Glia: The Unsung Heroes of the Brain

Back to feature: The Complex Nature of the Brain

Who? Dr. Brian MacVicar Brain Research Centre and Department of Psychiatry, University of British Columbia

What’s a glial cell?
The most common cells in the brain are not actually nerve cells but glial cells. Glia include, astrocytes (the mysterious glia), microglia (the immune cell of the brain) and oligodendrocytes (the insulation of nerve fibres). Initially, astrocytes and the other glia were thought to be passive support cells for the nerve cells. Now, however, it is clear that all brain diseases involve glia that either possibly cause the disease or change the brain in reaction to the disease.

What's the research?
Dr. MacVicar is funded to study how glia change brain activity and ensure the health of nerve cells. His lab has shown that astrocytes control blood flow in the brain to ensure the nerve cells have enough energy. The researchers have also discovered that when there are problems with the energy supply to nerve cells, astrocytes then supply nutrients to nerve cells to keep them working. His research also shows how microglia, are constantly moving, making sure there are no problems with the health of nerve cells or their points of communication, called synapses. When damage is detected, the microglia quickly move in to stop the spread of damage and clean up the mess by removing either the damaged nerve cell or the synapse.

What's the impact?
Dr. MacVicar's research helps us understand how blood flow in the brain is maintained at a healthy rate. When the supply of nutrients (oxygen and sugar) is not sufficient to keep nerve cells and their communication via contacts called synapses working well, then dementia can occur. Sudden blockages of blood vessels in the brain during stroke can cause immediate nerve cell death. Understanding how blood flow in the brain is regulated by astrocytes will help us design effective ways to prevent these disorders in blood flow. In addition, the microglia can be harnessed to prevent damage from spreading in the brain and help clean up damage when it occurs.

Photo: Astrocyte calcium signals cause constrictions of brain arterioles. This image of brain tissue and blood vessels shows the result of stimulating one astrocyte. The stimulation causes an increase in calcium inside this cell which then spreads to other astrocytes. The effect can be seen by the spreading green signal in cells. This phenomenon is called a calcium wave. When calcium increases in the astrocyte touching the arteriole, a constriction is triggered that spreads with the calcium wave and then gradually recovers.

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