Dietary choline supplementation in pregnant rats increases hippocampal phospholipase D activity of the offspring

Supplementation with choline during pregnancy in rats causes a long-lasting improvement of visuospatial memory of the offspring. The biochemical mechanism of this effect may be related to the function of choline as a precursor of phosphatidylcholine (PC), the substrate of a receptor-stimulated enzyme, phospholipase D (PLD). PLD activation initiates the sequential formation of two intracellular messengers, phosphatidic acid and 1,2-sn-diacylglycerol. We hypothesized that prenatal choline status may cause long-term modulation of PLD-catalyzed PC hydrolysis in the hippocampus, a brain region implicated in visuospatial memory functions. PLD activity was determined in hippocampal slices prelabeled with [3H]glycerol or [3H]oleic acid by measuring the PLD-catalyzed formation of [3H]phosphatidylpropanol in the presence of 1-propanol. Slices were obtained from male pups born to mothers consuming a control diet, a choline-supplemented diet, or a choline-free diet from days 11 to 17 of pregnancy. The radiolabeling of phospholipid classes was unaffected by the treatments. Prenatal choline supplementation significantly increased basal PLD activity in [3H]glycerol-labeled slices [by 46% of controls on postnatal day (P) 7 and by 36% on P21], and [3H]oleate-labeled slices (by 91% on P7), as well as glutamate-stimulated PLD activity in [3H]oleate-labeled slices (by 60% on P7). Prenatal choline deficiency failed to alter PLD activity. The actions of choline apparently required intact cells because in vitro assays of PLD activity in hippocampal homogenates, using fluorescent NBD-PC as substrate, revealed no differences between groups. The results show that prenatal choline supplementation up-regulates basal and receptor-stimulated PLD activity in the hippocampus during postnatal development.