| 1. |
- Ahl, Matilda, et al.
(författare)
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Immune response in the eye following epileptic seizures
- 2016
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Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. Methods: Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. Results: Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no microglial activation, 6 h post-status epilepticus compared to non-stimulated controls. At 1 week, again, retinal cytoarchitecture appeared normal and there was no cell death or micro- or macroglial reaction, apart from a small decrease in interleukin-10. However, at 7 weeks, even if the cytoarchitecture remained normal and no ongoing cell death was detected, the numbers of microglia were increased ipsi- and contralateral to the epileptic focus. The microglia remained within the synaptic layers but often in clusters and with more processes extending into the outer nuclear layer. Morphological analyses revealed a decrease in surveying and an increase in activated microglia. In addition, increased levels of the chemokine KC/GRO and cytokine interleukin-1β were found. Furthermore, macroglial activation was noted in the inner retina. No alterations in numbers of phagocytic cells, infiltrating macrophages, or vascular pericytes were observed. Post-synaptic density-95 cluster intensity was reduced in the outer nuclear layer, reflecting seizure-induced synaptic changes without disrupted cytoarchitecture in areas with increased microglial activation. The retinal gliosis was decreased by a CX3CR1 immune modulation known to reduce gliosis within epileptic foci, suggesting a common immunological reaction. Conclusions: Our results are the first evidence that epileptic seizures induce an immune response in the retina. It has a potential to become a novel non-invasive tool for detecting brain inflammation through the eyes.
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| 2. |
- Perez-Alcazar, Marta, et al.
(författare)
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Altered cognitive performance and synaptic function in the hippocampus of mice lacking C3.
- 2014
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Ingår i: Experimental neurology. - : Elsevier BV. - 1090-2430 .- 0014-4886. ; 253C, s. 154-164
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Tidskriftsartikel (refereegranskat)abstract
- Previous work implicated the complement system in adult neurogenesis as well as elimination of synapses in the developing and injured CNS. In the present study, we used mice lacking the third complement component (C3) to elucidate the role the complement system plays in hippocampus-dependent learning and synaptic function. We found that the constitutive absence of C3 is associated with enhanced place and reversal learning in adult mice. Our findings of lower release probability at CA3-CA1 glutamatergic synapses in combination with unaltered overall efficacy of these synapses in C3 deficient mice implicate C3 as a negative regulator of the number of functional glutamatergic synapses in the hippocampus. The C3 deficient mice showed no signs of spontaneous epileptiform activity in the hippocampus. We conclude that C3 plays a role in the regulation of the number and function of glutamatergic synapses in the hippocampus and exerts negative effects on hippocampus-dependent cognitive performance.
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| 3. |
- Thored, Pär, et al.
(författare)
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Long-term accumulation of microglia with proneurogenic phenotype concomitant with persistent neurogenesis in adult subventricular zone after stroke
- 2009
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Ingår i: Glia. - Chichester, West Sussex : John Wiley & Sons. - 0894-1491 .- 1098-1136. ; 57:8, s. 835-849
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Tidskriftsartikel (refereegranskat)abstract
- Neural stem cells (NSCs) in the adult rat subventricular zone (SVZ) generate new striatal neurons during several months after ischemic stroke. Whether the microglial response associated with ischemic injury extends into SVZ and influences neuroblast production is unknown. Here, we demonstrate increased numbers of activated microglia in ipsilateral SVZ concomitant with neuroblast migration into the striatum at 2, 6, and 16 weeks, with maximum at 6 weeks, following 2 h middle cerebral artery occlusion in rats. In the peri-infarct striatum, numbers of activated microglia peaked already at 2 weeks and declined thereafter. Microglia in SVZ were resident or originated from bone marrow, with maximum proliferation during the first 2 weeks postinsult. In SVZ, microglia exhibited ramified or intermediate morphology, signifying a downregulated inflammatory profile, whereas amoeboid or round phagocytic microglia were frequent in the peri-infarct striatum. Numbers of microglia expressing markers of antigen-presenting cells (MHC-II, CD86) increased in SVZ but very few lymphocytes were detected. Using quantitative PCR, strong short- and long-term increase (at 1 and 6 weeks postinfarct) of insulin-like growth factor-1 (IGF-1) gene expression was detected in SVZ tissue. Elevated numbers of IGF-1-expressing microglia were found in SVZ at 2, 6, and 16 weeks after stroke. At 16 weeks, 5% of microglia but no other cells in SVZ expressed the IGF-1 protein, which mitigates apoptosis and promotes proliferation and differentiation of NSCs. The long-term accumulation of microglia with proneurogenic phenotype in the SVZ implies a supportive role of these cells for the continuous neurogenesis after stroke.
