Sexual dimorphism in rats with respect to locomotor activity and circling behavior

Male and female rats were tested for locomotor activity and spontaneous circling (rotation) at 4, 6, 8, 11, 13 and 15 weeks of age. Locomotor activity of females increased with age, and significant intersex differences which became apparent by 8 weeks of age were attributed to the greater persevering tendency of the females. Spontaneous rotation, on the other hand, did not change with age and significant intersex differences were not evident. Moreover, locomotor activity and rotation were not correlated at any age. In contrast to spontaneous rotation, amphetamine induced significantly more rotation in older (18 week) than in younger (5 week) females and males of both ages. Apomorphine, on the other hand, also elicited more rotation in older than in younger females, but not in males. In addition, intersex differences were not evident in younger animals tested with either drug. These data suggested that the greater persevering tendency and lateralization of females compared to males may be related to bilateral functional imbalances in nigrostriatal activity.     

Structure-activity relationship study of androstene steroids with respect to local anti-inflammatory activity

A sex hormone, 3beta-acetoxy-17beta-hydroxy-androst-5-ene (1) (CAS 1639-43-6), was isolated from aerial parts of Acacia nilotica. This compound is reported to have anti-inflammatory activity. In view of this, considering this molecule as a lead molecule different androstene compounds were synthesized to study their potency and structure-activity relationship with respect to local anti-inflammatory activity. The experiments indicated that 17 ketonic compounds were more active towards inflammation than their oxime analogues. Similarly, for the compounds containing an acetyl group fixed at C-3 position a decreasing trend of activity was observed in the order of ketonic, hydroxyl, oxime and acetyl group, respectively, when these groups are at C-17 position.     

Peptides as receptor ligand drugs and their relationship to G-coupled signal transduction

Peptides act as effector agents that regulate and/or mediate physiological processes, serving as hormones, neurotransmitters and signal transducing factors. The low molecular weight peptides affect receptor-mediated events, which influence cardiovascular, gastrointestinal and neurocranial systems. While some peptides have been marketed as drugs, many have served as leads or templates for the development of non-peptide drugs that mimic peptide actions. This review presents the advantages and disadvantages of using peptides as drugs that bind as ligands to cell-surface receptors and considers their applications in such events. The value of both the peptides and their mimics is based on their participation in the biomodulation of physiological processes, which frequently employ scaffolding proteins acting in a cascading sequence of protein-to-protein interactions. The peptides bind to G-coupled surface receptors to initiate a signal that is transduced to the interior of the cell through multiple layers of phosphorylating enzymes and binding proteins. Peptides have been further employed to identify the molecular targets of signal transduction, the uncoupling of which might provide a means for various disease therapies. The exploitation of such peptide-mediated signal pathways, which are of primary importance to tumour cells, may provide an attractive strategy for anticancer therapy in the future.     

Comparison of aminoglycoside antibiotics with respect to uptake and lethal activity in Escherichia coli

Forty-five aminoglycoside antibiotics and related compounds were compared for their ability to induce the accumulation of dihydrostreptomycin in Escherichia coli K12. The common aminoglycosides and a streptothricin antibiotic all induced enhanced uptake within a relatively narrow concentration range. These concentrations were lethal to the bacteria. Comparison of aminoacyl derivatives of tobramycin and apramycin, the latter synthesized utilizing transition-metal cations to selectively control the site of substitution, revealed that 1-N-aminoacyl modifications resulted in an increased ability to induce enhanced uptake. 2'-N-Aminoacyl modifications were also effective at inducing enhanced uptake, albeit without noticeable improvement over parent. The findings from this structure-activity comparison support the proposition that aminoglycosides share a common critical target (most likely the ribosome), which, when acted upon, results in both drug accumulation and killing.     

