Protective effects of icariin on learning and memory deficits induced by aluminium in rats

This study examined the protective effects of icariin （ICA） on the learning and memory deficits in Aluminium （Al） -treated rats and potential mechanisms. The screened, qualified rats were treated with 1. 6 g/L AlCl3 in drinking water for 8 months, and the ability of spatial learning and memory was tested by Morris water maze. Aluminium （Al） administration significantly increased the mean escape latency searching distance in place navigation test, and decreased the searching time in the quadrant once the platform was in space probe test and adjusted searching distance in space probe test, indicative of brain spatial learning and memory deficits. ICA treatment （60, 120 mg/kg, i. g 3 month） significantly protected against Al-induced spatial learning and memory deficits, as evidenced by decreased escape latency and searching distance, and by increased the searching time in the quadrant once the platform was adjusted via searching distance compared with the Al alone group. To examine the mechanisms of the protection, the activities of superoxide dismuase （SOD） and the contents of maloidaldehyde （MDA） in hippocampus were assayed by commercial kits, and the level of Aβ1-40 in hippocampus was examined by immunohistochemistry （IHC）, respectively. ICA treatment significantly increased the activities of SOD, decreased the content of MDA and the level of Aβ1-40 in hippocampus in a dose - dependent manner. In summary, this study demonstrates that ICA is effective in improving the ability of spatial learning and memory of Al-intoxicated rats.     

Protective effects of xanthoceraside on learning and memory impairment induced by Aβ25–35 in mice

This study examined the effects of xanthoceraside (1) on learning and memory impairment induced in mice by intracerebroventricular injection of aggregated peptide β-amyloid 25–35 (Aβ_25–35). Learning and memory functions in mice were examined using step-through, Y-maze and water maze tests. Administration of 1 reduced the number of errors and prolonged latency in the step-through test in mice impaired by Aβ_25–35. Likewise, latency to find the terminal platform was decreased and the number of right reflects was increased in the water maze test, and the percentage of alternation behaviors in the Y-maze test was increased. Biochemical studies showed that decreased activities of superoxide dismutase, glutathione peroxidase, and acetylcholinesterase, and increased content of malondialdehyde in mice impaired by Aβ_25–35 were significantly ameliorated by administration of 1. The present results suggest that 1 may provide a potential treatment strategy for Alzheimer's disease.     

Novel squamosamide derivative （compound FLZ） attenuates Aβ25-35^- induced toxicity in SH-SY5Y cells

AIM: The aim of the present study was to investigate the protective effect of compound N-[2-(4-hydroxy-phenyl)-ethyl]-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide (compound FLZ), a novel synthetic analogue of nature squamosamide, on Abeta25-35-induced toxicity and its active mechanism in human neuroblastoma SH-SY5Y cells. METHODS: SH-SY5Y cells were pre-incubated with various concentrations of compound FLZ for 30 min and then cultivated with Abeta25-35 (25 micromol/L) for 48 h to induce neurotoxicity. Cell viability, lactate dehydrogenase (LDH) release, and the glutathione (GSH) level were determined by a biochemical analysis. The cell apoptotic ratio and intracellular reactive oxygen species (ROS) level were measured by a flow cytometry analysis. The expression of apoptosis protein (Bcl-2 and Bax) and cytochrome c release were assayed by the Western blot method. RESULTS: The pretreatment of SH-SY5Y cells with FLZ (1 and 10 micromol/L) markedly increased cell viability and decreased LDH release and morphological injury. Also, FLZ attenuated the Abeta25-35-induced apoptotic cell ratio, regulated the apoptosis protein (Bcl-2 and Bax) expression, and decreased the cytochrome c release from mitochondria. FLZ also significantly inhibited the generation of ROS and the depletion of GSH induced by Abeta25-35 in SH-SY5Y cells. CONCLUSION: FLZ has protective action against Abeta25-35-induced toxicity in SH-SY5Y cells, which might be mediated through its antioxidant property.     

