Inhibition by ascorbic acid of NMDA-evoked acetylcholine release in rabbit caudate nucleus

Summary The interaction of ascorbic acid and of dehydroascorbic acid with acetylcholine (ACh) release in rabbit caudate nucleus was investigated. The presence of ascorbic acid in the superfusion medium decreased the release of ACh evoked by N-methyl-d-aspartate (NMDA), but not by electrical stimulation. The pH of the buffer was always maintained at 7.4. Inhibition occurred even at 570 µmol/l ascorbic acid, a concentration which is widely employed in transmitter release experiments. In vivo this concentration may be reached extracellularly in brain tissue. Both ascorbic acid and dehydroascorbic acid inhibited the NMDA-evoked ACh release to the same degree in a non-competitive manner. The nearly identical action of ascorbic acid and dehydroascorbic acid makes a mode of action by lipid peroxidation or by redox phenomena unlikely. The mechanism of action underlying the described effects is unknown. Correspondence to: T .J. Feuerstein at the above address     

Preparation, characterization and evaluation of breviscapine lipid emulsions coated with monooleate-PEG-COOH

Series of monooleate-modified PEG with active carboxylic terminus on the other end (MO-PEG-COOH) were used to modify the lipid emulsions surface to prepare a sterically stabilized lipid emulsions for carrying Traditional Chinese Medicine - breviscapine. Based on the research of relationship between polymer structure and prolonged circulation activity, we developed an optimized formulation and a technological method to prepare the sterile and stable MO-PEG(10,000)-COOH (Bre-LE-PEG(10,000)) coated breviscapine lipid emulsions (Bre-LE) for intravenous administration. Follow the optimum preparation, the average particle size, polydispersity index, zeta potential, Ke value and content of final product were determined to be (207.1±8.5)nm, 0.197±0.005, (-33.6±2.0)mV, (21.1±2.3)% and (95.0±1.8)% respectively (n=3). The characteristics, stability and safety of Bre-LE-PEG(10,000) were also studied with Bre-LE as a control. Increased plasma concentration by surface modification of the lipid emulsions may enhance the pharmacological activity of breviscapine to promote blood circulation.     

水飞蓟宾脂肪乳的制备、性质及体外释药研究

目的：制备水飞蓟宾脂肪乳并对其体外释放进行考察。方法：在单因素试验的基础上,采用正交试验设计优化水飞蓟宾脂肪乳处方。采用高压均质法制备水飞蓟宾脂肪乳。结果：脂肪乳平均粒径为（74.42±14） nm,粒径分布系数（ PDI）为0.106,Zeta电位为（-30.2±2.13）mV,pH为6.48±0.04,包封率（91.45±0.0052）%,体外12 h内,累积释放原药的90%左右。结论：本试验获得了较理想的水飞蓟宾脂肪乳,其体外释放具有显著的缓释作用。     

Lipid microspheres (lipid emulsions) as a drug carrier — An overview

Although the Drug Delivery System (DDS) concept is not new, great progress has recently been made in the treatment of a variety of diseases. Targeting delivery of drugs to the diseased lesions is one of the most important aspects of DDS. To convey a sufficient dose of drugs to the lesion, suitable carriers of drugs are needed. Lipid microspheres (lipid emulsion) have been developed, mainly in Japan, as excellent carriers of drugs. This article presents an overview of lipid microsphere technology as a drug carrier.     

Lipid nano/submicron emulsions as vehicles for topical flurbiprofen delivery

The application of lipid nano/submicron emulsions as topical drug carrier systems for the percutaneous absorption of flurbiprofen was investigated. The lipid emulsions were made up of isopropyl myristate (IPM), soybean oil, or coconut oil as the oil phase, egg lecithin as the predominant emulsifier, and double-distilled water as the external phase. Stearylamine (SA) and deoxycholic acid (DA) also were used to produce positively and negatively charged emulsions. To evaluate the physicochemical properties of the lipid emulsions, particle size by laser light scattering, the image of atomic force microscopy, and relaxation time values by Nuclear Magnetic Resonance (NMR) were determined. The in vitro permeation data showed that incorporation of SA significantly reduced the topical delivery of flurbiprofen. On the other hand, incorporation of DA exhibited no or a negligible effect on drug permeation. Enhancement of drug absorption was observed when adding oleic acid as part of the oil phase. The in vivo topical application of flurbiprofen from selected lipid emulsions showed a similar trend to the in vitro status. Furthermore, the intersubject variability was considerably reduced by lipid emulsions than by aqueous suspensions in both the in vitro and in vivo experiments. The irritant profiles of lipid emulsions showed that IPM elicited higher irritation than soybean oil. The incorporation of oleic acid also produced skin disruption. The results in the present study suggest the feasibility of lipid emulsions for the topical delivery of flurbiprofen.     

