Binding of [3H]SCH23390 in Rat Brain

Regional Distribution and Effects of Assay Conditions and GTP Suggest Interactions at a D1‐Like Dopamine Receptor

David W. Schulz, Edward J. Stanford, Stephen W. Wyrick, Richard Mailman

Research output: Contribution to journalArticle

109 Citations (Scopus)

Abstract

Abstract: The compound [9‐3H]SCH23390 [R‐(+)‐8‐chloro‐2,3,4,5‐tetrahydro‐3‐methyl‐5‐phenyl‐1H‐3‐benzazepine‐7‐ol] was synthesized, and the binding of this purportedly selective antagonist of D1 3,4‐dihydroxyphenylethylamine (dopamine) receptors was characterized. The regional distribution of high‐affinity, specific [3H]SCH23390 binding sites in the rat brain correlated well with levels of endogenous dopamine. Receptor densities were greatest in corpus striatum, nucleus accumbens, and olfactory tubercle; intermediate levels were found in several limbic and cortical areas, whereas few sites were detectable in cerebellum, brainstem, and olfactory bulb. Specific binding in caudate‐putamen was found to be both temperature‐ and pH‐dependent, with optima at 25–30°C and pH 7.8–8.0. Scatchard or Woolf analyses of binding in caudate‐putamen suggest that most of the sites are either of a single class or of classes with similar characteristics (KD= 0.7 ± 0.1 nM; Bmax= 347 ± 35 fmol/mg of protein). Both dopamine and cis‐flupenthixol altered the slope but not the intercept of lines generated by Scatchard analysis, suggesting a competitive mode of inhibition of [3H]SCH23390 binding. Competition for binding by dopamine or the D1 agonist SKF38393 was inhibited by guanine nucleotides, whereas GTP had little effect on the competition for binding by the antagonist cis‐flupenthixol. The competition for [3H]SCH23390 binding sites by dopamine was much more sensitive to GTP than was competition for [3H]spiperone binding. These data support the hypotheses that [3H]SCH23390 binds to recognition sites that differ from those previously described using other radiolabeled dopamine antagonists and that these sites have the characteristics expected of dopamine receptors.

Original languageEnglish (US)
Pages (from-to)1601-1611
Number of pages11
JournalJournal of neurochemistry
Volume45
Issue number5
DOIs
StatePublished - Jan 1 1985

Fingerprint

Dopamine Receptors
Guanosine Triphosphate
Rats
Assays
Brain
Binding Sites
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine
Corpus Striatum
Spiperone
Guanine Nucleotides
Olfactory Bulb
Nucleus Accumbens
Cerebellum
Brain Stem
SCH 23390
Temperature
Proteins

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

@article{7c09b84ee43f4d3b9d83ad4d5e5f5edb,
title = "Binding of [3H]SCH23390 in Rat Brain: Regional Distribution and Effects of Assay Conditions and GTP Suggest Interactions at a D1‐Like Dopamine Receptor",
abstract = "Abstract: The compound [9‐3H]SCH23390 [R‐(+)‐8‐chloro‐2,3,4,5‐tetrahydro‐3‐methyl‐5‐phenyl‐1H‐3‐benzazepine‐7‐ol] was synthesized, and the binding of this purportedly selective antagonist of D1 3,4‐dihydroxyphenylethylamine (dopamine) receptors was characterized. The regional distribution of high‐affinity, specific [3H]SCH23390 binding sites in the rat brain correlated well with levels of endogenous dopamine. Receptor densities were greatest in corpus striatum, nucleus accumbens, and olfactory tubercle; intermediate levels were found in several limbic and cortical areas, whereas few sites were detectable in cerebellum, brainstem, and olfactory bulb. Specific binding in caudate‐putamen was found to be both temperature‐ and pH‐dependent, with optima at 25–30°C and pH 7.8–8.0. Scatchard or Woolf analyses of binding in caudate‐putamen suggest that most of the sites are either of a single class or of classes with similar characteristics (KD= 0.7 ± 0.1 nM; Bmax= 347 ± 35 fmol/mg of protein). Both dopamine and cis‐flupenthixol altered the slope but not the intercept of lines generated by Scatchard analysis, suggesting a competitive mode of inhibition of [3H]SCH23390 binding. Competition for binding by dopamine or the D1 agonist SKF38393 was inhibited by guanine nucleotides, whereas GTP had little effect on the competition for binding by the antagonist cis‐flupenthixol. The competition for [3H]SCH23390 binding sites by dopamine was much more sensitive to GTP than was competition for [3H]spiperone binding. These data support the hypotheses that [3H]SCH23390 binds to recognition sites that differ from those previously described using other radiolabeled dopamine antagonists and that these sites have the characteristics expected of dopamine receptors.",
author = "Schulz, {David W.} and Stanford, {Edward J.} and Wyrick, {Stephen W.} and Richard Mailman",
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Binding of [3H]SCH23390 in Rat Brain : Regional Distribution and Effects of Assay Conditions and GTP Suggest Interactions at a D1‐Like Dopamine Receptor. / Schulz, David W.; Stanford, Edward J.; Wyrick, Stephen W.; Mailman, Richard.

