Developmental profile of ionotropic glutamate receptors in spinal vestibular neurons of rats

Abstract

To address the role of glutamate receptors in developing vestibular system, Fos-immunohistochemistry was first used to chart the maturation time course of spinal vestibular (SpV) neurons in the coding of vertical head movements. Conscious rats (P4 to adult) were subjected to vertical linear acceleration. Functionally activated Fos-ir neurons were first found at P7. 80% of Fos/NMDA or Fos/AMPA double-labeled neurons were observed in all age. Whole-cell patch clamp also used to study the maturation profile of excitatory postsynaptic currents evoked by the vestibular nerves stimulation (eEPSCs). From P3 to P5, eEPSCs were dominated by NMDAR-mediated component, viz. 70% NMDARmediated versus 20% AMPAR-mediated eEPSCs. From P7 to P9, NMDAR-mediated component decreased to 50% while AMPARmediated component increased to 40%. Altogether our findings suggested that changes in AMPAR and NMDAR components in glutamatergic synapses play a crucial role in the maturation of SpV neurons during the first postnatal week.