Imperatorin ameliorates learning and memory deficits through BDNF/TrkB and ERK/CaMKIIα/CREB signaling in prenatally‐stressed female offspring

Prenatal stress (PS) can lead to impaired spatial learning and memory in offspring. Imperatorin (IMP) is a naturally occurring furanocoumarin with many pharmacological properties. However, the effects of IMP on cognitive impairment induced by PS and the underlying molecular mechanisms remain unclear. We investigated the protective effect of IMP treatment after PS on learning and memory deficits in female offspring at postnatal 60 days. After treating prenatally‐stressed offspring with IMP (15 and 30 mg/kg) for 28 days, we found that IMP increased body weight and ameliorated spatial learning and memory and working memory deficits in female offspring rats. Meanwhile, hippocampal Glu and serum corticosterone levels in prenatally‐stressed offspring were significantly decreased after IMP administration. Additionally, IMP treatment significantly increased BDNF, TrkB, CaMKII, and CREB mRNA expression in the hippocampus of offspring rats. Furthermore, PS‐mediated induction of RKIP protein and mRNA expression and glucocorticoid receptor protein expression in the hippocampus of offspring rats were significantly decreased by IMP treatment, and the protein expression of BDNF and TrkB and relative levels of p‐EKR/ERK, p‐CaMKIIα/CaMKIIα, and p‐CREB/CREB were remarkably increased after IMP treatment. Taken together, IMP can ameliorate PS‐induced learning and memory deficits through BDNF/TrkB and ERK/CaMKIIα/CREB signaling pathway and hypothalamic–pituitary–adrenal axis.     

ACUPUNCTURE STIMULATION IMPROVES MEMORY IMPAIRMENT INDUCED BY SCOPOLAMINE IN RATS

Objective: The purpose of this study was to examine whether acupuncture stimulation at the Baihui(GV20) improves memory defects caused by administration of scopolamine(SCO) to the rats.The effects of acupuncture stimulation at the GV20 on the cholinergic system as well as the expression of brain-derived neurotrophic factor(BDNF) and cAMP-response element-binding protein(CREB) in the hippocampus were also investigated.Methods: Male rats were administered with SCO(2 mg/kg, i.p.) once daily for 14 days.Acupuncture stimulation at GV20 was performed for 5 min before SCO injection.Results: Acupuncture stimulation at GV20 improved memory impairment as measured by the passive avoidance test(PAT) and reduced the escape latency for finding the platform in the Morris water maze(MWM) test.Acupuncture stimulation at the GV20 significantly alleviated memory-associated decreases in the expression levels of choline acetyltransferase(ChAT), BDNF and CREB proteins in the hippocampus.Additionally, acupuncture stimulation at the GV20 significantly restored the expression of choline transporter 1(CHT1), vesicular acetylcholine transporter(VAChT), BDNF and CREB mRNAs in the hippocampus.Conclusion: These results demonstrated that acupuncture stimulation at the GV20 has significant neuroprotective effects against neuronal impairment and memory dysfunction caused by SCO in rats.Thus, these findings suggested that acupuncture stimulation at the GV20 might be a useful therapy in various neurodegenerative diseases for the improvement of cognitive functioning via stimulating cholinergic enzyme activities and regulating BDNF and CREB expression in the brain.     

Brain‐derived Neurotrophic Factor Signaling Mediates the Antidepressant‐like Effect of the Total Flavonoids of Alpiniae Oxyphyllae Fructus in Chronic Unpredictable Mild Stress Mice

The present study verified the antidepressant‐like effects of the total flavonoids of Alpinia oxyphylla Miq. (AOF) using the chronic unpredictable mild stresses paradigm and explored the mechanism that underlies antidepressant‐like effects of AOF in mice. Previous research has shown that tropomyosin‐related kinase B (TrkB) receptor‐mediated extracellular regulated protein kinases (ERK) signaling pathways participate in depression pathophysiology. Therefore, we aimed to explore whether AOF improved depression‐like behaviors by increasing activity of ERK pathways mediated by TrkB. Results showed that AOF significantly reduced the immobility time in the forced swimming test and increased the sucrose preference in sucrose preference test. In addition, decreased phosphorylated cyclic adenosine monophosphate response element‐binding protein (pCREB)/CREB, pERK/ERK, and pTrkB/TrkB levels in the hippocampus induced by chronic unpredictable mild stresses were reversed by intragastric administration of AOF. Results suggested that AOF increased pCREB/CREB, pERK/ERK, and pTrkB/TrkB levels by acting on the TrkB receptor. To verify this hypothesis, mice were pretreated with the TrkB inhibitor K252a (or 0.1% dimethyl sulfoxide, intraperitoneally, 2 weeks), before the intragastric administration of AOF. This resulted in an absence of antidepressant‐like effects, as well as no activation of pERK/pCREB/BDNF signaling pathways. Results demonstrated that AOF might exert antidepressant‐like effects by targeting TrkB receptor‐mediated pERK/pCREB/BDNF signal systems, which could help to identify the AOF receptor. Copyright © 2016 John Wiley & Sons, Ltd.     

