从天然植物制取(一)棉酚

本文首次报道从天然植物——海岛棉籽中分离出(-)棉酚。同时发现了受试的各种棉籽所含棉酚的光学活性的规律。(1)棉籽中棉酚的两个对映体(-)棉酚和(+)棉酚一般是不等量的,故其成分应为(±)棉酚和过量的(-)棉酚或(+)棉酚;(2)同种属棉籽含有相同旋光性的过量对映体,如海岛棉籽均含有过量的(-)棉酚,多数品种所含棉酚的光学纯度为10～25%,陆地棉籽则均含有过量的(+)棉酚,其相应棉酚的光学纯度为10～20%。     

消旋棉酚晶态结构的研究

目的:研究消旋棉酚晶形结构。方法:采用红外光谱(IR)、差示扫描量热法(DSC)、测定溶解度和粉末X射线衍射法(XRD)来研究消旋棉酚晶态结构。结果:消旋棉酚[(±)G]、左旋棉酚[(-)G]和右旋棉酚[(+)G]的红外谱图基本相同;DSC图谱及热特征数据不一致;在消旋棉酚的饱和溶液中加入光学活性棉酚,光学活性棉酚可以继续溶解,并且有旋光产生;(±)G与(-)G及(+)G的XRD图完全不同。结论:消旋棉酚晶体属于外消旋化合物。     

(-)和(+)棉酚对雄大鼠生育力的影响

棉酚有明显的抗雄性生育作用,但在理论上尚不清楚消旋棉酚的抗生育作用和毒性来自那一种光学异构体。已有报告指出(+)棉酚无毒无效。但对(-)棉酚的研究迄今尚未有报道。本文应用本所合成室制备之(+)和(-)棉酚,观察了他们的抗生育作用。实验用Wistar雄大鼠(190～220g)25只,分为对照,(+)棉酚30mg/kg,(-)棉酚15和30 mg/kg以及消旋棉酚30 mg/kg等5组。每天喂药1次,(+)棉酚和(-)棉酚     

二苯乙烯类化合物对蛋白激酶C的抑制作用

报道15种二苯乙烯类化合物对蛋白激酶C(PKC)活性的影响。其中从中药金雀根中分得的3种二苯乙烯类低聚体α-viniferin,kobophenol A 和 miyabenolC,它们抑制PKC的IC₅₀分别为62.5,52.0和27.5μmol·L^-1。另外6种含酚羟基的二苯乙烯化合物对PKC也显示不同程度的抑制作用,但当酚羟基全甲基化或全乙酰化后其抑制作用大大降低甚至消失。酶动力学研究证明miyabenolC对PKC的抑制作用属于非竞争性抑制。     

氚标记(+)与(-)棉酚在大鼠主要脏器的亚细胞分布及共价结合

给大鼠腹腔及睾内注射氚标记的(+)与(-)棉酚后第7、18天,对主要脏器中各亚细胞组分的总放射活性及共价结合的放射活性进行了动态观察。结果表明,(-)棉酚在心肌线粒体共价结合放射活性较明显高于(+)棉酚;(+)及(-)棉酚在睾丸细胞膜、微粒体共价结合的放射活性随时间增高,且(-)棉酚较为明显。     

灵芝多糖对小鼠T细胞蛋白激酶A和蛋激酶C活性的影响

:目的 :观察灵芝多糖体外对小鼠T细胞蛋白激酶A (PKA)和蛋白激酶C(PKC)活性是否有影响。方法 :采用反相离子对高效液相色谱法测定PKA和PKC活力。结果 :灵芝多糖GLB7 能引起T细胞中PKA和PKC活性明显增强并具有剂量依赖性 ,达峰时间分别为5min和20min ,于20min及1h分别恢复到基础水平 ;GLB7 还可引起T细胞中PKC发生质膜转位 ,并拮抗Stau rosporine对T细胞中PKC的抑制作用。结果 :灵芝多糖的免疫增强和抗肿瘤作用与其增强PKA和PKC活性有关     

棉酚对大鼠胆汁谷胱甘肽含量的影响

<正> de Peyster等证明棉酚与大鼠肝微粒体及人精子体外温育能产生自由基,推测可能是棉酚生物活性的基础。新近报道右旋(+)及左旋(-)棉酚(gossypol,G)体外与大鼠肝及肾微粒体温育能产生自由基。但自由基的生成是否为棉酚抗生育以及血清谷丙转氨酶(ALT)升高的毒性机理,值得进一步探讨。     

