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Beta-amyloid 25-35 peptide reduces the expression of glutamine transporter SAT1 in cultured cortical neurons.

ABSTRACT: Beta-amyloid (Abeta) peptides may cause malfunction and death of neurons in Alzheimer's disease. We investigated the effect of Abeta on key transporters of amino acid neurotransmission in cells cultured from rat cerebral cortex. The cultures were treated with Abeta(25-35) at 3 and 10 microM for 12 and 24 h followed by quantitative analysis of immunofluorescence intensity. In mixed neuronal-glial cell cultures (from P1 rats), Abeta reduced the concentration of system A glutamine transporter 1 (SAT1), by up to 50% expressed relative to the neuronal marker microtubule-associated protein 2 (MAP2) in the same cell. No significant effects were detected on vesicular glutamate transporters VGLUT1 or VGLUT2 in neurons, or on glial system N glutamine transporter 1 (SN1). In neuronal cell cultures (from E18 rats), Abeta(25-35) did not reduce SAT1 immunoreactivity, suggesting that the observed effect depends on the presence of astroglia. The results indicate that Abeta may impair neuronal function and transmitter synthesis, and perhaps reduce excitotoxicity, through a reduction in neuronal glutamine uptake.

SUBMITTER: Buntup D

PROVIDER: S-EPMC2226019 | biostudies-other | 2008 Feb

REPOSITORIES: biostudies-other

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Cilostazol prevents amyloid ? peptide(25-35)-induced memory impairment and oxidative stress in mice.

Project description:Background and purposeCilostazol may be effective in dementia associated with a cerebral ischaemia. In this study, we examined whether it exerts beneficial effects on learning and/or memory impairment induced by A?(25-35) in mice, and compared its effects with those of aspirin.Experimental approachA?(25-35) (9?nmol) was administered to mice i.c.v. Learning and memory behaviour were evaluated by measuring spontaneous alternation in a Y-maze and a step-down type passive avoidance test, on the 5th and 8th days after injection respectively. Levels of lipid peroxidation (malondialdehyde) and cytokines in the frontal cortex and hippocampus were measured 2, 3, 5 and 7 days after the A?(25-35) injection. The effects of repeated administration of cilostazol and aspirin (both at 30 and 100?mg·kg(-1), p.o.) on any changes induced by A?(25-35) were evaluated.Key resultsRepeated administration of cilostazol significantly attenuated the impairment of spontaneous alternation and the shortened step-down latency induced by A?(25-35) . Aspirin did not show any beneficial effect. A significant increase in the levels of malondialdehyde (MDA) and IL-1? (only measured in hippocampus) was observed 2, 3 and 5 days after the A?(25-35) injection in the frontal cortex and hippocampus. Repeated administration of cilostazol (100?mg·kg(-1)) completely prevented the increase in MDA levels but failed to antagonize the increase in the expression of IL-1? induced by A?(25-35).Conclusions and implicationsThese results suggest that the protective effect of cilostazol on A?(25-35)-induced memory impairment may be related to oxidative stress in the frontal cortex and the hippocampus.

| S-EPMC3010591 | biostudies-literature

Effects of solvent on the structure of the Alzheimer amyloid-beta(25-35) peptide.

Project description:The free energy landscape for folding of the Alzheimer's amyloid-beta(25-35) peptide is explored using replica exchange molecular dynamics in both pure water and in HFIP/water cosolvent. This amphiphilic peptide is a natural by-product of the Alzheimer's amyloid-beta(1-40) peptide and retains the toxicity of its full-length counterpart as well as the ability to aggregate into beta-sheet-rich fibrils. Our simulations reveal that the peptide preferentially populates a helical structure in apolar organic solvent, while in pure water, the peptide adopts collapsed coil conformations and to a lesser extent beta-hairpin conformations. The beta-hairpin is characterized by a type II' beta-turn involving residues G29 and A30 and two short beta-strands involving residues N27, K28, I31, and I32. The hairpin is stabilized by backbone hydrogen-bonding interactions between residues K28 and I31; S26 and G33; and by side-chain-to-side-chain interactions between N27 and I32. Implications regarding the mechanism of aggregation of this peptide into fibrils and the role of the environment in modulating secondary structure are discussed.

| S-EPMC1544315 | biostudies-literature

Transcription profiling of rat astrocytes cultured on the beta-amyloid peptide 25-35 fragment for 12 hours, 1, 3 and 5 days

Project description:Cortical type-I astrocytes were cultured on the beta-amyloid peptide 25-35 fragment for 12hr, 1d, 3d, and 5d.

2007-10-12 | E-GEOD-856 | biostudies-arrayexpress

Amyloid-beta peptide (25-35) triggers a reorganization of lipid membranes driven by temperature changes.

