Effects of acute hypotension on expression of cFos-like protein in the vestibular nuclei of rats.

The expression and regional distribution of cFos protein, which is an oncogene product and metabolic marker of neural excitation, were investigated in the vestibular nuclear complex following acute hypotension in adult Sprague-Dawley rats. Intravenous administration of nitroprusside elicited a 10-50% reduction in mean blood pressure for 10 min. Unilateral or bilateral chemical labyrinthectomies were performed 14 days before the start of the experiment to eliminate afferent signals from the peripheral vestibular receptors in the inner ear.

Temporal changes of cFos-like protein expression in medial vestibular nuclei following arsanilate-induced unilateral labyrinthectomy in rats.

The compensation of spontaneous nystagmus and head deviation following chemical unilateral labyrinthectomy (UL) induced by arsanilate was delayed compared with surgical UL. Surgical UL produced two phases of significant asymmetry of cFos-like (cFL) protein expression between the bilateral medial vestibular nuclei, with more expression in the contralateral medial vestibular nuclei to the injured side than in the ipsilateral medial vestibular nuclei 2 h after UL; the pattern reversed after 6 h and expression disappeared after 72 h. Chemical UL produced three phases of asymmetric expression, with more cFL protein expression in the contralateral medial vestibular nuclei than in the ipsilateral medial vestibular nuclei 6 h after UL and a reversed pattern after 12 h.