Effects of simulated environment of space flight on learning and memory performance in the Morris water maze test in rats

Abstract

Objective To investigate the learning and memory abilities of rats in the Morris water maze(MWM) test under the different simulated environment of space flight. Methods Forty-eight SD rats were randomly divided into Sham group, TS group and TS+ I group, with sixteen animals in each group. Place navigation, spatial probe and working memory tests were performed to determine the learning and memory abilities for each group after 2 weeks and 4 weeks respectively. The Sham group served as controls. Results In the place navigation test after simulated 2 weeks, the latency was the longest ((59.63±3.55)s) in the rats of TS+ I group, shorter ((38.02±3.21)s) in the TS group, the shortest ((20.85±3.22)s) in the Sham group. Results after simulated 4 weeks were similar to the results after simulated 2 weeks to rats. In the spatial probe test in the MWM test after simulated 2 weeks, the ratio of time spent in target quadrant was the least (0.29±0.04) in the rats in the TS+ I group, more (0.38±0.03) in the TS group, and the most (0.42±0.03) in the TS+ I group. In the working memory test in the MWM test, after simulated 2 weeks, compared with the Sham group ((23.05±7.39)s), the latency was longer in the TS group ((41.01±6.74)s) and TS+ I group ((60.05±11.61)s). All these differences were significant(P<0.05, P<0.01). Conclusion More serious cognitive impairment will occur in the tail suspension plus isolation rather than the single tail suspension in rats. Key words: Simulated environment of space flight; Morris water maze; Learning and memory