Effects of Deafferented Sensory Inputs on c-fos mRNA Expression in Medial Vestibular Nucleus of Rats Following Unilateral Labyrinthectomy

Suh, Han Kyu; Lee, Eun Soo; Seo, Kyu Hwan; Chae, Sung Won; Hwang, Soon Jae; Cha, Heung Eog

Abstract

BACKGROUND AND OBJECTIVES: Fos is a protein product of proto-oncogene c-fos, which is induced by various kinds of stimulations such as noxious, physiologic and electrical stimulations. In the vestibular system, there have been several evidences that c-fos was expressed in the brainstem vestibular nuclei during vestibular compensation following unilateral labyrinthectomy (ULX). In this study, the author evaluated the effect of deafferented sensory inputs on the c-fos mRNA expression in the medial vestibular nucleus of unilaterally labyrinthectomized rats.
MATERIALS AND METHODS
Animals in the experimental group underwent tarsorraphy and cervical dorsal ganglionectomy to deprive them of visual and proprioceptive sensory inputs immediately after ULX, whereas the experimental group II did not receive any procedure after ULX. Expression of c-fos mRNA was demonstrated by in situ hybridization technique. All animals were sacrificed at 1, 3, 6, 9, 24, 48 hours after ULX and frozen sectioned tissues of brainstem were used in situ hybridization.
RESULTS
Three hours after ULX, the expression of c- fos mRNA was increased in the dorsal portion of medial vestibular nucleus (dMVN) in both groups and after 6 hours of ULX, it was markedly reduced. In group I (deafferented), however, asymmetric expression was observed in 24 hours after the operation. In group II, the increased expression of c-fos mRNA in the ipsilateral dMVN continued until 9 hours after the operation and thereafter, the asymmetry of c-fos mRNA expressions between the ipsilateral and contralateral dMVN was decreased.
CONCLUSION
These findings suggest that vision and proprioception influenced the expression of c-fos mRNA in the brainstem medial vestibular nucleus after ULX and corrected the asymmetric expression between the healthy and lesioned nuclei earlier than the deafferented group.