Choline is a full agonist in inducing activation of neuronal nitric oxide synthase via the muscarinic M1 receptor

The present study was designed to characterize the interaction of choline with the M(1) subtype of the muscarinic acetylcholine receptor. Using Chinese hamster ovary cells transfected with neuronal nitric oxide synthase and the cloned human M(1) receptor (CHO hM(1)/nNOS cells), we investigated choline's effects on production of nitric oxide and elevation of intracellular [Ca(2+)]. Choline showed the properties of a full agonist in inducing the sustained plateau of increased intracellular [Ca(2+)], although it was only a partial agonist in inducing the larger, transient [Ca(2+)] peak. Choline was also found to act as a full agonist in stimulating the production of nitric oxide. These results have implications for efforts in the clinical treatment of dementia.