Immunohistochemical Study On Vestibular Compensation Mechanism In Guinea Pigs

Abstract

γ-Aminobutylic acid (GABA) is involved in the pathway connecting the lateral vestibular nuclei (VL) and Purkinje cells. We investigated the change of GABA immunoreactivity during the course of vestibular compensation in 29 guinea pigs. The brain was obtained following vital perfusion 8-12 hours after unilateral labyrinthectomy in 10animals (group 1),40-48 hours thereafter in 9 (group 2), one week thereafter in 7 (group 3), and 6 months thereafter in 3 (group 4). PAP method with anti-GABA polyclonal antibody was employed; some specimens were observed with a light microscope, and the immunoreactivity of VL was measured using a microscopic photometer. Groups 1 and 2showed significantly higher GABA-like immunoreactivity of the VL on the labyrinthectomized side relative to that on the intact side, while groups 3 and 4 showed no significant difference in immunoreactivity of the VL on the two sides. The control group without the operation (n=3) and the sham operation group (n=2) also showed no difference in immunoreactivity. These findings suggest that GABA plays an important role as a neurotransmitter during vestibular compensation in guinea pigs.