Opioid peptide
（重定向自Opioid Peptides）
![Structural correlation between met-enkephalin, an opioid peptide, (left) and morphine, an opiate drug, (right)](/Images/godic/202501/31/Correlación_estructural_entre_las_encefalinas_y_la_morfina.svg0151.png")
Opioid peptides are short sequences of amino acids that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble those of opiates. Brain opioid peptide systems are known to play an important role in motivation, emotion, attachment behaviour, the response to stress and pain, and the control of food intake.