多药转运蛋白对癫痫大鼠脑内奥卡西平浓度的影响

目的 观察多药转运蛋白家族的成员P-糖蛋白(P-glycoprotein,PGP)和多药耐药蛋白(multi-drug re-sistance associated protein,MRP)对匹罗卡品慢性癫痫大鼠模型海马内神经元细胞外液中奥卡西平浓度的影响,证明奥卡西平是否为PGP和MRP的底物,探讨PGP和MRP参与难治疗性癫痫耐药的机制.方法 建立匹罗卡品慢性癫痫动物模型,将32只大鼠分为对照组、模型组、维拉帕米干预组、丙磺舒干预组(每组8只),于腹腔注射奥卡西平(80 mg/kg)后30、60、90、120、150 min,通过微透析及高效液相色谱技术,检测大鼠海马神经元细胞外液中的药物浓度.结果 维拉帕米干预后,癫痫大鼠海马细胞外液中奥卡丙平的浓度于给药后90～120 min(1.26±0.09、0.93±0.10)明显高于模型组(0.87±0.06、0.66 4±0.04),两组比较有统计学差异(P<0.05);丙磺舒干预后60～150 min,大鼠海马内细胞外液中奥卡两平的浓度(1.07±0.11、1.32±0.13、1.02±0.10、0.87±0.08)显著高于模型组(0.81±0.08、0.87±0.06、0.66±0.04、0.58±0.06)(P<0.05).结论 奥卡西平是PGP和MRP的底物,PGP和MRP能够选择性的将奥卡西平泵出血脑屏障外,降低癫痫病灶内的药物浓度,上述机制可能参与了难治性癫痫患者对奥卡西平产生耐药.     

维拉帕米对耐苯妥英钠和卡马西平癫(癎)模型大鼠电生理和行为的影响

目的 观察P-糖蛋白(PGP)拮抗剂维拉帕米对耐苯妥英钠(PHT)和卡马西平(CBZ)癫(癎)大鼠电生理指标和行为学的影响.方法 建立慢性杏仁核点燃癫(癎)大鼠模型,筛选出耐药组和治疗有效组,给予维拉帕米,观察其对各组大鼠后放电阈值(after discharge threshold,ADT)、后放电时程(after discharge duration,ADD)等电生理指标和行为学的影响.结果 相对于耐药对照组,耐药组大鼠在预先给予维拉帕米后,使用抗癫(癎)药物后ADT[(238.0±32.2)μA]明显高于耐药对照组[(177.0±23.3)μA,P＜0.05];ADD时程明显缩短,Racine行为分级明显下降(P＜0.05).结论 维拉帕米可以协助抗癫(癎)药物(AEDs)改善耐药大鼠的电生理活动,降低点燃后发作分级,提示有效抑制PGP有助于改善多药转运体高表达导致的癫(癎)耐药.     

P-糖蛋白对卡马西平和苯妥英钠通过大鼠血脑屏障影响的研究

目的观察P糖蛋白(Pglycoprotein,PGP)拮抗剂维拉帕米对卡马西平和苯妥英钠通过大鼠血脑屏障的影响,探讨PGP在难治性癫癎多药耐药机制中的作用。方法在健康大鼠大脑皮质内安置微透析探针,腹腔注射卡马西平(20mg/kg)和苯妥英钠(50mg/kg),在给药后不同时间点收集透析液,并用高效液相技术检测其中的药物浓度,通过微透析探针局部给予维拉帕米,观察后者能否提高大鼠皮质脑细胞外液中抗癫药物的浓度。结果维拉帕米升高了脑细胞外液中卡马西平[60min:(1.74±0.28)μg/ml,90min:(1.87±0.31)μg/ml]和苯妥英钠[30min:(1.08±0.30)μg/ml;60min:(1.54±0.22)μg/ml;150min:(0.91±0.19)μg/ml]的药物浓度,前者在给药后60～90min显著增高(P<0.05),后者在给药后30～150min显著增高(P<0.05)。结论PGP限制卡马西平和苯妥英钠顺利通过血脑屏障,降低脑皮质细胞外液抗癫癎药物浓度,难治性癫时PGP表达增加可能是引起患者对抗癫癎药物产生多药耐药的原因。     

