Study On Changes Of Memory And Behavior After +Gz Exposure In Rats

Modern high-performance aircraft have good maneuverability. The positive acceleration produced by aircraft can reach +9Gz, lasting for 15s to 45s. This may exceed physiological tolerance of human beings. The increased rate of +Gz-induced loss of consciousness (G-LOC) was so great that G-LOC had become the main factor threaten flying safety. In order to improve the endurance ability of+Gz, pilots were subjected to high G simulated training with the human centrifuge, and experience of G-LOC were suggested to be used as one training item. However, whether repeated high G exposure can injure the health of pilots and produce cumulative effect? Whether repeated low G exposure can protect pilots from injury caused by later high G exposure? Since there is no report about the effect of+Gz on memory and behavior, it is important to clarify these problems for guiding +Gz training of pilots and ensuring flying safety. As one of the advanced function of brain, learning and memory can be decreased by brain ischemia. Cerebral blood flow is decreased significantly during high +Gz exposure, and this may also induce the decreasing of learning and memory. The purpose of this study is to explorechanges of memory and behavior under different +Gz exposure level, and validate correlation between +Gz exposure level and changes of memory and behavior, and to clarify whether repeated low +Gz exposures before high +Gz exposure could provide protective effect on rats' brain.Male SD rats were exposed to +Gz on animal centrifuge (offered by animal experiment center of the Fourth Military Medical University), then changes of memory and behavior were observed at the time of immediately, 6h, Id, 2d, 4d, 6d after different +Gz exposure with Y-maze test, Step-through test, Open field test and balance test.The main findings are as follows:1. Effect of different +Gz exposure on rat's memory and behaviorTo investigate the effect of different +Gz exposure on rat's memory and behavior. We found that: as compared with control, there is no effect on rat's memory and balance function after +6Gz/3min exposure, only number of rearing decreased significantly at the time of immediately and 2d after +6Gz/3min exposure. As compared with control, time of reaction prolonged significantly at the time of immediately and 2d after +10Gz/3min exposure; number of rearing and number of crossing decreased significantly at the time of immediately and 2d after -t-10Gz/3min exposure; balance function decreased significantly at the time of immediately after +10Gz/3min exposure. As compared with control, percentage of right reflex decreased significantly and time of reaction lengthened significantly at the time of immediately > Id* 2d, 4d and 6d after +10Gz/5min exposure; time stay in center grille lengthened significantly at the time of immediately after +10Gz/5min exposure; number of rearing and number of crossing decreased significantly at the time of immediately and 2d after +10Gz/5min exposure; balance function decreasedsignificantly at the time of immediately and 2d after +10Gz/5min exposure. As compared with +10Gz/3min, percentage of right reflex decreased significantly and time of reaction lengthened significantly at the time of Id-* 2d^ 4d and 6d after +10Gz/5min exposure; time stay in center grille lengthened significantly at the time of immediately after +10Gz/5min exposure; balance function decreased significantly at the time of immediately and 2d after +10Gz/5min exposure. It is suggested that +6Gz/3min exposure did not change rats' memory and behavior obviously, while +10Gz/3min exposure may induce provisional disturbance in memory and changes in behavior in rats, and +10Gz/5min exposure may induce serious sustained disturbance in memory and obvious changes in behavior in rats.2. Effect of repeated +10Gz/30s exposures on rat's memory and behaviorTo investigate the effect of repeated +10Gz/30s exposure on rat's memory and behavior. We found that: as compared with control, whether exposed to repeated +10Gz/30s for one day or repeated...