Modulation of the N-methyl-D-aspartate receptor by haloperidol: NR2B-specific interactions.
The dopaminergic antagonist haloperidol has an eight- to 10-fold higher affinity for NMDA receptors containing the NR2B (epsilon2) subunit, showing the same subunit specificity as ifenprodil, polyamines, and magnesium. In the present study, we have compared the effects of mutations altering polyamine and ifenprodil sensitivity on haloperidol sensitivity of NMDA receptors. As seen for spermidine stimulation, high-affinity haloperidol inhibition is governed by the region around amino acid 198, based on results from chimeric murine NR2A/NR2B (epislon1/epsilon2) receptors. Mutation of epsilon2E201 in this region to asparagine or arginine causes a 10-fold decrease in the ability of haloperidol to inhibit 125I-MK-801 binding. Epsilon2E201 does not govern the interactions of ifenprodil, because all of the mutants at epsilon2E201 exhibited wild-type affinity for ifenprodil. Mutation of epsilon2R337 causes a 400-fold loss in apparent affinity for ifenprodil but does not change the effects of haloperidol. The structural determinants of spermidine stimulation do not perfectly match those for haloperidol inhibition, as mutations of E200 remove haloperidol inhibition but do not alter polyamine stimulation. The present results thus demonstrate that although spermidine, haloperidol, and ifenprodil share subunit selectivity and overlapping pharmacology, they also have specific structural determinants.
Gallagher
M J
MJ
Department of Neurology, University of Pennsylvania School of Medicine and Children's Seashore House, Philadelphia, USA.
Huang
H
H
Lynch
D R
DR
D000595:Amino Acid Sequence; D001667:Binding, Competitive / Q000502:physiology; D002678:Chimera; D016291:Dizocilpine Maleate / Q000037:antagonists & inhibitors / Q000378:metabolism; D018492:Dopamine Antagonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010880:Piperidines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013095:Spermidine / Q000494:pharmacology
D018492:Dopamine Antagonists; D018691:Excitatory Amino Acid Antagonists; D010880:Piperidines; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; D006220:Haloperidol; C010739:ifenprodil; D013095:Spermidine