RT Journal Article SR Electronic T1 Regulation of brain acetylcholine concentration by muscarinic receptors. JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 243 OP 248 VO 246 IS 1 A1 V H Sethy A1 J W Francis YR 1988 UL http://jpet.aspetjournals.org/content/246/1/243.abstract AB The cholinergic agonists oxotremorine, oxotremorine-1, oxotremorine-3, arecoline and BM 123 (N-[4-(2-chloroethylmethylamino)-2-butynyl]-2-pyrrolidone) were used to investigate the role of muscarinic receptors in the regulation of acetylcholine (Ach) concentration in the whole mouse brain. Intravenous oxotremorine, oxotremorine-1, oxotremorine-3 and arecoline dose-dependently decreased ex vivo binding of [3H]oxotremorine-M and correspondingly increased brain Ach concentration. The correlation coefficient between the ED50's of these two parameters was 0.90. BM 123 induced percentage of reduction in muscarinic receptors correlated with percentage of decrease in response of oxotremorine, for increasing brain Ach concentration. These results indicate that the muscarinic receptor system involved in the regulation of brain Ach levels may lack spare receptors.