Through test, Y maze test the impact of the mechanism of memory in rats

Ø Summary

OBJECTIVE : To investigate the mechanism of the effect of darkness test and Y-maze test on memory function in rats.

Method: 24 male SD rats were randomly divided into control group, + 10 Gz group and the push-pull 3 groups, 8 rats. Changes in memory function of rats at different times after treatment were recorded. Results: Sliding avoidance test group the number of errors and the error time after exposure compared with the control group increased significantly [6 h respectively (3. 3 ± 1.0), ( 2.3 ± 0.6) s, vs (0. 0 ± 0.0), (0.0 ± 0.0) s; 6 d , respectively (0.3 ± 0.5), (1. 3 ± 0.9) s, vs (0 3 ± 0.5.), (0.1 ± 0.2) s, (P <0.01) ], more The +10Gz group also increased significantly ; the incubation period was significantly shorter after the exposure than the control group (P<0.01) . Sliding maze test accuracy group immediately after the exposure was (82.5 ± 4.6)%, 2 d was (75.0 ± 16.0)%, respectively, compared with the control group (92. 5 ± 4.6)%, (100.0 ± 0 0)% Significantly lower (P < 0.01) . When the reaction was immediately after exposure (33.6 ± 12. 9) s, 2 d was (67.4 ± 32.9) s, and with the control group compared to + 10 Gz group was significantly prolonged (P <0.01). Conclusion : + 10Gz exposure for 3 min after push-pull action can lead to severe persistent memory dysfunction in rats.

Keywords : acceleration , push-pull action , push-pull effect , memory

Ø Objects and methods

1.1 Experimental animals and grouping

24 male SD rats (Experimental Animal Center of the University), body weight (185 ± 10) g, the reclaim for 1 week before the experiment and allowed to adapt to the environment, excluding the impact shock, and other environmental factors on memory and behavior in rats . The rats were randomly divided into control group, +10 Gz group and push group 3 groups of 8 animals.

Ø animal behavior test method

1.2.1 Animal exposure methods

The animal centrifuge was used to simulate +Gz with a radius of 2 m . The rat was fixed horizontally on the arm of the centrifuge , and the head of the rat was oriented toward the axis of rotation of the centrifuge. The push-pull group was exposed to -1Gz for 1 min, followed by +10 Gz exposure , and the peak action time was 3 min . The +10Gz group only exposed +10Gz , the peak action time was also 3 min, and the acceleration growth rate was 1 G · s- 1 . The control group was only placed in a plexiglass box for 3 min, but no +Gz exposure.

1.2.2 Avoiding dark experiment

It is learned that the rats stay in the bright box for more than 5 minutes . After the study, the number of errors, error time and latency of the rats were recorded within 5 minutes . The timing of learning and memory measurements is the same as the Y- type labyrinth experiment.

1.2.3 Y- type labyrinth experiment

Animal 10 times 9 times (90%) the reaction is determined to be positive Institute Standards. 24 h after Exposure to + Gz, and to immediately after the end of exposure, 6 h, the changed 1 d, 2 d, 4 d and 6 d and accuracy required to accomplish this 10 reaction of rats were detected, per The test was carried out 10 times. Experiment time is 8 hours a day: 00 ~ 12: 00 (6 h exposure to 3 points in the afternoon of the day: 00 to 5:00), in the same under similar environmental conditions. 1.3 Statistical analysis All data were expressed as mean ± standard deviation . The random unit group analysis of variance was performed using " SPSS 10. 0 FOR WINDOWS " , and the t test was used for comparison between the two groups .

Ø Results

2.1 avoidance rats change the number of errors, and time latency error experiments can be seen from Table 1, the number of errors and error control rats with baseline time increases measurement times as compared to no significant change; + 10 Gz the number of errors and the error time rats increased significantly compared to baseline values only in the exposed 6h (P <0. 01), compared to control group there was significant difference (P <0. 01); the number of errors sliding group of rats The error time was significantly higher than the baseline value at 6 h and 6 d after exposure (P < 0.01), and also significantly increased compared with the control group and the + 10 Gz group (P < 0.01) . No latency control rats compared to baseline values measured with increasing number of significant changes; + 10 Gz latency of rats did not change significantly after exposure, compared with the control group at all time points no significant differences; latency of rats in a push-pull The baseline values ​​were significantly shorter at 6 h , 2 d , 4 d, and 6 d after exposure (P < 0.01), which was significantly shorter than the control group and the + 10 Gz group (P < 0.01) .

