Cobalt-sensitive and dihydropyridine-insensitive stimulation of dopamine release from tuberoinfundibular neurons by high extracellular concentrations of barium ions

M. Taglialatela, L. M T Canzoniero, S. Amoroso, A. Fatatis, G. F. Di Renzo, L. Annunziato

Research output: Contribution to journalArticle

Abstract

Recently, it has been demonstrated that Ca2+ entrance into the neuronal cytoplasm can occur upon the activation of 3 different types of specific voltage-dependent channels which can be characterized according to the following criteria: (1) voltage threshold for activation; (2) tendency to inactivation; (3) bivalent cation permeability; and (4) drug sensitivity. In this study we investigated, in tuberoinfundibular dopaminergic (TIDA) hypothalamic neurons, the biochemical and pharmacological properties of Ca2+ channels, by comparing the effects of high extracellular concentrations of Ba2+ and Ca2+ ions on [3H]dopamine (DA) release from TIDA neurons. The results obtained show that extracellular Ba2+ ion concentrations dose-dependently (10-20 mM) stimulated [3H]DA release from superfused TIDA neurons and that this effect was prevented by Co2+ ions (2 mM). In addition, superfusion of TIDA neurons with a concentration of Ca2+ ions equimolar to that by Ba2+ ions (20 mM) failed to modify [3H]DA release. The fact that tetraethylammonium (10 mM), a blocker of K+ currents in excitable cells, did not mimick the stimulatory action of Ba2+ ions on [3H]DA release, seems to exclude that the effect of Ba2+ ions was dependent on the inhibition of K+ channels in TIDA neurons. The ommission of Ca2+ ions from the extracellular medium did not prevent the stimulatory effect on [3H]DA release elicited by elevated concentrations of Ba2+ ions, but rather reinforced this effect. Finally, nitredipine (50 μM) did not modify the stimulatory effect of high extracellular Ba2+ ions on [3H]DA release from TIDA neurons.

Original languageEnglish
Pages (from-to)114-120
Number of pages7
JournalBrain Research
Volume488
Issue number1-2
DOIs
Publication statusPublished - May 29 1989

Fingerprint

Barium
Cobalt
Dopamine
Ions
Dopaminergic Neurons
Neurons
1,4-dihydropyridine
Dopamine Agents
Tetraethylammonium
Cations
Permeability
Cytoplasm
Pharmacology

Keywords

  • Barium
  • Calcium
  • Dihydropyridine
  • Dopamine release
  • Tuberoinfundibular dopaminergic neuron
  • Voltage-dependent Ca channel

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this

Cobalt-sensitive and dihydropyridine-insensitive stimulation of dopamine release from tuberoinfundibular neurons by high extracellular concentrations of barium ions. / Taglialatela, M.; Canzoniero, L. M T; Amoroso, S.; Fatatis, A.; Di Renzo, G. F.; Annunziato, L.

In: Brain Research, Vol. 488, No. 1-2, 29.05.1989, p. 114-120.

Research output: Contribution to journalArticle

Taglialatela, M. ; Canzoniero, L. M T ; Amoroso, S. ; Fatatis, A. ; Di Renzo, G. F. ; Annunziato, L. / Cobalt-sensitive and dihydropyridine-insensitive stimulation of dopamine release from tuberoinfundibular neurons by high extracellular concentrations of barium ions. In: Brain Research. 1989 ; Vol. 488, No. 1-2. pp. 114-120.
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abstract = "Recently, it has been demonstrated that Ca2+ entrance into the neuronal cytoplasm can occur upon the activation of 3 different types of specific voltage-dependent channels which can be characterized according to the following criteria: (1) voltage threshold for activation; (2) tendency to inactivation; (3) bivalent cation permeability; and (4) drug sensitivity. In this study we investigated, in tuberoinfundibular dopaminergic (TIDA) hypothalamic neurons, the biochemical and pharmacological properties of Ca2+ channels, by comparing the effects of high extracellular concentrations of Ba2+ and Ca2+ ions on [3H]dopamine (DA) release from TIDA neurons. The results obtained show that extracellular Ba2+ ion concentrations dose-dependently (10-20 mM) stimulated [3H]DA release from superfused TIDA neurons and that this effect was prevented by Co2+ ions (2 mM). In addition, superfusion of TIDA neurons with a concentration of Ca2+ ions equimolar to that by Ba2+ ions (20 mM) failed to modify [3H]DA release. The fact that tetraethylammonium (10 mM), a blocker of K+ currents in excitable cells, did not mimick the stimulatory action of Ba2+ ions on [3H]DA release, seems to exclude that the effect of Ba2+ ions was dependent on the inhibition of K+ channels in TIDA neurons. The ommission of Ca2+ ions from the extracellular medium did not prevent the stimulatory effect on [3H]DA release elicited by elevated concentrations of Ba2+ ions, but rather reinforced this effect. Finally, nitredipine (50 μM) did not modify the stimulatory effect of high extracellular Ba2+ ions on [3H]DA release from TIDA neurons.",
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T1 - Cobalt-sensitive and dihydropyridine-insensitive stimulation of dopamine release from tuberoinfundibular neurons by high extracellular concentrations of barium ions

AU - Taglialatela, M.

AU - Canzoniero, L. M T

AU - Amoroso, S.

AU - Fatatis, A.

AU - Di Renzo, G. F.

AU - Annunziato, L.

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