The effects of delta-opioid receptor agonists on synaptic transmission in hamster submandibular ganglion

The effects of agonists for delta-opioid receptors on synaptic transmission in hamster submandibular ganglion were studied in vitro, using an intracellular recording technique. [Met5]enkephalinamide (17 microM), [D-Ser2¿Leu-enkephalin-Thr (14 microM) and [D-Pen2, D-Pen5]enkephalin (10 microM), delta selective agonists caused reversible depression of the fast EPSP amplitude in 10 of 30 cells tested. The inhibitory actions of [D-Pen2, D-Pen5]enkephalin were antagonized by ICI 174,864, a delta selective antagonist. Naloxon a non-selective antagonist and ICI 174,864 both also potentiated the fast EPSP amplitude in 5 of 11 cells tested.