Effect of temperature and ionic environment on the specific binding of 3H(-)sulpiride to membranes from different rat brain regions

E. Carboni, M. Memo, G. L. Tanda, M. O. Carruba, P. F. Spano

Research output: Contribution to journalArticle

Abstract

Sulpiride is an antipsychotic drug endowed with the properties of a dopamine antagonist. The failure of sulpiride to inhibit neostriatal dopamine stimulated adenylate cyclase activity indicated that this drug is a selective D2 receptor antagonist. In this study we used a novel synthesized 2H(-)sulpiride with very high specific activity (72 Ci/mol) and characterized the temperature sensitivity of the binding sites labeled by this compound. Kinetic analysis of 3H(-)sulpiride binding in rat striatum showed unstable behavior when incubation was performed at 37 or 30°C. However when experiments were carried out at 15 or 10°C, binding reached a stable steady-state within 10 min. Scatchard analysis of binding isotherms obtained at 10°C showed a 5-fold increase in the maximum number of binding sites and a decrease in Kd values to one-third those obtained at 37°C. Pharmacological characterization of the binding sites labeled by 3H(-)sulpiride at 10°C showed a greater affinity for antagonists but not for agonists than 37°C. Under both experimental condition, 3H(-)sulpiride binding sites were Na+ and GTP-sensitive. The temperature sensitive binding phenomenon appeared to be area specific. 3H(-)sulpiride binding sites in tissues other than from striatum were influenced less or not at all by changes in incubation temperature.

Original languageEnglish
Pages (from-to)279-284
Number of pages6
JournalNeurochemistry International
Volume7
Issue number2
DOIs
Publication statusPublished - 1985

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ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Cellular and Molecular Neuroscience

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