The influence of diazepam on the activity of secondary vestibular neurons in the rabbit.

We have studied the influence of intravenously administered diazepam on the activity of single secondary vestibular neurons in unanesthetized, paralyzed rabbits evoked by sinusoidal angular accelerations about the vertical and longitudinal axes. Intravenous injections of diazepam (20-100 micrograms/kg) caused a decreased sensitivity of all secondary vestibular neurons which were tested. The reduction in sensitivity was sometimes preceded by a transient increase in excitability which lasted 10-40 sec. The duration of the decreased sensitivity to vestibular stimulation following intravenous injections of diazepam was dose-dependent, lasting 15-60 min. These data suggest that the diazepam-induced reduction of vestibuloocular reflexes is caused, at least in part, by the depressant action of diazepam upon secondary vestibular neurons.