Early chronic blockade of NR2B subunits and transient activation of NMDA receptors modulate LTP in mouse auditory cortex

Brain Res. 2006 Feb 16;1073-1074:131-8. doi: 10.1016/j.brainres.2005.12.077. Epub 2006 Feb 2.

Abstract

In the auditory cortex, the properties of NMDA receptors depend primarily on the ratio of NR2A and NR2B subunits. NR2B subunit expression is high at the beginning of critical period and lower in adulthood. Because NMDA receptors are crucial in triggering long-term potentiation (LTP) and long-term depression, developmental or experience-dependent modification of NMDAR subunit composition is likely to influence synaptic plasticity. To examine how NMDA subunit change during postnatal development affect the adult synaptic plasticity, we employed chronic ifenprodil blockade of NR2B subunits and analyzed evoked field potentials in adult C57BL/6 mice auditory cortex (AC). We found that chronic loss of NR2B activity led to a decline in LTP magnitude in the AC of adult mice. Adding NMDA to the artificial cerebrospinal fluid (ACSF) in blocked mice had the opposite effect, producing LTP magnitudes at or exceeding those found in treated or untreated animals. These results suggest that, even in adulthood when NR2B expression is downregulated, these receptor subunits play an important role in experience-dependent plasticity of mouse auditory cortex. Blockade from P60 did not result in any decrease of LTP amplitude, suggesting that chronic block in postnatal period may permanently affect cortical circuits so that they cannot produce significant LTP in adulthood.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Auditory Cortex / physiology*
  • Auditory Cortex / radiation effects
  • Drug Administration Schedule
  • Drug Interactions
  • Electric Stimulation / methods
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • In Vitro Techniques
  • Infusion Pumps, Implantable
  • Long-Term Potentiation / drug effects
  • Long-Term Potentiation / physiology*
  • Long-Term Potentiation / radiation effects
  • Long-Term Synaptic Depression / drug effects
  • Long-Term Synaptic Depression / physiology
  • Long-Term Synaptic Depression / radiation effects
  • Mice
  • Mice, Inbred C57BL
  • N-Methylaspartate / pharmacology
  • Piperidines / administration & dosage
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / physiology*
  • Time Factors

Substances

  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • NR2B NMDA receptor
  • Piperidines
  • Receptors, N-Methyl-D-Aspartate
  • N-Methylaspartate
  • ifenprodil