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One of pathological features of Alzheimer's disease (AD) is extracelluar aggregation of amyloid-β protein (Aβ) forming senile plaques. Investigation on inhibition of Aβ aggregation can be crucial for designing effective drugs against AD. Previous studies have demonstrated that the deamidation at Asn27, a type of post translation modification, significantly prevented the polymerization of Aβ monomers. But the underlying mechanism is still unclear. Therefore, we investigated the possible effect of Asn27 deamidation on structure and aggregation of Aβ42 monomer using molecular dynamics simulation. The results showed that the deamidation of Asn27 can directly disrupt the salt bridge formed between D23 and K28, and effectively decrease the content of β-sheet that is important for aggregation of Aβ. Moreover, the inability at C-terminal region (CTR) and N-terminal region (NTR) to form antiparallel β-sheets further weakens the intra-peptide interaction of Aβ42 monomer. These changes caused by Asn27 deamidation lead to the decline of the aggregated trend of Aβ42 monomer, which is consistent with the experimental observation. According to these results, the salt bridge formed between D23 and K28 plays an important role in promoting the polymerization process between Aβ42 monomers, and disrupting this interaction may be a potential direction for further designing drugs to inhibit aggregation of Aβ42. In summary, this study shows a potential affected site that can efficiently inhibit aggregation of Aβ42.
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Objective To observe the effect of electroacupuncture at " Baihui"," Shenshu" and " Taixi" points on learning and memory,the expression of Aβ and insulin degrading enzyme(IDE) in the brain of SAMP8 mice.Methods Eight-month-old SAMR1 and SAMP8 mice were treated with electroacupuncture at " Baihui"," Shenshu" and "Taixi" points for eight consecutive weeks.The distribution and expression of Aβ and IDE in the brain prefrontal cortex of mouse were observed using immunohistochemistry and Western blot.Learning and memory function was assayed by Morris water maze(MWM).Results Compared with the normal control group,the brain prefrontal cortex of SAMP8 mice showed increased Aβ levels ((179.02± 15.11) ％),decreased IDE protein expression ((51.35 ± 14.94) ％).MWM showed the escape latency in SAMP8 mice was significantly longer than that in the control group (P＜0.05).Compared with the model group,Aβ levels in SAMP8 mice were markedly decreased in electroacupuncture group((119.72±9.21)％) and memantine-treated group ((116.84 ± 12.09) ％).IDE protein levels were increased by ((92.06 ± 8.05) ％) and ((83.84± 15.28) ％) after treatment with electroacupuncture and memantine relative to model group.MWM showed the escape latency was significantly shorter in SAMP8 mice treated with electroacupuncture and memantine than that in the model group(P＜0.05).Conclusion Electroacupuncture at " Baihui"," Shenshu" and "Taixi" points can inhibit Aβ levels,increase the expression of IDE and improve the learning and memory function of SAMP8 mice.
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Aim To investigate the neuroprotective effects of osthole(Ost)on the primary cultured cortical neurons transfected with APP595/596 gene and its underlying mechanism.Methods Neonatal mouse cortical neurons were transfected with APP595/596 gene to establish AD cell models for the further study.Then,the cell viability was detected by CCK-8 assay,and the leakage of lactate dehydrogenase(LDH)was assayed by LDH kit to evaluate the injury degree.Transferase-mediated nick end labeling(TUNEL)was used to evaluate the cell apoptosis.The expression of β-amyloid peptide(Aβ)and β-site APP cleaving enzyme 1(BACE1)was measured by immunofluorescence,while the miRNA-107 was measured by RT-PCR.Results Compared to model group,Ost could significantly improve the neurons viability,decrease the LDH release and prevent the apoptosis.Ost also inhibited the expression of Aβ and BACE1 at protein level,while enhanced the expression of miRNA-107 at gene level.Conclusion Ost plays a neuroprotective role in neurons transfected with APP595/596 gene in part through up-regulating miRNA-107.
