Lead inhibition of N-methyl-D-aspartate receptors containing NR2A, NR2C and NR2D subunits

J Pharmacol Exp Ther. 1997 Sep;282(3):1458-64.

Abstract

The potency of Pb2+ inhibition of glutamate-activated currents mediated by N-methyl-D-aspartate (NMDA) receptors was dependent on the subunits composing the receptors when functionally expressed in Xenopus laevis oocytes. Pb2+ reduced the amplitudes of glutamate-activated currents and shifted the agonist EC50 values of NMDA receptors consisting of different subunit compositions. The IC50 values for Pb2+ ranged from 1.52 to 8.19 microM, with a rank order of potency of NR1b-2A > NR1b-2C > NR1b-2D > NR1b-2AC. For NR1b-2AC NMDA receptors, the IC50 value was dependent on the agonist concentration; at saturating agonist concentrations (300 microM), the IC50 value was 8.19 microM, whereas at 3 microM glutamate, the IC50 value was 3.39 microM. Pb2+ was a noncompetitive inhibitor of NR1b-2A, NR1b-2C and NR1b-2D NMDA receptors. At low concentrations (<1 microM) Pb2+ potentiated NR1b-2AC NMDA receptors. These data provide further evidence to support the hypothesis that the actions of Pb2+ on NMDA receptors are determined by the receptor subunit composition.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Dose-Response Relationship, Drug
  • Female
  • Glutamic Acid / pharmacology
  • Lead / pharmacology*
  • Rats
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors*
  • Receptors, N-Methyl-D-Aspartate / chemistry
  • Xenopus laevis

Substances

  • Receptors, N-Methyl-D-Aspartate
  • Lead
  • Glutamic Acid