In: Journal of neurochemistry, Vol. 45, No. 5, 01.01.1985, p. 1601-1611.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Binding of [3H]SCH23390 in Rat Brain

T2 - Regional Distribution and Effects of Assay Conditions and GTP Suggest Interactions at a D1‐Like Dopamine Receptor

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N2 - Abstract: The compound [9‐3H]SCH23390 [R‐(+)‐8‐chloro‐2,3,4,5‐tetrahydro‐3‐methyl‐5‐phenyl‐1H‐3‐benzazepine‐7‐ol] was synthesized, and the binding of this purportedly selective antagonist of D1 3,4‐dihydroxyphenylethylamine (dopamine) receptors was characterized. The regional distribution of high‐affinity, specific [3H]SCH23390 binding sites in the rat brain correlated well with levels of endogenous dopamine. Receptor densities were greatest in corpus striatum, nucleus accumbens, and olfactory tubercle; intermediate levels were found in several limbic and cortical areas, whereas few sites were detectable in cerebellum, brainstem, and olfactory bulb. Specific binding in caudate‐putamen was found to be both temperature‐ and pH‐dependent, with optima at 25–30°C and pH 7.8–8.0. Scatchard or Woolf analyses of binding in caudate‐putamen suggest that most of the sites are either of a single class or of classes with similar characteristics (KD= 0.7 ± 0.1 nM; Bmax= 347 ± 35 fmol/mg of protein). Both dopamine and cis‐flupenthixol altered the slope but not the intercept of lines generated by Scatchard analysis, suggesting a competitive mode of inhibition of [3H]SCH23390 binding. Competition for binding by dopamine or the D1 agonist SKF38393 was inhibited by guanine nucleotides, whereas GTP had little effect on the competition for binding by the antagonist cis‐flupenthixol. The competition for [3H]SCH23390 binding sites by dopamine was much more sensitive to GTP than was competition for [3H]spiperone binding. These data support the hypotheses that [3H]SCH23390 binds to recognition sites that differ from those previously described using other radiolabeled dopamine antagonists and that these sites have the characteristics expected of dopamine receptors.

AB - Abstract: The compound [9‐3H]SCH23390 [R‐(+)‐8‐chloro‐2,3,4,5‐tetrahydro‐3‐methyl‐5‐phenyl‐1H‐3‐benzazepine‐7‐ol] was synthesized, and the binding of this purportedly selective antagonist of D1 3,4‐dihydroxyphenylethylamine (dopamine) receptors was characterized. The regional distribution of high‐affinity, specific [3H]SCH23390 binding sites in the rat brain correlated well with levels of endogenous dopamine. Receptor densities were greatest in corpus striatum, nucleus accumbens, and olfactory tubercle; intermediate levels were found in several limbic and cortical areas, whereas few sites were detectable in cerebellum, brainstem, and olfactory bulb. Specific binding in caudate‐putamen was found to be both temperature‐ and pH‐dependent, with optima at 25–30°C and pH 7.8–8.0. Scatchard or Woolf analyses of binding in caudate‐putamen suggest that most of the sites are either of a single class or of classes with similar characteristics (KD= 0.7 ± 0.1 nM; Bmax= 347 ± 35 fmol/mg of protein). Both dopamine and cis‐flupenthixol altered the slope but not the intercept of lines generated by Scatchard analysis, suggesting a competitive mode of inhibition of [3H]SCH23390 binding. Competition for binding by dopamine or the D1 agonist SKF38393 was inhibited by guanine nucleotides, whereas GTP had little effect on the competition for binding by the antagonist cis‐flupenthixol. The competition for [3H]SCH23390 binding sites by dopamine was much more sensitive to GTP than was competition for [3H]spiperone binding. These data support the hypotheses that [3H]SCH23390 binds to recognition sites that differ from those previously described using other radiolabeled dopamine antagonists and that these sites have the characteristics expected of dopamine receptors.

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