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OBJECTIVE To observe the effect of baicalin on Aβ25-35 induced learning and memory deficits and changes in autophagy-related genes in mice so as to explore the related mechanisms of Alzheimer disease (AD) treatment . METHODS C57 mice were administered with 3μL Aβ25-35 3 mmol·L-1 by intracerebroventricular injection to establish an AD model. Baicalin was given by intracerebroventricular injection at the dose of 25, 50 and 100 mg · kg-1 for 15 d, respectively. The total distance and the central grid residence time were measured in the open-field test. The escape latency and the time to reach the platform were monitored in the Morris water maze trial. The autophagic vacuoles in the hippocampus of the mice were observed by transmission electron microscopy before the protein expressions of microtu?bule-associated protein 1 light chain 3 (LC3) and Beclin1 in brain tissue were analyzed by Western blot?ting assay. RESULTS Intracerebroventricular injection of Aβ25-35 could reduce the total distance from (3984±321)cm to (2790±306)cm and extend central grid residence time from (3.6±1.2)s to (8.8±2.9)s in the open-field test. The escape latency of water maze also increased from (22.0 ± 1.9)s to (38.8 ± 2.2)s. Autophagic vacuoles or late autophagic vacuoles and increased Beclin1 and LC3 and protein level were observed in the hippocampus after Aβ25-35 injection. Intraperitoneal injection of Baicalin 50 and 100 mg · kg-1 for fifteen consecutive days extended the total distance in open-field test to (3705 ± 337)cm and (3968 ± 448)cm, respectively, while the central grid residence time was reduced to (5.6 ± 1.8)s and (3.9±1.5)s, respectively. The total time taken to reach the platform in water maze test was reduced to (28.6± 1.9)s, (22.9 ± 1.7)s. Mitochondrial swelling, vacuolar membrane structure or autophagic vacuoles were visible in the hippocampus. LC3 and Beclin1 protein expression was significantly up-regulated(P<0.01). CONCLUSION Baicalin shows protective effect against Aβ25-35 induced learning and memory deficits, and this effect may be related to the activation of autophagy in the mouse hippocampus.
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This study was designed to investigate the effect of gastrodin (GAS) against β-amyloid plaques in 5×FAD Alzheimer's disease (AD) transgenic mice, and utilize 117 cell model (over-expression of Aβ and β-secretase) to explore the underlying mechanism. 5×FAD mice model were randomly divided into three groups, including GAS-high dose group (GAS-H, 200 mg·kg-1·d-1), GAS-middle dose group (GAS-M, 100 mg·kg-1·d-1) and GAS-low dose group (GAS-L, 50 mg·kg-1·d-1). Meanwhile, the wild type mice were used in the control group. After being treated with GAS for three months, 5×FAD mice were evaluated by Morris water maze for the learning and memory ability and by ELISA for Aβ in the cerebral homogenate. Then, Aβplaques in the hippocampus and cortex of 5×FAD mice were observed and analyzed with immunohistochemical staining. The cell apoptosis rate and the cell viability were determined in vitro, after the cells were treated with different concentrations of GAS (10, 25, 50 and 100 μmol·L-1). Furthermore, Intracelluar/extracelluar Aβ were determined by ELISA. Effects of GAS on BACE (β-secretase site APP cleaving enzyme) mRNA and protein expression were analyzed in 117 cell models by Q-PCR and Western blotting. The results suggest that GAS is able to restore the learning and memory capacity of 5×FAD mice, and reduce Aβ in the cerebral homogenate and Aβ plaques in the brain. Compared with the untreated transgenic positive group, A β plaques were declined in hippocampus and cortex of GAS-H group by 93.28% and 88.88%, and A β was reduced in the cerebral homogenate by 55.74%. In vitro study suggests a dose-dependent effect of GAS in reducing Aβ in 117 cell models. When the cells were treated with 100 μmol·L-1 GAS, extracelluar Aβ and intracellular Aβ of 117 cells were reduced by 63.1% and 49.1%. BACE expression was largely suppressed in mRNA by 32.9% (P-1 GAS, the protein level was declined by 47.9% (Pβ production and accumulation by inhibiting β-secretase.
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Objective To explore the effects of resveratrol on the express of inflammatory factors (IL‐1 ,IL‐6 ,TNF‐α)of hu‐man umbilical vein endothelial cells(HUVEC) induced by Aβ1 -42 .Methods HUVEC were stimulated with Aβ1 -42 5 × 101 μmol/L , last 24 h and administrated with resveratrol 160 ,80 ,40 ,20 μg/L ,HUVEC viability were detected by CCK‐8 ;the concentration of IL‐1 ,IL‐6 and TNF‐α were detected by ELISA .Results Compared with model group ,160 ,80 ,40 ,20 μg/L resveratrol could in‐crease HUVEC survival rate ,reduced HUVEC damage by Aβ1 -42 ,inhibited the concentration of IL‐1 ,IL‐6 and TNF‐α(P<0 .05) . Conclusion Resveratrol over 20 μg/L could reduce the release of IL‐1 ,IL‐6 and TNF‐αof HUVEC inducing by Aβ1 -42 .