Project description:The amyloid-beta peptide (Aβ) is considered a key factor in Alzheimer's disease (AD) ever since the discovery of the disease. The understanding of its damaging influence has however shifted recently from large fibrils observed in the inter-cellular environment to the small oligomers interacting with a cell membrane. We studied the effect of temperature on the latter interactions by evaluating the structural characteristics of zwitterionic phosphatidylcholine (PC) membranes with incorporated Aβ25-35 peptide. By means of small angle neutron scattering (SANS), we have observed for the first time a spontaneous reformation of extruded unilamellar vesicles (EULVs) to discoidal bicelle-like structures (BLSs) and small unilamellar vesicles (SULVs). These changes in the membrane self-organization happen during the thermodynamic phase transitions of lipids and only in the presence of the peptide. We interpret the dramatic changes in the membrane's overall shape with parallel changes in its thickness as the Aβ25-35 triggered membrane damage and a consequent reorganization of its structure. The suggested process is consistent with an action of separate peptides or small size peptide oligomers rather than the result of large Aβ fibrils.

| S-EPMC8578324 | biostudies-literature

Beta-amyloid increases the expression level of ATBF1 responsible for death in cultured cortical neurons.

Project description:BackgroundRecently, several lines of evidence have shown the aberrant expression of cell-cycle-related proteins and tumor suppressor proteins in vulnerable neurons of the Alzheimer's disease (AD) brain and transgenic mouse models of AD; these proteins are associated with various paradigms of neuronal death. It has been reported that ATBF1 induces cell cycle arrest associated with neuronal differentiation in the developing rat brain, and that gene is one of the candidate tumor suppressor genes for prostate and breast cancers in whose cells overexpressed ATBF1 induces cell cycle arrest. However, the involvement of ATBF1 in AD pathogenesis is as yet unknown.ResultsWe found that ATBF1 was up-regulated in the brains of 17-month-old Tg2576 mice compared with those of age-matched wild-type mice. Moreover, our in vitro studies showed that Aβ1-42 and DNA-damaging drugs, namely, etoposide and homocysteine, increased the expression ATBF1 level in primary rat cortical neurons, whereas the knockdown of ATBF1 in these neurons protected against neuronal death induced by Aβ1-42, etoposide, and homocysteine, indicating that ATBF1 mediates neuronal death in response to these substances. In addition, we found that ATBF1-mediated neuronal death is dependent on ataxia-telangiectasia mutated (ATM) because the blockage of ATM activity by treatment with ATM inhibitors, caffeine and KU55933, abolished ATBF1 function in neuronal death. Furthermore, Aβ1-42 phosphorylates ATM, and ATBF1 interacts with phosphorylated ATM.ConclusionsTo the best of our knowledge, this is the first report that Aβ1-42 and DNA-damaging drugs increased the ATBF1 expression level in primary rat cortical neurons; this increase, in turn, may activate ATM signaling responsible for neuronal death through the binding of ATBF1 to phosphorylated ATM. ATBF1 may therefore be a suitable target for therapeutic intervention of AD.

| S-EPMC3145572 | biostudies-literature

Role of ?-hairpin formation in aggregation: the self-assembly of the amyloid-?(25-35) peptide.

Project description:The amyloid-?(25-35) peptide plays a key role in the etiology of Alzheimer's disease due to its extreme toxicity even in the absence of aging. Because of its high tendency to aggregate and its low solubility in water, the structure of this peptide is still unknown. In this work, we sought to understand the early stages of aggregation of the amyloid-?(25-35) peptide by conducting simulations of oligomers ranging from monomers to tetramers. Our simulations show that although the monomer preferentially adopts a ?-hairpin conformation, larger aggregates have extended structures, and a clear transition from compact ?-hairpin conformations to extended ?-strand structures occurs between dimers and trimers. Even though ?-hairpins are not present in the final architecture of the fibril, our simulations indicate that they play a critical role in fibril growth. Our simulations also show that ?-sheet structures are stabilized when a ?-hairpin is present at the edge of the sheet. The binding of the hairpin to the sheet leads to a subsequent destabilization of the hairpin, with part of the hairpin backbone dangling in solution. This free section of the peptide can then recruit an extra monomer from solution, leading to further sheet extension. Our simulations indicate that the peptide must possess sufficient conformational flexibility to switch between a hairpin and an extended conformation in order for ?-sheet extension to occur, and offer a rationalization for the experimental observation that overstabilizing a hairpin conformation in the monomeric state (for example, through chemical cross-linking) significantly hampers the fibrillization process.

| S-EPMC3414875 | biostudies-other

Interaction of the β amyloid - Aβ(25-35) - peptide with zwitterionic and negatively charged vesicles with and without cholesterol.