络合沉淀-紫外分光光度法测定黄芩素脂肪乳中甲氧基苯胺值

目的：建立一种专属性好适用于主药有干扰的脂肪乳中甲氧基苯胺值的测定方法。方法：以醋酸铅为络合沉淀剂,采用络合沉淀法排除主药黄芩素对甲氧基苯胺值测定的影响,并对改进后的方法进行验证分析;结果：方法中选择加入沉淀剂的量为200μL,专属性良好,干扰试验结果为99.39%,RSD为1.73%(n=3),重复性结果RSD均小于5.0%(n=5)。结论：该方法专属性好,测定结果准确可靠,能有效排除药物对脂肪乳甲氧基苯胺值测定影响,扩大了甲氧基苯胺值紫外分光光度测定法的适用性,为载药脂肪乳中甲氧基苯胺值控制提供了新的思路和方法。     

Ethanol inhibits the N-methyl-D-aspartate (NMDA)-induced attenuation of the NMDA-evoked noradrenaline release in the rat brain cortex: interaction with NMDA-induced desensitization

Summary The influence of ethanol, AP5 (DL-2-amino-5-phosphonopentanoic acid) and dizocilpine (MK-801) ((+)-5-methyl-10, 11-dihydro-5H-dibenzo (a, b)-cyclohept-5,10-imine hydrogen maleate) on the NMDA-induced attenuation of the NMDA-evoked noradrenaline release was examined in rat brain cortex slices preincubated with ³H-noradrenaline. The slices were superfused with Mg²⁺-free Krebs-Henseleit solution. Tritium overflow (corresponding to ³H-noradrenaline release) was stimulated by 300 mol/l NMDA for 2 min.Presence of 10–100 mol/l NMDA from 20 to 2 min before stimulation concentration-dependently inhibited the NMDA (300 mol/l)-evoked ³H overflow, suggesting an agonist-induced desensitization attributable to the modification of events at the NMDA receptor itself and/or distal to this receptor system. The desensitizing effect of 100 mol/l NMDA was almost complete and was not diminished when the time of preexposure was decreased to 10 min, and when NMDA was removed from the superfusion fluid for up to 5 min before the stimulus; however, the densitizing effect was reduced after further decrease in the duration of preexposure to NMDA or further prolongation of the interval between preexposure and stimulation. Ethanol inhibited the NMDA-induced ³H overflow (IC₅₀ 45 mmol/l); this effect was almost abolished when ethanol was omitted from the superfusion fluid from 2 min before stimulation onward. Ethanol, when simultaneously present with 100 mol/l NMDA in the superfusion fluid from 20 to 2 min before the NMDA stimulus, concentration-dependently (IC₅₀ 112 mol/l) decreased the inhibitory effect of NMDA. The effect of ethanol was identical to that of the competitive NMDA receptor antagonist AP5 both with respect to the rapid reversibility of the inhibition of NMDA induced ³H overflow (i.e. within 2 min) and to the decrease of the desensitizing effect of NMDA. The pattern of effects obtained with dizocilpine, an inhibitor of the ion channel coupled to the NMDA receptor, was different from that obtained with ethanol and AP5: the inhibitory effect of dizocilpine on the NMDA-evoked ³H overflow was only partly reversible within 8 min after withdrawal, and the inhibitory effect of NMDA on NMDA-evoked ³H overflow was not decreased by dizocilpine, but was more pronounced than with either NMDA or dizocilpine alone.It is concluded that ethanol mimics AP5 in that in inhibits the NMDA induced desensitization, possibly by preventing the NMDA receptor from being activated by NMDA applied during the desensitization period. In contrast, dizocilpine produces no such effect. The potency of ethanol in inhibiting the NMDA-induced desensitization was about 3 times less than in inhibiting NMDA-evoked noradrenaline release. These results are compatible with the suggestion that the NMDA recognition site itself may be one of the sites of action of ethanol and that ethanol does not modify the function of the NMDA receptor system by a machanism comparable to that of dizocilpine. Send offprint requests to M. Göthert at the above address     

Effect of Oxyethylene Moieties in Hydrogenated Castor Oil on the Pharmacokinetics of Menatetrenone Incorporated in O/W Lipid Emulsions Prepared with Hydrogenated Castor Oil and Soybean Oil in Rats

