Sun, 16 May 2004 17:43:54 -0400 in article <[email hidden]>
Dr. Andrew B. Chung said:joe smigiel said:
1) What role does cholesterol play in the brain? I've
read it is the most prevalent molecule present in the
brain.
Cholesterol is used in the growing brain for myelination.
Once the brain is grown and fully myelinated, there is
probably very little need for additional cholesterol.
Brain needs cholesterol for proper functioning, see
for example
Mauch DH, Nagler K, Schumacher S, Goritz C, Muller EC, Otto
A, Pfrieger FW. CNS synaptogenesis promoted by glia-derived
cholesterol. Science. 2001 Nov 9;294(5545):1354-7. PMID:
11701931 [PubMed - indexed for MEDLINE] <URL:http://www.ncb-
i.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list-
_uids=11701931&dopt=Abstract>
"... CNS neurons produce enough cholesterol to survive
and grow, but the formation of numerous mature synapses
demands additional amounts that must be provided by
glia. Thus, the availability of cholesterol appears to
limit synapse development. This may explain the delayed
onset of CNS synaptogenesis after glia differentiation
and neurobehavioral manifestations of defects in
cholesterol or lipoprotein homeostasis."
Brain researchers discover bright side of ill-famed
molecule: nerve cells need cholesterol to establish
contacts. New perspectives for the treatment of brain
lesions Centre de Neurochimie in Strasbourg, Press release
November 8, 2001 <URL:http://www.cnrs.fr/cw/en/pres/compres-
s/BienfaitCholesterol.htm>
"Cholesterol, which is an essential component of the
plasma membrane, has a bad reputation, because high
cholesterol levels in the blood raise the risk for
atherosclerosis and consequently heart attack and
stroke. The identification of cholesterol as
synaptogenic factor shows a surprisingly beneficial side
of this infamous molecule. The new results suggest that
the availability of cholesterol in the brain limits the
extent of synaptogenesis and that a defective
cholesterol metabolism in the brain impairs its
development and function.
Neurons appear to produce enough cholesterol to survive
and to grow, but require external cholesterol to form a
sufficient number of synaptic contacts. Since cells in
the brain cannot access the cholesterol supply in the
blood, they need to synthesize cholesterol by
themselves. According to the new results, glial cells
produce surplus cholesterol and deliver it to neurons
via lipoproteins. This dependence indicates a new role
for glial cells as cholesterol providers and could
explain why synaptogenesis in the CNS occurs after the
differentiation of macroglial cells."
Vital ingredient for a healthy memory BBC News, Thursday, 8
November, 2001 news.bbc.co.uknewsOpen ↗
id_1645000/1645372.stm
"Cholesterol plays a crucial role in making sure that
the brain works properly.
The compound is notorious for clogging up the arteries,
leading to heart disease and stroke.
But scientists have found that it stimulates the nerve
cells of the brain to make the connections that are
essential to learning and memory.
The brain does not obtain cholesterol from the blood.
The molecules are too big to pass across the blood-brain
barrier which provides a frontline defence against toxic
substances.
New research by French and German scientists suggests
that instead cholesterol is secreted by support cells
within the brain.
[...]
The scientists speculate that genetic or age-related
problems in the cholesterol mechanism might play a role
in neurodegenerative diseases such as Alzheimer's.
Dr Pfrieger said: "Cholesterol is necessary in large
quantity if nerve cells are to make connections with
each other.
"A defective cholesterol metabolism in the brain may
impair its development and function.""
--
Matti Narkia