Dynorphin: a possible modulatory peptide on morphine or beta-endorphin analgesia in mouse

Dynorphin-(1-13), but not dynorphin-(1-9) has been shown to have significant effects on opiate and beta-endorphin-induced analgesia despite not having any appreciable analgesic activity itself. Dynorphin had no effect on Sandoz FK33824 compound-induced analgesia.