全蝎乙醇提取物对耐药惊厥大鼠脑内mdr1 mRNA和P-gp表达的影响

Influence of scorpion alcoholic extraction on mdr1 mRNA and P-gp expression in brain of phenytoin-resistant convulsive rats

目的:研究全蝎乙醇提取物(scorpion alcohol extraction,SAE)对电刺激大脑皮层点燃耐苯妥英钠大鼠惊厥模型的对抗作用,并探讨其抗耐药作用机制。方法:采用大鼠大脑皮层运动区定位放置微电极并反复电刺激此区域点燃同时灌胃苯妥英钠(PHT,0.154 g.kg-1.d-1)7 d的方法,建立耐苯妥英钠大鼠惊厥模型。实验共设6组,分别为正常组、惊厥模型组(CMCG)、耐苯妥英钠惊厥模型组(PRCG)、维拉帕米(0.038 5 g.kg-1)阳性药组(VPCG)、全蝎乙醇提取物低剂量组(SAE1,6.5 g.kg-1)和全蝎乙醇提取物高剂量组(SAE2,13.0 g.kg-1)。给药后观察全蝎乙醇提取物对耐药大鼠惊厥阈值和发作程度的影响。采用逆转录聚合酶链反应(RT-PCR)技术,检测脑内mdr1mRNA的表达变化;采用免疫组化(SABC法)技术,检测脑内P糖蛋白(P-glucoprotein,P-gp)的表达变化。结果:全蝎乙醇提取物2种剂量及维拉帕米,均可使耐苯妥英钠大鼠惊厥阈值(480.38±18.48)μA明显升高,与惊厥模型组和耐苯妥英钠惊厥模型组相比均有显著性差异(P<0.01)。给予苯妥英钠后,耐药模型组mdr1 mRNA和P-gp表达量均较惊厥模型组继续增高;全蝎乙醇提取物高、低剂量以及维拉帕米使mdr1 mRNA和P-gp表达量减少(均P<0.01)。结论:全蝎乙醇提取物对耐苯妥英钠大鼠惊厥模型产生明显的对抗作用。其抗耐药机制与抑制耐药惊厥大鼠脑内mdr1 mRNA表达和相应减少其表达产物P-gp有关。

Objective： To study the anticonvulsive action of scorpion alcoholic extraction （SAE） on phenytoin-resistant convulsive rats made by direct cortical electrical stimulation in order to investigate the mechanism of antagonizing drug-resistance of SAE. Method： Using the method of implanting microelectrodes in the cortical motor area of the brains of rats where the brain tissue was stimulated frequently by electricity through microelectrodes until igniting and then PHT （0.154 g·kg-1·d-1） ig for 7 days, We established phenytoin-resistant convulsive rat model. Total 6 groups were set up in the experiment： Normal control group, convulsion model control group （CMCG）, phenytoin-resistant convulsion control group （PRCG）, verapamil positive control group （VPCG, 0.038 5 g·kg-1）, scorpion alcohol extraction （SAE1, 6.5 g·kg-1） and scorpion alcohol extraction （SAE2, 13.0 g·kg-1）. After ig both doses of SAE （6.5, 13.0 g·kg-1）, the effects of SAE on the changes of convulsion threshold of phenytoin-resistant convulsive rats were observed. The method of RT-polymerase chain reaction （RT-PCR） was used to detect the changes of mdr1 gene expression and the method of immunohistochemistry （SABC） was adopted to determine the changes of P-gp expression. Result： Both doses of SAE and verapamil （Ver） ig all raised the convulsant threshold of phenytoin-resistant rats （480.38±18.48） μA, there were statistical differences （P〈0.05） compared to themselves before drugs-treated. PHT was administrated, and mdr1 mRNA and P-gp expression in PRCG was much higher than that in CMCG, with significantly statistical difference （P〈0.01）; ig both doses of SAE and Ver all decreased mdr1 mRNA and P-gp expression compared to PRCG respectively （P〈0.01 ）. Conclusion： SAE and Ver ig all produce antagonizing action on phenytoin-resistant convulsive rat model. The machanism is related with inhabiting the mdr1 mRNA expression and further decreasing the product P-gp.