金黄色葡萄球菌与烟曲霉生长最低水分活度的研究

目的 探讨使用葡萄糖、甘油、氯化钠3种介质调节不同水分活度的生长环境对金黄色葡萄球菌及烟曲霉生长的影响。方法 分别加入3种不同的介质控制胰酪大豆胨液体（TSB）培养基、沙氏葡萄糖琼脂（SDA）培养基的水分活度,通过定时对金黄色葡萄球菌进行平板计数、烟曲霉的菌落生长直径测量,判定微生物生长的最低水分活度。结果 金黄色葡萄球菌在甘油与氯化钠调节的水分活度环境下,菌落数均呈下降趋势;在蔗糖介质调节水分活度为0.85,0.86时,菌落数在初始值上下波动,基本维持不变;调节水分活度为0.87时,菌落数在略减后迅速增加。烟曲霉在3种介质调节的所有水分活度环境下,均处于生长停滞状态。结论 环境水分活度的高低对金黄色葡萄球菌、烟曲霉的生长有一定影响。金黄色葡萄球菌在蔗糖介质中的生长最低水分活度近似为0.86,烟曲霉生长最低水分活度>0.83。金黄色葡萄球菌在甘油与氯化钠基质,烟曲霉在3种基质中的最低水分活度与美国药典中收录的最低水分活度值并不相符。     

Antifungal Activity of Leaves of Mangroves Plant Acanthus licifolius Against Aspergillus fumigatus

The antifungal activity of chloroform extract of leaves of Acanthus ilicifolius was evaluated in Aspergillus fumigatus infected mice. Swiss albino mice (60) were divided into five groups. All the groups were immunosuppressed with cyclophosphamide and cortisone acetate couple of days prior to intranasal inoculation with Aspergillus fumigatus conidia (10⁶) in all the groups, except the first. Treatment was initiated at 24 h of fungal inoculation and continued up to day 14, and included amphotericin B (1 mg/kg orally) for group III and extract of Acanthus ilicifolius at 250 mg and 500 mg/kg for group IV and V, respectively. Groups I and II received sterile water orally for the same period. From each group, three mice were sacrificed after 1 h and the remaining mice on the 14^th day of inoculation. One hour post-inoculation lung colony forming unit count confirmed the delivery of conidia into the lungs. Colony forming unit count, intensity of gross necropsy changes and histopathological changes were highest in group II. It improved in group III and also in groups IV and V in dose-dependent manner. Lesions were absent in the noninfected group. Lesions included maximum granulomatous inflammation of lung, multifocal diffused necrotic granulomas on kidney and moderate microgranulomas on liver. From this study, it was concluded that chloroform extract of Acanthus ilicifolius contains active principles that are absorbed after oral administration to produce systemic effects when given at 500 mg/kg dose.     

Biodistribution of Amphotericin B When Delivered Through Cholesterol Hemisuccinate Vesicles in Normal and A. Fumigatus Infected Mice

Purpose. This study compared the biodistribution of two amphotericin B formulations in normal and Aspergillus infected mice. Amphotericin B cholesterol hemisuccinate vesicles (ABCV) which reduces the toxicity of amphotericin B and thereby enhances its therapeutic efficacy in a murine model of aspergillosis was compared with conventional amphotericin B deoxycholate suspension (AmB_DOC). Methods. ABCV (12 mg/kg wt) and AmB_DOC (2 mg/kg wt) were intravenously administered to normal and A.fumigatus infected mice. The concentration of amphotericin B in plasma and other organs was determined at different time points. Results. It was observed that ABCV had a significantly different pharmacokinetic profile compared to conventional amphotericin B. In comparison to AmB_DOC significantly lower levels of amphotericin B were observed in kidneys and plasma, the major target organs of toxicity. Animals receiving ABCV demonstrated high levels of amphotericin B in liver (38% retention till 48 h) and spleen (2.6% retention till 48 h) in comparison to AmB_DOC (7.3% and 0.21% retention in liver and spleen respectively till 48 h). Biodistribution studies of ABCV in infected mice demonstrated that there was a moderate enhancement in levels of amphotericin B in liver, spleen, lungs and kidneys as compared to normal mice and the plasma levels were reduced. However, such observations were not made after AmB_DOC administration to infected mice except for kidneys in which there was a marked increase in uptake as compared to normal mice. Conclusions. Our results suggest that prolonged retention of high concentrations of ABCV in reticuloendothelial system organs is the reason for its reduced toxicity. Enhanced localization of the drug at the infected site may lead to improvement in therapeutic efficacy.     

