Study On Functional Recovery In Rats With Cerebral Ischemia At Different Times

Cerebral ischemia is considered as a serious threat to the human health for thehigh incidence, high morbidity and high mortality. Cerebral ischemia rat model is animportant way to research injuries caused by cerebral ischemia. It has an importantmeaning for the early diagnosis and treatment of the disease, by using the model tostudy the mechanism and the recovery of brain injury.The rat model of cerebral ischemia was established by middle cerebral arteryocclusion (MCAO) in the left hemisphere. Test plan was designed in the way of fivegroups. From four aspects: gait, electroencephalogram(EEG), Magnetic ResonanceImaging (MRI) and histopathology, the recovery state of cerebral ischemia rats wereanalyzed and the sensitive experimental parameters were extracted. Specific researchcontents include:1、GaitThe front and hind paws of4H,24H group and control group were painted withdifferent colors. Rats were allowed to walk freely, gait parameters were measured.4hours after the surgery, rats were rotating to the right side. The gait parameters hadsignificant difference compared with the control group. Almost all the rats whichoperated after24hours, were back to normal. Compared to the control group, therewas no significant difference of the gait parameters.2、EEG’s acquisition and analysisSomatosensory evoked potentials (SEP) of left cortex was detected byelectrically stimulating the right median nerve of rat paw. The EEG in resting statewas analyzed by spectral technology. SEP and power spectral change process in theleft side of the primary somatosensory cortex after arterial ischemia werequantitatively assessed. Compared with four experimental groups and control group,the SEP result shows that, the latency of SEP is significantly prolonged, while theamplitude is decreased. And the energy of θ wave, wave, β wave, γ waveare significantly smaller. With the extension of time after operation, the difference ofthese characteristics between control group and ischemia group has been reducedgradually.3、Brain magnetic resonance imaging (MRI)Through the magnetic resonance imaging (MRI) test, the changes of ADC ((Penumbra-Normal area)/Normal area,(Penumbra-Normal area)/Focal zone))and MRS ((Naa-Cho)/Cr) in different periods after cerebral ischemia were observed.(Focal zone-Normal area)/Normal area) remains in a relatively stable state in group4H,24H and1W data, however,((Penumbra-Normal area)/Normal area),((Penumbra-Normal area)/Focal zone) decrease with the postoperative time andthese datas are different.((Naa-Cho)/Cr) from focal zone in MRS in a relatively stablestate in different group,((Naa-Cho)/Cr) form penumbra changes significantly in4h,24h and1w group.4、HistopathologyBrain tissue was tested through transmission electron microscope, the contents ofGAP-43and synapses protein were tested through Western Blot test. Under theelectron microscope, neurons of rats were abnormal significantly after1W, thenumber of synaptic decreased significantly; GAP-43increases significantly. GAP-43peaks after2W, then reduces.The change of Syn is not obvious..By analyzing the experiment results, rats have a certain recovery function,however, this kind of resilience has a certain extent. The scope of the recovery hascertain restriction, only penumbra has the ability to recover. At the same time, there isa link among the behavior change, EEG, Magnetic resonance imaging andhistopathology. SEP can reflect the change of brain cortex function in rat model ofcerebral ischemia to some extent. SEP has the advantage in the prevention of cerebralinfarction.