DIFFERENTIAL INHIBITORY EFFECTS OF ASCORBIC-ACID ON THE BINDING OF DOPAMINE AGONISTS AND ANTAGONISTS TO NEOSTRIATAL MEMBRANE PREPARATIONS - CORRELATIONS WITH BEHAVIORAL-EFFECTS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 34  (3) , 409-421
Abstract
Ascorbic acid was a potent inhibitor of the binding of both dopamine agonists [3H-dopamine and 3H-ADTN (2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene, a cyclic dopamine analog)] and also of dopamine antagonists (3H-spiroperidol and 3H-domperidone) to [rat] neostriatal membrane preparations. Against dopamine agonists, ascorbic acid caused a dose-dependent inhibition of binding with about 90% effect at 6 mM ascorbic acid. Against dopamine antagonists there was a U-shaped dose response curve for ascorbic acid. That is, 6 mM ascorbic acid caused no significant inhibition, while 0.006 mM caused a slight inhibition and intermediate concentrations caused extensive inhibition. Almost identical inhibitory effects were obtained with sodium ascorbate. In other experiments, 500 mg/kg of ascorbic acid given to mice 1 h prior to the dopamine releasing agent d-amphetamine, was able to greatly attenuate the increase in locomotor activity usually seen after amphetamine. These latter data may have important implications for a possible role for ascorbic acid in dopaminergic neurotransmission.