The Influence Of Cerebral Ischemic Preconditioning On The Trigeminal Evoked Potential Of Ischemia-reperfusion Rat

Objective: To compare the characteristic of trigeminal evoked potential(TEP) with that of ischiadical evoked potential(IEP) for normal Wistar rat and investigate the influence of cerebral ischemic preconditioning(CIP) on TEP of ischemia-reperfusion rat. Methods: TEPs and lEPs were detected from 30 normal Wistar rats by giving electric stimulation and the characteristic of those compared. Then the animal model of focal cerebral ischemia-reperfusion was established by occluding middle cerebral artery with suture, 40 Wistar rats were randomly divided into four groups: sham-operated group (So, n=10), received operation without cerebral ischemia;,Preconditioning only group(Po> n=10), 15min cerebral ischemia only; Ischemic preconditioning group(Ip> n=10), 15 min cerebral ischemia and 2d reperfusion followed by cerebral ischemia 2h; Cerebral ischemia group(Ci> n=10), operation only and after 2d followed by cerebral ischemia 2h. After Id from last ischemia-reperfusion, TEPs were detected, brain taken out for HE staining. Results: TEP were detected from 30 rats, IEP from 20. The basic waveform of TEP was N1-P-N2 type, IEP was N-P type, but there was P'-N'type interference wave before N. The latencies of N1 , P in TEP were shorter than those of N, P in IEP, the amplitudes of N1-P were bigger than those of N-P, there was significant difference, P < 0.001; there was no significant difference in the coefficient variation oflatencies between TEP and IEP, the amplitudes's coefficient variation of Nj-P were significantly smaller than those of N-P. There were no significant difference in the latencies of N1,. P and the amplitudes of N-P between So and Po, P>0.05; the latencies of N1, P were prolonged, amplitudes of N(-P decreased in Ip and Ci compared with those in So, there were significant difference, P < 0.01; the latencies of N1 , P in Ip were shorter than those in Ci and the amplitude of N1-P in Ip were bigger than those in Ci, there were significant difference, P < 0.05. HE staining showed there were no significant ischemia necrotic neurons in Po and So, the ischemic and infarct volume in Ip were significantly reduced than those in Ci. Conclusion: The waveform of TEP is more stabile, there is no interference wave, its duplication, sensitivity better, the method of its detection more convenient, compared with IEP. CIP could alleviate prolongation of N1, P latency and decrement of Nj-P amplitude, could alleviate the injury of ischemia-reperfusion; the changes of TEP are basically identical to those of pathology, TEP is objective control standard to CIP.