Rapid antidepressant‐like effect of Fructus Aurantii depends on cAMP‐response element binding protein/Brain‐derived neurotrophic facto by mediating synaptic transmission

Several studies reported the relative antidepressant effects of Fructus Aurantii (FRA) with repeated treatment, the rapid antidepressant effects of FRA and the underlying mechanisms remained unclear. We, therefore, examined the rapid antidepressant actions of FRA in behavioral tests in mice and tested the underlying molecular mechanisms. We found FRA, like ketamine, reversed the behavioral deficits both in lipopolysaccharide(LPS)‐induced and learned helplessness (LH) models at 1 day after a single administration. FRA was also capable of increasing the expressions of protein kinase A/cAMP‐response element‐binding protein/brain‐derived neurotrophic factor (PKA/CREB/BDNF) signaling in hippocampus. Consistent with ketamine, FRA up‐regulated the expressions of GABAergic receptor (GAD67) and glutamatergic receptor 1 (GluR1) in mouse hippocampus both exposed to LPS and LH. Moreover, synaptic proteins such as postsynaptic density‐95 (PSD95) and synapsin1 were also up‐regulated by a single dose of FRA both in LH and LPS models, like ketamine. Finally, metadoxine (an antagonist of CREB) inhibited the antidepressant effects of FRA in tail suspension test (TST) and forced swimming test (FST) in LPS‐induced mice, which also blocked the phosphorylation of CREB and the expressions of neurotransmitters and synaptic molecules. Therefore, FRA had rapid antidepressant effects, which depended on PKA/CREB/BDNF pathway, subsequently regulated the downstream synaptic transmission.     

Ginsenosides Rg5 and Rh3 protect scopolamine-induced memory deficits in mice

Ethnopharmacological relevance

Panax ginseng (family Araliaceae) is traditionally used as a remedy for cancer, inflammation, stress and aging.

Aim of study

To explore whether ginsenosides Rg5 and Rh3, the main constituents of heat-processed ginseng (the root of Panax ginseng), could protect memory deficit.

Materials and methods

We isolated ginsenosides Rh3 and Rg5 from heated-processed ginseng treated with and without human feces, respectively. Then we investigated their protective effects on memory impairment using the passive avoidance, Y-maze and Morris water maze tasks in mice. Memory deficit was induced in mice by the intraperitoneal injection of scopolamine.

Results

Ginsenosides Rg5 or Rh3 increased the latency time reduced by scopolamine in passive avoidance test. Treatment with ginsenoside Rg5 or Rh3 significantly reversed the lowered spontaneous alteration induced by scopolamine in Y-maze task. Ginsenoisde Rg5 or Rh3 (10 mg/kg) significantly shortened the escape latencies prolonged by treatment with scopolamine on the last day of training trial sessions in Morris water maze task. Furthermore, ginsenosides Rg5 and Rh3 inhibited acetylcholinesterase activity in a dose-dependent manner, with IC₅₀ values of 18.4 and 10.2 μM, respectively. The inhibitory potency of ginsenoside Rh3 is comparable with that of donepezil (IC₅₀=9.9 μM). These ginsenosides also reversed hippocampal brain-derived neurotrophic factor (BDNF) expression and cAMP response element-binding protein (CREB) phosphorylation reduced by scopolamine. Of them, ginsenoside Rh3 more potently protected memory deficit.

Conclusions

Ginsenoside Rg5 and its metabolite ginsenoside Rh3 may protect memory deficit by inhibiting AChE activity and increasing BDNF expression and CREB activation.     

