Characterization of muscarinic autoreceptors in the rabbit hippocampus and caudate nucleus.
Oxotremorine-induced inhibition of electrically evoked release of 3H-acetylcholine from brain slices preincubated with 3H-choline was used to characterize muscarinic autoreceptors in rabbit hippocampus and caudate nucleus. From the shifts to the right of the concentration-response curves of oxotremorine in the presence of muscarinic receptor antagonists, the following pKB values [95% C.I.] were determined in the hippocampus: tripinamide: 8.7 [8.5, 8.8]; himbacine: 8.4 [8.3, 8.5]; AQ-RA 741: 8.3 [8.2, 8.5]; 4-DAMP: 8.2 [8.0, 8.3]; hexahydrosiladifenidol: 7.4 [7.2, 7.5]; AF-DX 116: 7.3 [7.1, 7.4]; pirenzepine: 6.8 [6.6, 7.0]; and PD102807: 6.3 [6.0, 6.5]. In the caudate nucleus: tripinamide: 9.1 [8.9, 9.2]; 4-DAMP: 8.3 [8.2, 8.5]; himbacine: 8.1 [8.0, 8.2]; AQ-RA 741: 8.1 [8.0, 8.3]; hexahydrosiladifenidol: 7.3 [7.2, 7.4]; AF-DX 116: 7.1 [7.0, 7.2]; pirenzepine: 6.7 [6.6, 6.8]; and PD102807: 6.5 [6.2, 6.8]. These pKB values fit best to literature values for M2 receptors, suggesting that the muscarinic autoreceptor of the rabbit hippocampus and caudate nucleus is the m2 gene product.
Stoll
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Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universitaät, Neuropharmakologisches Labor, Hansastrasse 9A, D-79104 Freiburg, Germany.
Schwarzwälder
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U
Johann
S
S
Lambrecht
G
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Hertting
G
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Feuerstein
T J
TJ
Jackisch
R
R
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D017660:Autoreceptors / Q000378:metabolism*; D002421:Caudate Nucleus / Q000378:metabolism*; D002794:Choline / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D018721:Muscarinic Agonists / Q000008:administration & dosage / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009994:Osmolar Concentration; D010095:Oxotremorine / Q000008:administration & dosage / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000378:metabolism*
D017660:Autoreceptors; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010095:Oxotremorine; D002794:Choline; D000109:Acetylcholine