D-聚甘酯对原代培养胎大鼠皮层神经元细胞外液NO的影响

体外培养胎大鼠皮层神经元,利用低糖低氧环境造成脑缺血模型,观察了Ｄ－城酯对低糖低氧所致ＮＯ释放的影响。结果表明Ｄ－聚甘酯５,２５,５０ｍｇ．Ｌ＾－１涌抑制低糖氧所导致的ＮＯ释放的增多。提示：Ｄ－聚甘酯可能以非ＮＯ途径发挥其脑血保护作用。     

甘糖酯对家兔全脑缺血再灌损伤的保护作用

甘糖酯是一种新型的低分子量、低抗凝活性的多糖类海洋药物。本文报道甘糖酯对４动脉阻断家兔全脑缺血再灌损伤脑组织过氧化脂质（ＭＤＡ）、超氧化物歧化酶（ＳＯＤ）、谷胱甘肽过氧化物酶（ＧＳＨ－Ｐｘ）、一氧化氮（ＮＯ）和脑含水量的影响。结果显示，甘糖酯可降低全脑缺血再灌损伤的ＭＤＡ含量，提高ＳＯＤ和ＧＳＨ－Ｐｘ活性，降低脑含水量，对ＮＯ无明显影响，提示甘糖酯对全脑再灌损伤有明显的抗氧化作用。     

盐酸二氢埃啡对小鼠,大鼠和豚鼠肠道平滑肌的作用

目的：研究ＤＨＥ对肠道平滑肌的作用，方法：小鼠，大鼠和豚鼠离体和在体肠道平滑肌上，以吗啡为对照。比较了ＤＨＥ与吗啡对肠道平滑肌作用的异同。结果；吗啡和ＤＨＥ减慢小鼠肠推是运动的ＥＤ５０分别为２．７９ｍｇ．ｋｇ＾－１和３．２３μｇ．ｋｇ＾－１，ＤＨＥ３６～６０μｇ．ｋｇ＾－１ｓｃ可松弛小鼠在体肠道平滑肌，在相同的实验条件下，吗啡５～２０ｍｇ．ｋｇ＾－１，ｓｃ可剂量依赖性地收缩小鼠在体肠道平滑肌；在小     

(-),( )黄皮酰胺对鼠脑内 NMDA- 受体的影响

用［３Ｈ］ＭＫ８０１放射配体竟争结合法测定了（－），（＋）黄皮酰胺对大鼠前脑，海马，皮层等部位突触膜的ＮＭＤＡＲ的作用，以探讨其促智机制。同时用饱和实验分析ｐｏ给药１０ｄ后，小鼠脑内该受体密度的变化。结果表明：（－），（＋）黄皮酰胺对脑内各部位的ＮＭＤＡ受体均无特异亲和力。但（－）黄皮酰胺在体给药１０ｄ后能使小鼠脑内ＮＭＤＡ受体密度显著增高，并呈一定的量效关系。提示黄皮酰胺的药理作用有光学选择性；（－）黄皮酰胺增加脑内ＮＭＤＡ受体密度为其促智作用提供了重要理论依据。     

单甘酯对血小板粘附聚集功能的影响

观察了单甘酯（Ｇｌｙｃｏｌ ｍａｎｎａｔｅＳｕｌｆａｔｅ,ＧＭＳ）对血小板聚集,粘附功能及小鼠尾出血时间的影响。结果表明单甘酯２５,５０ｍｇ．ｋｇ＾－１剂量组对血小板粘附有显著抑制作用,Ｐ〈０．０１;２５,５０,１００ｍｇ．ｋｇ＾＆－１能明显抑制胶原和花生四烯酸诱导的血小板聚集,对ＡＤＰ诱导的血小板聚集无抑制作用。单甘酯４０,８０ｍｇ．ｋｇ＾－１可明显延长小鼠尾出血时间。结果证明单甘酯有明显的抗血     

烟碱对大脑皮层毒蕈碱型受体与其激动剂和拮抗剂结合的调节

目的：研究烟碱对脑Ｍ受体结合性能的调节作用。 方法：测定烟碱对脑Ｍ受体与其激动剂［＾３Ｈ］氧颤莫林－Ｍ和拮抗ｌ－［＾３Ｈ］奎纽定二苯羟乙酸（ＱＮＢ）结合的影响。 结果：大鼠大脑皮层膜标本经烟碱预处理后，Ｍ受体与［＾３Ｈ］氧颤莫林－Ｍ特异性结合的平衡解离常数降低，最大结合量不变；Ｍ受体与ｌ－［＾３Ｈ］ＱＮＢ特异性结合的平衡解离常数增高，最大结合量也不变。烟碱对Ｍ受体与ｌ－［＾３Ｈ］ＱＮＢ特异性结合的     

