Protective effect of Cnestis ferruginea and its active constituent on scopolamine-induced memory impairment in mice: A behavioral and biochemical study

Abstract

Context: Cnestis ferruginea Vahl ex DC (Connaraceae) (CF) is used in traditional African medicine in the management of CNS disorders. The degeneration and dysfunction of cholinergic neurons is closely associated with the cognitive deficits of Alzheimer’s disease (AD) and oxidative stress has been implicated in its pathogenesis. However, the influence of C. ferruginea on the cholinergic system and oxidative stress parameters has not been explored.

Objective: The present study investigates the effect of methanol root extract of C. ferruginea and its active constituent amentoflavone (CF-2) on memory, oxidative stress and acetylcholinesterase (AChE) activity in scopolamine-induced amnesia.

Materials and methods: Mice were orally treated with CF (25–200?mg/kg), CF-2 (6.25–25?mg/kg) for three days and memory impairment was induced by intraperitoneal injection of scopolamine (3?mg/kg). Memory function was evaluated by passive avoidance and Morris water maze tests. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain after the completion of behavioral studies.

Results: Scopolamine caused memory impairment along with increased AChE activity and oxidative stress in mice brain. Oral administration of CF and CF-2 significantly prevented scopolamine-induced memory impairment, inhibited AChE and enhanced antioxidant enzyme activity in the brain following scopolamine injection as compared to vehicle administration in scopolamine (i.p.)-treated mice that were comparable to the effect of tacrine.

Discussion and conclusion: The study demonstrated that C. ferruginea and its constituent have significant protective effect against scopolamine-induced memory deficits in mice that can be attributed to their antioxidant and antiAChE activity.     

银杏叶提取物对东莨菪碱所致大鼠空间工作记忆障碍的影响

目的探讨银杏叶提取物对东莨菪碱所致大鼠空间工作记忆障碍的影响。方法大鼠随机分成3组:正常组、东莨菪碱组和银杏叶治疗组。水迷宫试验,东莨菪碱组按0.4mg/kg腹腔注射,以后每天注射等体积生理盐水,连用6d。正常对照组每天注射与东莨菪碱等体积的生理盐水连用6d;银杏叶治疗组按10mg/kg腹腔注射,1次/d,连用6d。1周后进行Morris水迷宫试验,观察3组大鼠平台逃避潜伏期,并与实验后第1天比较。结果两次逃避潜伏期在正常组呈非常显著性差异(46.4±17.7,13.4±8.2,P<0.01)东莨菪碱组无统计学差异(23.6±14.3,18.1±9.8,P>0.05),银杏叶组呈显著性差异(27.9±14.3,9.0±3.8,P<0.05)。结论M-型胆碱能受体阻滞剂东莨菪碱能损害大鼠空间工作记忆,银杏叶提取物能改善这种损害,说明银杏叶提取物是通过影响胆碱能系统来发挥其促智作用的。     

羟基查尔酮类衍生物C8对东莨菪碱致痴呆小鼠学习记忆的影响

目的：观察羟基查尔酮类衍生物C8对东莨菪碱诱导的记忆障碍小鼠学习记忆的影响。方法：实验小鼠除空白对照组、东莨菪碱组（模型组）灌服0.5%CMC-Na溶液外,C8给药组（高、低2个剂量组）灌服C8,阳性对照组灌服吡拉西坦,连续灌胃22d。从第15天起进行Morris水迷宫试验,连续8d。结果：C8能明显缩短定位航行实验中模型小鼠的逃避潜伏期,明显延长空间探索实验中模型小鼠在原平台所在象限的游泳时间。结论：C8对东莨菪碱引起的小鼠学习记忆能力障碍有改善作用。     

Flumazenil and tacrine increase the effectiveness of ondansetron on scopolamine-induced impairment of spatial learning in rats

