蛋白多肽类药物鼻黏膜给药直接入脑途径的研究进展

随着生物技术的发展,生物大分子在药学领域中的应用越来越广泛.大量的蛋白多肽类药物用于临床,给药剂学研究带来了新的机遇和挑战.许多蛋白质和多肽类药物均有中枢神经活性,而血脑屏障(blood brain barrier,BBB)的存在,阻碍了这些物质进入中枢神经系统(central nerves system,CNS)和发挥疗效.鼻黏膜给药后药物通过鼻黏膜直接入脑途径,可避开BBB而直接入脑,为蛋白多肽类药物进入脑中发挥疗效提供了一种有效的途径.     

芳香开窍类中药对血脑屏障结构及功能影响的研究进展

目的综述近年来芳香开窍类中药对血脑屏障(BBB)结构及功能的影响,为从中药"芳香开窍"的传统功效中挖掘、筛选、评价和研发创新药物提供文献依据和研究思路。方法对近10年来芳香开窍类中药对血脑屏障结构及功能影响的国内外相关文献进行整理、归纳、分析。结果药理学研究证实芳香开窍类中药主要通过自由透过血脑屏障发挥药效、降低BBB的通透性以保护脑组织以及促进血脑屏障开放三个方面来改变血脑屏障的通透性,另外其作用机制可能与抑制BBB上P-gp的表达和功能有关。结论从P-gp方面加强对芳香开窍类中药作用机制的研究和探索芳香开窍类中药的功效物质基础将是今后研究的重点。     

氨基酸转运体LAT1介导的中枢神经系统药物研究进展

化学药物治疗中枢神经系统(CNS)疾病研究的重大挑战是如何使药物透过血脑屏障(BBB)转运到神经系统中,因为BBB对大部分化学药物来说,是致密而难以通过的屏障。研究发现,BBB上存在许多特殊的转运体系统,用于转运大脑所需营养物质。人们可以把这些转运体作为研究对象,使得药物能够经过这些转运体的介导而透过BBB转运入脑。在这些转运体中氨基酸转运体LAT1(large amino acid transporter-1)逐渐成为了近年来的研究热点,而许多研究也已经证明LAT1在BBB上高表达,本文对LAT1的结构功能、转运调节及表达进行介绍,综述近年来关于LAT1介导的中枢神经系统药物的研究进展,为中枢神经系统药物的设计提供参考。     

芳香开窍药宣通玄府治疗缺血性中风的作用机理探讨

近年来,随着研究的深入,学者们从玄府学说认识缺血性中风与脑缺血再灌注损伤(CIRI),认为中风病存在玄府闭塞、气血不通、神机不遂的病机,脑之玄府闭塞是缺血性中风的发病关键,治疗强调宣通玄府。现代医学研究发现,CIRI后血脑屏障(BBB)通透性改变,具有中枢神经系统(CNS)疾病治疗作用的药物大多不能通过BBB,而芳香开窍药能够双向调控BBB通透性,从而保护脑组织。所以我们通过对芳香开窍药宣通玄府治疗缺血性中风的作用机理的分析,明确了脑之玄府与BBB具有相似性的关系,得出结论是芳香开窍药治疗缺血性中风的作用机理在于该药能够双向调控CIRI后BBB通透性、降低BBB通透性、减轻脑水肿、调节相关蛋白,从而运用现代化的微观指标诠释了玄府理论的实质内涵。     

穿透血脑屏障的抗癌药物靶向治疗：药物的化学修饰或纳米粒方法

治疗中枢神经系统（CNS）疾病药物研发的最大难点是如何使药物通过静脉注射后经血液循环穿透血脑屏障（BBB）分布到CNS。目前,BBB靶向技术的研发非常活跃,其中重要的方法是进行药物分子化学修饰或将药物装载于纳米粒以穿越BBB。本文综述了通过药物的功能性化学修饰、药物载体系统和BBB内源转运子方法实现上述目标。     