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One of the early pathological hallmarks of Alzheimer׳s disease (AD) is the deposition of amyloid-β (Aβ) plaques in the brain. There has been a tremendous interest in the development of Aβ plaques imaging probes for early diagnosis of AD in the past decades. Optical imaging, particularly near-infrared fluorescence (NIRF) imaging, has emerged as a safe, low cost, real-time, and widely available technique, providing an attractive approach for in vivo detection of Aβ plaques among many different imaging techniques. In this review, we provide a brief overview of the state-of-the-art development of NIRF Aβ probes and their in vitro and in vivo applications with special focus on design strategies and optical, binding, and brain-kinetic properties.
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Objective: To determine the effect of polygona-polysaccharose (PP) on learning and memory ability in rats with Alzheimer’s disease (AD). Methods: Forty ifve Sprague-Dawley rats were assigned into 3 groups. Rats in the sham-operated group were injected with normal saline. Rats in the Aβ group were injected with Aβ1-42. Rats in the PP group were injected with 16% PP solution for 45 days consecutively. hTe Morris water maze was used to investigate the ability of learning and memory in the rats. hTe effect of Aβ and PP on the hippocampus cells was observed by HE and Congo red staining of methanol. Results: Rats in the sham-operated group had no obvious morphological change; and morphology of rats in the PP group was basicaly normal. The layer of pyramidal cells in the Aβ group was decreased. hTe cells appeared sparse and irregular and became smaller. Karyopyknosis and vacuolardegeneration cells were also found. More positive staining materials aggradated in the Aβ group compared with the PP group by Congo red staining (P<0.05). Conclusion: Aβ infusion into the hippocampus results in the impairment of the neuronal degeneration in the rats, which shows similar characterizations of AD. PP can reduce the deposition of Aβ in the hippocampus.
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Aim To explore the effects and mecha-nisms of choro-oxime derivatives on spatial learning and memory impairment in Kunming mice and SD rats induced by scopolamine and Aβ1-42 , respectively. Methods 40 Kunming mice were randomly divided into 5 groups: control group, model group, donepezil treatment group, arimoclomol treatment group and TCO-2 treatment group. There were 8 mice in each group. Mice of control group were established by intra-peritoneal injection of saline, and mice of other groups were injected with scopolamine and caused memory im-pairment. Both control group and model group were treated with solvent by intraperitoneal administration;donepezil treatment group received donepezil by intra-gastric administration; arimoclomol treatment group and TCO-2 treatment group were given the correspond-ing drugs by abdominal injection, respectively. The solvent and drugs were given at the same time every morning for 8 days. Spatial learning and memory abili-ty were tested by Morris water maze from the fifth day of the drugs administration. 40 SD rats were divided into 5 groups the same as the dementia model men-tioned above. Mice of control group were established by intracerebroventricular injection of saline, and mice of other groups were injected with insoluble Aβ1-42 to be induced of memory impairment. Solvent and drugs were also delivered as mentioned above. Morris water maze was carried out from the fifth day of the drug de-livery. After that, acetyl cholinesterase activity of hip-pocampus was tested with acetyl cholinesterase reagent kit; the content of Aβ1-42 in hippocampus was meas-ured by ELISA assay kit;the expression of phosphoryl-ated tau proteins was detected by Western Blot. Re-sults In both two dementia models, choro-oxime de-rivatives could improve the spatial learning and memory ability, shorten the escape latency and increase the times of crossing the former platform. Choro-oxime de-rivatives could also inhibit the acetyl cholinesterase ac-tivity in animal brain, decrease the concentration of Aβ1-42 and the expression of phosphorylated tau pro-teins in the dementia rats’ hippocampus. Conclusions Spatial learning and memory deficits induced by sco-polamine and Aβ1-42 could be reversed by choro-oxime derivatives. It may be concerned with enhancement of the cholinergic system functions and reduction of the levels of Aβ1-42 and phosphorylated tau proteins in the brain.
