Effect of MK801 on cFos-like protein expression in the medial vestibular nucleus at early stage of vestibular compensation in uvulonodullectomized rats.

The purpose of this study was to evaluate the effect of uvulonodullectomy (UNL) on the expression of cFos-like protein (FLP) in the medial vestibular nucleus (MVe) during vestibular compensation and effect of MK801, an N-methyl-D-aspartate (NMDA) antagonist, on FLP expression in the brain stem nuclei at 6 h after unilateral labyrinthectomy (ULX) with UNL in Sprague-Dawley rats. Immunohistochemical staining was performed to visualize FLP in the brain stem nuclei and FLP-positive cells were counted by image analyzer. Lesion-induced asymmetric expression of FLP in the bilateral MVe was observed and maintained up to for 72 h in the ULX group, and 120 h in the UNL + ULX group. Moreover, spatial pattern of FLP expression in the bilateral MVe exhibited the marked difference between the ULX and UNL + ULX groups. MK801 treatment 6 h after ULX showed significant increase in the number of FLP in contralateral MVe (cMVe) of the ULX group, but decrease in cMVe of the UNL + ULX group. These results suggest that the lesion of vestibulocerebellum delays the temporal recovery of FLP expression in MVe and the vestibulocerebellar NMDA receptors relate to FLP expression in MVe.