Abstract
Opiate receptors play major roles in analgesic and euphoric effects of opiate drugs. Recent cloning of cDNAs encoding the rodent and human μ receptor revealed high homology between the predicted receptors but also some sequence differences. To determine if these sequence differences produced significant changes in ligand-selectivity profiles, we assessed these profiles in expressing COS and CHO cell lines using the agonist ligand [125I]IOXY-AGO (6β-[125Iodo]-3,14-dihydroxy-17-methyl-4,5α- epoxymorphinan). This ligand's high specific activity (2,200 Ci/mmol) and high affinity for μ opioid receptors generated high signal-to-noise ratio binding. The resulting ligand-selectivity profiles of the human and rat μ receptors reveal modest differences in affinities for morphine and naloxone in COS cells but not CHO cells. Ligand-selectivity profiles of the rat and human μ receptors were otherwise similar. Interesting differences between these data and data previously obtained with the peptide agonist [3H]DAMGO suggest that the peptide and alkaloid agonists may label different domains of the μ receptor.
Original language | English (US) |
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Pages (from-to) | 60-64 |
Number of pages | 5 |
Journal | Synapse |
Volume | 21 |
Issue number | 1 |
DOIs | |
State | Published - 1995 |
Externally published | Yes |
Keywords
- [I]IOXY-AGO
- [H]DAMGO
- CHO cells
- Opiate receptors
ASJC Scopus subject areas
- General Neuroscience
- Physiology
- Pharmacology