Effects of 3,3',5-triiodothyronine on microglial functions.

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Mori, Yuki; Tomonaga, Daichi; Kalashnikova, Anastasia; Furuya, Fumihiko; Akimoto, Nozomi; Ifuku, Masataka; Okuno, Yuko; Beppu, Kaoru; Fujita, Kyota; Katafuchi, Toshihiko; Shimura, Hiroki; Churilov, Leonid P; Noda, Mami

2015-05-01

L-tri-iodothyronine (3, 3', 5-triiodothyronine; T3) is an active form of the thyroid hormone (TH) essential for the development and function of the CNS. Though nongenomic effect of TH, its plasma membrane-bound receptor, and its signaling has been identified, precise function in each cell type of the CNS remained to be investigated. Clearance of cell debris and apoptotic cells by microglia phagocytosis is a critical step for the restoration of damaged neuron-glia networks. Here we report nongenomic effects of T3 on microglial functions. Exposure to T3 increased migration, membrane ruffling and phagocytosis of primary cultured mouse microglia. Injection of T3 together with stab wound attracted more microglia to the lesion site in vivo. Blocking TH transporters and receptors (TRs) or TRα-knock-out (KO) suppressed T3-induced microglial migration and morphological change. The T3-induced microglial migration or membrane ruffling was attenuated by inhibiting Gi /o -protein as well as NO synthase, and subsequent signaling such as phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK). Inhibitors for Na(+) /K(+) -ATPase, reverse mode of Na(+) /Ca(2+) exchanger (NCX), and small-conductance Ca(2+) -dependent K(+) (SK) channel also attenuated microglial migration or phagocytosis. Interestingly, T3-induced microglial migration, but not phagocytosis, was dependent on GABAA and GABAB receptors, though GABA itself did not affect migratory aptitude. Our results demonstrate that T3 modulates multiple functional responses of microglia via multiple complex mechanisms, which may contribute to physiological and/or pathophysiological functions of the CNS. © 2015 Wiley Periodicals, Inc.

Acutely damaged axons are remyelinated in multiple sclerosis and experimental models of demyelination.

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Schultz, Verena; van der Meer, Franziska; Wrzos, Claudia; Scheidt, Uta; Bahn, Erik; Stadelmann, Christine; Brück, Wolfgang; Junker, Andreas

2017-08-01

Remyelination is in the center of new therapies for the treatment of multiple sclerosis to resolve and improve disease symptoms and protect axons from further damage. Although remyelination is considered beneficial in the long term, it is not known, whether this is also the case early in lesion formation. Additionally, the precise timing of acute axonal damage and remyelination has not been assessed so far. To shed light onto the interrelation between axons and the myelin sheath during de- and remyelination, we employed cuprizone- and focal lysolecithin-induced demyelination and performed time course experiments assessing the evolution of early and late stage remyelination and axonal damage. We observed damaged axons with signs of remyelination after cuprizone diet cessation and lysolecithin injection. Similar observations were made in early multiple sclerosis lesions. To assess the correlation of remyelination and axonal damage in multiple sclerosis lesions, we took advantage of a cohort of patients with early and late stage remyelinated lesions and assessed the number of APP- and SMI32- positive damaged axons and the density of SMI31-positive and silver impregnated preserved axons. Early de- and remyelinating lesions did not differ with respect to axonal density and axonal damage, but we observed a lower axonal density in late stage demyelinated multiple sclerosis lesions than in remyelinated multiple sclerosis lesions. Our findings suggest that remyelination may not only be protective over a long period of time, but may play an important role in the immediate axonal recuperation after a demyelinating insult. © 2017 The Authors GLIA Published by Wiley Periodicals, Inc.

Conspicuity of diffuse axonal injury lesions on diffusion-weighted MR imaging

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Kinoshita, Toshibumi; Moritani, Toshio; Hiwatashi, Akio; Wang, Henry Z.; Shrier, David A.; Numaguchi, Yuji; Westesson, Per-Lennart A.

2005-01-01

Objective: (1) To detect diffuse axonal injury (DAI) lesions by diffusion-weighted imaging (DWI), as compared with fluid-attenuated inversion recovery (FLAIR) imaging and (2) to evaluate hemorrhagic DAI lesions by b 0 images obtained from DWI, as compared with gradient-echo (GRE) imaging. Methods: We reviewed MR images of 36 patients with a diagnosis of DAI. MR imaging was performed 20 h to 14 days (mean, 3.7 days) after traumatic brain injury. We evaluated: (1) conspicuity of lesions on DWI and FLAIR and (2) conspicuity of hemorrhage in DAI lesions on b 0 images and GRE imaging. Results: DWI clearly depicted high-signal DAI lesions. The sensitivity of DWI to lesional conspicuity in DAI lesions was almost equal to that of FLAIR. The sensitivity of b 0 images to identification of hemorrhagic DAI lesions was inferior to that of GRE. Conclusion: DWI is as useful as FLAIR in detecting DAI lesions. GRE imaging is still the superior tool for the evaluation of hemorrhagic DAI

[Facial nerve injuries cause changes in central nervous system microglial cells].

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Cerón, Jeimmy; Troncoso, Julieta

2016-12-01

Our research group has described both morphological and electrophysiological changes in motor cortex pyramidal neurons associated with contralateral facial nerve injury in rats. However, little is known about those neural changes, which occur together with changes in surrounding glial cells. To characterize the effect of the unilateral facial nerve injury on microglial proliferation and activation in the primary motor cortex. We performed immunohistochemical experiments in order to detect microglial cells in brain tissue of rats with unilateral facial nerve lesion sacrificed at different times after the injury. We caused two types of lesions: reversible (by crushing, which allows functional recovery), and irreversible (by section, which produces permanent paralysis). We compared the brain tissues of control animals (without surgical intervention) and sham-operated animals with animals with lesions sacrificed at 1, 3, 7, 21 or 35 days after the injury. In primary motor cortex, the microglial cells of irreversibly injured animals showed proliferation and activation between three and seven days post-lesion. The proliferation of microglial cells in reversibly injured animals was significant only three days after the lesion. Facial nerve injury causes changes in microglial cells in the primary motor cortex. These modifications could be involved in the generation of morphological and electrophysiological changes previously described in the pyramidal neurons of primary motor cortex that command facial movements.

Conspicuity of diffuse axonal injury lesions on diffusion-weighted MR imaging

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Kinoshita, Toshibumi [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States)]. E-mail: kino@grape.med.tottori-u.ac.jp; Moritani, Toshio [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States); Hiwatashi, Akio [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States); Wang, Henry Z. [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States); Shrier, David A. [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States); Numaguchi, Yuji [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States); Westesson, Per-Lennart A. [Department of Radiology, Division of Neuroradiology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 648, Rochester, NY 14642 (United States)

2005-10-01

Objective: (1) To detect diffuse axonal injury (DAI) lesions by diffusion-weighted imaging (DWI), as compared with fluid-attenuated inversion recovery (FLAIR) imaging and (2) to evaluate hemorrhagic DAI lesions by b{sub 0} images obtained from DWI, as compared with gradient-echo (GRE) imaging. Methods: We reviewed MR images of 36 patients with a diagnosis of DAI. MR imaging was performed 20 h to 14 days (mean, 3.7 days) after traumatic brain injury. We evaluated: (1) conspicuity of lesions on DWI and FLAIR and (2) conspicuity of hemorrhage in DAI lesions on b{sub 0} images and GRE imaging. Results: DWI clearly depicted high-signal DAI lesions. The sensitivity of DWI to lesional conspicuity in DAI lesions was almost equal to that of FLAIR. The sensitivity of b{sub 0} images to identification of hemorrhagic DAI lesions was inferior to that of GRE. Conclusion: DWI is as useful as FLAIR in detecting DAI lesions. GRE imaging is still the superior tool for the evaluation of hemorrhagic DAI.

Fingolimod modulates microglial activation to augment markers of remyelination

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Baker David

2011-07-01

Full Text Available Abstract Introduction Microglial activation in multiple sclerosis has been postulated to contribute to long-term neurodegeneration during disease. Fingolimod has been shown to impact on the relapsing remitting phase of disease by modulating autoreactive T-cell egress from lymph organs. In addition, it is brain penetrant and has been shown to exert multiple effects on nervous system cells. Methods In this study, the impact of fingolimod and other sphingosine-1-phosphate receptor active molecules following lysophosphotidyl choline-induced demyelination was examined in the rat telencephalon reaggregate, spheroid cell culture system. The lack of immune system components allowed elucidation of the direct effects of fingolimod on CNS cell types in an organotypic situation. Results Following demyelination, fingolimod significantly augmented expression of myelin basic protein in the remyelination phase. This increase was not associated with changes in neurofilament levels, indicating de novo myelin protein expression not associated with axonal branching. Myelin wrapping was confirmed morphologically using confocal and electron microscopy. Increased remyelination was associated with down-regulation of microglial ferritin, tumor necrosis factor alpha and interleukin 1 during demyelination when fingolimod was present. In addition, nitric oxide metabolites and apoptotic effectors caspase 3 and caspase 7 were reduced during demyelination in the presence of fingolimod. The sphingosine-1-phosphate receptor 1 and 5 agonist BAF312 also increased myelin basic protein levels, whereas the sphingosine-1-phosphate receptor 1 agonist AUY954 failed to replicate this effect on remyelination. Conclusions The results presented indicate that modulation of S1P receptors can ameliorate pathological effectors associated with microglial activation leading to a subsequent increase in protein and morphological markers of remyelination. In addition, sphingosine-1-phosphate

Chondroitin sulfates do not impede axonal regeneration in goldfish spinal cord.

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Takeda, Akihito; Okada, Soichiro; Funakoshi, Kengo

2017-10-15

Chondroitin sulfate proteoglycans produced in glial scar tissue are a major inhibitory factor for axonal regeneration after central nervous system injury in mammals. The inhibition is largely due to chondroitin sulfates, whose effects differ according to the sulfation pattern. In contrast to mammals, fish nerves spontaneously regenerate beyond the scar tissue after spinal cord injury, although the mechanisms that allow for axons to pass through the scar are unclear. Here, we used immunohistochemistry to examine the expression of two chondroitin sulfates with different sulfation variants at the lesion site in goldfish spinal cord. The intact spinal cord was immunoreactive for both chondroitin sulfate-A (CS-A) and chondroitin sulfate-C (CS-C), and CS-A immunoreactivity overlapped extensively with glial processes positive for glial fibrillary acidic protein. At 1week after inducing the spinal lesion, CS-A immunoreactivity was observed in the cell bodies and extracellular matrix, as well as in glial processes surrounding the lesion center. At 2weeks after the spinal lesion, regenerating axons entering the lesion center overtook the CS-A abundant area. In contrast, at 1week after lesion induction, CS-C immunoreactivity was significantly decreased, and at 2weeks after lesion induction, CS-C immunoreactivity was observed along the regenerating axons entering the lesion center. The present findings suggest that after spinal cord injury in goldfish, chondroitin sulfate proteoglycans are deposited in the extracellular matrix at the lesion site but do not form an impenetrable barrier to the growth of regenerating axons. Copyright © 2017 Elsevier B.V. All rights reserved.

Microglial involvement in neuroplastic changes following focal brain ischemia in rats.

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Alexandre Madinier

2009-12-01

Full Text Available The pathogenesis of ischemic stroke is a complex sequence of events including inflammatory reaction, for which the microglia appears to be a major cellular contributor. However, whether post-ischemic activation of microglial cells has beneficial or detrimental effects remains to be elucidated, in particular on long term brain plasticity events. The objective of our study was to determine, through modulation of post-stroke inflammatory response, to what extent microglial cells are involved in some specific events of neuronal plasticity, neurite outgrowth and synaptogenesis. Since microglia is a source of neurotrophic factors, the identification of the brain-derived neurophic factor (BDNF as possible molecular actor involved in these events was also attempted. As a means of down-regulating the microglial response induced by ischemia, 3-aminobenzamide (3-AB, 90 mg/kg, i.p. was used to inhibit the poly(ADP-ribose polymerase-1 (PARP-1. Indeed, PARP-1 contributes to the activation of the transcription factor NF-kB, which is essential to the upregulation of proinflammatory genes, in particular responsible for microglial activation/proliferation. Experiments were conducted in rats subjected to photothrombotic ischemia which leads to a strong and early microglial cells activation/proliferation followed by an infiltration of macrophages within the cortical lesion, events evaluated at serial time points up to 1 month post-ictus by immunostaining for OX-42 and ED-1. Our most striking finding was that the decrease in acute microglial activation induced by 3-AB was associated with a long term down-regulation of two neuronal plasticity proteins expression, synaptophysin (marker of synaptogenesis and GAP-43 (marker of neuritogenesis as well as to a significant decrease in tissue BDNF production. Thus, our data argue in favour of a supportive role for microglia in brain neuroplasticity stimulation possibly through BDNF production, suggesting that a targeted

Poly(ADP-ribosepolymerase-1 modulates microglial responses to amyloid β

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Kauppinen Tiina M

2011-11-01

Full Text Available Abstract Background Amyloid β (Aβ accumulates in Alzheimer's disease (AD brain. Microglial activation also occurs in AD, and this inflammatory response may contribute to disease progression. Microglial activation can be induced by Aβ, but the mechanisms by which this occurs have not been defined. The nuclear enzyme poly(ADP-ribose polymerase-1 (PARP-1 regulates microglial activation in response to several stimuli through its interactions with the transcription factor, NF-κB. The purpose of this study was to evaluate whether PARP-1 activation is involved in Aβ-induced microglial activation, and whether PARP-1 inhibition can modify microglial responses to Aβ. Methods hAPPJ20 mice, which accumulate Aβ with ageing, were crossed with PARP-1-/- mice to assess the effects of PARP-1 depletion on microglial activation, hippocampal synaptic integrity, and cognitive function. Aβ peptide was also injected into brain of wt and PARP-1-/- mice to directly determine the effects of PARP-1 on Aβ-induced microglial activation. The effect of PARP-1 on Aβ-induced microglial cytokine production and neurotoxicity was evaluated in primary microglia cultures and in microglia-neuron co-cultures, utilizing PARP-1-/- cells and a PARP-1 inhibitor. NF-κB activation was evaluated in microglia infected with a lentivirus reporter gene. Results The hAPPJ20 mice developed microglial activation, reduced hippocampal CA1 calbindin expression, and impaired novel object recognition by age 6 months. All of these features were attenuated in hAPPJ20/PARP-1-/- mice. Similarly, Aβ1-42 injected into mouse brain produced a robust microglial response in wild-type mice, and this was blocked in mice lacking PARP-1 expression or activity. Studies using microglial cultures showed that PARP-1 activity was required for Aβ-induced NF-κB activation, morphological transformation, NO release, TNFα release, and neurotoxicity. Conversely, PARP-1 inhibition increased release of the

Protective Effects of Curcumin on Manganese-Induced BV-2 Microglial Cell Death.

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Park, Euteum; Chun, Hong Sung

2017-08-01

Curcumin, a bioactive component in tumeric, has been shown to exert antioxidant, anti-inflammatory, anticarcinogenic, hepatoprotective, and neuroprotective effects, but the effects of curcumin against manganese (Mn)-mediated neurotoxicity have not been studied. This study examined the protective effects of curcumin on Mn-induced cytotoxicity in BV-2 microglial cells. Curcumin (0.1-10 µM) dose-dependently prevented Mn (250 µM)-induced cell death. Mn-induced mitochondria-related apoptotic characteristics, such as caspase-3 and -9 activation, cytochrome c release, Bax increase, and Bcl-2 decrease, were significantly suppressed by curcumin. In addition, curcumin significantly increased intracellular glutathione (GSH) and moderately potentiated superoxide dismutase (SOD), both which were diminished by Mn treatment. Curcumin pretreatment effectively suppressed Mn-induced upregulation of malondialdehyde (MDA), total reactive oxygen species (ROS). Moreover, curcumin markedly inhibited the Mn-induced mitochondrial membrane potential (MMP) loss. Furthermore, curcumin was able to induce heme oxygenase (HO)-1 expression. Curcumin-mediated inhibition of ROS, down-regulation of caspases, restoration of MMP, and recovery of cell viability were partially reversed by HO-1 inhibitor (SnPP). These results suggest the first evidence that curcumin can prevent Mn-induced microglial cell death through the induction of HO-1 and regulation of oxidative stress, mitochondrial dysfunction, and apoptotic events.

Dependence of regenerated sensory axons on continuous neurotrophin-3 delivery.

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Hou, Shaoping; Nicholson, LaShae; van Niekerk, Erna; Motsch, Melanie; Blesch, Armin

2012-09-19

Previous studies have shown that injured dorsal column sensory axons extend across a spinal cord lesion site if axons are guided by a gradient of neurotrophin-3 (NT-3) rostral to the lesion. Here we examined whether continuous NT-3 delivery is necessary to sustain regenerated axons in the injured spinal cord. Using tetracycline-regulated (tet-off) lentiviral gene delivery, NT-3 expression was tightly controlled by doxycycline administration. To examine axon growth responses to regulated NT-3 expression, adult rats underwent a C3 dorsal funiculus lesion. The lesion site was filled with bone marrow stromal cells, tet-off-NT-3 virus was injected rostral to the lesion site, and the intrinsic growth capacity of sensory neurons was activated by a conditioning lesion. When NT-3 gene expression was turned on, cholera toxin β-subunit-labeled sensory axons regenerated into and beyond the lesion/graft site. Surprisingly, the number of regenerated axons significantly declined when NT-3 expression was turned off, whereas continued NT-3 expression sustained regenerated axons. Quantification of axon numbers beyond the lesion demonstrated a significant decline of axon growth in animals with transient NT-3 expression, only some axons that had regenerated over longer distance were sustained. Regenerated axons were located in white matter and did not form axodendritic synapses but expressed presynaptic markers when closely associated with NG2-labeled cells. A decline in axon density was also observed within cellular grafts after NT-3 expression was turned off possibly via reduction in L1 and laminin expression in Schwann cells. Thus, multiple mechanisms underlie the inability of transient NT-3 expression to fully sustain regenerated sensory axons.

Omega-3 polyunsaturated fatty acid supplementation attenuates microglial-induced inflammation by inhibiting the HMGB1/TLR4/NF-κB pathway following experimental traumatic brain injury.

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Chen, Xiangrong; Wu, Shukai; Chen, Chunnuan; Xie, Baoyuan; Fang, Zhongning; Hu, Weipeng; Chen, Junyan; Fu, Huangde; He, Hefan

2017-07-24

Microglial activation and the subsequent inflammatory response in the central nervous system play important roles in secondary damage after traumatic brain injury (TBI). High-mobility group box 1 (HMGB1) protein, an important mediator in late inflammatory responses, interacts with transmembrane receptor for advanced glycation end products (RAGE) and toll-like receptors (TLRs) to activate downstream signaling pathways, such as the nuclear factor (NF)-κB signaling pathway, leading to a cascade amplification of inflammatory responses, which are related to neuronal damage after TBI. Omega-3 polyunsaturated fatty acid (ω-3 PUFA) is a commonly used clinical immunonutrient, which has antioxidative and anti-inflammatory effects. However, the effects of ω-3 PUFA on HMGB1 expression and HMGB1-mediated activation of the TLR4/NF-κB signaling pathway are not clear. The Feeney DM TBI model was adopted to induce brain injury in rats. Modified neurological severity scores, brain water content, and Nissl staining were employed to determine the neuroprotective effects of ω-3 PUFA supplementation. Assessment of microglial activation in lesioned sites and protein markers for proinflammatory, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, interferon (IFN)-γ, and HMGB1 were used to evaluate neuroinflammatory responses and anti-inflammation effects of ω-3 PUFA supplementation. Immunofluorescent staining and western blot analysis were used to detect HMGB1 nuclear translocation, secretion, and HMGB1-mediated activation of the TLR4/NF-κB signaling pathway to evaluate the effects of ω-3 PUFA supplementation and gain further insight into the mechanisms underlying the development of the neuroinflammatory response after TBI. It was found that ω-3 PUFA supplementation inhibited TBI-induced microglial activation and expression of inflammatory factors (TNF-α, IL-1β, IL-6, and IFN-γ), reduced brain edema, decreased neuronal apoptosis, and improved neurological

Blast overpressure induced axonal injury changes in rat brainstem and spinal cord

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Srinivasu Kallakuri

2015-01-01

Full Text Available Introduction: Blast induced neurotrauma has been the signature wound in returning soldiers from the ongoing wars in Iraq and Afghanistan. Of importance is understanding the pathomechansim(s of blast overpressure (OP induced axonal injury. Although several recent animal models of blast injury indicate the neuronal and axonal injury in various brain regions, animal studies related to axonal injury in the white matter (WM tracts of cervical spinal cord are limited. Objective: The purpose of this study was to assess the extent of axonal injury in WM tracts of cervical spinal cord in male Sprague Dawley rats subjected to a single insult of blast OP. Materials and Methods: Sagittal brainstem sections and horizontal cervical spinal cord sections from blast and sham animals were stained by neurofilament light (NF-L chain and beta amyloid precursor protein immunocytochemistry and observed for axonal injury changes. Results: Observations from this preliminary study demonstrate axonal injury changes in the form of prominent swellings, retraction bulbs, and putative signs of membrane disruptions in the brainstem and cervical spinal cord WM tracts of rats subjected to blast OP. Conclusions: Prominent axonal injury changes following the blast OP exposure in brainstem and cervical spinal WM tracts underscores the need for careful evaluation of blast induced injury changes and associated symptoms. NF-L immunocytochemistry can be considered as an additional tool to assess the blast OP induced axonal injury.

Enlarging the nosological spectrum of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS).

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Hoffmann, Sarah; Murrell, Jill; Harms, Lutz; Miller, Kelly; Meisel, Andreas; Brosch, Thomas; Scheel, Michael; Ghetti, Bernardino; Goebel, Hans-Hilmar; Stenzel, Werner

2014-09-01

Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is an autosomal dominant disease clinically characterized by cognitive decline, personality changes, motor impairment, parkinsonism and seizures. Recently, mutations in the colony-stimulating factor-1 receptor (CSF1R) gene have been shown to be associated with HDLS. We report clinical, neuropathological and molecular genetic findings of patients from a new family with a mutation in the CSF1R gene. Disease onset was earlier and disease progression was more rapid compared with previously reported patients. Psychiatric symptoms including personality changes, alcohol abuse and severe depression were the first symptoms in male patients. In the index, female patient, the initial symptom was cognitive decline. Magnetic resonance imaging (MRI) showed bilateral, confluent white matter lesions in the cerebrum. Stereotactic biopsy revealed loss of myelin and microglial activation as well as macrophage infiltration of the parenchyma. Numerous axonal swellings and spheroids were present. Ultrastructural analysis revealed pigment-containing macrophages. Axonal swellings were detected by electron microscopy not only in the central nervous system (CNS) but also in skin nerves. We identified a heterozygous mutation (c.2330G>A, p.R777Q) in the CSF1R gene. Through this report, we aim to enlarge the nosological spectrum of HDLS, providing new clinical descriptions as well as novel neuropathological findings from the peripheral nervous system. © 2014 International Society of Neuropathology.

