Hamster vas deferens contains delta-opioid receptors

Electrical field stimulation of the hamster, isolated vas deferens produces regular contractions that are unaffected by opioid-receptor agonists which are selective for the mu- or kappa-receptor types. However, agonists which show a selectivity for the delta-opioid receptor produce dose-related inhibitions of the stimulation-evoked contractions. Response of delta-opioid receptor agonists are antagonized in a competitive fashion by the selective delta-receptor antagonist ICI 174864, and also by naloxone. The "kappa-opioid-agonist" benzomorphans, bremazocine and ethylketocyclazocine are antagonists in the hamster vas deferens; bremazocine is particularly potent in this regard. In conclusion, the hamster, isolated vas deferens may contain only delta-opioid receptors and provides a simple and specific test for the assay of activity at the delta-opioid receptor.