Antifungal Treatments Delineate a Correlation between Cathepsins and Cytokines in Murine Model of Invasive Aspergillosis

In the pathogenesis of invasive pulmonary aspergillosis both fungal and host factors play roles. Though cytokines and phagocyte, as host factors, have been shown to participate in defence against Aspergillus species yet the role of cysteine proteases, that is cathepsins, a lysosomal enzymes of phagocytes, remains unknown in fungal infection. Studies are available which shows that cytokines regulate the cysteine proteases processed immune molecules for their further action but their relationship with each other under fungal infection is not clear. Therefore, in this study, we demonstrate the substantial role of cathepsins and cytokines in aspergillosis. In the present murine model of invasive pulmonary aspergillosis, on seventh day of Aspergillus fumigatus infection, both kidney and liver showed significant (P<0.05) fungal burdens, which was also confirmed by histological analyses. The activity profiles of four cathepsins in the kidney and liver tissue were analysed and correlated with blood cytokines level in the presence and absence of antifungal compounds (amphotericin B, a standard drug and 2-(3,4-dimethyl-2,5-dihydro-1H-pyrrole-2-yl)-1-methylethyl pentanoate, isolated in our laboratory from natural source) treatment. The data illustrate that the reduction in fungal load in both organs probably results in a decreased local inflammatory response, as measured by decreased levels of interleukin-4 and interleukin-10 and increased level of interferon gamma in the antifungal compounds treated mice. Interestingly, this altered level of cytokines relates well with the activity level of cathepsins, that is decreased in interleukines (interleukinL-4/interleukin-10) and cathepsins (cathepsin B, cathepsin C and cathepsin L); and increase in interferon gamma and cathepsin H levels in the mice treated with antifungal compounds were observed. These observations support not only the negative (cathepsin B, cathepsin C and cathepsin L) and positive (cathepsin H) role of cathepsins in aspergillosis but also prove the role of cytokines in remodelling of immune response. Overall, the study reveals a correlation between cathepsins and cytokines and their regulatory role in fungal mediated infection.     

Comparative Tissue Distribution and Elimination of Amphotericin B Colloidal Dispersion (Amphocil®) and Fungizone® After Repeated Dosing in Rats

The pharmacokinetic profiles of amphotericin B (AmB) after administration of Amphocil^®, an AmB/cholesteryl sulfate colloidal dispersion (ABCD) and the micellar AmB/deoxycholate (Fungizone^®) were compared after repeated dosing in rats. After administration of ABCD and Fungizone at an equal AmB dose (1 mg/kg), AmB concentrations in plasma and most tissues were lower for the ABCD dose, especially in the kidneys where reduced drug concentration correlated with reduced nephrotoxicity. In contrast, AmB concentrations in the liver were substantially higher when ABCD was administered; however, without an accompanying increase in hepato-toxicity. Daily administration of ABCD for 14 days did not lead to AmB accumulation in plasma; while a slight accumulation was observed after multiple administration of Fungizone. AmB was eliminated more slowly from the plasma and various tissues and urinary and fecal recoveries of AmB were reduced after ABCD administration. These results suggest that ABCD may be stored in tissues in a form that is less toxic and is eliminated from the systemic circulation by a different mechanism than the free and protein-bound AmB in plasma. AmB accumulation in the spleen was observed when higher doses of ABCD (5 mg/kg) were administered, which could be due to saturation of hepatic uptake of AmB. Comparison of spleen concentrations of AmB between ABCD and Fungizone^® at 5 mg/kg AmB doses was not possible because of Fungizone's toxicity in rats. In all other organs, AmB concentrations reached or approached a steady state within two weeks of dosing with ABCD. Urinary and fecal clearances of AmB were not different between ABCD and Fungizone administration. In summary, the distribution and elimination characteristics of AmB in rats were substantially altered when it was administered as ABCD in comparison to Fungizone. Nephrotoxicity of AmB in rats was reduced after administration of ABCD apparently because of the altered tissue distribution pattern. Thus, ABCD (Amphocil^®) may be a clinically beneficial formulation of AmB in patients with systemic fungal infections.     

