Effects of cholinergic agonists and antagonists on unit discharge of dorsal hippocampal CA1 area in rat

The effects of icv cholinergic agonists (acetylcholine 6 micrograms, physostigmine 10 micrograms, and nicotine 20 micrograms) and cholinergic antagonists (scopolamine 40 micrograms and hexamethonium 250 micrograms) on 174 cells unit discharges of the dorsal hippocampal CA1 area in 42 rats were studied. The frequencies of the unit discharges were increased in 41 cells over 84 cells by icv M or N receptor cholinergic agonists, but reduced in 22 cells over 42 by M or N receptor cholinergic antagonists. After the electrolytic lesion of the septal region, the effects of acetylcholine and nicotine on unit discharges disappeared. The results indicated that the cholinergic agents changed the electric activity of cholinergic sensitive neurons via the septum-hippocampal cholinergic pathway.