Rationale Cholinergic receptor blockade produces memory deficits in animal models. These deficits can be prevented by 5-HT₃ receptor antagonists, such as ondansetron, which increases acetylcholine release. We investigated the effects on cognitive performance of combined treatments of ondansetron with either flumazenil, a GABA_A receptor benzodiazepine site antagonist, or tacrine, a cholinesterase inhibitor, which are also able to prevent scopolamine-induced cognitive impairment.Methods Spatial learning and memory was assessed by studying the effects of single and combined treatments on acquisition and retention of the Morris water maze task in rats.Results Scopolamine (0.6 mg/kg) induced significant learning and retention deficits. Both ondansetron (0.1 g/kg) and tacrine (3 mg/kg) partially prevented the scopolamine-induced learning deficit. A full reversal was only found after the combined treatment of ondansetron with flumazenil (10 mg/kg) and also after tacrine in combination with ondansetron. Likewise, scopolamine-induced retention deficit was fully counteracted by the combined treatment of ondansetron with either flumazenil or tacrine, and only partially by any of the single treatments tested.Conclusions The scopolamine-induced impairment of learning and retention in the water maze is fully prevented by ondansetron when given in combination with either flumazenil or tacrine, suggesting that both combined treatments result in a potentiated cholinergic function and may constitute the basis of a new therapy for cognitive disorders.     

The protective effect of metformin in scopolamine-induced learning and memory impairment in rats

BackgroundAlzheimer's disease (AD) is the most common neurodegenerative disease in the world. One of the most commonly prescribed oral antidiabetic drug, metformin, has been shown to have beneficial effects on restoring impaired cognitive function. In the present study, we investigated the effects of metformin on spatial memory in terms of alleviating scopolamine-induced learning and memory impairments in rats by using the Morris water maze (MWM) test and the modified elevated plus-maze (mEPM) test. Furthermore, we investigated the possible mechanisms of action of metformin in preventing cognitive dysfunction.MethodsMale Wistar rats received metformin (50, 100, or 200 mg/kg/day) via gavage feeding for three weeks. Scopolamine was administered intraperitoneally before the probe step of the MWM test or the acquisition session of the mEPM test.ResultsThe learning and memory impairment induced by scopolamine was reversed by metformin. In addition, metformin improved the level of phosphorylated AMP-activated protein kinase and cAMP responsive element binding protein. However, metformin pretreatment had no impact on inhibiting the scopolamine-induced changes in acetylcholine levels. Furthermore, metformin exerted its antioxidant effect by significantly reversing scopolamine-induced changes in malondialdehyde, total antioxidant status, and superoxide dismutase levels in the hippocampus.ConclusionOur results indicate that one of the most commonly used antidiabetic drug, metformin, has the potential to prevent the development of dementia and be a novel therapeutic drug for the amelioration of cognitive dysfunction in AD.     

七氟醚麻醉对新生鼠学习与记忆的影响

目的 探索用七氟醚麻醉发育期小鼠是否会引起成长过程中学习记忆障碍。 方法 实验包括122只新生鼠(出生后7 d)。其中72只分别经七氟醚1.0或0.5最低肺泡有效浓度(minimum alveolar concentration,MAC)麻醉或吸入40% O₂ 2 h,4周或12周行水迷宫实验,记录训练各天潜伏期和游泳速度,以及探索期平台滞留时间和平台穿越次数。另外50只小鼠用于测定七氟醚麻醉(1.0或0.5 MAC)过程(0、1、2 h)中动脉血血气分析。 结果 新生鼠在整个麻醉过程中,pH值、PaCO₂、PaO₂和SaO₂均保持稳定,P>0.05。麻醉后4周,训练期后3 d,对照组小鼠潜伏期明显低于麻醉组,且后2 d,0.5 MAC组小鼠的潜伏期明显短于1.0 MAC组。探索期,对照组小鼠平台停留时间和平台穿越次数均明显高于2组麻醉组。麻醉后12周,1.0 MAC组小鼠在训练第5天潜伏期仍明显延长。探索期,对照组小鼠平台停留时间和(或)平台穿越次数均明显高于麻醉组。 结论 七氟醚麻醉引起新生鼠成长过程中学习与记忆障碍,其程度与药物浓度有关,且随时间推移减弱。     

Effects of rolipram on scopolamine-induced impairment of working and reference memory in the radial-arm maze tests in rats

