destructive genes and stimulate repair and remodeling activities.

Three decades of extensive research on biological activity of natural tripeptide Gly-His-Lys has established the substructure for development of its novel derivatives which give hope for widening the application in the field of medicine and dermatology. Synthetic approaches to obtain Gly-His-Lys and its modifications provide both classical solution method and solid phase peptide synthesis, usage of different protecting groups and methods of peptide bond formation. In our present review, we emphasize on the methods of the synthesis described in the literature and present the aspects of Gly-His-Lys structure modifications that played a key role in scientific research.

Intraperitoneal administration of tripeptide Gly-His-Lys to male rats in doses of 0.5, 5, and 50 μg/kg 12 min before the start of the experiment produced an anxiolytic effect in the elevated plus maze test manifested in an increase in the time spent in open arms and shortened time spent in the closed arms. The anxiolytic effect was most pronounced after injection of 0.5 μg/kg peptide and decreased with increasing the dose of the peptide. Replacement of L-lysine with D-lysine in the tripeptide molecule was accompanied by a significant weakening of the neurotropic effects in all studied doses. Attachment of D-alanine to N- or C-terminus of Gly-His-Lys peptide leveled its anxiolytic action in all doses; significant changes in some measures of increased anxiety after administration at 50 μg/kg were found.

Transforming growth factor β (TGF-β) is a cytokine involved in a wide variety of biological process- es such as cell growth, differentiation and proliferation, apoptosis and regulation of the immune response. It has an important role in wound healing process, fibrosis and scar tissue formation. Similarly to TGF-β1, insulin growth factor (IGF) family is expressed locally in response to tissue injury. Treatment of dermal fibroblasts with IGF-1 caused a substantial induction of TGF-β1 mRNA. Not a great deal of research so far has focused on IGF-2. Much attention has been focused on the tripeptides such as Gly-His-Lys (GHK) and their copper complexes, which have a high activity and good skin tolerance. Recent data suggest that their physiological role has been related to the process of wound healing, tissue repair and skin inflammation. In the present study, the influence of 1 nM solutions of GHK, GHK-Cu and CuCl2, on IGF-2-dependent TGF-β1 secretion in normal human dermal fibroblasts cells was investigated.