Impact of diet on brain specific gene expression, adult neurogenesis and behaviour
NOVEMBER 07, 2007
Dr Sandrine Thuret from the Centre for the Cellular Basis of Behaviour & the MRC Centre for Neurodegeneration Research, at the Institute of Psychiatry, King's, has recently presented her work Brain specific gene expression, adult neurogenesis and behaviour are altered by diet at this year's annual Society for Neuroscience meeting in San Diego, California.
Recent research shows that the production of new brain cells may be crucial for antidepressants to be effective and that the medication's effectiveness is strongly influenced by age. What's more, meal frequency, type of food, and physical exercise affect the brain's ability to manufacture these new cells.
Thuret was one of several academics presenting on the different modulators of neurogenesis in the adult brain. Her work looks at the effects of calories consumed and meal frequency in the diet, alongside colleagues reporting on the effects of age and exercise. Her laboratory discovered that independent of calorie intake, meal frequency and food content both play important roles in neurogenesis in the hippocampus.
"Our cell culture data show an impressive increase of 40 percent of adult hippocampal neurogenesis upon addition of omega-3 fatty acids into the cell culture dish," Thuret says.
In laboratory animals, Thuret found that meal frequency is more important than calorie intake in regulating adult hippocampal neurogenesis. "Indeed, adult female mice fed a calorie-restricted diet of 10 percent less than normal-fed mice did have a higher level of newborn cells in the hippocampus," she says. But few of these new cells were neurons. In mice fed every other day, which led to a similar decrease of 10 percent of calories over two days- neurogenesis and learning abilities increased.
"Remarkably, we also showed that diet has an influence on the level of expression of genes in the brain," Thuret says. Some of these genes, which are critical for cognition, are the same genes that are regulated by intermittent fasting.
Additional research on these genes may help identify the cellular and molecular mechanisms underlying the influence of food intake on neurogenesis in the adult brain and in learning and memory. The search for neurobiological mechanisms that link nutrition, adult neurogenesis, and behavior is a new emphasis in biomedical research, prompted in part by recent findings from laboratory rodent studies indicating that a reduced calorie diet promotes healthy aging.
"It is well recognized that dietary restriction increases life span, reduces neuronal damage, enhances learning abilities, and improves behavioral outcome in experimental animal models of neurodegenerative disorders," Thuret says.
But not well recognized is how these effects are achieved. In her search for the answers, Thuret and her colleagues selected mice as a lab model, since previous research had associated neurogenesis in the hippocampus with improved memory and learning abilities in rodents.
Each of the three groups of mice in the study included 20 adult females, half of which were used for histology and gene expression data. The remainder were used for behaviour research. For three months, one group ate at will, the second group ate every other day, and the third were fed a diet in which calories were restricted by 10 percent every day.
The behavioral tests included the Morris water maze (in which scientists measure animals' ability to learn and use visual cues to find a hidden platform) and object recognition tests (in which the ability of the mice to remember their encounter with different objects over time is measured). "We studied their ability to learn and remember, and we looked at the amount of newborn neurons in their brain upon different diets," Thuret says. "Then we correlated the changes with the regulation of the expression of their genes."
"There is much to learn about the effects of food intake-for example, how much, how often, what, and when-on the cellular and molecular biology of the nervous system and its functional capabilities, reflecting cognitive performance in both normal and ill circumstances," Thuret says.
"This area of investigation needs attention because a better understanding of the neurological mechanisms by which nutrition affects health may lead to novel approaches for disease prevention and treatment."
Thuret S, Morisse B, Ahmet S, et al. Brain specific gene expression, adult neurogenesis and behaviour are altered by diet. Session 315.26/HHH26, Neuroscience - San Diego CA, 2007 Nov 7.
To read the press release including the work on Neurogenesis of the other 3 academics interviewed follow the link: