Opioid peptides are a class of endogenous peptides that interact with opioid receptors in the body. These peptides are involved in a wide range of physiological processes, including pain modulation, stress response, and reward pathways. Opioid peptides are derived from larger precursor proteins called proopiomelanocortin and prodynorphin, and are released in response to different stimuli. Research in the field of opioid peptides focuses on understanding their role in various conditions such as chronic pain, addiction, and mood disorders. This research also investigates the potential therapeutic applications of opioid peptides, such as developing new analgesic drugs with fewer side effects than traditional opioids. Additionally, studies on opioid peptides aim to uncover the mechanisms of opioid receptor signaling and explore novel targets for the treatment of opioid-related disorders.