The C-terminal dipeptide of beta-endorphin: a neuropeptide with inhibitory activity.

Glycylglutamine, the C-terminal dipeptide of beta-endorphin, has previously been shown to be present in porcine pituitary. Evidence is given that this dipeptide occurs in ovine brain stem where its concentration was shown to be similar to that of the complementary fragments of beta-endorphin determined by chromatography and radioimmunoassay. Using the technique of microiontophoresis an inhibitory activity of the dipeptide was demonstrated on neurones located in the reticular formation of rat brain stem.