Protective effects of baicalin on oxygen/glucose deprivation - and NMDA -induced injuries in rat hippocampal slices

Baicalin is a flavonoid derivative from Scutellaria baicalensis Georgi with various pharmacological effects. Recently, the neuroprotective effect of baicalin has been reported. To confirm this effect and explore the possible mechanism, we investigated the protective effect of baicalin on ischemic-like or excitotoxic injury and the activation of protein kinase C （ （PKC（） in rat hippocampal slices. In vitro ischemic-like injury was induced by oxygen/glucose deprivation （OGD） and the excitotoxic injury by N - methyl - D - aspartate （NMDA）. The viability and swelling of the slices were detected by TTC staining and image analysis of light transmittance （LT）, respectively,     

Effects of Capsule Yi -Zhi on learning and memory disorder and beta-amyloid peptide induced neurotoxicity in rats

AIM To investigate the effects of Capsule Yi-Zhi (CYZ) on learning and memory disorder and beta-amyloid protein induced neurotoxieity in rats. Methods Various doses of CYZ were administered to Sprague-Dawley (SD) rats for 8 days, twice a day. Then scopolamine hydrobromide (Sco) intraperitoneal injection was performed on each rat and the     

Experimental study of icariin on improvement of the learning and memory in AD rats induced by Aβ25 -35

Aim： To examine the protective effects of icariin （ICA） on the learning and memory deficits of Alzheimer＇s disease （AD） model rats induced by Aβ25 -35 and its potential mechanisms. Methods： The rats were randomized and divided into six groups of sixteen animals each. They were sham, Normal saline, model, ICA 30 mg. kg - 1, ICA 60 mg. kg - 1 and ICA 120 mg. kg -1. Wistar rats were microinjected beta-amyloid peptide segment 25 -35 （AI325 -35） into hippocampus. ICA （30 - 120 mg.kg - 1, ig. ） had been administered for fourteen days. The ability of spatial learning and memory was tested by Morris water maze ; Brain tissues were made into paraffin section of 6μm thickness and were stained with Hematoxylin- eosin and Congo red to observe with optical microscope.     

Effects of presenilins and β-amyloid precursor protein on delayed rectifier potassium channels in cultured rat hippocampal neurons1

AIM: To study the effects of presenilin-1 (PS-1), presenilin-2 (PS-2), and amyloid beta-protein precursor (APP695) on delayed rectifier potassium channels (IK) in the cultured rat hippocampal neurons. METHODS: PS-1, PS-2, and APP695 were transfected into the cultured rat hippocampal neurons by transient transfection techniques. The IK current was observed by the whole cell patch-clamp techniques. RESULTS: IK was increased in cultured rat hippocampal neurons, after transient transfection of PS-1, PS-2, and APP695. IK amplitudes and densities were significantly increased from (1689 +/- 412) pA, (48 +/- 18) pA/pF (mock cells, GFP alone, n=17) to (5565 +/- 1403) pA, (252 +/- 107) pA/pF (PS-1/GFP, n=22, P<0.01), (3804 +/- 1651) pA, (120 +/- 58) pA/pF (PS-2/GFP, n=16, P<0.01), and (4978 +/- 904) pA, (218 +/- 70) pA/pF (APP695, n=22, P<0.01). But PS-1, PS-2, and APP695 did not alter the activation curve of IK (P>0.05). CONCLUSION: Overexpression of PS-1, PS-2, and APP695 increased IK in the cultured rat hippocampal neurons. The upregulation of IK may be related to neuronal apoptosis after PS-1, PS-2, and APP695 were transfected.     

Effects of tanshinone on neuropathological changes induced by amyloid β-peptide1-40 injection in rat hippocampus

