title: Interaction of endogenous opioid peptides and other drugs with four kappa opioid binding sites in guinea pig brain.
abstract: Guinea pig brain membranes depleted of mu and delta receptors by pretreatment with the site-directed acylating agents, 2-(4-ethoxybenzyl)-1- diethylaminoethyl-5-isothiocyanatobenzimidazole.HCl (BIT) and N-phenyl-N-[1-(2-(4-isothiocyanato)phenethyl)-4- piperidinyl]-propanamide.HCl (FIT), were used in this study to test the hypothesis that guinea pig brain possesses subtypes of kappa receptors. Pretreatment of membranes with either (-)-(1S,2S)-U50,488 or the kappa selective acylating agent, (1S,2S)-trans-2-isothiocyanato-N-methyl-N-[2-(1- pyrrolidinyl)cyclohexyl]benzeneacetamide, caused a wash-resistant inhibition of kappa 1 binding sites labeled by [3H]U69,593 binding, but not kappa 2 binding sites labeled by [3H]bremazocine. Binding surface analysis of [3H]bremazocine binding resolved two binding sites, termed kappa 2 and kappa 2b, present at densities of 212 and 225 fmol/mg protein, which had low affinity for (-)-(1S,2S)-U50,488 and U69,593. The kappa 2b site had high affinity for beta-endorphin(1-31) (Kd = 5.5 nM) and [D-Ala2,D-Leu5]enkephalin (Kd = 14 nM), and lower affinity for [D-Ala2-MePhe4,Gly-ol5]enkephalin (Kd = 147 nM) and [Leu5]enkephalin (Kd = 46.0 nM). Binding surface analysis of [3H]U69,593 binding also resolved two binding sites, termed kappa 1a and kappa 1b, present at densities of 6.0 and 40.0 fmol/mg protein. The kappa 1a binding site was characterized by very high affinity for alpha-neoendorphin. Quantitative autoradiographic studies demonstrated that kappa 2a and kappa 2b binding sites are heterogeneously distributed in guinea pig brain, and that the anatomical distribution of kappa 1 binding sites reported in the literature is different from that observed in this study for the kappa 2 binding sites. Viewed collectively, these data provide evidence for four kappa receptor subtypes in guinea pig brain.
authors.affiliation: Unit on Receptor Studies, NIMH, Bethesda, MD 20892.
authors.forename: R B
authors.initials: RB
authors.lastname: Rothman
authors.forename: V
authors.initials: V
authors.lastname: Bykov
authors.forename: B R
authors.initials: BR
authors.lastname: de Costa
authors.forename: A E
authors.initials: AE
authors.lastname: Jacobson
authors.forename: K C
authors.initials: KC
authors.lastname: Rice
authors.forename: L S
authors.initials: LS
authors.lastname: Brady
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000345:Affinity Labels; D000704:Analysis of Variance; D000818:Animals; D001345:Autoradiography; D044482:Benzeneacetamides; D001575:Benzomorphans / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D003627:Data Interpretation, Statistical; D004723:Endorphins / Q000378:metabolism*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism; D006168:Guinea Pigs; D008024:Ligands; D008297:Male; D008433:Mathematics; D008566:Membranes / Q000378:metabolism; D009271:Naltrexone / Q000031:analogs & derivatives / Q000378:metabolism; D011759:Pyrrolidines / Q000378:metabolism; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa; D013696:Temperature
chemical_list: D000345:Affinity Labels; D044482:Benzeneacetamides; D001575:Benzomorphans; D004723:Endorphins; D004745:Enkephalins; D008024:Ligands; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; C043394:3-acetyl-6-deoxy-6-fluoronaltrexone; C027248:bremazocine; C045444:U 69593