Acıbadem Üniversitesi Sağlık Bilimleri Dergisi 2010 , Vol 1, Issue 2
Roles of Choline On Central and Peripheral Cholinergic Neurons and Cholinergic Neurotransmission
İsmail Hakkı Ulus1, Mehmet Cansev2
1Acıbadem Üniversitesi Tıp Fakültesi, Farmakoloji ve Klinik Farmakoloji Anabilim Dalı, İstanbul, Türkiye
2Uludağ Üniversitesi Tıp Fakültesi, Farmakoloji ve Klinik Farmakoloji, Bursa, Türkiye
Choline, a quaternary amine, is an essential precursor for the neurotransmitter acetylcholine (ACh) and the major membrane constituent phosphatidylcholine (PC). Choline is also metabolized to betaine, which provides a source of methyl groups for the regeneration of methionine and S-adenosylmethionine. The present review will mainly focus on the roles of choline on cholinergic neuronal functions. The main source of free choline for cholinergic neurons to synthesize acetylcholine is blood circulation. Plasma choline concentrations can vary over a six-fold range (10- 60 μM) depending on the choline contents of the foods ingested. Choline concentrations in the circulation can increase up to 200-500 μM following treatment with pharmacological doses of choline. Since choline acetyltransferase [ChAT]), the enzyme that converts choline to ACh, is poorly saturated with its choline substrate, increases in plasma choline can enhance the formation and the release of ACh. Choline, at sufficiently high concentrations (i.e., at 0,5-100 mM), aslo interacts with muscarinic and nicotinic acetylcholine receptors as an agonist. Choline treatments result with increases in neurotransmitter acetylcholine synthesis and release, and enhancements in central and peripheral muscarinic and nicotinic cholinergic neurotransmission. Choline produces several physiological, pharmacological and neurochemical effects in cholinergic nature which will be discussed here. Keywords : Choline, precursor, acetylcholine, agonist, cholinergic transmission