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BACKGROUND: Acanthopanax divaricatus var. albeofructus (ADA) extract has been reported to have anti-oxidant, immunomodulatory, and anti-mutagenic activity. MATERIALS/METHODS: We investigated the effects of ADA extract on two mouse models of Alzheimer's disease (AD); intracerebroventricular injection of beta-amyloid peptide (Abeta) and amyloid precursor protein/presenilin 1 (APP/PS1)-transgenic mice. RESULTS: Intra-gastric administration of ADA stem extract (0.25 g/kg, every 12 hrs started from one day prior to injection of Abeta1-42 until evaluation) effectively blocked Abeta1-42-induced impairment in passive avoidance performance, and Abeta1-42-induced increase in immunoreactivities of glial fibrillary acidic protein and interleukin (IL)-1alpha in the hippocampus. In addition, it alleviated the Abeta1-42-induced decrease in acetylcholine and increase in malondialdehyde levels in the cortex. In APP/PS1-transgenic mice, chronic oral administration of ADA stem extract (0.1 or 0.5 g/kg/day for six months from the age of six to 12 months) resulted in significantly enhanced performance of the novel-object recognition task, and reduced amyloid deposition and IL-1beta in the brain. CONCLUSIONS: The results of this study suggest that ADA stem extract may be useful for prevention and treatment of AD.
Subject(s)
Animals , Mice , Eleutherococcus , Acetylcholine , Administration, Oral , Alzheimer Disease , Amyloid , Brain , Glial Fibrillary Acidic Protein , Hippocampus , Interleukins , Malondialdehyde , Plaque, AmyloidABSTRACT
BACKGROUND: Acanthopanax divaricatus var. albeofructus (ADA) extract has been reported to have anti-oxidant, immunomodulatory, and anti-mutagenic activity. MATERIALS/METHODS: We investigated the effects of ADA extract on two mouse models of Alzheimer's disease (AD); intracerebroventricular injection of beta-amyloid peptide (Abeta) and amyloid precursor protein/presenilin 1 (APP/PS1)-transgenic mice. RESULTS: Intra-gastric administration of ADA stem extract (0.25 g/kg, every 12 hrs started from one day prior to injection of Abeta1-42 until evaluation) effectively blocked Abeta1-42-induced impairment in passive avoidance performance, and Abeta1-42-induced increase in immunoreactivities of glial fibrillary acidic protein and interleukin (IL)-1alpha in the hippocampus. In addition, it alleviated the Abeta1-42-induced decrease in acetylcholine and increase in malondialdehyde levels in the cortex. In APP/PS1-transgenic mice, chronic oral administration of ADA stem extract (0.1 or 0.5 g/kg/day for six months from the age of six to 12 months) resulted in significantly enhanced performance of the novel-object recognition task, and reduced amyloid deposition and IL-1beta in the brain. CONCLUSIONS: The results of this study suggest that ADA stem extract may be useful for prevention and treatment of AD.
Subject(s)
Animals , Mice , Eleutherococcus , Acetylcholine , Administration, Oral , Alzheimer Disease , Amyloid , Brain , Glial Fibrillary Acidic Protein , Hippocampus , Interleukins , Malondialdehyde , Plaque, AmyloidABSTRACT
Excessive accumulation of beta-amyloid peptide (Abeta) is one of the major mechanisms responsible for neuronal death in Alzheimer's disease. Flavonoids, primarily antioxidants, are a group of polyphenolic compounds synthesized in plant cells. The present study aimed to identify flavonoid compounds that could inhibit Abeta-induced neuronal death by examining the effects of various flavonoids on the neurotoxicity of Abeta fragment 25-35 (Abeta25-35) in mouse cortical cultures. Abeta25-35 induced concentration- and exposure-time-dependent neuronal death. Neuronal death induced by 20 microM Abeta25-35 was significantly inhibited by treatment with either Trolox or ascorbic acid. Among 10 flavonoid compounds tested [apigenin, baicalein, catechin, epicatechin, epigallocatechin gallate (EGCG), kaempferol, luteolin, myricetin, quercetin, and rutin], all except apigenin showed strong 1,1-diphenyl-2-pycrylhydrazyl (DPPH) scavenging activity under cell-free conditions. The flavonoid compounds except apigenin at a concentration of 30 microM also significantly inhibited neuronal death induced by 20 microM Abeta25-35 at the end of 24 hours of exposure. Epicatechin, EGCG, luteolin, and myricetin showed more potent and persistent neuroprotective action than did the other compounds. These results demonstrated that oxidative stress was involved in Abeta-induced neuronal death, and antioxidative flavonoid compounds, especially epicatechin, EGCG, luteolin, and myricetin, could inhibit neuronal death. These findings suggest that these four compounds may be developed as neuroprotective agents against Alzheimer's disease.