Enhanced Encapsulation of Amphotericin B into Liposomes by Complex Formation with Polyethylene Glycol Derivatives

Purpose. A highly efficient method was developed for the encapsulation of amphotericin B (AmB) in liposomes, and the mechanism involved was characterized. Methods. AmB was encapsulated in dipalmitoylphosphatidylcholine/cholesterol (DPPC/CH, 2:1) liposomes after complex formation with distearoyl-N-(monomethoxy poly(ethylene glycol) succinyl) phosphatidylethanolamine (DSPE-PEG). Hydration of lipids was done with 9% sucrose solution. Results. The encapsulated amount of AmB was 111 g/mg lipid, which was much higher than that obtained by the same method without DSPE-PEG (14 g/mg lipid). The amount encapsulated increased with amount of DSPE-PEG used and with PEG molecular weight. Encapsulation efficacy was also influenced by the type of PEG derivatives used and by the modification of AmB, suggesting the involvement of complex formation between AmB and DSPE-PEG. Absorption and ³¹P-NMR spectral analyses indicated that interactions between the amino and phosphate groups and between the polyene and PEG moieties in AmB and DSPE-PEG, respectively, play an important role in the complex formation. Conclusions. Complex formation of AmB with DSPE-PEG allows the highly efficient encapsulation of the drug in liposomes. This simple technique should be applicable to other hydrophobic drugs.     

Decreased Transport of p-Aminohippurate in Renal Basolateral Membranes Isolated from Rats with Acute Renal Failure

Transport of D-glucose, p-aminohippurate (organic anion), and tetraethylammonium (organic cation) was studied in the renal basolateral membrane vesicles isolated from rats with acute renal failure (ARF). ARF was induced by a single injection of uranyl nitrate. Carrier-mediated transport of p-aminohippurate, estimated under anion–anion exchange condition, was significantly decreased in basolateral membrane vesicles isolated from ARF rats. In contrast, there were no significant differences in D-glucose and tetraethylammonium uptake between normal and ARF rats. When normal basolateral membrane vesicles were incubated in vitro with uranyl nitrate, no significant inhibition in p-aminohippurate uptake was observed. These results suggest that organic anion transport is decreased in renal basolateral membranes from ARF rats, and this transport dysfunction cannot be explained by the direct interaction of uranyl nitrate with the organic anion carrier.     

Hepatoprotective Activity of Xanthones and Xanthonolignoids Against tert-Butylhydroperoxide-Induced Toxicity in Isolated Rat Hepatocytes—Comparison with Silybin

Purpose. Synthesize and evaluate the protective activity against tert-butylhydroperoxide-induced toxicity in freshly isolated rat hepatocytes of trans-kielcorin, trans-isokielcorin B, as well as their respective building blocks 3,4-dihydroxy-2-methoxyxanthone and 2,3-dihydroxy-4-methoxyxanthone. Methods. Wistar rats, weighing 200-250g were used. Hepatocyte isolation was performed by collagenase perfusion. Incubations were performed at 37°C, using 1 million cells per milliliter in modified Krebs—Henseleit buffer. The protective activity was evaluated by measuring reduced and oxidized glutathione, lipid peroxidation and cell viability after inducing toxicity with tert-butylhydroperoxide (1.0 mM, 30 min), with or without the studied compounds in the concentrations of 0.025, 0.050, 0.100 and 0.200 mM. Silybin was tested in the same experimental conditions to serve as a positive control. Results. Using these concentrations, the tested compounds prevented tert-butylhydroperoxide-induced lipid peroxidation and cell death in freshly isolated rat hepatocytes. All compounds were also effective in preventing perturbation of cell glutathione homeostasis in some extent. 3,4-Dihydroxy-2-methoxyxanthone and 2,3-dihydroxy-4-methoxyxanthone were more effective than trans-kielcorin and trans-isokielcorin B respectively. Silybin was less effective in protecting cells against lipid peroxidation and loss of cell viability than the four xanthonic derivatives. Conclusions. The tested compounds protected the freshly isolated rat hepatocytes against tert-butylhydroperoxide-induced toxicity.     

