Growth hormone secretagogue receptor secretagogue receptor is activated, a variety of different intracellular signaling cascades can result, depending on the cell type in which the receptor is expressed. These intracellular signaling cascades include mitogen-activated protein kinase (MAPK)), protein kinase A (PKA), protein kinase B (PKB), also known as AKT), and AMP Activated Protein Kinase (AMPK) cascades. It is well-characterized that activating the growth hormone secretagogue receptor with ghrelin induces an orexigenic state, or general feeling of hunger. However, ghrelin may also play a role in behavioral reinforcement. Studies in animal models, found that food intake increased when ghrelin was specifically administered to just the
Melanocyte-stimulating hormone The different forms of MSH belong to a group called the melanocortins. This group includes ACTH, α-MSH, β-MSH, and γ-MSH; these peptides are all cleavage products of a large precursor peptide called proopiomelanocortin (POMC). α-MSH is the most important melanocortin for pigmentation. The different forms of MSH have the following amino acid sequences: Synthetic analogues of α-MSH have been developed for human use. Two of the better known are afamelanotide (melanotan I) in testing by Clinuvel Pharmaceuticals and bremelanotide by Palatin Technologies. Others include modimelanotide and setmelanotide. Melanocyte-stimulating hormone The melanocyte-stimulating hormones, known collectively as MSH, also known as melanotropins