Influence of the ion-balance in the growth medium on the yield and alkaloid content ofDatura stramonium L.

Plants ofDatura stramonium var.tatula L. Torr. were grown for 24 weeks on vermiculite and provided with mineral solutions where the relative proportions of the major anions (N, S, P) and cations (K, Ca, Mg) were varied within a constant total.With all treatments a cyclic transport of alkaloids (hyoscyamine) from the roots to the upper plant parts appeared. The fluctuations in alkaloid content in the leaves followed those in the roots with a delay of 4 weeks.The interionic ratios seemed to influence growth and alkaloid content rather than to affect the ontogenic variations. In general, the response to the different treatments could be divided into two types. The nitrogen treatments which gave at the same time a higher crop yield and an increased hyoscyamine content, and the other treatments where a much lower yield and content was obtained.The scopolamine content on the other hand seemed to be more affected by the developmental stage. Also, the time of maximal yield was not influenced by the ion-balance but rather the climatic conditions.     

灵芝对小鼠空间分辨学习与记忆的影响

本文用Y-型迷宫法测试小鼠空间分辨行为。实验结果表明,每日ig灵芝2.58/kg共7d,有明显促进学习的作用。每日ig灵芝2.5g/kg共7d或ig灵芝5g/kg共7d都能显著地拮坑东莨菪碱所致学习障碍的作用。此外,学习训练后立即ig灵芝2.5g/kg或ig灵芝5g/kg也有明显地改善东莨菪碱损害记忆巩固的作用。     

东莨菪碱镇痛作用的研究

腹腔(25或50mg/kg)或侧脑室注射东莨菪碱(1mg/kg),均使大鼠的痛阈升高42—80%,并持续32—36小时之久。当在恒温室内作昼夜连续观察时,对照组的大鼠在深夜20时至次日8时之前,痛刺激反应稍有增强,此时东莨菪碱组的镇痛作用也相应地减弱,而白天的镇痛作用较强,似有昼夜规律的表现。东莨菪碱的镇痛作用与脑内阿片能系统无关,DA 能暂时增强其镇痛作用,毒扁豆碱能拮抗其镇痛作用,所以,东莨菪碱的镇痛作用,主要是阻滞中枢 M-胆碱能系统的作用所致。     

香水莲花提取物对东莨菪碱诱导记忆障碍小鼠学习记忆能力的影响

探究香水莲花提取物(Nymphaea hybrid extract,NHE)对东莨菪碱诱导记忆障碍小鼠的学习记忆能力的影响。采用腹腔注射东莨菪碱建立记忆障碍模型,Morris水迷宫实验测定小鼠空间学习和记忆能力。水迷宫实验结束后,断头处死小鼠,进行生化指标的测定。结果表明,与模型组小鼠相比,NHE干预后,小鼠的逃避潜伏期明显缩短(P <0. 01),目标象限停留时间百分比和穿越平台次数增加(P <0. 05或P <0. 01),小鼠海马和皮质区的SOD和GSH-PX活力显著升高(P <0. 01或P <0. 05),MDA含量极显著降低(P <0. 01),ACh E活性显著降低(P <0. 01),ACh含量增加(P <0. 01或P <0. 05)。同时,免疫印迹结果表明,NHE能够改善东莨菪碱引起小鼠海马和皮质中ERK、CREB磷酸化水平和BDNF蛋白表达的减少。综上,香水莲花提取物可以提高东莨菪碱诱导的记忆障碍小鼠的学习记忆能力,具体机制涉及缓解大脑的氧化应激损伤,平衡胆碱能系统,激活ERK-CREB-BDNF信号通路。     

No influence of scopolamine hydrobromide on odor detection performance of rats

Despite speculation that the muscarinic cholinergic antagonist, scopolamine, may influence the olfactory sensitivity of rats, there have been no definitive studies on this point to date. In this study, we examined the influence of a range of doses of scopolamine hydrobromine (namely, 0.10, 0.125, 0.15 and 0.20 mg/kg i.p.) on the odor detection performance of 15 adult male Long-Evans rats to ethyl acetate. Air-dilution olfactometry and a go/no-go operant signal detection task were employed. The drug conditions and a saline control were administered to each animal in an order counterbalanced by Latin squares, with 2 day intervals interspersed between tests. Scopolamine had no significant influence on odor detection performance per se, as measured by percent correct S+ and S- responses and a non-parametric signal detection measure of sensitivity. This is in contrast to the relatively large effects previously observed in the same test paradigm for such drugs as the D-1 agonist SKF 38393 and the D-2 agonist quinpirole. These data suggest that scopolamine has no meaningful influence on a well-practiced odor detection task.     