RATIONALE: Rolipram, a selective inhibitor of cyclic AMP-specific phosphodiesterase (PDE4), has been shown to enhance scopolamine-induced impairment of working memory. However, its effect on reference memory, which appears to be related to the level of cyclic AMP (cAMP), has not been investigated yet; in addition, the mechanism involved in its effects on memory remains to be elucidated. OBJECTIVES: To investigate the effects of rolipram on working and reference memories impaired by scopolamine and the involvement of cAMP. METHODS: By administration (IP) of rolipram and forskolin, an activator of adenylyl cyclase (AC), the effects of both drugs on the number of correct choices and errors in experiment 1 and, the frequency of both working memory errors and reference memory errors in experiment 2 were observed in two eight-arm radial maze tasks in rats. RESULTS: In experiment 1, rolipram (0.01-1.0 mg/kg) attenuated the scopolamine-induced (0.5 mg/kg) increase in the total number of errors in dose- and time-dependent manners. The minimum effective dose of rolipram was 0.05 mg/kg and the effects lasted nearly 60 min. By contrast, forskolin (1.0-10.0 mg/kg) failed significantly to affect any of the above indices altered by scopolamine. In experiment 2, rolipram (0.05 and 0.1 mg/kg) decreased the frequencies of both working and reference memory errors that were elevated by scopolamine. Forskolin did not alter either type of error at a dose that increased the exploration time. CONCLUSION: Rolipram may exert its effects of reversing both working and reference memory impairments via increased cyclic AMP concentrations in certain signal transduction pathways, rather than by a generalized increase in cAMP.     

TRH attenuates scopolamine-induced memory impairment in humans

The brain tripeptide thyrotropin-releasing hormone (TRH) has been demonstrated to facilitate cholinergic neurotransmission. To test its interaction with the cholinergic system in humans, high-dose TRH (0.5 mg/kg) or placebo was administered intravenously (IV) to normal controls pretreated with scopolamine (0.5–0.75 mg IV), a centrally active muscarinic antagonist, which has been used to model aspects of the memory impairment of normal aging and of dementia. Compared to placebo, TRH markedly attenuated scopolamine-induced impairment of some measures of memory, most notably on a selective reminding task. This cognitive study is the first in humans to suggest a neuromodulatory effect of a peptide on the cholinergic system, and suggests a facilitatory role for TRH in human memory processes.     

Effects of ethylcholine aziridinium,scopolamine and morphine on learning behaviors in morris water maze

To assess the learning behaviors of the various chemicals, such as ethylcholine aziridinium (AF64A), scopolamine and morphine, the chemicals were administered into either rat or mice. And water maze tests were performed before and during drug administration. In AF64A-treated groups (3 nmol/each ventricle), the latencies to escape was significantly increased in both of the pretraining- and posttraining groups. In scopolamine-treatment (2 mg/kg, sc) to the pretrained group, the latency to escape was significantly shortened after the acute administration of scopolamine. However in subacute treatment group with scopolamine, the latency to escape was significantly increased. In morphine-treated groups (10 mg/kg, ip), the latency to escape was significantly increased after the acute administration. However in subacute treatmment with morphine, the latency to escape was not changed. The results indicate that each chemical induces the learning impairment. However the chemical-induced learning impairment may have different characteristics upon the exposed chemical. Also the results suggest that both the motivation and the retrieval of memory might be impaired by AF64A.     

丁香酚吸嗅对血管性痴呆模型大鼠学习记忆障碍改善的实验研究

目的研究丁香酚吸嗅对血管性痴呆(vascular dementia,VD)大鼠学习障碍的影响。方法成年雄性SD大鼠32只随机分成4组:VD模型组,丁香酚治疗组,假手术组和正常对照组,每组8只。VD模型组用改良的双侧颈总动脉加扎法造模;丁香酚治疗组大鼠在造模完成后3 d予以1%浓度的丁香酚吸嗅;假手术组除不结扎血管外,余下操作步骤同VD模型组,空白组不做任何处理。在术前和术后60 d时,用Morris水迷宫测定大鼠的空间学习记忆能力。结果 Morris水迷宫实验中,术前各组大鼠的逃避潜伏期及穿台次数差异无统计学意义(P0.05);术后60 d时,VD模型组大鼠的逃避潜伏期明显延长、穿台次数明显减少,与正常对照组和假手术组相比差异有统计学意义(P0.05);丁香酚治疗组大鼠逃避潜伏期明显短于VD模型组,穿台次数多于VD模型组,差异有统计学意义(P0.05)。结论丁香酚吸嗅可改善VD模型大鼠的学习记忆障碍。     

