PT  - JOURNAL ARTICLE
AU  - K M Standifer
AU  - J Cheng
AU  - A I Brooks
AU  - C P Honrado
AU  - W Su
AU  - L M Visconti
AU  - J L Biedler
AU  - G W Pasternak
TI  - Biochemical and pharmacological characterization of mu, delta and kappa 3 opioid receptors expressed in BE(2)-C neuroblastoma cells.
DP  - 1994 Sep 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1246--1255
VI  - 270
IP  - 3
4099  - http://jpet.aspetjournals.org/content/270/3/1246.short
4100  - http://jpet.aspetjournals.org/content/270/3/1246.full
SO  - J Pharmacol Exp Ther1994 Sep 01; 270
AB  - Total opioid binding in the human neuroblastoma cell line BE(2)-C has a density similar to that found in brain, with a Bmax value of 383 +/- 60 fmol/mg protein and a KD of 0.4 +/- 0.07 nM for the nonselective opioid antagonist 3H-diprenorphine. Selective assays reveal a binding distribution of mu (38%), delta (16%) and kappa 3 (43%) opioid receptors. There is no observable kappa 1 or kappa 2 binding. The sum of the Bmax values in the selective binding assays (370 +/- 39 fmol/mg protein) approximates closely that observed with 3H-diprenorphine, suggesting that mu, delta and kappa 3 sites account for most of the binding. The binding selectivities of various opiates and opioid peptides in the BE(2)-C cells are similar to those in rat brain. Delta and mu binding are defined easily by traditional selective ligands. The binding profiles also distinguish clearly mu from kappa 3 binding. The selective mu ligand DAMGO competes with mu binding over 35-fold more potently than kappa 3 binding, whereas morphine shows a 10-fold selectivity. Functionally, selective mu, delta and kappa 3 agonists inhibit forskolin-stimulated cAMP accumulation through distinct receptor mechanisms that are pertussis toxin-sensitive. In addition to demonstrating that BE(2)-C cells provide a useful model system for studying mu, kappa 3 and delta receptors, these studies confirm that kappa 3 receptors represent a pharmacologically distinct receptor class in this cell line.