Brain glycogen depletion following prolong exercise in rats

 

Takashi Matsui

Laboratory of Exercise Biochemistry, University of Tsukuba Graduate School of Comprehensive Human Sciences, Japan

 

Some brain loci utilize glucose as an energy source during exercise. On the other hand, brain glycogen is increasingly understood to be an important factor in brain energy metabolism. However, it is uncertain whether glycogen is utilized as an energy source in the brain during exercise. This is because brain glycogen is rapidly depleted by activation of glycogenolysis enzymes under the hypoxic-ischemic conditions that occur after animals are killed. Therefore, in our present study, by using a high-energy focused microwave irradiation (MI) method which can momentarily inactivate glycogenolysis enzymes, we tried to accurately measure the changes in brain glycogen during exercise. Rats were subjected to running at 20 m/min for 2 hours. Nine brain loci were collected following MI fixation immediately after cessation of exercise and were used for determination of glycogen. Glycogen levels in the cortex, hippocampus, hypothalamus, cerebellum, and medulla oblongata decreased more than 50 % with exercise. On the other hand, glycogen levels in the septum, striatum, thalamus, and midbrain were not significantly reduced by exercise. These results suggest that glycogen in some brain loci may serve as an energy store during prolonged exercise.

 

Key words: Exercise, Brain, Glycogen