胞内储备钙参与3,4—二氨基吡啶诱发去甲肾上腺素释放

目的：用大鼠海马脑片研究３，４－二氨基吡啶（ＤＡＰ）诱发去甲肾上腺素胞外钙－不依赖释放的机制，方法：大鼠海马脑片用（＾３Ｈ）ＮＥ孵育后，进行表面灌流，测（＾３Ｈ）ＮＥ释放。结果：在胞外无镍条件下，ＤＡＰ能显著加强（＾３Ｈ）ＮＥ释放，当用利血平使囊泡（＾３Ｈ）ＮＥ排空，则ＤＡＰ作用消失，用高浓度地昔帕明刺激ＩＰ３－敏感的胞内Ｃａ＾２＋储备库，能有力地增强（＾３Ｈ）ＮＥ释放，而高浓度咖啡因对（＾３Ｈ）     

米托蒽醌聚乳酸缓释毫微粒冻干针剂在动物体内的靶向性研究

目的：比较肝靶向米托蒽醌聚乳酸缓释毫微粒（ＤＨＡＱ－ＰＬＡ－ＮＰ）冻干针剂和ＤＨＡＱ水针剂在小鼠体内的分布规律,验证前者的肝靶向性。方法：采用ＨＰＬＣ法测定静注ＤＨＡＱ－ＰＬＡ－ＮＰ和ＤＨＡＱ水针剂后小鼠血液、心、肝、脾、肺、肾的药物浓度,由此计算各器官的相对百分含量。结果：ＤＨＡＱ－ＰＬＡ－ＮＰ冻干针剂在肝脏的分布明显高于ＤＨＡＱ水针剂,在其它器官中的含量则低于水针剂,给药２４小时后药物在肝中的     

藻酸双酯钠和甘糖酯对急性心肌梗死患者红细胞变形能力保护作用…

为探讨藻酯双酯钠（ＰＳＳ）和甘糖酯（ＰＧＭＳ）对急性心肌梗死（ＡＭＩ）患者红细胞变形能力（ＥＤ）保护作用的机制，检测了５２例ＡＭＩ患者红细胞流动指数（ＥＦＩ），红细胞膜Ｎａ＾＋，Ｋ＾＋－ＡＴＰ酶和谷胱甘肽过氧化物酶ＧＳＨ－Ｐｘ活性及红细胞膜脂质过氧化物（ＬＰＯ）的变化，同时观察了ＰＳＳ和ＰＧＭＳ在体外对ＥＤ，Ｎａ＾＋，Ｋ＾＋－ＡＴＰ酶，ＧＳＨ－Ｐｘ和ＬＰＯ的影响，结果显示，ＡＭＩ患者ＥＦＩ，ＬＰＯ     

LDL-ACM复合物的药代动力学与组织分布

以＾１２５Ｉ标记的ＬＤＬ－ＡＣＭ复合物为示踪剂,研究了其在小鼠体内的药代动力学及组织分布。结果表明：小鼠单次尾静脉给药后的药代动力学符合二房室模型一级动力学,其药代动力学参数与天然ＬＤＬ相似;组织分布结果显示,尾静脉单次注入９０ｍｉｎ后,ＬＤＬ－ＡＣＭ复合物在Ｈ２２荷瘤小鼠体内的分布顺序为肾上腺〉肝脏〉瘤组织〉脾和肾〉心和肺。与天然ＬＤＬ的分布基本一致。     

微透析和高效液相色谱法测定大鼠脑内天麻素及天麻苷元含量

目的考察不同剂量天麻素皮下及口服给药后大鼠脑内的天麻素及其代谢产物天麻苷元的浓度变化。方法采用脑内微透析技术进行在体动态取样,建立了高效液相-串联四级杆质谱方法测定脑透析液中的天麻素含量,建立了高效液相-二极管阵列检测方法测定脑透析液中的天麻苷元含量。结果两种给药方式大鼠不同脑区内天麻素浓度均较低,天麻苷元脑内浓度明显高于其原型药物天麻素。结论天麻素的血脑屏障透过能力差,但其活性代谢产物天麻苷元能够较好地进入脑内发挥作用。     

In vivo interaction of cabergoline with rat brain dopamine receptors labelled with [3H]N-n-propylnorapomorphine

