Comparison of mu opioid receptor binding on intact neuroblastoma cells with guinea pig brain and neuroblastoma cell membranes

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 260; no. 1; pp. 9 - 15
• Main Author: TOLL, L
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Pharmacology and Experimental Therapeutics 01.01.1992
• Subjects: Animals; binding; Biological and medical sciences; brain; Brain - metabolism; Brain - ultrastructure; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell receptors; Cell structures and functions; comparison; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Kinetics; Mammalia; Molecular and cellular biology; Narcotic Antagonists; Neuroblastoma - metabolism; Neuroblastoma - pathology; Neuroblastoma - ultrastructure; neuroblastoma cells; Neuropeptide receptors; opiates; Pertussis Toxin; plasma membranes; receptors; Receptors, Opioid - metabolism; Receptors, Opioid - physiology; Receptors, Opioid, mu; Somatostatin - analogs & derivatives; Somatostatin - metabolism; Tumor Cells, Cultured; Virulence Factors, Bordetella - pharmacology; Cell culture; Rodentia; Central nervous system; Neuroblastoma; In vitro; Opioid peptide; Opiate receptor μ; Vertebrata; Biological fixation; Mammalia; Guinea pig; Plasma membrane; Brain (vertebrata)
• ISSN: 0022-3565; 1521-0103

To better understand opioid binding parameters found in situ, binding studies were conducted to mu-opioid receptors on intact SH-SY5Y neuroblastoma cells and compared with binding to SH-SY5Y membrane and guinea pig brain membrane preparations. The mu-selective peptide antagonist [3H]D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) was used for the binding studies. The fact that CTOP is an antagonist and hydrophilic is important for binding to be achieved using intact cells. In intact cells, using a physiological buffer, there appears to be only a low affinity "agonist" conformation of the receptor. This is in contrast to binding in either brain or SH-SY5Y membranes in Tris buffer, in which high-affinity agonist binding was prevalent. As expected from the binding profiles, pertussis toxin treatment of cells has no effect on binding to intact cells, but significantly decreases affinity of agonists to cell membranes. In intact cells, binding appears to be to a single site and a single state of the mu receptor. Although in membrane preparations inhibition curves are shallow, with slope factors less than 1.0 for many agonists, on intact cells agonist inhibition curves are very steep, with slope factors slightly greater than 1.0.