Introducing the brain: supplying enough choline (Introduction)

by David Turell , Friday, September 27, 2024, 16:43 (57 days ago) @ David Turell

A vital process:

https://www.sciencemagazinedigital.org/sciencemagazine/library/item/27_september_2024/4...

"Each mammalian cell contains more than one billion phospholipids. More than half of these lipids are phosphatidylcholine. The sheer density of cells in the brain endows it with an immense hunger for this critical cellular component. In 1956, Eugene P. Kennedy discovered that phosphatidylcholine is synthesized de novo through a series of three enzymatic steps, in what is now known as the Kennedy pathway. The fatty acid and glycerol moieties of phosphatidylcholine can be synthesized by cells, but the choline head group is a water-soluble molecule that must be obtained from dietary sources. Adults are advised to consume 400 to 500 mg of choline per day from choline-rich food sources, such as eggs, fish, and broccoli (2). This number increases to 700 mg for pregnant women, who must support both their own needs and the needs of their growing babies.

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"...the blood vessels that permeate the brain have evolved an additional layer of defense called the blood-brain barrier (BBB). Endothelial cells that line these blood vessels are more tightly packed and exhibit less transcytosis, which restricts the passage of molecules from the blood into the brain (4). Entry into the brain through these cells is mediated by highly vigilant transporter proteins. Each of these proteins has a distinct three-dimensional structure with binding sites specifically tailored to match the shapes and electrochemical properties of particular molecules that require delivery to the brain.

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"these experiments demonstrate that FLVCR2 is the brain’s major importer of choline

"As an MFS transporter, FLVCR2 uses a rocker switch mechanism to transport choline, which involves a large rigid-body rocking movement between an outwardfacing state (OFS) and an inward-facing state (IFS), to provide centrally bound choline with alternating access to either side of the membrane...These structures reveal that choline binds to a highly conserved site in the center of FLVCR2, where it interacts with several aromatic residues and is further stabilized by an intricate hydrogen bonding network, and demonstrate how this molecular machine moves to mediate the passage of choline across the BBB. (my bold)

"Our work has identified and characterized the transporters responsible for importing essential omega-3 fatty acids and choline into the brain and has revealed the atomic details of their transport. These findings clarify how the brain obtains critical nutrients to enable its growth and maintenance throughout life. They also provide insights and new therapeutic avenues for the treatment of neurological diseases that are associated with compromised nutrient delivery, such as Alzheimer’s disease, or overstimulated growth, such as glioblastoma

"Nutrient delivery to the brain is a markedly intricate process. From the moment that we consume food to the delivery of vital nutrients to the brain, a complex system works tirelessly to ensure that our brain functions optimally. By understanding this process, we can better appreciate the importance of a balanced diet and healthy lifestyle in maintaining brain health. So, the next time that you enjoy a meal, remember that you are fueling the most sophisticated organ in your body—helping it to think, feel, and thrive."

Comment: the article does not note that the brain requires a massive caloric intake every day as well as the choline requirement. My bold highlights the intricacies of the biochemical mechanisms. It is another piece of evidence for design.