Effect Of Stimulated ?₂ Receptor On Excitatory Amino Acids In The Brain Of Dementia Rats And Discussion On Its Mechanism

Objective:To explore the level of excitatory amino acid in the brain of dementia rats after exciting?2 receptor and discuss its mechanism.Methods:30 clean grade old male with obvious cognitive impairment SD rats aged over 24 months,with a body weight of about 650-750g were selected by morris water maze experiment and divided into 3 groups?n=10?according to random number table method.The first group was selected as the control group without any treatment?group C?.The second group was intraperitoneal injected with a small-dose?1ug/kg?of dexmedetomidine?group DEX₁?.And the third group was intraperitoneal injected with high-dose dexmedetomidine at 8ug/kg?group DEX₂?.After grouping,all of these rats were put back to their original feeding environment and fed for another 4 weeks meanwhile the above treatment were given.Then,the following operations were performed on the three groups of rats and the results were observed and recorded:?1?Morris water maze test.During the test,the escape latency of the three groups of rats?the time it took for the rats to find the migrated platform after entering the water?and the total path length?the total length of the rats swimming path from entering into the water to climb up migrated platform?were observed and recorded.?2?After the morris water maze test,5 rats in each group were sacrificed and the hippocampal tissues were taken out for HE staining,and the pathological changes in the CA1 area of the hippocampus were observed under the microscope.?3?Another five rats were selected from the three groups,and the expression levels of glutamic acid in the hippocampus were analyzed by liquid-mass method.Statistical analysis was performed to evaluate the differences among the three groups of rats.SPSS 17.0 software was used for analysis,and P<0.05 showed that the difference was statistically significant.Results:There were a total of 30 rats in this study,including 10 rats in the control group,10 rats in the low-dose dexmedetomidine group and 10 rats in the high-dose dexmedetomidine group.Statistical analysis results are shown as follows:1.Morris water maze test,Compared with Group C,the evasive incubation period on the 5th day was shorter in Group DEX₁?P<0.05?;and from 2nd to 5th day in Group DEX2?P<0.05?.There were no statistically significant between Group DEX₁ and Group DEX₂?P>0.05?,although the evasive incubation period was shorter at each time point in the later.Compared with Group C,the total path length of Group DEX₁ were shorter on the 3rd and 5th day?P<0.05?,and were shorter from the 2nd to 5th day in Group DEX₂?P<0.05?.Compared with the group DEX₁,the total path length at each time point in the group DEX₂ were shorter,but there were no differences between its?P>0.05?.2.HE staining:The number of cells in the hippocampus CA1 of Group C decreased,and were arranged disorderly in 1-2 layers.The cells in the hippocampus CA1 of Group DEX₁ and Group DEX₂ were slightly more orderly than those in Group C.3.The glutamic acid content in hippocampus:Compared with Group C,Group DEX₁ had reduced glutamic acid level,but there was no statistically difference?P>0.05?.But the more significantly reduced level were detected as to the Group DEX₂?P<0.01?.And the difference between Group DEX₁ and Group DEX₂ was also statistically significant?P<0.05?.Conclusions:?1?excitatory receptor can improve the spatial learning and memory ability of dementia rats and reduce the impairment of their cognitive function.?2?the results of HE staining in the CA1 area of the hippocampus of rats proved excite?₂receptor can reduce then damage of neurons.?3?.exciting the?₂ receptor can reduce the expression of excitatory amino acid Glu in the brain of the dementia rats and achieve the effect of brain protection.?4?the results of this experiment suggested that dexmedetomidine could improve the cognitive function of dementia,reduce the damage of neurons in the brain,and reduce the toxicity of excitatory amino acids,and its degree was correlated with the concentration of dexmedetomidine.