Increased P-glycoprotein expression and decreased phenobarbital distribution in the brain of pentylenetetrazole-kindled rats

The purposes of this study were to investigate whether P-glycoprotein (P-GP) is overexpressed in the brain of pentylenetetrazole (PTZ)-kindled rats, and to investigate the effects of P-GP up-regulation on the distribution of phenobarbital (PB) in brain and its antiepileptic effects. Kindled rats were developed using a subconvulsive dose of PTZ (30 mg/kg, once every 2 days, i.p.) for 24 days. P-GP expression and function were measured by Western blot analysis and rhodamine 123 (Rho 123) distribution in brain. Kindled rats received 10 mg/kg of PB alone or co-administration of cyclosporine A (CsA, 5 mg/kg). At 60 min after administration of PB, concentrations of PB in brain and plasma were measured and the tissue-to-plasma concentration ratios of PB were calculated. Anticonvulsive effects of PB (13.2 mg/kg) alone or co-administration of CsA on the kindled rats were observed. The results showed that kindling resulted in 1.7-fold increase of P-GP level in brain, accompanied by significant decrease of tissue-to-plasma concentration ratios of Rho 123 and PB in hippocampus and cortex without affecting their concentrations in plasma. Co-administration of CsA reversed the decrease of PB concentration in brain without affecting PB level in plasma and significantly potentiated the anticonvulsive effects of PB. The present study demonstrated that chronic PTZ-kindling might increase P-GP expression and function in brain of rat, resulting in decrease of Rho 123 and PB levels in brain tissues. Co-administration of CsA increased PB levels in brain and enhanced anticonvulsive effects of PB by inhibiting P-GP function.     

选择性COX-2抑制剂NS-398的制备

目的制备选择性COX-2抑制剂NS-398。方法以2-氟硝基苯为起始原料,经4步反应化合成化合物NS-398。结果与结论用该方法可以在温和条件下合成出该药,最终产品纯度大于99%。     

Prevention of seizure-induced up-regulation of endothelial P-glycoprotein by COX-2 inhibition

In the epileptic brain, seizure activity induces expression of the blood-brain barrier efflux transporter, P-glycoprotein, thereby limiting brain penetration and therapeutic efficacy of antiepileptic drugs. We recently provided the first evidence that seizures drive P-glycoprotein induction through a pathway that involves glutamate-signaling through the NMDA receptor and cyclooxygenase-2 (COX-2). Based on these data, we hypothesized that selective inhibition of COX-2 could prevent seizure-induced P-glycoprotein up-regulation. In the present study, we found that the highly selective COX-2 inhibitors, NS-398 and indomethacin heptyl ester, blocked the glutamate-induced increase in P-glycoprotein expression and transport function in isolated rat brain capillaries. Importantly, consistent with this, the COX-2 inhibitor, celecoxib, blocked seizure-induced up-regulation of P-glycoprotein expression in brain capillaries of rats in vivo. To explore further the role of COX-2 in signaling P-glycoprotein induction, we analyzed COX-2 protein expression in capillary endothelial cells in brain sections from rats that had undergone pilocarpine-induced seizures and in isolated capillaries exposed to glutamate and found no change from control levels. However, in isolated rat brain capillaries, the COX-2 substrate, arachidonic acid, significantly increased P-glycoprotein transport activity and expression indicating that enhanced substrate flux to COX-2 rather than increased COX-2 expression drives P-glycoprotein up-regulation. Together, these results provide the first in vivo proof-of-principle that specific COX-2 inhibition may be used as a new therapeutic strategy to prevent seizure-induced P-glycoprotein up-regulation at the blood-brain barrier for improving pharmacotherapy of drug-resistant epilepsy.     

