TY - JOUR T1 - In vivo regulation of muscarinic cholinergic receptors in embryonic chick brain. JF - Molecular Pharmacology JO - Mol Pharmacol SP - 280 LP - 286 VL - 21 IS - 2 AU - M R Meyer AU - M W Gainer AU - N M Nathanson Y1 - 1982/03/01 UR - http://molpharm.aspetjournals.org/content/21/2/280.abstract N2 - 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. ER -