Subject(s)
Animals , Mice , Alzheimer Disease , Antioxidants , Apigenin , Ascorbic Acid , Catechin , Flavonoids , Luteolin , Neurons , Neuroprotective Agents , Oxidative Stress , Plant Cells , QuercetinABSTRACT
Excessive accumulation of beta-amyloid peptide (Abeta) is one of the major mechanisms responsible for neuronal death in Alzheimer's disease. Flavonoids, primarily antioxidants, are a group of polyphenolic compounds synthesized in plant cells. The present study aimed to identify flavonoid compounds that could inhibit Abeta-induced neuronal death by examining the effects of various flavonoids on the neurotoxicity of Abeta fragment 25-35 (Abeta25-35) in mouse cortical cultures. Abeta25-35 induced concentration- and exposure-time-dependent neuronal death. Neuronal death induced by 20 microM Abeta25-35 was significantly inhibited by treatment with either Trolox or ascorbic acid. Among 10 flavonoid compounds tested [apigenin, baicalein, catechin, epicatechin, epigallocatechin gallate (EGCG), kaempferol, luteolin, myricetin, quercetin, and rutin], all except apigenin showed strong 1,1-diphenyl-2-pycrylhydrazyl (DPPH) scavenging activity under cell-free conditions. The flavonoid compounds except apigenin at a concentration of 30 microM also significantly inhibited neuronal death induced by 20 microM Abeta25-35 at the end of 24 hours of exposure. Epicatechin, EGCG, luteolin, and myricetin showed more potent and persistent neuroprotective action than did the other compounds. These results demonstrated that oxidative stress was involved in Abeta-induced neuronal death, and antioxidative flavonoid compounds, especially epicatechin, EGCG, luteolin, and myricetin, could inhibit neuronal death. These findings suggest that these four compounds may be developed as neuroprotective agents against Alzheimer's disease.
Subject(s)
Animals , Mice , Alzheimer Disease , Antioxidants , Apigenin , Ascorbic Acid , Catechin , Flavonoids , Luteolin , Neurons , Neuroprotective Agents , Oxidative Stress , Plant Cells , QuercetinABSTRACT
This study was aimed to observe different forms of β-amyloid peptide (Aβ) and insulin degrading enzyme (IDE) in the hippocampus and cortex in order to further explore the role of Aβ and IDE on spleen yin deficiency di-abetes-associated cognitive decline (DACD), and the effect of Zi-Bu Pi-Y in method. The rats were randomly divided into five groups, which were the blank control (Cont) group, diabetes (DM) group, spleen yin deficiency (pi) group, spleen yin deficiency diabetes (piDM) group and Zi-Bu Pi-Y in recipe (ZBPYR) group. Soluble and insoluble Aβ in the hippocampus and cortex of rats were extracted by gradient centrifugation, and then measured by ELISA. The ex-pression of IDE was observed by western blot. The results showed that the content of soluble and insoluble Aβ1-42 in the hippocampus and cortex of the DM group and piDM group were higher than the Cont group. The soluble and in-soluble Aβ1-42 content in the hippocampus and cortex of the ZBPYR group were reduced compared with the DM group and the piDM group. The soluble Aβ1-40 in the cortex of the DM group, pi group and piDM group were in-creased compared with the Cont group (P < 0.05). The soluble Aβ1-40 content of the ZBPYR group was decreased compared with the DM group and the piDM group (P < 0.05). The expression of IDE protein was decreased in the hippocampus of the DM group and the piDM group compared with the Cont group (P< 0.05), and the IDE protein level in the hippocampus of the ZBPYR group was increased compared with the DM group and the piDM group (P<0.05). The expression of IDE protein in the cortex of the DM group, pi group and piDM group was lower than the Cont group (P< 0.05). The IDE protein level in the cortex of the ZBPYR group was reduced compared to the DM group (P< 0.05). It was concluded that the increased Aβ1-42 in brain may be a major pathological change of DACD and spleen yin deficiency DACD. The decreased IDE expression may be one of the reasons to induce increasing of Aβ1-42 level. The Zi-Bu Pi-Y in method may decrease the Aβ1-42 content by upregulating IDE protein expression.
