Objective: The aim of this work was to investigate the effect of different cytidine-5'-diphosphocholine (CDP-choline) concentrations (0.1-1 mM) on acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase activities in homogenates of adult rat whole brain and in pure (nonmembrane bound) enzymes.
Design and methods: Tissues were homogenized, centrifuged at 1000 xg for 10 min, and in the supernatant AChE activity and Na(+),K(+)-ATPase, Mg(2+)-ATPase activities were determined according to Ellman's method and Bowler's and Tirri's, respectively.
Results: After a 1-3 h CDP-choline preincubation, this substance induced a maximal stimulation of 20%-25% (p < 0.001) for AChE and 50-55% (p < 0.001) for Na(+), K(+)-ATPase, but it did not influence Mg(2+)-ATPase activity. One mM acetylcholine (ACh) resulted in an approximately 18% (p < 0.001) AChE inhibition by excess substrate in the brain homogenate, while 0. 01 mM noradrenaline did not influence Na(+),K(+)-ATPase activity.
Conclusions: CDP-choline can stimulate brain AChE and Na(+), K(+)-ATPase independently of ACh and noradrenaline. This enzymatic stimulation may be due to the transformation of CDP-choline to membrane phophatidylcholine. The above data could explain in part the clinical effects of this substance in some neuronal disturbances.