title: Opioid peptides as intercellular messengers.
abstract: Opioid peptides are endogenous substances present in central nervous system and various tissues whose actions are mediated by opiate receptors. They belong to two different classes: short peptides like the two pentapeptides enkephalin and substances of higher molecular weight like beta-endorphin. It appears that these various peptides play a messenger role between cells, either as neurotransmitters in the case of enkephalins or as hormones in the case of beta-endorphin.
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000378:metabolism; D004723:Endorphins / Q000502:physiology*; D004745:Enkephalins / Q000378:metabolism / Q000502:physiology; D018377:Neurotransmitter Agents; D010902:Pituitary Gland / Q000378:metabolism; D010907:Pituitary Hormones; D011957:Receptors, Opioid / Q000378:metabolism
chemical_list: D004723:Endorphins; D004745:Enkephalins; D018377:Neurotransmitter Agents; D010907:Pituitary Hormones; D011957:Receptors, Opioid