AIM: To investigate the effect of tanshinone (Tan) on the neuropathological changes induced by amyloid beta-peptide1-40 (Abeta1-40) injection in hippocampus in rats. METHODS: Abeta1-40 10 microg was injected bilaterally into the dorsal blade of the dentate gyrus in the hippocampus. The level of acetylcholinesterase (AChE) in hippocampus was evaluated by histochemistry. The expressions of neuronal nitric oxide synthase (nNOS) and inducible form of NOS (iNOS) were detected by immunohistochemistry and Western blot. Abeta1-40-injected rats were treated ig with Tan, the major active ingredient from Salvia miltiorrhiza of Chinese herb extract. RESULTS: The level of AChE positive fibers of each subfield in Abeta1-40-injected hippocampus decreased significantly compared with those of control (P<0.01). The expression of nNOS was down-regulated whereas the iNOS was up-regulated. After treatment with Tan (50 mg/kg, ig), the changes mentioned above were significantly improved. Moreover, the correlation analysis revealed a significant negative correlation between the area percentage of AChE positive fibers and the number of iNOS positive neural cells in CA1, CA2 to CA3 (CA2-3), and dentate gyrus (DG) subfields (P<0.01). CONCLUSION: Tan can protect the neuropathological changes induced by Abeta1-40 injection in hippocampus.     

Protective effects of compound FLZ,a novel synthetic analogue of squamosamide,on β-amyloid-induced rat brain mitochondrial dysfunction in vitro

Aim： The aim of the present study was to assess the effects of N-[2-（4-hydroxyphenyl）ethyl]-2-（2,5-dimethoxyphenyl）-3-（3- methoxy-4-hydroxyphenyl） acrylamide （compound FLZ）, a novel synthetic analogue of squamosamide, on the dysfunction of rat brain mitochondria induced by Aβ25-35 in vitro. Methods： Isolated rat brain mitochondria were incubated with aged Aβ25-35 for 30 rain in the presence and absence of FLZ （1-100 μmol/L）. The activities of.key mitochondrial enzymes, the production of hydrogen peroxide （H2O2） and superoxide anion （O2^-）, and the levels of glutathione （GSH） in mitochondria were examined. Mitochondrial swelling and the release of cytochrome c from mitochondria were assessed by biochemical and Western blot methods, respectively. Results： Incubation of mitochondria with aged Aβ25-35 inhibited the activities of α-ketoglutarate dehydrogenase （α-KGDH）, pyruvate dehydrogenase （PDH） and respiratory chain complex IV. It also resulted in increased H2O2 and O2^- production, and decreased the GSH level in mitochondria. Furthermore, it induced mitochondrial swelling and cytochrome c release from the mitochondria. The addition of FLZ （100 μmol/L） prior to treatment with Aβ25-35 significantly prevented these toxic effects of Aβ25-35 on the mitochondria. Conclusion： FLZ has a protective effect against Aβ25-35-induced mitochondrial dysfunction in vitro.     

Liquiritigenin inhibits Aβ25-35-induced neurotoxicity and secretion of Aβ1-40 in rat hippocampal neurons

Aim： To examine whether liquiritigenin, a newly found agonist of selective estrogen receptor-β, has neuroprotective activity against β-amyloid peptide （Aβ） in rat hippocampal neurons.
Methods： Primary cultures of rat hippocampal neurons were pretreated with liquiritigenin （0.02, 0.2, and 2 pmol/L） prior to Aβ25-35 exposure. Following treatment, viability of the cells was measured by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide analysis and by a lactate dehydrogenase activity-based cytotoxicity assay. Intracellular Ca^2＋ concentration （[Ca^2＋]i） and levels of reactive oxygen species （ROS）, as well as apoptotic rates, were determined. Our studies were extended in tests of whether liquiritigenin treatment could inhibit the secretion of Aβ1-40 as measured using an ELISA method. In order to analyze which genes may be involved, we used a microarray assay to compare gene expression patterns. Finally, the levels of specific proteins related to neurotrophy and neurodenegeration were detected by Western blotting.
Results： Pretreated neurons with liquiritigenin in the presence of Aβ25-35 increased cell viability in a concentration-dependent manner. Liquiritigenin treatment also attenuated Aβ25-35-induced increases in [Ca^2＋]i and ROS level and decreased the apoptotic rate of neurons. Some genes, including B-cell lymphoma/leukemia-2 （Bcl-2）, neurotrophin 3 （Ntf-3） and amyloid [3 （A4） precursor protein-binding, family B, member 1 （Apbb-1） were regulated by liquiritigenin; similar results were shown at the protein level by Western blotting.
Conclusion： Our results demonstrate that liquiritigenin exhibits neuroprotective effects against Aβ25-35-induced neurotoxicity and that it can decrease the secretion of Aβ1-40. Therefore, liquiritigenin may be useful for further study as a prodrug for treatment of Alzheimer＇s disease.     