Paraquat and maneb co-exposure induces noradrenergic locus coeruleus neurodegeneration through NADPH oxidase-mediated microglial activation

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Hou, Liyan; Zhang, Cong; Wang, Ke; Liu, Xiaofang; Wang, Hongwei; Che, Yuning; Sun, Fuqiang; Zhou, Xueying; Zhao, Xiulan; Wang, Qingshan

2017-01-01

Highlights: • Microglial activation induced by paraquat and maneb precedes noradrenergic neurodegeneration in locus coeruleus. • NADPH oxidase activation contributes to microglia-mediated neuroinflammation and related noradrenergic neurodegeneration. • Inhibition of NADPH oxidase by apocynin protects noradrenergic neurons against paraquat and maneb-induced toxicity. - Abstract: Co-exposure to paraquat (PQ) and maneb (Mb) has been shown to increase the risk of Parkinson’s disease (PD) and dopaminergic (DA) neurodegeneration in the substantia nigra pars compacta (SNpc) is observed in PQ and Mb-treated experimental animals. The loss of noradrenergic locus coeruleus (LC/NE) neurons in brainstem is a common feature shared by multiple neurodegenerative diseases, including PD. However, whether PQ and Mb is able to damage LC/NE neurons remains undefined. In this study, mice treated with combined PQ and Mb displayed progressive LC/NE neurodegeneration. Time course studies revealed that the activation of microglia preceded LC/NE neurodegeneration. Mechanistically, the activation of NADPH oxidase contributed to microglial activation and subsequent LC/NE neurodegeneration. We found that PQ and Mb co-exposure induced activation of NADPH oxidase as shown by increased superoxide production and membrane translocation of p47 phox , a cytosolic subunit of NADPH oxidase. Inhibition of NADPH oxidase by apocynin, a widely used NADPH oxidase inhibitor, suppressed microglial activation and gene expressions of proinflammatory factors. Furthermore, reduced activation of nuclear factor-κB (NF-κB) pathway was observed in apocynin-treated mice. More importantly, inhibition of NADPH oxidase by apocynin afforded LC/NE neuroprotection against PQ and Mb-induced neurotoxicity. Thus, our findings revealed the critical role NADPH oxidase-mediated microglial activation in driving LC/NE neurodegeneration induced by PQ and Mb, providing new insights into the pathogenesis of environmental

Anti-inflammatory Effects of Curcumin in Microglial Cells

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Yangyang Yu

2018-04-01

Full Text Available Lipoteichoic acid (LTA induces neuroinflammatory molecules, contributing to the pathogenesis of neurodegenerative diseases. Therefore, suppression of neuroinflammatory molecules could be developed as a therapeutic method. Although previous data supports an immune-modulating effect of curcumin, the underlying signaling pathways are largely unidentified. Here, we investigated curcumin’s anti-neuroinflammatory properties in LTA-stimulated BV-2 microglial cells. Inflammatory cytokine tumor necrosis factor-α [TNF-α, prostaglandin E2 (PGE2, and Nitric Oxide (NO] secretion in LTA-induced microglial cells were inhibited by curcumin. Curcumin also inhibited LTA-induced inducible NO synthases (iNOS and cyclooxygenase-2 (COX-2 expression. Subsequently, our mechanistic studies revealed that curcumin inhibited LTA-induced phosphorylation of mitogen-activated protein kinase (MAPK including ERK, p38, Akt and translocation of NF-κB. Furthermore, curcumin induced hemeoxygenase (HO-1HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf-2 expression in microglial cells. Inhibition of HO-1 reversed the inhibition effect of HO-1 on inflammatory mediators release in LTA-stimulated microglial cells. Taken together, our results suggest that curcumin could be a potential therapeutic agent for the treatment of neurodegenerative disorders via suppressing neuroinflammatory responses.

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

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Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China); Wei, Ling [Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Liu, Yutong [School of Life Science, Beijing Normal University, Beijing 100875 (China); Liao, Jieying [Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024 (China); Gao, Hui-Ming [Model Animal Research Center of Nanjing University, Nanjing 211800 (China); Zhou, Hui, E-mail: hardhui@gmail.com [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China)

2017-05-01

Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

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Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin; Wei, Ling; Liu, Yutong; Liao, Jieying; Gao, Hui-Ming; Zhou, Hui

2017-01-01

Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm 2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm 2 ) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91 phox , p47 phox and p40 phox ); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47 phox and p67 phox translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our

Telomere dysfunction reduces microglial numbers without fully inducing an aging phenotype

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Khan, Asif Manzoor; Babcock, Alicia; Saeed, Hamid

2015-01-01

The susceptibility of the aging brain to neurodegenerative disease may in part be attributed to cellular aging of the microglial cells that survey it. We investigated the effect of cellular aging induced by telomere shortening on microglia by the use of mice lacking the telomerase RNA component...... (TERC) and design-based stereology. TERC knockout (KO) mice had a significantly reduced number of CD11b(+) microglia in the dentate gyrus. Because of an even greater reduction in dentate gyrus volume, microglial density was, however, increased. Microglia in TERC KO mice maintained a homogenous...... distribution and normal expression of CD45 and CD68 and the aging marker, ferritin, but were morphologically distinct from microglia in both adult and old wild-type mice. TERC KO mice also showed increased cellular apoptosis and impaired spatial learning. Our results suggest that individual microglia...

Salidroside Reduces Cell Mobility via NF-κB and MAPK Signaling in LPS-Induced BV2 Microglial Cells

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Haixia Hu

2014-01-01

Full Text Available The unregulated activation of microglia following stroke results in the production of toxic factors that propagate secondary neuronal injury. Salidroside has been shown to exhibit protective effects against neuronal death induced by different insults. However, the molecular mechanisms responsible for the anti-inflammatory activity of salidroside have not been elucidated clearly in microglia. In the present study, we investigated the molecular mechanism underlying inhibiting LPS-stimulated BV2 microglial cell mobility of salidroside. The protective effect of salidroside was investigated in microglial BV2 cell, subjected to stretch injury. Moreover, transwell migration assay demonstrated that salidroside significantly reduced cell motility. Our results also indicated that salidroside suppressed LPS-induced chemokines production in a dose-dependent manner, without causing cytotoxicity in BV2 microglial cells. Moreover, salidroside suppressed LPS-induced activation of nuclear factor kappa B (NF-κB by blocking degradation of IκBα and phosphorylation of MAPK (p38, JNK, ERK1/2, which resulted in inhibition of chemokine expression. These results suggest that salidroside possesses a potent suppressive effect on cell migration of BV2 microglia and this compound may offer substantial therapeutic potential for treatment of ischemic strokes that are accompanied by microglial activation.

Regulatory effects of fisetin on microglial activation.

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Chuang, Jing-Yuan; Chang, Pei-Chun; Shen, Yi-Chun; Lin, Chingju; Tsai, Cheng-Fang; Chen, Jia-Hong; Yeh, Wei-Lan; Wu, Ling-Hsuan; Lin, Hsiao-Yun; Liu, Yu-Shu; Lu, Dah-Yuu

2014-06-26

Increasing evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play a key role in neurodegeneration. Fisetin, a plant flavonol commonly found in fruits and vegetables, is frequently added to nutritional supplements due to its antioxidant properties. In the present study, treatment with fisetin inhibited microglial cell migration and ROS (reactive oxygen species) production. Treatment with fisetin also effectively inhibited LPS plus IFN-γ-induced nitric oxide (NO) production, and inducible nitric oxide synthase (iNOS) expression in microglial cells. Furthermore, fisetin also reduced expressions of iNOS and NO by stimulation of peptidoglycan, the major component of the Gram-positive bacterium cell wall. Fisetin also inhibited the enhancement of LPS/IFN-γ- or peptidoglycan-induced inflammatory mediator IL (interlukin)-1 β expression. Besides the antioxidative and anti-inflammatory effects of fisetin, our study also elucidates the manner in fisetin-induced an endogenous anti-oxidative enzyme HO (heme oxygenase)-1 expression. Moreover, the regulatory molecular mechanism of fisetin-induced HO-1 expression operates through the PI-3 kinase/AKT and p38 signaling pathways in microglia. Notably, fisetin also significantly attenuated inflammation-related microglial activation and coordination deficit in mice in vivo. These findings suggest that fisetin may be a candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.

Regulatory Effects of Fisetin on Microglial Activation

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Jing-Yuan Chuang

2014-06-01

Full Text Available Increasing evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play a key role in neurodegeneration. Fisetin, a plant flavonol commonly found in fruits and vegetables, is frequently added to nutritional supplements due to its antioxidant properties. In the present study, treatment with fisetin inhibited microglial cell migration and ROS (reactive oxygen species production. Treatment with fisetin also effectively inhibited LPS plus IFN-γ-induced nitric oxide (NO production, and inducible nitric oxide synthase (iNOS expression in microglial cells. Furthermore, fisetin also reduced expressions of iNOS and NO by stimulation of peptidoglycan, the major component of the Gram-positive bacterium cell wall. Fisetin also inhibited the enhancement of LPS/IFN-γ- or peptidoglycan-induced inflammatory mediator IL (interlukin-1 β expression. Besides the antioxidative and anti-inflammatory effects of fisetin, our study also elucidates the manner in fisetin-induced an endogenous anti-oxidative enzyme HO (heme oxygenase-1 expression. Moreover, the regulatory molecular mechanism of fisetin-induced HO-1 expression operates through the PI-3 kinase/AKT and p38 signaling pathways in microglia. Notably, fisetin also significantly attenuated inflammation-related microglial activation and coordination deficit in mice in vivo. These findings suggest that fisetin may be a candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.

Peripheral viral infection induced microglial sensome genes and enhanced microglial cell activity in the hippocampus of neonatal piglets

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Ji, Peng; Schachtschneider, Kyle M.; Schook, Lawrence B.; Walker, Frederick R.; Johnson, Rodney W.

2016-01-01

Although poorly understood, early-life infection is predicted to affect brain microglial cells, making them hypersensitive to subsequent stimuli. To investigate this, we assessed gene expression in hippocampal tissue obtained from a previously published study reporting increased microglial cell

Macrophage colony-stimulating factor and its receptor signaling augment glycated albumin-induced retinal microglial inflammation in vitro

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Jiang Chun H

2011-01-01

Full Text Available Abstract Background Microglial activation and the proinflammatory response are controlled by a complex regulatory network. Among the various candidates, macrophage colony-stimulating factor (M-CSF is considered an important cytokine. The up-regulation of M-CSF and its receptor CSF-1R has been reported in brain disease, as well as in diabetic complications; however, the mechanism is unclear. An elevated level of glycated albumin (GA is a characteristic of diabetes; thus, it may be involved in monocyte/macrophage-associated diabetic complications. Results The basal level of expression of M-CSF/CSF-1R was examined in retinal microglial cells in vitro. Immunofluorescence, real-time PCR, immunoprecipitation, and Western blot analyses revealed the up-regulation of CSF-1R in GA-treated microglial cells. We also detected increased expression and release of M-CSF, suggesting that the cytokine is produced by activated microglia via autocrine signaling. Using an enzyme-linked immunosorbent assay, we found that GA affects microglial activation by stimulating the release of tumor necrosis factor-α and interleukin-1β. Furthermore, the neutralization of M-CSF or CSF-1R with antibodies suppressed the proinflammatory response. Conversely, this proinflammatory response was augmented by the administration of M-CSF. Conclusions We conclude that GA induces microglial activation via the release of proinflammatory cytokines, which may contribute to the inflammatory pathogenesis of diabetic retinopathy. The increased microglial expression of M-CSF/CSF-1R not only is a response to microglial activation in diabetic retinopathy but also augments the microglial inflammation responsible for the diabetic microenvironment.

Layer 5 Pyramidal Neurons’ Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis

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Diana Urrego

2015-01-01

Full Text Available This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1. It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans.

Layer 5 Pyramidal Neurons' Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis

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Urrego, Diana; Troncoso, Julieta; Múnera, Alejandro

2015-01-01

This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1). It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans. PMID:26064916

Motor Axonal Regeneration After Partial and Complete Spinal Cord Transection

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Lu, Paul; Blesch, Armin; Graham, Lori; Wang, Yaozhi; Samara, Ramsey; Banos, Karla; Haringer, Verena; Havton, Leif; Weishaupt, Nina; Bennett, David; Fouad, Karim; Tuszynski, Mark H.

2012-01-01

We subjected rats to either partial mid-cervical or complete upper thoracic spinal cord transections and examined whether combinatorial treatments support motor axonal regeneration into and beyond the lesion. Subjects received cAMP injections into brainstem reticular motor neurons to stimulate their endogenous growth state, bone marrow stromal cell grafts in lesion sites to provide permissive matrices for axonal growth, and brain-derived neurotrophic factor (BDNF) gradients beyond the lesion to stimulate distal growth of motor axons. Findings were compared to several control groups. Combinatorial treatment generated motor axon regeneration beyond both C5 hemisection and complete transection sites. Yet despite formation of synapses with neurons below the lesion, motor outcomes worsened after partial cervical lesions and spasticity worsened after complete transection. These findings highlight the complexity of spinal cord repair, and the need for additional control and shaping of axonal regeneration. PMID:22699902

A homologous form of human interleukin 16 is implicated in microglia recruitment following nervous system injury in leech Hirudo medicinalis.

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Croq, Françoise; Vizioli, Jacopo; Tuzova, Marina; Tahtouh, Muriel; Sautiere, Pierre-Eric; Van Camp, Christelle; Salzet, Michel; Cruikshank, William W; Pestel, Joel; Lefebvre, Christophe

2010-11-01

In contrast to mammals, the medicinal leech Hirudo medicinalis can completely repair its central nervous system (CNS) after injury. This invertebrate model offers unique opportunities to study the molecular and cellular basis of the CNS repair processes. When the leech CNS is injured, microglial cells migrate and accumulate at the site of lesion, a phenomenon known to be essential for the usual sprouting of injured axons. In the present study, we demonstrate that a new molecule, designated HmIL-16, having functional homologies with human interleukin-16 (IL-16), has chemotactic activity on leech microglial cells as observed using a gradient of human IL-16. Preincubation of microglial cells either with an anti-human IL-16 antibody or with anti-HmIL-16 antibody significantly reduced microglia migration induced by leech-conditioned medium. Functional homology was demonstrated further by the ability of HmIL-16 to promote human CD4+ T cell migration which was inhibited by antibody against human IL-16, an IL-16 antagonist peptide or soluble CD4. Immunohistochemistry of leech CNS indicates that HmIL-16 protein present in the neurons is rapidly transported and stored along the axonal processes to promote the recruitment of microglial cells to the injured axons. To our knowledge, this is the first identification of a functional interleukin-16 homologue in invertebrate CNS. The ability of HmIL-16 to recruit microglial cells to sites of CNS injury suggests a role for HmIL-16 in the crosstalk between neurons and microglia in the leech CNS repair.

Environmental Subconcussive Injury, Axonal Injury, and Chronic Traumatic Encephalopathy

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Wendy A. Morley

2018-03-01

Full Text Available Brain injury occurs in two phases: the initial injury itself and a secondary cascade of precise immune-based neurochemical events. The secondary phase is typically functional in nature and characterized by delayed axonal injury with more axonal disconnections occurring than in the initial phase. Axonal injury occurs across the spectrum of disease severity, with subconcussive injury, especially when repetitive, now considered capable of producing significant neurological damage consistent with axonal injury seen in clinically evident concussion, despite no observable symptoms. This review is the first to introduce the concept of environmental subconcussive injury (ESCI and sets out how secondary brain damage from ESCI once past the juncture of microglial activation appears to follow the same neuron-damaging pathway as secondary brain damage from conventional brain injury. The immune response associated with ESCI is strikingly similar to that mounted after conventional concussion. Specifically, microglial activation is followed closely by glutamate and calcium flux, excitotoxicity, reactive oxygen species and reactive nitrogen species (RNS generation, lipid peroxidation, and mitochondrial dysfunction and energy crisis. ESCI damage also occurs in two phases, with the primary damage coming from microbiome injury (due to microbiome-altering events and secondary damage (axonal injury from progressive secondary neurochemical events. The concept of ESCI and the underlying mechanisms have profound implications for the understanding of chronic traumatic encephalopathy (CTE etiology because it has previously been suggested that repetitive axonal injury may be the primary CTE pathogenesis in susceptible individuals and it is best correlated with lifetime brain trauma load. Taken together, it appears that susceptibility to brain injury and downstream neurodegenerative diseases, such as CTE, can be conceptualized as a continuum of brain resilience. At one end

Zinc Oxide Nanoparticle Induces Microglial Death by NADPH-Oxidase-Independent Reactive Oxygen Species as well as Energy Depletion.

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Sharma, Anuj Kumar; Singh, Vikas; Gera, Ruchi; Purohit, Mahaveer Prasad; Ghosh, Debabrata

2017-10-01

Zinc oxide nanoparticle (ZnO-NP) is one of the most widely used engineered nanoparticles. Upon exposure, nanoparticle can eventually reach the brain through various routes, interact with different brain cells, and alter their activity. Microglia is the fastest glial cell to respond to any toxic insult. Nanoparticle exposure can activate microglia and induce neuroinflammation. Simultaneous to activation, microglial death can exacerbate the scenario. Therefore, we focused on studying the effect of ZnO-NP on microglia and finding out the pathway involved in the microglial death. The present study showed that the 24 h inhibitory concentration 50 (IC 50 ) of ZnO-NP for microglia is 6.6 μg/ml. Early events following ZnO-NP exposure involved increase in intracellular calcium level as well as reactive oxygen species (ROS). Neither of NADPH oxidase inhibitors, apocynin, (APO) and diphenyleneiodonium chloride (DPIC) were able to reduce the ROS level and rescue microglia from ZnO-NP toxicity. In contrary, N-acetyl cysteine (NAC) showed opposite effect. Exogenous supplementation of superoxide dismutase (SOD) reduced ROS significantly even beyond control level but partially rescued microglial viability. Interestingly, pyruvate supplementation rescued microglia near to control level. Following 10 h of ZnO-NP exposure, intracellular ATP level was measured to be almost 50 % to the control. ZnO-NP-induced ROS as well as ATP depletion both disturbed mitochondrial membrane potential and subsequently triggered the apoptotic pathway. The level of apoptosis-inducing proteins was measured by western blot analysis and found to be upregulated. Taken together, we have deciphered that ZnO-NP induced microglial apoptosis by NADPH oxidase-independent ROS as well as ATP depletion.

Increased slow transport in axons of regenerating newt limbs after a nerve conditioning lesion made prior to amputation

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Maier, C.E.

1989-01-01

The first part of this study shows that axonal density is constant in the limb stump of the next proximal to the area of traumatic nerve degeneration caused by limb amputation. The results of the second part of this work reveal that a nerve conditioning lesion made two weeks prior to amputation is associated with accelerated limb regeneration and that this accelerated limb regeneration is accompanied by an earlier arrival of axons. This is the first demonstration of naturally occurring limb regeneration being enhanced. In this study SCb cytoskeletal proteins were identified and measured using SDS-PAGE and liquid scintillation counting. Proteins were measured at 7, 14, 21, and 28 days after 35 S-methionine injection and the normal rate of SCb transport determined to be 0.19 mm/day. A single axotomy does not enhance the rate of SCb transport but does increase the amount of labeled SCb proteins that are transported. When a conditioning lesion is employed prior to limb amputation and SCb proteins are measured at 7, 14, and 21 days after injection, there is a twofold acceleration in the rate of SCb transport and an increase in the amount of SCb proteins transported in conditioned axons

Microglial phagocytosis induced by fibrillar β-amyloid is attenuated by oligomeric β-amyloid: implications for Alzheimer's disease

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Lin Nan

2011-06-01

Full Text Available Abstract Background Reactive microglia are associated with β-amyloid (Aβ deposit and clearance in Alzhiemer's Disease (AD. Paradoxically, entocranial resident microglia fail to trigger an effective phagocytic response to clear Aβ deposits although they mainly exist in an "activated" state. Oligomeric Aβ (oAβ, a recent target in the pathogenesis of AD, can induce more potent neurotoxicity when compared with fibrillar Aβ (fAβ. However, the role of the different Aβ forms in microglial phagocytosis, induction of inflammation and oxidation, and subsequent regulation of phagocytic receptor system, remain unclear. Results We demonstrated that Aβ(1-42 fibrils, not Aβ(1-42 oligomers, increased the microglial phagocytosis. Intriguingly, the pretreatment of microglia with oAβ(1-42 not only attenuated fAβ(1-42-triggered classical phagocytic response to fluorescent microspheres but also significantly inhibited phagocytosis of fluorescent labeled fAβ(1-42. Compared with the fAβ(1-42 treatment, the oAβ(1-42 treatment resulted in a rapid and transient increase in interleukin 1β (IL-1β level and produced higher levels of tumor necrosis factor-α (TNF-α, nitric oxide (NO, prostaglandin E2 (PGE2 and intracellular superoxide anion (SOA. The further results demonstrated that microglial phagocytosis was negatively correlated with inflammatory mediators in this process and that the capacity of phagocytosis in fAβ(1-42-induced microglia was decreased by IL-1β, lippolysaccharide (LPS and tert-butyl hydroperoxide (t-BHP. The decreased phagocytosis could be relieved by pyrrolidone dithiocarbamate (PDTC, a nuclear factor-κB (NF-κB inhibitor, and N-acetyl-L-cysteine (NAC, a free radical scavenger. These results suggest that the oAβ-impaired phagocytosis is mediated through inflammation and oxidative stress-mediated mechanism in microglial cells. Furthermore, oAβ(1-42 stimulation reduced the mRNA expression of CD36, integrin β1 (Itgb1, and Ig

Stimulation of cannabinoid receptor 2 (CB2 suppresses microglial activation

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Fernandez Francisco

2005-12-01

Full Text Available Abstract Background Activated microglial cells have been implicated in a number of neurodegenerative disorders, including Alzheimer's disease (AD, multiple sclerosis (MS, and HIV dementia. It is well known that inflammatory mediators such as nitric oxide (NO, cytokines, and chemokines play an important role in microglial cell-associated neuron cell damage. Our previous studies have shown that CD40 signaling is involved in pathological activation of microglial cells. Many data reveal that cannabinoids mediate suppression of inflammation in vitro and in vivo through stimulation of cannabinoid receptor 2 (CB2. Methods In this study, we investigated the effects of a cannabinoid agonist on CD40 expression and function by cultured microglial cells activated by IFN-γ using RT-PCR, Western immunoblotting, flow cytometry, and anti-CB2 small interfering RNA (siRNA analyses. Furthermore, we examined if the stimulation of CB2 could modulate the capacity of microglial cells to phagocytise Aβ1–42 peptide using a phagocytosis assay. Results We found that the selective stimulation of cannabinoid receptor CB2 by JWH-015 suppressed IFN-γ-induced CD40 expression. In addition, this CB2 agonist markedly inhibited IFN-γ-induced phosphorylation of JAK/STAT1. Further, this stimulation was also able to suppress microglial TNF-α and nitric oxide production induced either by IFN-γ or Aβ peptide challenge in the presence of CD40 ligation. Finally, we showed that CB2 activation by JWH-015 markedly attenuated CD40-mediated inhibition of microglial phagocytosis of Aβ1–42 peptide. Taken together, these results provide mechanistic insight into beneficial effects provided by cannabinoid receptor CB2 modulation in neurodegenerative diseases, particularly AD.

Lipoprotein Lipase Maintains Microglial Innate Immunity in Obesity

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Yuanqing Gao

2017-09-01

Full Text Available Consumption of a hypercaloric diet upregulates microglial innate immune reactivity along with a higher expression of lipoprotein lipase (Lpl within the reactive microglia in the mouse brain. Here, we show that knockdown of the Lpl gene specifically in microglia resulted in deficient microglial uptake of lipid, mitochondrial fuel utilization shifting to glutamine, and significantly decreased immune reactivity. Mice with knockdown of the Lpl gene in microglia gained more body weight than control mice on a high-carbohydrate high-fat (HCHF diet. In these mice, microglial reactivity was significantly decreased in the mediobasal hypothalamus, accompanied by downregulation of phagocytic capacity and increased mitochondrial dysmorphologies. Furthermore, HCHF-diet-induced POMC neuronal loss was accelerated. These results show that LPL-governed microglial immunometabolism is essential to maintain microglial function upon exposure to an HCHF diet. In a hypercaloric environment, lack of such an adaptive immunometabolic response has detrimental effects on CNS regulation of energy metabolism.

