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Interaction of endogenous opioid peptides and other drugs with four kappa opioid binding sites in guinea pig brain
Quantitative autoradiographic studies demonstrated that kappa 2a and kapp 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 kappa2 binding sites. Expand
Interaction of opioid peptides and other drugs with multiple kappa receptors in rat and human brain. Evidence for species differences
Quantitative examination of [3H]bremazocine binding resolved two kappa 2 binding sites in both rat and human brain whose ligand selectivity patterns differed from that of the guinea pig, suggesting that there may be considerable variation in the ligand recognition site of kappa receptor subtypes among mammalian species. Expand
Pharmacological activities of optically pure enantiomers of the κ opioid agonist, U50,488, and its cis diastereomer: evidence for three κ receptor subtypes
De Costa et al. (FEBS Lett. 223, 335; 1987) recently described the synthesis of optically pure enantiomers of (±)-trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamideExpand
Chronic haloperidol treatment up-regulates rat brain PCP receptors.
Probing the opioid receptor complex with (+)-trans-SUPERFIT. II. Evidence that μ ligands are noncompetitive inhibitors of the δ cx opioid peptide binding site
The present study compared the properties of the delta cx binding site present in brain membranes pretreated with (+)-trans-SUPERFIT with the properties in untreated membranes, and found that whereas mu-preferring drugs were noncompetitive inhibitors of [3H][D-Ala2,Leu5]enkephalin binding to the Delta cx site, delta- preferring Drugs were competitive inhibitors. Expand
Evidence for four opioid kappa binding sites in guinea pig brain.
beta-FNA binds irreversibly to the opiate receptor complex: in vivo and in vitro evidence.
beta-Funaltrexamine (beta-FNA) is an alkylating derivative of naltrexone. Considerable data support its use as an irreversible mu receptor antagonist. However, pretreatment of rats with beta-FNAExpand
Chronic administration of morphine and naltrexone up-regulate[3H][d-ala2,d-leu5]enkephalin binding sites by different mechanisms
The experiments reported in this paper suggest that chronic administration of morphine and naltrexone up-regulate binding sites for [3H][D-ala2,D-leu5]enkephalin through different mechanisms, and that the lower affinity binding sites which are up-regulated by chronicadministration of opioids might differ biochemically from the lower binding sites present in membranes treated with placebo. Expand
Chronic administration of morphine and naltrexone up-regulate mu-opioid binding sites labeled by [3H][D-Ala2,MePhe4,Gly-ol5]enkephalin: further evidence for two mu-binding sites.
This study test and confirm the hypothesis that the irreversible mu-antagonist beta-funaltrexamine (FNA) selectively alkylates the opiate receptor complex, using sensitivity to FNA to define the mu cx binding site, and the implications for models of the opioid receptors and the mechanism(s) of tolerance and dependence are discussed. Expand
Upregulation of the opioid receptor complex by the chronic administration of morphine: A biochemical marker related to the development of tolerance and dependence
Evidence is provided that naltrex-one-induced upregulation of the opioid receptor complex might occur indirectly as a consequence of interactions at beta-funaltrexamine-insensitive opioid receptors and that morphine- induced upregulation (increased Bmax) of the opioids receptor complex is a relevant in vitro marker related to the development of tolerance and dependence. Expand