Mechanisms of muscarinic feedback regulation of acetylcholine release in rat hippocampus : an in vitro study

Abstract: The present study on dilute suspensions of synaptosomes from rat hippocampus yields evidence that feedback regulation of acetylcholine release in this preparation is exerted by a muscarinic autoreceptor localized on the cholinergic nerve ending itself. A possible model for the sequence of events which may take place at the cholinergic nerve ending is presented. Fresh surgical material has been used to demonstrate that the release of acetylcholine in the human cerebral cortex is also regulated by presynaptic muscarinic receptors. An in vitro test system for the study of drugs which affect the release of acetylcholine has been developed. This system was used to examine the effect of a novel cholinergic ligand, N-methyl-N(l-methyl-4-pyrrolidino-2-butynyl) acetamide, on 3 the release of H-acetylcholine. This ligand appears to act as a presynaptic antagonist and a postsynaptic agonist.