拉莫三嗪及丙戊酸钠对锂-匹罗卡品致(癎)大鼠的神经保护作用及其对癫(癎)的治疗作用

目的:观察拉莫三嗪(LTG)及丙戊酸钠(VPA)对锂-匹罗卡品癫(癎)持续状态(SE)大鼠海马锥体细胞、齿状回门区神经元的保护作用及对癫(癎)的治疗作用.方法:用大鼠制作锂-匹罗卡品SE动物模型,分三组:SE对照组,LTG治疗组和VPA治疗组.此三组在SE后2h给予安定阻断(癎)性发作,再分别给予适量生理盐水(NS)、...     

普瑞巴林对慢性颞叶癫癎大鼠海马凋亡调控基因的影响

目的通过观察普瑞巴林对匹罗卡品慢性癫癎大鼠海马区Bcl-2和Bax表达的影响,探讨普瑞巴林治疗癫癎的药理学机制及对大鼠海马神经元的抗凋亡作用。方法采用氯化锂-匹罗卡品化学诱导方法建立慢性颞叶癫癎模型。经腹腔注射普瑞巴林40mg(/kg·d)连续治疗3周,免疫组织化学染色和Western blotting法检测不同处理组大鼠海马区Bcl-2和Bax表达变化。结果与生理盐水对照组比较,模型组大鼠海马区Bcl-2和Bax表达水平显著升高(均P=0.000);与模型组比较,普瑞巴林治疗组大鼠海马区Bcl-2表达水平升高、Bax表达水平降低,组间差异具有统计学意义(均P=0.000)。结论新型抗癫癎药物普瑞巴林可通过降低慢性颞叶癫癎大鼠海马区Bax表达、上调Bcl-2表达而抑制细胞凋亡,发挥神经元保护作用。     

锂-匹罗卡品癫(癎)模型中核转录因子的表达及干预机制

目的探讨癫发作时核转录因子(nuclear factor kappaB,NF-κB)在神经元损伤中的表达变化以及拉莫三嗪、黄芪注射液对这一过程的影响。方法干预组大鼠预处理3d后制作大鼠锂-匹罗卡品(lithi-um-pilocarpine,Li-PC)癫模型,造模后24h、3、7d应用光镜及电镜进行神经元形态学观察,利用免疫组织化学法半定量检测NF-κB的表达含量。结果与正常组比较,模型组海马内NF-κB表达明显增多(P<0.01),在24h达峰值;与模型组比较,拉莫三嗪、黄芪注射液能够使NF-κB表达增加(P<0.05)。结论NF-κB的主要作用是有利于神经元生存,拉莫三嗪、黄芪注射液可通过调控凋亡因子的表达而发挥对癫的神经元保护作用。     

锂-匹罗卡品致癎大鼠认知功能与海马苔藓纤维发芽和5-HT表达的变化

目的探讨癫癎发作后海马结构和海马5-羟色胺(5-HT)水平的变化,以及与认知功能改变的关系。方法采用锂-匹罗卡品复制大鼠癫癎模型,观察大鼠癫癎发作后大鼠海马组织结构、海马组织中5-HT水平的变化,并用Morris水迷宫观察大鼠认知功能的改变。结果 (1)大鼠癫癎发作后海马Timms染色显示苔藓纤维发芽(MFS)明显,半定量评分显示评分明显增高;(2)癫癎发作后海马5-HT免疫组织化学染色显示海马组织中5-HT神经元数量以及5-HT水平均明显减少;(3)癫癎发作后大鼠认知功能明显受到影响,大鼠寻找目标的潜伏期明显延长、游泳轨迹发生明显变化,以及规定时间内穿越平台次数减少。结论大鼠癫癎发作后认知功能明显下降,其原因可能与海马5-HT神经元数量以及5-HT水平的减少有关;癫癎的发作可能与海马苔藓纤维发芽有关。     