ADP-induced platelet aggregation and inhibition of adenylyl cyclase activity stimulated by prostaglandins: signal transduction mechanisms

ADP is the oldest and one of the most important agonists of platelet activation. ADP induces platelet shape change, exposure of fibrinogen binding sites, aggregation, and influx and intracellular mobilization of Ca2+. ADP-induced platelet aggregation is important for maintaining normal hemostasis, but aberrant platelet aggregation manifests itself pathophysiologically in myocardial ischemia, stroke, and atherosclerosis. Another important aspect of ADP-induced platelet activation is the ability of ADP to antagonize adenylyl cyclase activated by prostaglandins. ADP-induced inhibition of the stimulated adenylyl cyclase activity does not appear to play a role in ADP-induced platelet aggregation in vitro or in vivo. It is believed that a single ADP receptor mediates the above two ADP-induced platelet responses in platelets. The ADP receptor mediating ADP-induced platelet aggregation and inhibition of the stimulated adenylyl cyclase activity has not been purified. Therefore, the nature of molecular mechanisms underlying the two seemingly unrelated ADP-induced platelet responses remains either unclear or less well understood. The purpose of this commentary is to examine and make suggestions concerning the role of phospholipases and G-proteins in the molecular mechanisms of signal transduction underlying the two ADP-induced platelet responses. It is hoped that such discussion would stimulate thinking and invite future debates on this subject, and energize investigators in their efforts to advance our knowledge of the details of the molecular mechanisms of ADP-induced platelet activation.     

Interferon signal transduction of biphenyl dimethyl dicarboxylate/amantadine and anti-HBV activity in HepG2 2.2.15

Biphenyl dimethyl dicarboxylate (DDB) is a hepatoprotectant, which is used as an adjuvant agent in a treatment for chronic hepatitis. Amantadine is an antiviral agent, which is utilized primarily in the treatment of influenza, but also, occasionally in the treatment of hepatitis C. In a previous study, we reported that DDB, coupled with amantadine, would exert an anti-HBV effect, via the induction of interferon-inducible gene expression in the HepG2 2.2.15 cell line. The primary objective of the present study was to determine whether or not DDB and/or amantadine exhibit anti-HBV properties, and what mechanisms of action might be involved in such properties. In our study, we were able to determine that DDB stimulates Jak/Stat signaling, and induces the expression of interferon alpha (IFN-alpha) stimulated genes, most notably 6-16 and ISG12. In addition, the antiviral effectors induced by IFN-alpha, PKR, OAS, and MxA, were regulated in the presence of DDB at its optimal concentration (250 microg/mL), to a degree commensurate with the degree of induction associated with the IFN-alpha treated group. Finally, we determined that the replication of pregenomic RNA and HBeAg was inhibited by DDB treatment, and this inhibition was maximized when coupled with the administration of amantadine (25 microg/mL). In conclusion, the results of this study demonstrated clearly that DDB, as well as the combination of DDB/amantadine, directly inhibited IFN-alpha signaling-mediated replication of HBV in infected hepatocytes, and thus may represent a novel treatment for chronic hepatitis B, which would be characterized principally by its improved safety over other treatment strategies.     

Ethanol and caffeine: A complex interaction with respect to locomotor activity and central catecholamines

The effect of ethanol and caffeine on the locomotor activity (motility) of mice was investigated. Caffeine, 25 mg/kg, which by itself stimulated motility increased the stimulation of motility elicited by 1–2g/kg ethanol. When 3 g/kg ethanol was given, caffeine, 25 and 50 mg/kg, did not change the level of activity while 100 mg/kg abolished the increase in activity caused by ethanol alone. A mixture of ET495 and clonidine, which stimulate central dopamine and noradrenaline receptors respectively, causes reversal of the reserpine-induced suppression of motility. Caffeine, 25 mg/kg, but not ethanol, 1 g/kg, potentiated this reversal. The rate of synthesis of brain catecholamines was estimated using two different methods, i.e. the accumulation of Dopa following inhibition of its decarboxylation by NSD1015 and the accumulation of ³H-dopamine and ³H-noradrenaline after injection of ³H-tyrosine. Both methods indicated a marked increased synthesis of brain catecholamines after combined treatment with caffeine and ethanol as compared with the result obtained after either drug alone or after saline injections. It is suggested that central catecholamine mechanisms are involved in the interaction between ethanol and caffeine.     