逍遥散抗抑郁作用的BDNF/CREB信号机制

目的:探讨逍遥散抗抑郁作用的BDNF/CREB信号机制。方法:采用小鼠慢性温和不可预知应激(CUMS)结合孤养抑郁模型,逍遥散水煎液30g/kg灌胃给药4周,测定小鼠体重、自主活动及糖水消耗量的变化以评价药物的抗抑郁效应。ELISA法测定血清BDNF水平,实时荧光定量聚合酶链式反应(real-time PCR)测定小鼠海马及皮质部位CREB、BDNF mRNA表达,Western-blot方法测定小鼠脑内ERK1/2及磷酸化ERK1/2(pERK1/2)的蛋白表达量。结果:与模型组比较,逍遥散30g/kg能提高模型小鼠体重、自主活动及糖水消耗量,并有提高模型动物血清BDNF含量的趋势;逍遥散30g/kg显著增加模型小鼠海马BDNF、CREB mR-NA及皮质BDNF mRNA的表达量,对模型动物海马部位pERK1/2的表达量有提高趋势。结论:逍遥散对CUMS结合孤养的小鼠抑郁模型具有抗抑郁效应,作用机制与干预BDNF/CREB信号途径的关键分子的表达与功能有关。     

Kaempferide prevents cognitive decline via attenuation of oxidative stress and enhancement of brain‐derived neurotrophic factor/tropomyosin receptor kinase B/cAMP response element‐binding signaling pathway

Kaempferide (KF) is a compound of flavonoids from Alpinae oxyphylla Miq, and the herb itself is used as a classical tonic agent. This paper aims to investigate the effects of KF on cognitive function impairment and neurodegeneration in the mouse model of Alzheimer's disease induced by intracerebroventricular (ICV) injection of Aβ_1–42. The mice were treated with KF at doses of 0.02 and 0.2 mg/kg/day (ICV) for five consecutive days after Aβ_1–42 exposures. The behavioral test results showed that KF could prevent cognitive decline in mice induced by Aβ_1–42 as assessed by the locomotor activity test, Y‐maze test, and Morris water maze test. Furthermore, the activities of superoxide dismutase and malondialdehyde in the hippocampus and cerebral cortex were elevated by KF administration. Results of hippocampus slices showed that neurons were integrated and regularly arranged in the groups, which were administered along with KF. In addition, we found KF could boost brain‐derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)/cAMP response element‐binding (CREB) protein signal in the hippocampus. All results illustrated that KF could exert neuroprotective effects at least partly through alleviating oxidative stress and enhancing the BDNF/TrkB/CREB pathway in Aβ_1–42‐induced mice.     

Protective effects of Genistein on the cognitive deficits induced by chronic sleep deprivation

Sleep deprivation has been widely reported to cause cognitive dysfunction, and elevation in oxidative stress and inflammation in the body, including the brain, have been suggested as the main factors. Genistein (GE) is an isoflavone widely present in leguminous plants, and it was found to exert a wide spectrum of biological activities, including antioxidant, anti‐inflammatory, hepatoprotective, neuroprotective, and antimetastatic effects. In this study, the protective effect of GE on chronic sleep deprivation (CSD)‐induced cognitive dysfunction was investigated. The mice were subjected to the sleep interruption apparatus and continuously sleep deprived for 25 days. GE was orally administrated (10, 20, and 40 mg/kg) during the sleep deprivation process totally for 25 days. Cognitive behavioral tests were conducted to study the learning and memory using the object location recognition (OLR) task, novel object recognition (NOR) test, and the Morris water maze (MWM) task. Additionally, the cortex and hippocampus were dissected to measure the oxidative stress markers and the antioxidant element nuclear erythroid‐2‐related factor 2 (Nrf2) and its downstream targets, including glutamate cysteine ligase catalytic, glutamate cysteine ligase modifier, heme oxygenase 1, and quinone oxidoreductase 1, as well as nuclear factor kappa B (NF‐κB) p65, nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX‐2) protein expression. Moreover, the pro‐inflammatory cytokines (TNF‐α, interleukin [IL]‐6, and IL‐1β) level was examined in the serum. The current results showed that GE could dose‐dependently ameliorate the cognitive deficits of CSD‐treated mice in the OLR, NOR, and MWM tasks. In addition, GE treatment significantly elevated the activities of total antioxidant capacity and superoxide dismutase and the level of glutathione and lowered the content of malondialdehyde in the cortex and hippocampus of CSD‐treated mice. Furthermore, GE administration effectively activated the antioxidant element Nrf2 and its downstream targets in the cortex and hippocampus of CSD‐treated mice. Moreover, GE treatment significantly suppressed CSD‐induced NF‐κB p65, iNOS, and COX‐2 activation in the cortex and hippocampus, as well as inhibited CSD‐induced pro‐inflammatory cytokines (TNF‐α, IL‐6, and IL‐1β) release in the serum. Taken together, all these results suggested that GE has substantial potential as a therapeutic intervention for the alleviation of CSD‐induced deleterious effects.     