Antitussive effect of NS-398, a selective cyclooxygenase-2 inhibitor, in guinea pigs

Several reports have demonstrated that the number of capsaicin-induced coughs is increased in the presence of prostaglandins in the airway. Moreover, it has been reported that the expression of cyclooxygenase-2, which converts arachidonic acid to prostaglandins, was found in cultured human airway epithelial cells in the absence of inflammatory cytokine stimulation. Thus, it is possible that cyclooxygenase-2 inhibitor may produce an antitussive effect. To test this hypothesis, we investigated the effects of N-[2-(cyclohexyloxy)-4-nitrofenyl]-methane sulfonamide (NS-398), a selective cyclooxygenase-2 inhibitor, and 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl-pyrazole (SC-560), a selective cyclooxygenase-1 inhibitor, on capsaicin-induced coughs in guinea pigs. NS-398 (1-10 mg/kg, p.o.) dose-dependently and significantly reduced the number of capsaicin-induced coughs. In contrast, SC-560 (10 mg/kg, p.o.) did not reduce the number of capsaicin-induced coughs. The antitussive effect of NS-398 (10 mg/kg, p.o.) was not antagonized by pretreatment with methysergide (3 mg/kg, i.p.), a non-selective serotonin (5-HT) receptor antagonist, or glibenclamide (10 mg/kg, i.p.), an ATP-sensitive K(+) channel blocker. Furthermore, although NS-398 did not significantly affect the cough reflex induced by substance P (10(-16) M), it significantly reduced the capsaicin-induced release of substance P in bronchoalveolar lavage fluid (BALF). The present findings clearly show that cyclooxygenase-2 inhibitor, but not cyclooxygenasez-1 inhibitor, has a potent antitussive effect. Furthermore, it is possible that the antitussive action of NS-398 does not depend on centrally acting mechanisms, since 5-HT receptors play an important role in the cough-depressant activities of centrally acting antitussive drugs. NS-398 may exert peripheral antitussive effects by inhibiting the release of substance P from capsaicin-sensitive afferent C-fibers in the airways. These results suggest that cyclooxygenase-2 inhibitors may have a therapeutic benefit in reducing coughs.     

Evaluation of COX-1/COX-2 selectivity and potency of a new class of COX-2 inhibitors

A new class of selective cyclooxygenase-2 (COX-2) inhibitors has been identified by high throughput screening. Structurally distinct from previously described selective COX-2 inhibitors, these benzopyrans contain a carboxylic acid function and CF3 functionality. The compound SC-75,416 is a representative of this class. A range if in vitro and in vivo tests were employed to characterize its potency and selectivity. Using human recombinant enzymes, this compound displays a concentration that provides 50% inhibition (IC50) of 0.25 microM for COX-2 and 49.6 microM for COX-1. A mutation of the side pocket residues in COX-2 to COX-1 had little effect on potency suggesting that these inhibitors bind in a unique manner in COX-2 distinct from COX-2 inhibiting diaryl heterocycles. Using rheumatoid arthritic synovial cells stimulated with interleukin-1beta (IL-1beta) and washed platelets the compound displayed IC50 of 3 nM and 400 nM respectively. Potency and selectivity was maintained but predictably right shifted in whole blood with IC50 of 1.4 microM for lipopolysaccharide (LPS) stimulated induction of COX-2 and >200 microM for inhibition of platelet thromboxane production. SC-75,416 is 89% bioavailable and its in vivo half life is sufficient for once a day dosing. In the rat air pouch model of inflammation, the compound inhibited PGE2 production with an effective dose that provides 50% inhibition (ED50) of 0.4 mg/kg, while sparing gastric prostaglandin E2 (PGE2) production with an ED50 of 26.5 mg/kg. In a model of acute inflammation and pain caused by carrageenan injection into the rat paw, the compound reduced edema and hyperalgesia with ED50s of 2.7 and 4 mg/kg respectively. In a chronic model of arthritis the compound demonstrated an ED50 of 0.081 mg/kg and an ED(80) of 0.38 mg/kg. In a model of neuropathic pain, SC-75,416 had good efficacy. This compound's unique chemical structure and effect on COX enzyme binding and activity as well as its potency and selectivity may prove useful in treating pain and inflammation.     

