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Enduring exercise and making memories
Glucose stored in brain cells is converted into lactate to maintain the brain during endurance exercise.
Glucose is stored as glycogen in muscles and fuels them through long bouts of exercise. Glycogen is also stored in astrocytes, glial cells found in the brain and spinal cord, and provides lactate to power functions such as memory formation, but little is known about its role in the brain during exercise.
A team led by researchers from the University of Tsukuba studied the metabolism in the brain and muscles of rats exhausted by a long trudge on the treadmill. They found that glycogen and lactate was almost depleted in their muscles, whereas brain glycogen only decreased by around two-thirds, and lactate levels increased.
The team found that lactate produced in the brain maintains levels of ATP — the body’s main energy molecule — and therefore fortifies the brain’s endurance. This finding could help explain the positive relationship between endurance and memory.
- PNAS 114, 6358–6363 (2017). doi: 10.1073/pnas.1702739114