Lipid emulsions with particle sizes of 190–270 nm were prepared with soybean oil (SO) and a series of hydrogenated castor oils (HCOs) with various oxyethylene numbers, and the effect of oxyethylene numbers of HCOs on the pharmacokinetics of menatetrenone incorporated into the lipid emulsions was studied in rats. Plasma half-life of menatetrenone after administration as the lipid emulsions prepared by HCO with 10 oxyethylene units (SO/HCO10) was similar to that after the administration as SO/egg yolk phosphatides (SO/EYP), but was shorter than that as the lipid emulsions prepared by HCOs with >20 oxyethylene units (SO/HCO20, SO/HCO30, SO/HCO60 and SO/HCO100). Menatetrenone incorporated in SO/HCO10, SO/HCO20 and SO/HCO60 was not taken up by the blood cells in vitro, and the plasma level of menatetrenone incorporated in SO/HCO10 was similar to that of triglycerides, suggesting that menatetrenone was not released from the oil particles even after entering the circulation. Menatetrenone uptake by the liver for SO/HCO10 was similar to that for SO/EYP, while those for SO/HCO20, SO/HCO30, SO/HCO60 and SO/HCO100 was less than that for SO/EYP. These findings clearly demonstrate that 20 oxyethylene units in HCOs is the minimum requirement for the prolongation of the plasma circulation time of menatetrenone incorporated in SO/HCOs.     

Inhibition by sigma receptor ligand, MS-377, of N-methyl-D-aspartate-induced currents in dopamine neurons of the rat ventral tegmental area

RATIONALE: MS-377 [( R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl) piperazin-1-yl]methyl-2-pyrrolidinone L-tartrate] is a novel anti-psychotic drug candidate with high affinity for sigma receptors but devoid of binding affinity for PCP binding site of NMDA receptor/ion channel complex. OBJECTIVES: The effects of MS-377 on NMDA receptor and/or its ion channel complex were examined to elucidate the antipsychotic properties of MS-377. METHODS: We examined the effect of MS-377 on NMDA ( N-methyl- D-aspartate)-induced current in acutely dissociated dopamine neurons of rat ventral tegmental area (VTA) using patch clamp whole cell recording. RESULTS: MS-377 applied in a bath inhibited the peak current evoked by NMDA applied via the U-tube method for 2 s in a concentration-dependent manner. Other sigma receptor ligands, BD-1063 (1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine), NE-100 ( N, N-dipropyl-2-[4-methoxy-3-(2-phenylenoxy)-phenyl]-ethylamine monohydrochloride) and haloperidol also inhibited NMDA-induced current in a concentration-dependent manner. Interestingly, concomitant application of MS-377 with BD-1063, NE-100 or haloperidol at concentrations that had no effects on NMDA-induced current, potentiated the MS-377-induced inhibition. CONCLUSIONS: The results suggest that MS-377, as well as other sigma receptor ligands, indirectly acts on the sigma receptor to inhibit glutaminergic transmission mediated by NMDA receptor/ion channel complex in VTA dopamine neurons, thereby inhibiting dopamine release in target VTA areas.     

载药脂肪乳注射液的研究进展

目的介绍载药脂肪乳注射液作为一种新型药物载体,在药学中的研究进展。方法参阅国内外相关文献29篇,进行分析、整理、归纳和总结。结果阐述了近几年来其制备材料和工艺、质量评价体系、临床应用范围的研究情况,并对未来的发展前景进行了综述。结论载药脂肪乳注射液具有较好的开发前景和临床应用价值。     

Paraquat detoxication with multiple emulsions

In this study, we show that detoxifying W/O/W multiple emulsions, prepared with an appropriate extractant/trapping couple, represent a promising technology for quick and safe poisoning treatments, with application to the highly toxic herbicide Paraquat, responsible of poisonings from low-dose exposure leading to several deaths every year. In vitro tests led to the choice of an appropriate extractant/trapping couple system with significant detoxication performance. In vivo tests showed (i) that rats receiving high doses of Paraquat, then a detoxifying emulsion, presented an increase from 50% to 100% of the MST (median survival time) and (ii) that no mortality was observed during 30 days with rats dosed with emulsions initially loaded with Paraquat at a concentration much higher than the lethal dose, proving the stability and the inocuity of the detoxifying multiple emulsion in the gastrointestinal tract.     

