Nutrient alters gene activity in animals
rats permanently changed their behaviour by altering expression of
certain genes, US scientists have reported.
The findings, discussed in today's issue of the New Scientist, add further weight to the theory that foods humans eat can have a permanent impact on behaviour and health, also known as nutrigenomics.
Furthermore, emerging work suggests that supplements could be taken to halt the genetic effects that predispose people to certain diseases. Many diseases are, after all, caused by DNA damage.
A team led by Randy Jirtle of Duke University Medical Center previously demonstrated that the activity of a mouse's genes can be influenced by food supplements eaten by its mother just prior to, or during, very early pregnancy.
Following this, researchers at McGill University in Montreal, Canada, last year showed that rat mothers could influence the way offspring's genes are expressed even after it has been born. If a baby is not licked and nursed enough by its mother, chemical tags known as methyl groups are added to the DNA of a particular gene, they reported in Nature Neuroscience (vol 7, p847).
The affected gene codes for the glucocorticoid receptor gene, which mediates stress response. In poorly raised rats, the methylation damped down the gene's activity and the animals had higher levels of stress hormones and were less confident exploring new environments.
The researchers said at a meeting earlier this month that a food supplement can have the same effect on well-reared rats at 90 days old, in other words, well into adulthood.
The researchers injected L-methionine, a common amino acid and food supplement, into the brains of well-reared rats. The amino acid methylated the glucocorticoid gene, and the animal's behaviour changed.
"They were almost exactly like the poorly raised group," Moshe Szyf, told New Scientist.
Reversing this effect should also be possible, according to Szyf, who has shown that a chemical called TSA that is designed to strip away methyl groups can turn a badly raised rat into a more normal one.
Szyf says his study shows how important subtle nutrients and supplements can be.
"A huge number of diseases are caused by changes to how our DNA is expressed, and this opens up new ways of thinking about how to prevent and treat them," commented Rob Waterland, a researcher on the earlier mouse study.
But he warned that substances like methionine and TSA are likely to demethylate lots of other genes too and more work needs to be done to allow scientists to better target the methylation.