Evaluation of the role of P-glycoprotein in the uptake of paroxetine, clozapine, phenytoin and carbamazapine by bovine retinal endothelial cells

Expression of the drug transport proteins, including P-glycoprotein (Pgp), in the brain vascular endothelium represents a challenge for the effective delivery of drugs for the treatment of several central nervous system (CNS) disorders including depression, schizophrenia and epilepsy. It has been hypothesized that Pgp plays a major role in drug efflux at the blood-brain barrier, and may be an underlying factor in the variable responses of patients to CNS drugs. However, the role of Pgp in the transport of many CNS drugs has not been directly demonstrated. To explore the role of Pgp in drug transport across an endothelial cell barrier derived from the central nervous system, the expression and activity of Pgp in bovine retinal endothelial cells (BRECs) and the effects of representative CNS drugs on Pgp activity were examined. Significant Pgp expression in BRECs was demonstrated by western analyses, and expression was increased by treatment of the cells with hydrocortisone. Intracellular accumulation of the well-characterized Pgp-substrate Taxol was markedly increased by the non-selective transporter inhibitor verapamil and the Pgp-selective antagonist PGP-4008, demonstrating that Pgp is active in these endothelial cells. In contrast, neither verapamil nor PGP-4008 affected the intracellular accumulation of [3H]paroxetine, [14C]phenytoin, [3H]clozapine or [14C]carbamazapine, indicating that these drugs are not substrates for Pgp. Paroxetine, clozapine and phenytoin were shown to be Pgp inhibitors, while carbamazapine did not inhibit Pgp at any concentration tested. These results indicate that Pgp is not likely to modulate patient responses to these drugs.     

Rofecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor potentiates the anticonvulsant activity of tiagabine against pentylenetetrazol-induced convulsions in mice

Numerous studies have implicated prostaglandins as potential modulators in seizure activity. The objective of the present study was to elucidate the effect of rofecoxib (selective COX-2 inhibitor) alone or in combination with newer antiepileptic drug tiagabine (γ-amino acid reuptake inhibitor) against pentylenetetrazol (PTZ) (80 mg/kg, i. p.)-induced chemoconvulsions in mice. Rofecoxib or tiagabine was administered 45 min prior to the PTZ challenge. In combination study, rofecoxib was administered 10 min before tiagabine and after 35 min the animals were challenged with convulsive dose of PTZ. Mean onset time of jerks, clonus and extensor phases following PTZ challenge was noted. Pretreatment with rofecoxib (1–5.0 mg/kg, i. p.) or tiagabine (1–10 mg/kg, i. p.) dose dependently protected the animals against PTZ-induced convulsions. The mean onset time of jerks, clonus and extensor phase were increased. A subeffective dose of rofecoxib (0.5 mg/kg, i. p.) potentiated the effect of subprotective dose of tiagabine (0.5 mg/kg, i. p.). The results of the present study suggested that the protective effect of rofecoxib, a COX-2 inhibitor against PTZ-induced convulsions may be possibly through the GABAergic modulation. Rofecoxib may have a place as adjuvant therapy with standard antiepileptic drugs such as tiagabine in the treatment of epilepsy. Received 10 August 2006; revised and accepted 30 August 2006     

Pharmacokinetics of acute and sub-chronic aripiprazole in P-glycoprotein deficient mice

Background

P-glycoprotein (P-gp), an efflux transporter localized in the blood-brain barrier, limits the access of multiple xenobiotics to the central nervous system (CNS). For the new antipsychotic aripiprazole and its active metabolite dehydroaripiprazole differences in disposition in blood and brain were investigated after acute and sub-chronic administration in a P-gp knockout mouse model.

Methods

Serum and brain concentrations of both drugs were measured at several time points 1-24 h after i.p. injection of 10 mg/kg aripiprazole and after 11 days of sub-chronic administration in several tissues. Moreover, the expression of P-gp was determined by Western blot analysis after sub-chronic administration of the drug.

Results

In both wild type and abcb1ab (−/−) mice concentration of aripiprazole in brain were up to 9 fold higher than in serum. For dehydroaripiprazole the mean brain to serum ratios were below two. Brain to serum concentrations of both substances were significantly higher after acute and sub-chronic administration in connection to the expression of P-gp indicated by higher levels in abcb1ab (−/−) mice especially for dehydroaripiprazole.Sub-chronic aripiprazole treatment in WT animals had no effect on P-gp expression in the blood-brain barrier.

