Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to be neuroprotective in animal models of different brain pathologies, including focal and global cerebral ischemia. The application of glutaminergic excitotoxin kainic acid (KA), similar to ischemic events, may lead to neurodegeneration. In the present article, we investigated the effects of microiontophoretic application of PACAP on the excitatory effects of KA. During recording-maintained spontaneous activity of single neurons, we microiontophoretized KA, which was followed by the application of PACAP-38. We found that PACAP could block the excitatory effects of KA in several brain areas (cortex: 89%, hippocampus: 36%, and thalamus: 50%). Moreover, we detected a lower level excitatory effect of PACAP alone (41%). The present results may explain the neuroprotective effects of PACAP observed in experimental models of glutamate (GLU)-receptor-mediated degenerative processes.