棉酚及醋酸棉酚的HPLC分析

棉酚(Gossypol)近年用作男用避孕药,由于其毒性,规定人与家畜用量的上限浓度为0.045%。棉酚性质不稳定,一般与醋酸棉酚配成1∶1浓度混合使用。曾报道棉酚在人及雄性哺乳类动物试验体内的抗生育力及体外的杀精子活力,但精确的药理实验必须提供纯度高的供试品。棉酚的分析方法有与芳香胺形成复合物     

消旋棉酚拆分的研究——Ⅱ.手性α-甲基苯乙胺及α-甲基苄胺为拆分剂

本文报道用中压柱色谱快速分离S或R-α-甲基苯乙胺及S或R-α-甲基苄胺缩(±)-棉酚的方法,可得光学活性胺缩(+)或(一)-棉酚非对映体,经水解分别得到(+)或(一)-棉酚。并证明胺缩光学活性棉酚非对映体之间有互相转化的性质,此特性可利用于棉酚对映体的转化。     

ATP敏感性钾电流与蛋白激酶关系的研究

目的观察蛋白激酶A(PKA)及蛋白激酶C(PKC)抑制剂和蛋白脱磷酸化物质对大鼠心室肌细胞ATP敏感性钾电流 (IKATP)的影响 ,探讨克罗卡林 (cromakalim)开放ATP敏感性钾通道的作用机制。方法采用全细胞膜片钳技术记录心室肌细胞IKATP。结果在37℃时克罗卡林 (1μmol·L-1)可阻断ATP的抑制作用 ,诱导出IKATP。PKA抑制剂PKI(6～22)amide (1μmol·L -1),可模拟克罗卡林的作用 ,激活IKATP;而PKC抑制剂calphosticC无此作用。同时还观察到蛋白脱磷酸化物质butanedioemonoxime(BDM,5mmol·L -1)也可诱发出IKATP。结论克罗卡林开放IKATP 机制与抑制PKA的活性有关 ,而与PKC无关。     

SIGNAL TRANSDUCTION BY PROTEIN KINASE C IN MAMMALIAN CELLS

1. The past two decades have witnessed great advances in our understanding of the role of protein kinase C (PKC) in signal transduction. The Ca²⁺-activated, phospholipid-dependent protein kinase discovered by Nishizuka's group in 1977 is now a family of at least 11 isoforms. Protein kinase C isoforms exist in different proportions in a host of mammalian cells and each isoform has a characteristic subcellular distribution in each cell type. 2. Stimulation of a specific PKC is oform often causes redistribution of the isoform from one subcellular compartment to another compartment where it complexes with and phosphorylates a specific protein substrate. 3. The interaction of a specific PKC isoform with its protein substrate may directly activate a specific function of the cell or may trigger a cascade of protein kinases that ultimately stimulates a specific response in differentiated cells or regulates growth and proliferation in undifferentiated cells.     

人参二醇组皂甙对佛波酯诱导心肌细胞蛋白激酶C活力的影响

人参二醇组皂甙对佛波酯诱导心肌细胞蛋白激酶Ｃ活力的影响徐学萍，肖殿模，周文华，王小鲁，张俊宝，邵春杰，赵雪俭，陈华粹（中国医学科学院，中国协和医科大学基础医学研究所北京１００００５）人参皂甙为人参主要活性成分之一，有多种药理活性和防治心血管疾病的作用...     

Effect of 8-bromo-cAMP on the tetrodotoxin-resistant sodium (Nav 1.8) current in small-diameter nodose ganglion neurons