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A doença de Alzheimer (DA) é a forma de demência degenerativa esporádica mais comum. Caracteristicamente ocorre expressiva perda neuronal progressiva em locais específicos nas pessoas atingidas. O distúrbio degenerativo progressivo se caracteriza pela perda de sinapses, de neurônios cerebrais e por depósitos de fibrilas de peptídeos de beta-amilóide extraneuronais, constituindo as placas senis e a presença de agregados intraneuronais da proteína tau, formando os emaranhados neurofibrilares. Fatores genéticos, metabólicos, neuroinflamação, alterações mitocondriais, distúrbios vasculares e processos oxidativos estão envolvidos no desencadear e manutenção de várias doenças neurodegenerativas, incluindo a DA. Todas essas alterações participam no processo fisiopatológico da doença. O objetivo desta revisão é mostrar a associação das várias causas subjacentes ao processo fisiopatológico da DA, com vistas ao desenvolvimento de marcadores biológicos e estratégias terapêuticas.
Alzheimer's disease (AD) is the most common form of sporadic degenerative dementia. Characteristically there is an expressive neuronal loss in specific sites in the affected persons. The progressive degenerative disorder is characterized by synaptic loss, of brain neurons, and by extraneuronal deposition of beta-amyloid fibrils, constituting the senile plaques, and the presence of intraneuronal aggregates of tau protein, forming the neurofibrillary tangles. Genetic factors, metabolic, neuroinflammation, mitochondrial disturbances, vascular disorders and oxidative processes are involved in the onset and maintenance of several neurodegenerative disorders, including AD. All these disturbances participate in the pathophysiological process of the disease. The aim of this review is to show the association of the varied causes underlying the pathophysiological process of AD, having in view the development of biological markers and therapeutic strategies.
Subject(s)
Humans , Aged , Cognition Disorders , Alzheimer Disease/etiology , Alzheimer Disease/physiopathology , Synapses , Amyloid beta-Peptides , Oxidative Stress , Alzheimer Disease/genetics , Mitochondria , Nerve DegenerationABSTRACT
La enfermedad de Alzheimer (EA) es la forma de demencia más común en la edad adulta. Se manifiesta con la pérdida progresiva de la memoria a medida que las neuronas en la corteza cerebral y el hipocampo mueren. En todas las formas de EA se evidencia aumento de la expresión de diferentes proteínas, así como la presencia de agregados insolubles de péptido-β-amiloide (PBA). La glutamina sintetasa (GS) es una enzima clave en el metabolismo del glutamato y en la detoxificación de amonio (NH4+). Previamente se ha reportado una posible interacción GS-PBA que puede estar asociada con EA. En este trabajo se realizó la purificación de la enzima cerebral de rata a partir de un extracto sometido a precipitación fraccionada con (NH4)2SO4 del 20-60 % de saturación y posteriormente a través de cromatografías sucesivas de filtración en gel, intercambio iónico y afinidad. El peso molecular del complejo fue calculado en 137 kDa por el orden de elución en la columna de filtración. Se identificó interacción de la enzima con PBA 1-40, lográndose la purificación de una sola banda de 45 kDa, correspondiente a la forma monomérica de la GS. En este trabajo se presenta un nuevo método de purificación de la enzima y se demuestra la interacción de GS con el PBA. Se propone que esta interacción GS-PBA puede ser uno de los procesos que se presentan en la enfermedad al explicar la reducción de la actividad de la enzima en paciente con EA, ya que podría alterar el ciclo glutamato-glutamina y generar cambios en el entorno celular que favorecen excitotoxicidad por glutamato típica de los procesos de neurodegeneración.
