Expression of NMDA, AMPA and GABA(A) receptor subunit mRNAs in the rat auditory brainstem. II. Influence of intracochlear electrical stimulation

We investigated the effects of intracochlear electrical stimulation (ICES) on auditory pathways of neonatal rat deafened by daily amikacin injections. Expression of mRNAs encoding ionotropic glutamate receptor subunits such a s alpha -amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and N-methyl-D-asparta te (NMDA), and gamma -aminobutyric acid type A (GABA(A)) receptor subunits was assessed hi in situ hybridization in the dorsal (DCM) and the ventral c ochlear nucleus (VCN) and in the central nucleus of the inferior colliculus (CNIC). After 15 days of daily unilateral ICES, the expressions of NR1, NR 2b and NR2c subunits of NMDA receptor, that of GluRA. B, C, D flop isoforms of AMPA receptor. and that of some GABAA subunits (alpha1, beta1, gamma1, gamma2) were increased bilaterally in the DCN, VCN and the CNIC. These chan ges last over a week after stimulation for only NR1 and NR2c. These modific ations might be I elated to long lasting synaptic plasticity of brainstem a uditory pathways. As far as analogy to deaf children can be made, early ele ctrical stimulation might be of interest to maintain neuronal networks. (C) 2000 Elsevier Science B.V. All rights reserved.