Effects of baicalein on beta-amyloid peptide-(25-35)-induced amnesia in mice

Baicalein may act on the benzodiazepine binding sites to exert an anxiolytic-like effect in mice. Since many benzodiazepine drugs have amnesic side-effect and baicalein can protect cultured cortical neurons from beta-amyloid peptide-(25-35)-induced toxicity, this study examined the amnesic effect of baicalein and its effects on beta-amyloid peptide-(25-35) (3 nmol/mouse, i.c.v.)-induced amnesia in mice. Using the step-through passive avoidance test, the results showed that baicalein (10-100 mg/kg, i.p.), unlike the benzodiazepine drug chlordiazepoxide (10 mg/kg, i.p.), had no significant amnesic effect. Baicalein (10-50 mg/kg, i.p.) also had no facilitating effect on the learning and memory. However, one dosage pretreatment, but not post-treatment, of baicalein (5 or 10 mg/kg, i.p.) attenuated beta-amyloid peptide-(25-35)-induced amnesia. Interestingly, post-treatment for 7 or 13 days of baicalein (10-15 mg/kg/day, i.p.), like melatonin (10 mg/kg/day, i.p.), also attenuated beta-amyloid peptide-(25-35)-induced amnesia. Therefore, this study demonstrated that baicalein has protective effect on beta-amyloid peptide-(25-35)-induced amnesia.     

The effects of acute and repeated oroxylin A treatments on Abeta(25-35)-induced memory impairment in mice

Oroxylin A is a flavonoid that is found in the roots of Scutellaria baicalensis Georgi. The aim of this study was to characterize the effects of oroxylin A on the memory impairments and pathological changes induced by Aβ_25-35 peptide in mice. The ameliorating effect of oroxylin A on memory impairment was investigated using passive avoidance and Y-maze tasks and pathological changes were identified by immunostaining and western blotting. Aβ_25-35 peptide (5 nmol) was administered by intracerebroventricular injection. In the acute treatment study, a single dose of oroxylin A (5 mg/kg, p.o.) treated 1 h before behavioral tests was found to significantly reverse Aβ_25-35-induced cognitive impairments based on passive avoidance and Y-maze task findings (P < 0.05). Moreover, these acute effects of oroxylin A were blocked by diazepam (1 mg/kg, i.p.), a GABA_A/benzodiazepine binding site agonist (P < 0.05). On the other hand, our subchronic studies revealed that oroxylin A (1 or 5 mg/kg/day, p.o.) for 7 days ameliorated the memory impairment induced by Aβ_25-35 peptide. Moreover, Aβ_25-35-induced increases in GFAP (an astroglia marker) and OX-42 (a microglia marker), and increases in iNOS positive cells in the hippocampus were found to be attenuated by subchronic oroxylin A (1 or 5 mg/kg/day, i.p., P < 0.05). In addition, reductions in the immunoreactivity and protein level of ChAT (a cholinergic neuronal cell marker) in the CA3 hippocampal area induced by Aβ_25-35 peptide were also attenuated by oroxylin A. Furthermore, lipid peroxidation induced by Aβ_25-35 was also reduced by oroxylin A. These results suggest that the amelioration of Aβ_25-35 peptide-induced memory impairment by oroxylin A is mediated via the GABAergic neurotransmitter system after a single administration, or by reductions in Aβ_25-35 peptide-induced astrocyte and microglia activations, iNOS expression, lipid peroxidation, and increased cholinergic neurotransmission after subchronic administration.     