Neuroprotective effects of 20(S)‐protopanaxatriol (PPT) on scopolamine‐induced cognitive deficits in mice

20(S)‐protopanaxatriol (PPT), one of the ginsenosides from Panax ginseng, has been reported to have neuroprotective effects and to improve memory. The present study was designed to investigate the protective effect of PPT on scopolamine‐induced cognitive deficits in mice. Male Institute of Cancer Research mice were pretreated with 2 different doses of PPT (20 and 40 μmol/kg) for 27 days by intraperitoneal injection, and scopolamine (0.75 mg/kg) was injected intraperitoneally for 9 days to induce memory impairment. Thirty minutes after the last pretreatment, the locomotor activity was firstly examined to evaluate the motor function of mice. Then, memory‐related behaviors were evaluated, and the related mechanism was further researched. It was founded that PPT treatment significantly reversed scopolamine‐induced cognitive impairment in the object location recognition experiment, the Morris water maze test, and the passive avoidance task, showing memory‐improving effects. PPT also significantly improved cholinergic system reactivity and suppressed oxidative stress, indicated by inhibition of acetylcholinesterase activity, elevation of acetylcholine levels, increasing superoxide dismutase activity and lowering levels of malondialdehyde in the hippocampus. In addition, the expression levels of Egr‐1, c‐Jun, and cAMP responsive element binding in the hippocampus were significantly elevated by PPT administration. These results suggest that PPT may be a potential drug candidate for the treatment of cognitive deficit in Alzheimer's disease.     

Cognitive Ameliorating Effect of Acanthopanax koreanum Against Scopolamine‐Induced Memory Impairment in Mice

Acanthopanax koreanum Nakai (Araliaceae) is one of the most widely cultivated medicinal plants in Jeju Island, Korea, and the roots and stem bark of A. koreanum have been traditionally used as a tonic agent for general weakness. However, the use of A. koreanum for general weakness observed in the elderly, including those with declined cognitive function, has not been intensively investigated. This study was performed to investigate the effect of the ethanol extract of A. koreanum (EEAK) on cholinergic blockade‐induced memory impairment in mice. To evaluate the ameliorating effects of EEAK against scopolamine‐induced memory impairment, mice were orally administered EEAK (25, 50, 100, or 200 mg/kg), and several behavioral tasks, including a passive avoidance task, the Y‐maze, and a novel object recognition task, were employed. Besides, western blot analysis was conducted to examine whether EEAK affected memory‐associated signaling molecules, such as protein kinase B (Akt), Ca²⁺/calmodulin‐dependent protein kinase II (CaMKII), and cAMP response element‐binding protein (CREB). The administration of EEAK (100 or 200 mg/kg, p.o.) significantly ameliorated the scopolamine‐induced cognitive impairment in the passive avoidance task, the Y‐maze, and the novel object recognition task. The phosphorylation levels of both Akt and CaMKII were significantly increased by approximately two‐fold compared with the control group because of the administration of EEAK (100 or 200 mg/kg) (p < 0.05). Moreover, the phosphorylation level of CREB was also significantly increased compared with the control group by the administration of EEAK (200 mg/kg) (p < 0.05). The present study suggests that EEAK ameliorates the cognitive dysfunction induced by the cholinergic blockade, in part, via several memory‐associated signaling molecules and may hold therapeutic potential against cognitive dysfunction, such as that presented in neurodegenerative diseases, for example, Alzheimer's disease. Copyright © 2017 John Wiley & Sons, Ltd.     