Fractalkine Attenuates Microglial Cell Activation Induced by Prenatal Stress

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Joanna Ślusarczyk

2016-01-01

Full Text Available The potential contribution of inflammation to the development of neuropsychiatric diseases has recently received substantial attention. In the brain, the main immune cells are the microglia. As they are the main source of inflammatory factors, it is plausible that the regulation of their activation may be a potential therapeutic target. Fractalkine (CX3CL1 and its receptor CX3CR1 play a crucial role in the control of the biological activity of the microglia. In the present study, using microglial cultures we investigated whether fractalkine is able to reverse changes in microglia caused by a prenatal stress procedure. Our study found that the microglia do not express fractalkine. Prenatal stress decreases the expression of the fractalkine receptor, which in turn is enhanced by the administration of exogenous fractalkine. Moreover, treatment with fractalkine diminishes the prenatal stress-induced overproduction of proinflammatory factors such as IL-1β, IL-18, IL-6, TNF-α, CCL2, or NO in the microglial cells derived from prenatally stressed newborns. In conclusion, the present results revealed that the pathological activation of microglia in prenatally stressed newborns may be attenuated by fractalkine administration. Therefore, understanding of the role of the CX3CL1-CX3CR1 system may help to elucidate the mechanisms underlying the neuron-microglia interaction and its role in pathological conditions in the brain.

Characterizing Signals within Lesions and Mapping Brain Network Connectivity After Traumatic Axonal Injury: A 7 Tesla Resting-State FMRI Study.

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Lee, Seul; Polimeni, Jonathan R; Price, Collin M; Edlow, Brian L; McNab, Jennifer A

2018-04-18

Resting-state functional magnetic resonance imaging (RS-FMRI) has been widely used to map brain functional connectivity, but it is unclear how to probe connectivity within and around lesions. Here we characterize RS-FMRI signal time-course properties and evaluate different seed placements within and around hemorrhagic traumatic axonal injury lesions. RS-FMRI was performed on a 7 Tesla scanner in a patient who recovered consciousness after traumatic coma and in three healthy controls. Eleven lesions in the patient were characterized in terms of: 1) temporal signal-to-noise ratio (tSNR); 2) physiological noise, through comparison of noise regressors derived from the white matter (WM), cerebrospinal fluid (CSF) and gray matter (GM); and 3) seed-based functional connectivity. Temporal SNR at the center of the lesions was 38.3% and 74.1% lower compared to the same region in the contralesional hemisphere of the patient and in the ipsilesional hemispheres of the controls, respectively. Within the lesions, WM noise was more prominent than CSF and GM noise. Lesional seeds did not produce discernable networks, but seeds in the contralesional hemisphere revealed networks whose nodes appeared to be shifted or obscured due to overlapping or nearby lesions. Single-voxel seed analysis demonstrated that placing a seed within a lesion's periphery was necessary to identify networks associated with the lesion region. These findings provide evidence of resting-state network changes in the human brain after recovery from traumatic coma. Further, we show that seed placement within a lesion's periphery or in the contralesional hemisphere may be necessary for network identification in patients with hemorrhagic traumatic axonal injury.

The role of MAC1 in diesel exhaust particle-induced microglial activation and loss of dopaminergic neuron function.

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Levesque, Shannon; Taetzsch, Thomas; Lull, Melinda E; Johnson, Jo Anne; McGraw, Constance; Block, Michelle L

2013-06-01

Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson's disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (neuron function was assessed. All three treatments showed enhanced ameboid microglia morphology, increased H2 O2 production, and decreased DA uptake. Mechanistic inquiry revealed that the scavenger receptor inhibitor fucoidan blocked DEP internalization in microglia, but failed to alter DEP-induced H2 O2 production in microglia. However, pre-treatment with the MAC1/CD11b inhibitor antibody blocked microglial H2 O2 production in response to DEP. MAC1(-/-) mesencephalic neuron-glia cultures were protected from DEP-induced loss of DA neuron function, as measured by DA uptake. These findings support that DEP may activate microglia through multiple mechanisms, where scavenger receptors regulate internalization of DEP and the MAC1 receptor is mandatory for both DEP-induced microglial H2 O2 production and loss of DA neuron function. © 2013 International Society for Neurochemistry.

Botanical Polyphenols Mitigate Microglial Activation and Microglia-Induced Neurotoxicity: Role of Cytosolic Phospholipase A2.

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Chuang, Dennis Y; Simonyi, Agnes; Cui, Jiankun; Lubahn, Dennis B; Gu, Zezong; Sun, Grace Y

2016-09-01

Microglia play a significant role in the generation and propagation of oxidative/nitrosative stress, and are the basis of neuroinflammatory responses in the central nervous system. Upon stimulation by endotoxins such as lipopolysaccharides (LPS), these cells release pro-inflammatory factors which can exert harmful effects on surrounding neurons, leading to secondary neuronal damage and cell death. Our previous studies demonstrated the effects of botanical polyphenols to mitigate inflammatory responses induced by LPS, and highlighted an important role for cytosolic phospholipase A2 (cPLA2) upstream of the pro-inflammatory pathways (Chuang et al. in J Neuroinflammation 12(1):199, 2015. doi: 10.1186/s12974-015-0419-0 ). In this study, we investigate the action of botanical compounds and assess whether suppression of cPLA2 in microglia is involved in the neurotoxic effects on neurons. Differentiated SH-SY5Y neuroblastoma cells were used to test the neurotoxicity of conditioned medium from stimulated microglial cells, and WST-1 assay was used to assess for the cell viability of SH-SY5Y cells. Botanicals such as quercetin and honokiol (but not cyanidin-3-O-glucoside, 3CG) were effective in inhibiting LPS-induced nitric oxide (NO) production and phosphorylation of cPLA2. Conditioned medium from BV-2 cells stimulated with LPS or IFNγ caused neurotoxicity to SH-SY5Y cells. Decrease in cell viability could be ameliorated by pharmacological inhibitors for cPLA2 as well as by down-regulating cPLA2 with siRNA. Botanicals effective in inhibition of LPS-induced NO and cPLA2 phosphorylation were also effective in ameliorating microglial-induced neurotoxicity. Results demonstrated cytotoxic factors from activated microglial cells to cause damaging effects to neurons and potential use of botanical polyphenols to ameliorate the neurotoxic effects.

Effects of X-irradiation on axonal sprouting induced by botulinum toxin

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Gomez, S; Duchen, L W [National Hospital, London (UK); Hornsey, S [Hammersmith Hospital, London (UK). M.R.C. Cyclotron Unit

1982-01-01

The effect of X-irradiation on axonal sprouting of motor nerves induced by botulinum toxin was examined. Muscles of one leg in the mouse were X-irradiated (15Gy) prior to the injection of a locally paralysing dose of botulinum toxin. It was found that axonal sprouting occurred as expected, but the sprouts remained unmyelinated and many degenerated. Fewer new end-plates were formed, muscles remained more severely atrophied and supersensitive to acetylcholine and recovery of neuromuscular transmission was greatly delayed when compared with the effects of botulinum toxin alone. X-irradiation did not prevent sprouting but, probably by impairing Schwann cell proliferation, altered axon-Schwann cell relationships and prevented the maturation of newly-formed axons and the differentiation of new end-plates.

Evaluation of the Effect of Fingolimod Treatment on Microglial Activation Using Serial PET Imaging in Multiple Sclerosis.

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Sucksdorff, Marcus; Rissanen, Eero; Tuisku, Jouni; Nuutinen, Salla; Paavilainen, Teemu; Rokka, Johanna; Rinne, Juha; Airas, Laura

2017-10-01

Traditionally, multiple sclerosis (MS) has been considered a white matter disease with focal inflammatory lesions. It is, however, becoming clear that significant pathology, such as microglial activation, also takes place outside the plaque areas, that is, in areas of normal-appearing white matter (NAWM) and gray matter (GM). Microglial activation can be detected in vivo using 18-kDa translocator protein (TSPO)-binding radioligands and PET. It is unknown whether fingolimod affects microglial activation in MS. The aim of this study was to investigate whether serial PET can be used to evaluate the effect of fingolimod treatment on microglial activation. Methods: Ten relapsing-remitting MS patients were studied using the TSPO radioligand 11 C-( R )-PK11195. Imaging was performed at baseline and after 8 and 24 wk of fingolimod treatment. Eight healthy individuals were imaged for comparison. Microglial activation was evaluated as distribution volume ratio of 11 C-( R )-PK11195. Results: The patients had MS for an average of 7.9 ± 4.3 y (mean ± SD), their total relapses averaged 4 ± 2.4, and their Expanded Disability Status Scale was 2.7 ± 0.5. The patients were switched to fingolimod because of safety reasons or therapy escalation. The mean washout period before the initiation of fingolimod was 2.3 ± 1.1 mo. The patients were clinically stable on fingolimod. At baseline, microglial activation was significantly higher in the combined NAWM and GM areas of MS patients than in healthy controls ( P = 0.021). 11 C-( R )-PK11195 binding was reduced (-12.31%) within the combined T2 lesion area after 6 mo of fingolimod treatment ( P = 0.040) but not in the areas of NAWM or GM. Conclusion: Fingolimod treatment reduced microglial/macrophage activation at the site of focal inflammatory lesions, presumably by preventing leukocyte trafficking from the periphery. It did not affect the widespread, diffuse microglial activation in the NAWM and GM. The study opens new vistas for

Serotonin induces memory-like, rapamycin-sensitive hyperexcitability in sensory axons of aplysia that contributes to injury responses.

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Weragoda, Ramal M S; Walters, Edgar T

2007-09-01

The induction of long-term facilitation (LTF) of synapses of Aplysia sensory neurons (SNs) by serotonin (5-HT) has provided an important mechanistic model of memory, but little is known about other long-term effects of 5-HT on sensory properties. Here we show that crushing peripheral nerves results in long-term hyperexcitability (LTH) of the axons of these nociceptive SNs that requires 5-HT activity in the injured nerve. Serotonin application to a nerve segment induces local axonal (but not somal) LTH that is inhibited by 5-HT-receptor antagonists. Blockade of crush-induced axonal LTH by an antagonist, methiothepin, provides evidence for mediation of this injury response by 5-HT. This is the first demonstration in any axon of neuromodulator-induced LTH, a phenomenon potentially important for long-lasting pain. Methiothepin does not reduce axonal LTH induced by local depolarization, so 5-HT is not required for all forms of axonal LTH. Serotonin-induced axonal LTH is expressed as reduced spike threshold and increased repetitive firing, whereas depolarization-induced LTH involves only reduced threshold. Like crush- and depolarization-induced LTH, 5-HT-induced LTH is blocked by inhibiting protein synthesis. Blockade by rapamycin, which also blocks synaptic LTF, is interesting because the eukaryotic protein kinase that is the target of rapamycin (TOR) has a conserved role in promoting growth by stimulating translation of proteins required for translation. Rapamycin sensitivity suggests that localized increases in translation of proteins that promote axonal conduction and excitability at sites of nerve injury may be regulated by the same signals that increase translation of proteins that promote neuronal growth.

Motor axon excitability during Wallerian degeneration

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Moldovan, Mihai; Alvarez, Susana; Krarup, Christian

2008-01-01

Axonal loss and degeneration are major factors in determining long-term outcome in patients with peripheral nerve disorders or injury. Following loss of axonal continuity, the isolated nerve stump distal to the lesion undergoes Wallerian degeneration in several phases. In the initial 'latent' phase......, action potential propagation and structural integrity of the distal segment are maintained. The aim of this study was to investigate in vivo the changes in membrane function of motor axons during the 'latent' phase of Wallerian degeneration. Multiple indices of axonal excitability of the tibial nerve...

Chronic ethanol intake induces partial microglial activation that is not reversed by long-term ethanol withdrawal in the rat hippocampal formation.

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Cruz, Catarina; Meireles, Manuela; Silva, Susana M

2017-05-01

Neuroinflammation has been implicated in the pathogenesis of several disorders. Activation of microglia leads to the release of pro-inflammatory mediators and microglial-mediated neuroinflammation has been proposed as one of the alcohol-induced neuropathological mechanisms. The present study aimed to examine the effect of chronic ethanol exposure and long-term withdrawal on microglial activation and neuroinflammation in the hippocampal formation. Male rats were submitted to 6 months of ethanol treatment followed by a 2-month withdrawal period. Stereological methods were applied to estimate the total number of microglia and activated microglia detected by CD11b immunohistochemistry in the hippocampal formation. The expression levels of the pro-inflammatory cytokines TNF-α, COX-2 and IL-15 were measured by qRT-PCR. Alcohol consumption was associated with an increase in the total number of activated microglia but morphological assessment indicated that microglia did not exhibit a full activation phenotype. These data were supported by functional evidence since chronic alcohol consumption produced no changes in the expression of TNF-α or COX-2. The levels of IL-15 a cytokine whose expression is increased upon activation of both astrocytes and microglia, was induced by chronic alcohol treatment. Importantly, the partial activation of microglia induced by ethanol was not reversed by long-term withdrawal. This study suggests that chronic alcohol exposure induces a microglial phenotype consistent with partial activation without significant increase in classical cytokine markers of neuroinflammation in the hippocampal formation. Furthermore, long-term cessation of alcohol intake is not sufficient to alter the microglial partial activation phenotype induced by ethanol. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of a Y-tube conduit after facial nerve injury reduces collateral axonal branching at the lesion site but neither reduces polyinnervation of motor endplates nor improves functional recovery.

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Hizay, Arzu; Ozsoy, Umut; Demirel, Bahadir Murat; Ozsoy, Ozlem; Angelova, Srebrina K; Ankerne, Janina; Sarikcioglu, Sureyya Bilmen; Dunlop, Sarah A; Angelov, Doychin N; Sarikcioglu, Levent

2012-06-01

Despite increased understanding of peripheral nerve regeneration, functional recovery after surgical repair remains disappointing. A major contributing factor is the extensive collateral branching at the lesion site, which leads to inaccurate axonal navigation and aberrant reinnervation of targets. To determine whether the Y tube reconstruction improved axonal regrowth and whether this was associated with improved function. We used a Y-tube conduit with the aim of improving navigation of regenerating axons after facial nerve transection in rats. Retrograde labeling from the zygomatic and buccal branches showed a halving in the number of double-labeled facial motor neurons (15% vs 8%; P facial-facial anastomosis coaptation. However, in both surgical groups, the proportion of polyinnervated motor endplates was similar (≈ 30%; P > .05), and video-based motion analysis of whisking revealed similarly poor function. Although Y-tube reconstruction decreases axonal branching at the lesion site and improves axonal navigation compared with facial-facial anastomosis coaptation, it fails to promote monoinnervation of motor endplates and confers no functional benefit.

Epigallocatechin gallate protects dopaminergic neurons against 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity by inhibiting microglial cell activation.

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Li, Rui; Peng, Ning; Du, Fang; Li, Xu-ping; Le, Wei-dong

2006-04-01

To observe whether the dopaminergic neuroprotective effect of (-)-epigallocatechin gallate (EGCG) is associated with its inhibition of microglial cell activation in vivo. The effects of EGCG at different doses on dopaminergic neuronal survival were tested in a methyl-4-phenyl-pyridinium (MPP+)-induced dopaminergic neuronal injury model in the primary mesencephalic cell cultures. With unbiased stereological method, tyrosine hydroxylase-immunoreactive (TH-ir) cells were counted in the A8, A9 and A10 regions of the substantia nigra (SN) in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated C57BL/6 mice. The effect of EGCG on microglial activation in the SN was also investigated. Pretreatment with EGCG (1 to 100 micromol/L) significantly attenuated MPP+-induced TH-ir cell loss by 22.2% to 80.5% in the mesencephalic cell cultures. In MPTP-treated C57BL/6 mice, EGCG at a low concentration (1 mg/kg) provided significant protection against MPTP-induced TH-ir cell loss by 50.9% in the whole nigral area and by 71.7% in the A9 region. EGCG at 5 mg/kg showed more prominent protective effect than at 1 or 10 mg/kg. EGCG pretreatment significantly inhibited microglial activation and CD11b expression induced by MPTP. EGCG exerts potent dopaminergic neuroprotective activity by means of microglial inhibition, which shed light on the potential use of EGCG in treatment of Parkinson's disease.

Experimental autoimmune prostatitis induces microglial activation in the spinal cord.

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Wong, Larry; Done, Joseph D; Schaeffer, Anthony J; Thumbikat, Praveen

2015-01-01

The pathogenesis of chronic prostatitis/chronic pelvic pain syndrome is unknown and factors including the host's immune response and the nervous system have been attributed to the development of CP/CPPS. We previously demonstrated that mast cells and chemokines such as CCL2 and CCL3 play an important role in mediating prostatitis. Here, we examined the role of neuroinflammation and microglia in the CNS in the development of chronic pelvic pain. Experimental autoimmune prostatitis (EAP) was induced using a subcutaneous injection of rat prostate antigen. Sacral spinal cord tissue (segments S14-S5) was isolated and utilized for immunofluorescence or QRT-PCR analysis. Tactile allodynia was measured at baseline and at various points during EAP using Von Frey fibers as a function for pelvic pain. EAP mice were treated with minocycline after 30 days of prostatitis to test the efficacy of microglial inhibition on pelvic pain. Prostatitis induced the expansion and activation of microglia and the development of inflammation in the spinal cord as determined by increased expression levels of CCL3, IL-1β, Iba1, and ERK1/2 phosphorylation. Microglial activation in mice with prostatitis resulted in increased expression of P2X4R and elevated levels of BDNF, two molecular markers associated with chronic pain. Pharmacological inhibition of microglia alleviated pain in mice with prostatitis and resulted in decreased expression of IL-1β, P2X4R, and BDNF. Our data show that prostatitis leads to inflammation in the spinal cord and the activation and expansion of microglia, mechanisms that may contribute to the development and maintenance of chronic pelvic pain. © 2014 Wiley Periodicals, Inc.

Dynamics of oligodendrocyte responses to anterograde axonal (Wallerian) and terminal degeneration in normal and TNF-transgenic mice

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Drøjdahl, Nina; Fenger, Christina; Nielsen, Helle H

2004-01-01

degeneration and lesion-induced axonal sprouting in the hippocampal dentate gyrus in TNF-transgenic mice with the response in genetically normal mice. Transectioning of the entorhino-dentate perforant path axonal projection increased hippocampal TNF mRNA expression in both types of mice, but to significantly...... larger levels in the TNF-transgenics. At 5 days after axonal transection, numbers of oligodendrocytes and myelin basic protein (MBP) mRNA expression in the denervated dentate gyrus in TNF-transgenic mice had increased to the same extent as in nontransgenic littermates. At this time, transgenics showed...

C3-dependent mechanism of microglial priming relevant to multiple sclerosis

NARCIS (Netherlands)

Ramaglia, Valeria; Hughes, Timothy R.; Donev, Rossen M.; Ruseva, Marieta M.; Wu, Xiaobo; Huitinga, Inge; Baas, Frank; Neal, James W.; Morgan, B. Paul

2012-01-01

Microglial priming predisposes the brain to neurodegeneration and affects disease progression. The signal to switch from the quiescent to the primed state is unknown. We show that deleting the C3 convertase regulator complement receptor 1-related protein y (Crry) induces microglial priming. Mice

Herpes simplex virus induces neural oxidative damage via microglial cell Toll-like receptor-2

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Little Morgan R

2010-06-01

Full Text Available Abstract Background Using a murine model of herpes simplex virus (HSV-1 encephalitis, our laboratory has determined that induction of proinflammatory mediators in response to viral infection is largely mediated through a Toll-like receptor-2 (TLR2-dependent mechanism. Published studies have shown that, like other inflammatory mediators, reactive oxygen species (ROS are generated during viral brain infection. It is increasingly clear that ROS are responsible for facilitating secondary tissue damage during central nervous system infection and may contribute to neurotoxicity associated with herpes encephalitis. Methods Purified microglial cell and mixed neural cell cultures were prepared from C57B/6 and TLR2-/- mice. Intracellular ROS production in cultured murine microglia was measured via 2', 7'-Dichlorofluorescin diacetate (DCFH-DA oxidation. An assay for 8-isoprostane, a marker of lipid peroxidation, was utilized to measure free radical-associated cellular damage. Mixed neural cultures obtained from β-actin promoter-luciferase transgenic mice were used to detect neurotoxicity induced by HSV-infected microglia. Results Stimulation with HSV-1 elevated intracellular ROS in wild-type microglial cell cultures, while TLR2-/- microglia displayed delayed and attenuated ROS production following viral infection. HSV-infected TLR2-/- microglia produced less neuronal oxidative damage to mixed neural cell cultures in comparison to HSV-infected wild-type microglia. Further, HSV-infected TLR2-/- microglia were found to be less cytotoxic to cultured neurons compared to HSV-infected wild-type microglia. These effects were associated with decreased activation of p38 MAPK and p42/p44 ERK in TLR2-/- mice. Conclusions These studies demonstrate the importance of microglial cell TLR2 in inducing oxidative stress and neuronal damage in response to viral infection.

Inhibitory Effects of Ketamine on Lipopolysaccharide-Induced Microglial Activation

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Yi Chang

2009-01-01

Full Text Available Microglia activated in response to brain injury release neurotoxic factors including nitric oxide (NO and proinflammatory cytokines such as tumor necrosis factor-α (TNF-α and interleukin-1β (IL-1β. Ketamine, an anesthetic induction agent, is generally reserved for use in patients with severe hypotension or respiratory depression. In this study, we found that ketamine (100 and 250 μM concentration-dependently inhibited lipopolysaccharide (LPS-induced NO and IL-1β release in primary cultured microglia. However, ketamine (100 and 250 μM did not significantly inhibit the LPS-induced TNF-α production in microglia, except at the higher concentration (500 μM. Further study of the molecular mechanisms revealed that ketamine markedly inhibited extracellular signal-regulated kinase (ERK1/2 phosphorylation but not c-Jun N-terminal kinase or p38 mitogen-activated protein kinase stimulated by LPS in microglia. These results suggest that microglial inactivation by ketamine is at least partially due to inhibition of ERK1/2 phosphorylation.

