What happens after a person receives a traumatic brain injury? Tissue damage and swelling often results in neural tissue being unable to receiving adequate levels of glucose which are required to “feed” the brain. This deprivation of energy can cause further injury to tissue, so often times an artifical supply of glucose is given to the brain to stave off those bad effects within the first few hours of injury.
Now this traditional food source may take a back-seat to lactate: the chemical that makes your tired muscles “feel the burn” and gives sour milk its, well, sourness. Researchers at UCLA have recently shown that the brain takes up lactate following an injury.
…the researchers found that in the first 12 to 48 hours following traumatic injury, the brain takes up and apparently consumes more lactate than at any other time. They discovered this by measuring the levels of lactate in blood entering and leaving the brain. To determine if lactate was being used by the brain, the researchers, in collaboration with George Brooks, a professor in the department of integrative biology at the University of California, Berkeley, labeled lactate with C13, a non-radioactive and stable isotope, then added it to the patient’s standard intravenous solution. The isotope served as a marker they could follow to see if the lactate molecule had produced carbon dioxide, the natural byproduct of lactate after use by the brain as fuel.
“Our preliminary tracer-based studies demonstrated the novel and unexpected finding of both lactate uptake and its utilization as fuel in traumatic brain injury,” Glenn said. “These results have led us to challenge the current conventional wisdom concerning the type of fuel the brain uses after injury to generate the energy for recovery.”
The theory goes that after a brain injury, neural tissue cannot utilize glucose normally, and glucose is directed to other uses. Instead, lactate is the preferred energy source during times of injury, which makes it a better candidate to administer to patients who need an artifical fuel source.
Below: Lactate uptake in the injured (top) versus (normal) brain.