Brainstem Fos expression following acute unilateral labyrinthectomy in the rat.

Detection of Fos protein expression with a polyclonal antibody was used to identify brainstem neurons responding to acute (24 h) effects of a unilateral sodium arsanilate chemical labyrinthectomy in Long-Evans rats. Asymmetrical expression was apparent in the medial and inferior vestibular nuclei, the prepositus hypoglossi, the dorsolateral central gray, and the inferior olivary beta subnucleus. These data suggest different distributions of neural activation compared with previous electrophysiological and 2-deoxyglucose results. In addition, there was some Fos expression bilaterally in the olivary dorsomedial cell column, interstitial nucleus of Cajal and the Darkschewitsch nucleus. These results support the concept of multiple systems participating in vestibular compensation and further define some specific nuclei involved in the acute stage.