Changes in the blood-brain barrier in multiple sclerosis

Structural changes in the area of the blood–brain barrier lead to a loss of integrity (intactness of the blood-brain barrier), which promotes the development of various diseases, such as multiple sclerosis (MS). In multiple sclerosis, inflammatory demyelinating processes in the central nervous system (brain and spinal cord) occur as a result of the passage of various immune cells (white blood cells and macrophages) into the brain. These demyelinating processes lead to the loss or degradation of the myelin sheath (myelin sheath of the nerve cells in the central nervous system, comparable to the insulation of a wire), causing various neurological symptoms (such as visual acuity disorders).

The exact process of white blood cell and macrophages crossing the blood-brain barrier is not yet fully understood. Fundamental to the development of multiple sclerosis is a dysfunction, which is characterized among other things by a reduced formation of cell contacts (comparable to a dense barrier). In multiple sclerosis, specialized cells of the blood-brain barrier produce different types of signal molecules (molecules that mediate processes). With the help of these, the crossing of various immune cells through the blood-brain barrier into the brain is possible. General information on this topic can be found here: multiple sclerosis

Changes of the blood-brain-barrier through alcohol

Alcohol, along with drugs and certain medicines, is able to penetrate the selective filtering barrier of the brain, the blood-brain barrier. Alcohol or excessive alcohol consumption leads to a disturbed integrity (integrity of the blood-brain-barrier), which promotes the development of neurodegenerative diseases (in which nerve cells die). The regular consumption of alcohol and its metabolic products causes structural changes in the blood-brain-barrier. Thus, regular and excessive alcohol consumption makes the selective filter barrier for toxic substances and disease-causing substances more permeable. This leads to structural and functional changes in the central nervous system (brain and spinal cord).

Change of the blood-brain-barrier through medication

Despite the selective protective function of the blood-brain barrier against the penetration of non-body substances into the brain via the blood, it is possible for certain substances to overcome the selective filter of the blood-brain barrier. Besides drugs and alcohol, certain drugs are also able to overcome the blood-brain barrier. The group of drugs that can cross the blood-brain barrier includes antidepressants, antiepileptic drugs (such as gabapentin) and the precursor of the messenger substance dopamine, L-dopa (levodopa).

Dopamine is a messenger substance that is partly responsible for feelings of happiness or concentration, for example. Dopamine is mainly used for the therapeutic, medicinal treatment of Alzheimer’s disease and in its actual form, cannot pass the blood-brain-barrier. In order to transport dopamine through the blood-brain barrier into the brain, a precursor of dopamine, L-dopa (levodopa), is used. Once in the brain, the L-dopa is converted to dopamine by the body’s own molecules to develop its effect. Overcoming the blood-brain barrier and improving the permeability of the blood-brain barrier for drugs used in the treatment of neurodegenerative diseases such as Alzheimer’s or amyotrophic lateral sclerosis (ALS) remains a current subject of medical research.