肾移植患者SLCO1B3基因多态性与他克莫司血药浓度相关性研究

目的 探究肾移植患者SLCO1B3基因多态性与术后早期他克莫司血药浓度的相关性。方法 选取昆明市第一人民医院68例肾移植患者为研究对象,运用化学免疫发光法监测他克莫司血药浓度,同时采用聚合酶链反应法检测CYP3A5^*3、SLCO1B3 T334G和G699A基因多态性,并进行基因分型,分析各基因型与他克莫司血药浓度的相关性。结果 CYP3A5^*3不同基因型对术后他克莫司血药浓度和标准化血药浓度有影响,差异具有统计学意义(P＜0.05),SLCO1B3 T334G和G699A基因位点不同基因型对术后他克莫司血药浓度和标准化血药浓度无影响,差异均无统计学意义。结论 与CYP3A5^*3/^*3基因型相比,CYP3A5^*1等位基因携带者达到相同的他克莫司浓度需要增加他克莫司给药剂量。SLCO1B3 T334G和G699A基因多态性对肾移植术后早期他克莫司血药浓度无影响。     

Excipient Interaction with Cetylpyridinium Chloride Activity in Tablet Based Lozenges

Purpose. The purpose of the investigation was to determine the effect of tablet excipients on the activity of cetylpyridinium chloride (CPC) and the relative interaction between excipients and CPC. Methods. An analytical assay was developed to evaluate the interaction between CPC and the excipients. In vivo activity was investigated using six volunteers by determining the reduction in colony forming units recoverable from the oropharynx after sucking each proprietary lozenge separately on different days. In vitro determinations investigated the relative antimicrobial activity of aqueous solutions of the lozenges and, the effect of pH and tablet base excipients on that activity against Staphylococcus aureus, Streptococcus pyogenes and Candida albicans. Results. Both in vivo and in vitro results showed that the tablet based lozenges had markedly reduced antimicrobial activities compared with previous results with a candy based lozenge (in vivo and in vitro) or the same concentration of aqueous CPC (in vitro}. Magnesium stearate suspensions in CPC 250 µg/ml indicated that magnesium stearate adsorbed CPC and at 0.4% lozenge weight and above significantly reduced the antimicrobial activity of CPC 250 µg/ml. Conclusions. The reduced activity of CPC in tablet based lozenges resulted from a decreased availability of CPC in solution due to an adsorption of CPC on magnesium stearate. To avoid this reduction in activity tablet based lozenges containing CPC 250 µg/ml, or similar concentrations, plus magnesium stearate should contain not more than 0.3% w/w lozenge weight of the lubricant.     

Antiinflammatory Activity of Aqueous Extract of Stereospermum kunthianum (Cham, Sandrine Petit) Stem Bark in Rats

Stereospermum kunthianum, Cham, Sandrine Petit (family: Bignoniaceae) is used in traditional medicine to treat bronchitis, pneumonia and coughs, gastritis, wounds, rheumatic arthritis, ulcers, dysentery, leprosy and venereal diseases in humans. The antiinflammatory activity of the aqueous extract of the stem bark was investigated with experimental animal models using the carrageenan-induced paw oedema, leucocytes migration and granuloma air pouch tests in rats. The extract (100, 200 or 400 mg/kg) at 3 h post-treatment caused a significant (p<0.05) reduction in the paw oedema in rats. The effect of the extract was most pronounced at the dose of 400 mg/kg and was higher than that of indomethacin (10 mg/kg). The extract (400 mg/kg) caused a significant (p<0.05) reduction in the number of recruited leucocytes and it''s inhibition of peritoneal exudate formation was comparable to that of indomethacin at a dose of 10 mg/kg. The exudate formation inhibited by 400 mg/kg of the extract in the granuloma air pouch test was comparatively less to that of indomethacin at a dose of 10 mg/kg. The findings of the study indicate that the aqueous extract of Stereospermum kunthianum stem bark possesses antiinflammatory activity which is probably related to the inhibition of prostaglandin synthesis. This is a possible rationale for its folkloric use as an antiinflammatory agent.     

Correlation Between In Vivo Antipyrine Metabolite Formation and Theophylline Metabolism in Rats

