ACETYLCHOLINE-RELEASE IN THE HIPPOCAMPUS - EFFECTS OF CHOLINERGIC ANDGABAERGIC COMPOUNDS IN THE MEDIAL SEPTAL AREA

The medial septal area (MSA) contains cholinergic and GABAergic neuron s that send projections to the hippocampus. These neurons have both ch olinergic and GABAergic receptors. This study was designed to determin e the effects of intraseptal infusions of cholinergic and GABAergic dr ugs, which alter mnemonic processes, on hippocampal acetylcholine (ACh ) release. Hippocampal ACh release was assessed using in vivo microdia lysis and HPLC-EC. Oxotremorine and scopolamine produced a dose-depend ent decrease in hippocampal ACh release. Muscimol decreased hippocampa l ACh release at both high and low doses, although not in a dose-depen dent manner. The effects of scopolamine and muscimol are consistent wi th a role of ACh in mnemonic processing.