Developmental regulation of ionotropic glutamate receptors in central vestibular neurons in rats

Abstract

To investigate the role of ionotropic glutamate receptors (AMPARs and NMDARs) in the central vestibular neurons, whole-cell patch-clamp experiments were performed in spinal vestibular neurons of postnatal rats. The profiles of AMPARs and NMDARs were studied. From P1, glutamatergic transmission is primarily mediated by NMDARs. The relative contribution of AMPARs versus NMDARs at vestibular afferent synapses increased during the first two weeks of life. Using minimal stimulation procedures, NMDAR-only synapses were present only up to P5. In strontium-evoked miniatureEPSC recording, a significant increase in the quantal amplitude of AMPAR was observed from P5 to P7. These age-dependent increase of AMPARs towards the end of the first postnatal week coincides with the disappearance of NMDAR-only synapses. Taken together, our findings provide evidence on the developmental shift in AMPAR and NMDAR of glutamatergic synapses, contributing to functional maturation of central vestibular neurons in rats.