颞叶癫(癎)大鼠海马中miRNA表达谱的检测和分析

目的 探讨颞叶癫(癎)大鼠海马组织中miRNA分子表达谱的差异,为进一步研究相关miRNA在颞叶癫(癎)发病机制中的作用打下基础.方法 对同一父系和母系的子代大鼠,利用氯化锂-匹罗卡品化学诱导方法制备慢性颞叶癫(癎)大鼠模型.分别提取1只正常和3只颞叶癫(癎)大鼠海马组织的miRNA,采用高通量的miRNA微阵列芯片杂交,筛选颞叶癫(癎)海马组织中差异表达的内源性miRNA.结果 在大鼠海马组织中共检测到125个miRNA基因.与正常大鼠相比,颞叶癫(癎)大鼠海马组织中差异表达的miRNA有23个,其中有5个miRNA下调,18个miRNA上调.结论 与正常大鼠相比,颞叶癫(癎)大鼠海马组织中存在差异表达的miRNA分子,差异表达的miRNA分子可能参与癫(癎)的发病过程,具有潜在的研究价值.     

STAT3在匹罗卡品致(癎)大鼠星形胶质细胞增生中的作用

目的 探讨致(癎)状态下大鼠海马内信号转导与转录激活因子3(STA3)与星形胶质细胞增生的关系.方法 匹罗卡品(PILO)腹腔注射建立大鼠颞叶癫(癎)模型,免疫组织化学方法观察阻滞JAK/STAT通路前后大鼠海马p-STAT3与胶质纤维酸性蛋白(GFAP)阳性细胞的表达规律,双重免疫荧光方法观察p-STAT3与GFAP阳性细胞的关系.结果 癫(癎)发作3 h(SE 3 h)时即出现STAT3在海马内被激活,SE 3 d时达高峰,之后渐降低,至SE 30 d时仍维持在较正常时略高的水平上;GFAP阳性细胞数的变化规律与之类似.预先用AG490阻断STAT3通路后,海马区p-STAT3乃及GFAP阳性细胞数均明显减少.双重免疫荧光结果发现p-STAT3阳性胞核位于GFAP阳性细胞胞浆中.结论 匹罗卡品导致的癫(癎)伴有大鼠海马星形胶质细胞内STAT3的激活,STAT3的活化可能促进星形胶质细胞的反应性增生.     

MK-801对耐苯妥英钠和卡马西平癫(癎)大鼠模型脑表达P-糖蛋白的影响

癫(癎)是神经科仅次于脑血管意外的常见疾病,其中大约有30%的患者对多种抗癫(癎)药物表现耐药,癫(癎)发作得不到有效控制,被称之为难治性癫(癎).难治性癫(癎)患者对药物产生耐药的机制还不明确.研究表明癫(癎)病灶内高度表达P-糖蛋白(P-glycoprotein,PGP)[1],PGP是一种多药转运蛋白,能够分解ATP获能从而逆浓度梯度将抗癫(癎)药物转运出脑组织,减少了癫(癎)病灶内的药物浓度,降低了药物的疗效,上述机制可能参与了难治性癫(癎)患者对多种抗癫(癎)药物产生耐药.     

P-glycoprotein and multidrug resistance-associated protein are involved in the regulation of extracellular levels of the major antiepileptic drug carbamazepine in the brain.

