Effect of cytidine(5')diphosphocholine (CDP-choline) on the total urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) by rats and humans.

We examined the effects of orally administered cytidine(5')-diphosphocholine (CDP-choline) on the total levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) in human and rat urine. Four subjects who had been on a low-choline diet (less than 1 gm/day) for 24 hours received three doses of CDP-choline (2 gm each) at 8 a.m., 10 a.m., and noon; urines were collected at two-hour intervals after each dose. Rats received water for three days; then CDP-choline (100 mg/kg) or equimolar doses of choline for five days; then water again for three more days. Twenty-four hour urine samples were collected on each day of the study. The levels of MHPG in human urine increased by 45-68% when subjects were receiving CDP-choline (p less than 0.01). CDP-choline, but not choline, also elevated urinary MHPG significantly in rats (p less than 0.01). These data suggest that CDP-choline enhances norepinephrine release, and that this action may be mediated by more than just its choline content.