The role of N-methyl-D-aspartate receptor in the guinea pig inner ear after unilateral labyrinthectomy.

To investigate the role of the N-methyl-D-aspartate (NMDA) receptor in the vestibular periphery, vestibular compensation in the guinea pig was studied following chemical unilateral labyrinthectomy by osmotic pump administration of streptomycin sulfate (SM) with or without D-2-amino-5-phosphonovalerate (D-APV), one of the NMDA receptor antagonists. All animals administrated SM (SM group) or SM and D-APV (SM + D-APV group) showed spontaneous nystagmus and head tilt. The maximum degree of yaw head tilt in the SM + D-APV group was statistically smaller than that in the SM group. Moreover the time constant for head tilt in the SM + D-APV group was statistically shorter than that in the SM group. These results indicate that the NMDA receptor in the vestibular periphery influences vestibular compensation after unilateral labyrinthectomy.