THE major input to neurons of the cochlear nucleus comes from the glutamatergic cells of the spiral ganglion. We have studied the effect of unilateral destruction of the inner ear, including the spiral ganglion, with two antibodies against different types of NMDA receptor subunits, NMDAR1 and NMDAR2A/B, in the cochlear nucleus of the rat. Following cochleotomy, a dramatic redistribution of the receptor subunits was observed from a mostly perikaryal to a predominantly dendritic localization. Moreover, distinct changes in the composition of NMDA receptor complexes occurred. These effects were interpreted as compensatory responses to the massive loss of presynaptic release of the transmitter glutamate.