title: The role of calmodulin in opioid-induced changes in the phosphorylation of rat striatal synaptic membrane proteins.
abstract: Chronic morphine treatment of rats decreased the level of phosphorylation of synaptic membrane proteins of the striatum assayed in vitro. Although the patterns of phosphorylated proteins separated on SDS-gel electrophoresis from morphine-tolerant rats resembled patterns produced by lowering Ca2+ levels in the assay, supplementation of the protein kinase assay with Ca2+ and its binding protein, calmodulin, did not restore full kinase activity. The addition of methadone or etorphine to the protein kinase in vitro however, was able to block the Ca2+-calmodulin stimulation of phosphorylation in both synaptic membranes and intact synaptosomes. These data suggest that opioids produce an irreversible (or slowly reversible) defect in the Ca2+-dependent protein kinase system of striatal membranes.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D003342:Corpus Striatum / Q000378:metabolism*; D005048:Etorphine / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008691:Methadone / Q000494:pharmacology*; D009019:Morphinans / Q000494:pharmacology*; D009020:Morphine / Q000494:pharmacology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D008565:Membrane Proteins; D009019:Morphinans; D005048:Etorphine; D009020:Morphine; D011494:Protein Kinases; D002118:Calcium; D008691:Methadone