Evolutionary ecology of the tropane alkaloids of Datura stramonium L. (Solanaceae)

Abstract.— Although insect herbivory is frequently assumed to be responsible for the maintenance of plant secondary metabolites such as alkaloids, the assumption is controversial and experimental evidence for this assumption is sparse. We examined natural selection on the two major alkaloids present in the leaves of Datura stramonium and found that both alkaloids came under active selection. We found negative directional selection for scopolamine (natural selection acting to reduce scopolamine levels) and stabilizing selection for hyoscyamine (natural selection acting to maintain an intermediate level of hyoscyamine). We also present evidence that insect herbivores act as the agents of selection on these alkaloids. Finally, we show that there were no trade-offs in resistance to different species of insects.     

Alkaloid production in cultured roots of three species of Duboisia

Cultured roots were obtained from calluses of Duboisia leichhardtii, D. myoporoides and D. hopwoodii. Cultured roots of all these species produced both tropane and pyridine-type alkaloids. The selected cultured roots of D. leichhardtii showed high contents of tropane alkaloids (hyoscyamine 0.53%, scopolamine 1.16%, on a dry weight basis).     

Hippocampal gene expression profiling reveals the possible involvement of Homer1 and GABA(B) receptors in scopolamine-induced amnesia

Scopolamine-treated rats are commonly used as a psychopharmacological model of memory dysfunction and have been extensively studied to establish the effectiveness of acetylcholinesterase inhibitors in the treatment of Alzheimer's disease. Scopolamine is a muscarinic acetylcholine receptor antagonist that induces memory deficits in young subjects similar to those occurring during aging. The amnesic effect of scopolamine is well established but the molecular and cellular mechanisms that sustain its neuropharmacological action are still unclear. The present genome wide study investigates hippocampal gene expression profiling in scopolamine-treated adult rats following stimulation in a spatial memory task. Using microarray and quantitative real-time RT-PCR approaches, we identified several genes previously known to be associated with memory processes (Homer1, GABA(B) receptor, early growth response 1, prodynorphin, VGF nerve growth factor inducible) and multiple novel candidate genes possibly involved in cognition (including calcium/calmodulin-dependent protein kinase kinase 2, dual specificity phosphatase 5 and 6, glycophorin C) that were altered following scopolamine treatment. Moreover, we found that stable over-expression of glutamatergic components Homer1a and 1c in the hippocampus of adult rats induced by recombinant adeno-associated virus vector abolished memory improvement produced by the GABA(B) receptor antagonist SGS742 in scopolamine-treated rats. Taken together, these results reveal novel genes and mechanisms involved in scopolamine-induced amnesia, and demonstrate the involvement of both GABA and glutamate neurotransmission in this animal model of cognitive dysfunctions.     

Holeboard discrimination learning in mice

We have adapted to mice a holeboard-learning task, which allows simultaneous assessment of spatial working and reference-memory performance. The holeboard apparatus consists of an open-field chamber with a 16-hole floor insert. Across trials, animals have to learn that the same four holes of 16 are always baited. Here, we show that C57BL/6 mice readily acquire this task within 4 days when submitted to six trials per day or within 8 days when submitted to only four trials per day. We also show that C57BL/6, Swiss-Webster, CD-1 and DBA/2 mice acquire this task similarly, despite the fact that some differences could be observed in measures of exploratory activity during habituation and training. Moreover, the muscarinic antagonist scopolamine disrupts learning at doses of 0.1 and 1.0 mg/kg, although the highest dose appeared to have side-effects. Lastly, we found that amyloid precursor protein transgenic mice have a selective disruption in their working-memory performance only during reversal training (i.e. after a change in the configuration of the baited holes). Overall, our data indicate that this spatial learning task is well adapted to mice and will be useful to characterize spatial memory in various genetic or pharmacological mouse models.     

Influence of chitosan,acetic acid and citric acid on growth and tropane alkaloid production in transformed roots of Brugmansia candida Effect of medium pH and growth phase

The effects of chitosan, acetic acid and citric acid on production and release of hyoscyamine and scopolamine in hairy root cultures of Brugmansia candida were studied. Chitosan and acetic acid were tested at different concentrations and also at different media pH values. At pH 5.5, and at certain concentrations, acetic acid and chitosan increased the content of root scopolamine and hyoscyamine, and promoted the release of both alkaloids. Lowering the pH to 3.5 and 4.5 reduced the accumulation of both alkaloids in the roots, but at a pH of 4.5, their release increased significantly. Acetic and citric acid stimulated the release of scopolamine and hyoscyamine. This revised version was published online in June 2006 with corrections to the Cover Date.