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Cholesterol in your brain is key to the
cell connections needed for memory and learning.
Past research has suggested that brain
"support cells" known as glial cells produce a substance
that allows the brain's nerve cells, or neurons, to communicate.
Cholesterol levels in the blood do not
determine the brain's supply, as blood cholesterol molecules
are too large to cross the blood-brain barrier. The blood-brain
barrier is a mechanism that strictly controls the type of
molecule allowed to enter into the brain from blood vessels.
Instead, glial cells appear to churn
out their own cholesterol supply. The researchers zeroed in
on cholesterol through experiments with cells in which the
lipid triggered the formation of synapses -- the connections
through which nerve cells communicate.
Thus
the availability of cholesterol appears to limit synapse development.
In addition, the investigators found
that, when cultured alone, neurons produced some cholesterol.
But only when glial cells were present was there a cholesterol
supply abundant enough for "massive" synapse formation.
According to the researchers, these findings
suggest that any "genetic or age-related defects"
in the brain's cholesterol use may impair the circuitry behind
mental functioning.
Science
November 9, 2001;294:1354-1357
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