Curcumin is a potent modulator of microglial gene expression and migration

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Aslanidis Alexander

2011-09-01

Full Text Available Abstract Background Microglial cells are important effectors of the neuronal innate immune system with a major role in chronic neurodegenerative diseases. Curcumin, a major component of tumeric, alleviates pro-inflammatory activities of these cells by inhibiting nuclear factor kappa B (NFkB signaling. To study the immuno-modulatory effects of curcumin on a transcriptomic level, DNA-microarray analyses were performed with resting and LPS-challenged microglial cells after short-term treatment with curcumin. Methods Resting and LPS-activated BV-2 cells were stimulated with curcumin and genome-wide mRNA expression patterns were determined using DNA-microarrays. Selected qRT-PCR analyses were performed to confirm newly identified curcumin-regulated genes. The migration potential of microglial cells was determined with wound healing assays and transwell migration assays. Microglial neurotoxicity was estimated by morphological analyses and quantification of caspase 3/7 levels in 661W photoreceptors cultured in the presence of microglia-conditioned medium. Results Curcumin treatment markedly changed the microglial transcriptome with 49 differentially expressed transcripts in a combined analysis of resting and activated microglial cells. Curcumin effectively triggered anti-inflammatory signals as shown by induced expression of Interleukin 4 and Peroxisome proliferator activated receptor α. Several novel curcumin-induced genes including Netrin G1, Delta-like 1, Platelet endothelial cell adhesion molecule 1, and Plasma cell endoplasmic reticulum protein 1, have been previously associated with adhesion and cell migration. Consequently, curcumin treatment significantly inhibited basal and activation-induced migration of BV-2 microglia. Curcumin also potently blocked gene expression related to pro-inflammatory activation of resting cells including Toll-like receptor 2 and Prostaglandin-endoperoxide synthase 2. Moreover, transcription of NO synthase 2 and

Curcumin is a potent modulator of microglial gene expression and migration

Science.gov (United States)

2011-01-01

Background Microglial cells are important effectors of the neuronal innate immune system with a major role in chronic neurodegenerative diseases. Curcumin, a major component of tumeric, alleviates pro-inflammatory activities of these cells by inhibiting nuclear factor kappa B (NFkB) signaling. To study the immuno-modulatory effects of curcumin on a transcriptomic level, DNA-microarray analyses were performed with resting and LPS-challenged microglial cells after short-term treatment with curcumin. Methods Resting and LPS-activated BV-2 cells were stimulated with curcumin and genome-wide mRNA expression patterns were determined using DNA-microarrays. Selected qRT-PCR analyses were performed to confirm newly identified curcumin-regulated genes. The migration potential of microglial cells was determined with wound healing assays and transwell migration assays. Microglial neurotoxicity was estimated by morphological analyses and quantification of caspase 3/7 levels in 661W photoreceptors cultured in the presence of microglia-conditioned medium. Results Curcumin treatment markedly changed the microglial transcriptome with 49 differentially expressed transcripts in a combined analysis of resting and activated microglial cells. Curcumin effectively triggered anti-inflammatory signals as shown by induced expression of Interleukin 4 and Peroxisome proliferator activated receptor α. Several novel curcumin-induced genes including Netrin G1, Delta-like 1, Platelet endothelial cell adhesion molecule 1, and Plasma cell endoplasmic reticulum protein 1, have been previously associated with adhesion and cell migration. Consequently, curcumin treatment significantly inhibited basal and activation-induced migration of BV-2 microglia. Curcumin also potently blocked gene expression related to pro-inflammatory activation of resting cells including Toll-like receptor 2 and Prostaglandin-endoperoxide synthase 2. Moreover, transcription of NO synthase 2 and Signal transducer and activator

Peripheral nerve injury induces glial activation in primary motor cortex

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Julieta Troncoso

2015-02-01

Full Text Available Preliminary evidence suggests that peripheral facial nerve injuries are associated with sensorimotor cortex reorganization. We have characterized facial nerve lesion-induced structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with glial cell density using a rodent facial paralysis model. First, we used adult transgenic mice expressing green fluorescent protein in microglia and yellow fluorescent protein in pyramidal neurons which were subjected to either unilateral lesion of the facial nerve or sham surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1. It was found that facial nerve lesion induced long-lasting changes in dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Pyramidal cells’ dendritic arborization underwent overall shrinkage and transient spine pruning. Moreover, microglial cell density surrounding vM1 layer 5 pyramidal neurons was significantly increased with morphological bias towards the activated phenotype. Additionally, we induced facial nerve lesion in Wistar rats to evaluate the degree and extension of facial nerve lesion-induced reorganization processes in central nervous system using neuronal and glial markers. Immunoreactivity to NeuN (neuronal nuclei antigen, GAP-43 (growth-associated protein 43, GFAP (glial fibrillary acidic protein, and Iba 1 (Ionized calcium binding adaptor molecule 1 were evaluated 1, 3, 7, 14, 28 and 35 days after either unilateral facial nerve lesion or sham surgery. Patches of decreased NeuN immunoreactivity were found bilaterally in vM1 as well as in primary somatosensory cortex (CxS1. Significantly increased GAP-43 immunoreactivity was found bilaterally after the lesion in hippocampus, striatum, and sensorimotor cortex. One day after lesion GFAP immunoreactivity increased bilaterally in hippocampus, subcortical white

Microglial Cells Prevent Hemorrhage in Neonatal Focal Arterial Stroke.

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Fernández-López, David; Faustino, Joel; Klibanov, Alexander L; Derugin, Nikita; Blanchard, Elodie; Simon, Franziska; Leib, Stephen L; Vexler, Zinaida S

2016-03-09

Perinatal stroke leads to significant morbidity and long-term neurological and cognitive deficits. The pathophysiological mechanisms of brain damage depend on brain maturation at the time of stroke. To understand whether microglial cells limit injury after neonatal stroke by preserving neurovascular integrity, we subjected postnatal day 7 (P7) rats depleted of microglial cells, rats with inhibited microglial TGFbr2/ALK5 signaling, and corresponding controls, to transient middle cerebral artery occlusion (tMCAO). Microglial depletion by intracerebral injection of liposome-encapsulated clodronate at P5 significantly reduced vessel coverage and triggered hemorrhages in injured regions 24 h after tMCAO. Lack of microglia did not alter expression or intracellular redistribution of several tight junction proteins, did not affect degradation of collagen IV induced by the tMCAO, but altered cell types producing TGFβ1 and the phosphorylation and intracellular distribution of SMAD2/3. Selective inhibition of TGFbr2/ALK5 signaling in microglia via intracerebral liposome-encapsulated SB-431542 delivery triggered hemorrhages after tMCAO, demonstrating that TGFβ1/TGFbr2/ALK5 signaling in microglia protects from hemorrhages. Consistent with observations in neonatal rats, depletion of microglia before tMCAO in P9 Cx3cr1(GFP/+)/Ccr2(RFP/+) mice exacerbated injury and induced hemorrhages at 24 h. The effects were independent of infiltration of Ccr2(RFP/+) monocytes into injured regions. Cumulatively, in two species, we show that microglial cells protect neonatal brain from hemorrhage after acute ischemic stroke. Copyright © 2016 the authors 0270-6474/16/362881-13$15.00/0.

Mitochondrial Dynamics Decrease Prior to Axon Degeneration Induced by Vincristine and are Partially Rescued by Overexpressed cytNmnat1.

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Gregory Berbusse

2016-07-01

Full Text Available Axon degeneration is a prominent feature of various neurodegenerative diseases, such as Parkinson’s and Alzheimer’s, and is often characterized by aberrant mitochondrial dynamics. Mitochondrial fission, fusion, and motility have been shown to be particularly important in progressive neurodegeneration. Thus we investigated these imperative dynamics, as well as mitochondrial fragmentation in vincristine induced axon degradation in cultured DRG neurons. CytNmnat1 inhibits axon degeneration in various paradigms including vincristine toxicity. The mechanism of its protection is not yet fully understood; therefore, we also investigated the effect of cytNmnat1 on mitochondrial dynamics in vincristine treated neurons. We observed that vincristine treatment decreases the rate of mitochondrial fission, fusion and motility and induces mitochondrial fragmentation. These mitochondrial events precede visible axon degeneration. Overexpression of cytNmnat1 inhibits axon degeneration and preserves the normal mitochondrial dynamics and motility in vincristine treated neurons. We suggest the alterations in mitochondrial structure and dynamics are early events which lead to axon degeneration and cytNmnat1 blocks axon degeneration by halting the vincristine induced changes to mitochondrial structure and dynamics.

DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration.

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Kaselis, Andrius; Treinys, Rimantas; Vosyliūtė, Rūta; Šatkauskas, Saulius

2014-03-01

Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

Increased microglial catalase activity in multiple sclerosis grey matter.

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Gray, Elizabeth; Kemp, Kevin; Hares, Kelly; Redondo, Julianna; Rice, Claire; Scolding, Neil; Wilkins, Alastair

2014-04-22

Chronic demyelination, on-going inflammation, axonal loss and grey matter neuronal injury are likely pathological processes that contribute to disease progression in multiple sclerosis (MS). Although the precise contribution of each process and their aetiological substrates is not fully known, recent evidence has implicated oxidative damage as a major cause of tissue injury in MS. The degree of tissue injury caused by oxidative molecules, such as reactive oxygen species (ROS), is balanced by endogenous anti-oxidant enzymes which detoxify ROS. Understanding endogenous mechanisms which protect the brain against oxidative injury in MS is important, since enhancing anti-oxidant responses is a major therapeutic strategy for preventing irreversible tissue injury in the disease. Our aims were to determine expression and activity levels of the hydrogen peroxide-reducing enzyme catalase in MS grey matter (GM). In MS GM, a catalase enzyme activity was elevated compared to control GM. We measured catalase protein expression by immune dot-blotting and catalase mRNA by a real-time polymerase chain reaction (RT-PCR). Protein analysis studies showed a strong positive correlation between catalase and microglial marker IBA-1 in MS GM. In addition, calibration of catalase mRNA level with reference to the microglial-specific transcript AIF-1 revealed an increase in this transcript in MS. This was reflected by the extent of HLA-DR immunolabeling in MS GM which was significantly elevated compared to control GM. Collectively, these observations provide evidence that microglial catalase activity is elevated in MS grey matter and may be an important endogenous anti-oxidant defence mechanism in MS. Copyright © 2014 Elsevier B.V. All rights reserved.

Developmental plasticity of ascending spinal axons studies using the North American opossum, Didelphis virginiana.

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Terman, J R; Wang, X M; Martin, G F

1999-01-11

The objectives of the present study were to determine if axons of all ascending tracts grow through the lesion after transection of the thoracic spinal cord during development in the North American opossum, and if so, whether they reach regions of the brain they normally innervate. Opossum pups were subjected to transection of the mid-thoracic cord at PD5, PD8, PD12, PD20, or PD26 and injections of Fast Blue (FB) into the lower thoracic or upper lumbar cord 30-40 days or 6 months later. In the PD5 transected cases, labeled axons were present in all of the supraspinal areas labeled by comparable injections in unlesioned, age-matched controls. In the experimental cases, however, labeled axons appeared to be fewer in number and in some areas more restricted in location than in the controls. When lesions were made at PD8, labeled axons were present in the brain of animals allowed to survive 30-40 days prior to FB injections but they were not observed in those allowed to survive 6 months. When lesions were made at PD12 or later, labeled axons were never found rostral to the lesion. It appears, therefore, that axons of all ascending spinal pathways grow though the lesion after transection of the thoracic cord in developing opossums and that they innervate appropriate areas of the brain. Interestingly, the critical period for such growth is shorter than that for most descending axons, suggesting that factors which influence loss of developmental plasticity are not the same for all axons.

The NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation

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Shi Fushan

2012-07-01

Full Text Available Abstract Background Prion diseases are neurodegenerative disorders characterized by the accumulation of an abnormal disease-associated prion protein, PrPSc. In prion-infected brains, activated microglia are often present in the vicinity of PrPSc aggregates, and microglial activation is thought to play a key role in the pathogenesis of prion diseases. Although interleukin (IL-1β release by prion-induced microglia has been widely reported, the mechanism by which primed microglia become activated and secrete IL-1β in prion diseases has not yet been elucidated. In this study, we investigated the role of the NACHT, LRR and PYD domains-containing protein (NALP3 inflammasome in IL-1β release from lipopolysaccharide (LPS-primed microglia after exposure to a synthetic neurotoxic prion fragment (PrP106-126. Methods The inflammasome components NALP3 and apoptosis-associated speck-like protein (ASC were knocked down by gene silencing. IL-1β production was assessed using ELISA. The mRNA expression of NALP3, ASC, and pro-inflammatory factors was measured by quantitative PCR. Western blot analysis was used to detect the protein level of NALP3, ASC, caspase-1 and nuclear factor-κB. Results We found that that PrP106-126-induced IL-1β release depends on NALP3 inflammasome activation, that inflammasome activation is required for the synthesis of pro-inflammatory and chemotactic factors by PrP106-126-activated microglia, that inhibition of NF-κB activation abrogated PrP106-126-induced NALP3 upregulation, and that potassium efflux and production of reactive oxygen species were implicated in PrP106-126-induced NALP3 inflammasome activation in microglia. Conclusions We conclude that the NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation. To our knowledge, this is the first time that strong evidence for the involvement of NALP3 inflammasome in prion-associated inflammation has been found.

Enhanced microglial clearance of myelin debris in T cell-infiltrated central nervous system

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Nielsen, Helle Hvilsted; Ladeby, Rune; Fenger, Christina

2009-01-01

Acute multiple sclerosis lesions are characterized by accumulation of T cells and macrophages, destruction of myelin and oligodendrocytes, and axonal damage. There is, however, limited information on neuroimmune interactions distal to sites of axonal damage in the T cell-infiltrated central nervo...

Immunohistochemical and transcriptome analyses indicate complex breakdown of axonal transport mechanisms in canine distemper leukoencephalitis.

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Spitzbarth, Ingo; Lempp, Charlotte; Kegler, Kristel; Ulrich, Reiner; Kalkuhl, Arno; Deschl, Ulrich; Baumgärtner, Wolfgang; Seehusen, Frauke

2016-07-01

CDV-DL (Canine distemper virus-induced demyelinating leukoencephalitis) represents a spontaneously occurring animal model for demyelinating disorders. Axonopathy represents a key pathomechanism in this disease; however, its underlying pathogenesis has not been addressed in detail so far. This study aimed at the characterization of axonal cytoskeletal, transport, and potential regenerative changes with a parallel focus upon Schwann cell remyelination. Immunohistochemistry of canine cerebellar tissue as well as a comparative analysis of genes from an independent microarray study were performed. Increased axonal immunoreactivity for nonphosphorylated neurofilament was followed by loss of cytoskeletal and motor proteins. Interestingly, a subset of genes encoding for neurofilament subunits and motor proteins was up-regulated in the chronic stage compared to dogs with subacute CDV-DL. However, immunohistochemically, hints for axonal regeneration were restricted to up-regulated axonal positivity of hypoxia-inducible factor 1 alpha, while growth-associated protein 43, erythropoietin and its receptor were not or even down-regulated. Periaxin-positive structures, indicative of Schwann cell remyelination, were only detected within few advanced lesions. The present findings demonstrate a complex sequence of axonal cytoskeletal breakdown mechanisms. Moreover, though sparse, this is the first report of Schwann cell remyelination in CDV-DL. Facilitation of these very limited endogenous regenerative responses represents an important topic for future research.

Deafferentation-Induced Redistribution of MMP-2, but Not of MMP-9, Depends on the Emergence of GAP-43 Positive Axons in the Adult Rat Cochlear Nucleus

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Michaela Fredrich

2011-01-01

Full Text Available The matrix metalloproteinases MMP-9 and MMP-2, major modulators of the extracellular matrix (ECM, were changed in amount and distribution in the rat anteroventral cochlear nucleus (AVCN following its sensory deafferentation by cochlear ablation. To determine what causal relationships exist between the redistribution of MMP-9 and MMP-2 and deafferentation-induced reinnervation, kainic acid was stereotaxically injected into the ventral nucleus of the trapezoid body (VNTB prior to cochlear ablation, killing cells that deliver the growth associated protein 43 (GAP-43 into AVCN. Deafferentation-induced changes in the pattern of MMP-9 staining remained unaffected by VNTB lesions. By contrast, changes in the distribution of MMP-2 normally evoked by sensory deafferentation were reversed if GAP-43 positive axons were prevented to grow in AVCN. In conclusion, GAP-43-containing axons emerging in AVCN after cochlear ablation seem to be causal for the maintenance of MMP-2-mediated ECM remodeling.

Increased synthesis of heparin affin regulatory peptide in the perforant path lesioned mouse hippocampal formation

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Poulsen, F R; Lagord, C; Courty, J

2000-01-01

differentiation in vivo. Here we have investigated the expression of HARP mRNA and protein in the perforant path lesioned C57B1/6 mouse hippocampal formation from 1 to 35 days after surgery. This type of lesion induces a dense anterograde and terminal axonal degeneration, activation of glial cells, and reactive...... axonal sprouting within the perforant path zones of the fascia dentata and hippocampus as well as axotomy-induced retrograde neuronal degeneration in the entorhinal cortex. Analysis of sham- and unoperated control mice showed that HARP mRNA is expressed in neurons and white and gray matter glial cells...... as well as vascular and pial cells throughout the normal, adult brain. Lesioning induced high levels of HARP mRNA in astroglial-like cells in the denervated zones of fascia dentata and hippocampus as soon as day 2 postlesion. This expression reached maximum at day 4, and declined toward normal at day 7...

Long-Standing Motor and Sensory Recovery following Acute Fibrin Sealant Based Neonatal Sciatic Nerve Repair

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Natalia Perussi Biscola

2016-01-01

Full Text Available Brachial plexus lesion results in loss of motor and sensory function, being more harmful in the neonate. Therefore, this study evaluated neuroprotection and regeneration after neonatal peripheral nerve coaptation with fibrin sealant. Thus, P2 neonatal Lewis rats were divided into three groups: AX: sciatic nerve axotomy (SNA without treatment; AX+FS: SNA followed by end-to-end coaptation with fibrin sealant derived from snake venom; AX+CFS: SNA followed by end-to-end coaptation with commercial fibrin sealant. Results were analyzed 4, 8, and 12 weeks after lesion. Astrogliosis, microglial reaction, and synapse preservation were evaluated by immunohistochemistry. Neuronal survival, axonal regeneration, and ultrastructural changes at ventral spinal cord were also investigated. Sensory-motor recovery was behaviorally studied. Coaptation preserved synaptic covering on lesioned motoneurons and led to neuronal survival. Reactive gliosis and microglial reaction decreased in the same groups (AX+FS, AX+CFS at 4 weeks. Regarding axonal regeneration, coaptation allowed recovery of greater number of myelinated fibers, with improved morphometric parameters. Preservation of inhibitory synaptic terminals was accompanied by significant improvement in the motor as well as in the nociceptive recovery. Overall, the present data suggest that acute repair of neonatal peripheral nerves with fibrin sealant results in neuroprotection and regeneration of motor and sensory axons.

Spinal Microgliosis Due to Resident Microglial Proliferation Is Required for Pain Hypersensitivity after Peripheral Nerve Injury

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Nan Gu

2016-07-01

Full Text Available Peripheral nerve injury causes neuropathic pain accompanied by remarkable microgliosis in the spinal cord dorsal horn. However, it is still debated whether infiltrated monocytes contribute to injury-induced expansion of the microglial population. Here, we found that spinal microgliosis predominantly results from local proliferation of resident microglia but not from infiltrating monocytes after spinal nerve transection (SNT by using two genetic mouse models (CCR2RFP/+:CX3CR1GFP/+ and CX3CR1creER/+:R26tdTomato/+ mice as well as specific staining of microglia and macrophages. Pharmacological inhibition of SNT-induced microglial proliferation correlated with attenuated neuropathic pain hypersensitivities. Microglial proliferation is partially controlled by purinergic and fractalkine signaling, as CX3CR1−/− and P2Y12−/− mice show reduced spinal microglial proliferation and neuropathic pain. These results suggest that local microglial proliferation is the sole source of spinal microgliosis, which represents a potential therapeutic target for neuropathic pain management.

Neuron-to-neuron transmission of α-synuclein fibrils through axonal transport

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Freundt, Eric C.; Maynard, Nate; Clancy, Eileen K.; Roy, Shyamali; Bousset, Luc; Sourigues, Yannick; Covert, Markus; Melki, Ronald; Kirkegaard, Karla; Brahic, Michel

2012-01-01

Objective The lesions of Parkinson's disease spread through the brain in a characteristic pattern that corresponds to axonal projections. Previous observations suggest that misfolded α-synuclein could behave as a prion, moving from neuron to neuron and causing endogenous α-synuclein to misfold. Here, we characterized and quantified the axonal transport of α-synuclein fibrils and showed that fibrils could be transferred from axons to second-order neurons following anterograde transport. Methods We grew primary cortical mouse neurons in microfluidic devices to separate soma from axonal projections in fluidically isolated microenvironments. We used live-cell imaging and immunofluorescence to characterize the transport of fluorescent α-synuclein fibrils and their transfer to second-order neurons. Results Fibrillar α-synuclein was internalized by primary neurons and transported in axons with kinetics consistent with slow component-b of axonal transport (fast axonal transport with saltatory movement). Fibrillar α-synuclein was readily observed in the cell bodies of second-order neurons following anterograde axonal transport. Axon-to-soma transfer appeared not to require synaptic contacts. Interpretation These results support the hypothesis that the progression of Parkinson's disease can be caused by neuron-to-neuron spread of α-synuclein aggregates and that the anatomical pattern of progression of lesions between axonally connected areas results from the axonal transport of such aggregates. That the transfer did not appear to be transsynaptic gives hope that α-synuclein fibrils could be intercepted by drugs during the extra-cellular phase of their journey. PMID:23109146

Mir143-BBC3 cascade reduces microglial survival via interplay between apoptosis and autophagy: Implications for methamphetamine-mediated neurotoxicity

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Zhang, Yuan; Shen, Kai; Bai, Ying; Lv, Xuan; Huang, Rongrong; Zhang, Wei; Chao, Jie; Nguyen, Lan K.; Hua, Jun; Gan, Guangming; Hu, Gang; Yao, Honghong

2016-01-01

ABSTRACT BBC3 (BCL2 binding component 3) is a known apoptosis inducer; however, its role in microglial survival remains poorly understood. In addition to the classical transcription factor TRP53, Mir143 is involved in BBC3 expression at the post-transcriptional level. Here, we identify unique roles of Mir143-BBC3 in mediating microglial survival via the regulation of the interplay between apoptosis and autophagy. Autophagy inhibition accelerated methamphetamine-induced apoptosis, whereas autophagy induction attenuated the decrease in microglial survival. Moreover, anti-Mir143-dependent BBC3 upregulation reversed the methamphetamine-induced decrease in microglial survival via the regulation of apoptosis and autophagy. The in vivo relevance of these findings was confirmed in mouse models, which demonstrated that the microinjection of anti-Mir143 into the hippocampus ameliorated the methamphetamine-induced decrease in microglia as well as that observed in heterozygous Mir143+/− mice. These findings provide new insight regarding the specific contributions of Mir143-BBC3 to microglial survival in the context of drug abuse. PMID:27464000

[Total brain T2-hyperintense lesion-volume and the axonal damage in the normal-appearing white matter of brainstem in early lapsing-remitting multiple sclerosis].

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Pascual-Lozano, A M; Martínez-Bisbal, M C; Boscá-Blasco, I; Valero-Merino, C; Coret-Ferrer, F; Martí-Bonmatí, L; Martínez-Granados, B; Celda, B; Casanova-Estruch, B

To evaluate the relationship between the total brain T2-hyperintense lesion volume (TBT2LV) and the axonal damage in the normal-appearing white matter of brainstem measured by 1H-MRS in a group of early relapsing-remitting multiple sclerosis patients. 40 relapsing-remitting multiple sclerosis patients and ten sex- and age-matched healthy subjects were prospectively studied for two years. T2-weighted MR and 1H-MRS imaging were acquired at time of recruitment and at year two. The TBT2LV was calculated with a semiautomatic program; N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) resonances areas were integrated with jMRUI program and the ratios were calculated for four volume elements that represented the brainstem. At basal study we obtained an axonal loss (as a decrement of NAA/ Cho ratio) in the group of patients compared with controls (p = 0.017); this axonal loss increased at the second year of the follow-up for patients (NAA/Cho decrease, p = 0.004, and NAA/Cr decrease, p = 0.002) meanwhile control subjects had no significant metabolic changes. Higher lesion load was correlated with a poor clinical outcome, being the correlation between the basal TBT2LV and the Expanded Disability Status Scale at second year (r = 0.299; p = 0.05). Besides, axonal loss was not homogeneous for all multiple sclerosis patients, being stronger in the subgroup of patients with high basal TBT2LV (p = 0.043; ANOVA). Our data suggest that axonal damage is early in multiple sclerosis and higher in patients high basal TBT2LV, suggesting a possible relationship between these two phenomena.

Dendrobium nobile Lindl alkaloid, a novel autophagy inducer, protects against axonal degeneration induced by Aβ25-35 in hippocampus neurons in vitro.