基于不同种属细胞体外血脑屏障模型的药物渗透性比较（英文）

血脑屏障(BBB)对维持中枢神经系统(CNS)内环境稳态发挥着重要作用。由于BBB的存在,许多CNS药物难以进入脑组织发挥药效,严重影响CNS疾病的治疗。基于细胞的体外BBB模型是研究CNS药物递送的重要工具。现已开发利用小鼠、大鼠、牛、猪和人的脑内皮细胞用于建立体外BBB模型。然而,由于物种的差异,不同种属来源的体外BBB模型在转运体、受体和紧密连接等蛋白表达上的差异是显著的。本文综述了常用的几种不同种属的体外细胞BBB模型,为研究者选择BBB模型提供参考。     

大剂量应用甲氨蝶呤后用羧肽酶G_2解救治疗

单用甲氨蝶呤(MTX)是最有效的、治疗原发性中枢神经系统淋巴瘤(PCNSL)的药物,部分因为大剂量应用MTX时,它能透过完好的血脑屏障(BBB)。而随后必须用亚叶酸解救MTX的毒性作用对全身器官的损害,特别是骨髓和胃肠道。但是亚叶酸也可能解救肿瘤细胞免除MTX的致死性作用。羧肽酶G2(CPG2)不仅能迅速裂解MTX为谷氨酸和2,4二氨基N10甲基蝶酸(DAMPA),而且不透过BBB,即使BBB的通透性异常时也不透过该细胞膜,因而不会抵消细胞内MTX的作用,所以CPG2有可能替代亚叶酸作为大剂量应用MTX后的解救药。作者对4名复发性PCNSL病人联用大…     

纳米粒穿透血脑屏障机制的研究进展

血脑屏障(blood-brain barrier,BBB)的存在使98%的药物无法进入脑组织,是制约神经系统药物发展的重要因素.纳米粒载药系统能够透过BBB,并提高脑内药物浓度,是实现脑内靶向给药的良好载体,但其透过BBB的机制至今尚未完全明白.自从2001年Kreuter提出关于纳米粒(nanoparticles,NP)透过BBB的6点可能机制后,针对此机制并进而提高载药NP入脑效率的探讨已成为热点之一,文中就目前NP穿透BBB机制研究进展做一综述.     

促进大分子药物跨血脑屏障转运多功能载体的研究进展

血脑屏障(Blood Brain Barrier，BBB)在防止异物入侵，保护脑功能正常方面起着非常重要的作用。促进药物特别是大分子药物跨过BBB入脑是脑疾病药物治疗学和脑药发展的重要研究领域之一。本文就近年促进药物跨BBB转运体系的研究进展作综述性介绍。     

siRNA:脑部药物递送的突破

[英]/FlemmingA∥Nat Rev Drug Discov.-2007,6(8).-601对于治疗中枢神经系统疾病的药物而言,难点之一就是药物难以透过血脑屏障(BBB)。Kumar等在Nature杂志上公布了一种将小干扰RNA(siRNA)靶向递送至中枢神经系统的方法,它不仅提供了一种安全、非创伤性的siRNA脑部递送途径,且为其他药物分子透过BBB带来了希望。为了促进siRNA透过BBB,研究者利用了狂犬病毒进入神经细胞并在整个脑部扩散的机制。从狂犬病毒糖蛋白(rabies virus glycoprotein,RVG)中分离出由29个氨基酸组成的小肽被证明是开启中枢神经系统大门的“钥匙”,这种小…     

Electromagnetic interference in the permeability of saquinavir across the blood-brain barrier using nanoparticulate carriers

Transport of antiretroviral agents across the blood-brain barrier (BBB) is of key importance to the treatment for the acquired immunodeficiency syndrome (AIDS). In this study, impact of exposure to electromagnetic field (EMF) on the permeability of saquinavir (SQV) across BBB was investigated. The in vitro BBB model was based on human brain-microvascular endothelial cells (HBMEC), and the concentration of SQV in receiver chamber of the transport system was evaluated. Polybutylcyanoacrylate (PBCA), methylmethacrylate-sulfopropylmethacrylate (MMA-SPM), and solid lipid nanoparticle (SLN) were employed as carriers for the delivery systems. Cytotoxicity of SLN decreased as content of cacao butter increased. Power of 5mV was apposite for the study on HBMEC without obvious apoptosis. Square wave produced greater permeability than sine and triangle waves. The carrier order on permeability of SQV across HBMEC monolayer under exposure to EMF was SLN>PBCA>MMA-SPM. Also, a larger frequency, modulation or depth of amplitude modulation (AM), or modulation or deviation of frequency modulation (FM) yielded a greater permeability. Besides, enhancement of permeability by AM wave was more significant than that by FM wave. Transport behavior of SQV across BBB was strongly influenced by the combination of nanoparticulate PBCA, MMA-SPM, and SLN with EMF exposure. This combination would be beneficial to the clinical application to the therapy of AIDS and other brain-related diseases.     