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| 4. |
- Ajmone-Cat, Maria Antonietta, et al.
(författare)
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Prostaglandin E(2) and BDNF levels in rat hippocampus are negatively correlated with status epilepticus severity: No impact on survival of seizure-generated neurons.
- 2006
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 23:1, s. 23-35
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Tidskriftsartikel (refereegranskat)abstract
- Partial and generalized status epilepticus (pSE and gSE) trigger the same level of progenitor cell proliferation in adult dentate gyrus, but survival of new neurons is poor after gSE. Here, we show markedly elevated levels of prostaglandin E-2 (PGE(2)) and brain-derived neurotrophic factor (BDNF) in rat hippocampal formation at 7 days following pSE but not gSE. Administration of the cyclooxygenase (COX) inhibitor flurbiprofen for 1 week, starting at day 8 post-SE, abated PGE(2) and decreased BDNF levels, but did not affect survival of new neurons a weeks later. Thus, high PGE(2) and BDNF levels induced by pSE are probably not of major importance for survival of new neurons during the first days after formation. We propose that they modulate other aspects of synaptic and cellular plasticity, and thereby may influence epileptogenesis.
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| 5. |
- Ali, Idrish, et al.
(författare)
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Role of fractalkine-CX3CR1 pathway in seizure-induced microglial activation, neurodegeneration, and neuroblast production in the adult rat brain.
- 2015
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 74, s. 194-203
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Tidskriftsartikel (refereegranskat)abstract
- Temporal lobe seizures lead to an acute inflammatory response in the brain primarily characterized by activation of parenchymal microglial cells. Simultaneously, degeneration of pyramidal cells and interneurons is evident together with a seizure-induced increase in the production of new neurons within the dentate gyrus of the hippocampus. We have previously shown a negative correlation between the acute seizure-induced inflammation and the survival of newborn hippocampal neurons. Here, we aimed to evaluate the role of the fractalkine-CX3CR1 pathway for these acute events. Fractalkine is a chemokine expressed by both neurons and glia, while its receptor, CX3CR1 is primarily expressed on microglia. Electrically-induced partial status epilepticus (SE) was induced in adult rats through stereotaxically implanted electrodes in the hippocampus. Recombinant rat fractalkine or CX3CR1 antibody was infused intraventricularly during one week post-SE. A significant increase in the expression of CX3CR1, but not fractalkine, was observed in the dentate gyrus at one week. CX3CR1 antibody treatment resulted in a reduction in microglial activation, neurodegeneration, as well as neuroblast production. In contrast, fractalkine treatment had only minor effects. This study provides evidence for a role of the fractalkine-CX3CR1 signaling pathway in seizure-induced microglial activation and suggests that neuroblast production following seizures may partly occur as a result of microglial activation.
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| 6. |
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| 7. |
- Bengzon, Johan, et al.
(författare)
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Neuronal apoptosis after brief and prolonged seizures.
- 2002
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Ingår i: Progress in Brain Research. - 1875-7855. ; 135, s. 111-119
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Forskningsöversikt (refereegranskat)abstract
- Evidence has accumulated that apoptotic cell death contributes to brain damage following experimental seizures. A substantial number of degenerating neurons within limbic regions display morphological features of apoptosis following prolonged seizures evoked by systemic or local injections of kainic acid, systemic injections of pilocarpine and sustained stimulation of the perforant path. Although longer periods of seizures consistently result in brain damage, it has previously not been clear whether brief single or intermittent seizures lead to cell death. However, recent results indicate that also single seizures lead to apoptotic neuronal death. A brief, non-convulsive seizure evoked by kindling stimulation was found to produce apoptotic neurons bilaterally in the rat dentate gyrus. The mechanism triggering and mediating apoptotic degeneration is at present being studied. Alterations in the expression and activity of cell-death regulatory proteins such as members of the Bcl-2 family and the cysteinyl aspartate-specific proteinase (caspase) family occur in regions vulnerable to cell degeneration, suggesting an involvement of these factors in mediating apoptosis following seizures. Findings of decreased apoptotic cell death following administration of caspase inhibitors prior to and following experimentally induced status epilepticus, further suggest a role for caspases in seizure-evoked neuronal degeneration. Intermediate forms of cell death with both necrotic and apoptotic features have been found after seizures and investigation into the detailed mechanisms of the different forms of cell degeneration is needed before attempts to specific prevention can be made.
