AMPA and NMDA receptor properties in spinal vestibular neurons of developing rats

Abstract

Ionotropic glutamate receptors (AMPA and NMDA receptors) are important for signal transmission and synaptic plasticity in the vestibular system. However, contribution of the two types of ionotropic glutamate receptors to the coding of vestibular information during development remains unclear. Glutamatergic transmission in the spinal vestibular nucleus was studied in brainstem slices of P1–9 Sprague Dawley rats by whole-cell patchclamp approach. Analysis of miniature excitatory postsynaptic current (mEPSC) showed that both NMDA receptor- and AMPA receptor-mediated currents contributed equally to the mEPSC on or before P7. At P9, however, the AMPA component of the mEPSC became dominant ( 70%) as compared to the NMDA component. In response to electrical stimulation of the vestibular nerve, the evoked excitatory postsynaptic current (eEPSC) measured from brainstem slices was dominated by NMDA receptor-mediated current ( 70% of eEPSC) at P3/5. At P7/P9, the NMDA component decreased to 55% while the AMPA component increased to 45%. At P9, the linear I-V relationship of AMPA receptormediated eEPSC indicated the participation of GluR2 subunits in AMPA receptor. Our findings provide evidence that the functional maturation of spinal vestibular neurons may be related to the developmental profile of AMPA and NMDA receptors within glutamatergic synapses. Acknowledgement: Supported by HKRGC.