18 June 2008

Another mechanism of alcoholic brain damage

Alcohol abuse can lead to irreversible damage to brain tissue caused by a deficiency of thiamine (vitamin B1). Earlier animal experiments have shown that alcohol can also cause degeneration of brain tissue by suppressing the activity of insulin and insulin-like growth factor (IGF).

Researchers at Brown University (Providence, Rhode Island, USA), working under the guidance of Dr. Suzanne de la Monte, based on a postmortem study of human brain tissue, confirmed that in humans, chronic alcohol abuse reduces the expression of genes necessary for the response of brain cells to these hormones. Violation of glucose intake into neurons causes neurodegenerative changes in the brain, similar to complications of type 2 diabetes mellitus.

Insulin is one of the most important hormones of the body, on which the viability and functioning of the cells of the whole body depend. The most well-known diseases associated with impaired synthesis or functioning of insulin are type 1 and type 2 diabetes. In recent years, there has been a growing interest in the scientific community in the effect of insulin on the functioning of the brain. To date, experts are of the opinion that insulin deficiency and loss of sensitivity to this hormone by brain cells are critical factors leading to neurodegeneration, including the development of dementia in Alzheimer's disease. As it turned out, alcohol significantly worsens this problem.

Before getting to the brain, alcohol passes through the liver, where it is subjected to the destructive action of enzymes, which significantly reduces the amount of ethyl alcohol entering the tissues. However, when drinking a large amount of alcohol or with chronic abuse of small doses, ethyl alcohol dissolves part of the lipids of the membrane of nerve cells. This disrupts the functioning of the insulin and insulin-like growth factor receptors included in the membrane and, accordingly, weakens the effectiveness of signals necessary to enhance energy production and maintain cell viability.

As part of the work, the authors analyzed brain tissue images of 6 male chronic alcoholics (average age 57.7 years) and 6 men without a diagnosis of alcoholism (average age 57.5 years) provided by the Tissue Resource Center of New South Wales, part of the University of Sydney. The study included samples of subjects who had not taken any narcotic drugs except alcohol during their lifetime.

Two brain regions that are the main targets of the neurotoxic effect of alcohol were selected for study: the cortex of the anterior superior region of the cerebellar worm and the anterior circular gyrus of the frontal lobe.

According to the results obtained, in chronic alcoholism, regions of the brain that are sensitive to the toxic effects of alcohol are characterized by pronounced resistance to insulin and insulin-like growth factor. The resistance of the frontal lobe and cerebellum regions to these hormones was accompanied by the destruction of cells and intercellular contacts, as well as a decrease in the levels of neurotransmitters necessary for learning, memorization and motor function.

The observed insulin resistance is similar to the manifestations of type 2 diabetes, which means that it is possible to alleviate the symptoms of alcoholic brain damage with drugs that increase the sensitivity of brain cells to insulin and insulin-like growth factor.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily


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