Ethanol inhibits vestibular and caloric nystagmus without affecting optokinetic nystagmus in rabbits.

Effects of ethanol on optokinetic, vestibular and caloric nystagmus were investigated in pigmented rabbits to determine whether or not it affects a specific site involved in the induction of various nystagmus. Optokinetic nystagmus was produced by rotation of the drum with vertical stripes at an angular velocity of 0.85 degrees/sec. Vestibular nystagmus was induced by horizontal rotation at an angular velocity of 30 degrees/sec and caloric nystagmus by infusion of cold water into the external meatus. Cumulative injection of ethanol into the auricular vein to doses of 0.1, 0.2, 0.4 and 0.8 g/kg inhibited both vestibular and caloric nystagmus dose-dependently, but did not affect the optokinetic nystagmus. These results suggest that relatively low doses of ethanol mainly act on the peripheral vestibular organ and impair the vestibular function without affecting the optokinetic system.