[D-Lys3]- GHRP- 6

[D-Lys3]-GHRP-6 is a ghrelin receptor (GHS-R1a) antagonist that weakly binds to the melanocortin receptor (Ki=26-120 μM). [D-Lys3] GHRP-6 binds to all four MC receptors using similar affinity, without binding to structurally related Met-enkephalin and functionally related GHuRH, as well as LHRH and somatostatin14. This (low affinity of GH release/enkephalin) can indicate that it does not interact with MC receptors at pharmacological concentrations. [DLys3] GHRP-6 binds to the MC1 receptor only with slightly higher affinity than GHRP-6.