Opiate activity of peptides derived from the three opioid peptide families on the rat vas deferens.
The inhibitory activity of opioid peptides derived from pro-opiomelanocortin (POMC), pro-enkephalin A and pro-enkephalin B (= pro-dynorphin) on the electrically evoked twitch of the rat vas deferens (RVD) was evaluated. The POMC-derived beta-endorphin exhibits the greatest potency on this preparation. In addition, all peptides derived from pro-enkephalin A show full agonistic activity with BAM-22P and peptide E as the most potent peptides. In contrast, the majority of peptides derived from pro-enkephalin B (= pro-dynorphin) were essentially inactive on this tissue. Moreover, no antagonistic properties of these peptides were demonstrable in this preparation; thus the opioid receptors present in the RVD (putative epsilon receptors) might not possess any particular affinity for the pro-enkephalin B derived peptides.
D000818:Animals; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011333:Pro-Opiomelanocortin / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects*; D001615:beta-Endorphin
D004723:Endorphins; D004745:Enkephalins; D011498:Protein Precursors; D011957:Receptors, Opioid; C029992:proenkephalin; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; C033660:preproenkephalin