In vivo regulation of muscarinic cholinergic receptors in embryonic chick brain.
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.
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002642:Chick Embryo; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D010095:Oxotremorine / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D013997:Time Factors
D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D010095:Oxotremorine; D011813:Quinuclidinyl Benzilate; D002217:Carbachol