IMPAIRMENT OF SUCKLING RESPONSE, TRIGEMINAL NEURONAL PATTERN-FORMATION, AND HIPPOCAMPAL LTD IN NMDA RECEPTOR EPSILON-2 SUBUNIT MUTANT MICE

Multiple epsilon subunits are major determinants of the NMDA receptor channel diversity. Based on their functional properties in vitro and d istributions, we have proposed that the epsilon 1 and epsilon 2 subuni ts play a role in synaptic plasticity. To investigate the physiologica l significance of the NMDA receptor channel diversity, we generated mu tant mice defective in the epsilon 2 subunit. These mice showed no suc kling response and died shortly after birth but could survive by hand feeding. The mutation hindered the formation of the whisker-related ne uronal barrelette structure and the clustering of primary sensory affe rent terminals in the brain-stem trigeminal nucleus. In the hippocampu s of the mutant mice, synaptic NMDA responses and long-term depression were abolished. These results suggest that the epsilon 2 subunit play s an essential role in both neuronal pattern formation and synaptic pl asticity.