顺铂静脉注射乳剂的制备及其性质考察

目的:制备顺铂静脉注射乳剂并对其性质进行考察。方法:通过正交设计优选了顺铂乳剂的最佳处方及其制备工艺,并通过粒径、ζ电位、pH值的测定和稳定性的考察初步研究了顺铂乳剂的一些基本性质。结果:顺铂乳剂的最佳处方为磷脂0.9%,泊洛沙姆-1882%和油酸0.2%,制备温度为70℃。所制备的乳剂平均粒径为144nm,ζ电位为-29.8mV。稳定性实验表明乳剂在高温灭菌、长期稳定性试验中粒径、pH值和含量无明显的变化。结论:本实验制备的顺铂乳剂粒径分布较窄,稳定性较好。     

Toluene exposure during brain growth spurt and adolescence produces differential effects on N-methyl-D-aspartate receptor-mediated currents in rat hippocampus

Toluene, an industrial organic solvent, is voluntarily inhaled as drug of abuse. Because inhibition of N-methyl-d-aspartate (NMDA) receptors is one of the possible mechanisms underlying developmental neurotoxicity of toluene, the purpose of the present study was to examine the effects of toluene exposure during two major neurodevelopmental stages, brain growth spurt and adolescence, on NMDA receptor-mediated current. Rats were administered with toluene (500 mg/kg, i.p.) or corn oil daily over postnatal days (PN) 4-9 (brain growth spurt) or PN 21-26 (early adolescence). Intracellular electrophysiological recordings employing in CA1 pyramidal neurons in the hippocampal slices were performed during PN 30-38. Toluene exposure during brain growth spurt enhanced NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) by electrical stimulation, but impaired the paired-pulse facilitation and NMDA response by exogenous application of NMDA. Toluene exposure during adolescence resulted in an increase in NMDA receptor-mediated EPSCs and a decrease in exogenous NMDA-induced currents, while lack of any effect on paired-pulse facilitation. These findings suggest that toluene exposure during brain growth spurt and adolescence might result in an increase in synaptic NMDA receptor responsiveness and a decrease in extrasynaptic NMDA receptor responsiveness, while only toluene exposure during brain growth spurt can produce presynaptic modulation in CA1 pyramidal neurons. The functional changes in NMDA receptor-mediated transmission underlying developmental toluene exposure may lead to the neurobehavioral disturbances.     

子痫前期患者循环内皮细胞数量和血脂水平变化及临床意义

目的探讨血清中循环内皮细胞（CEC）个数和血脂水平变化与子痫前期（PE）发病及病情轻重程度的相关性。方法选取60例PE患者作为试验组,健康孕晚期妇女40例作为对照组。分别检测2组受试者血清CEC个数和血脂变化情况。结果试验组血中CEC个数为（17.64±5.16）×105个/L显著高于对照组的（12.91±4.21）×105个/L,差异有统计学意义（P〈0.01）;其中重度PE亚组血中CEC个数[（19.51±5.71）×105个/L]和轻度PE亚组CEC个数（15.77±3.89）×105个/L均高于对照组（P〈0.05）,且重度PE亚组亦高于轻度PE亚组（P〈0.05）。试验组血清三酰甘油（TG）及重度PE亚组低密度脂蛋白胆固醇（LDL-C）均高于对照组,差异有统计学意义（P〈0.05）;试验组高密度脂蛋白胆固醇（HDL-C）低于对照组,差异有统计学意义（P〈0.05）。且重度PE亚组TG水平高于轻度PE亚组,差异有统计学意义（P〈0.05）。结论 CEC数量、脂蛋白与PE发病及病情轻重程度有关。PE患者血脂值结合CEC数量可作为预测PE病情严重程度的参考指标。     

药用静脉注射乳剂的研究进展

目的:介绍药用静脉注射乳剂的种类和主要作用,重点介绍药物的种类、作用特点及开发动态。方法:以国内外相关文献为基础进行分析和归纳。结果:药用静脉注射乳剂提高了药物的靶向性和缓释作用,增加了脂肪乳剂的应用范围。结论:药用静脉注射乳剂具有重要的实用价值和应用前景。     

Biodistribution characteristics of mannosylated and fucosylated O/W emulsions in mice

