Differences in development influenced action, the scientists and their colleagues found. In animal experiments conducted at Duke University, both young and old rats performed significantly better on memory tasks if they received enough choline before birth compared with same-age rats whose mothers were fed choline-deficient diets. The latter showed deficits in the hippocampus and septums of their brains.
Because humans and rodents are so similar biologically, something comparable probably happens in humans, the investigators believe.
Now, working with nerve tissue derived from a human cancer known as a neuroblastoma, the UNC researchers have discovered why more choline causes stem cells -- the parents of brain cells -- to reproduce more than they would if insufficient choline were available.
A report on the findings will appear in the April issue of the Journal of Neurochemistry. Authors are doctoral student Mihai D. Niculescu and Dr. Steven H. Zeisel, professor and chair of nutrition at the UNC schools of public health and medicine. Dr. Yutaka Yamamuro, a former postdoctoral fellow in Zeisel's laboratory now with Nihon University in Japan, was a key contributor.
"We found that if we provided them with less choline, those nerve cells divided less and multiplied less," Zeisel said. "We then went on to try to explain why by looking at genes known to regulate cell division."
Scientists focused on cyclin-dependent kinase inhibitor 3 genes, which keep cells from dividing until a biochemical message turns the genes off, he said. They found exactly what they expected.
"We showed that choline donates a piece of its molecule called a methyl group and that gets put on the DNA for t
Contact: David Williamson
University of North Carolina at Chapel Hill