Molecule That Transports DHA Into the Brain Discovered
DHA in the brain: here is the molecule that transports it
It is called Mfsd2a and it is the protein responsible for the uptake of DHA (docosahexaenoic acid) by the brain. The Omega-3 is captured and transported into the brain, where it is found in high concentrations, by the transport molecule that is exclusively present in the cells of the blood vessels of the central nervous system.
This is the discovery made by a team of researchers from the National University of Singapore, published in the prestigious journal Nature.
DHA: the most important Omega-3 for the brain
DHA is an Omega-3 mainly found in fatty fish and marine oils. It is essential for brain growth and for the development and maintenance of normal cognitive functions, and it is the fatty acid found in the highest concentration in neuron membranes. During embryonic development, maternal DHA is absorbed through the placenta, passing from mother to fetus; in adults, it mainly derives from foods consumed in the diet. DHA cannot be synthesized in nervous tissue and must be imported across the blood-brain barrier, i.e., the structure formed by tightly connected endothelial cells around the blood vessels of the brain. Such mechanisms of DHA uptake have so far remained unclear.
A protein transports DHA across the blood-brain barrier
The molecule Mfsd2a belongs to the family of transporter proteins that allow the movement of certain substances into and out of cells. To clarify its role, Prof. Silver and his team caused specific genetic mutations in laboratory mice, making them unable to produce Mfsd2a. Animals without the protein showed markedly reduced levels of DHA in brain tissue, significant loss of neuronal cells in the hippocampus and cerebellum, cognitive deficits, and reduced brain growth (microcephaly). Unexpectedly, the study revealed that Mfsd2a transports DHA in the form of lysophosphatidylcholine, i.e., phospholipids produced by the liver and circulating in high amounts in the blood. This represents an interesting discovery since lysophosphatidylcholine was previously considered toxic to cells and its role in the body was unclear.
The main mechanism of DHA uptake and transport
The results showed that the absence of the Mfsd2a protein significantly reduced the passage of DHA, in the form of lysophosphatidylcholine, from plasma to the brain, demonstrating that Mfsd2a is necessary for the absorption of Omega-3. The study allowed the creation, for the first time, of a genetic model characterized by DHA deficiency, which enables the study of the effects of this deficit. The new information obtained could promote the development of technologies to incorporate DHA more effectively into food. The mechanism could then be exploited to maximize nutritional effects and increase brain growth and functions. This is especially important for premature babies who did not receive enough Omega-3 during fetal development.
Source: Long N. Nguyen, Dongliang Ma, Guanghou Shui, Peiyan Wong, Amaury Cazenave-Gassiot, Xiaodong Zhang, Markus R. Wenk, Eyleen L. K. Goh & David L. Silver. “Mfsd2a is a transporter for the essential omega-3 fatty acid docosahexaenoic acid”. Nature 509, 503–506 (22 May 2014) doi:10.1038/nature13241