人参皂苷Rg1对β—淀粉样肽（25—35）侧脑室注射所致小鼠学习记忆障碍的改善

AIM: To study the effect of ginsenoside Rg1 on the learning and memory impairment in mice induced by aggregated beta-AP(25-35). METHODS: Mice were administered Rg1(5, 10 mg.kg-1, i.p.) for 10 d and control mice received daily i.p. injections of saline after the intracerebroventricular injection of aggregated beta-AP(25-35). After the final treatment, passive avoidance and performance in the Morris water maze (MWM) were assessed. and the activity of cortical and hippocampal ChAT and AchE were detected after the final behavior test. RESULTS: Ginsenoside Rg1 (5, 10 mg.kg-1, i.p.) significantly ameliorated the learning and memory impairment induced by beta-AP(25-35). Rg1 (5, 10 mg.kg-1) decreased the latencies and swim distances of mice to reach a hidden platform and improved the corresponding changes in search strategies occurred in the Morris water maze, and Rg1 (10 mg.kg-1, i.p.), increased step-through latencies also. Biochemical analysis showed that Rg1 (5, 10 mg.kg-1, i.p.), prevented the cortical and hippocampal ChAT activity decline induced by beta-AP(25-35), and showed inhibition of the activity of AchE, although beta-AP(25-35) showed no effect on the cortical and hippocampal AchE activity. CONCLUSION: These data showed that ginsenoside Rg1 significantly improved the learning and memory impairment induced by beta-AP(25-35), and this effect could be attributed to its inhibition of AchE and increase of ChAT activity.     

Soluble beta-amyloid[25-35] reversibly impairs hippocampal synaptic plasticity and spatial learning

Beta-amyloid is a peptide that appears to be responsible for cognitive impairments in patients with Alzheimer's disease. Recent research shows that soluble oligomers of beta-amyloid affect synaptic activity and learning, well before any amyloid has aggregated into plaques. Here we show that injection of 3x10 nmol amyloid [25-35] i.c.v. transiently impairs learning of a radial arm maze and the induction of hippocampal long-term potentiation. Furthermore, hippocampal field potentials had been recorded over a period of 21 days and were found to be reduced from day 9 to day 15 (P<0.001), after which the reduction had reversed to baseline. In the spatial 8-arm learning task, animals had to learn which 3 out of 8 arms had been baited. A significant impairment of working and long-term memory was observed at day 12-20 (P<0.001), but not at days 3-11 or 20-28. Long-term potentiation induction in the hippocampus area CA1 was also impaired at day 12-20 (P<0.001), but not at other days. A scrambled peptide sequence version of amyloid did not have any effect. These results emphasise that soluble amyloid fragments already have detrimental effects on brain function well before aggregation occurs. They also show that these effects are reversible, and therefore most likely do not involve neuronal death. The neurodegeneration seen in Alzheimer's disease brains is most likely a downstream effect, linked to processes such as immune response activation and free radical production. These results suggest that treatment at very early stages of Alzheimer's disease could prevent later irreversible neuronal degeneration.     

Growth hormone releaser attenuates beta-amyloid (1 - 42)-induced memory impairment in mice

Accumulating evidence indicates that growth hormone (GH) might be effective at preventing the development of Alzheimer's disease. However, exogenous GH treatment has exhibited side effects for clinical application; thus supplementation with amino acids to promote the release of GH could be a possible alternative treatment. In this study, mice that were fed with a diet of GH-releasing supplements had significantly attenuated memory impairments and hippocampal changes in the acetylcholinesterase activity and acetylcholine level induced by amyloid beta protein (Abeta) (1 - 42). Our results suggest that the use of GH-releasing supplement exerts beneficial effects on the memory impairment induced by Abeta (1 - 42).     

