Open AccessMorphine sulfate stimulates the adenylate cyclase in mouse caudate nuclei.
Author(s) -
Lei-Han Tang,
George C. Cotzias
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.3.1546
Subject(s) - adenylate kinase , cyclase , (+) naloxone , dopamine , morphine , chemistry , caudate nucleus , stimulation , medicine , endocrinology , dopamine receptor , receptor , opioid , biochemistry , biology
The effect of several concentrations of morphine on the activity of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing): EC 4.6.1.1.] was measured in homogenates of caudate nuclei of mice. Morphine stimulated the enzyme at 500 micron and inhibited slightly at 5 micron. Morphine stimulation was blocked by naloxone. Depending on its dose, morphine also increased or decreased the stimulating effect of dopamine on the dopamine-sensitive adenylate cyclase activity of caudate homogenate. Like dopamine, morphine'e effect on the adenylate cyclase activity was increased or decreased, respectively, by pretreating the animals with poly(I).poly(C) or with chloramphenicol. Thus, both dopamine and morphine appear to act on the same receptor. This "new" receptor differs from the one described by Snyder et al. and others, who demonstrated only binding affinity and no enzymatic activity. These data indicate that certain functions of the opiates might be mediated through the dopamine-sensitive adenylate cyclase of the caudate nuclei, which are the dopamine receptors in the brain.