神经生长因子脂质体跨血脑屏障体内外研究神经生长因子脂质体跨血脑屏障体内外研究

目的研究神经生长因子（nerve growth factor,NGF）脂质体在体外血脑屏障（blood-brain barrier,BBB）模型上的通透性以及在体内脑组织的分布，并对体内外结果进行相关性分析。方法用小鼠脑微血管内皮细胞(BMVEC)建立的BBB体外实验模型，研究NGF脂质体在体外模型上的通透率；¹²⁵I-NGF和SDS-PAGE法联合使用研究NGF脂质体在脑组织的分布。结果NGF脂质体的最高包封率为34%，平均粒径小于100 nm。脂质体能够增加NGF在BBB模型上的通透率，以NGF-SSL-T为最大。脑组织药物浓度次序为NGF-SSL-T>NGF-SSL+RMP-7>NGF-SSL。体内外结果具有良好相关性。结论脂质体能够增加NGF跨越BBB的能力，RMP-7偶联在脂质体上（NGF-SSL-T）效果好于RMP-7与脂质体的简单混合（NGF-SSL+RMP-7）。     

Methotrexate loaded polyether-copolyester dendrimers for the treatment of gliomas: enhanced efficacy and intratumoral transport capability

Therapeutic benefit in glial tumors is often limited due to low permeability of delivery systems across the blood-brain barrier (BBB), drug resistance, and poor penetration into the tumor tissue. In an attempt to overcome these hurdles, polyether-copolyester (PEPE) dendrimers were evaluated as drug carriers for the treatment of gliomas. Dendrimers were conjugated to d-glucosamine as the ligand for enhancing BBB permeability and tumor targeting. The efficacy of methotrexate (MTX)-loaded dendrimers was established against U87 MG and U 343 MGa cells. Permeability of rhodamine-labeled dendrimers and MTX-loaded dendrimers across the in vitro BBB model and their distribution into avascular human glioma tumor spheroids was also studied. Glucosylated dendrimers were found to be endocytosed in significantly higher amounts than nonglucosylated dendrimers by both the cell lines. IC 50 of MTX after loading in dendrimers was lower than that of the free MTX, suggesting that loading MTX in PEPE dendrimers increased its potency. Similar higher activity of MTX-loaded glucosylated and nonglucosylated dendrimers was found in the reduction of tumor spheroid size. These MTX-loaded dendrimers were able to kill even MTX-resistant cells highlighting their ability to overcome MTX resistance. In addition, the amount of MTX-transported across BBB was three to five times more after loading in the dendrimers. Glucosylation further increased the cumulative permeation of dendrimers across BBB and hence increased the amount of MTX available across it. Glucosylated dendrimers distributed through out the avascular tumor spheroids within 6 h, while nonglucosylated dendrimers could do so in 12 h. The results show that glucosamine can be used as an effective ligand not only for targeting glial tumors but also for enhanced permeability across BBB. Thus, glucosylated PEPE dendrimers can serve as potential delivery system for the treatment of gliomas.     