TAL对慢支模型大鼠肺泡巨噬细胞凋亡的影响及部分机制研究

目的探讨枇杷叶三萜酸(TAL)对慢支模型(CB)大鼠肺泡巨噬细胞(AM)活性及凋亡的影响及其可能的作用机制。方法应用BCG联用LPS的方法复制大鼠CB模型,采用体内外给药的方法,观察TAL及MAPK3条通路对CB大鼠AM凋亡及活性的影响。MTT法检测细胞活性,电镜观察AM凋亡,流式细胞技术检测AM凋亡率及AM中凋亡相关基因Bcl-2、Bax的表达。Western blot法检测AM中ERK蛋白磷酸化水平。结果①与正常对照组比较,模型大鼠支气管肺泡灌洗液中AM数增加(P<0.01),而TAL灌胃给药可抑制模型大鼠异常增多的AM数量(P<0.01)。②慢支模型组AM活性较正常组相比明显增强(P<0.01),TAL可抑制CB模型组大鼠AM的活性(P<0.05)。③与正常组比较,模型大鼠AM凋亡率明显降低(P<0.01);TAL给药组及ERK通路抑制剂PD98059组AM凋亡率较模型组比较升高(P<0.05,P<0.01)。而JNK通路抑制剂Curcumin组AM凋亡率降低(P<0.05)。④模型大鼠AMERK磷酸化水平明显升高(P<0.01);TAL(5mg.L-1)体外给药可抑制慢支大鼠AM内ERKMAPK通路的磷酸化(P<0.05)。⑤模型大鼠AMBax表达明显降低而Bcl-2表达升高(P<0.01),TAL给药组可降低慢支大鼠AMBcl-2表达,升高Bax表达。结论慢支模型大鼠AM活性增强、凋亡减少,TAL可诱导AM凋亡,抑制AM活性,使AM内Bcl-2/Bax的表达趋于平衡。ERK、JNKMAPK信号传导通路参与慢支大鼠AM凋亡的调节,JNKMAPK信号通路促进AM凋亡而ERKMAPK信号通路抑制AM凋亡。TAL的促AM凋亡作用可能与其抑制慢支大鼠AMERKMAPK信号通路的磷酸化活化、调节Bcl-2/Bax的表达有关。     

Developing inhibitors to selectively target two-component and phosphorelay signal transduction systems of pathogenic microorganisms

Two-component signal transduction systems and their expanded variants known as phosphorelays are integral elements of the virulence and antimicrobial resistance responses of a wide range of pathogenic bacteria and fungi and also regulate essential functions. As a consequence, two-component systems and phosphorelays are recognized targets for the development of novel antimicrobial agents and a number of chemically synthesized inhibitors from different chemical classes have been identified by compound library screens. However, in the majority of cases these compounds do not appear to be selective for signal transduction pathways and exert their effect by multiple mechanisms of action. The key to designing molecules to selectively disrupt signal transduction may lie with the conserved features of response regulators and the structural analysis of complexes of signaling proteins.     

Synthesis of taxoids with improved cytotoxicity and solubility for use in tumor-specific delivery

To develop effective taxane-antibody immunoconjugates, we have prepared a series of modified taxanes that have both improved toxicity and solubility in aqueous systems as compared to paclitaxel (1a). These taxanes have been modified at either the C-10 or C-7 position and were found to be very cytotoxic against both normal and multi-drug-resistant (MDR) cells, as well as up to 30 times more soluble than paclitaxel in various buffer systems.     

Coumarin derivatives with tumor-specific cytotoxicity and multidrug resistance reversal activity

A preliminary exploration of coumarin derivatives as novel multidrug resistance (MDR) modulators was carried out to determine the basic features of the structure responsible for the MDR reversal activity. Among 44 coumarins, 14 compounds moderately induced the reversal of MDR (fluorescence activity ratio (FAR) values > 1). The most active compound, 6-hydroxy-3-(2-hydroxyethyl)-4-methyl- 7-methoxycoumarin [C34], was equally potent as a MDR modulator verapamil. These data show a relationship between the chemical structure and MDR-reversal effect on tumor cells. All coumarins tested were more cytotoxic against tumor cells than normal cells. Several compounds displayed potent cytotoxic activities (CC50 15 - 29 microg/mL in HSC cells), comparable with that of gallic acid (CC50 = 24 microg/mL). Both 6-hydroxy- 7-methoxy-4-methyl-3-isopropylcoumarin [C43] and 3-ethyl-6-hydroxy- 7-methoxy-4-methylcoumarin [C44] showed the highest tumor-specific cytotoxicity (SI value = 4.1 and 3.6, respectively). We conclude that coumarins are potentially potent new MDR modulators with low toxicity against normal cells. A deeper understanding of the relationship between their structures and their potency will contribute to the design of optimal agents.     