Two model substrates for oxidative hepatic enzyme activity, viz. antipyrine (A) and theophylline (T), were given simultaneously to rats by iv administration. Blood concentrations of A and T were measured by a high-performance liquid chromatographic (HPLC) method. Urinary excretions of A, T, and the major metabolites arising from A—4-hydroxyantipyrine (OHA), norantipyrine (NORA), 3-hydroxymethylantipyrine (HMA), and 4,4-dihydroxyantipyrine (DOHA)—and from T—1-methyluric acid (1-MU) and 1,3-dimethyluric acid (1,3-DMU)—were also determined by HPLC. It was found that the pharmacokinetic parameters obtained after the simultaneous administration of A and T at relatively low dose levels (A, 5.0 mg; and T, 1.3 mg) were not different from those obtained after the separate administration of A or T at the same dose level. In order to investigate whether the metabolic pathways of A and T are mediated by the same or closely related forms of the cytochrome P-450 system, metabolic clearances of A (CL_A,M) and T (CL_T,M) and the clearances for production of their various metabolites, obtained in untreated rats and in rats pretreated with 3-methylcholanthrene (MC) or with MC followed by 9-hydroxyellipticine (E), were correlated. These two compounds are a selective cytochrome P-448 inducer and inhibitor, respectively. Strong correlations were found between CL_T,M and the clearances for production of OHA, NORA, and DOHA but not HMA. The best correlation, however, was observed between CL_T,M and CL_OHA, not only when all data points were taken into account (r = 0.99), but also in separate pretreatment groups (r ranging from 0.87 to 0.92). Moreover, the slopes of these correlation lines varied only slightly among groups, while the intercepts were not significantly different from zero. In the separate pretreatment groups, the correlation coefficients for the correlations between CL_T,M and the clearance for production of the other metabolites of A were considerably lower, while the slopes of the correlation lines varied substantially. Clearances for production of the metabolites of T were strongly correlated with each other (r = 0.99) and with CL_OHA (r = 0.95). It can be concluded that theophylline metabolism and formation of OHA are mediated by the same or very similar forms of cytochrome P-450, whereas formation of the other major metabolites of A is not or only partly. The study of the various pathways of metabolism after simultaneous administration of drugs is a powerful tool in the study of correlations in drug metabolism in vivo.     

鸡尾酒法评价石蒜对大鼠细胞色素P450酶活性的影响

目的 运用鸡尾酒法评价石蒜对细胞色素P450酶活性的影响.方法 将大鼠随机分为对照组和石蒜低、高剂量组.对照组给予生理盐水,石蒜低、高剂量组大鼠灌胃给药0.5,1.0 g·kg-1石蒜,连续给药15d.然后第16天给予探针药物,UPLC-MS/MS检测探针药浓度.结果 与对照组对比,石蒜低剂量组和高剂量组的安非他酮AU...     

中药协同抗真菌药物抗念珠菌的研究进展

侵袭性念珠菌感染已成为备受关注的公共卫生问题,而现行治疗念珠菌感染的药物有限,联合用药是一种实用有效的新药开发策略。从天然植物（尤其是药用植物）中提取的化合物及其衍生物与传统的抗真菌剂联合使用对杀灭念珠菌具有显著的协同作用。归纳了念珠菌对传统抗真菌药物的耐药情况,并总结了中药协同传统抗真菌药物的抑菌活性和抑菌机制,以期为抗念珠菌新型治疗策略的研究提供参考依据。     

UPLC-MS/MS法测定茯苓、茯苓皮和茯神中茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸

目的 建立超高效液相色谱串联质谱（UPLC-MS/MS）法同时测定茯苓、茯苓皮和茯神中茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸。方法 采用Shim-pack GIST C₁₈ AQ色谱柱（100 mm×2.1 mm,3 μm）,以乙腈–0.1%甲酸为流动相,梯度洗脱,体积流量0.4 mL/min,柱温40 ℃,进样量5 μL。质谱采用离子源：ESI,负离子模式采集,采集模式：多反应监测（MRM）,离子源温度150 ℃,毛细管电压2.5 kV,锥孔电压40 V,去溶剂气流量900 L/h,去溶剂气温度500 ℃。结果 茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸在各自的线性范围内线性关系良好,平均回收率分别为97.80%、99.65%、97.32%、102.82%、99.57%,RSD值分别为3.46%、1.29%、3.01%、3.11%、1.89%。茯苓皮中5种三萜类成分含量均高于茯苓和茯神。结论 本法具有分析速度快、准确度高的优点,可为茯苓、茯苓皮和茯神的质量标准提高和开发利用提供依据。     

Correlation of Partitioning of Nitroimidazoles in the n-Octanol/Saline and Liposome Systems with Pharmacokinetic Parameters and Quantitative Structure–Activity Relationships (QSAR)