Conclusions

Aripiprazole and, even more pronounced its active metabolite dehydroaripiprazole could be identified as substrates of P-gp. The efflux transporter P-gp must therefore be considered as a relevant factor that contributes to wanted or unwanted clinical effects in patients treated with aripiprazole.     

NS398 protects cells from sodium nitroprusside-mediated cytotoxicity through enhancing HO-1 induction independent of COX-2 inhibition

Heme oxygenase-1 (HO-1) plays a preventive role in oxidative stress. In contrast, COX-2 is involved in the pathogenesis of many inflammatory diseases, thus COX-2 inhibitor is believed to exert anti-inflammatory properties by blocking COX-2. Recently, however, salicylate the active metabolite of aspirin showed COX-independent anti-inflammatory effects through induction of HO-1. Thus, we hypothesized that HO-1 are induced as an adaptive response to sodium nitroprusside (SNP) and play a protective role against cytotoxicity. Moreover, we investigated the protective effect of NS398 known as a selective COX-2 inhibitor on SNP-mediated cytotoxicity, and whether the protective effect of NS398 is due to COX-2 inhibition or not. SNP induced cytotoxicity in a dose-dependent manner, which was enhanced by inhibition of HO-1, suggesting that HO-1 acts in an adaptive response to SNP. Interestingly, NS398 decreased SNP-mediated cytotoxicity whereas COX-2 siRNA did not. Furthermore, NS398 enhanced SNP-induced HO-1 induction even though NS398 alone failed to induce HO-1 protein expression. In addition, NS398 enhanced SNP-induced COX-2, even though NS398 effectively inhibited SNP-mediated PGE₂ production. These results demonstrate that NS398 exerts cytoprotective effects by inducing HO-1 independent of COX-2 inhibition.     

Combined effects of epileptic seizure and phenobarbital induced overexpression of P-glycoprotein in brain of chemically kindled rats

Background and purpose:

The multidrug resistance of epilepsy may result from the overexpression of P-glycoprotein, but the mechanisms are unclear. We investigated whether the overexpression of P-glycoprotein in the brains of subjects with pharmacoresistant epilepsy resulted from both drug effects and seizure activity.

Experimental approach:

Kindled rats were developed by injecting a subconvulsive dose of pentylenetetrazole (33 mg·kg⁻¹·day⁻¹, i.p.) for 28 days. Groups were then treated with an oral dose of phenobarbital (45 mg·kg⁻¹·day⁻¹) for 40 days. In accord with behavioural observations, P-glycoprotein activity in brain was assessed using brain-to-plasma concentration ratios of rhodamine 123. P-glycoprotein levels in the brain regions were further evaluated using RT-PCR and Western blot analysis. The distribution of phenobarbital in the brain was assessed by measuring phenobarbital concentrations 1 h following its oral administration.

Key results:

The kindling significantly increased P-glycoprotein activity and expression. Good associations were found among P-glycoprotein activity, expression and phenobarbital concentration in the hippocampus. Short-term treatment with phenobarbital showed good anti-epileptic effect; the maximum effect occurred on day 14 when overexpression of P-glycoprotein was reversed. Continuous treatment with phenobarbital had a gradually reduced anti-epileptic effect and on day 40, phenobarbital exhibited no anti-epileptic effect; this was accompanied by both a re-enhancement of P-glycoprotein expression and decreased phenobarbital concentration in the hippocampus. P-glycoprotein function and expression were also increased in age-matched normal rats treated with phenobarbital.

Conclusions and implications:

The overexpression of P-glycoprotein in the brain of subjects with pharmacoresistant epilepsy is due to a combination of drug effects and epileptic seizures.     