淫羊藿苷对淀粉样β蛋白片段25-35所致大鼠学习记忆障碍的改善作用

目的观察淫羊藿苷对淀粉样β蛋白片段25-35(Aβ25-35)所致阿尔茨海默病(AD)模型大鼠学习记忆能力的保护作用,并探讨其可能的作用机制。方法Wistar雄性大鼠,右侧海马内注射Aβ25-3510μg制备AD模型,次日起淫羊藿苷30,60和120mg.kg-1灌胃给药,连续14d,d15～19Morris水迷宫检测大鼠空间辨别学习记忆能力;d20检测海马组织中谷胱甘肽过氧化物酶(GSH-PX)、超氧化物歧化酶(SOD)及一氧化氮合酶(NOS)的活性,免疫组化法检测海马内乙酰胆碱酯酶(AChE)和胆碱乙酰转移酶(ChAT)的表达。结果与模型对照组比较,淫羊藿苷给药14d明显改善大鼠学习记忆能力;海马组织中SOD和GSH-PX活性升高,NOS活性降低;海马内AChE及ChAT的表达增加。结论淫羊藿苷可以改善Aβ25-35海马内注射所致AD模型大鼠的学习记忆能力,其作用可能与其增加AChE和ChAT表达,增强SOD和GSH-PX等自由基清除酶活性,降低NOS活性,减少NO释放等多种机制,促进胆碱能递质系统功能的恢复有关。     

Protective effects of bilobalide on amyloid beta-peptide 25-35-induced PC12 cell cytotoxicity

AIM: To study the effect of bilobalide, a terpene extracted from the leaves of Ginkgo biloba, on beta-amyloid peptide fragment 25-35 (A beta 25-35)-induced PC12 cell cytotoxicity. METHODS: 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay were used to measure the viability of PC12 cells. Thiobarbituric acid-reactive substances were measured to determine lipid peroxidation of cells. Antioxidant enzymes in PC12 cells were detected. RESULTS: Treatment of PC12 cells with A beta 25-35 (100 mumol.L-1) for 24 h caused a great decrease in cell viability (P < 0.01 compared with control). Bilobalide 25-100 mumol.L-1 dose-dependently attenuated the cytotoxic effect of A beta 25-35. Bilobalide also inhibited A beta 25-35 (100 mumol.L-1)-induced elevation of lipid peroxidation and decline of antioxidant enzyme activities. CONCLUSION: Bilobalide protected PC12 cells from A beta 25-35-induced cytotoxicity.     

白果内酯对抗淀粉样β-肽25-35所致PC12细胞毒作用(英文)

目的:观察白果内酯对β-淀粉样蛋白片段25-35(Aβ25-35)所致PC12细胞毒性的影响。方法:用噻唑兰(MTF)及乳酸脱氢酶法检测PC12细胞的存活率;硫代巴比妥酸法测定细胞脂质过氧化;并同时检测了细胞内抗氧化酶活性。结果:白果内酯(25-100)μmol·L~(-1)剂量依赖性地抑制Aβ25-35(100 μmol·L~(-1))引起的细胞存活率下降,脂质过氧化及抗氧化酶活性下降。结论:白果内酯具有对抗Aβ25-35引起的PC12细胞毒性的作用。     

Noopept improves the spatial memory and stimulates prefibrillar beta-amyloid(25-35) antibody production in mice

The effects of the novel proline-containing nootropic and neuroprotective dipeptide noopept (GVS-111, N-phenylacetyl-L-prolylglycine ethyl ester) were studied on NMRI mice upon olfactory bulbectomy, which had been previously shown to imitate the main morphological and biochemical signs of Alzheimer's disease (AD). The spatial memory was assessed using the Morris (water maze) test; the immunological status was characterized by ELISA with antibodies to prefibrillar beta-amyloid(25-35), S100b protein, and protofilaments of equine lysozyme, which are the molecular factors involved in the pathogenesis of AD. The control (sham-operated) animals during the Morris test preferred a sector where the safety platform was placed during the learning session. Bulbectomized animals treated with saline failed to recognize this sector, while bulbectomized animals treated with noopept (0.01 mg/kg for 21 days) restored this predominance, thus demonstrating the improvement of the spatial memory. These animals also demonstrated an increase in the level of antibodies to beta-amyloid(25-35)--the effect, which was more pronounced in the sham-operated than in bulbectomized mice. The latter demonstrated a profound decrease of immunological reactivity in a large number of tests. Noopept, stimulating the production of antibodies to beta-amyloid(25-35), can attenuate the well-known neurotoxic effects of beta-amyloid. The obtained data on the mnemotropic and immunostimulant effects noopept are indicative of good prospects for the clinical usage of this drug in the therapy of patients with neurodegenerative diseases.