The brain – Our most energy-consuming organ

May is the Month of the Brain, our most energy-consuming organs. Representing only 2% of the weight of an adult, the brain consumes 20% of the energy produced by the body.

Efficient energy supply is crucial for the brain, so that our memory, mobility and senses can function normally, says Professor David Attwell of University College London, who is researching the mechanisms by which the brain is powered.

Understanding these mechanisms may allow the development, in the long term, of innovative therapies for cerebrovascular disorders, Attwell says. Computers need a power supply to process information when typing a document or surfing the web and the same goes for the operations performed by brain cells.

“The brain is powered by the glucose and oxygen which are provided to it in the blood. Because nerve cells use lots of energy, when they are active they signal to nearby blood vessels, telling the vessels to dilate to deliver more substrates for energy production. These are the mechanisms we are studying.”

Failure of the energy supply to central nervous system tissue contributes to a wide range of neurological disorders, such as stroke and spinal cord injury.

These conditions have important social, economic and healthcare impact, as they are associated with increased disability and a larger risk of mortality, and they are rising in incidence in our increasingly ageing society.

It was long believed that cerebral blood flow was controlled by the large arterioles penetrating the brain from its surface.

A few years ago, Attwell and his team discovered an alternative vascular mechanism that might control the brain’s blood flow, mediated by a specific type of contractile cell called ‘pericytes’. The researchers believe these pericytes, situated on small capillary vessels, may play a crucial role in regulating energy to brain nerve cells.

“This hypothesis was controversial at that time but is increasingly being accepted by the scientific community,” Attwell says. “Building on this initial discovery, there is now evidence that may help to explain some of the nerve cell damage that occurs after a stroke.

“When a blood clot occludes a cerebral artery, nerve cells are damaged, but even if the clot is removed with medicines a long-lasting decrease of blood flow remains, and this can damage more nerve cells. This may be caused by an abnormal constriction of pericytes triggered by the initial stroke."

A report on the research was published by the European Research Council, which is funding the project.