Cell-specific drug delivery is one of the most promising strategies for improving therapeutic efficiency and minimizing systemic toxicity. Carrier systems devoted to receptor-mediated targeting need to be developed. In the case of liver-non-parenchymal cell-specific targeting systems, glycosylated emulsions have been developed as carriers for lipophilic drugs and/or peptides. This present study demonstrates the in vivo disposition behaviour and pharmacokinetic characteristics of mannosylated (Man-) and fucosylated (Fuc-) emulsions incorporated with cholesten-5-yloxy-N-(4-((1-imino-2-d-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and its fucosylated derivatives (Fuc-C4-Chol), respectively. Man- (or Fuc-) emulsions are composed of soybean oil, EggPC and Man-C4-Chol (or Fuc-C4-Chol) in a weight ratio of 70:25:5. After intravenous administration to mice, these two types of [³H]cholesteryl hexadecyl ether (CHE)-labelled glycosylated emulsions were rapidly eliminated from the blood circulation and preferentially recovered in the liver. In contrast, bare (Bare-) emulsions composed of soybean oil:EggPC:cholesterol (Chol) in a weight ratio of 70:25:5 were more retained in the blood circulation. The hepatic uptake clearances of Man- and Fuc-emulsions were 3.3- and 4.0-times greater than that of Bare-emulsions. Interestingly, the hepatic uptake clearance of Fuc-emulsions was significantly higher that that of Man-emulsions. The uptake ratios by non-parenchymal cells (NPC) and parenchymal cells (PC) (NPC/PC ratio) for Bare-, Man- and Fuc-emulsions were found to be 0.4, 2.0 and 2.9, respectively. The hepatic uptakes of [³H]CHE-labelled Man- and Fuc-emulsions were reduced by pre-dosing with glycosylated proteins and liposomes. These results clearly support the conclusion that Man- and Fuc-emulsions are promising carrier systems for liver NPC-specific targeting via receptor-mediated mechanism.     

Lipid raft: A floating island of death or survival

Lipid rafts are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in the initiation of many pharmacological agent-induced signaling pathways and toxicological effects. The structure of lipid rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, as a major component of lipid rafts, is critical for the formation and configuration of lipid raft microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in lipid raft disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. Several anti-cancer drugs are able to suppress growth and induce apoptosis of tumor cells through alteration of lipid raft contents via disrupting lipid raft integrity.     

口服干乳剂研究进展

干乳剂是新型的药物载体传递系统，理化稳定性好，再分散性好，能显著改善难溶性药物的溶出，增加体外释放，促进肠吸收，提高口服生物利用度。对近年来国外文献以喷雾干燥法制备干乳剂的最新研究进展，该文做了主要概述，表明喷雾干燥乳剂作为一种含油的粉末制剂，其应用前景广阔。     

Adenosine A2A receptors inhibit the N-methyl-D-aspartate component of excitatory synaptic currents in rat striatal neurons

The effects of the adenosine A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethyl-amino-5'-N-ethylcarboxamidoadenosine (CGS 21680) on currents mediated by excitatory amino acid receptors were examined in rat striatal brain slices. In a Mg(2+)-free superfusion medium, CGS 21680 decreased the amplitude of excitatory postsynaptic currents (EPSCs) in about 70% of striatal neurons. The inhibitory effect of CGS 21680 disappeared both in the presence of the adenosine A(2A) receptor antagonist 8-(3-chlorostyryl) caffeine and the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP-5). NMDA-induced currents were also depressed by CGS 21680 in a subset of striatal cells, whereas alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-induced currents were not affected. The results suggest that adenosine A(2A) receptor agonists inhibit the NMDA component of the EPSC.     

Rheology and stability of water-in-oil-in-water multiple emulsions containing Span 83 and Tween 80

Multiple emulsions are often stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of these surfactants is important in achieving stable multiple emulsions. The objective of this study was to evaluate the long-term stability of water-in-oil-in-water (W/O/W) multiple emulsions with respect to the concentrations of Span 83 and Tween 80. In addition, the effect of surfactant and electrolyte concentration on emulsion bulk rheological properties was investigated. Light microscopy, creaming volume, and rheological properties were used to assess emulsion stability. It was observed that the optimal surfactant concentrations for W/O/W emulsion long-term stability were 20% wt/vol Span 83 in the oil phase and 0.1% wt/vol Tween 80 in the continuous phase. Higher concentrations of Tween 80 had a destructive effect on W/O/W emulsion stability, which correlated with the observation that interfacial film strength at the oil/water interface decreased as the Tween 80 concentration increased. High Span 83 concentrations increased the storage modulus G′ (solidlike) values and hence enhanced multiple emulsion stability. However, when 30% wt/vol Span 83 was incorporated, the viscosity of the primary W/O emulsion increased considerably and the emulsion droplets lost their shape. Salt added to the inner aqueous phase exerted an osmotic pressure that caused diffusion of water into the inner aqueous phase and increased W/O/W emulsion viscosity through an increase in the volume fraction of the primary W/O emulsion. This type of viscosity increase imposed a destabilizing effect because of the likelihood of rupture of the inner and multiple droplets.