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| 8. |
- Biscaro, Barbara, et al.
(författare)
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A beta Immunotherapy Protects Morphology and Survival of Adult-Born Neurons in Doubly Transgenic APP/PS1 Mice
- 2009
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 29:45, s. 14108-14119
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Tidskriftsartikel (refereegranskat)abstract
- The hippocampus is heavily affected by progressive neurodegeneration and beta-amyloid pathology in Alzheimer's disease (AD). The hippocampus is also one of the few brain regions that generate new neurons throughout adulthood. Because hippocampal neurogenesis is regulated by both endogenous and environmental factors, we determined whether it benefits from therapeutic reduction of beta-amyloid peptide (A beta)-related toxicity induced by passive A beta immunotherapy. A beta immunotherapy of 8-9-month-old mice expressing familial AD-causing mutations in the amyloid precursor protein and presenilin-1 genes with an antibody against A beta decreased compact beta-amyloid plaque burden and promoted survival of newly born neurons in the hippocampal dentate gyrus. As these neurons matured, they exhibited longer dendrites with more complex arborization compared with newly born neurons in control-treated transgenic littermates. The newly born neurons showed signs of functional integration indicated by expression of the immediate-early gene Zif268 in response to exposure to a novel object. A beta immunotherapy was associated with higher numbers of synaptophysin-positive synaptic boutons. Labeling dividing progenitor cells with a retroviral vector encoding green fluorescent protein (GFP) showed that A beta immunotherapy restored the impaired dendritic branching, as well as the density of dendritic spines in new mature neurons. The presence of cellular prion protein (PrPc) on the dendrites of the GFP(+) newly born neurons is compatible with a putative role of PrPc in mediating A beta-related toxicity in these cells. In addition, passive A beta immunotherapy was accompanied by increased angiogenesis. Our data establish that passive A beta immunotherapy can restore the morphological maturation of the newly formed neurons in the adult hippocampus and promote angiogenesis. These findings provide evidence for a role of A beta immunotherapy in stimulating neurogenesis and angiogenesis in transgenic mouse models of AD, and they suggest the possibility that A beta immunotherapy can recover neuronal and vascular functions in brains with beta-amyloidosis.
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| 9. |
- Biscaro, Barbara, et al.
(författare)
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Inhibition of Microglial Activation Protects Hippocampal Neurogenesis and Improves Cognitive Deficits in a Transgenic Mouse Model for Alzheimer's Disease
- 2012
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Ingår i: Neurodegenerative Diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 9:4, s. 187-198
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Tidskriftsartikel (refereegranskat)abstract
- Background: Activated microglia with macrophage-like functions invade and surround beta-amyloid (A beta) plaques in Alzheimer's disease (AD), possibly contributing to the turnover of A beta, but they can also secrete proinflammatory factors that may be involved in the pathogenesis of AD. Microglia are known to modulate adult hippocampal neurogenesis. Objectives/Methods: To determine the role of microglia on neurogenesis in brains with A beta pathology, we inhibited microglial activation with the tetracycline derivative minocycline in doubly transgenic mice expressing mutant human amyloid precursor protein (APP) and mutant human presenilin-1 (PS1). Results: Minocycline increased the survival of new dentate granule cells in APP/PS1 mice indicated by more BrdU+/NeuN+ cells as compared to vehicle-treated transgenic littermates, accompanied by improved behavioral performance in a hippocampus-dependent learning task. Both brain levels of A beta and A beta-related morphological deficits in the new neurons labeled with GFP-expressing retrovirus were unaffected in minocycline-treated mice. Conclusions: These results suggest a role for microglia in A beta-related functional deficits and in suppressing the survival of new neurons, and show that modulation of microglial function with minocycline can protect hippocampal neurogenesis in the presence of A beta pathology. Copyright (C) 2012 S. Karger AG, Basel
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| 10. |
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