Caffeine attenuates scopolamine-induced memory impairment in humans

Caffeine consumption can be beneficial for cognitive functioning. Although caffeine is widely recognized as a mild CNS stimulant drug, the most important consequence of its adenosine antagonism is cholinergic stimulation, which might lead to improvement of higher cognitive functions, particularly memory. In this study, the scopolamine model of amnesia was used to test the cholinergic effects of caffeine, administered as three cups of coffee. Subjects were 16 healthy volunteers who received 250 mg caffeine and 2 mg nicotine separately, in a placebo-controlled double-blind cross-over design. Compared to placebo, nicotine attenuated the scopolamine-induced impairment of storage in short-term memory and attenuated the scopolamine-induced slowing of speed of short-term memory scanning. Nicotine also attenuated the scopolamine-induced slowing of reaction time in a response competition task. Caffeine attenuated the scopolamine-induced impairment of free recall from short- and long-term memory, quality and speed of retrieval from long-term memory in a word learning task, and other cognitive and non-cognitive measures, such as perceptual sensitivity in visual search, reading speed, and rate of finger-tapping. On the basis of these results it was concluded that caffeine possesses cholinergic cognition enhancing properties. Caffeine could be used as a control drug in studies using the scopolamine paradigm and possibly also in other experimental studies of cognitive enhancers, as the effects of a newly developed cognition enhancing drug should at least be superior to the effects of three cups of coffee.     

Agmatine, a metabolite of L-arginine, reverses scopolamine-induced learning and memory impairment in rats

Agmatine (l-amino-4-guanidino-butane), a metabolite of L-arginine through the action of arginine decarboxylase, is a novel neurotransmitter. In the present study, effects of agmatine on cognitive functions have been evaluated by using one trial step-down passive avoidance and three panel runway task. Agmatine (20, 40, 80 mg/kg i.p.) was administered either in the presence or absence of a cholinergic antagonist, scopolamine (1 mg/kg i.p.). Scopolamine significantly impaired learning and memory in both passive avoidance and three panel runway test. Agmatine did not affect emotional learning, working and reference memory but significantly improved scopolamine-induced impairment of learning and memory in a dose dependent manner. Our results indicate that agmatine, as an endogenous substance, may have an important role in modulation of learning and memory functions.     

Effect of pregabalin on fear-based conditioned avoidance learning and spatial learning in a mouse model of scopolamine-induced amnesia

Objectives: Cognitive deficits are one of the frequent symptoms accompanying epilepsy or its treatment.

Methods: In this study, the effect on cognition of intraperitoneally administered antiepileptic drug, pregabalin (10?mg/kg), was investigated in scopolamine-induced memory-impaired mice in the passive avoidance task and Morris water maze task. The effect of scopolamine and pregabalin on animals’ locomotor activity was also studied.

Results: In the retention phase of the passive avoidance task, pregabalin reversed memory deficits induced by scopolamine (p?p?p?p?Discussion: In passive avoidance task, pregabalin reversed learning deficits induced by scopolamine. In the Morris water maze, pregabalin did not influence spatial learning deficits induced by scopolamine. These results are relevant for epileptic patients treated with pregabalin and those who use it for other therapeutic indications (anxiety, pain).     

