Melanotan II (MT2) is a stimulating peptide that induces skin tanning. Melanocyte Stimulating Hormones (MSH) are a class of peptide hormones produced in the intermediate lobe of the pituitary gland that stimulates pigment cells (melanocytes) in the skin and hair to produce and release melanin that leads to darker skin and hair. Melanotan II increases melanin production via stimulation of the pigment cells called melanocytes