Interactions between phencyclidine and cholinergic excitation of hippocampal pyramidal neurons

The interaction between phencyclidine and acetylcholine-evoked responses of hippocampal pyramidal neurons was investigated in normal and catecholamine-depleted rats. Phencyclidine antagonized the acetylcholine-induced excitations in both preparations. However, in the majority of cases, this effect was observed only at doses of phencyclidine which also manifested nonspecific membrane stabilization. In contrast, phencyclidine-induced decreases in firing rate, which have been shown to be mediated by catecholamines, occurred at doses of phencyclidine which do not cause local anesthesia. Taken together, these data suggest that the catecholaminergically-mediated effects of phencyclidine may be more important in the hippocampus.