Cabergoline is a potent dopaminergic agent that interacts with agonists and antagonists of dopamine receptors in vitro. We studied the binding of [3H]N-n-propylnorapomorphine ([3H]NPA) to dopamine receptors after i.v. and oral administration of cabergoline to determine whether cabergoline crosses the blood-brain barrier; bromocriptine was used as a reference drug. Cabergoline and/or its active metabolite(s) did cross the blood-brain barrier and reach dopamine receptors. Comparative time-course analysis of the regional inhibition of [3H]NPA binding showed that cabergoline was more potent than bromocriptine in inhibiting [3H]NPA binding and that it occupied the receptor for longer. These effects were observed in all areas of the rat brain studied (striatum, olfactory tubercles, adeno- and neurohypophysis, thalamus and hypothalamus). Further studies in the striatum and adenohypophysis showed that cabergoline receptor occupancy was dose-dependent and still detectable 72 h after i.v. administration of the drug. While cabergoline was more potent in the striatum than in the adenohypophysis when administered i.v., the reverse was observed after its oral administration. Cabergoline was equally potent in the adenohypophysis after oral and i.v. administration, as determined 1 and 8 h later.     

Temporal oscillations of serum electrolytes in N-phthaloyl GABA-treated rats

N-Phthaloyl gamma-aminobutyric acid (P-GABA) has been known to cross the blood-brain barrier and ultimately to increase brain GABA level. In the present study, P-GABA was administered to Wistar rats for 21 days and circadian rhythms of sodium, potassium, and calcium levels in serum were studied under seminatural light-dark conditions. P-GABA administration caused desynchronization of the rhythms and advanced the peak times of serum electrolytes. Exogenously administered P-GABA could alter the photic information received by the clock. The results could be explained by slightly less or more than 1-h daily delays, which would bring the peak times to the points 21 days after the start of administration. The changes in amount of electrolytes after P-GABA administration are discussed.     

Central nervous system blockade by peripheral administration of AT1 receptor blockers

After peripheral administration, AT(1) receptor blockers appear to be able to enter the brain and cause AT(1) receptor blockade in the central nervous system. In the current study, we investigated the effects of subcutaneous administration of embusartan versus losartan on inhibition of AT(1) receptor binding in rat brain by in vitro autoradiography. At 4 hours after single doses of 5, 30, or 100 mg/kg, both losartan and embusartan decreased iodine 125I Ang II binding dose dependently in brain structures that express AT(1) receptors both outside (e.g., organum vasculosum laminae terminalis) and within (e.g., paraventricular nucleus) the blood-brain barrier. At low doses, embusartan was twofold more potent than losartan inside but not outside the blood-brain barrier. After chronic treatment (30 mg/kg daily for 6 days), at 4 hours after the last dose, embusartan still caused more inhibition than losartan in the brain structures inside the blood-brain barrier. At 24 hours after the last dose, a modest, better inhibition for embusartan versus losartan remained: from 15% to 33% versus 10% to 24%, respectively. At 36 hours after the last dose, the inhibition for both blockers had almost completely disappeared inside the blood-brain barrier but persisted in, for example, the kidneys. These results demonstrate that-likely because of its high lipophilic character-embusartan appears to penetrate the blood-brain barrier more easily than losartan and therefore causes more effective AT(1) receptor blockade in nuclei within the blood-brain barrier.     

Manipulating neuropeptidergic pathways in humans: a novel approach to neuropharmacology?

Given the tremendous number of neuropeptides, which are synthesized in the central nervous system, the brain can be viewed as one of the most prominent endocrine organs. Elucidation of the functions of these peptides is hampered by the facts that after intravenous administration access to brain receptors is prevented or impaired by the blood-brain barrier. Here, we provide evidence that intranasal administration can be a way to circumvent the blood-brain barrier. Selected experiments will be reported indicating that peptides after intranasal administration in humans can specifically alter a great variety of brain functions. For vasopressin, we demonstrated improving effects of long-term intranasal treatment on sleep in elderly people. Insulin showed improving effects of short-term memory functions. For adrenocorticotropin/melanocyte stimulating hormone, ACTH/MSH-(4-10), a twofold action was isolated: The melanocortin fragment diminished selective attention and, with subchronic administration, reduced body fat. These results could provide the basis for developing a new, specific, and "soft" neuropharmacology.     