Project description:The interactions of the Alzheimer's β-amyloid peptide, Aβ(25-35), with 18:1 (Δ9-Cis) PC 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), L-α-phosphatidylcholine (EPC), 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DOPG), and L-α-phosphatidylglycerol (EPG) phospholipid vesicles with and without cholesterol (Ch) are studied by the nitroxide spin probe electron paramagnetic resonance (EPR) method. Two nitroxide spin probes, 2,2,6,6-tetramethyl-piperidin-1-oxyl-4-yl hexadecanoate (TP, TEMPO-Palmitate) and 2-Ethyl-2-(15-methoxy-15-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy (16-DSE), are utilized in the study. TEMPO-Palmitate has the reporting EPR moiety located at the top of this spin probe, while 16-DSE has the reporting EPR moiety located at the tail of the spin probe. These two probes enable us to sample the surface and the middle of the phospholipid bilayer, respectively. All EPR measurements are done above the melting points of all four phospholipids when the bilayer is in the liquid crystal phase, the physiologically relevant phase. Due to non-linear spectral line fitting, the EPR spectral parameters are extracted with high precision. The results show that there are two populations of Aβ(25-35) and that one of them is located in the hydrophobic phospholipid layer below the hydrophilic headgroup region. The second population appears to be weakly coupled to the surface of the bilayer. Both hydrophobic and electrostatic interactions affect the insertion of Aβ(25-35) in the bilayer. Also, there is strong evidence for an interaction between cholesterol and Aβ(25-35), which affects the dielectric and dynamic properties of the bilayer.

| S-EPMC6342288 | biostudies-literature

Brain-transportable soy dipeptide, Tyr-Pro, attenuates amyloid β peptide<sub>25-35</sub>-induced memory impairment in mice.

Project description:In this study, experiments on amyloid β peptide25-35-induced mice were performed to provide in vivo evidence on the potential of the blood-brain barrier transportable soy dipeptide, Tyr-Pro, in combating memory impairment. We demonstrated for the first time that oral administration of Tyr-Pro (100 mg/kg, twice a day) in mice for 16 days significantly improved impaired memory by spontaneous alternation and shortened step-through latency in amyloid β-induced mice.

| S-EPMC7195433 | biostudies-literature

Hippocampal neurons in direct contact with astrocytes exposed to amyloid β<sub>25-35</sub> exhibit reduced excitatory synaptic transmission.

Project description:Amyloid β protein (Aβ) is closely related to the progression of Alzheimer's disease because senile plaques consisting of Aβ cause synaptic depression and synaptic abnormalities. In the central nervous system, astrocytes are a major glial cell type that contribute to the modulation of synaptic transmission and synaptogenesis. In this study, we examined whether astrocytes exposed to Aβ fragment 25-35 (Aβ25-35) affect synaptic transmission. We show that synaptic transmission by hippocampal neurons was inhibited by astrocytes exposed to Aβ25-35. The Aβ25-35-exposed astrocytes lowered excitatory postsynaptic release and the size of the readily releasable synaptic pool. The number of excitatory synapses was also reduced. However, the number of excitatory synapses was unchanged unless there was direct contact between Aβ25-35-exposed astrocytes and hippocampal neurons. These data indicate that direct contact between Aβ25-35-exposed astrocytes and neurons is critical for inhibiting synaptic transmission in the progression of Alzheimer's disease.

| S-EPMC6669318 | biostudies-literature

Intracerebroventricular administration of oxytocin and intranasal administration of the oxytocin derivative improve β-amyloid peptide (25-35)-induced memory impairment in mice.

Project description:AimWe previously reported that oxytocin, a peptide hormone, can reverse the β-amyloid peptide (25-35) (Aβ25-35 )-induced impairments of the murine hippocampal synaptic plasticity. In this study, we examined the effects of oxytocin on the Aβ25-35 -induced impairment of cognitive behavior in murine in order to investigate the potential of oxytocin as a clinical treatment tool for Alzheimer's disease (AD).MethodsThe Y-maze and Morris water maze (MWM) tests were performed. Since the intracerebroventricular (ICV) administration is both invasive and impractical, we further utilized intranasal (IN) delivery to the brain. For this purpose, we prepared an oxytocin derivative containing cell-penetrating peptides and a penetration accelerating sequence, which was subsequently used in our IN administration experiments.ResultsWe herein showed that the ICV administration of oxytocin in mice exerted memory-improving effects on the Aβ25-35 -induced amnesia in both the Y-maze and MWM tests. The IN administration of the oxytocin derivative exhibited memory-improving effects in the Y-maze test. Moreover, we acquired evidence that the fluorescein isothiocyanate-labeled oxytocin derivative was distributed throughout the mouse brain following its IN administration.ConclusionOur results suggest that the oxytocin derivative is effective for its IN delivery to the brain and may be particularly useful in the clinical treatment of cognitive impairment, such as that characterizing AD.

| S-EPMC9773650 | biostudies-literature

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