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Li, Li-Sheng; Lu, Yan-Liu; Nie, Jing; Xu, Yun-Yan; Zhang, Wei; Yang, Wen-Jin; Gong, Qi-Hai; Lu, Yuan-Fu; Lu, Yang; Shi, Jing-Shan

2017-04-01

Axonal degeneration is a pathological symbol in the early stage of Alzheimer's disease (AD), which can be triggered by amyloid-β (Aβ) peptide deposition. Growing evidence indicates that deficit of autophagy eventually leads to the axonal degeneration. Our previous studies have shown that Dendrobium nobile Lindl alkaloid (DNLA) had protective effect on neuron impairment in vivo and in vitro; however, the underlying mechanisms is still unclear. We exposed cultured hippocampus neurons to Aβ 25-35 to investigate the effect of DNLA in vitro. Axonal degeneration was evaluated by immunofluorescence staining and MTT assay. Neurons overexpressing GFP-LC3B were used to measure the formation of autophagosome. Autophagosome-lysosome fusion, the lysosomal pH, and cathepsin activity were assessed to reflect autophagy process. Proteins of interest were analyzed by Western blot. DNLA pretreatment significantly inhibited axonal degeneration induced by Aβ 25-35 peptide in vitro. Further studies revealed DNLA treatment increased autophagic flux through promoting formation and degradation of autophagosome in hippocampus neurons. Moreover, enhancement of autophagic flux was responsible for the protective effects of DNLA on axonal degeneration. DNLA prevents Aβ 25-35 -induced axonal degeneration via activation of autophagy process and could be a novel therapeutic target. © 2017 John Wiley & Sons Ltd.

Hirsutine, an indole alkaloid of Uncaria rhynchophylla, inhibits inflammation-mediated neurotoxicity and microglial activation.

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Jung, Hwan Yong; Nam, Kyong Nyon; Woo, Byung-Choel; Kim, Kyoo-Pil; Kim, Sung-Ok; Lee, Eunjoo H

2013-01-01

Chronic microglial activation endangers neuronal survival through the release of various pro-inflammatory and neurotoxic factors. As such, negative regulators of microglial activation have been considered as potential therapeutic candidates to reduce the risk of neurodegeneration associated with inflammation. Uncaria rhynchophylla (U. rhynchophylla) is a traditional oriental herb that has been used for treatment of disorders of the cardiovascular and central nervous systems. Hirsutine (HS), one of the major indole alkaloids of U. rhynchophylla, has demonstrated neuroprotective potential. The aim of the present study was to examine the efficacy of HS in the repression of inflammation-induced neurotoxicity and microglial cell activation. In organotypic hippocampal slice cultures, HS blocked lipopolysaccharide (LPS)-related hippocampal cell death and production of nitric oxide (NO), prostaglandin (PG) E2 and interleukin-1β. HS was demonstrated to effectively inhibit LPS-induced NO release from cultured rat brain microglia. The compound reduced the LPS-stimulated production of PGE2 and intracellular reactive oxygen species. HS significantly decreased LPS-induced phosphorylation of the mitogen-activated protein kinases and Akt signaling proteins. In conclusion, HS reduces the production of various neurotoxic factors in activated microglial cells and possesses neuroprotective activity in a model of inflammation-induced neurotoxicity.

3Tesla magnetic resonance examination of a patient suffering from diffuse axonal injury

International Nuclear Information System (INIS)

Bonchev, S.; Zlatareva, D.; Hadjidekov, V.

2016-01-01

Diffuse axonal injury has been observed in traumatic brain injury. Both type of lesions - haemorrhagic and non-haemorrhagic, demonstrate on MRI. We would like to introduce you a 24 year old outpatient man, who was examined in our Department with a past medical history of severe traumatic brain injury, followed by two weeks of coma in Intensive care, discharged from hospital with good outcome. Subsequently cognitive impairments have developed and an episode of tonic-clonic seizure have been undergone by the patient. 3Tesla MRI was performed and lesions typical for diffuse axonal injury were found. MRI is the study of choice for demonstrating the lesions of diffuse axonal injury in the acute and chronic period

Two Modes of the Axonal Interferon Response Limit Alphaherpesvirus Neuroinvasion

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Ren Song

2016-02-01

Full Text Available Infection by alphaherpesviruses, including herpes simplex virus (HSV and pseudorabies virus (PRV, typically begins at epithelial surfaces and continues into the peripheral nervous system (PNS. Inflammatory responses are induced at the infected peripheral site prior to invasion of the PNS. When the peripheral tissue is first infected, only the innervating axons are exposed to this inflammatory milieu, which includes the interferons (IFNs. The fundamental question is how do PNS cell bodies respond to these distant, potentially damaging events experienced by axons. Using compartmented cultures that physically separate neuron axons from cell bodies, we found that pretreating isolated axons with beta interferon (IFN-β or gamma interferon (IFN-γ significantly diminished the number of herpes simplex virus 1 (HSV-1 and PRV particles moving in axons toward the cell bodies in a receptor-dependent manner. Exposing axons to IFN-β induced STAT1 phosphorylation (p-STAT1 only in axons, while exposure of axons to IFN-γ induced p-STAT1 accumulation in distant cell body nuclei. Blocking transcription in cell bodies eliminated antiviral effects induced by IFN-γ, but not those induced by IFN-β. Proteomic analysis of IFN-β- or IFN-γ-treated axons identified several differentially regulated proteins. Therefore, unlike treatment with IFN-γ, IFN-β induces a noncanonical, local antiviral response in axons. The activation of a local IFN response in axons represents a new paradigm for cytokine control of neuroinvasion.

Increased synthesis of heparin affin regulatory peptide in the perforant path lesioned mouse hippocampal formation

DEFF Research Database (Denmark)

Poulsen, F R; Lagord, C; Courty, J

2000-01-01

Heparin affin regulatory peptide (HARP), also known as pleiotrophin or heparin-binding growth-associated molecule, is a developmentally regulated extracellular matrix protein that induces cell proliferation and promotes neurite outgrowth in vitro as well as pre- and postsynaptic developmental...... differentiation in vivo. Here we have investigated the expression of HARP mRNA and protein in the perforant path lesioned C57B1/6 mouse hippocampal formation from 1 to 35 days after surgery. This type of lesion induces a dense anterograde and terminal axonal degeneration, activation of glial cells, and reactive...... axonal sprouting within the perforant path zones of the fascia dentata and hippocampus as well as axotomy-induced retrograde neuronal degeneration in the entorhinal cortex. Analysis of sham- and unoperated control mice showed that HARP mRNA is expressed in neurons and white and gray matter glial cells...

Hypoglossal-facial anastomosis (HFA) over a 10 mm gap bridged by a Y-tube-conduit enhances neurite regrowth and reduces collateral axonal branching at the lesion site.

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Ozsoy, Umut; Demirel, Bahadir Murat; Hizay, Arzu; Ozsoy, Ozlem; Ankerne, Janina; Angelova, Srebrina; Sarikcioglu, Levent; Ucar, Yasar; Angelov, Doychin N

2011-01-01

The outcome of severe peripheral nerve injuries requiring surgical repair (transection and suture) is usually poor. Recent work suggests that direct suture of nerves increases collagen production and provides unfavourable conditions for a proper axonal regrowth. We tested whether entubulation of the hypoglossal nerve into a Y-tube conduit connecting it with the zygomatic and buccal facial nerve branches would improve axonal pathfinding at the lesion site, quality of muscle reinnervation and recovery of vibrissal whisking. For hypoglossal-facial anastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of the hypoglossal nerve was entubulated and sutured into the long arm of a Y-tube (isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facial branches were entubulated and sutured to the short arms of the Y-tube. Restoration of vibrissal motor performance, degree of collateral axonal branching at the lesion site and quality of neuro-muscular junction (NMJ) reinnervation were compared to animals receiving HFA-Coaptation (no entubulation) after 4 months. HFA-Y-tube reduced collateral axonal branching. However it failed to reduce the proportion of polyinnervated NMJ and did not improve functional outcome when compared to HFA-Coaptation. Elimination of compression by tightly opposed nerve fragments improved axonal pathfinding. However, biometric analysis of vibrissae movements did not show positive effects suggesting that polyneuronal reinnervation - rather than collateral branching - may be the critical limiting factor. Since polyinnervation of muscle fibers is activity-dependent and can be manipulated, the present findings raise hopes that clinically feasible and effective therapies after HFA could be soon designed and tested.

HIV-1 Myristoylated Nef Treatment of Murine Microglial Cells Activates Inducible Nitric Oxide Synthase, NO2 Production and Neurotoxic Activity.

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Giorgio Mangino

Full Text Available The potential role of the human immunodeficiency virus-1 (HIV-1 accessory protein Nef in the pathogenesis of neuroAIDS is still poorly understood. Nef is a molecular adapter that influences several cellular signal transduction events and membrane trafficking. In human macrophages, Nef expression induces the production of extracellular factors (e.g. pro-inflammatory chemokines and cytokines and the recruitment of T cells, thus favoring their infection and its own transfer to uninfected cells via exosomes, cellular protrusions or cell-to-cell contacts. Murine cells are normally not permissive for HIV-1 but, in transgenic mice, Nef is a major disease determinant. Both in human and murine macrophages, myristoylated Nef (myr+Nef treatment has been shown to activate NF-κB, MAP kinases and interferon responsive factor 3 (IRF-3, thereby inducing tyrosine phosphorylation of signal transducers and activator of transcription (STAT-1, STAT-2 and STAT-3 through the production of proinflammatory factors.We report that treatment of BV-2 murine microglial cells with myr+Nef leads to STAT-1, -2 and -3 tyrosine phosphorylation and upregulates the expression of inducible nitric oxide synthase (iNOS with production of nitric oxide. We provide evidence that extracellular Nef regulates iNOS expression through NF-κB activation and, at least in part, interferon-β (IFNβ release that acts in concert with Nef. All of these effects require both myristoylation and a highly conserved acidic cluster in the viral protein. Finally, we report that Nef induces the release of neurotoxic factors in the supernatants of microglial cells.These results suggest a potential role of extracellular Nef in promoting neuronal injury in the murine model. They also indicate a possible interplay between Nef and host factors in the pathogenesis of neuroAIDS through the production of reactive nitrogen species in microglial cells.

Axonal transport and axon sprouting in the adult rat dentate gyrus: an autoradiographic study

International Nuclear Information System (INIS)

Goldowitz, D.; Cotman, C.W.

1980-01-01

In response to an entorhinal lesion, the commissural and associational afferents to the dentate gyrus have been shown to expand beyond their normal terminal zone into the area denervated by the entorhinal lesion. The present study has investigated the axonal transport of [ 3 H]-labeled proteins in the commissural and associational projections following an entorhinal lesion. Injections of [ 3 H]proline, [ 3 H]leucine or [ 3 H)fucose were given in the vicinity of the commissural and associational cells of origin before, immediately subsequent to, or at 5 to 15 days after the entorhinal lesion. The disposition of previously- or newly-synthesized proteins was examined in the commissural and associational terminal field at different times after an entorhinal lesion by light-microscopic autoradiography. (author)

Axonal transport and axon sprouting in the adult rat dentate gyrus: an autoradiographic study

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Goldowitz, D; Cotman, C W [California Univ., Irvine (USA)

1980-12-01

In response to an entorhinal lesion, the commissural and associational afferents to the dentate gyrus have been shown to expand beyond their normal terminal zone into the area denervated by the entorhinal lesion. The present study has investigated the axonal transport of (/sup 3/H)-labeled proteins in the commissural and associational projections following an entorhinal lesion. Injections of (/sup 3/H)proline, (/sup 3/H)leucine or (/sup 3/H)fucose were given in the vicinity of the commissural and associational cells of origin before, immediately subsequent to, or at 5 to 15 days after the entorhinal lesion. The disposition of previously- or newly-synthesized proteins was examined in the commissural and associational terminal field at different times after an entorhinal lesion by light-microscopic autoradiography.

Regulated viral BDNF delivery in combination with Schwann cells promotes axonal regeneration through capillary alginate hydrogels after spinal cord injury.

Science.gov (United States)

Liu, Shengwen; Sandner, Beatrice; Schackel, Thomas; Nicholson, LaShae; Chtarto, Abdelwahed; Tenenbaum, Liliane; Puttagunta, Radhika; Müller, Rainer; Weidner, Norbert; Blesch, Armin

2017-09-15

Grafting of cell-seeded alginate capillary hydrogels into a spinal cord lesion site provides an axonal bridge while physically directing regenerating axonal growth in a linear pattern. However, without an additional growth stimulus, bridging axons fail to extend into the distal host spinal cord. Here we examined whether a combinatory strategy would support regeneration of descending axons across a cervical (C5) lateral hemisection lesion in the rat spinal cord. Following spinal cord transections, Schwann cell (SC)-seeded alginate hydrogels were grafted to the lesion site and AAV5 expressing brain-derived neurotrophic factor (BDNF) under control of a tetracycline-regulated promoter was injected caudally. In addition, we examined whether SC injection into the caudal spinal parenchyma would further enhance regeneration of descending axons to re-enter the host spinal cord. Our data show that both serotonergic and descending axons traced by biotinylated dextran amine (BDA) extend throughout the scaffolds. The number of regenerating axons is significantly increased when caudal BDNF expression is activated and transient BDNF delivery is able to sustain axons after gene expression is switched off. Descending axons are confined to the caudal graft/host interface even with continuous BDNF expression for 8weeks. Only with a caudal injection of SCs, a pathway facilitating axonal regeneration through the host/graft interface is generated allowing axons to successfully re-enter the caudal spinal cord. Recovery from spinal cord injury is poor due to the limited regeneration observed in the adult mammalian central nervous system. Biomaterials, cell transplantation and growth factors that can guide axons across a lesion site, provide a cellular substrate, stimulate axon growth and have shown some promise in increasing the growth distance of regenerating axons. In the present study, we combined an alginate biomaterial with linear channels with transplantation of Schwann cells within

Minocycline Transiently Reduces Microglia/Macrophage Activation but Exacerbates Cognitive Deficits Following Repetitive Traumatic Brain Injury in the Neonatal Rat

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Hanlon, Lauren A.; Huh, Jimmy W.

2016-01-01

Elevated microglial/macrophage-associated biomarkers in the cerebrospinal fluid of infant victims of abusive head trauma (AHT) suggest that these cells play a role in the pathophysiology of the injury. In a model of AHT in 11-day-old rats, 3 impacts (24 hours apart) resulted in spatial learning and memory deficits and increased brain microglial/macrophage reactivity, traumatic axonal injury, neuronal degeneration, and cortical and white-matter atrophy. The antibiotic minocycline has been effective in decreasing injury-induced microglial/macrophage activation while simultaneously attenuating cellular and functional deficits in models of neonatal hypoxic ischemia, but the potential for this compound to rescue deficits after impact-based trauma to the immature brain remains unexplored. Acute minocycline administration in this model of AHT decreased microglial/macrophage reactivity in the corpus callosum of brain-injured animals at 3 days postinjury, but this effect was lost by 7 days postinjury. Additionally, minocycline treatment had no effect on traumatic axonal injury, neurodegeneration, tissue atrophy, or spatial learning deficits. Interestingly, minocycline-treated animals demonstrated exacerbated injury-induced spatial memory deficits. These results contrast with previous findings in other models of brain injury and suggest that minocycline is ineffective in reducing microglial/macrophage activation and ameliorating injury-induced deficits following repetitive neonatal traumatic brain injury. PMID:26825312

Depolarization and electrical stimulation enhance in vitro and in vivo sensory axon growth after spinal cord injury.

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Goganau, Ioana; Sandner, Beatrice; Weidner, Norbert; Fouad, Karim; Blesch, Armin

2018-02-01

Activity dependent plasticity is a key mechanism for the central nervous system (CNS) to adapt to its environment. Whether neuronal activity also influences axonal regeneration in the injured CNS, and whether electrical stimulation (ES) can activate regenerative programs in the injured CNS remains incompletely understood. Using KCl-induced depolarization, in vivo ES followed by ex-vivo neurite growth assays and ES after spinal cord lesions and cell grafting, we aimed to identify parameters important for ES-enhanced neurite growth and axonal regeneration. Using cultures of sensory neurons, neurite growth was analyzed after KCl-induced depolarization for 1-72h. Increased neurite growth was detected after short-term stimulation and after longer stimulation if a sufficient delay between stimulation and growth measurements was provided. After in vivo ES (20Hz, 2× motor threshold, 0.2ms, 1h) of the intact sciatic nerve in adult Fischer344 rats, sensory neurons showed a 2-fold increase in in vitro neurite length one week later compared to sham animals, an effect not observed one day after ES. Longer ES (7h) and repeated ES (7days, 1h each) also increased growth by 56-67% one week later, but provided no additional benefit. In vivo growth of dorsal column sensory axons into a graft of bone marrow stromal cells 4weeks after a cervical spinal cord lesion was also enhanced with a single post-injury 1h ES of the intact sciatic nerve and was also observed after repeated ES without inducing pain-like behavior. While ES did not result in sensory functional recovery, our data indicate that ES has time-dependent influences on the regenerative capacity of sensory neurons and might further enhance axonal regeneration in combinatorial approaches after SCI. Copyright © 2017 Elsevier Inc. All rights reserved.

Interaction of HmC1q with leech microglial cells: involvement of C1qBP-related molecule in the induction of cell chemotaxis

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Tahtouh Muriel

2012-02-01

Full Text Available Abstract Background In invertebrates, the medicinal leech is considered to be an interesting and appropriate model to study neuroimmune mechanisms. Indeed, this non-vertebrate animal can restore normal function of its central nervous system (CNS after injury. Microglia accumulation at the damage site has been shown to be required for axon sprouting and for efficient regeneration. We characterized HmC1q as a novel chemotactic factor for leech microglial cell recruitment. In mammals, a C1q-binding protein (C1qBP alias gC1qR, which interacts with the globular head of C1q, has been reported to participate in C1q-mediated chemotaxis of blood immune cells. In this study, we evaluated the chemotactic activities of a recombinant form of HmC1q and its interaction with a newly characterized leech C1qBP that acts as its potential ligand. Methods Recombinant HmC1q (rHmC1q was produced in the yeast Pichia pastoris. Chemotaxis assays were performed to investigate rHmC1q-dependent microglia migration. The involvement of a C1qBP-related molecule in this chemotaxis mechanism was assessed by flow cytometry and with affinity purification experiments. The cellular localization of C1qBP mRNA and protein in leech was investigated using immunohistochemistry and in situ hybridization techniques. Results rHmC1q-stimulated microglia migrate in a dose-dependent manner. This rHmC1q-induced chemotaxis was reduced when cells were preincubated with either anti-HmC1q or anti-human C1qBP antibodies. A C1qBP-related molecule was characterized in leech microglia. Conclusions A previous study showed that recruitment of microglia is observed after HmC1q release at the cut end of axons. Here, we demonstrate that rHmC1q-dependent chemotaxis might be driven via a HmC1q-binding protein located on the microglial cell surface. Taken together, these results highlight the importance of the interaction between C1q and C1qBP in microglial activation leading to nerve repair in the medicinal

Interaction of HmC1q with leech microglial cells: involvement of C1qBP-related molecule in the induction of cell chemotaxis.

Science.gov (United States)

Tahtouh, Muriel; Garçon-Bocquet, Annelise; Croq, Françoise; Vizioli, Jacopo; Sautière, Pierre-Eric; Van Camp, Christelle; Salzet, Michel; Nagnan-le Meillour, Patricia; Pestel, Joël; Lefebvre, Christophe

2012-02-22

In invertebrates, the medicinal leech is considered to be an interesting and appropriate model to study neuroimmune mechanisms. Indeed, this non-vertebrate animal can restore normal function of its central nervous system (CNS) after injury. Microglia accumulation at the damage site has been shown to be required for axon sprouting and for efficient regeneration. We characterized HmC1q as a novel chemotactic factor for leech microglial cell recruitment. In mammals, a C1q-binding protein (C1qBP alias gC1qR), which interacts with the globular head of C1q, has been reported to participate in C1q-mediated chemotaxis of blood immune cells. In this study, we evaluated the chemotactic activities of a recombinant form of HmC1q and its interaction with a newly characterized leech C1qBP that acts as its potential ligand. Recombinant HmC1q (rHmC1q) was produced in the yeast Pichia pastoris. Chemotaxis assays were performed to investigate rHmC1q-dependent microglia migration. The involvement of a C1qBP-related molecule in this chemotaxis mechanism was assessed by flow cytometry and with affinity purification experiments. The cellular localization of C1qBP mRNA and protein in leech was investigated using immunohistochemistry and in situ hybridization techniques. rHmC1q-stimulated microglia migrate in a dose-dependent manner. This rHmC1q-induced chemotaxis was reduced when cells were preincubated with either anti-HmC1q or anti-human C1qBP antibodies. A C1qBP-related molecule was characterized in leech microglia. A previous study showed that recruitment of microglia is observed after HmC1q release at the cut end of axons. Here, we demonstrate that rHmC1q-dependent chemotaxis might be driven via a HmC1q-binding protein located on the microglial cell surface. Taken together, these results highlight the importance of the interaction between C1q and C1qBP in microglial activation leading to nerve repair in the medicinal leech.

Subacute ethanol consumption reverses p-xylene-induced decreases in axonal transport

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Padilla, S.; Lyerly, D.L.; Pope, C.N.

1992-01-01

Organic solvants, as a class, have been implicated as neurotoxic agents in humans and laboratory animals. The study was designed to assess the interaction between subacute ingestion of moderate levels of ethanol and the p-xylene-induced decreases in protein and glycoprotein synthesis and axonal transport in the rat optic system. The results indicated that animals maintained on 10% ethanol as a drinking liquid show less p-xylene-induced neurotoxicity than animals receiving no ethanol supplement.

The toll-like receptor 2 agonist Pam3CSK4 is neuroprotective after spinal cord injury.

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Stivers, Nicole S; Pelisch, Nicolas; Orem, Ben C; Williams, Joshua; Nally, Jacqueline M; Stirling, David P

2017-08-01

Microglia/macrophage activation and recruitment following spinal cord injury (SCI) is associated with both detrimental and reparative functions. Stimulation of the innate immune receptor Toll-like receptor-2 (TLR2) has shown to be beneficial following SCI, and it increases axonal regeneration following optic nerve crush. However, the mechanism(s) remain unclear. As microglia express high levels of TLR2, we hypothesized that modulating the microglial response to injury using a specific TLR2 agonist, Pam3CSK4, would prevent secondary-mediated white matter degeneration following SCI. To test this hypothesis, we documented acute changes in microglia, axons, and oligodendroglia over time using two-photon excitation and an ex vivo laser-induced SCI (LiSCI) model. We utilized double transgenic mice that express GFP in either microglia or oligodendroglia, and YFP in axons, and we applied the lipophilic fluorescent dye (Nile Red) to visualize myelin. We found that treatment with Pam3CSK4 initiated one hour after injury induced a significant increase in the extent and timing of the microglial response to injury compared to vehicle controls. This enhanced response was observed 2 to 4h following SCI and was most prominent in areas closer to the ablation site. In addition, Pam3CSK4 treatment significantly reduced axonal dieback rostral and caudal to the ablation at 6h post-SCI. This protective effect of Pam3CSK4 was also mirrored when assessing secondary bystander axonal damage (i.e., axons spared by the primary injury that then succumb to secondary degeneration), and when assessing the survival of oligodendroglia. Following these imaging experiments, custom microarray analysis of the ex vivo spinal cord preparations revealed that Pam3CSK4-treatment induced an alternative (mixed M1:M2) microglial activation profile. In summary, our data suggest that by providing a second "sterile" activation signal to microglia through TLR2/TLR1 signaling, the microglial response to injury can

[Peripheral facial nerve lesion induced long-term dendritic retraction in pyramidal cortico-facial neurons].

