Scientists have found that astrocytes, cells that surround nerve cells and all blood vessels in the brain, play a primary role in regulating blood flow within the brain, and hold promise as a target for new drug therapies.
The findings of the two-year study, made by lead researchers, Sean Mulligan and Brian MacVicar at the University of British Columbia, were made using a new technique developed to study brain blood flow. This allowed the team to discover that a rise of calcium within the astrocytes instructs the blood vessels to constrict which altered the blood flow.
Brain blood flow supplies energy for brain activities and while vessel contraction and dilation is a normal part of brain functioning, improperly regulated flow can result in brain disorder or damage. However, calcium flow in the brain is not influenced by diet.
Dr. Antoine Hakim, CEO and Scientific Director of the Canadian Stroke Network expressed excitement towards this latest study by adding: "This powerful research gives us new targets against which to develop a new generation of drugs to minimize stroke damage to the brain."
"This is an exciting find because it gives us a new site to investigate," said MacVicar. "This discovery highlights the complex communication between astrocytes and blood vessels, and research can now be focused on understanding and controlling these communication pathways pharmacologically."
The discovery that astrocytes cause constriction upsets earlier theories that astrocytes might cause vessels to dilate. The researchers hope to take the next step in the research by determining how to block the calcium in astrocytes to reduce damage caused by inadequate brain blood flow. MacVicar estimated that treatments might be available within five to 10 years.
There are an estimated 18 million people in the world with dementia, accordng to the charity Alzheimer's Disease International, which estimates that by 2025 this figure could increase to 34 million. And finding a treatment that could delay onset by just five years could reduce the number of individuals with Alzheimer's disease by nearly 50 per cent after 50 years.
The research, entitled 'Calcium transients in astrocyte endfeet cause cerebrovascular constrictions,' is published in Nature 431, 195 - 199 (09 Sep 2004) and is available online.