Using binding approaches, we have confirmed the high selectivity of [D-Ser2,Leu5]enkephalin-Thr6 (DSLET) to delta, as opposed to morphine-preferring (mu2) sites in rat brain. However, detailed experiments studies indicate that this ligand also labels mu1 sites with very high affinity. Saturation studies of 3H-DSLET binding reveal curvilinear plots. Treating tissue with naloxonazine to block mu1 sites, eliminates the higher affinity binding component. Competition studies of the other peptites against 3H-DSLET and 3H[D-Ala2, MePhe4,Gly(ol)5] enkephalin (3H-DAMPGO) binding also implied high affinity binding of these peptides to mu1 sites. The ability of these peptides to interact with mu1 sites may help explain some of their pharmacological actions.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)