胰岛素抵抗大鼠血脑屏障上P-糖蛋白表达和转运功能的研究

目的:建立胰岛素抵抗大鼠模型,观察胰岛素抵抗大鼠血脑屏障(BBB)上P-糖蛋白(P-gp)的表达和转运功能.方法:采用高脂饲料喂养制备胰岛素抵抗大鼠模型,用口服葡萄糖耐量、胰岛素耐量和胰岛素敏感性指数评价大鼠胰岛素抵抗.用伊文思蓝检测BBB通透性,用透射电镜观察BBB的完整性,用Westem blot测定BBB上P-gp的蛋白水平,用RT-PCR技术检测BBB上mdrla/mdrlb的mRNA水平,用Rh123累积实验测定BBB上P-gp的转运功能.结果:用高脂饲料喂养大鼠6周后,葡萄糖耐量和胰岛素耐量明显异常,空腹胰岛素含量显著升高,胰岛素敏感性显著下降.胰岛素抵抗大鼠BBB上P-gp表达水平和转运功能显著下降,但BBB通透性和完整性未发生明显改变.结论:胰岛素抵抗下调BBB上P-gp表达和转运功能.     

全颅常规外照射对大鼠血脑屏障通透性的影响及相关机制研究

目的探讨全颅常规外照射增加大鼠血脑屏障药物通透性的产生机制,为临床对颅内肿瘤寻找合适的化疗时机提供理论依据。方法 60只正常成年Wistar大鼠随机分为5组,分别采用0、10、20、30、40Gy,^60Coγ射线进行全脑常规分割外照射,2Gy/次、1野/次,5次/周。各组完成照射计划后16h经尾静脉注射氨甲喋呤（MTX）25mg/kg,2h后采集脑脊液,用RP-HPLC法检测其中的MTX浓度。之后所有大鼠均断头取脑,40g/L中性甲醛固定24h,石蜡包埋,采用免疫组化法检测各组大鼠血脑屏障上P-gp的表达情况。结果对照组P-gp阳性表达最强,10Gy组与对照组,20Gy与30Gy组,40Gy组分别与20Gy、30Gy组比较无统计学意义（P〉0.05）,其余各组比较均有统计学意义（P〈0.05）。各组大鼠脑脊液中的MTX平均浓度分别为：0.06、0.08、0.19、0.24、0.23mg/L。经方差分析及秩和检验,10Gy组与对照组,20Gy与30Gy组,40Gy组分别与20Gy、30Gy组比较无统计学意义（P〉0.05）,其余各组比较均有统计学意义（P〈0.05）。结论一定剂量的放射线可能通过降低血脑屏障上P-gp的表达,增加其对药物的通透性,并且在放射剂量达到20Gy的时候化疗效果最好。     

NS-398对舌鳞癌基质金属蛋白酶2蛋白表达的影响

目的探讨环氧化酶2(COX-2)抑制剂NS-398对舌鳞癌基质金属蛋白酶2(MMP-2)蛋白表达的影响。方法将舌鳞癌细胞株Tca8113分为对照组(A组)和NS-398 20、40、80μmol/L加药组(分别为B1、B2、B3组);荧光免疫组化和Western blot法检测各组MMP-2蛋白表达情况。结果 B1、B2、B3组MMP-2蛋白表达呈递减趋势,且均较A组明显降低(免疫组化法:366073.100±116272.561、241739.000±12320.270、120672.100±5976.391vs.591518.000±17356.450;Western blot法:0.620±0.084、0.425±0.058、0.172±0.025vs.0.950±0.124)(P<0.05)。结论 NS-398在Tca8113细胞中能抑制MMP-2蛋白表达,并且MMP-2蛋白表达随着药物浓度的增加而减少。     

