Characterisation of the delta-opioid receptor on the hamster vas deferens

It has recently been reported that the hamster vas deferens contains only delta-opioid receptors. We have demonstrated that three delta-receptor agonists [D-Ala2, D-Leu5]enkephalin (DADLE), [D-Pen2, D-Pen5]enkephalin (DPDPE) and [D-Thr2, Leu5, Thr6] enkephalin (DTLET) appear to mediate their effects via the delta-receptor since they are readily reversed by the selective delta-receptor antagonist ICI 174864. In addition, a number of classical mu and k receptor compounds were devoid of activity in this preparation. However it was observed that some compounds such as etorphine and MR 2034 reported to possess delta-receptor affinity in other assay systems were weak or inactive on the hamster vas deferens.