Comparison of ginsenosides Rg1 and Rb1 for their effects on improving scopolamine‐induced learning and memory impairment in mice

Rg1 and Rb1 are two major active compounds of ginseng that facilitate learning and memory. The present study aimed to compare the nootropic effects of Rg1 and Rb1 in a scopolamine induced dementia mice model. After 6 and 12 mg/kg of Rg1 and Rb1 intraperitoneal administration to mice for 7 days, their effects were assessed using the step‐down passive avoidance (SD) and the Morris water maze (MWM) tests, the acetylcholinesterase (AChE) activity, acetylcholine (ACh) content and serotonin (5‐HT) level in the hippocampus were analysed after SD and MWM tests. The results showed that Rg1 and Rb1 ameliorated cognition‐deficiency in mice with dementia. Rg1 showed stronger effects than Rb1 on escape acquisition in MWM. Both Rg1 and Rb1 increased ACh levels in the hippocampus, but Rg1 inhibited AChE activity while Rb1 had no effect on AChE activity. Both Rg1 and Rb1 inhibited the decrease of 5‐HT induced by scopolamine, but Rb1 was more active than the same dose of Rg1. These results demonstrate that multiple administrations of Rg1 and Rb1 are effective in improving memory deficiency induced by scopolamine. Rg1 appears to be more potent than Rb1 in improving acquisition impairment, and the two ginsenosides may act through different mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.     

Schisandrae Chinensis Fructus inhibits behavioral deficits induced by sleep deprivation and chronic unpredictable mild stress via increased signaling of brain‐derived neurotrophic factor

The present study was undertaken to explore the interactions between sleep deprivation (SD) and Schisandrae Chinensis Fructus (SCF) treatment in the antidepressant‐like effects. We observed that SD aggravated the anxiety‐like behavior induced by chronic unpredictable mild stress (CUMS) in the elevated plus maze test. However, the forced swimming test and sucrose preference test showed that SD (12 hr) alleviated the depressive symptoms and SD (72 hr) has the opposite effects. Administration of SCF showed a promising therapeutic effect on depression and anxiety induced by CUMS and SD. Moreover, SCF could potential strengthen the antidepressant‐like effects of SD (12 hr) according to the behavioral tests. In addition, the BDNF level in hippocampus was elevated by SD (12 hr) and SCF treatment and together with the upregulation of TrkB/CREB/ERK and PI3K/AKT/GSK3β/mTOR signaling pathways. Besides, the protein levels of p70S6K and PSD95, which are downstream targets of mTOR, also increased by the treatment. These results indicated that the antidepressant‐like effect of SCF in the CUMS depends on the activation of BDNF and the modulation of TrkB/CREB/ERK and PI3K/AKT/GSK3β/mTOR signaling cascades, and SD (12 hr) shared a common etiology consisting of complex bidirectional interactions with SCF.     

Doxorubicin‐induced normal breast epithelial cellular aging and its related breast cancer growth through mitochondrial autophagy and oxidative stress mitigated by ginsenoside Rh2

Clinical dose of doxorubicin (100 nM) induced cellular senescence and various secretory phenotypes in breast cancer and normal epithelial cells. Herein, we reported the detailed mechanism underlying ginsenoside Rh2‐mediated NF‐κB inhibition, and mitophagy promotion were evaluated by antibody array assay, western blotting analysis, and immunocytostaining. Ginsenoside Rh2 suppressed the protein levels of TRAF6, p62, phosphorylated IKK, and IκB, which consequently inactivated NF‐κB activity. Rh2‐mediated secretory phenotype was delineated by the suppressed IL‐8 secretion. Senescent epithelial cells showed increased level of reactive oxygen species (ROS), which was significantly abrogated by Rh2, with upregulation on SIRT 3 and SIRT 5 and subsequent increase in SOD1 and SOD2. Rh2 remarkably favored mitophagy by the increased expressions of PINK1 and Parkin and decreased level of PGC‐1α. A decreased secretion of IL‐8 challenged by mitophagy inhibitor Mdivi‐1 with an NF‐κB luciferase system was confirmed. Importantly, secretory senescent epithelial cells promoted the breast cancer (MCF‐7) proliferation while decreased the survival of normal epithelial cells demonstrated by co‐culture system, which was remarkably alleviated by ginsenoside Rh2 treatment. These data included ginsenoside Rh2 regulated ROS and mitochondrial autophagy, which were in large part attributed to secretory phenotype of senescent breast epithelial cells induced by doxorubicin. These findings also suggested that ginsenoside Rh2 is a potential treatment candidate for the attenuation of aging related disease.     