P-Glycoprotein Attenuates Brain Uptake of Substrates After Nasal Instillation

Purpose. Previous literature has suggested the absence of an effective barrier between the nasal mucosa and the brain for compounds administered via the nasal route. These experiments were conducted to elucidate the role of the blood-brain barrier efflux transporter P-glycoprotein (P-gp) in attenuating delivery of P-gp substrates to the brain after nasal administration in mice. Methods. Brain uptake of several radiolabeled P-gp substrates, was measured in P-gp-deficient and P-gp-competent mice following nasal instillation. Additional experiments were performed to assess the potential for enhancing brain uptake by inhibiting P-gp with intranasal rifampin. Results. All substrates examined were measurable in brain tissue within 2 min. Substrate accumulation in P-gp-deficient mice was higher than in P-gp-competent animals; the degree to which P-gp attenuated brain uptake after nasal administration was similar to that during in situ brain perfusion. Co-administration of rifampin enhanced brain uptake of relevant substrates, and resulted in complete elimination of P-gp-mediated transport for ³H- verapamil. Conclusions. P-gp attenuates brain accumulation of intranasally-administered P-gp substrates. Thus, biochemical components of the blood-brain barrier, such as efflux transporters may influence brain penetration after nasal administration. Co-administration of a P-gp inhibitor enhances the brain uptake of relevant substrates, suggesting that the transporter barrier functions may be reversible.     

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.     

Passage of erythropoietic agents across the blood-brain barrier: a comparison of human and murine erythropoietin and the analog darbepoetin alfa

Studies have suggested that erythropoietin (EPO) may be used to treat stroke in both animals and humans. It is thought to exert its effects directly on the brain and studies with therapeutic doses have shown that it can cross the blood-brain barrier. Here, we compared in a blinded fashion the ability of three erythropoietic agents (murine erythropoietin, human erythropoietin, and darbepoetin alfa, an analog of human erythropoietin in clinical use) to cross the blood-brain barrier of the mouse. High-performance liquid chromatography (HPLC) results showed that all three erythropoietic agents were enzymatically resistant in brain and blood. The unidirectional blood-to-brain influx rates (Ki) as measured by multiple-time regression analysis showed that all the erythropoietic agents crossed the blood-brain barrier at about the same rate as albumin, suggesting that they cross the blood-brain barrier by way of the extracellular pathways. No saturable component to influx was found, but indirect evidence suggested a brain-to-blood efflux system. The percent of the intravenously injected dose taken up per gram of brain (%Inj/g) ranged from 0.05 to 0.1 %Inj/g among the three erythropoietic agents and peaked about 3 h after IV injection. For other substances, this range of %Inj/g is known to produce direct effects on brain function. We conclude that erythropoietic agents cross the blood-brain barrier by way of the extracellular pathways in amounts that are likely sufficient to explain their neuroprotective effects.     

Design, Synthesis and Brain Uptake of LAT1-Targeted Amino Acid Prodrugs of Dopamine

Purpose

Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enhance the brain uptake of cationic dopamine by utilizing the large amino acid transporter 1 (LAT1) at the BBB by prodrug approach.

Methods

Three amino acid prodrugs of dopamine were synthesized and their prodrug properties were examined in vitro. Their LAT1-binding and BBB-permeation were studied using the in situ rat brain perfusion technique. The brain uptake after intravenous administration and the dopamine-releasing ability in the rat striatum after intraperitoneal administration were also determined for the most promising prodrug.

Results

All prodrugs underwent adequate cleavage in rat tissue homogenates. The prodrug with phenylalanine derivative as the promoiety had both higher affinity for LAT1 and better brain uptake properties than those with an alkyl amino acid -mimicking promoiety. The phenylalanine prodrug was taken up into the brain after intravenous injection but after intraperitoneal injection the prodrug did not elevate striatal dopamine concentrations above those achieved by corresponding L-dopa treatment.

Conclusions

These results indicate that attachment of phenylalanine to a cationic drug via an amide bond from the meta-position of its aromatic ring could be highly applicable in prodrug design for LAT1-mediated CNS-delivery of not only anionic but also cationic polar drugs.     

Some observations indicating a low brain uptake of [3H]Nle11-Substance P

The studies concerning the problem of whether an exogenous neuropeptide is able to enter the brain tissue were extended to the undecapeptide Substance P (SP). The amount of radioactivity 15 s after intracarotid injection of [3H] Nle11-SP or [14C] inulin was determined in 18 brain regions and the anterior pituitary of male rats. As compared to the reference [14C] inulin (mean +/- SD: 0.143 +/- 0.009% of the injected radioactivity per g tissue wet weight), the amount of radioactivity was higher after [3H]Nle11-SP injection (0.233 +/- 0.039%, p less than 0.001). Statistically significant differences could be found particularly in cortical and caudal areas as well as in the circumventricular organs studied. These observations do not refute the assumption that a low brain uptake of the labelled neuropeptide occurred due to an accumulation within structures of the blood-brain barrier and/or a penetration of the barrier system.