The partitioning of a series of nine nitroimidazole drugs in liposomes (log K _m) of various compositions has been determined and compared to their partitioning in the n-octanol/saline system (log K) at 30°C. The log K _m ranged from 1.5 to 0.5 and was three- to fourfold greater than the log K; further, the linear correlation coefficient was greatest when cholesterol (CHOL)-free liposomes were used. Functional-group contributions were compared from their hydrophobic substituent constants and, except in the case of RO-07-2044 and iodoazomycin riboside, yielded negative values in all systems. Literature values of four pharmacokinetic parameters obtained in dogs and acute LD₅₀ values of the nitroimidazoles in BALB/c mice were highly correlated with log K or log K _m only in CHOL-free liposomes. Comparing the relative sensitizing effect of the nitroimidazoles in murine EMT-6 or Chinese hamster V79 tumor cell cultures and their partition coefficients, the correlation in EMT-6 cells was poor, whereas the correlation in V79 cells was >0.9 when log K _m was used but <0.6 when log K was used. Thus, the liposome model is a better predictor of nitroimidazole activity than the n-octanol/saline system and, also, it is a more flexible model for selecting the optimum conditions for QSAR studies.     

Anti-inflammatory effect of leaves of Eriobotrya japonica correlating with attenuation of p38 MAPK, ERK, and NF-κB activation in mast cells

Mast cell-mediated allergic inflammation is involved in many diseases such as asthma and sinusitis. Mast cells induce synthesis and production of pro-inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 with immune regulatory properties. In the present study, we investigate the effect an unspecified aqueous extract from leaves of Eriobotrya japonica Lindl. (Rosaceae) (LEJL) on the expression of pro-inflammatory cytokines and its possible mechanisms of action in human mast cells (HMC-1). LEJL dose-dependently inhibited phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 (PMACI)-induced gene expression and secretion of TNF-α, IL-6, and IL-8. LEJL attenuated PMACI-induced activation of nuclear factor (NF)-κB, and specifically blocked activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) but not that of c-jun N-terminal kinase. The inhibitory effect of LEJL on the pro-inflammatory cytokines was likely NF-κB, p38 MAPK, and ERK dependent. Our in vitro studies provide evidence that LEJL might contribute to the treatment of mast cell-derived allergic inflammatory diseases.     

The pharmacology of VA21B7: an atypical 5-HT3 receptor antagonist with anxiolytic-like properties in animal models

VA21B7 (3-[2-(4-piperonylpiperazinyl) indolyl] carboxaldehyde) was synthesized as a potential 5-HT₃ receptor antagonist. Even though VA21B7 showed a higher affinity towards 5-HT₃ receptors as compared to other receptors studied, it was not a potent 5-HT₃ receptor antagonist either in the periphery or in the brain. In a simple animal model of anxiety such as the two-compartment box in mice, a remarkable anxiolytic-like effect was found at doses of 2–500 µg/kg IP and also at low oral doses, in the microgram range. These drug doses did not produce any significant effect on spontaneous motor activity of mice. The anxiolytic profile of VA21B7 was further explored using other models of anxiety in rats such as the elevated plus-maze and punished-drinking. VA21B7 was compared with standard 5-HT₃ receptor antagonists such as ondansetron, tropisetron and granisetron, with the 5-HT_1A agent buspirone and with diazepam. In the plus-maze, VA21B7 showed an anxiolytic-like profile after doses of 0.25–0.5 mg/kg IP or 2–4 mg/kg PO which did not modify the number of total entries into the open and closed arms of the maze. Diazepam, granisetron and tropisetron were also effective in this test but not ondansetron and buspirone. VA21B7 was also able to release suppressed behaviour in the punished-drinking test. The dose-response curve was bell-shaped with a peak at 2–4 mg/kg. At variance with other studies, 5-HT₃ receptor antagonists also increased the number of shocks taken in this test and the dose-response curve was also bell-shaped. VA21B7 was not anticonvulsant like diazepam, its anxiolytic action in the light/dark test was not flumazenil-sensitive and there was no rebound anxiogenic effect on withdrawal from chronic VA21B7 treatment for 15 consecutive days. Moreover, VA21B7 was not amnesic like the benzodiazepines but low doses of 2–4 mg/kg reduced the memory deficits induced in rats by scopolamine. Much higher doses were necessary to decrease spontaneous motor activity in rats. Since VA21B7 appears to be well tolerated in rodents at high doses, we think that it is of potential interest as an anxiolytic in humans.