Guest guest Posted June 8, 2004 Report Share Posted June 8, 2004 The statement that there is hardly anything that doesn't pass through the BBB is incorrect. It would make such a barrier completely useless. A substance is checked at the 'border' for suitability to be allowed or denied entry. This is for the protection of the brain. An example which will illuminate a currently universally ignored problem as follow: The human liver produces most of the cholesterol that the body requires, constantly. Food cholesterol is almost irrelevant. Cholesterol molecules are very large and they are not allowed entry into the brain. The 'guards' at the BBB take one look and issue a refusal notice. Now, since the brain needs and is totally dependent on cholesterol what is the story? The brain makes its own through its glial cells without which we would die. Now, if a doctor, with his/her omnipotent wisdom prescribes statins for the (idiotic and totally unnecessary ) purpose of reducing blood cholesterol these statins prevent the liver from making cholesterol. So far so good, but they also travel (out of curiosity) to the BBB and demand access. No problem, the molecular size is acceptable, no other reasons and they are admitted without fuss. Wherupon they start their job of destroying the brain's vital cholesterol. Brave new medicine! Quote Link to comment Share on other sites More sharing options...
Guest guest Posted June 9, 2004 Report Share Posted June 9, 2004 @@@@@@@@@@@@@@ > The human liver produces most of the cholesterol that the body > requires, constantly. Food cholesterol is almost irrelevant. > Cholesterol molecules are very large and they are not allowed entry > into the brain. The 'guards' at the BBB take one look and issue a > refusal notice. > Now, since the brain needs and is totally dependent on cholesterol > what is the story? > The brain makes its own through its glial cells without which we > would die. @@@@@@@@@@@@@@ I had the impression that an increase in dietary cholesterol was linked to slower mental degeneration in some cases for elderly patients. Maybe there is no link, but if so, what could the mechanism be? The common wisdom is that there is a homeostasis between dietary cholesterol and liver-made cholesterol, such that dietary cholesterol tweaks can compensate for inadequate liver synthesis, but your observation suggests there is no such interaction between dietary cholesterol and brain-made cholesterol. This is a point of clarification that I haven't encountered in the non- specialist discussion of cholesterol, which may sometimes misrepresent the positive aspects of dietary cholesterol. I don't have any physiology background, so any clarification is helpful. Mike SE Pennsylvania The best way to predict the future is to invent it. --Alan Kay Quote Link to comment Share on other sites More sharing options...
Guest guest Posted June 9, 2004 Report Share Posted June 9, 2004 > @@@@@@@@@@@@@@ > > The human liver produces most of the cholesterol that the body > > requires, constantly. Food cholesterol is almost irrelevant. > > Cholesterol molecules are very large and they are not allowed entry > > into the brain. The 'guards' at the BBB take one look and issue a > > refusal notice. > > Now, since the brain needs and is totally dependent on cholesterol > > what is the story? > > The brain makes its own through its glial cells without which we > > would die. > @@@@@@@@@@@@@@ > > I had the impression that an increase in dietary cholesterol was > linked to slower mental degeneration in some cases for elderly > patients. Maybe there is no link, but if so, what could the > mechanism be? The common wisdom is that there is a homeostasis > between dietary cholesterol and liver-made cholesterol, such that > dietary cholesterol tweaks can compensate for inadequate liver > synthesis, but your observation suggests there is no such interaction > between dietary cholesterol and brain-made cholesterol. This is a > point of clarification that I haven't encountered in the non- > specialist discussion of cholesterol, which may sometimes > misrepresent the positive aspects of dietary cholesterol. I don't > have any physiology background, so any clarification is helpful. > > Mike > SE Pennsylvania > You are correct with your comments on the liver making enough cholesterol for the needs of the body and the dietary intake of chol.influencing how much is needed to be made. I had wanted to emphasize the point that dietary cholesterol in the end matters little and it is futile to try to control total cholesterol through dietary means. As to the brain's production of cholesterol for 'domestic' use, there is little reason that it would share with the greater territory of the body. I suppose in a pinch the brain could crank up its production to 'help out' but this is not observed nor is it very likely. All the answers are not in, of course, there still exists some controversy on whether the BBB is actually always categorically closed to liver-produced cholesterol. The intriguing question remains: Is the BBB equally tough on substances wanting to cross in both directions? > The best way to predict the future is to invent it. --Alan Kay Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.