Cytidine and uridine increase striatal CDP-choline levels without decreasing acetylcholine synthesis or release

Abstract

Aims: Treatments that increase acetylcholine release from brain slices decrease the synthesis of phosphatidylcholine by, and its levels in, the slices. We examined whether adding cytidine or uridine to the slice medium, which increases the utilization of choline to form phospholipids, also decreases acetylcholine levels and release. Methods: We incubated rat brain slices with or without cytidine or uridine (both 25400 mu M), and with or without choline (20-40 mu M), and measured the spontaneous and potassium-evoked release of acetylcholine. Results: Striatal slices stimulated for 2 h released 2650 +/- 365 pmol of acetylcholine per mg protein when incubated without choline, or 4600 +/- 450 pmol/mg protein acetylcholine when incubated with choline (20 mu M). Adding cytidine or uridine (both 25-400 mu M) to the media failed to affect acetylcholine release whether or not choline was also added, even though the pyrimidines (400 mu M) did enhance choline's utilization to form CDP-choline by 89 or 61%, respectively. The pyrimidines also had no effect on acetylcholine release from hippocampal and cortical slices. Cytidine or uridine also failed to affect acetylcholine levels in striatal slices, nor choline transport into striatal synaptosomes. Conclusion: These data show that cytidine and uridine can stimulate brain phosphatide synthesis without diminishing acetylcholine synthesis or release.