Acetylcholinesterase activity changes in medial vestibular complex after hemilabyrinthectomy in the rat.

Acetylcholinesterase (AchE) activity was studied in pigmented rats 6 h to 1 y after hemilabyrinthectomy. A strong reduction of this activity was localized in the rostrocaudal extent of both the prepositus hypoglossi nucleus and the medial vestibular nucleus (that is, medial vestibular complex: VCm) ipsilateral to the lesion 6 h after the lesion. This deficit persisted within some areas dispersed throughout this complex 3 w and 1 y postoperatively. This result supports the hypothesis that the asymmetry of AchE activity in VCm could be necessary for vestibular compensation and provides an additional model for functional plasticity in the central nervous system.