Kinetics and Mg2+ block of N-methyl- d-aspartate receptor channels during postnatal development of hippocampal CA3 pyramidal neurons

R. Khazipov, D. Ragozzino, P. Bregestovski

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Abstract

Voltage-dependent magnesium block of N-methyl- d-aspartate-activated channels, and the N-methyl- d-aspartate component of excitatory synaptic currents were studied in CA3 pyramidal neurons of hippocampal slices from immature (postnatal day 3-8) and adult (postnatal day 25-60) rats. In all neurons studied the kinetics of single-channel openings in cell-attached and inside-out configurations was strongly modulated by extracellular Mg2+, in a voltage-dependent manner. No age-dependent difference in the Mg2+-sensitivity of N-methyl- d-aspartate channels was observed. At physiological concentrations of external Mg2+ (1.3 mM), N-methyl- d-aspartate components of excitatory synaptic currents measured from immature and adult rats displayed a similar voltage-dependence. In immature neurons (postnatal day 3-6), the N-methyl- d-aspartate component of excitatory postsynaptic currents decay time-course was a single-exponential with an average time-constant of about 300 ms. In neurons from older animals the decay was described by a double-exponential function with both a fast component (τf, 54-130 ms) and a slow component (τs, 275-400 ms). With age, the contribution of the fast component increased and the decay time-course of the N-methyl- d-aspartate component of excitatory postsynaptic currents accelerated. It is concluded that the Mg2+ block of N-methyl- d-aspartate channels in CA3 pyramidal neurons does not change with development, but the kinetic properties of N-methyl- d-aspartate receptor channels are developmentally regulated.

Original languageEnglish
Pages (from-to)1057-1065
Number of pages9
JournalNeuroscience
Volume69
Issue number4
DOIs
Publication statusPublished - 1995

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Keywords

  • channels
  • glutamate receptor
  • hippocampal slices
  • patch-clamp

ASJC Scopus subject areas

  • Neuroscience(all)

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