title: Autoregulation of acetylcholine release in isolated hippocampal nerve endings.
abstract: The existence of presynaptic autoreceptors modulating acetylcholine release from central cholinergic nerve endings was investigated by using rat hippocampal synaptosomes in a superfusion system. The presence of exogenous acetylcholine, carbachol or oxotremorine in the superfusion fluid produced a dose-dependent inhibition of the release of [3H]acetylcholine elicited by 15 mM KCl in synaptosomes prelabeled with tritiated choline. The inhibition was counteracted by atropine. Another well known muscarinic agonist, bethanechol, had no effect on [3H]acetylcholine release. Our results indicate that central cholinergic nerve terminals possess autoreceptors of the muscarinic type for the control of acetylcholine release. Moreover, differences seem to exist between pre-and postsynaptic muscarinic receptors in the central nervous system.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009411:Nerve Endings / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D000109:Acetylcholine