Alzheimer's disease (AD) is the most common form of dementia in adulthood; it is manifested by the progressive loss of memory since neurons in both cerebral cortex and hippocampus die. In all the forms of AD is observed the increased expression of different proteins, as well as the presence of insoluble aggregates of β-amyloid peptide (BAP). Glutamine synthetase (GS) is a key enzyme in the metabolism of glutamate and in the detoxification of ammonium (NH4+). A possible interaction GS-PBA has been previously reported and it can be associated with AD. In this work we performed the purification of the enzyme from rat brain extract subjected to fractional precipitation 20-60 % saturation with (NH4)2SO4, and thereafter through successive chromatographies of gel filtration, ion exchange and affinity. The molecular weight of the complex was calculated at 137 kDa by the order of elution in the column filtration. The interaction of the enzyme with 1-40 PBA was identified, achieving the purification of a single band of 45 kDa corresponding to the monomeric form of the GS. In this paper we present a new method of the enzyme purification and we demonstrated the interaction of GS with the PBA. We propose this interaction GS-PBA can be one of the processes that occur in the disease and it could explain the reduction in enzyme activity in patients with AD, since it might alter the glutamate-glutamine cycle and generate changes in the cellular environment which favor glutamate excitotoxicity typical of neurodegeneration processes.
A doença do Alzhéimer (DA) é a forma mais comum de demência na idade adulta, que se manifesta pela perda progressiva da memória, já que os neurónios em córtex cerebral e hipocampo morrem. Em todas as formas de AD é observado o aumento da expressão de proteínas diferentes, bem como a presença de agregados insolúveis de β-amilóide péptido (BAP). Glutamina sintetase (GS) é uma enzima chave no metabolismo do glutamato e na desintoxicação de amónio (NH4+). Uma possível interacção GS-PBA foi relatada anteriormente e pode ser associada com o AD. Neste trabalho, foi realizada a purificação da enzima a partir do extrato do cérebro de rato e foi submetido a precipitação fraccionada com (NH4)2SO4 de 20- 60 % de saturação e, subsequentemente, através de cromatografias sucessivas de filtração em em gel, permuta iónica e de afinidade. O peso molecular do complexo foi calculado em 137 kDa por ordem de eluição na filtração de coluna. A interacção da enzima com 1-40 PBA foi identificada, alcançando a purificação de uma única banda de 45 kDa correspondente à forma monomérica do GS. Neste artigo, apresentamos um novo método de purificação da enzima e demonstramos a interação da GS com o PBA. Propomos que esta interacção GS-PBA pode ser um dos processos que ocorrem na doença e pode explicar a redução na actividade da enzima nos pacientes com o AD, uma vez que poderia alterar o ciclo de glutamatoglutamina e gerar alterações no ambiente celular que favorecem a excitotoxicidade típica do glutamato nos processos de neurodegeneração.
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Serum p-amyloid peptide(Aβ)40 and Ap42 levels in patients with type 2 diabetes mellitus (T2DM)and atherosclerosis(AS)were detected by ELISA.The results showed that serum Ap40 level in T2DM group was significantly higher than that in the control group[(274.70±159.51 vs 162.63±87.58)pg/ml,P<0.05],especially in the diabetic patients accompanied with AS[(616.95±195.13)pg/m],P<0.01].Serum Ap40 level in simple AS group was also higher than that in control group[(318.52± 188.65)pg/ml,P<0.05].These results suggest that Ap40 is a risk factor of T2DM complicated with AS.However,there was no difference in serum Ap42 levels among various groups.
