Amino acid assay of vestibular nuclei 10 months after unilateral labyrinthectomy in squirrel monkeys.

Amino acids were assayed by HPLC in bilateral vestibular nuclei from normal squirrel monkeys (n = 3) and those 10-month post-unilateral labyrinthectomy (n = 4). Findings of vestibulo-spinal and vestibulo-oculomotor functions were identical for both groups. No left-right asymmetry of amino acids was found within either group, nor between groups with the exception of GABA: GABA was significantly reduced in the bilateral vestibular nuclei of the 10-month post-lesion animals. This may be indicative of a reduction of cerebello-vestibular inhibitory control which could be secondary to the reduction of excitatory inputs to the system.