Comparison of in vitro BBMEC permeability and in vivo CNS uptake by microdialysis sampling

The studies presented in this report were designed to assess the correlation of the bovine brain microvessel endothelial cell (BBMEC) apparent permeability coefficient (P_app) and in vivo BBB penetration using microdialysis sampling. A mathematical model was developed to describe the relationship of brain extracellular fluid (ECF) concentration to free drug in plasma. The compounds studied have a broad range of physico-chemical characteristics and have widely varying in vitro and in vivo permeability across the blood–brain barrier (BBB). BBMEC permeability coefficients vary in magnitude from a low of 0.9×10⁻⁵ cm/s to a high value of 7.5×10⁻⁵ cm/s. Corresponding in vivo measurements of BBB permeability are represented by clearance (CL_in) into the brain ECF and range from a low of 0.023 μl/min/g to a high of 12.9 μl/min/g. While it is apparent that in vitro data from the BBMEC model can be predictive of the in vivo permeability of a compound across the BBB, there are numerous factors both prior to and following entry into the brain which impact the ultimate uptake of a compound. Even in the presence of high BBB permeability, factors such as high plasma protein binding, active efflux across the BBB, and metabolism within the CNS can greatly limit the ultimate concentrations achieved. In addition, concentrations in the intracellular space may not be the same as concentrations in the extracellular space. While these data show that the BBMEC permeability is predictive of the in vivo BBB permeability, the complexity of the living system makes prediction of brain concentrations difficult, based solely on the in vitro measurement.     

Comparison of drug permeabilities across the blood-retinal barrier, blood-aqueous humor barrier, and blood-brain barrier

Drugs vary in their ability to permeate the blood-retinal barrier (BRB), blood-aqueous humor barrier (BAB), and blood-brain barrier (BBB) and the factors affecting the drug permeation remain unclear. In this study, the permeability of various substances across BRB, BAB, and BBB in rats was determined using the brain uptake index (BUI), retinal uptake index (RUI), and aqueous humor uptake index (AHUI) methods. Lipophilic substances showed high permeabilities across BBB and BRB. The RUI values of these substances were approximately four-fold higher than the BUI values. The AHUI versus lipophilicity curve had a parabolic shape with AHUI(max) values at log D(7.4) ranging from -1.0 to 0.0. On the basis of the difference on the lipophilicities, verapamil, quinidine, and digoxin showed lower permeability than predicted from those across BBB and BRB, whereas only digoxin showed a lower permeability across BRB. These low permeabilities were significantly increased by P-glycoprotein inhibitors. Furthermore, anion transporter inhibition increased the absorption of digoxin to permeate into the retina and aqueous humor. In conclusion, this study suggests that efflux transport systems play an important role in the ocular absorption of drugs from the circulating blood after systemic administration.     

Development of a physiologically based pharmacokinetic model for the rat central nervous system and determination of an in vitro-in vivo scaling methodology for the blood-brain barrier permeability of two transporter substrates, morphine and oxycodone

A whole-body physiologically based pharmacokinetic (PBPK) model was developed for the prediction of unbound drug concentration-time profiles in the rat brain, in which drug transfer across the blood–brain barrier (BBB) was treated mechanistically by separating the parameters governing the rate (permeability) of BBB transfer from brain binding. An in vitro–in vivo scaling strategy based on Caco-2 cell permeability was proposed to extrapolate the active transporter-driven component of this permeability, in which a relative activity factor, RAF, was estimated by fitting the model to rat in vivo profiles. This scaling factor could be interpreted as the ratio of transporter activity between the in vitro system and the in vivo BBB, for a given drug in a given in vitro system. Morphine and oxycodone were selected to evaluate this strategy, as substrates of BBB-located efflux and influx transporters, respectively. After estimation of their respective RAFs using the rat model, the PBPK model was used to simulate human brain concentration profiles assuming the same RAF, and the implications of this were discussed. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:4277–4292, 2012     

In vitro models of the blood-brain barrier to polar permeants: comparison of transmonolayer flux measurements and cell uptake kinetics using cultured cerebral capillary endothelial cells.

