High-fat diet during pregnancy could change offspring’s brain vasculature

Eating nutrient-rich foods with enough proteins, carbohydrates, and fats during pregnancy is important for the proper brain development of a fetus. However, a new collaborative study from the Tremblay Lab (Division of Medical Sciences) and the lab of Dr. Baptiste Lacoste (University of Ottawa) shows that it’s possible to have too much of a good thing.

In the resulting paper published in Communications Biology, first-author Dr. Maude Bordeleau and her team show that offspring born by individuals who consume a high-fat diet during pregnancy and nursing have significantly more blood vessels in their brains. They also show that these vessels branch out in the brain when those offspring reach adolescence.

Surprisingly, this increase does not seem to affect key cells important to the vasculature system’s ability to transfer nutrients and protect the brain. Dr. Bordeleau and her team could not see any abnormalities in endothelial cells, which line the blood vessels, or in pericytes, which help maintain the integrity of these vessels. Instead, a cell better known for its role in brain immune regulation – microglia — appeared to be implicated. Using state-of-the-art microscopy techniques, Dr. Bordeleau showed that these highly mobile immune cells were recruited to blood vessels in the brains of offspring exposed to a high-fat diet. As previous research shows that microglia are involved in angiogenesis, the formation of new blood vessels during brain development, she believes it’s possible that this increased recruitment of microglia is causing the hypervascularization.

"Prenatal exposure to a high-fat diet results in a chronic exposure of the fetal brain to low-grade inflammation, which is likely impacting microglia’s normal role in angiogenesis,” Dr. Bordelau explains.

So, could this affect how the brain functions? In their paper, the research team shows adult offspring who were exposed to a high-fat diet during development only displayed abnormalities in one test associated with repetitive and stereotypic behaviours, features linked to neurodevelopmental and neuropsychiatric disorders.

Dr. Bordeleau’s previous first-author paper showed a high-fat maternal diet also affects the organization of myelin, the fatty coat wrapped around neuronal axons, which could affect an offspring’s behaviour later in life. 

This body of work shows how nutrition during pregnancy can cause an unlikely player – microglia – to have a major impact on brain development.