We have previously reported that particulate fractions from the brain of Bufo marinus bind enkephalins and their analogues very poorly, suggesting a low level or virtual absence of δ receptors. A detailed examination has revealed that the predominant opiate receptor subclass in toad brain is of the benzomorphan preferring type. This subclass, though similar to the κ and σ binding sites found in mammalian brain, seems to have a higher affinity for μ-preferring ligands than its mammalian counterpart. Based in our findings, we estimate that toad brain contains 60-70% κ/σ sites, 20-30% μ sites and very few if any δ sites.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)