Hexarelin

One methyl group, measurable difference

Hexarelin differs from GHRP-6 only by methylation of the indole nitrogen of the D-tryptophan at position 2. Structure–activity studies attribute the resulting gain in potency and metabolic stability to that substitution, which hinders enzymatic attack and alters how the residue packs into the receptor's hydrophobic pocket. The pair is a frequently cited example of how a minimal modification changes pharmacology within a conserved scaffold.

GHS-R1a signalling and desensitisation

As a GHS-R1a agonist hexarelin drives Gq-coupled phospholipase C activity, inositol trisphosphate generation and calcium mobilisation in somatotroph preparations. Repeated-exposure studies in animal models have examined attenuation of the growth hormone response over time, making hexarelin a common tool for investigating receptor desensitisation and downregulation kinetics.

Cardiac and CD36 research

• Binding studies identifying CD36 as a hexarelin target in cardiac membranes, distinct from GHS-R1a
• Isolated heart and cardiomyocyte preparations examining contractility and ischaemia-reperfusion endpoints
• Experiments in hypophysectomised animal models, used to separate growth hormone-dependent from growth hormone-independent effects

Position within the GHRP family

Store sealed vials at −20 °C, protected from light and moisture, and equilibrate to room temperature before opening to avoid condensation. Reconstitute with bacteriostatic or sterile water added slowly down the vial wall and swirl gently until the cake dissolves; shaking causes foaming and shear loss. The methylated tryptophan and second tryptophan residue make solutions light-sensitive, so use amber vials or foil. Keep reconstituted material at 2–8 °C, labelled with lot and preparation date, and aliquot instead of repeated freeze–thaw cycles. Handle with gloves under your laboratory's standard chemical hygiene procedures.