ERK信号转导途径在小檗碱抑制脂多糖诱导的COX一2表达中的作用

目的探讨小檗碱是否抑制脂多糖诱导的COX-2mRNA及蛋白表达,以及小檗碱是否通过ERK信号转导途径抑制cOx-2的表达。方法取健康志愿者外周血,分离及培养单核细胞,分为五组,分别为对照组;脂多糖（Lipopolysaccharide,LPS）组;LPS＋小檗碱25μmol／L组;LPS＋小檗碱50μmol/L组;LPS＋小檗碱100μmoL／L组。分别在培养后30min,6h,12h,24h提取细胞,行RT—PCR法测定COX-2mRNA水平,行westemblot法测定ERK、P—ERK及COX-2蛋白水平。同时加入选择性ERK抑制剂,分别测定C0X-2mRNA及蛋白水平。结果与对照组相比,LPS组COX-2mRNA及蛋白表达明显增强（P〈0．01）。与LPS组相比,小檗碱组COX-2mRNA及蛋白表达明显抑制（P〈0．05）,且随着浓度增加,抑制作用更明显,在给药后12h,小檗碱对COX-2抑制作用最强。与LPS组相比,小檗碱组ERK活性水平有明显统计学差异（P〈0．05）。加入ERK抑制剂之后,COX-2mRNA及蛋白水平降低明显（P〈0．05）。结论小檗碱能抑制人外周血单核细胞cOx-2mRNA及蛋白水平,其作用程度呈浓度依赖性,小檗碱对ERK活性蛋白表达有明显抑制作用。小檗碱可能通过ERK信号转导途径抑制人外周血单核细胞C0x_2mRNA及蛋白表达。     

Differential inhibition of cyclooxygenase-1 (COX-1) and-2 (COX-2) by NSAIDS: Consequences on anti-inflammatory activity versus gastric and renal safety

The discovery of an inducible isoform of cyclooxygenase (COX-2) requires a refinement of the theory that inhibition of cyclooxygenase activity is responsible for both therapeutic and side-effects of nonsteroidal anti-inflammatory drugs (NSAIDs). Pharmacological results with developmental compounds suggest that COX-2 is the relevant target for the therapeutic (i.e. anti-inflammatory) effects of NSAIDs, whereas gastric and renal side-effects are related to inhibition of constitutive COX-1. However a role of COX-1 in inflammation cannot be excluded. Furthermore, more research effort is needed to investigate the functional relevance of COX-2 in normal tissue.     

脑源性神经营养因子对戊四氮致癫痫大鼠海马神经肽Y表达的影响

目的 研究侧脑室内注入脑源性神经营养因子(BDNF)对戊四氮(PTZ)致癫痫大鼠海马区神经肽Y(NPY)表达的影响.方法 采用PTZ制备大鼠癫痫模型.立体定向自侧脑室注入BDNF.免疫组化观察NPY在海马CA1 区的表达,放射免疫测定海马,皮层,下丘脑组织NPY匀浆浓度.结果 免疫组化显示点燃模型组阳性反应神经元增多,BDNF干预组阳性反应神经元明显增多.点燃模型组海马组织匀浆NPY的放射免疫测定浓度增高 (P＜0.05);BDNF干预组海马组织匀浆NPY的放射免疫浓度明显高于点燃模型组(P＜0.05).结论 NPY参与了癫痫的发病过程,BDNF可以增加脑组织NPY浓度.     

环氧合酶-2及其抑制剂在胰腺癌血管靶向治疗中的作用

胰腺癌的诊治目前仍是医学界的难题,血管生成是胰腺癌生长和转移的必要因素。环氧合酶(cyclooxygenase,COX)为花生四烯酸代谢过程中的关键酶,存在COX-1及COX-2两种同工酶,其中COX-2在胰腺癌的发生发展及胰腺癌血管生成中发挥重要作用。COX-2抑制剂可分为非选择性及选择性两种,两种COX-2抑制剂都对胰腺癌及其血管形成的发生与进展存在抑制作用,COX-2抑制剂抗肿瘤血管形成的机制可能是抑制血管内皮生长因子(VEGF)、缺氧诱导因子-1及基质金属蛋白酶(MMP)的表达、降低前列腺素(PGs)及其他血管生成因子的表达、促进内皮细胞凋亡、抑制内皮细胞侵袭力和影响一氧化氮合酶(NOS)的表达。     

Differences in the transport of the antiepileptic drugs phenytoin, levetiracetam and carbamazepine by human and mouse P-glycoprotein

