Lactate containing astrocytes important for long-term memory
Scientists have discovered astrocytes that transport lactate for brain energy play an important role in long-term memory. The discovery may help with improved treatment for Alzheimer's disease. In new findings, researchers say lactate transported from the specialized brain cells is more important for cognitive functioning than previously known.
New understanding of lactate transport could provide new therapies for memory loss
The researchers say the findings are important and could lead to new therapies to help individuals with neurocognitive decline from Alzheimer's disease as well as patients with neurodegenerative diseases and even diabetes.
Cristina Alberini, PhD, Professor of Neuroscience at Mount Sinai School of Medicine explains, “Little is known about the role of astrocytes in cognitive functions. The results further prove that astrocytes are much more actively involved in memory formation than previously thought, and that lactate is a promising target for investigating novel mechanisms that may be the cause of deficits of long-term memories.”
Astrocyte brain cells that are star shaped cells that and known to provide support and structure to neurons and blood vessels in the central nervous system. The cells also store glycogen that is released as needed for neuronal synaptic activity. When brain damage occurs, astrocytes proliferate and take up space to restore the blood-brain barrier. Until now researchers didn't know the specialized cells also played a role in higher brain function and memory.
To find the importance of lactate release from astrocytes, the scientists blocked glycogen breakdown with an injection in the brains of rats that causes amnesia. Prior to the injection, some of the rats "learned" to avoid a place where they had an unpleasant experience. In another group of rodents, the researchers injected the amnesic compound combined with lactate.
The rats given the compound that blocked lactate had long-term memory loss, but those given lactate in addition to the blocking agent showed no memory impairment. When they repeated the study using glucose instead of lactate, the scientists saw no improvement in long-term memory and a transient change when they used triple the amount of glucose.
“These results show that when a lot of energy is required, such as in long-term memory formation, glucose is not sufficient, or is less efficient, for long-term formation and maintenance,” said Dr. Alberini. “Now that we know that lactate has this critical function, we can study why it does and why glucose does not have the same impact.”
The researchers plan more studies to see how their findings can be applied clinically. The findings show the importance of lactate for long-term memory that is released by astrocytes and previously unknown.
Cell: "Astrocyte-Neuron Lactate Transport Is Required for Long-Term Memory Formation"
Akinobu Suzuki, Sarah A. Stern, Ozlem Bozdagi, George W. Huntley, Ruth H. Walker, Pierre J. Magistretti, Cristina M. Alberin