Brain, stress and cholesterol
The brain is responsible for cholesterol levels
Alexey Timoshenko, GZT.RUThe level of cholesterol in the blood is determined, among other things, by a neuropeptide called ghrelin, which, as earlier studies have shown, is associated with a stress response.
Thus, it is possible that scientists have come closer to understanding exactly how stress affects the heart and blood vessels.
A group of American scientists led by Matthias Tschöp from the University of Cincinnati found out that the brain is also responsible for the cholesterol content. More precisely, the hypothalamus, and even more precisely, the cells that react to the hormone ghrelin.
Ghrelin – what is it?
The name "ghrelin" may be unfamiliar even to those who received medical or biological education – the fact is that this substance was discovered only in 1999 by a group of Japanese scientists. They gave it a name, which is essentially an abbreviation of g rowth h ormone-rel eas in g peptide – a peptide that releases growth hormone. And initially it was believed that ghrelin acts only on the production of growth hormone.
In addition to the fact that "ghrelin" is an abbreviation, the discoverers of the hormone themselves in the annotation of their article (Masayasu Kojima et al., Ghrelin is a growth–hormone-releasing acylated peptide from stomach) mention another argument in favor of the name. They refer to the ancient Indo-European root ghre, which means "growth".
But more recent studies (since 1999, about 4 thousand works on ghrelin have been published!) It has been shown that this hormone is also associated with many other processes, from hunger to memory formation. Like many other signaling molecules in the body, ghrelin has many different functions, and therefore it would be incorrect to call it a "cholesterol hormone" now – we are talking only about the fact that, among all other factors, this peptide affects cholesterol levels.
Scientists call peptides substances that are chemically no different from proteins, except for the size of the molecules. A chain of up to hundreds of amino acids is usually called a peptide, and a large–sized protein. The prefix "neuro", sometimes added to the word, means that the peptide is synthesized by the cells of the nervous system. (In fact, ghrelin is synthesized by the cells of both the stomach, in which it was first discovered, and the kidneys - VM.)
How does it work?
In the June 6 issue of the journal Nature Neuroscience (Diego Perez-Tilve et al., Melanocortin signaling in the CNS directly regulates circulating cholesterol), researchers presented a description of the mechanism by which ghrelin regulates the number of cholesterol molecules in the blood. A series of experiments on mice showed that the molecules of this neuropeptide interact with receptors on the surface of the cells of the hypothalamus, an important component of the endocrine system.
Where is the hypothalamus located
Moreover, we are not talking about arbitrary receptors (each cell has many different protein molecules-receptors), but about a well-defined variety. The experiments of scientists have shown that if the methods of genetic engineering deprive an animal of MC4R receptors, which normally also react to the hormone melanocortin, all the effects of ghrelin disappear. Mice deprived of receptors interacting with ghrelin showed elevated cholesterol levels.
Ghrelin, interacting with MC4R receptors, affects the activity of the hypothalamus, and already the hypothalamus, with the help of a number of other hormones, affects the processing of cholesterol in the liver. Such a "two-story" chain is common for many other processes, but it has not yet been possible to trace a similar connection between the central nervous system and cholesterol levels.
What does it mean?
Of course, the fact that a hormone active in the brain affects cholesterol levels does not mean that it is possible to consciously change this level at any time. But this means that scientists may have got close to unraveling how the state of the nervous system is associated with cardiovascular diseases.
The endocrine system
(only the main organs and their functions are shown).
Elevated cholesterol levels, which are normally necessary for the body for a number of different processes, from the synthesis of sex hormones to the formation of nerve cells, have long been considered by doctors as one of the main risk factors due to plaques deposited in blood vessels. The formation of plaques on the walls of blood vessels leads, in turn, to their blockage, and this is fraught with a heart attack or stroke.
A number of works devoted to ghrelin and made before the study by American scientists also indicate that it is associated with a reaction to stress, up to the formation of depressive disorders. It is possible that it is not far from here to clarify the knowledge about how stress affects the heart and blood vessels.
Portal "Eternal youth" http://vechnayamolodost.ru08.06.2010