Activation of lateral vestibular nucleus neurons by iontophoretically applied phencyclidine

Microiontophoretic studies were performed to elucidate the effects of phencyclidine (PCP) on neuronal activity in the lateral vestibular nucleus (LVN) of cats anesthetized with alpha-chloralose. Spikes elicited in the monosynaptic LVN neurons by vestibular nerve stimulation were not affected by iontophoretic application of PCP up to 100 nA, but they were blocked by atropine (30-50 nA). A dose-dependent increase in spontaneous firing during application of PCP was obtained in 11 of 15 monosynaptic neurons, in all of which firing was increased by iontophoretically applied acetylcholine (ACh). Simultaneous application of atropine completely inhibited the PCP- and ACh-induced increase in the firing without affecting the glutamate-induced firing. These results indicate that PCP acts on the LVN monosynaptic neurons receiving input from the vestibular nerve in a similar manner to ACh.