A voltage-clamp analysis of NMDA-induced responses on dopaminergic neurons of the rat subtantia nigra zona compacta and ventral tegmental area

Nicola B. Mercuri, Francesca Stratta, Paolo Calabresi, Giorgio Bernardi

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of NMDA-receptor activation on dopaminergic neurons of the rat substantia nigra zona compacta and ventral tegmental area were studied by using in vitro intracellular electrophysiological recordings (current and voltage-clamp). NMDA depolarized the membrane and increased the firing activity. A voltage-dependent inward current and a reduction of the apparent input conductance were observed in voltage-clamp experiments. Interestingly, the peak amplitude of the inward current occurred at approximately - 60 mV. The NMDA-induced responses were reduced by the application of dl-2-amino-5-phophonovaleric acid (APV). The NMDA-induced current was unaffected by potassium channel blockers, was present in low-sodium solutions or in solutions treated with TTX; but was reduced or blocked in low-calcium solutions containing cobalt. In addition, no reduction of the apparent input conductance was observed either in the solutions without magnesium or in those with low-sodium. Our data indicate that the activation of NMDA receptors produces a powerful excitatory stimulus on the dopaminergic neurons of the ventral mesencephalon and this may be primarily the result of a voltage-dependent influx of calcium ions. The degeneration of the dopaminergic cells after application of neurotoxins may be explained by their peculiar response to NMDA.

Original languageEnglish
Pages (from-to)51-56
Number of pages6
JournalBrain Research
Volume593
Issue number1
DOIs
Publication statusPublished - Oct 9 1992

Keywords

  • Excitatory amino acid receptor
  • Intracellular recording
  • Slice
  • Ventral mesencephalon

ASJC Scopus subject areas

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

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