I. NGD 94–1: Identification of a Novel, High-Affinity Antagonist at the Human Dopamine D4 Receptor

  1. John F. Tallman,
  2. Renee J. Primus,
  3. Robbin Brodbeck,
  4. Linda Cornfield1,
  5. Robin Meade,
  6. Kristine Woodruff2,
  7. Phillip Ross3,
  8. Andrew Thurkauf and
  9. Dorothy W. Gallager
  1. Neurogen Corporation, Branford, Connecticut

    Abstract

    NGD 94–1 was evaluated for selectivity and in vitrofunctional activity at the recombinant human D4.2receptor stably expressed in Chinese hamster ovary cells. NGD 94–1 showed high affinity for the cloned human D4.2receptor (Ki = 3.6 ± 0.6 nM) and had greater than 600-fold selectivity for the D4.2receptor subtype compared with a wide variety of monoamine or other neurotransmitter receptor or modulatory sites except for 5-HT1A and 5-HT3 receptors, in which NGD 94–1 was approximately 50- and 200-fold selective, respectively, for the D4.2 receptor. In measures of in vitro functional activity, NGD 94–1 showed an antagonist profile at the cloned human D4.2receptor subtype. NGD 94–1 completely reversed the decrease in forskolin-stimulated cAMP levels produced by the dopamine receptor full agonist quinpirole. Furthermore, NGD 94–1 produced a complete reversal of GTPγ35S binding induced by quinpirole, but was unable on its own to affect GTPγ35S binding. These data suggest that NGD 94–1 functions as an antagonist rather than a full or partial agonist at the human D4.2 receptor. In addition, NGD 94–1 binding affinity at the D4.2 receptor subtype was unaffected by G-protein activation by GTP, consistent with the binding affinity seen for other antagonists at the D4receptor. The binding of tritiated NGD 94–1 was saturable and of high affinity at cloned human D4.2 receptors. Furthermore, the binding of [3H]NGD 94–1 to cloned human D4.2 receptors expressed in Chinese hamster ovary cells displayed a pharmacological profile similar to that observed with the nonselective dopamine receptor ligand [3H]YM 09151–2. Saturation and pharmacological analyses of [3H]NGD 94–1 binding at cloned human D4.2, D4.4 and D4.7 receptor variants showed no difference between the three variants. NGD 94–1 is a novel, high-affinity, D4 receptor-selective antagonist. The clinical use of this subtype-specific compound should permit direct evaluation of the role of D4 receptors in psychiatric disorders.

    Footnotes

    • Send reprint requests to: Dr. John F. Tallman, Neurogen Corporation, 35 N.E. Industrial Rd., Branford, CT 06405.

    • ↵1 Current address: Bayer Corporation Pharmaceutical Division, West Haven, CT.

    • ↵2 Current address: Bristol-Meyers Squibb, Wallingford, CT.

    • ↵3 Current address: Pfizer Incorporated, Groton, CT.

    • Abbreviations:
      NGD 94–1
      2-phenyl-4(5)-[4-(2-pyrimidinyl)-piperazin-1-yl)-methyl]-imidazole dimaleate
      BSA
      bovine serum albumin
      CHO
      Chinese hamster ovary
      cAMP
      cyclic adenosine monophosphate
      DMEM
      Dulbecco’s modified eagle’s medium
      EGTA
      ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid
      FBS
      fetal bovine serum
      HEPES
      N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid
      IBMX
      3-isobutyl-1-methylxanthine
      NMDA
      N-methyl-d-aspartate
      PCR
      polymerase chain reaction
      PBS
      phosphate-buffered saline
      RIA
      radioimmunoassay
      • Received October 18, 1996.
      • Accepted April 8, 1997.
    « Previous | Next Article »Table of Contents

    This Article

    1. JPET August 1, 1997 vol. 282 no. 2 1011-1019
    1. » Abstract
    2. Full Text
    3. Full Text (PDF)

    Classifications

    Responses

    1. Submit a response
    2. No responses published

    Current Issue

    1. November 2009, 331 (2)
    1. Current Issue
    1. Alert me to new issues of JPET