We examined whether 8-bromo-cAMP (8-Br-cAMP)-induced modification of tetrodotoxin-resistant (TTX-R) sodium current in neonatal rat nodose ganglion neurons is mediated by the activation of protein kinase A (PKA) and/or protein kinase C (PKC). In 8-Br-cAMP applications ranging from 0.001 to 1.0mM, 8-Br-cAMP at 0.1mM showed a maximal increase in the peak TTX-R Na(+) (Nav1.8) current and produced a hyperpolarizing shift in the conductance-voltage (G-V) curve. The PKC inhibitor bisindolylmaleimide Ro-31-8425 (Ro-31-8425, 0.5microM) decreased the peak Nav 1.8 current. The Ro-31-8425-induced modulation of the G(V)(1/2) baseline (a percent change in G at baseline V1/2) was not affected by additional 8-Br-cAMP application (0.1mM). The maximal increase in Nav 1.8 currents was seen at 0.1microM after the application of a PKC activator, phorbol 12-myristate 13-acetate (PMA) and forskolin. The PMA-induced increase in Nav 1.8 currents was not significantly affected by additional 0.1mM 8-Br-cAMP application. Intracellular application of a PKA inhibitor, protein kinase inhibitor (PKI, 0.01mM), inhibited the baseline Nav 1.8 current, significantly attenuated the 8-Br-cAMP-and PMA-induced increase in the peak Nav 1.8 current, and caused a significant increase in the slope factor of the inactivation curve. The PKI application at a higher concentration (0.5mM) greatly inhibited the PMA (0.1microM)-induced increase in the peak Nav 1.8 current amplitude and further enhanced the Ro-31-8425-induced decrease in the current. These results suggest that the 8-Br-cAMP-induced increase in Nav 1.8 currents may be mediated by activation of both PKA and PKC.     

PKC and PKA inhibitors reinstate morphine-induced behaviors in morphine tolerant mice

Male Swiss Webster mice exhibited antinociception, hypothermia and Straub tail 3h following a 75mg morphine pellet implantation. These signs disappeared by 72h, and the morphine-pelleted mice were indistinguishable from placebo-pelleted ones, although brain morphine concentrations ranged from 200 to 400ng/gm. We previously demonstrated that chemical inhibitors of protein kinase C (PKC) and A (PKA) are able to reverse morphine tolerance in acutely morphine-challenged mice. However, it was not known whether the reversal of tolerance was due to the interaction of kinase inhibitors with the morphine released from the pellet, the acutely injected morphine to challenge tolerant mice, or both. The present study aimed at determining the interaction between the PKC and PKA inhibitors and the morphine released "solely" from the pellet to reinstate the morphine-induced behavioral and physiological effects, 72h after implantation of morphine pellets. Placebo or 75mg morphine pellets were surgically implanted, and testing was conducted 72h later. Our results showed that the intracerebroventricular (i.c.v.) administration of the PKC inhibitors, bisindolylmaleimide I and G?-6976 as well as the PKA inhibitors, 4-cyano-3-methylisoquinoline and KT-5720, restored the morphine-induced behaviors of antinociception, Straub tail and hypothermia in morphine-pelleted mice to the same extent observed 3h following the pellet implantation. The tail withdrawal and the hot plate reaction time expressed as percent maximum possible effect (%MPE) was increased to 80-100 and 41-90%, respectively, in PKC and PKA inhibitor-treated morphine tolerant mice compared to 2-10% in non-treated mice. Similarly, a significant hypothermia (1.3-4.0 degrees C decrease in body temperature) was detected in PKC and PKA inhibitor-treated morphine tolerant mice compared to an euthermic state in non-treated morphine tolerant mice. Finally, the Straub tail score was increased to 1.1-1.6 in PKC and PKA inhibitor-treated tolerant mice, whereas it was totally absent in non-treated animals. It is noticeably that the kinase inhibitors used in the study had no effect in placebo-pelleted mice. Our results provide the first evidence on the ability of PKC and PKA inhibitors to reinstate the behavioral and physiological effects of morphine in non-challenged morphine-tolerant animals.     

肿瘤坏死因子对牛肺动脉内皮细胞的损伤及蛋白激酶C抑制剂的抑制作用

研究表明:肿瘤坏死因子(TNF)可剂量依赖地引起牛肺动脉内皮细胞乳酸脱氢酶释放率(LDH%)升高,促进中性粒细胞向内皮细胞粘附,并可抑制内皮细胞增殖和DNA合成。蛋白激酶C(PKC)抑制剂1-(5-异喹啉磺酰基)-2-甲基哌嗪(H-7)和槲皮素一方面可剂量依赖地抑制TNF对内皮细胞的直接损伤,另方面又可通过抑制TNF诱导的中性粒细胞对内皮细胞粘附增加,减轻TNF对内皮细胞的间接损伤作用,同时还可抑制TNF对内皮细胞增殖和DNA合成的影响,从而间接加强内皮细胞对损伤的自我修复。     