Despite considerable advances in the pharmacotherapy of epilepsy, about 30% of epileptic patients are refractory to antiepileptic drugs (AEDs). In most cases, a patient who is resistant to one major AED is also refractory to other AEDs, although these drugs act by different mechanisms. The mechanisms that lead to drug resistance in epilepsy are not known. Recently, over-expression of multidrug transporters, such as P-glycoprotein (PGP) and multidrug resistance-associated protein (MRP), has been reported in surgically resected epileptogenic human brain tissue and suggested to contribute to the drug resistance of epilepsy. However, it is not known to what extent multidrug transporters such as PGP or MRP are involved in transport of AEDs. In the present study, we used in vivo microdialysis in rats to study whether the concentration of carbamazepine in the extracellular fluid of the cerebral cortex can be enhanced by inhibition of PGP or MRP, using the PGP inhibitor verapamil and the MRP inhibitor probenecid. Local perfusion with verapamil or probenecid via the microdialysis probe increased the extracellular concentration of carbamazepine. The data indicate that both PGP and MRP participate in the regulation of extracellular brain concentrations of the major AED carbamazepine.     

Multidrug resistance-associated protein is involved in the regulation of extracellular levels of phenytoin in the brain

The mechanisms that lead to drug resistance in epilepsy are not known. Recently, overexpression of multidrug transporters, such as multidrug resistance-associated protein (MRP), has been reported in surgically resected epileptogenic human brain tissue and suggested to contribute to the drug resistance of epilepsy. However, it is not known to what extent multidrug transporters such as MRP are involved in transport of antiepileptic drugs. In the present study, we used in vivo microdialysis in rats to study whether the concentration of phenytoin in the extracellular fluid of the cerebral cortex can be enhanced by inhibition of MRP, using the MRP inhibitor probenecid. Local perfusion with probenecid via the microdialysis probe significantly enhanced the extracellular concentration of phenytoin. The data indicate that MRP critically participates in the regulation of extracellular brain concentrations of the major antiepileptic drug phenytoin.     

Inhibition of multidrug transporters by verapamil or probenecid does not alter blood-brain barrier penetration of levetiracetam in rats

Overexpression of multidrug efflux transporters such as P-glycoprotein (Pgp; ABCB1) or multidrug resistance proteins (MRPs; ABCC) in the blood-brain barrier has recently been suggested to explain, at least in part, pharmacoresistance in epilepsy, which affects about 30% of all patients with this common brain disorder. The novel antiepileptic drug (AED) levetiracetam (LEV) is an effective and well tolerated drug in many patients with otherwise AED-refractory epilepsy. One explanation for the favorable efficacy of LEV in pharmacoresistant patients would be that LEV is not a substrate for Pgp or MRPs in the BBB. In the present study, we used in vivo microdialysis in rats to study whether the concentration of LEV in the extracellular fluid of the cerebral cortex can be modulated by inhibition of Pgp or MRPs, using the Pgp inhibitor verapamil and the MRP1/2 inhibitor probenecid. Local perfusion with verapamil or probenecid via the microdialysis probe did not increase the extracellular brain concentration of LEV, which is in contrast to various other AEDs which have been studied previously by the same experimental protocol in this model. The data indicate that brain uptake of LEV is not affected by Pgp or MRP1/2 which may be an important reason for its antiepileptic efficacy in patients whose seizures are poorly controlled by other AEDs.     

