The brain continues to flush out waste products far into old age
Every day the brain produces around half a litre of fluid, cerebrospinal fluid (CSF), which protects the brain from injuries and is responsible for nutrient delivery and waste product removal from the brain cells.
The fluid thus serves a key function in the brain, and it was previously assumed that humans as well as rodents produce less CSF with age. As a result, the removal of waste products from the brain cells would decrease with age, leading to a decline in brain function.
Now, a group of researchers from the University of Copenhagen headed by Professor Nanna MacAulay from the Department of Neuroscience have shown that the same function in the brain of rats continues to work effectively in old age.
What is cerebrospinal fluid?
Cerebrospinal fluid is a clear fluid found in the brain cavity, the brain ventricles, responsible for delivering nutrients to the brain cells, removing waste products and protecting the brain from shocks and injuries.
Cerebrospinal fluid is produced in the brain ventricles in a network called the choroid plexus. The network never stops producing cerebrospinal fluid. In fact, it produces around half a litre a day and normally contains around 150 millilitres of fluid at any given time, which means that the fluid is replaced three to four times a day.
In a new study recently published in Nature Communications, the researchers studied CSF formation and absorption in rats aged one to 24 months and compared the results to structural and genetic studies of the tissue responsible for CSF production and the metabolism and oxygen consumption of this tissue.
And their results leave no room for doubt: While the brain and brain metabolism do change with age, the study showed that the brain tissue responsible for CSF production continues to work and produce this vital fluid.
Nanna MacAulay says, commenting on the surprising results: “The aim of the project was to learn precisely what caused the drop in CSF production and whether anything could be done to increase production in seniors and thus improve their cognitive abilities. However, according to all our data there is no age-related change at all in healthy rats. While previous research has argued that brain metabolism decreases with age, our data show that the metabolism of the tissue responsible for the secretion of CSF remains unaffected.”
The researchers still do not know whether patients suffering from neurodegenerative disorders such as Alzheimer’s disease have experienced a drop in CSF production and whether the disorder may thus be associated with a reduced ability to flush out toxins and waste products.
However, the new research results show that in healthy test animals the function of the tissue responsible for CSF production remains unaffected with age, and the same may be true of humans.
About the study
In short, the researchers measured the intracranial pressure, the production of brain fluid, how long it takes for it to pass through the brain, what the cells in the choroid plexus – the tissue responsible for CSF production – look like, the oxygen consumption and metabolism of this tissue and the RNA expressed. They used rats aged one, three, six, 12, 18 and 24 months.
Contact
Professor Nanna MacAulay, Department of Neuroscience
Phone: +45 3532 7566
Email: macaulay@sund.ku.dk
Professor Flemming Dela, Department of Biomedical Sciences
Associate Professor Blanca Aldana, Department of Drug Design and Pharmacology (now at Department of Veterinary and Animal Sciences)
Guest Researcher Jens Velde Andersen
PhD student Emil Winther Westi, Department of Drug Design and Pharmacology
Funded by: the Carlsberg Foundation, Lundbeck Foundation, Læge Sofus Carl Emil Friis og Hustru Olga Doris Friis’ Legat and the Novo Nordic Foundation.
Article by Communications Consultant Lisbeth Lassen