Choline chloride (also known as Vitamin B4) is a quaternary ammonium salt that is generally used as a constituent of lecithinum, acetylcholine and posphatidylcholine and also as an acyl group acceptor and choline acetyltransferase substrate. It is widely used in many biological processes, food and feeding additive, and in the preparation of deep eutectic solvents able to dissolve many metal salts.
Occurrence, co-occurrence and topographic distribution of choline acetyl transferase, Met-enkephalin and neurotensin in the stellate ganglion of the cat. 
Electropolishing of stainless steels in a choline chloride based ionic liquid: an electrochemical study with surface characterisation using SEM and atomic force microscopy. 
Studying Two Series of Ternary Deep Eutectic Solvents (Choline Chloride–Urea–Glycerol) and (Choline Chloride–Malic Acid–Glycerol), Synthesis and Characterizations. 
Choline Is an Intracellular Messenger Linking Extracellular Stimuli to IP3-Evoked Ca2+ Signals through Sigma-1 Receptors. 
 B.Jimenez, et al, Synapse, 2002, 43(3), pp 163-174.