2.2 The correct rate of the labyrinth experiment in each group and the change of the reaction time The correct rate of the control rats increased with the increase of the number of measurements and then increased (P<0.01). The rats in the 10 Gz group were correct. 2 d and immediately when the correct sliding of rats exposed group; rate immediately after exposure when the value of 2 d was significantly decreased compared to baseline (P <0. 01), at each time point compared with control rats significant differences were not The baseline value was significantly lower (P < 0.01), which was also significantly lower than that of the control group (P < 0.01) . The rats in the control group gradually decreased with the increase of the number of measurements compared with the baseline value (P<0.01). The rats in the +10 Gz group significantly prolonged the baseline value immediately after exposure and 2 days (P<0). 05), significantly longer than the control group (P <0. 01); immediately after the reaction when exposed sliding rats, baseline values were significantly longer (P <0. 05) when compared to 2 d and 4 d, and also Significantly longer than the control group and the + 10 Gz group (P < 0.05, P < 0.01,) .

Ø Discussion

In recent years , fighters have been increasing their push-pull action during maneuvering. According to reports, the United States from 1982 to 1996 plane crash and death of people or the severe G - LOC accidents, there is a big possibility the top 12 accident sliding movement of 5% and 29% had possible push-pull action, stunt pilot experienced G -. The LOC have 47% is clearly related to the push-pull effect. In the past, people considered - Gz 's low endurance , there is no special anti-load equipment on the aircraft , so the pilot should be asked to avoid doing - Gz action. Modern tactics require fighters to attack each other with rapid action , and in order to reduce the chance of radar discovery , push-pull actions often occur in actual flight. Learning and memory are important brain functions essential for animals and human beings to survive . They are interrelated neural processes and external manifestations of nervous system activities , which can reflect the functional state of the nervous system. For humans, it is also the basis for intellectual activity, learning refers to the new behavior (experience) acquisition and development, and to maintain and reproduce the experience acquired through learning, which is the memory. The Y- maze experiment is a method for detecting the ability of the visual and spatial position of rats to judge and recognize. The experimental results show that, + 10 Gz group rats exposed than the control group was significantly longer reaction time and immediately after 2 d, and at other points of time and the control group before their exposure as compared to no significant difference. From + Start time 1 d after Gz exposure, sliding rats effects than + 10 Gz group and control group was significantly longer, and the correct rate than + 10 Gz group and the control group was significantly decreased, has not been restored to normal until 4 d, the Tip sliding operation after exposure + 10 Gz memory is significantly reduced in rats 3 min continuous, the most significant decrease in the time of such 2d.

In the avoidance test (refer to ), the number of errors and the group of rats sliding the wrong time and the time of exposure than the control group, and 6 d + 10 Gz group increased significantly after 6 h, the latency after exposure 6 h, 2 d , 4 d and 6 d were significantly shorter than the control group and the + 10 Gz group ; while the number of errors and error time in the + 10 Gz group were significantly increased compared with the control group at 6 h after exposure , and the incubation period was compared with the control group. There is no significant difference than the ratio. This indicates that the push-pull effect aggravates the effect of + Gz exposure on memory function in rats. Centrifuge test confirmed that a large number of push-pull operation can thereafter decreased endurance + Gz, slow heart rate, arterial blood pressure, impedance base, and total peripheral resistance decreased reflection adjustment, increasing stroke volume and the like. Analysis of the reasons, probably in - when 1 Gz, the inertia of blood to the head shift, a sharp rise in blood pressure caused by carotid artery carotid sinus and aortic arch baroreceptor reflex strong, the cardiac vagal activity increased central sympathetic central inhibition The heartbeat is slowed down , the cardiac output is greatly reduced , and the total peripheral resistance is reduced , resulting in a decrease in heart level blood pressure. - After the end of 1 Gz , the above effects did not resolve immediately , so at the subsequent + 10 Gz effect , the head level blood pressure was more severe than the decrease without the pre --1 Gz effect. At the same time, because the central activity of the heart is still strong , the sympathetic center is still in a state of inhibition , and the baroreceptor of the carotid sinus area is affected by the reflex response of hypotension at this time. - 1 Gz not only the head followed by + 10 Gz levels of blood pressure decreased more, but also damages the body's compensatory response of + Gz, resulting in + restore cardiovascular function than when 10 Gz - significantly deteriorated when 1 Gz, so that Ischemia and hypoxia in rat brain tissue is more serious , and even leads to ischemic changes of brain tissue neurons.

In conclusion , this study showed that + 10 Gz exposure for 3 min can cause transient memory dysfunction in rats , and + 10 Gz exposure for 3 min after push-pull action causes persistent and severe memory dysfunction in rats , indicating push-pull effect. The effect of + Gz exposure on memory function in rats was aggravated .