Nicotinic Cholinergic Receptors in Rat Brain

摘要

Nicotinic cholinergic receptors in rat brain were studied to determine theirdependence on intact disulfide bonds, their relationship to catecholamine and serotonin axons, and their regulation by cholinesterase inhibitors and nicotinic agonists. Reduction of disulfide bonds with dithiothreitol decreased the number of nicotinic binding sites labeled by (3H)acetylcholine (3 HAC). This effect was reversed by reoxidation of the reduced sulfhydryl groups to disulfide bonds. Lesioning catecholamine or serotonin axons with specific neurotoxins resulted in a decrease in the number of nicotinic receptor binding sites in the striatum and hypothalamus, indicating that in those brain areas the receptors are located on these axons. The number of nicotinic receptors is decreased by chronic inhibition of cholinesterase enzymes with diisopropylfluorophosphate or soman. In contrast, the receptor number is increased by chronic treatment with nicotine.