| Objective：With the implementation of the new military flight training program, the strength anddensity of flight training with characteristics of long-time, high-load and high-intensitywill increase. That is the reason why the flight crews are prone to complex fatigue whichincludes physical and mental fatigue, especially in modern warfare. The complex fatiguenot only affects the efficiency of the flight staff, but induces a variety of diseases and evenleads to flight accidents. As the basic abilities of our life, the decline of thelearning-memory abilities will seriously affect our daily work and life, especially military action. Previous clinical and experimental studies have confirmed the certain influence ofexercise-induced fatigue on learning and memory abilities in humans and experimentalanimals. However, the mechanism of complex fatigue influencing the learning andmemory abilities has not been fully understood, which still needs further research.Therefore, investigating the concrete mechanism of the effects of complex fatigue on thelearning and memory abilities has great significance in the guidance of preventing andintervening the adverse effects of complex fatigue.Methods：According to the relevant literature and previous studies, we established the animalmodel of complex fatigue by keeping the rats in a squirrel cage filled with water, whichwas2.2cm in depth, for5days, and the swimming time was used to evaluate the degreeof fatigue in rats. All the animals were subjected to Morris Water Maze (MWM) to test themean escape latency and percentage of time spent in the target quadrant, in order to assessthe learning and memory abilities. Westen Blot was applied to examine the level of cyclicAMP responsive element binding protein (p-CREB) phosphrylationin hippocampus, inorder to study the molecular mechanisms of learning and memory abilities. The activity ofthe antioxidant enzymes, including the Superoxide dismutase (SOD), the glutathioneperoxidase(GSH-Px) and the Malonaldehyde (MDA) in rat serum, were analyzed toclarify the cause of the changes in antioxidant enzymes metabolism in complex fatiguerats.Results：1. On the fifth day of the experiments, the body weight of the experimental rats andfood-restricted rats was significantly reduced, but there was no significant differencebetween the two groups. Compared with the food-restricted and control rats, theswimming time of the complex fatigue rats was significantly decreased.2. As shown in the results of Morris water maze navigation test, compared with thecontrol and food-restricted rats, the escape latency of complex fatigue rats from the second day to the forth day was gradually prolonged, suggesting that the decline of the learningability in the experimental rats might be ascribed to the complex fatigue. And the results ofthe spatial probe test showed that the rats in the complex fatigue group spent less time inthe platform quadrant time than that in control and food-restricted groups, indicating thatthe reduced platform quadrant time in the experimental animals might be ascribed tofatigue.3. Western blotting was used to observe the protein expression of p-CREB in thehippocampal region of the experimental animal. Results showed that relative content ofp-CREB in hippocampus of the complex fatigue rats was decreased than the control andfood-restricted rats.4. As shown in the results of antioxidant capacity test, compared with the control andfood-restricted rats, the serum MDA content in the complex fatigue rats was increased,and the expression of the serum superoxide dismutase (SOD) and glutathione-peroxidase(GSH-Px) of the experimental rats was increased as a result of complex fatigue.Conclusion：1. We successfully established the complex fatigue rat model by keeping the rats in asquirrel cage filled with water, which was2.2cm in depth, for5days, and the swimmingtime used as an indicator of the degree of fatigue is objective and accurate. By adding afood-restricted group, the effects of body weight loss in the complex fatigue rats could beexcluded.2. The impairment of spatial learning and memory ability in complex fatigue animalsmay be associated with the decreased level of p-CREB in hippocampus.3. When the body suffers from complex fatigue, the degree of lipid peroxidation andantioxidant capacity in rats are both significantly increased. The results imply that theantioxidant system is mobilized to eliminate the excessive free radicals in the complexfatigue rats. It is important to enhance the antioxidant capacity toprevent and recover fromfatigue. |
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