| Objective: To investigatethe influence of movement on extraction abilityof spatial memory of rats and the expression of Orexin-A, OX1 R at the cerebellum as well as providing neurobiological data for revealing the different and long period of exercise intervention’s influence on mechanisms of extraction ability of spatial memory of rats through the establishment of swimming exercise model of long-term and different load. Methods: Selecting 36 Sprague-Dawley(SD) male rats which were2-month- old and without specific pathogen, Then the rats were randomly divided into three groups: control group(group C, 10), moderate-load group(group M, 13),excessive-load group(group O, 13). First, each group of 8 days of Morris water maze test(7 days Place Navigation + 1 day Spatial Probe Test); and After that, the control group were feed freely for 8 weeks; The group M swam for 8 weeks with the moderate-load and the group O swam for 8 weeks with excessive-load. After the swimming-exercise intervention, one day for space exploration experiment to determine the effect of different exercise load on the extraction of spatial memory in rats. Kill the rats within a set time, and then detect the biochemical indicators. Thereafter decapitatedand determination levels of blood serum testosterone by application of ELISA technology; the Real time PCR was used to detect the expression of Orexin-A and OX1 R mRNA in the cerebellum; immuno-fluorescence was used to detect the distribution of Orexin-A、OX1R at the cerebellum and Western blot was used to detect the expression level of the protein. Results:(1) Weight monitoring results: the first and second weeks, the average weight of each rat had no difference between groups(P>0.05); after the third week, the weight of the group of group M and group O was less than the group of group C(P<0.01); after the fifth week, the weight of the group of group O was less than the group of group M(P<0.01);(2)Blood testosterone test results:the concentration of blood testosterone at the group M was significantly lower than that of group C(P<0.01), which at group O was significantly lower than that of group C and M(P<0.01).(3) Morris water maze experiment results: in the navigation experiments,there was difference about the average escape latency time among the three groups of rats. the time at the second day was significantly shorter than the first day(P<0.05,P<0.01), the time from third to seventh day was significantly shorter than the second day(P<0.05, P<0.01), and there has been no difference about the average escape latency time among them since the third day(P>0.05); in the space exploration experiments, before the exercise intervention, three groups of rats went into the water from four quadrant respectively; and there was no differences among groups(P>0.05);after the exercise intervention, the times that three groups of rats crossed the platformwere more than before the exercise intervention(P<0.05,P<0.01); the times that the group M crossed the platform were more than the group C(P<0.05)and he times that the group O crossed the platform were less than the group C.(4) The detection results of Real- time PCR : the expression of Orexin-A mRNA in the group M was higher than the group C(P<0.05) and the expression of Orexin-A mRNA in the group O was lower than the group C(P<0.05); the expression of OX1 R mRNA in the group M was lower than the group C(P<0.05) and the expression of OX1 R mRNA in the group O was lower than the group C(P<0.05).(5) The results of Western blot test: the protein expression of OX1 R in the group M was lower than the group C( P<0.05) and the protein expression of OX1 R in the group O was no differences with the group C(P>0.05).(6)The detection results of Immunofluorescence test:Orexin- A and OX1 R have extensive expressionin the cerebellum and Orexin-A express particularly in cerebellum Purkinje cells.the protein expression of Orexin-A in the group M was lower than the group C(P<0.05)and the protein expression of Orexin-A in the group O was no differences with the group C(P>0.05).(7) The results of correlation analysis on each index: There is significant positive correlation between the average number of the original platform and the expression level of Orexin-A mRNA in the cerebellum after exercise intervention(P<0.01), while which is significant negative correlation with the expression level of OX1 R mRNA(P<0.01) and the protein expression level of OX1R(P<0.05). Conclusion:(1) The long-term and moderate load exercise raised the expression of Orexin-A mRNA at the cerebellum as well as slowed attenuation speed of extraction ability of spatial memory of rats.(2) The long-term and excessive load movement lowered the expression of Orexin-A and OX1 R mRNA at the cerebellum accelerated the attenuation speed of extraction ability of spatial memory of rats, which play a negative role on the keeping spatial memory.The reason may be the excessive load movement has interference on translation of the Orexin-A and OX1 R mRNA properly, which needs to further research. |
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