吩噻嗪类化合物抑制肿瘤细胞多药耐药及蛋白激酶C活性的三维构效关系研究

目的：利用本室诱导建立的耐药细胞株K562/A02,研究在体外条件下吩噻嗪类衍生物(PTZs)逆转多药耐药(MDR)活性的构效关系。方法与结果：利用已知PKC Cys 2功能区晶体结构,结合计算化学和分子图形学手段对PKC抑制剂与PKC蛋白分子间可能的相互作用模式进行探讨。结果表明,2位取代各种基团逆转MDR作用强度依次为：COC₃H₇>CF₃>COCH₃>H。边链哌嗪环4′-位取代基作用强度为:CH₃>COOC₂H₅>C₂H₄OH。结论：选出代表性化合物测定对鼠脑的抑制活性,初步三维构效关系研究表明,PTZs抑制PKC活性确实与特定的立体结构特征有关。本研究为进一步探索PTZs,PKC和MDR三者间的内在机制和设计有效PKC抑制剂或多药耐药逆转剂提供了新的途径。     

PROTEIN KINASE C AND TRANSMITTER RELEASE

1. Protein kinase C (PKC) is an important second messenger-activated enzyme. In noradrenergic nerves it appears to be tonically activated by diacylglycerol (DAG) to facilitate transmitter release and the steps in this involve activation of phospholipase C, generation of DAG and activation of PKC. It is suggested that the subsequent facilitation of transmitter release is due to the phosphorylation of proteins involved in the release process distal to Ca²⁺entry, presumably those involved in vesicle dynamics. 2. There are differences between central noradrenergic neurons and sympathetic nerves. In central neurons PKC appears to be tonically active and its inhibition results in a decrease in noradrenaline release under most, if not all, conditions. 3. In sympathetic nerves PKC inhibitors only decrease transmitter release during high-frequency stimulation and not during low-frequency stimulation. At high frequency there is a gradual increase in the effect of PKC inhibitors on transmitter release during the first 15 s of a stimulation train. It is suggested that this is due to a progressive rise in intracellular Ca²⁺ and a consequent activation of PKC. 4. Activation of PKC by phorbol esters produces a large enhancement in action potential-evoked noradrenaline release in both the central nervous system and in peripheral tissues. The structural requirements of the phorbol esters for maximal effect suggest that the phorbol esters must access the interior of the nerve terminal to activate PKC and the neural membrane acts as a barrier for highly lipophilic phorbol esters, thereby reducing their activity. Activation of PKC represents one of the most powerful ways to enhance transmitter release and may have therapeutic potential.     

伏隔核壳区内注射蛋白激酶A对大鼠吗啡条件性位置偏爱的作用

目的:观察伏隔核环磷酸腺苷-蛋白激酶A通路在吗啡犒赏相关学习中的作用。方法:选用SD大鼠伏隔核壳区内注射吗啡所致的条件性位置偏爱模型,用蛋白激酶A的拮抗剂Rp-cAMPS干预,测评大鼠在伴药侧停留时间的变化。结果:蛋白激酶A抑制剂没有阻断吗啡所致的条件性位置偏爱(P<0.01)。结论:伏隔核环磷酸腺苷-蛋白激酶A通路在吗啡犒赏相关学习中作用相对较小。     

Analysis of phosphorylation-dependent modulation of Kv1.1 potassium channels

The voltage-gated potassium channel Kv1.1 contains phosphorylation sites for protein kinase A (PKA) and protein kinase C (PKC). To study Kv1.1 protein expression and cellular distribution in regard to its level of phosphorylation, the effects of PKA and PKC activation on Kv1.1 were investigated in HEK 293 cells stably transfected with Kv1.1 (HEK 293/1). Without kinase activation, HEK 293/1 cells carry unphosphorylated Kv1.1 protein in the plasma membranes, whereas large amounts of phosphorylated and unphosphorylated Kv1.1 protein were located intracellularly. Activation of PKA resulted in phosphorylation of intracellular Kv1.1 protein, followed by a rapid translocation of Kv1.1 into the plasma membrane. Patch-clamp analysis revealed an increase in current amplitude upon PKA activation and demonstrated differences in the voltage dependence of current activation between unphosphorylated and phosphorylated Kv1.1 channels. In contrast to PKA, even prolonged activation of PKC did not lead to direct phosphorylation of Kv1.1, but induced Kv1.1 protein synthesis. Thus, protein kinases have direct and indirect effects on the functional expression of voltage-gated potassium channels. Our data suggest that the synergistic action of protein kinases may play an important role in the fine-tuning of Kv channel function.