title: The possible role of protein phosphatase 2A in the sodium sensitivity of the receptor binding of opiate antagonists naloxone and naltrindole.
abstract: In striatal membrane preparation used for receptor binding experiments high levels of protein phosphatase 1 and 2A activities were detected using [32P]phosphorylase a as substrate. Sodium chloride decreased the activity of protein phosphatase 2A and increased the activity of protein phosphatase 1 in a concentration-dependent manner. Sodium chloride facilitated the saturation binding of naloxone and naltrindole in rat striatal membrane preparation preincubated with ATP (50 microM) and MgCl2 (5 mM). Preincubation with calyculin A (1 nM) further increased the binding of naloxone. Addition of okadaic acid in a concentration of 2 nM, which is specific for the inhibition of protein phosphatase 2A, augmented the number of binding sites of naloxone or naltrindole. The results suggest a protein phosphatase-dependent regulation of the binding of opiate ligands in the striatum.
authors.affiliation: Department of Medical Chemistry, University Medical School of Debrecen, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Murányi
authors.forename: P
authors.initials: P
authors.lastname: Gergely
authors.forename: G M
authors.initials: GM
authors.lastname: Nagy
authors.forename: M I
authors.initials: MI
authors.lastname: Fekete
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000737:chemistry / Q000201:enzymology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008387:Marine Toxins; D009270:Naloxone / Q000378:metabolism / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000378:metabolism / Q000494:pharmacology*; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010762:Phosphorylase a / Q000494:pharmacology; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism; D012680:Sensitivity and Specificity; D012965:Sodium Chloride / Q000494:pharmacology*; D013379:Substrate Specificity; D014316:Tritium
chemical_list: D004791:Enzyme Inhibitors; D008387:Marine Toxins; D009292:Narcotic Antagonists; D010080:Oxazoles; D010761:Phosphorus Radioisotopes; D011957:Receptors, Opioid; D014316:Tritium; D009270:Naloxone; D012965:Sodium Chloride; D009271:Naltrexone; C059041:calyculin A; D010762:Phosphorylase a; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; C055382:naltrindole