PT-141 or Bremelanotide is the generic term for a research peptide being studied for its possible use in helping to improve sexual dysfunction in both men (erectile dysfunction or impotence) and women (sexual arousal disorder). PT-141 was developed from the tanning peptide Melanotan 2, which is a synthetically produced variant of a peptide hormone naturally produced in the body that stimulates melanogenesis that is known as alpha-Melanocyte stimulating hormone. MSH, activates certain melanocortin receptors in the process of exerting its effects. Indeed, MSH also exerts potent influence over lipid metabolism, appetite, and sexual libido. Resultantly, PT-141 has been shown in studies to exhibit libido-enhancing effects by activating the melanocortin receptors MC1R and MC4R, but not skin tanning. Melanotan 1 and Melanotan 2 have been researched for their use in protecting against the harmful effects of ultraviolet radiation from sunlight due to their melanogenesis-stimulating properties.