Science.gov (United States)

Urrego, Diana; Múnera, Alejandro; Troncoso, Julieta

2011-01-01

Little evidence is available concerning the morphological modifications of motor cortex neurons associated with peripheral nerve injuries, and the consequences of those injuries on post lesion functional recovery. Dendritic branching of cortico-facial neurons was characterized with respect to the effects of irreversible facial nerve injury. Twenty-four adult male rats were distributed into four groups: sham (no lesion surgery), and dendritic assessment at 1, 3 and 5 weeks post surgery. Eighteen lesion animals underwent surgical transection of the mandibular and buccal branches of the facial nerve. Dendritic branching was examined by contralateral primary motor cortex slices stained with the Golgi-Cox technique. Layer V pyramidal (cortico-facial) neurons from sham and injured animals were reconstructed and their dendritic branching was compared using Sholl analysis. Animals with facial nerve lesions displayed persistent vibrissal paralysis throughout the five week observation period. Compared with control animal neurons, cortico-facial pyramidal neurons of surgically injured animals displayed shrinkage of their dendritic branches at statistically significant levels. This shrinkage persisted for at least five weeks after facial nerve injury. Irreversible facial motoneuron axonal damage induced persistent dendritic arborization shrinkage in contralateral cortico-facial neurons. This morphological reorganization may be the physiological basis of functional sequelae observed in peripheral facial palsy patients.

Anti-inflammatory effects of rhynchophylline and isorhynchophylline in mouse N9 microglial cells and the molecular mechanism.

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Yuan, Dan; Ma, Bin; Yang, Jing-yu; Xie, Yuan-yuan; Wang, Li; Zhang, Li-jia; Kano, Yoshihiro; Wu, Chun-fu

2009-12-01

Excessive production of nitric oxide (NO) and proinflammatory cytokines from activated microglia contributes to human neurodegenerative disorders. Our previous study demonstrated the potent inhibition of lipopolysaccharide (LPS)-induced NO production in rat primary microglial cells by rhynchophylline (RIN) and isorhynchophylline (IRN), a pair of isomeric alkaloids of Uncaria rhynchophylla (Miq.) Jacks. that has been used in China for centuries as a "cognitive enhancer" as well as to treat strokes. We further investigated whether RIN and IRN effectively suppress release of proinflammatory cytokines in LPS-activated microglial cells and the underling molecular mechanism for the inhibition of microglial activation. RIN and IRN concentration-dependently attenuated LPS-induced production of proinflammatory cytokines such as TNF-alpha and IL-1beta as well as NO in mouse N9 microglial cells, with IRN showing more potent inhibition of microglial activation. The western blotting analysis indicated that the potential molecular mechanism for RIN or IRN-mediated attenuation was implicated in suppressions of iNOS protein level, phosphorylation of ERK and p38 MAPKs, and degradation of IkappaBalpha. In addition, the differential regulation of the three signaling pathways by two isomers was shown. Our results suggest that RIN and IRN may be effective therapeutic candidates for use in the treatment of neurodegenerative diseases accompanied by microglial activation.

After facial nerve damage, regenerating axons become aberrant throughout the length of the nerve and not only at the site of the lesion: an experimental study.

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Choi, D; Raisman, G

2004-02-01

After facial nerve trauma, aberrant regeneration is associated with synkinesis. Animal models of mechanical nerve guides or reparative cell transplants at the site of a lesion have not been shown to improve disorganized regeneration. We examined whether this is because regenerating axons become disorganized throughout the length of the nerve and not only at the site of the lesion. In rats (n = 12), retrograde fluorescent tracer techniques were used to establish that most of the temporal branch fibres were carried in the superior half of the facial nerve trunk. In two further groups of rats (n = 24) a complete proximal facial nerve lesion was made, and the nerve immediately repaired by suture. After 4 weeks, at a second operation, the superior half of the facial nerve trunk was cut, either proximal or distal to the original lesion, and retrograde tracers were applied to distal branches of the nerve. It was possible to localize the points at which regenerating fibres became aberrant in their course by studying the number of labelled motoneurons in the facial nucleus after application of the tracer to the temporal branch of the nerve: this was similar in the distal and proximal hemisection groups, suggesting that aberrant axonal development occurred throughout the length of the nerve. Future strategies aimed at improving the organization of regeneration need to provide guidance cues not only at the site of the lesion as previously thought, but also throughout the length of the nerve.

Regeneration of descending spinal axons after transection of the thoracic spinal cord during early development in the North American opossum, Didelphis virginiana.

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Martin, G F; Terman, J R; Wang, X M

2000-11-15

Opossums are born in an immature, fetal-like state, making it possible to lesion their spinal cord early in development without intrauterine surgery. When the thoracic spinal cord of the North American opossum, Didelphis virginiana, is transected on postnatal day 5, and injections of Fast Blue (FB) are made caudal to the lesion site 30-40 days or 6 months later, neurons are labeled in all of the spinal and supraspinal areas that are labeled after comparable injections in age-matched, unlesioned controls. Double-labeling studies document that regeneration of cut axons contributes to growth of axons through the lesion site and behavioral studies show that animals lesioned on postnatal day 5 use their hindlimbs in normal appearing locomotion as adults. The critical period for developmental plasticity of descending spinal axons extends to postnatal day 26, although axons which grow through the lesion site become fewer in number and more restricted as to origin with increasing age. Animals lesioned between postnatal day 12 and 26 use the hindlimbs better than animals lesioned as adults, but hindlimb function is markedly abnormal and uncoordinated with that of the forelimbs. We conclude that restoration of anatomical continuity occurs after transection of the spinal cord in developing opossums, that descending axons grow through the lesion site, that regeneration of cut axons contributes to such growth, and that animals lesioned early enough in development have relatively normal motor function as adults.

Regeneration of supraspinal axons after transection of the thoracic spinal cord in the developing opossum, Didelphis virginiana.

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Wang, X M; Terman, J R; Martin, G F

1998-08-17

When the thoracic spinal cord of the North American opossum is transected early in development, supraspinal axons grow through the lesion. In the experiments reported here, we asked whether regeneration of cut axons contributes to such growth. Fast Blue (FB) was injected into the lumbar cord on postnatal day (PD)5, 8, 15, or 20. Five days later, FB was removed by gentle suction, and the spinal cord was transected at thoracic levels. Fourteen days later, rhodamine B dextran was injected between the site of the FB injection and the lesion. The pups were maintained for an additional 7-10 days before killing and perfusion. We assumed that supraspinal neurons that contained FB survived axotomy and those that contained both FB and rhodamine B dextran supported regenerating axons. In the PD5 group (lesioned at PD10), regenerative growth was documented for axons originating in all of the supraspinal nuclei that innervate the lumbar cord by PD10. When the injections were made at the later ages, however, neurons that supported regenerative growth were fewer in number and regionally restricted. In some cases, they were limited primarily to the red nucleus, the medullary raphe, and the adjacent reticular formation. Our results show that regeneration of cut axons contributes to growth of supraspinal axons through the lesion after transection of the thoracic cord in developing opossums and that the critical period for regenerative growth is not the same for all axons.

A growing field: The regulation of axonal regeneration by Wnt signaling.

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Garcia, Armando L; Udeh, Adanna; Kalahasty, Karthik; Hackam, Abigail S

2018-01-01

The canonical Wnt/β-catenin pathway is a highly conserved signaling cascade that plays critical roles during embryogenesis. Wnt ligands regulate axonal extension, growth cone guidance and synaptogenesis throughout the developing central nervous system (CNS). Recently, studies in mammalian and fish model systems have demonstrated that Wnt/β-catenin signaling also promotes axonal regeneration in the adult optic nerve and spinal cord after injury, raising the possibility that Wnt could be developed as a therapeutic strategy. In this review, we summarize experimental evidence that reveals novel roles for Wnt signaling in the injured CNS, and discuss possible mechanisms by which Wnt ligands could overcome molecular barriers inhibiting axonal growth to promote regeneration. A central challenge in the neuroscience field is developing therapeutic strategies that induce robust axonal regeneration. Although adult axons have the capacity to respond to axonal guidance molecules after injury, there are several major obstacles for axonal growth, including extensive neuronal death, glial scars at the injury site, and lack of axonal guidance signals. Research in rodents demonstrated that activation of Wnt/β-catenin signaling in retinal neurons and radial glia induced neuronal survival and axonal growth, but that activation within reactive glia at the injury site promoted proliferation and glial scar formation. Studies in zebrafish spinal cord injury models confirm an axonal regenerative role for Wnt/β-catenin signaling and identified the cell types responsible. Additionally, in vitro and in vivo studies demonstrated that Wnt induces axonal and neurite growth through transcription-dependent effects of its central mediator β-catenin, potentially by inducing regeneration-promoting genes. Canonical Wnt signaling may also function through transcription-independent interactions of β-catenin with cytoskeletal elements, which could stabilize growing axons and control growth cone

Delta-opioid receptor analgesia is independent of microglial activation in a rat model of neuropathic pain.

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Joanna Mika

Full Text Available The analgesic effect of delta-opioid receptor (DOR ligands in neuropathic pain is not diminished in contrast to other opioid receptor ligands, which lose their effectiveness as analgesics. In this study, we examine whether this effect is related to nerve injury-induced microglial activation. We therefore investigated the influence of minocycline-induced inhibition of microglial activation on the analgesic effects of opioid receptor agonists: morphine, DAMGO, U50,488H, DPDPE, Deltorphin II and SNC80 after chronic constriction injury (CCI to the sciatic nerve in rats. Pre-emptive and repeated administration of minocycline (30 mg/kg, i.p. over 7 days significantly reduced allodynia and hyperalgesia as measured on day 7 after CCI. The antiallodynic and antihyperalgesic effects of intrathecally (i.t. administered morphine (10-20 µg, DAMGO (1-2 µg and U50,488H (25-50 µg were significantly potentiated in rats after minocycline, but no such changes were observed after DPDPE (10-20 µg, deltorphin II (1.5-15 µg and SNC80 (10-20 µg administration. Additionally, nerve injury-induced down-regulation of all types of opioid receptors in the spinal cord and dorsal root ganglia was not influenced by minocycline, which indicates that the effects of opioid ligands are dependent on other changes, presumably neuroimmune interactions. Our study of rat primary microglial cell culture using qRT-PCR, Western blotting and immunocytochemistry confirmed the presence of mu-opioid receptors (MOR and kappa-opioid receptors (KOR, further we provide the first evidence for the lack of DOR on microglial cells. In summary, DOR analgesia is different from analgesia induced by MOR and KOR receptors because it does not dependent on injury-induced microglial activation. DOR agonists appear to be the best candidates for new drugs to treat neuropathic pain.

Thymoquinone ameliorates lead-induced brain damage in Sprague Dawley rats.

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Radad, Khaled; Hassanein, Khaled; Al-Shraim, Mubarak; Moldzio, Rudolf; Rausch, Wolf-Dieter

2014-01-01

The present study aims to investigate the protective effects of thymoquinone, the major active ingredient of Nigella sativa seeds, against lead-induced brain damage in Sprague-Dawley rats. In which, 40 rats were divided into four groups (10 rats each). The first group served as control. The second, third and fourth groups received lead acetate, lead acetate and thymoquinone, and thymoquinone only, respectively, for one month. Lead acetate was given in drinking water at a concentration of 0.5 g/l (500 ppm). Thymoquinone was given daily at a dose of 20mg/kg b.w. in corn oil by gastric tube. Control and thymoquinone-treated rats showed normal brain histology. Treatment of rats with lead acetate was shown to produce degeneration of endothelial lining of brain blood vessels with peri-vascular cuffing of mononuclear cells consistent to lymphocytes, congestion of choroid plexus blood vessels, ischemic brain infarction, chromatolysis and neuronal degeneration, microglial reaction and neuronophagia, degeneration of hippocampal and cerebellar neurons, and axonal demyelination. On the other hand, co-administration of thymoquinone with lead acetate markedly decreased the incidence of lead acetate-induced pathological lesions. Thus the current study shed some light on the beneficial effects of thymoquinone against neurotoxic effects of lead in rats. Copyright © 2013 Elsevier GmbH. All rights reserved.

Polysaccharides from Ganoderma lucidum attenuate microglia-mediated neuroinflammation and modulate microglial phagocytosis and behavioural response.

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Cai, Qing; Li, Yuanyuan; Pei, Gang

2017-03-24

Ganoderma lucidum (GL) has been widely used in Asian countries for hundreds of years to promote health and longevity. The pharmacological functions of which had been classified, including the activation of innate immune responses, suppression of tumour and modulation of cell proliferations. Effective fractions of Ganoderma lucidum polysaccharides (GLP) had already been reported to regulate the immune system. Nevertheless, the role of GLP in the microglia-mediated neuroinflammation has not been sufficiently elucidated. Further, GLP effect on microglial behavioural modulations in correlation with the inflammatory responses remains to be unravelled. The aim of this work was to quantitatively analyse the contributions of GLP on microglia. The BV2 microglia and primary mouse microglia were stimulated by lipopolysaccharides (LPS) and amyloid beta 42 (Aβ 42 ) oligomer, respectively. Investigation on the effect of GLP was carried by quantitative determination of the microglial pro- and anti-inflammatory cytokine expressions and behavioural modulations including migration, morphology and phagocytosis. Analysis of microglial morphology and phagocytosis modulations was confirmed in the zebrafish brain. Quantitative results revealed that GLP down-regulates LPS- or Aβ-induced pro-inflammatory cytokines and promotes anti-inflammatory cytokine expressions in BV-2 and primary microglia. In addition, GLP attenuates inflammation-related microglial migration, morphological alterations and phagocytosis probabilities. We also showed that modulations of microglial behavioural responses were associated with MCP-1 and C1q expressions. Overall, our study provides an insight into the GLP regulation of LPS- and Aβ-induced neuroinflammation and serves an implication that the neuroprotective function of GLP might be achieved through modulation of microglial inflammatory and behavioural responses.

Levo-Tetrahydropalmatine Attenuates Bone Cancer Pain by Inhibiting Microglial Cells Activation

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Mao-yin Zhang

2015-01-01

Full Text Available Objective. The present study is to investigate the analgesic roles of L-THP in rats with bone cancer pain caused by tumor cell implantation (TCI. Methods. Thermal hyperalgesia and mechanical allodynia were measured at different time points before and after operation. L-THP (20, 40, and 60 mg/kg were administrated intragastrically at early phase of postoperation (before pain appearance and later phase of postoperation (after pain appearance, respectively. The concentrations of TNF-α, IL-1β, and IL-18 in spinal cord were measured by enzyme-linked immunosorbent assay. Western blot was used to test the activation of astrocytes and microglial cells in spinal cord after TCI treatment. Results. TCI treatment induced significant thermal hyperalgesia and mechanical allodynia. Administration of L-THP at high doses significantly prevented and/or reversed bone cancer-related pain behaviors. Besides, TCI-induced activation of microglial cells and the increased levels of TNF-α and IL-18 were inhibited by L-THP administration. However, L-THP failed to affect TCI-induced astrocytes activation and IL-1β increase. Conclusion. This study suggests the possible clinical utility of L-THP in the treatment of bone cancer pain. The analgesic effects of L-THP on bone cancer pain maybe underlying the inhibition of microglial cells activation and proinflammatory cytokines increase.

Retention of retinal axon collateral is responsible for induced ipsilateral retinotectal projections in adult goldfish.

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Sharma, S C; Tsai, C

1991-01-01

In normal goldfish, optic axons innervate only the contralateral optic tectum. When one eye was enucleated and the optic nerve of the other eye crushed, the regenerating optic axons innervated both optic tecta. We studied the presence of bilaterally projecting retinal ganglion cells by double retrograde cell labeling methods using Nuclear Yellow and True Blue dyes. About 10% of the retinal ganglion cells were double labeled and these cells were found throughout the retina. In addition, HRP application to the ipsilateral tectum revealed retrogradely-labeled retinal ganglion cells of all morphological types. These results suggest that induced ipsilateral projections are formed by regenerating axon collaterals and that all cell types are involved in the generation of normal mirror image typography.

Inhibitors of Microglial Neurotoxicity: Focus on Natural Products

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Kyoungho Suk

2011-01-01

Full Text Available Microglial cells play a dual role in the central nervous system as they have both neurotoxic and neuroprotective effects. Uncontrolled and excessive activation of microglia often contributes to inflammation-mediated neurodegeneration. Recently, much attention has been paid to therapeutic strategies aimed at inhibiting neurotoxic microglial activation. Pharmacological inhibitors of microglial activation are emerging as a result of such endeavors. In this review, natural products-based inhibitors of microglial activation will be reviewed. Potential neuroprotective activity of these compounds will also be discussed. Future works should focus on the discovery of novel drug targets that specifically mediate microglial neurotoxicity rather than neuroprotection. Development of new drugs based on these targets may require a better understanding of microglial biology and neuroinflammation at the molecular, cellular, and systems levels.

Lesion of the locus coeruleus aggravates dopaminergic neuron degeneration by modulating microglial function in mouse models of Parkinson׳s disease.

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Yao, Ning; Wu, Yanhong; Zhou, Yan; Ju, Lili; Liu, Yujun; Ju, Rongkai; Duan, Deyi; Xu, Qunyuan

2015-11-02

The degeneration of noradrenergic neurons in the locus coeruleus (LC) commonly occurs in patients with Parkinson's disease (PD), which is characterized by a selective injury of dopaminergic neurons in the substantia nigra (SN). The pathological impact of the LC on the SN in the disease is unknown. In the present study, we used a noradrenergic toxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4), to deplete noradrenaline (NA) derived from the LC to explore its influence on degeneration or injury of dopaminergic neurons in the SN in mouse model produced by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or lipopolysaccharide (LPS). Our results demonstrated that lesion of the LC could change microglial function in the brain, which led to enhanced or prolonged expression of pro-inflammatory cytokines, diminished neurotrophic factors, and weakened ability of anti-oxidation in the SN. The in vitro experiments further confirmed that NA could reduce the inflammatory reaction of microglia. The selective injury of dopaminergic neurons by inflammation, however, was due to the inflammation in different brain regions rather than the depletion of NA. Our results indicate that the lesion in the LC is an important factor in promoting dopaminergic neuron degeneration by impacting the function of microglia in the midbrain. Copyright © 2015 Elsevier B.V. All rights reserved.

SnoN facilitates axonal regeneration after spinal cord injury.

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Jiun L Do

Full Text Available Adult CNS neurons exhibit a reduced capacity for growth compared to developing neurons, due in part to downregulation of growth-associated genes as development is completed. We tested the hypothesis that SnoN, an embryonically regulated transcription factor that specifies growth of the axonal compartment, can enhance growth in injured adult neurons. In vitro, SnoN overexpression in dissociated adult DRG neuronal cultures significantly enhanced neurite outgrowth. Moreover, TGF-β1, a negative regulator of SnoN, inhibited neurite outgrowth, and SnoN over-expression overcame this inhibition. We then examined whether SnoN influenced axonal regeneration in vivo: indeed, expression of a mutant form of SnoN resistant to degradation significantly enhanced axonal regeneration following cervical spinal cord injury, despite peri-lesional upregulation of TGF-β1. Thus, a developmental mechanism that specifies extension of the axonal compartment also promotes axonal regeneration after adult CNS injury.

Peripheral formalin injection induces unique spinal cord microglial phenotypic changes

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Fu, Kai-Yuan; Tan, Yong-Hui; Sung, Backil; Mao, Jianren

2014-01-01

Microglia are resident immune cells of brain and activated by peripheral tissue injury. In the present study, we investigated the possible induction of several microglial surface immunomolecules in the spinal cord, including leukocyte common antigen (LCA/CD45), MHC class I antigen, MHC class II antigen, Fc receptor, and CD11c following formalin injection into the rat’s hind paw. CD45 and MHC class I were upregulated in the activated microglia, which was evident on day 3 with the peak expression on day 7 following peripheral formalin injection. There was a very low basal expression of MHC class II, CD11c, and the Fc receptor, which did not change after the formalin injection. These results, for the first time, indicate that peripheral formalin injection can induce phenotypic changes of microglia with distinct upregulation of CD45 and MHC class I antigen. The data suggest that phenotypic changes of the activated microglia may be a unique pattern of central changes following peripheral tissue injury. PMID:19015000

Neuroprotection of Scutellarin is mediated by inhibition of microglial inflammatory activation.

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Wang, S; Wang, H; Guo, H; Kang, L; Gao, X; Hu, L

2011-06-30

Inhibition of microglial over-reaction and the inflammatory processes may represent a therapeutic target to alleviate the progression of neurological diseases, such as neurodegenerative diseases and stroke. Scutellarin is the major active component of Erigeron breviscapus (Vant.) Hand-Mazz, a herbal medicine in treatment of cerebrovascular diseases for a long time in the Orient. In this study, we explored the mechanisms of neuroprotection by Scutellarin, particularly its anti-inflammatory effects in microglia. We observed that Scutellarin inhibited lipopolysaccharide (LPS)-induced production of proinflammatory mediators such as nitric oxide (NO), tumor necrosis factor α (TNFα), interleukin-1β (IL-1β) and reactive oxygen species (ROS), suppressed LPS-stimulated inducible nitric oxide synthase (iNOS), TNFα, and IL-1β mRNA expression in rat primary microglia or BV-2 mouse microglial cell line. Scutellarin inhibited LPS-induced nuclear translocation and DNA binding activity of nuclear factor κB (NF-κB). It repressed the LPS-induced c-Jun N-terminal kinase (JNK) and p38 phosphorylation without affecting the activity of extracellular signal regulated kinase (ERK) mitogen-activated protein kinase. Moreover, Scutellarin also inhibited interferon-γ (IFN-γ)-induced NO production, iNOS mRNA expression and transcription factor signal transducer and activator of transcription 1α (STAT1α) activation. Concomitantly, conditioned media from Scutellarin pretreated BV-2 cells significantly reduced neurotoxicity compared with conditioned media from LPS treated alone. Together, the present study reported the anti-inflammatory activity of Scutellarin in microglial cells along with their underlying molecular mechanisms, and suggested Scutellarin might have therapeutic potential for various microglia mediated neuroinflammation. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Induction of Microglial Activation by Mediators Released from Mast Cells

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Xiang Zhang

2016-04-01

Full Text Available Background/Aims: Microglia are the resident immune cells in the brain and play a pivotal role in immune surveillance in the central nervous system (CNS. Brain mast cells are activated in CNS disorders and induce the release of several mediators. Thus, brain mast cells, rather than microglia, are the “first responders” due to injury. However, the functional aspects of mast cell-microglia interactions remain uninvestigated. Methods: Conditioned medium from activated HMC-1 cells induces microglial activation similar to co-culture of microglia with HMC-1 cells. Primary cultured microglia were examined by flow cytometry analysis and confocal microscopy. TNF- alpha and IL-6 were measured with commercial ELISA kits. Cell signalling was analysed by Western blotting. Results: In the present study, we found that the conditioned medium from activated HMC-1 cells stimulated microglial activation and the subsequent production of the pro-inflammatory factors TNF-α and IL-6. Co-culture of microglia and HMC-1 cells with corticotropin-releasing hormone (CRH for 24, 48 and 72 hours increased TNF-α and IL-6 production. Antagonists of histamine receptor 1 (H1R, H4R, proteinase-activated receptor 2 (PAR2 or Toll-like receptor 4 (TLR4 reduced HMC-1-induced pro-inflammatory factor production and MAPK and PI3K/AKT pathway activation. Conclusions: These results imply that activated mast cells trigger microglial activation. Interactions between mast cells and microglia could constitute a new and unique therapeutic target for CNS inflammation-related diseases.

Rod-like microglia are restricted to eyes with laser-induced ocular hypertension but absent from the microglial changes in the contralateral untreated eye.

