NMDA AND NON-NMDA RECEPTORS ARE CO-LOCALIZED AT EXCITATORY SYNAPSES OF RAT HYPOGLOSSAL MOTONEURONS

We used whole-cell patch clamp recordings in a rat brainstem slice pre paration to characterize the properties of miniature excitatory postsy naptic currents (mEPSCs) in hypoglossal motoneurons. The distinct kine tic characteristics of N-methyl-D-aspartate (NMDA) and non-NMDA recept or-mediated synaptic responses allowed us to study dual component mEPS Cs mediated by the two receptor types. Using this approach, NMDA and n on-NMDA receptors were found to be co-localized at the same synaptic l ocations. In addition, some sites contain only NMDA receptors since a large proportion of mEPSCs were apparently mediated by NMDA receptors only. Furthermore, the amplitudes of pharmacologically isolated NMDA r eceptor-mediated mEPSCs were highly variable in individual cells and t heir decay kinetics were modulated by membrane potential. (C) 1997 Els evier Science Ireland Ltd.