Donepezil primarily attenuates scopolamine-induced deficits in psychomotor function, with moderate effects on simple conditioning and attention, and small effects on working memory and spatial mapping

Rationale Alzheimer’s dementia (AD) patients have profound deficits in cognitive and social functions, mediated in part by a decline in cholinergic function. Acetylcholinesterase inhibitors (AChEI) are the most commonly prescribed treatment for the cognitive deficits in AD patients, but their therapeutic effects are small, and it is still not clear if they primarily affect attention, memory, or some other cognitive/behavioral functions.Objectives The objective of the present experiments was to explore the effects of donepezil (Aricept™), an AChEI, on behavioral deficits related exclusively to cholinergic dysfunction.Materials and methods The effects of donepezil were assessed in Sprague–Dawley rats with scopolamine-induced deficits in a battery of cognitive/behavioral tests.Results Scopolamine produced deficits in contextual and cued fear conditioning, the 5-choice serial reaction time test, delayed nonmatching to position, the radial arm maze, and the Morris water maze. Analyses of the pattern and size of the effects revealed that donepezil produced very large effects on scopolamine-induced deficits in psychomotor function (∼20–50% of the variance), moderate-sized effects on scopolamine-induced deficits in simple conditioning and attention (∼3–10% of the variance), but only small effects on scopolamine-induced deficits in higher cognitive functions of working memory and spatial mapping (∼1% of the variance).Conclusions These results are consistent with the limited efficacy of donepezil on higher cognitive function in AD patients, and suggest that preclinical behavioral models could be used not only to determine if novel treatments have some therapeutic potential, but also to predict more precisely what the pattern and size of the effects might be.Electronic supplementary material Supplementary material is available for this article at and is accessible for authorized users.     

胰岛素对AD样小鼠学习记忆的影响及其机制

【摘要】目的 研究胰岛素对阿尔茨海默病（AD）样小鼠学习记忆能力的影响及其机制。方法 将21只小鼠随机分为对照(CON) 组、模型（链脲佐菌素,STZ）组和胰岛素治疗(INS) 组,每组7只,后2组小鼠脑室内注射STZ建立 AD模型,INS组小鼠皮下注射胰岛素持续30 d。Morris水迷宫检测小鼠学习记忆能力,Western blotting检测Tau和神经丝（NFs）蛋白的磷酸化水平,荧光染料Fluoro-Jade B（FJB）标记退化神经元。结果 与CON组相比,STZ组小鼠平均逃避潜伏期和路径长度明显增加(P < 0.05)、穿越隐匿平台次数明显减少(P < 0.05),小鼠脑内Tau蛋白在Ser199/ 202、Ser396/404、Thr212和Thr205位点的磷酸化水平以及NFs蛋白的磷酸化增加(P < 0.05),FJB标记的小鼠海马CA1 区平均累积光密度(IOD)较CON组明显增加(P < 0.001);与STZ组相比,INS组小鼠学习记忆改善,逃避潜伏期和路径长度明显减少(P < 0.05)、穿越隐匿平台次数明显增加(P < 0.05),Tau蛋白特异性位点和NFs蛋白的磷酸化作用明显降低(P < 0.05),FJB标记的小鼠海马CA1区平均累积分光密度(IOD)明显减少(P < 0.001)。结论 胰岛素能改善STZ脑室内注射的AD样小鼠学习记忆减退,可能与降低Tau和NFs蛋白的过度磷酸化和神经细胞退行性变有关。     

Reversal of scopolamine-induced amnesia by phosphatidylserine in rats

Scopolamine (2 mg/kg IP) and propranolol (55 mg/kg IP), given before a single learning trial, reduce retention of a passive avoidance response in rats. Phosphatidylserine, 30–60 mg/kg IP, antagonizes the amnesic effect of scopolamine but not that of propranolol. The retention of the passive avoidance response is not affected by phosphatidylserine given alone. The results indicate that this phospholipid selectively counteracts the action of scopolamine on passive avoidance acquisition, probably via a cholinergic mechanism.     

The novel nootropic compound DM232 (UNIFIRAM) ameliorates memory impairment in mice and rats