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Rosa de Hoz

Full Text Available In the mouse model of unilateral laser-induced ocular hypertension (OHT the microglia in both the treated and the normotensive untreated contralateral eye have morphological signs of activation and up-regulation of MHC-II expression in comparison with naïve. In the brain, rod-like microglia align to less-injured neurons in an effort to limit damage. We investigate whether: i microglial activation is secondary to laser injury or to a higher IOP and; ii the presence of rod-like microglia is related to OHT. Three groups of mice were used: age-matched control (naïve, n=15; and two lasered: limbal (OHT, n=15; and non-draining portion of the sclera (scleral, n=3. In the lasered animals, treated eyes as well as contralateral eyes were analysed. Retinal whole-mounts were immunostained with antibodies against, Iba-1, NF-200, MHC-II, CD86, CD68 and Ym1. In the scleral group (normal ocular pressure no microglial signs of activation were found. Similarly to naïve eyes, OHT-eyes and their contralateral eyes had ramified microglia in the nerve-fibre layer related to the blood vessel. However, only eyes with OHT had rod-like microglia that aligned end-to-end, coupling to form trains of multiple cells running parallel to axons in the retinal surface. Rod-like microglia were CD68+ and were related to retinal ganglion cells (RGCs showing signs of degeneration (NF-200+RGCs. Although MHC-II expression was up-regulated in the microglia of the NFL both in OHT-eyes and their contralateral eyes, no expression of CD86 and Ym1 was detected in ramified or in rod-like microglia. After 15 days of unilateral lasering of the limbal and the non-draining portion of the sclera, activated microglia was restricted to OHT-eyes and their contralateral eyes. However, rod-like microglia were restricted to eyes with OHT and degenerated NF-200+RGCs and were absent from their contralateral eyes. Thus, rod-like microglia seem be related to the neurodegeneration associated with HTO.

TAM receptors regulate multiple features of microglial physiology.

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Fourgeaud, Lawrence; Través, Paqui G; Tufail, Yusuf; Leal-Bailey, Humberto; Lew, Erin D; Burrola, Patrick G; Callaway, Perri; Zagórska, Anna; Rothlin, Carla V; Nimmerjahn, Axel; Lemke, Greg

2016-04-14

Microglia are damage sensors for the central nervous system (CNS), and the phagocytes responsible for routine non-inflammatory clearance of dead brain cells. Here we show that the TAM receptor tyrosine kinases Mer and Axl regulate these microglial functions. We find that adult mice deficient in microglial Mer and Axl exhibit a marked accumulation of apoptotic cells specifically in neurogenic regions of the CNS, and that microglial phagocytosis of the apoptotic cells generated during adult neurogenesis is normally driven by both TAM receptor ligands Gas6 and protein S. Using live two-photon imaging, we demonstrate that the microglial response to brain damage is also TAM-regulated, as TAM-deficient microglia display reduced process motility and delayed convergence to sites of injury. Finally, we show that microglial expression of Axl is prominently upregulated in the inflammatory environment that develops in a mouse model of Parkinson's disease. Together, these results establish TAM receptors as both controllers of microglial physiology and potential targets for therapeutic intervention in CNS disease.

Riluzole protects against glutamate-induced slowing of neurofilament axonal transport.

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Stevenson, Alison

2009-04-24

Riluzole is the only drug approved for the treatment of amyotrophic lateral sclerosis (ALS) but its precise mode of action is not properly understood. Damage to axonal transport of neurofilaments is believed to be part of the pathogenic mechanism in ALS and this has been linked to defective glutamate handling and increased phosphorylation of neurofilament side-arm domains. Here, we show that riluzole protects against glutamate-induced slowing of neurofilament transport. Protection is associated with decreased neurofilament side-arm phosphorylation and inhibition of the activities of two neurofilament kinases, ERK and p38 that are activated in ALS. Thus, the anti-glutamatergic properties of riluzole include protection against glutamate-induced changes to neurofilament phosphorylation and transport.

Microglial response to Alzheimer's disease is differentially modulated by voluntary wheel running and enriched environments.

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Rodríguez, J J; Noristani, H N; Verkhratsky, A

2015-03-01

Alzheimer's disease (AD) is an untreatable neurodegenerative disease that deteriorates memory. Increased physical/cognitive activity reduces dementia risk by promoting neuronal and glial response. Although few studies have investigated microglial response in wild-type rodents following exposure to physical/cognitive stimulation, environmental-induced changes of microglia response to AD have been neglected. We investigated effects of running (RUN) and enriched (ENR) environments on numerical density (N v, #/mm(3)) and morphology of microglia in a triple transgenic (3×Tg-AD) mouse model of AD that closely mimics AD pathology in humans. We used immunohistochemical approach to characterise microglial domain by measuring their overall cell surface, volume and somata volume. 3×Tg-AD mice housed in standard control (STD) environment showed significant increase in microglial N v (11.7 %) in CA1 stratum lacunosum moleculare (S.Mol) of the hippocampus at 12 months compared to non-transgenic (non-Tg) animals. Exposure to combined RUN and ENR environments prevented an increase in microglial N v in 3×Tg-AD and reduced microglial numbers to non-Tg control levels. Interestingly, 3×Tg-AD mice housed solely in ENR environment displayed significant decrease in microglial N v in CA1 subfield (9.3 % decrease), stratum oriens (11.5 % decrease) and S.Mol (7.6 % decrease) of the hippocampus compared to 3×Tg-AD mice housed in STD environment. Morphological analysis revealed microglial hypertrophy due to pronounced increase in microglia surface, volume and somata volume (61, 78 and 41 %) in 3×Tg-AD mice housed in RUN (but not in ENR) compared to STD environment. These results indicate that exposure to RUN and ENR environments have differential effects on microglial density and activation-associated changes in microglial morphology.

T-cell- and macrophage-mediated axon damage in the absence of a CNS-specific immune response: involvement of metalloproteinases.

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Newman, T A; Woolley, S T; Hughes, P M; Sibson, N R; Anthony, D C; Perry, V H

2001-11-01

Recent evidence has highlighted the fact that axon injury is an important component of multiple sclerosis pathology. The issue of whether a CNS antigen-specific immune response is required to produce axon injury remains unresolved. We investigated the extent and time course of axon injury in a rodent model of a delayed-type hypersensitivity (DTH) reaction directed against the mycobacterium bacille Calmette-Guérin (BCG). Using MRI, we determined whether the ongoing axon injury is restricted to the period during which the blood-brain barrier is compromised. DTH lesions were initiated in adult rats by intracerebral injection of heat-killed BCG followed by a peripheral challenge with BCG. Our findings demonstrate that a DTH reaction to a non-CNS antigen within a CNS white matter tract leads to axon injury. Ongoing axon injury persisted throughout the 3-month period studied and was not restricted to the period of blood-brain barrier breakdown, as detected by MRI enhancing lesions. We have previously demonstrated that matrix metalloproteinases (MMPs) are upregulated in multiple sclerosis plaques and DTH lesions. In this study we demonstrated that microinjection of activated MMPs into the cortical white matter results in axon injury. Our results show that axon injury, possibly mediated by MMPs, is immunologically non-specific and may continue behind an intact blood-brain barrier.

Microglial migration and interactions with dendrimer nanoparticles are altered in the presence of neuroinflammation.

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Zhang, Fan; Nance, Elizabeth; Alnasser, Yossef; Kannan, Rangaramanujam; Kannan, Sujatha

2016-03-22

Microglial cells have been implicated in neuroinflammation-mediated injury in the brain, including neurodevelopmental disorders such as cerebral palsy (CP) and autism. Pro-inflammatory activation of microglial cells results in the impairment of their neuroprotective functions, leading to an exaggerated, ongoing immune dysregulation that can persist long after the initial insult. We have previously shown that dendrimer-mediated delivery of an anti-inflammatory agent can attenuate inflammation in a rabbit model of maternal inflammation-induced CP and significantly improve the motor phenotype, due to the ability of the dendrimer to selectively localize in activated microglia. To elucidate the interactions between dendrimers and microglia, we created an organotypic whole-hemisphere brain slice culture model from newborn rabbits with and without exposure to inflammation in utero. We then used this model to analyze the dynamics of microglial migration and their interactions with dendrimers in the presence of neuroinflammation. Microglial cells in animals with CP had an amoeboid morphology and impaired cell migration, demonstrated by decreased migration distance and velocity when compared to cells in healthy, age-matched controls. However, this decreased migration was associated with a greater, more rapid dendrimer uptake compared to microglial cells from healthy controls. This study demonstrates that maternal intrauterine inflammation is associated with impaired microglial function and movement in the newborn brain. This microglial impairment may play a role in the development of ongoing brain injury and CP in the offspring. Increased uptake of dendrimers by the "impaired" microglia can be exploited to deliver drugs specifically to these cells and modulate their functions. Host tissue and target cell characteristics are important aspects to be considered in the design and evaluation of targeted dendrimer-based nanotherapeutics for improved and sustained efficacy. This ex

Computed tomography in diagnosis of diffuse axonal injury

International Nuclear Information System (INIS)

Iwadate, Yasuo; Ono, Juniti; Okimura, Yoshitaka; Suda, Sumio; Isobe, Katsumi; Yamaura, Akira.

1990-01-01

Diffuse axonal injury (DAI) has been described in instances of prolonged traumatic coma on the basis of the neuropathological findings, but the same findings are also found in patients with cerebral concussion. Experimental studies confirm that the quality of survivors following trauma is directly proportional to the amount of primarily injured-axon. When the injured axon lies in a widespread area of the brain, outcome for the patient is always poor. In a series of 260 severely head-injured patients, based on their poor outcome, 69 (27%) were diagnosed as DAI. Because of their relatively good outcome, eighty-two patients (32%) were classified into non-DAI group. The predominant CT finding of DAI patients was intraparenchymal deep-seated hemorrhagic lesion. This was observed in 28 patients (41%). Normal CT was also observed in 11 patients (16%). On the other hand, 8 of the non-DAI group (10%) manifested deep-seated lesions. Diffuse cerebral swelling (DCS) appeared in both groups in the same incidence. Subarachnoid hematoma in the perimesencephalic cistern (SAH (PMC)) and intraventricular hematoma (IVH) were observed in 64% of the DAI group, and in 23% of the non-DAI group. The available evidence indicates that various types of hematoma seen in the deep-seated structures of the brain do not have an absolute diagnostic value, but the frequency of hematoma is thought to increase in proportion to the amount of injured-axon. (author)

PI3K-GSK3 signalling regulates mammalian axon regeneration by inducing the expression of Smad1

Science.gov (United States)

Saijilafu; Hur, Eun-Mi; Liu, Chang-Mei; Jiao, Zhongxian; Xu, Wen-Lin; Zhou, Feng-Quan

2013-10-01

In contrast to neurons in the central nervous system, mature neurons in the mammalian peripheral nervous system (PNS) can regenerate axons after injury, in part, by enhancing intrinsic growth competence. However, the signalling pathways that enhance the growth potential and induce spontaneous axon regeneration remain poorly understood. Here we reveal that phosphatidylinositol 3-kinase (PI3K) signalling is activated in response to peripheral axotomy and that PI3K pathway is required for sensory axon regeneration. Moreover, we show that glycogen synthase kinase 3 (GSK3), rather than mammalian target of rapamycin, mediates PI3K-dependent augmentation of the growth potential in the PNS. Furthermore, we show that PI3K-GSK3 signal is conveyed by the induction of a transcription factor Smad1 and that acute depletion of Smad1 in adult mice prevents axon regeneration in vivo. Together, these results suggest PI3K-GSK3-Smad1 signalling as a central module for promoting sensory axon regeneration in the mammalian nervous system.

Increased mitochondrial content in remyelinated axons: implications for multiple sclerosis

Science.gov (United States)

Zambonin, Jessica L.; Zhao, Chao; Ohno, Nobuhiko; Campbell, Graham R.; Engeham, Sarah; Ziabreva, Iryna; Schwarz, Nadine; Lee, Sok Ee; Frischer, Josa M.; Turnbull, Doug M.; Trapp, Bruce D.; Lassmann, Hans; Franklin, Robin J. M.

2011-01-01

Mitochondrial content within axons increases following demyelination in the central nervous system, presumably as a response to the changes in energy needs of axons imposed by redistribution of sodium channels. Myelin sheaths can be restored in demyelinated axons and remyelination in some multiple sclerosis lesions is extensive, while in others it is incomplete or absent. The effects of remyelination on axonal mitochondrial content in multiple sclerosis, particularly whether remyelination completely reverses the mitochondrial changes that follow demyelination, are currently unknown. In this study, we analysed axonal mitochondria within demyelinated, remyelinated and myelinated axons in post-mortem tissue from patients with multiple sclerosis and controls, as well as in experimental models of demyelination and remyelination, in vivo and in vitro. Immunofluorescent labelling of mitochondria (porin, a voltage-dependent anion channel expressed on all mitochondria) and axons (neurofilament), and ultrastructural imaging showed that in both multiple sclerosis and experimental demyelination, mitochondrial content within remyelinated axons was significantly less than in acutely and chronically demyelinated axons but more numerous than in myelinated axons. The greater mitochondrial content within remyelinated, compared with myelinated, axons was due to an increase in density of porin elements whereas increase in size accounted for the change observed in demyelinated axons. The increase in mitochondrial content in remyelinated axons was associated with an increase in mitochondrial respiratory chain complex IV activity. In vitro studies showed a significant increase in the number of stationary mitochondria in remyelinated compared with myelinated and demyelinated axons. The number of mobile mitochondria in remyelinated axons did not significantly differ from myelinated axons, although significantly greater than in demyelinated axons. Our neuropathological data and findings in

Analysis of axonal regeneration in the central and peripheral nervous systems of the NG2-deficient mouse

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Lieberman Alexander R

2007-09-01

Full Text Available Abstract Background The chondroitin sulphate proteoglycan NG2 blocks neurite outgrowth in vitro and has been proposed as a major inhibitor of axonal regeneration in the CNS. Although a substantial body of evidence underpins this hypothesis, it is challenged by recent findings including strong expression of NG2 in regenerating peripheral nerve. Results We studied axonal regeneration in the PNS and CNS of genetically engineered mice that do not express NG2, and in sex and age matched wild-type controls. In the CNS, we used anterograde tracing with BDA to study corticospinal tract (CST axons after spinal cord injury and transganglionic labelling with CT-HRP to trace ascending sensory dorsal column (DC axons after DC lesions and a conditioning lesion of the sciatic nerve. Injury to these fibre tracts resulted in no difference between knockout and wild-type mice in the ability of CST axons or DC axons to enter or cross the lesion site. Similarly, after dorsal root injury (with conditioning lesion, most regenerating dorsal root axons failed to grow across the dorsal root entry zone in both transgenic and wild-type mice. Following sciatic nerve injuries, functional recovery was assessed by analysis of the toe-spreading reflex and cutaneous sensitivity to Von Frey hairs. Anatomical correlates of regeneration were assessed by: retrograde labelling of regenerating dorsal root ganglion (DRG cells with DiAsp; immunostaining with PGP 9.5 to visualise sensory reinnervation of plantar hindpaws; electron microscopic analysis of regenerating axons in tibial and digital nerves; and by silver-cholinesterase histochemical study of motor end plate reinnervation. We also examined functional and anatomical correlates of regeneration after injury of the facial nerve by assessing the time taken for whisker movements and corneal reflexes to recover and by retrograde labelling of regenerated axons with Fluorogold and DiAsp. None of the anatomical or functional analyses

Time course of ongoing activity during neuritis and following axonal transport disruption.

Science.gov (United States)

Satkeviciute, Ieva; Goodwin, George; Bove, Geoffrey M; Dilley, Andrew

2018-05-01

Local nerve inflammation (neuritis) leads to ongoing activity and axonal mechanical sensitivity (AMS) along intact nociceptor axons and disrupts axonal transport. This phenomenon forms the most feasible cause of radiating pain, such as sciatica. We have previously shown that axonal transport disruption without inflammation or degeneration also leads to AMS but does not cause ongoing activity at the time point when AMS occurs, despite causing cutaneous hypersensitivity. However, there have been no systematic studies of ongoing activity during neuritis or noninflammatory axonal transport disruption. In this study, we present the time course of ongoing activity from primary sensory neurons following neuritis and vinblastine-induced axonal transport disruption. Whereas 24% of C/slow Aδ-fiber neurons had ongoing activity during neuritis, few (disruption of axonal transport without inflammation does not lead to ongoing activity in sensory neurons, including nociceptors, but does cause a rapid and transient development of AMS. Because it is proposed that AMS underlies mechanically induced radiating pain, and a transient disruption of axonal transport (as previously reported) leads to transient AMS, it follows that processes that disrupt axonal transport, such as neuritis, must persist to maintain AMS and the associated symptoms. NEW & NOTEWORTHY Many patients with radiating pain lack signs of nerve injury on clinical examination but may have neuritis, which disrupts axonal transport. We have shown that axonal transport disruption does not induce ongoing activity in primary sensory neurons but does cause transient axonal mechanical sensitivity. The present data complete a profile of key axonal sensitivities following axonal transport disruption. Collectively, this profile supports that an active peripheral process is necessary for maintained axonal sensitivities.

Astrocyte galectin-9 potentiates microglial TNF secretion.

Science.gov (United States)

Steelman, Andrew J; Li, Jianrong

2014-08-27

Aberrant neuroinflammation is suspected to contribute to the pathogenesis of myriad neurological diseases. As such, determining the pathways that promote or inhibit glial activation is of interest. Activation of the surface glycoprotein T-cell immunoglobulin and mucin-domain containing protein 3 (Tim-3) by the lectin galectin-9 has been implicated in promoting innate immune cell activation by potentiating or synergizing toll-like receptor (TLR) signaling. In the present study we examined the role of the Tim-3/galectin-9 pathway in glial activation in vitro. Primary monocultures of microglia or astrocytes, co-cultures containing microglia and astrocytes, and mixed glial cultures consisting of microglia, astrocytes and oligodendrocytes were stimulated with poly(I:C) or LPS, and galectin-9 up-regulation was determined. The effect of endogenous galectin-9 production on microglial activation was examined using cultures from wild-type and Lgals9 null mice. The ability for recombinant galectin-9 to promote microglia activation was also assessed. Tim-3 expression on microglia and BV2 cells was examined by qPCR and flow cytometry and its necessity in transducing the galectin-9 signal was determined using a Tim-3 specific neutralizing antibody or recombinant soluble Tim-3. Astrocytes potentiated TNF production from microglia following TLR stimulation. Poly(I:C) stimulation increased galectin-9 expression in microglia and microglial-derived factors promoted galectin-9 up-regulation in astrocytes. Astrocyte-derived galectin-9 in turn enhanced microglial TNF production. Similarly, recombinant galectin-9 enhanced poly(I:C)-induced microglial TNF and IL-6 production. Inhibition of Tim-3 did not alter TNF production in mixed glial cultures stimulated with poly(I:C). Galectin-9 functions as an astrocyte-microglia communication signal and promotes cytokine production from microglia in a Tim-3 independent manner. Activation of CNS galectin-9 likely modulates neuroinflammatory

Lentiviral-mediated expression of polysialic acid in spinal cord and conditioning lesion promote regeneration of sensory axons into spinal cord

NARCIS (Netherlands)

Zhang, Yi; Zhang, Xinyu; Wu, Dongsheng; Verhaagen, J.; Richardson, Peter M; Yeh, John; Bo, Xuenong

2007-01-01

In adult mammals, sensory axons that regenerate in the dorsal root are unable to grow across the dorsal root entry zone (DREZ) into the spinal cord. In this study we examined whether, by inducing expression of polysialic acid (PSA) (a large carbohydrate attached to molecules on the cell surface), in

Brain Renin-Angiotensin System and Microglial Polarization: Implications for Aging and Neurodegeneration

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Jose L. Labandeira-Garcia

2017-05-01

Full Text Available Microglia can transform into proinflammatory/classically activated (M1 or anti-inflammatory/alternatively activated (M2 phenotypes following environmental signals related to physiological conditions or brain lesions. An adequate transition from the M1 (proinflammatory to M2 (immunoregulatory phenotype is necessary to counteract brain damage. Several factors involved in microglial polarization have already been identified. However, the effects of the brain renin-angiotensin system (RAS on microglial polarization are less known. It is well known that there is a “classical” circulating RAS; however, a second RAS (local or tissue RAS has been observed in many tissues, including brain. The locally formed angiotensin is involved in local pathological changes of these tissues and modulates immune cells, which are equipped with all the components of the RAS. There are also recent data showing that brain RAS plays a major role in microglial polarization. Level of microglial NADPH-oxidase (Nox activation is a major regulator of the shift between M1/proinflammatory and M2/immunoregulatory microglial phenotypes so that Nox activation promotes the proinflammatory and inhibits the immunoregulatory phenotype. Angiotensin II (Ang II, via its type 1 receptor (AT1, is a major activator of the NADPH-oxidase complex, leading to pro-oxidative and pro-inflammatory effects. However, these effects are counteracted by a RAS opposite arm constituted by Angiotensin II/AT2 receptor signaling and Angiotensin 1–7/Mas receptor (MasR signaling. In addition, activation of prorenin-renin receptors may contribute to activation of the proinflammatory phenotype. Aged brains showed upregulation of AT1 and downregulation of AT2 receptor expression, which may contribute to a pro-oxidative pro-inflammatory state and the increase in neuron vulnerability. Several recent studies have shown interactions between the brain RAS and different factors involved in microglial polarization

Regeneración axonal posterior a lesiones traumáticas de médula espinal: Papel crítico de galectina-1

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Héctor R Quintá

2014-08-01

Full Text Available Al producirse una lesión de médula espinal (LME, un sinnúmero de proteínas inhibidoras de la regeneración axonal ocupan el sitio de lesión en forma secuencial. La primer proteína en llegar al mismo se conoce como semaforina 3A (Sema3A, siendo además una de las más potentes por su acción de inhibir la regeneración axonal. A nivel mecanístico la unión de esta proteína al complejo-receptor neuronal neuropilin-1 (NRP-1/PlexinA4 evita que se produzca regeneración axonal. En este trabajo de revisión se discutirá la acción de galectin-1 (Gal-1, una proteína endógena de unión a glicanos, que selectivamente se une al complejo-receptor NRP-1/PlexinA4 de las neuronas lesionadas a través de un mecanismo dependiente de interacciones lectina-glicano, interrumpiendo la señalización generada por Sema3A y permitiendo de esta manera la regeneración axonal y recuperación locomotora luego de producirse la LME. Mientras ambas formas de Gal-1 (monomérica y dimérica contribuyen a la inactivación de la microglia, solo la forma dimérica de Gal-1 es capaz de unirse al complejo-receptor NRP-1/PlexinA4 y promover regeneración axonal. Por lo tanto, Gal-1 dimérica produce recuperación de las lesiones espinales interfiriendo en la señalización de Sema3A a través de la unión al complejo-receptor NRP-1/PlexinA4, sugiriendo el uso de esta lectina en su forma dimérica para el tratamiento de pacientes con LME.

Microglial AGE-albumin is critical for neuronal death in Parkinson's disease: a possible implication for theranostics.

Science.gov (United States)

Bayarsaikhan, Enkhjargal; Bayarsaikhan, Delger; Lee, Jaesuk; Son, Myeongjoo; Oh, Seyeon; Moon, Jeongsik; Park, Hye-Jeong; Roshini, Arivazhagan; Kim, Seung U; Song, Byoung-Joon; Jo, Seung-Mook; Byun, Kyunghee; Lee, Bonghee

2015-01-01

Advanced glycation end products (AGEs) are known to play an important role in the pathogenesis of neurodegenerative diseases, including Parkinson's disease (PD), by inducing protein aggregation and cross-link, formation of Lewy body, and neuronal death. In this study, we observed that AGE-albumin, the most abundant AGE product in the human PD brain, is synthesized in activated microglial cells and accumulates in the extracellular space. AGE-albumin synthesis in human-activated microglial cells is distinctly inhibited by ascorbic acid and cytochalasin treatment. Accumulated AGE-albumin upregulates the receptor to AGE, leading to apoptosis of human primary dopamine (DA) neurons. In animal experiments, we observed reduced DA neuronal cell death by treatment with soluble receptor to AGE. Our study provides evidence that activated microglial cells are one of the main contributors in AGE-albumin accumulation, deleterious to DA neurons in human and animal PD brains. Finally, activated microglial AGE-albumin could be used as a diagnostic and therapeutic biomarker with high sensitivity for neurodegenerative disorders, including PD.