难治性癫(癎)相关耐药蛋白在局灶性皮质发育不良脑组织中的表达

目的 通过对P-糖蛋白、多药耐药相关蛋白和肺耐药相关蛋白在难治性癫痫相关局灶性皮质发育不良脑组织中表达部位的初步研究,以及对其在不同程度病变脑组织中表达量的比较,进一步阐明难治性癫疴的耐药机制,为癫(癎)患者的临床合理用药提供理论依据.方法 选取16例难治性癫(癎)患者手术切除脑组织标本作为患者组(局灶性皮质发育不良Ⅰ型和Ⅱ型患者各8例),5例无癫(癎)发作病史的胶质瘤患者手术切除脑组织标本的非病灶区域作为对照组.应用Envision二步法进行免疫组织化学标记,观察3种耐药蛋白在脑组织中的表达部位和表达强度;应用Western blot法进行SDS-聚丙烯酰胺凝胶电泳,对3种耐药蛋白在脑组织中的表达进行定量分析.结果 P-糖蛋白主要表达于毛细血管内皮细胞,多药耐药相关蛋白主要表达于脑组织内的神经元成分,肺耐药相关蛋白的表达则涌盖了毛细血管内皮细胞、气球细胞及病灶区域部分基质.3种耐药蛋白在局灶性皮质发育不良脑组织中的表达均显著高于对照组脑组织(P-糖蛋白:0.520±0.121,多药耐药蛋白:0.132±0.018,肺耐药相关蛋白:0.092 4-0.018,U=0.000,P<0.01),其中P-糖蛋白和肺耐药相关蛋白在局灶性皮质发育不良Ⅱ型患者的病灶区域(3.809±0.842、0.655±0.303)表达高于病灶周围区域(2.636 4±0.622、0.290±0.096,U=6.000、4.500,P<0.01).结论 P-糖蛋白、多药耐药相关蛋白和肺耐药相关蛋白在不同程度的局灶性皮质发育不良脑组织中具有不同的表达部位和表达量,提示其作用机制和作用强度有所差异.     

TLR4、MRP8在内侧颞叶癫痫幼大鼠海马中表达的动态变化

目的观察氯化锂-匹罗卡品致痫幼大鼠各期海马中Toll-样受体4(TLR4)、髓样相关蛋白8(MRP8)表达的变化,探讨其是否与内侧颞叶癫痫(MTLE)发生有关。方法 21d SD雄性大鼠90只,随机分对照组(30只)和模型组(60只),腹腔注射氯化锂。17～18h后模型组腹腔注射匹罗卡品诱导癫痫持续状态(SE);对照组予等量生理盐水取代匹罗卡品腹腔注射。按自发发作出现和稳定时间(自发痫性发作在致痫后约3w出现,8w趋稳定),对照组和模型组随机分6个亚组:急性模型组(SE后2h)、潜伏模型组(SE后3w)、慢性自发发作组(SE后8w)及相对应时间点对照组。每亚组动物10只。免疫组化、免疫印迹、RT-PCR技术测定各亚组幼大鼠海马内TLR4、MRP8的表达。结果 TLR4、MRP8在模型组海马内表达明显增多,以CA3、CA1、DG区显著;与对照组相比,差异有显著性(P0.05)。模型亚组内,TLR4、MRP8在急性期和慢性期表达明显增高,而潜伏期无明显表达变化;3组比较差异有显著性(P0.05)。结论大鼠海马内TLR4、MRP8表达增多可能与MTLE发生有关。探讨其机制可能为MTLE的治疗提供新的靶点。     

多药耐药相关蛋白-1在难治性颞叶癫痫患者脑组织中的表达及丙磺舒的干预作用

目的 观察难治性颞叶癫痫患者脑组织中多药耐药相关蛋白1( MRPl)及应用MRP1拮抗剂丙磺舒干预后的表达,探讨MRP1与难治性颞叶癫痫多药耐药的关系.方法 应用免疫组化检测难治性颞叶癫痫患者脑组织实验组和对照组MRP1的表达情况,同时应用免疫蛋白印记(Western blot)方法检测实验组、丙磺舒干预组和对照组MRP1的表达.结果 免疫组化结果显示MRP1在难治性颞叶癫痫患者脑组织中表达增强,与对照组比较差异有显著性(P＜0.05).Western blot结果显示丙磺舒干预组MRP1蛋白水平较实验组明显较少,差异有显著性(P＜0.05).结论 脑内高表达的MRP1参与难治性颞叶癫痫的耐药机制,丙磺舒可以降低脑组织内MRP1的表达.     

