The influence of cytidine on the endogenous pool of CDP-choline,CDP-ethanolamine,and CMP of the rat brain

Cold cytidine was intraventricularly administered into the brain of young rats, and its effect on CDP-choline, CDP-ethanolamine, and CMP pools followed for different time intervals and with various amounts of administered cytidine. The injected nucleoside produces a measureable increase of the concentrations of all three nucleotides. The increase produced by injecting 2.5 mol of cytidine for brain does not essentially change with higher doses of injected nucleoside, except for CMP, whose increase reaches a maximum with 5 mol of cytidine. A clear time dependence on cytidine administration was shown. The increases of the three nucleotide concentrations do not show a maximum till 60 min from administration of cytidine. The results indicate that administered cytidine is directly converted into CMP and CDP-bases and measurably increases their endogenous brain pools. The compound is likely to enter metabolic events connected with phospholipid metabolism in brain.