Evidence for the existence of two distinct dopamine D-2 receptors in presynaptic nerve terminals from rat corpus striatum

M. Pizzi, A. Valerio, M. O. Carruba, M. Benarese, S. Espositi, M. Memo, P. F. Spano

Research output: Contribution to journalArticle

Abstract

1 Radioactive rubidium (86Rb+) efflux was used to measure potassium (K+) permeability in a study designed to assess both the presence and the sensitivity to ions and drugs of the K+ channels in the presynaptic nerve terminals of rat striatum. This method allowed differential measurement of the activity of two distinct components of 86Rb+ efflux, component V (sensitive to voltage and Ca2+-independent) and component C (Ca2+-activated). 2 A series of dopamine D-2 receptor agonists, including quinpirole, bromocriptine and Ru 24213, appeared to affect both components of 86Rb+ efflux. The EC50 values of quinpirole, bromocriptine and Ru 24213 for activating component V of 86Rb+ efflux were 5 pM, 15 pM and 40 pM, respectively. These drugs also stimulated component C of 86Rb+ efflux in the same order, but with lower, potency. 3 The dopaminergic D-2 agonist BHT 920 discriminated between the two components being active on component V (EC50 = 200 pM) and inactive on component C (up to 1 - μM). 4 Activation of voltage-sensitive 86Rb+ efflux by various dopamine D-2 receptor agonists, including BHT 920, were antagonized by 0.1 μM (-)-sulpiride but not by 0.1 μM yohimbine. 5 Lesioning of the nigro-striatal pathway by injection of 6-hydroxydopamine in the substantia nigra caused a reduction of about 60% of the BHT 920-stimulated, voltage-sensitive, Ca2+ independent 86Rb+ efflux (component V). 6 These data indicate that striatal presynaptic nerve terminals contain two distinct dopamine D-2 receptors which can be differentiated both functionally and pharmacologically.

Original languageEnglish
Pages (from-to)83-89
Number of pages7
JournalMolecular Neuropharmacology
Volume3
Issue number2
Publication statusPublished - 1993

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Corpus Striatum
Presynaptic Terminals
Quinpirole
Dopamine
Bromocriptine
Rubidium
Sulpiride
Yohimbine
Oxidopamine
Substantia Nigra
Pharmaceutical Preparations
Permeability
Potassium
Ions
Injections
talipexole

ASJC Scopus subject areas

  • Pharmacology
  • Neuroscience(all)

Cite this

Pizzi, M., Valerio, A., Carruba, M. O., Benarese, M., Espositi, S., Memo, M., & Spano, P. F. (1993). Evidence for the existence of two distinct dopamine D-2 receptors in presynaptic nerve terminals from rat corpus striatum. Molecular Neuropharmacology, 3(2), 83-89.

Evidence for the existence of two distinct dopamine D-2 receptors in presynaptic nerve terminals from rat corpus striatum. / Pizzi, M.; Valerio, A.; Carruba, M. O.; Benarese, M.; Espositi, S.; Memo, M.; Spano, P. F.

In: Molecular Neuropharmacology, Vol. 3, No. 2, 1993, p. 83-89.

Research output: Contribution to journalArticle

Pizzi, M, Valerio, A, Carruba, MO, Benarese, M, Espositi, S, Memo, M & Spano, PF 1993, 'Evidence for the existence of two distinct dopamine D-2 receptors in presynaptic nerve terminals from rat corpus striatum', Molecular Neuropharmacology, vol. 3, no. 2, pp. 83-89.
Pizzi, M. ; Valerio, A. ; Carruba, M. O. ; Benarese, M. ; Espositi, S. ; Memo, M. ; Spano, P. F. / Evidence for the existence of two distinct dopamine D-2 receptors in presynaptic nerve terminals from rat corpus striatum. In: Molecular Neuropharmacology. 1993 ; Vol. 3, No. 2. pp. 83-89.
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