维拉帕米治疗难治性癫痫机制的研究

目的 研究抑制P-糖蛋白（p-glycoprotein，P-gp）的表达对难治性癫痫的治疗作用。方法用氯化锂-匹鲁卡品制作慢性颞叶癫痫模型，采用免疫组化法检测P-gp的表达水平；给予P-gp抑制剂维拉帕米，观察其对P-gp的抑制作用及大鼠癫痫发作的影响。结果难治性癫痫组P-gp表达水平较对照组明显增高，P-gp抑制剂维拉帕米可显著降低P-gp的表达水平，大鼠癫痫发作次数明显减少。结论 P-gp过度表达在难治性癫痫耐药性的产生中起重要作用。     

Distribution and functional activity of P-glycoprotein and multidrug resistance-associated proteins in human brain microvascular endothelial cells in hippocampal sclerosis

Multidrug resistance protein, also referred as P-glycoprotein (P-gp, MDR1; ABCB1) and multidrug resistance-associated protein (MRP) 1 (ABCC1) and 2 (ABCC2) are, thus far, candidates to cause antiepileptic drug (AED) resistance epilepsy. In this study, we investigated P-gp, MRP1 and MRP2 expression, localization and functional activity on cryosections and isolated human brain-derived microvascular endothelial cells (HBMEC) from epileptic patients (HBMEC-EPI) with hippocampal sclerosis (HS), as compared with HBMEC isolated from normal brain cortex (HBMEC-CTR). We examined the expression and distribution of three transporters, P-gp, MRP1 and MRP2 on two major parts of the resected tissue, the hippocampus and the parahippocampal gyrus (Gph). P-gp showed diffuse expression not only in endothelium but also by parenchymal cells in both the hippocampus and the Gph. MRP1 labeling was observed in parenchymal cells in the Gph. By contrast, MRP2 was mainly found in endothelium of the hippocampus. P-gp and MRP1 expression in the Gph was relatively high in the patient with long-term seizure history. Quantitative RT-PCR analysis of HBMEC revealed that MDR1, MRP1 as well as MRP5 (ABCC5) and MRP6 (ABCC6) were overexpressed in HBMEC-EPI at the mRNA level. HBMEC from both normal and epilepsy groups displayed protein expression of P-gp, whereas MRP1 and MRP2 were seen only in HBMEC-EPI. Accordingly, it is of particular interest that MRP functional activities were observed in HBMEC-EPI, but not in HBMEC-CTR. Our results suggest that complex MDR expression changes not only in the hippocampus but in the Gph may play a role in AED pharmacoresistance in intractable epilepsy patients with mesial temporal lobe epilepsy (MTLE) by altering the permeability of AEDs across the blood-brain barrier (BBB).     

Alterations of Glial Cell Function in Temporal Lobe Epilepsy

Summary: Purpose : Comparison of extracellular K⁺ regulation in sclerotic and nonsclerotic epileptic hippocampus.
Methods : Measurements of K⁺ signals with double-barreled K⁺-selective reference microelectrodes in area CA1 of slices from human and rat hippocampus, induction of increases in extracellular potassium concentration by repetitive alvear stimulation or iontophoresis, and block of inward-rectifying and background K⁺ channels in astrocytes by barium.
Results : In the CA1 pyramidal layer from normal rat hippocampus, barium augmented extracellular K⁺ accumulation induced by iontophoresis or antidromic stimulation in a dose-dependent manner. Similarly, barium augmented stimulusinduced K⁺ signals from nonsclerotic hippocampi (human mesial temporal lobe epilepsy). In contrast, barium failed to do so in sclerotic hippocampi (human mesial temporal lobe epilepsy, rat pilocarpine model).
Conclusions : Our findings suggest that in areas of reduced neuronal density (hippocampal sclerosis), glial cells adapt to permit rather large increases in extracellular potassium accumulation. Such increases might be involved in the transmission of activity through the sclerotic area.