Opioid peptides are small protein fragments that bind to opioid receptors in the body, producing effects similar to those of opioid drugs. They are naturally occurring and play a role in pain regulation, stress response, and emotional well-being. Examples of opioid peptides include endorphins, enkephalins, and dynorphins. These peptides are produced in the brain and other tissues, helping to modulate pain and promote feelings of pleasure. When released, they can reduce the perception of pain and induce a sense of euphoria, making them important in both physiological and psychological processes.