Elsevier

Neuroscience

Volume 69, Issue 4, December 1995, Pages 1057-1065
Neuroscience

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

https://doi.org/10.1016/0306-4522(95)00337-IGet rights and content

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.

Reference (35)

  • CarmignotoG. et al.

    Activity-dependent decrease in NMDA receptor responses during development of the visual cortex

    Science

    (1992)
  • CherubiniE. et al.

    GABA: an excitatory transmitter in early postnatal life

    Trends Neurosci.

    (1991)
  • ColquhounD. et al.

    Fitting and statistical analysis of single-channel records

  • Constantine-PatonM. et al.

    Pattern activity, synaptic convergence and the NMDA receptor in developing visual pathways

    A. Rev. Neurosci.

    (1990)
  • FarrantM. et al.

    NMDA-receptor channel diversity in the developing cerebellum

    Nature

    (1994)
  • GibbA.J. et al.

    Glytamate activation of a single NMDA receptor-channel produces a cluster of channel openings

  • HamillO.P. et al.

    Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches

    Pflügers Arch.

    (1981)
  • Cited by (0)

    *

    Present address: Kazan Medical Institute, Department of Physiology, 49, Butlerov str., Kazan 420012, Russia.

    Present address: Centro Ricerca Sperimentale, Instituto Regina Elena via Delle Messi D'Oro, 156, Rome, Italy.

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