Given that the cerebral microvasculature within the brain constitutes the rate-limiting barrier to drug entry, primary cultures of cerebral capillary endothelial cells would appear to offer a potentially useful model system for predicting drug delivery to the central nervous system. In the present study, the predictive capabilities of two potential models of the in vivo blood-brain barrier (BBB) to the passive diffusion of polar permeants were assessed. A comparison of the logarithms of the in vitro transmonolayer permeability coefficients (Pmonolayer) for several polar permeants varying in lipophilicity (from this study and literature data) with the well-established relationship between the logarithms of the in vivo BBB permeability coefficients (log PBBB) and permeant lipophilicity as measured by the logarithm of the octanol/water partition coefficient (log PCoctanol/water) demonstrated that in vitro permeation across these monolayers is largely insensitive to polar permeant lipophilicity as a result of the predominance of the paracellular component in the transmonolayer flux. Conversely, kinetic studies of uptake of the same compounds into monolayers yielded transfer rate constants (kp) reflecting membrane permeability coefficients ranging over several orders of magnitude, similar to the variation in permeant lipophilicity. Furthermore, a linear relationship could be demonstrated between the logarithms of kp and in vivo BBB log P (slope = 1.42 +/- 0.35; r = 0. 92). In conclusion, this preliminary investigation suggests that monitoring the kinetics of cell uptake into cerebral capillary endothelial cell monolayers may be superior to transmonolayer flux measurements for predicting the passive diffusion of polar permeants across the BBB in vivo.     

Transport of saquinavir across human brain-microvascular endothelial cells by poly(lactide-co-glycolide) nanoparticles with surface poly-(γ-glutamic acid)

Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) with surface poly-(γ-glutamic acid) (γ-PGA) were applied to enhance the transport of saquinavir (SQV) across the blood-brain barrier (BBB). PLGA NPs encapsulated SQV and grafted with γ-PGA to form drug carriers (γ-PGA/SQV-PLGA NPs) for crossing through a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated with human astrocytes. The results revealed that a lower molecular weight of γ-PGA yielded a higher grafting efficiency of γ-PGA on PLGA NPs. In addition, γ-PGA with a low molecular weight accelerated the dissolution of SQV from γ-PGA/SQV-PLGA NPs. A higher grafting efficiency (more didecyl dimethylammonium bromide) and a lower molecular weight of γ-PGA increased the permeability of SQV across the BBB, in general. When the grafting efficiency was 85.2% at 6 kDa of γ-PGA, γ-PGA/SQV-PLGA NPs reached about 6 times the permeability of free SQV (the maximal permeability). γ-PGA could also promote the endocytosis of NPs and expression of ornithine decarboxylase by HBMECs. γ-PGA/SQV-PLGA NPs are efficacious nanoparticulate carriers in delivering antiretroviral drug across the BBB.     

Effect of nanoparticulate polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate on the permeability of zidovudine and lamivudine across the in vitro blood-brain barrier

Effect of size of nanoscaled polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) on the permeability of zidovudine (AZT) and lamivudine (3TC) across the blood-brain barrier (BBB) was investigated. Also, influence of alcohol on the permeability of AZT and 3TC incorporated with the two polymeric nanoparticles (NPs) was examined. The loading efficiency and the permeability of AZT and 3TC decreased with an increase in the particle size of the two carriers. By employing PBCA NPs, the BBB permeability of AZT and that of 3TC became, respectively, 8-20 and 10-18 folds. Application of MMA-SPM NPs leaded to about 100% increase in the BBB permeability of the two drugs. In the presence of 0.5% ethanol, 4-12% enhancement in the BBB permeability of the two drugs was obtained in the current carrier-mediated system.     

Arecoline, but not haloperidol, induces changes in the permeability of the blood-brain barrier in the rat

The aim of the present study was to investigate the existence of alterations of the blood-brain barrier (BBB) permeability in rats injected with centrally acting drugs, by calculating a unidirectional blood-to-brain transfer constant (Ki) for the circulating tracer [14C]-alpha-aminoisobutyric acid. The intraperitoneal (i.p.) injection of the dopaminergic antagonist haloperidol (1 mg kg-1) did not modify the regional BBB permeability. When the cholinomimetic agent arecoline hydrobromide (6.25 mg kg-1) was injected i.p. into methylatropine-pretreated rats, it induced a significant decrease of Ki values within the frontal cortex, parietal cortex, striatum and brain-stem. Our findings emphasize two concepts: (1) centrally acting drugs, such as arecoline, can induce changes in the BBB permeability, through several mechanisms; (2) there is no predictable correlation of drug stimulation of specific brain neuronal pathways and changes in the permeability of the BBB.