In vivo regulation of muscarinic cholinergic receptors in embryonic chick brain

MR Meyer, MW Gainer and NM Nathanson

Prolonged treatment of chick embryos in vivo with the muscarinic agonists oxotremorine or carbachol leads to dose- and time-dependent decreases in the number of brain muscarinic acetylcholine receptors (mAChR) as measured by the specific binding of the potent muscarinic ligand L-[3H]quinuclidinyl benzilate to brain membranes. Maximal doses of agonists reduced the number of mAChR as much as 44%. Maximal loss of mAChR occurs 4 hr after treatment, but can be prevented or totally reversed within 24 hr by blockade of agonist-receptor interactions with muscarinic antagonists. After sustained in vivo oxotremorine treatment, brain mAChR show a decreased apparent affinity for agonists owing to a decrease in the affinities of both the high- and low-affinity agonist binding sites.

Volume 21, Issue 2, pp. 280-286, 03/01/1982
Copyright © 1982 by American Society for Pharmacology and Experimental Therapeutics