Muscarinic autoreceptor regulates acetylcholine release in rat hippocampus: in vitro evidence

• Published in: Acta physiologica Scandinavica Vol. 108; no. 4; p. 347
• Main Authors: Nordström, O, Bartfai, T
• Format: Journal Article
• Language: English
• Published: England 01-04-1980
• Subjects: Acetylcholine - metabolism; Animals; Atropine - pharmacology; Carbachol - pharmacology; Feedback; Hippocampus - cytology; Hippocampus - metabolism; Male; Nerve Endings - metabolism; Rats; Receptors, Cholinergic - physiology; Receptors, Muscarinic - physiology; Synaptosomes - metabolism
• ISSN: 0001-6772
• DOI: 10.1111/j.1748-1716.1980.tb06543.x

Release of 3H-ACh from isolated nerve endings of rat hippocampus was evoked by incubation in Krebs-Ringer's buffer containing 25 or 35 mM potassium. The release was Ca2+-dependent and could be inhibited by Mg2+ (20 mM). The muscarinic antagonist, atropine (10(-10)-10(-6) M), enhanced 3H-ACh-release. The muscarinic agonist, carbachol (10(-5)-10(-3) M) inhibited 3H-ACh release via interaction with muscarinic receptors: this effect could be blocked by atropine (10(-6) M). The presence of the feed-back regulation of 3H-ACh release in a cell-free preparation provides further evidence that the presynaptic regulation is exerted by muscarinic autoreceptors localized on the cholinergic nerve ending itself. The feed back inhibition of the 3H-ACh release does not require the presence of intact neurons or neuronal loops as tetrodotoxin (2.5 x 10(-6) M) does not affect the above results.