Carbachol inhibits basal and forskolin-evoked adult rat striatal acetylcholine release.
Acutely dissociated adult rat striatal cholinergic neurons labeled with [3H]choline were used in a perifusion system to study muscarinic regulation of basal and forskolin-stimulated fractional [3H]acetylcholine ([3H]-ACh) efflux in the absence of synaptic modulation. Carbachol inhibited basal (40% maximal inhibition; IC50 approximately 0.7 microM) and forskolin-evoked release (75% inhibition; IC50 approximately 0.05 microM) in a concentration-dependent manner, and both carbachol actions were abolished with atropine. Thus, activation of striatal muscarinic cholinergic autoreceptors potently inhibits basal and adenylate cyclase-stimulated ACh release. Tonic inhibitory control of cholinergic activity by functional striatal circuitry apparently prevents detection of these important physiological interactions in slices or in situ.
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Department of Neurology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
D000109:Acetylcholine / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D018680:Cholinergic Antagonists / Q000494:pharmacology; D005576:Colforsin / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D003864:Depression, Chemical; D066298:In Vitro Techniques; D008297:Male; D017072:Neostriatum / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D051381:Rats
D018679:Cholinergic Agonists; D018680:Cholinergic Antagonists; D005576:Colforsin; D001285:Atropine; D002217:Carbachol; D000262:Adenylyl Cyclases; D000109:Acetylcholine