Antidepressant‐like effects of 20(S)‐protopanaxadiol in a mouse model of chronic social defeat stress and the related mechanisms

20(S)‐Protopanaxadiol (PPD) is a basic aglycone of the dammarane triterpenoid saponins and exerts antidepressant‐like effects on behaviour in the forced swimming test (FST) and tail suspension test (TST) and in rat olfactory bulbectomy depression models. However, the antidepressant effects of PPD have not been studied thoroughly. The objective of the present study was first to investigate the effect of PPD on depression behaviours induced by chronic social defeat stress (CSDS) in mice. The results showed that CSDS was effective in producing depression‐like behaviours in mice, as indicated by decreased responses in the social interaction test, sucrose preference test, TST, and FST, and that this effect was accompanied by noticeable alterations in the levels of oxidative markers (superoxide dismutase, catalase, and lipid peroxidation) and monoamines (5‐HT and NE) in the hippocampus and serum corticosterone levels. Additionally, western blot analysis revealed that CSDS exposure significantly downregulated BDNF, p‐TrkB/TrkB, p‐Akt/Akt, and p‐mTOR/mTOR protein expression in the hippocampus. Remarkably, chronic PPD treatment significantly ameliorated these behavioral and biochemical alterations associated withCSDS‐induced depression. Our results suggest that PPD exerts antidepressant‐like effects in mice with CSDS‐induced depression and that this effect may be mediated by the normalization of neurotransmitter and corticosterone levels and the alleviation of oxidative stress, as well as the enhancement of the PI3K/Akt/mTOR‐mediated BDNF/TrkB pathway.     

对药酸枣仁-合欢花对抑郁模型大鼠行为学及皮质ERK-CREB细胞信号转导通路的影响

目的探讨对药酸枣仁-合欢花对抑郁模型大鼠行为学及皮质细胞外信号调节蛋白激酶(ERK)-环磷腺苷反应元件结合蛋白(CREB)细胞信号传导通路的影响。方法将雄性2月龄SD大鼠75只,按随机数字表法分为正常组、模型组、中药组、西药组、PD184161组,每组15只。采用孤养加慢性不可预知性温和应激(CUMS)复制大鼠抑郁模型,于实验前1d及实验第1、2、3周末用旷场实验、糖水消耗实验观察各组大鼠的行为学改变。采用实时荧光定量聚合酶链式反应(Real-Time PCR)法对皮质CREB、BDNF mRNA行定量分析。蛋白质免疫印迹(Western Blot)法测皮质ERK1/2、p-ERK1/2、p-RSK及p-CREB蛋白表达水平。结果与正常组比较,模型组大鼠旷场实验得分、糖水消耗度下降,从第2周末开始有统计学意义(P<0.05,P<0.01)、皮质CREB、BDNF mRNA水平下降(P<0.05,P<0.01)、ERK1/2、p-ERK1/2、p-RSK、p-CREB蛋白表达降低(P<0.05,P<0.01);与模型组比较,中药组、西药组、PD184161组大鼠旷场实验得分、糖水消耗度提高,从第2周末开始有统计学意义(P<0.05,P<0.01),皮质CREB、BDNF mRNA水平上调(P<0.05),ERK、p-ERK、p-RSK、p-CREB蛋白表达增强(P<0.05,P<0.01);与中药组比较,PD184161组大鼠旷场实验得分、糖水消耗度下降,第3周末有统计学意义(P<0.05),皮质CREB、BDNF mRNA水平下降(P<0.05),ERK、p-ERK、p-RSK、p-CREB蛋白表达降低(P<0.05)。结论对药酸枣仁-合欢花能够改善抑郁模型大鼠的抑郁症状,具有抗抑郁功效,其作用机制可能与激活ERK-CREB信号传导通路,增强通路中关键因子的表达有关。     

Effects of Ginsenoside Rg1 on Learning and Memory in a Reward‐directed Instrumental Conditioning Task in Chronic Restraint Stressed Rats

