NOVEL MOLECULAR SITE FOR ANTIDOPAMINERGIC EFFECTS

Project: Research project

Description

Based on the general hypothesis that microheterogeneity of dopamine
receptors prevents prediction of functional effects simply on the basis of
D1 or D2 biochemical characteristics, we propose to study a high affinity,
specific D1-like recognition site, not previously characterized, that can
mediate profound antidopaminergic behavioral effects. To accomplish this
objective, [3H]-SCH23390 has been synthesized, and its chemical and
biological identity to the authentic SCH23390 verified. We have
demonstrated that there is a persistence of SCH23390 in brain, and
prolonged behavioral and biochemical effects, hours after the blood
concentration of drug is undetectable, directly opposite to our data with
other neuroleptics. Thus, the metabolism of SCH23390 and its time course
of distribution (especially in discrete brain regions) will be thoroughly
studied. Using classical radioligand methods, the interactions of
[3H]-SCH23390 with its binding sites in crude brain membrane fractions will
be characterized, utilizing both in vitro and in vivo binding methods, and
compared to other ligands which are believed to bind to sites usually
considered to be dopamine receptors. The properties of the iodine analog
of SCH23390 will be evaluated, and if similar to SCH23390, [125I]-SCH23390
will be used as a very high specific activity tool for receptor studies.
Autoradiographic techniques will be used to map the distribution of
[125I]-SCH23390 or [3H]-SCH23390 binding sites in brain after
administration of the radioligands in vivo, or treatment of brain slices in
vitro. Since we have shown that SCH23390 will bind tenaciously to its
physiologically important receptor(s), the subcellular localization of the
radioactive drug in cellular fractions prepared from brain regions of rats
treated in vivo with [125I]-SCH23390 or [3H]-SCH23390 will be determined.
The effects of lesioning dopamine pathways or chronic treatment with
antipsychotics on SCH23390 recognition sites will also be examined. If
these studies are successful, solubilization and purification of the
SCH23390 binding sites will be attempted, relying heavily on affinity
chromatography to take advantage of the apparent high affinity of these
binding sites.
StatusFinished
Effective start/end date4/1/851/31/04

Funding

  • National Institutes of Health
  • National Institutes of Health: $254,755.00
  • National Institutes of Health: $273,324.00
  • National Institutes of Health
  • National Institutes of Health: $206,385.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $302,061.00
  • National Institutes of Health: $19,373.00
  • National Institutes of Health: $251,621.00
  • National Institutes of Health: $199,160.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

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Ligands
Adenylyl Cyclases
Dopamine D1 Receptors
Pharmaceutical Preparations
Drug Design
Molecular Computers
Dopamine Antagonists
Dopamine Agonists
Post Translational Protein Processing
Binding Sites
Dopamine
GTP-Binding Proteins
Pharmacology
Dopamine Receptors
Research
Brain
Chromatography
Proteins
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine
Neurotransmitter Receptor