Biological evaluation and molecular docking studies of nitro benzamide derivatives with respect to in vitro anti-inflammatory activity

A series of nitro substituted benzamide derivatives were synthesized and evaluated for their potential anti-inflammatory activities in vitro. Firstly, all compounds (1–6) were screened for their inhibitory capacity on LPS induced nitric oxide (NO) production in RAW264.7 macrophages. Compounds 5 and 6 demonstrated significantly high inhibition capacities in a dose-dependent manner with IC₅₀ values of 3.7 and 5.3 μM, respectively. These two compounds were also accompanied by no cytotoxicity at the studied concentrations (max 50 μM) in macrophages. Molecular docking analysis on iNOS revealed that compounds 5 and 6 bind to the enzyme more efficiently compared to other compounds due to having optimum number of nitro groups, orientations and polarizabilities. In addition, 5 and 6 demonstrated distinct regulatory mechanisms for the expression of the iNOS enzyme at the mRNA and protein levels. Specifically, both suppressed expressions of COX-2, IL-1β and TNF-α significantly, at 10 and 20 μM. However, only compound 6 significantly and considerably decreased LPS-induced secretion of IL-1β and TNF-α. These results suggest that compound 6 may be a multi-potent promising lead compound for further optimization in structure and as well as for in vivo validation studies.     

A signal transduction pharmacodynamic model of the kinetics of the parasympathomimetic activity of low-dose scopolamine and atropine in rats

We used a novel pharmacokinetic-pharmacodynamic (PK-PD) approach that had been applied for signal transduction kinetics to investigate the kinetics of the parasympathomimetic effect of scopolamine and atropine in rats. The parasympathetic tone was assessed by continuous measurement of the power of the high frequency band (HF) of electrocardiogram (ECG) R-R intervals obtained by power spectral analysis (PSA) of heart rate variability (HRV). To overcome the inherent noise of the HRV-HF data and to quantitatively identify temporal changes in the autonomic tone, a new approach of stepwise regression of the cumulative HF data was applied. The elevation of the parasympathetic tone occurred after a significant lag time (>70 min) following scopolamine administrations [0.25 and 0.5 mg/kg intravenous (iv) bolus or infusion over 100 min], followed by a gradual return to the baseline levels. A similar lag time in parasympathetic stimulation was observed following iv bolus administration of atropine (0.1 mg/kg). The plasma drug concentration versus time data were linked to the response versus time data using a signal transduction pharmacodynamic model that was fitted simultaneously to all four experimental data sets. This PK-PD model resolved the significant discrepancy between the concentration versus time and the response versus time patterns and successfully described the kinetics of the parasympathetic stimulation obtained for different drugs and different rates of administration. This work paves the way for further PK-PD preclinical investigations in this field.     

MAPKs信号转导在类风湿关节炎滑膜细胞中作用及其药物的影响

MAPKs信号转导途径的活化是RA慢性滑膜炎的典型特征,通过这一途径诱导滑膜细胞胞浆蛋白磷酸化,进而使转录因子和核蛋白如cfos、cjun、AP1和NFκB等磷酸化,从而促进细胞增殖和活化。上述机制研究对于RA发病机制的深入了解以及研制开发治疗类风湿关节炎的新型药物具有重要的意义。     

磷酸二酯酶抑制剂与学习记忆相关信号转导通路研究进展

大量的研究表明,环磷酸腺苷反应元件结合蛋白(cAMP response element binding protein,CREB)直接或间接激活相关基因转录,进而表达c-fos、c-jun、BDNF等,在神经元应激损伤后的再生、存活及修复以及学习记忆等方面发挥重要作用。磷酸二酯酶可以水解环磷酸腺苷(cyclic AMP,cAMP)及环磷酸鸟苷(cyclic GMP,cGMP),进而影响其下游信号转导,发挥对CREB的调节作用。该文从磷酸二酯酶抑制剂与学习记忆相关信号通路的关系及在学习记忆障碍中发挥的作用予以综述,并由该通路入手对发现治疗神经退行性变疾病药物作用新靶点的可能性予以展望。