| ObjectiveTo observe the therapeutic effects and changes of the P-glycoprotein(P-gp) expression in different cerebral areas of the model rats of refractory epilepsy after low frequency repetitive transcranial magnetic stimulation(rTMS).MethodsForty-eight Wistar rats were injected by Kainic acid(KA) using a stereotaxic apparatus to establish the refractory epilepsy model. Rats of epilepsy model were randomly subdivided into seven groups: two refractory epilepsy model groups, including two different periods. two magnetic stimulation groups, a valproate acid group and a therapeutic alliance group, another 12 rats injected by sodium chloride as the control group. Give the rTMS with 0.3Hz every day, which contained 500 pulses and the stimulation intensity was 0.8T, continued for 14 days. Seizure frequency and electroencephalogram(EEG), before and after rTMS treatment, were collected for calculation, compared the spike numbers using the software running on MATLAB 6.5. Then the rats were sacrificed at definite time points. The Nissl and HE staining were performed on brain samples. The expressions of glial fibrillary acid protein and P-gp in cerebral were detected immunohistochemically.ResultsRats of magnetic stimulation group given at two weeks after KA injected showed a reduction in level of seizure frequency with significant difference when compared with those of the model group(P<0.05). In EEG recording, we can detect paroxysmal spikes occurred frequently in the CA3 area of hippocampus after two weeks of KA injected. When analysed by the program on MATLAB 6.5, compared with the model group, the numbers and overall duration of spikes were significantly decreased in the magnetic stimulation group given after KA injected, the valproate acid group and the therapeutic alliance group(P<0.05). When EEG signals analysed using linear dynamics, we found that the overall power spectrum decreased in the magnetic stimulation group given after KA injected, and the therapeutic alliance group showed a significant decreased compared with the model group(P<0.05). But the overall power spectrum increased in the valprote acid group. HE staining in rats of model group showed a obvious histopathological change in ipsilateral CA3 area, which exhibited severe cell degeneration and necrosis, gliosis reactived and hippocampal sclerosis, with numberous lymphocyte existing around. The astrocyte reactive showed a significant decrease in those of magnetic stimulation groups(P<0.05). Nissl dyeing displayed that the number of the neuron cell in ipsilateral CA3 area declined in model group, but improved in the magnetic stimulation groups.Immunohistochemistry of P-gp: The rats of magnetic stimulation groups showed a reduction of the P-gp expression level in the periform cortex and thalamus with significant difference compared with those of the model groups(P<0.05). Rats of valproate acid group showed a significant increase in level of P-gp in the CA3 area of hippocampus, periform cortex and thalamus compared with the therapeutic alliance group(P<0.05).Conclusion1 Low frequency rTMS can reduce the seizure frequency of refractory epilepsy and the number and duration of spikes. It can protect the neuron in hippocampus, control the astrocyte reactive and mitigate the hippocampal sclerosis.2 Low frequency rTMS dose not cause the overexpression of P-gp, however, it can reduce the overexpression of P-gp in cerebral of rats with refractory epilepsy whether caused by seizure or valproate acid.3 The analysis of EEG signals based on MATLAB 6.5 can effectively reduce the accurate information, and can distinguish the spikes from the background waves effectively and correctly.
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