In view of the important role of P-glycoprotein (Pgp) and other drug efflux transporters for drug distribution and resistance, the identification of compounds as substrates of Pgp-mediated transport is one of the key issues in drug discovery and development, particularly for compounds acting on the central nervous system. In vitro transport assays with Pgp-transfected kidney cell lines are widely used to evaluate the potential of compounds to act as Pgp substrates or inhibitors. Furthermore, such cell lines are also frequently utilized as a substitute for more labor-intensive in vitro or in vivo models of the blood-brain barrier (BBB). Overexpression of Pgp or members of the multidrug resistance protein (MRP) family at the BBB has been implicated in the mechanisms underlying resistance to antiepileptic drugs (AEDs) in patients with epilepsy. Therefore, it is important to know which AEDs are substrates for Pgp or MRPs. In the present study, we used monolayers of polarized MDCKII dog kidney or LLC-PK1 pig kidney cells transfected with cDNA containing either human MDR1, MRP2 or mouse mdr1a and mdr1b sequences to measure the directional transport of AEDs. Cyclosporin A (CsA) and vinblastine were used as reference standards for Pgp and MRP2, respectively. The AEDs phenytoin and levetiracetam were directionally transported by mouse but not human Pgp, whereas CsA was transported by both types of Pgp. Carbamazepine was not transported by any type of Pgp and did not inhibit the transport of CsA. In contrast to vinblastine, none of the AEDs was transported by MRP2 in transfected kidney cells. The data indicate that substrate recognition or transport efficacy by Pgp differs between human and mouse for certain AEDs. Such species differences, which are certainly not restricted to human and mouse, may explain, at least in part, the controversial data which have been previously reported for AED transport by Pgp in preparations from different species. However, because transport efficacy of efflux transporters such as Pgp or MRP2 may not only differ between species but also between tissues, the present data do not exclude that the AEDs examined are weak substrates of Pgp or MRP2 at the human BBB.     

己美舒利对大鼠脑损伤后脑水肿及髓过氧化物酶、金属蛋白酶-2的影响

目的阐明环氧化酶-2（cox-2）抑制剂尼美舒利对大鼠创伤性脑损伤的影响与机制。方法健康雄性SD大鼠40只,随机分为4组：对照组、尼美舒利组【6mg／（kg·d）1、创伤组、创伤＋尼美舒利组f6mg／（kg·d）1。利用300g,／m的自由落体重力打击装置创建SD大鼠创伤性脑损伤模型,创伤后24h进行神经功能评分,随后处死动物并断头取脑组织。脑水肿及血脑屏障通透性分别以干湿重称重法及伊文思蓝染色测定,测量脑组织中髓过氧化物酶（MPO）及金属蛋白酶-2（MMP-2）的含量以及病理组织形态学观察。结果创伤组脑组织含水量及EB含量比对照组明显增加（P〈0．05）,创伤＋尼美舒利组脑组织含水量及EB含量比创伤组明显减少（P〈0．01）。创伤＋尼美舒利组脑组织MMP-2、MPO表达比创伤组减少,MPO蛋白表达与MMP-2蛋白表达呈正相关。结论在创伤性脑损伤大鼠模型中,尼美舒利通过保持血脑屏障完整性,抑制MPO、MMP-2的过度表达（可能通过其抗炎能力）而发挥其神经保护作用。     

不同类型胃息肉组织中COX-2基因蛋白的表达及其意义

目的探讨不同类型胃息肉组织中环氧合酶-2(COX-2)蛋白的表达情况及其临床意义。方法对内镜下摘除129例胃息肉进行病理组织分类,并采用免疫组织化学技术检测COX-2蛋白的表达情况。结果在129例胃息肉中经HE染色病理识别有增生性息肉57例,炎性息肉39例,腺瘤样息肉33例;COX-2在它们的阳性表达率分别为29.8%(17/57)、38.5%(15/39)和63.6%(21/33),各组之间比较差异显著(P<0.05),以腺瘤样息肉组表达率最高(P<0.01)。结论检测胃息肉组织中COX-2蛋白的表达情况对它的发病机理及恶性病变倾向提供依据,对其治疗和随访具有重要的指导作用。