Ginsenoside Rg1 is one of the major active ingredients of Panax ginseng and has showed notable improving learning and memory effects in several behavioral tasks, such as water maze, shuttle‐box, and step‐through, based on avoidance. However, there was no report about the role of Rg1 on the performance of reward‐directed instrumental conditioning, which could reflect the adaptive capacity to ever‐changing environments. Thus, in this study, the reward devaluation test and conditional visual discrimination task were conducted to study the ameliorating effects of Rg1 on cognitive deficits, especially the loss of adaptation capacity in chronic restraint stress (CRS) rat model. Our results showed that rat subjected to CRS became insensitive to the changes in outcome value, and it significantly harmed the rat's performance in conditional visual discrimination task. Moreover, the levels of BDNF, TrkB, and Erk phosphorylation were decreased in the prefrontal cortex of CRS rats. However, these changes were effectively reversed by Rg1 (5 and 10 mg/kg, i.p.). Therefore, it demonstrated that Rg1 has a good ability to improve learning and memory and also ameliorate impaired adaptive capacity induced by CRS. This amelioration effect of Rg1 might be mediated partially by BDNF/TrkB/Erk pathway in prefrontal cortex. Copyright © 2016 John Wiley & Sons, Ltd.     

槐定碱对大鼠学习记忆的影响及其ERK信号转导机制

目的 观察槐定碱( sophoridine,SRI)对大鼠学习记忆和海马神经元p- ERK1/2表达的影响.方法 成年SD大鼠24只随机分为生理盐水对照组、槐定碱组、PD98059+槐定碱组,腹腔注射大剂量槐定碱(47.83mg/kg)后,观察各组大鼠行为学改变,Morris水迷宫检测大鼠的学习和记忆,免疫组化测定海马组织内p- ERK1/2阳性细胞数.结果 与生理盐水对照组相比,槐定碱组大鼠逃避潜伏期明显延长,穿越平台次数明显减少(P＜0.05);海马组织内p - ERK1/2阳性细胞数明显增加(P＜0.05).经PD98059干预后,槐定碱致痫大鼠逃避潜伏期显著减小,穿越平台次数明显增多(P＜0.05);海马组织内p- ERK1/2阳性细胞数明显降低(P＜0.05).结论 槐定碱可能通过ERK信号通路损伤海马神经元,从而影响大鼠的空间学习记忆能力.     

Exploring the Effect of Ginsenoside Rh1 in a Sleep Deprivation‐Induced Mouse Memory Impairment Model

Panax ginseng C.A. Meyer (Araliaceae) has been used in traditional Chinese medicine for enhancing cognition for thousands of years. Ginsenoside Rh1, a constituent of ginseng root, as with other constituents, has memory‐improving effects in normal mice and scopolamine‐induced amnesic mice. Sleep deprivation (SD) is associated with memory impairment through induction of oxidative stress. The present study investigated the effect of Rh1 against SD‐induced cognitive impairment and attempted to define the possible mechanisms involved. Ginsenoside Rh1 (20 μmol/kg; 40 μmol/kg) and modafinil (0.42 g/kg) were administered to the mice intraperitoneally for 23 days. After 14‐day SD, locomotor activity was examined using the open field test, and the object location recognition and Morris water maze tests were used to evaluate cognitive ability. The cortex and hippocampus were then dissected and homogenized, and levels and activities of antioxidant defense biomarkers were evaluated to determine the level of oxidative stress. The results revealed that Rh1 prevented cognitive impairment induced by SD, and its ability to reduce oxidative stress in cortex and hippocampus may contribute to the mechanism of action. Copyright © 2017 John Wiley & Sons, Ltd.     

The Anti‐Angiogenic Activities of Glycyrrhizic Acid in Tumor Progression

Glycyrrhizic acid (GA) is the bioactive compound of licorice and has been used as a herbal medicine because of its anti‐viral, anti‐cancer, and anti‐inflammatory properties. This study was designed to investigate the effects of GA on tumor growth, angiogenesis, and the mechanisms underlying the anti‐angiogenic activities of GA. We observed that GA inhibited tumor growth and angiogenesis in mice. GA decreased angiogenic activities, such as the migration, invasion, and tube formation of endothelial cells. We also demonstrated that GA reduced the production of reactive oxygen species and activation of ERK in endothelial cells. Our findings suggest that GA is a promising anti‐angiogenic therapeutic agent that targets the ERK pathway. Considering that angiogenesis is highly stimulated in the majority of cancers, GA could offer a potent therapeutic agent for cancer. Copyright © 2012 John Wiley & Sons, Ltd.