The favorable pharmacological profile exhibited by piracetam stimulated the synthesis of related compounds potentially endowed with a higher nootropic potency. The antiamnesic and procognitive activity of DM232 (unifiram), a new compound structurally related to piracetam, was investigated. Mouse passive avoidance and rat Morris water maze and Social learning tests were employed. DM232 (0.001–1 mg kg^?1 i.p. – 0.01–0.1 1 mg kg^?1 p.o.) prevented amnesia induced by scopolamine (1.5 mg kg^?1 i.p.), mecamylamine (20 mg kg^?1 i.p.), baclofen (2 mg kg^?1 i.p.), and clonidine (0.125 mg kg^?1 i.p.). Furthermore, The antiamnesic effect of the investigated compound was comparable to that exerted by well‐known nootropic drugs such as piracetam (30–100 mg kg^?1 i.p.), aniracetam (100 mg kg^?1 p.o.), rolipram (30 mg kg^?1 p.o.), and nicotine (5 mg kg^?1 i.p). DM232 (0.1 mg kg^?1 i.p.) was also able to prevent amnesia induced by scopolamine (0.8 mg kg^?1 i.p.) in the rat Morris watermaze test. In the rat social learning test, DM232 (0.1 mg kg^?1 i.p.) injected in adults rats reduced the duration of active exploration of the familiar partner in the second session of the test. DM232, similarly to piracetam, reduced the duration of hypnosis induced by pentobarbital. At the highest effective doses, the investigated compound did not impair motor coordination (rota rod test), nor modified spontaneous (Animex). These results indicate DM232 (unifiram) as a novel cognition enhancer, strictly related to piracetam‐like compounds, able to ameliorate memory impairment at doses about 1,000 times lower than the most active available nootropic compounds. Drug Dev. Res. 56:23–32, 2002. © 2002 Wiley‐Liss, Inc.     

Effects of olanzapine, sertindole and clozapine on learning and memory in the Morris water maze test in naive and MK-801-treated mice

Cognitive dysfunction in schizophrenia is associated with functional disease symptoms. The beneficial effects of second generation antipsychotic drugs on cognitive function in schizophrenic patients are controversial. In this study, we investigated the effects of the second generation antipsychotics olanzapine, sertindole and clozapine on cognitive function in the Morris water maze task in naive or MK-801-treated animals. Male balb-c mice were treated subchronically with olanzapine (1.25, 2.5 and 5 mg/kg, i.p.), sertindole (0.63, 1.3, 2.5 mg/kg, s.c.) or clozapine (0.5 and 1 mg/kg, i.p.), and cognitive deficits were induced by MK-801 (0.2 mg/kg, i.p.) administration. Water maze performance was expressed as escape latency to find the hidden platform, the time spent in target quadrant, the mean distance to platform and the swim speed. In naive mice olanzapine impaired water maze performance, whereas sertindole and clozapine had no effect while the MK-801-induced cognitive impairment was reversed by the second generation antipsychotics — olanzapine, sertindole and clozapine at the doses used. These results revealed that while olanzapine had some disturbing effects on cognitive functions in naive animals; olanzapine, sertindole and clozapine might improve cognitive deficits in schizophrenic patients.     

人参皂苷Re对小鼠学习记忆障碍的作用

人参(Radix gingseng)是五加科人参属植物人参Panax ginseng CA Meyer的干燥根,具有广泛的药理作用.从人参中分离出的人参皂苷被认为是人参促智和延缓衰老作用的主要有效成分之一,已有实验证明[1]人参皂苷中的Rg1和Rb1具有改善记忆的效果,而人参皂苷中含量较高的Re也具有人参总皂苷的某些活性,本实验对人参皂苷Re对小鼠学习记忆障碍的改善及其作用机制进行了探讨.     

康寿灵对东莨菪碱痴呆模型大鼠学习记忆的保护作用

目的：观察康寿灵对东莨菪碱诱导的记忆障碍大鼠学习记忆的影响，并探讨其可能的作用机制。方法：各组大鼠分别用生理盐水（正常对照组、模型组）、康寿灵（低、中、高剂量组）和石杉碱甲（阳性对照组）灌胃37d。第31天起进行Morris水迷宫行为测试，连续7d。行为测试结束后，进行大鼠脑组织丙二醛（MDA）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）及ATPase活性测定。结果：预先给予大鼠康寿灵30d可改善东莨菪碱导致的记忆障碍，使大鼠脑组织中抗氧化酶SOD、GSH-Px及ATPase活性升高，而MDA含量降低。结论：康寿灵对东莨菪碱引起的大鼠学习记忆能力障碍有明显保护作用，其作用机制可能与抗氧化作用密切相关。