Objectives The purpose of this study is to verify the phenytoin-resistant mesial temporal lobe epilepsy (MTLE) induced by Li-pilocarpine and screened by antiepilepsy drug (AEDs). Methods The rats with MTLE were induced by Li-pilocarpine, which were screened by effect of phenytoin treatment monitored by vedio-EEG. The living microdialysis technology was used for verification of drug concentration in brain of drug-resistant and drug-responsive rat model, and the P-glycoprotein expression was detected by immunohistochemical method. Results Sixteen rats with chronic MTLE were successfully induced in total 30 rats, among which, 6 drug-resistant rats with MTLE were screened. The brain/plasma ratio of area under the curve in drug-resistant rats was significantly lower than that of drug-responsive rats (0.15±0.03 vs. 0.28±0.05, P<0.05). In addition, the P-glycoprotein expression in brain of drug-responsive rats was obviously higher than that of drug-responsive rats (P<0.05). Conclusions The low concentration of phenytoin in drug-resistant rat model with MTLE was verified that might be related to the over-expressed P-glycoprotein in brain.
ObjectiveIn order to evaluate that whether the P-glycoprotein-inhibitor verapamil (VPM) could effect the distribution of antiepileptic drug phenytoin (PHT) in a rat model of mesial temporal lobe epilepsy (MTLE).MethodsThe rat models of MTLE were induced by li-pilocarpine and were randomly divided into two groups (PHT group and VPM+PHT treatment group) to compare the PHT distribution in brain, liver and kidney. Brain dialysate samples were collected by microdialysis technology. And the analysis of samples for PHT concentration was performed by high performance liquid chromatography (HPLC). The comparisons were carried out by t test (or Wilcoxon test).ResultsIn VPM+PHT treatment group, 4 out of 9 rats were dead within 30 minutes after drug administration. The significantly decreased area under the curve (AUC) ratio of brain/plasma in VPM+PHT group was 0.11±0.06 when compared with PHT group 0.21±0.02 (t=3.237, P=0.025), while there were no significant differences in ratios of liver/plasma ［PHT (1.12±0.37) vs. VPM+PHT (0.99±0.27), Z=−0.490, P=0.624］ and kidney/plasma ［PHT (0.74±0.16) vs. VPM+PHT (0.49±0.26), t=1.872, P=0.103］ between two groups.ConclusionsThe P-glycoprotein-inhibitor VPM significantly decreased PHT level in brain of rat with MTLE.