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Objective To study the effect of ratanasampil (RNSP) which is Traditional Tibetan Medicine on the levels of serum β-amyloid protein, interleukin and tumor necrosis factor alpha (TNF-α) in patients with mild to moderate Alzheimer's disease (AD). Methods One hundred AD patients were divided into two groups in randomized controlled study, including treatment group (RNSP 1 g/d) and control group (piracetam 2.4 g/d). The treatment lasted 12 weeks. The Mini Mental State Examination (MMSE), Alzheimer' s disease Assessment Scale-cognitive subscale (ADAS-cog) and Activity of Daily Living Scale (ADLs) were taken to evaluate the efficacy. Serum levels of amyloid peptides (Aβ40 and Aβ42 ) were measured by ELISA assay. The radioimmunologic assay was used to determine the serum levels of IL-1β, IL-2, IL-6, IL-8 and TNF-α. Results The scores of MMSE, ADAS-cog and ADL significantly improved at 12 weeks after RNSP treatment (P＜0.01, 0.01, 0.05, respectively), while had no significant changes in piracetam group (P＜0.05).The levels of TNF-α, IL-1β, IL-6 and Aβ42 were significantly lower in RNSP group than in Piracetam group (P＜0.01). There was a decrease trend of the Aβ42/Aβ40 ratio at 12 weeks after RNSP treatment (P＜0. 05, P＜0.01 ). The serum Aβ42 level had strong correlations with TNF-α, IL-1 β and IL-6. There were no significant differences in Aβ40 and IL-8 between RNSP group and piracetam group. No obvious drug side effect happened on the groups. Conclusions The reductions of serum TNF-α, IL-1β and IL-6 levels after RNSP treatment may lead to decrease of Aβ42 production in AD patients. RNSP may decrease the Aβ42/Aβ40 ratio and slow down the progress of AD. It may improve the learning and memory ability in treating patients with mild to moderate AD and is well tolerated and safe.
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[Objective] To study effects of the velvet antler polypeptides on spinal nerve cell apoptosis induced by ?-amyloid peptide. [Method]Spinal nerve cells were performed serial subcultivation,and entered into experiment during the exponential phase of growth.The viability of spinal nervecells 24h after induction by ?-amyloid peptide with different concentrations were detected by MTT assay,percentages of the cell apoptosis and expression of casepase-3 were detected after induction by 25?mol/L ?-amyloid peptide.[Result]It was revealed that 24 h after treatment with ?-amyloid peptide of different concentrations,the viability of spinal nerve cells was significantly decreased in a dose-dependent manner(P
ABSTRACT
La enfermedad de Alzheimer es la causa más común de demencia en la población de edad avanzada. Una de las características histopatológicas de esta enfermedad es la formación de placas seniles, cuyo componente proteínico es el péptido β-amiloide (Aβ) en su forma insoluble. Este péptido se produce normalmente en forma monomérica soluble y circula en concentraciones bajas en el líquido cefalorraquídeo y sangre. En concentraciones fisiológicas actúa como factor neurotrófico y neuroprotector, sin embargo con el envejecimiento y sobre todo en la enfermedad de Alzheimer se acumula, forma fibrillas insolubles y causa neurotoxicidad. La toxicidad del Aβ se ha asociado a la generación de radicales libres que causan peroxidación de lípidos y oxidación de proteínas entre otros daños. Se ha planteado que el Aβ pueda reconocer a receptores específicos que median a su vez neurotoxicidad. Entre estos se encuentra el receptor scavenger o pepenador que se expresa en la microglia y es capaz de internalizar agregados de este péptido. Independientemente de la vía de entrada del péptido a la célula, éste genera un estado de estrés oxidativo que eventualmente desencadena la muerte celular. Estudios recientes desarrollados en nuestro laboratorio muestran que el proceso de traducción de proteínas que intervienen en el proceso de endocitosis mediada por un receptor puede ser afectado por una condición de estrés oxidativo. Este es el caso de la β-adaptina, proteína clave en la formación del pozo cubierto.
Alzheimer's disease, the leading cause of dementia in the elderly is characterized by the presence in the brain of senile plaques formed of insoluble fibrillar deposits of beta-amyloid peptide. This peptide is normally produced in a monomeric soluble form and it is present in low concentrations in the blood and spinal fluid. At physiological concentrations, this peptide is a neurotrophic and neuroprotector factor; nevertheless, with aging and particularly in Alzheimer's disease this peptide accumulates, favors the formation of insoluble fibrils and causes neurotoxicity. beta-Amyloid peptide toxicity has been associated with the generation of free radicals that in turn promote lipid peroxidation and protein oxidation. Through the recognition of specific receptors such as the scavenger receptor, the beta-amyloid peptide becomes internalized in the form of aggregates. Independently of the way the peptide enters the cell, it generates oxidative stress that eventually triggers a state of neurotoxicity and cell death. Recent studies in our laboratory have shown the effect caused by an extracellular oxidative stress upon the internalization of the scavenger receptor. We have also demonstrated that the process of protein translation of molecules implicated in the mechanism of endocytosis through the scavenger receptor, such as the case of beta-adaptin, is arrested in microglial cells treated with beta-amyloid.