Figure 5.

Interconnection of OCU metabolism, Kennedy pathway, and SM cycle. CDP-choline is required for de novo biosynthesis of phosphatidylcholine (PC) in the Kennedy pathway. PC is used to convert ceramide to SM in the SM cycle. Diacylglycerol (DAG) and phosphorylcholine, two products of SM biosynthesis and degradation, can be used to regenerate CDP-choline and PC. Ethanol-induced shortage of CDP-choline or PC, or hydrolysis of SM, will result in reduced SM and increased ceramide levels. CDP-choline can either be directly administered (citicoline) or synthesized from choline. Choline can be regenerated from betaine through OCU metabolism