Synergistic Effects of Psychosocial Stress and Mild Peripheral Infection on Inducing Microglial Activation in the Hippocampal Dentate Gyrus and Long-Lasting Deficits in Hippocampus-Related Memory.

Science.gov (United States)

Tzeng, Wen-Yu; Su, Chien-Chou; Sun, Li-Han; Cherng, Chianfang G.; Yu, Lung

2018-04-30

Lipopolysaccharide (LPS) treatment and stress may cause immune activation in the brain, an event which has been thought to play a role in mediating stress-induced cognitive dysfunction. However, the enduring impact of psychosocial stress on brain immune activation or cognitive deficits has not been well investigated. Likewise, it remains unexplored whether there exist synergistic effects of psychosocial stress and a weak systemic LPS treatment on brain immune activation and/or cognitive function. In this work, a 10-day social defeat regimen was used to model psychosocial stress and the number and density of ionized calcium-binding adaptor molecule 1 (Iba1)-stained microglia was used to reveal brain immune activation in male Balb/C mice. The social defeat regimen did not cause observable microglial activation in dentate gyrus (DG) 24 h after the conclusion of the regimen. Microglial activation peaked in DG 24 h following a single 1 mg/kg intra-peritoneal LPS injection. At this time point, DG microglial activation was not evident providing 0.125 mg/kg or lower of LPS was used, this dose of LPS was, thus, regarded as the “sub-threshold” in this study. Twenty-four h after the conclusion of the defeat regimen, mice received a social interaction test to determine their defeat stress susceptibility and a “sub-threshold” LPS injection. DG microglial activation was observed in the defeat-stress susceptible, but not in the resilient, mice. Furthermore, the stress-susceptible mice showed impairment in object location and Y maze tasks 24 and 72 h after the “sub-threshold” LPS injection. These results suggest that psychosocial stress, when combined with a negligible peripheral infection, may induce long-lasting hippocampus-related memory deficits exclusively in subjects susceptible to psychosocial stresses.

Population control of resident and immigrant microglia by mitosis and apoptosis

DEFF Research Database (Denmark)

Wirenfeldt, Martin; Dissing-Olesen, Lasse; Babcock, Alicia

2007-01-01

microglia often occurred in clusters, some having recently incorporated bromodeoxyuridine, showing that proliferation had occurred. Annexin V labeling and staining for activated caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling showed that apoptotic mechanisms participate...... in dissolution of the microglial response. Using bone marrow chimeric mice, we found that the lesion-induced proliferative capacity of resident microglia superseded that of immigrant microglia, whereas lesion-induced kinetics of apoptosis were comparable. Microglial numbers and responses were severely reduced...... in bone marrow chimeric mice. These results broaden our understanding of the microglial response to neural damage by demonstrating that simultaneously occurring mitosis and apoptosis regulate expansion and reduction of both resident and immigrant microglial cell populations....

The Influence of Glutamate on Axonal Compound Action Potential In Vitro.

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Abouelela, Ahmed; Wieraszko, Andrzej

2016-01-01

Background  Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives  The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods  Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results  The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion  The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.

Vaccinium bracteatum Thunb. Exerts Anti-Inflammatory Activity by Inhibiting NF-?B Activation in BV-2 Microglial Cells

OpenAIRE

Kwon, Seung-Hwan; Ma, Shi-Xun; Ko, Yong-Hyun; Seo, Jee-Yeon; Lee, Bo-Ram; Lee, Taek Hwan; Kim, Sun Yeou; Lee, Seok-Yong; Jang, Choon-Gon

2016-01-01

This study was designed to evaluate the pharmacological effects of Vaccinium bracteatum Thunb. methanol extract (VBME) on microglial activation and to identify the underlying mechanisms of action of these effects. The anti-inflammatory properties of VBME were studied using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. We measured the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-?),...

Role of fractalkine/CX3CR1 interaction in light-induced photoreceptor degeneration through regulating retinal microglial activation and migration.

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Meng Zhang

Full Text Available BACKGROUND: Excessive exposure to light enhances the progression and severity of some human retinal degenerative diseases. While retinal microglia are likely to be important in neuron damage associated with these diseases, the relationship between photoreceptor damage and microglial activation remains poorly understood. Some recent studies have indicated that the chemokine fractalkine is involved in the pathogenesis of many neurodegenerative diseases. The present study was performed to investigate the cross-talk between injured photoreceptors and activated retinal microglia, focusing on the role of fractalkine and its receptor CX3CR1 in light-induced photoreceptor degeneration. METHODOLOGY/PRINCIPAL FINDINGS: Both in vivo and in vitro experiments were involved in the research. In vivo, Sprague-Dawley rats were exposed to blue light for 24 hours. In vitro, the co-culture of primary retinal microglia and a photoreceptor cell line (661W cell was exposed to blue light for five hours. Some cultures were pretreated by the addition of anti-CX3CR1 neutralizing antibody or recombinant fractalkine. Expression of fractalkine/CX3CR1 and inflammatory cytokines was detected by immunofluorescence, real-time PCR, Western immunoblot analysis, and ELISA assay. TUNEL method was used to detect cell apoptosis. In addition, chemotaxis assay was performed to evaluate the impact of soluble fractalkine on microglial migration. Our results showed that the expression of fractalkine that was significantly upregulated after exposure to light, located mainly at the photoreceptors. The extent of photoreceptor degeneration and microglial migration paralleled the increased level of fractalkine/CX3CR1. Compared with the control, the expression of inflammatory cytokines was significantly downregulated in the anti-CX3CR1 neutralizing antibody-treated group, and the number of photoreceptors was also well preserved. The addition of recombinant full-length fractalkine or soluble

Sleep deprivation aggravates median nerve injury-induced neuropathic pain and enhances microglial activation by suppressing melatonin secretion.

Science.gov (United States)

Huang, Chun-Ta; Chiang, Rayleigh Ping-Ying; Chen, Chih-Li; Tsai, Yi-Ju

2014-09-01

Sleep deprivation is common in patients with neuropathic pain, but the effect of sleep deprivation on pathological pain remains uncertain. This study investigated whether sleep deprivation aggravates neuropathic symptoms and enhances microglial activation in the cuneate nucleus (CN) in a median nerve chronic constriction injury (CCI) model. Also, we assessed if melatonin supplements during the sleep deprived period attenuates these effects. Rats were subjected to sleep deprivation for 3 days by the disc-on-water method either before or after CCI. In the melatonin treatment group, CCI rats received melatonin supplements at doses of 37.5, 75, 150, or 300 mg/kg during sleep deprivation. Melatonin was administered at 23:00 once a day. Male Sprague-Dawley rats, weighing 180-250 g (n = 190), were used. Seven days after CCI, behavioral testing was conducted, and immunohistochemistry, immunoblotting, and enzyme-linked immunosorbent assay were used for qualitative and quantitative analyses of microglial activation and measurements of proinflammatory cytokines. In rats who underwent post-CCI sleep deprivation, microglia were more profoundly activated and neuropathic pain was worse than those receiving pre-CCI sleep deprivation. During the sleep deprived period, serum melatonin levels were low over the 24-h period. Administration of melatonin to CCI rats with sleep deprivation significantly attenuated activation of microglia and development of neuropathic pain, and markedly decreased concentrations of proinflammatory cytokines. Sleep deprivation makes rats more vulnerable to nerve injury-induced neuropathic pain, probably because of associated lower melatonin levels. Melatonin supplements to restore a circadian variation in melatonin concentrations during the sleep deprived period could alleviate nerve injury-induced behavioral hypersensitivity. © 2014 Associated Professional Sleep Societies, LLC.

Atorvastatin prevents age-related and amyloid-β-induced microglial activation by blocking interferon-γ release from natural killer cells in the brain

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Clarke Rachael

2011-03-01

Full Text Available Abstract Background Microglial function is modulated by several factors reflecting the numerous receptors expressed on the cell surface, however endogenous factors which contribute to the age-related increase in microglial activation remain largely unknown. One possible factor which may contribute is interferon-γ (IFNγ. IFNγ has been shown to increase in the aged brain and potently activates microglia, although its endogenous cell source in the brain remains unidentified. Methods Male Wistar rats were used to assess the effect of age and amyloid-β (Aβ on NK cell infiltration into the brain. The effect of the anti-inflammatory compound, atorvastatin was also assessed under these conditions. We measured cytokine and chemokine (IFNγ, IL-2, monocyte chemoattractant protein-1 (MCP-1 and IFNγ-induced protein 10 kDa (IP-10, expression in the brain by appropriate methods. We also looked at NK cell markers, CD161, NKp30 and NKp46 using flow cytometry and western blot. Results Natural killer (NK cells are a major source of IFNγ in the periphery and here we report the presence of CD161+ NKp30+ cells and expression of CD161 and NKp46 in the brain of aged and Aβ-treated rats. Furthermore, we demonstrate that isolated CD161+ cells respond to interleukin-2 (IL-2 by releasing IFNγ. Atorvastatin, the HMG-CoA reductase inhibitor, attenuates the increase in CD161 and NKp46 observed in hippocampus of aged and Aβ-treated rats. This was paralleled by a decrease in IFNγ, markers of microglial activation and the chemokines, MCP-1 and IP-10 which are chemotactic for NK cells. Conclusions We propose that NK cells contribute to the age-related and Aβ-induced neuroinflammatory changes and demonstrate that these changes can be modulated by atorvastatin treatment.

Atorvastatin prevents age-related and amyloid-beta-induced microglial activation by blocking interferon-gamma release from natural killer cells in the brain

LENUS (Irish Health Repository)

Lyons, Anthony

2011-03-31

Abstract Background Microglial function is modulated by several factors reflecting the numerous receptors expressed on the cell surface, however endogenous factors which contribute to the age-related increase in microglial activation remain largely unknown. One possible factor which may contribute is interferon-γ (IFNγ). IFNγ has been shown to increase in the aged brain and potently activates microglia, although its endogenous cell source in the brain remains unidentified. Methods Male Wistar rats were used to assess the effect of age and amyloid-β (Aβ) on NK cell infiltration into the brain. The effect of the anti-inflammatory compound, atorvastatin was also assessed under these conditions. We measured cytokine and chemokine (IFNγ, IL-2, monocyte chemoattractant protein-1 (MCP-1) and IFNγ-induced protein 10 kDa (IP-10)), expression in the brain by appropriate methods. We also looked at NK cell markers, CD161, NKp30 and NKp46 using flow cytometry and western blot. Results Natural killer (NK) cells are a major source of IFNγ in the periphery and here we report the presence of CD161+ NKp30+ cells and expression of CD161 and NKp46 in the brain of aged and Aβ-treated rats. Furthermore, we demonstrate that isolated CD161+ cells respond to interleukin-2 (IL-2) by releasing IFNγ. Atorvastatin, the HMG-CoA reductase inhibitor, attenuates the increase in CD161 and NKp46 observed in hippocampus of aged and Aβ-treated rats. This was paralleled by a decrease in IFNγ, markers of microglial activation and the chemokines, MCP-1 and IP-10 which are chemotactic for NK cells. Conclusions We propose that NK cells contribute to the age-related and Aβ-induced neuroinflammatory changes and demonstrate that these changes can be modulated by atorvastatin treatment.

Edaravone, a Free Radical Scavenger, Mitigates Both Gray and White Matter Damages after Global Cerebral Ischemia in Rats

Science.gov (United States)

Kubo, Kozue; Nakao, Shinichi; Jomura, Sachiko; Sakamoto, Sachiyo; Miyamoto, Etsuko; Xu, Yan; Tomimoto, Hidekazu; Inada, Takefumi; Shingu, Koh

2012-01-01

Recent studies have shown that similar to cerebral gray matter (mainly composed of neuronal perikarya), white matter (composed of axons and glias) is vulnerable to ischemia. Edaravone, a free radical scavenger, has neuroprotective effects against focal cerebral ischemia even in humans. In this study, we investigated the time course and the severity of both gray and white matter damage following global cerebral ischemia by cardiac arrest, and examined whether edaravone protected the gray and the white matter. Male Sprague-Dawley rats were used. Global cerebral ischemia was induced by 5 minutes of cardiac arrest and resuscitation (CAR). Edaravone, 3 mg/kg, was administered intravenously either immediately or 60 minutes after CAR. The morphological damage was assessed by cresyl violet staining. The microtubule-associated protein 2 (a maker of neuronal perikarya and dendrites), the β amyloid precursor protein (the accumulation of which is a maker of axonal damage), and the ionized calcium binding adaptor molecule 1 (a marker of microglia) were stained for immunohistochemical analysis. Significant neuronal perikaryal damage and marked microglial activation were observed in the hippocampal CA1 region with little axonal damage one week after CAR. Two weeks after CAR, the perikaryal damage and microglial activation were unchanged, but obvious axonal damage occurred. Administration of edaravone 60 minutes after CAR significantly mitigated the perikaryal damage, the axonal damage, and the microglial activation. Our results show that axonal damage develops slower than perikaryal damage and that edaravone can protect both gray and white matter after CAR in rats. PMID:19410562

Perilesional edema in radiation necrosis reflects axonal degeneration

International Nuclear Information System (INIS)

Perez-Torres, Carlos J; Yuan, Liya; Schmidt, Robert E; Rich, Keith M; Ackerman, Joseph JH; Garbow, Joel R

2015-01-01

Recently, we characterized a Gamma Knife® radiation necrosis mouse model with various magnetic resonance imaging (MRI) protocols to identify biomarkers useful in differentiation from tumors. Though the irradiation was focal to one hemisphere, a contralateral injury was observed that appeared to be localized in the white matter only. Interestingly, this injury was identifiable in T2-weighted images, apparent diffusion coefficient (ADC), and magnetization transfer ratio (MTR) maps, but not on post-contrast T1-weighted images. This observation of edema independent of vascular changes is akin to the perilesional edema seen in clinical radiation necrosis. The pathology underlying the observed white-matter MRI changes was explored by performing immunohistochemistry for healthy axons and myelin. The presence of both healthy axons and myelin was reduced in the contralateral white-matter lesion. Based on our immunohistochemical findings, the contralateral white-matter injury is most likely due to axonal degeneration

Studies of axon-glial cell interactions and periaxonal K+ homeostasis--II. The effect of axonal stimulation, cholinergic agents and transport inhibitors on the resistance in series with the axon membrane.

Science.gov (United States)

Hassan, S; Lieberman, E M

1988-06-01

The small electrical resistance in series with the axon membrane is generally modeled as the intercellular pathway for current flow through the periaxonal glial (Schwann cell) sheath. The series resistance of the medial giant axon of the crayfish, Procambarus clarkii, was found to vary with conditions known to affect the electrical properties of the periaxonal glia. Series resistance was estimated from computer analysed voltage waveforms generated by axial wire-constant current and space clamp techniques. The average series resistance for all axons was 6.2 +/- 0.5 omega cm2 (n = 128). Values ranged between 1 and 30 omega cm2. The series resistance of axons with low resting membrane resistance (less than 1500 omega cm2) increased an average of 30% when stimulated for 45 s to 7 min (50 Hz) whereas the series resistance of high membrane resistance (greater than 1500 omega cm2) axons decreased an average of 10%. Carbachol (10(-7) M) caused the series resistance of low membrane resistance axons to decrease during stimulation but had no effect on high membrane resistance axons. d-Tubocurare (10(-8) M) caused the series resistance of high membrane resistance axons to increase during stimulation but had no effect on low membrane resistance axons. Bumetanide, a Na-K-Cl cotransport inhibitor and low [K+]o, prevented the stimulation-induced increase in series resistance of low membrane resistance axons but had no effect on the high membrane resistance axons. The results suggest that the series resistance of axons varies in response to the activity of the glial K+ uptake mechanisms stimulated by the appearance of K+ in the periaxonal space during action potential generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenotypic clustering: a novel method for microglial morphology analysis.

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Verdonk, Franck; Roux, Pascal; Flamant, Patricia; Fiette, Laurence; Bozza, Fernando A; Simard, Sébastien; Lemaire, Marc; Plaud, Benoit; Shorte, Spencer L; Sharshar, Tarek; Chrétien, Fabrice; Danckaert, Anne

2016-06-17

Microglial cells are tissue-resident macrophages of the central nervous system. They are extremely dynamic, sensitive to their microenvironment and present a characteristic complex and heterogeneous morphology and distribution within the brain tissue. Many experimental clues highlight a strong link between their morphology and their function in response to aggression. However, due to their complex "dendritic-like" aspect that constitutes the major pool of murine microglial cells and their dense network, precise and powerful morphological studies are not easy to realize and complicate correlation with molecular or clinical parameters. Using the knock-in mouse model CX3CR1(GFP/+), we developed a 3D automated confocal tissue imaging system coupled with morphological modelling of many thousands of microglial cells revealing precise and quantitative assessment of major cell features: cell density, cell body area, cytoplasm area and number of primary, secondary and tertiary processes. We determined two morphological criteria that are the complexity index (CI) and the covered environment area (CEA) allowing an innovative approach lying in (i) an accurate and objective study of morphological changes in healthy or pathological condition, (ii) an in situ mapping of the microglial distribution in different neuroanatomical regions and (iii) a study of the clustering of numerous cells, allowing us to discriminate different sub-populations. Our results on more than 20,000 cells by condition confirm at baseline a regional heterogeneity of the microglial distribution and phenotype that persists after induction of neuroinflammation by systemic injection of lipopolysaccharide (LPS). Using clustering analysis, we highlight that, at resting state, microglial cells are distributed in four microglial sub-populations defined by their CI and CEA with a regional pattern and a specific behaviour after challenge. Our results counteract the classical view of a homogenous regional resting

Cofilin Knockdown Attenuates Hemorrhagic Brain Injury-induced Oxidative Stress and Microglial Activation in Mice.

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Alhadidi, Qasim; Nash, Kevin M; Alaqel, Saleh; Sayeed, Muhammad Shahdaat Bin; Shah, Zahoor A

2018-05-08

Intracerebral hemorrhage (ICH) resulting from the rupture of the blood vessels in the brain is associated with significantly higher mortality and morbidity. Clinical studies focused on alleviating the primary injury, hematoma formation and expansion, were largely ineffective, suggesting that secondary injury-induced inflammation and the formation of reactive species also contribute to the overall injury process. In this study, we explored the effects of cofilin knockdown in a mouse model of ICH. Animals given stereotaxic injections of cofilin siRNA, 72-h prior to induction of ICH by collagenase injection within the area of siRNA administration showed significantly decreased cofilin expression levels and lower hemorrhage volume and edema, and the animals performed significantly better in neurobehavioral tasks i.e., rotarod, grip strength and neurologic deficit scores. Cofilin siRNA knocked-down mice had reduced ICH-induced DNA fragmentation, blood-brain barrier disruption and microglial activation, with a concomitant increase in astrocyte activation. Increased expression of pro-survival proteins and decreased markers of oxidative stress were also observed in cofilin siRNA-treated mice possibly due to the reduced levels of cofilin. Our results suggest that cofilin plays a major role in ICH-induced secondary injury, and could become a potential therapeutic target. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Transcranial light-emitting diode therapy for neuropsychological improvement after traumatic brain injury: a new perspective for diffuse axonal lesion management

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Santos JG

2018-04-01

Full Text Available João Gustavo Rocha Peixoto dos Santos, Wellingson Silva Paiva, Manoel Jacobsen Teixeira Department of Neurological Surgery, University of São Paulo School of Medicine, São Paulo, Brazil Abstract: The cost of traumatic brain injury (TBI for public health policies is undeniable today. Even patients who suffer from mild TBI may persist with cognitive symptoms weeks after the accident. Most of them show no lesion in computed tomography or conventional magnetic resonance imaging, but microstructural white matter abnormalities (diffuse axonal lesion can be found in diffusion tensor imaging. Different brain networks work together to form an important part of the cognition process, and they can be affected by TBI. The default mode network (DMN plays an important central role in normal brain activities, presenting greater relative deactivation during more cognitively demanding tasks. After deactivation, it allows a distinct network to activate. This network (the central executive network acts mainly during tasks involving executive functions. The salience network is another network necessary for normal executive function, and its activation leads to deactivation of the DMN. The use of red or near-infrared (NIR light to stimulate or regenerate tissue is known as photobiomodulation. It was discovered that NIR (wavelength 800–900 nm and red (wavelength 600 nm light-emitting diodes (LEDs are able to penetrate through scalp and skull and have the potential to improve the subnormal, cellular activity of compromised brain tissue. Based on this, different experimental and clinical studies were done to test LED therapy for TBI, and promising results were found. It leads us to consider developing different approaches to maximize the positive effects of this therapy and improve the quality of life of TBI patients. Keywords: traumatic brain injuries, diffuse axonal injury, low-level light therapy, neurologic manifestations, post-concussion syndrome, quality

Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

International Nuclear Information System (INIS)

Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.; Svoboda, Kurt R.

2015-01-01

Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner. �

Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

Energy Technology Data Exchange (ETDEWEB)

Menelaou, Evdokia; Paul, Latoya T. [Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 (United States); Perera, Surangi N. [Joseph J. Zilber School of Public Health, University of Wisconsin — Milwaukee, Milwaukee, WI 53205 (United States); Svoboda, Kurt R., E-mail: svobodak@uwm.edu [Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 (United States); Joseph J. Zilber School of Public Health, University of Wisconsin — Milwaukee, Milwaukee, WI 53205 (United States)

2015-04-01

Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner. �

Chondroitin-4-sulfation negatively regulates axonal guidance and growth

Science.gov (United States)

Wang, Hang; Katagiri, Yasuhiro; McCann, Thomas E.; Unsworth, Edward; Goldsmith, Paul; Yu, Zu-Xi; Tan, Fei; Santiago, Lizzie; Mills, Edward M.; Wang, Yu; Symes, Aviva J.; Geller, Herbert M.

2008-01-01

Summary Glycosaminoglycan (GAG) side chains endow extracellular matrix proteoglycans with diversity and complexity based upon the length, composition, and charge distribution of the polysaccharide chain. Using cultured primary neurons, we show that specific sulfation in the GAG chains of chondroitin sulfate (CS) mediates neuronal guidance cues and axonal growth inhibition. Chondroitin-4-sulfate (CS-A), but not chondroitin-6-sulfate (CS-C), exhibits a strong negative guidance cue to mouse cerebellar granule neurons. Enzymatic and gene-based manipulations of 4-sulfation in the GAG side chains alter their ability to direct growing axons. Furthermore, 4-sulfated CS GAG chains are rapidly and significantly increased in regions that do not support axonal regeneration proximal to spinal cord lesions in mice. Thus, our findings provide the evidence showing that specific sulfation along the carbohydrate backbone carries instructions to regulate neuronal function. PMID:18768934

Anthocyanins Downregulate Lipopolysaccharide-Induced Inflammatory Responses in BV2 Microglial Cells by Suppressing the NF-κB and Akt/MAPKs Signaling Pathways

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Yung Hyun Choi

2013-01-01

Full Text Available Anthocyanins are naturally occurring polyphenols that impart bright color to fruits, vegetables and plants and have a variety of protective properties, which have generally been attributed to their antioxidant capacity. However, little is known about the molecular mechanisms underlying anti-inflammatory effects of anthocyanins related to neurodegenerative diseases. Therefore, we determined whether anthocyanins isolated from black soybean seed coats would inhibit pro-inflammatory mediators and cytokines in lipopolysaccharide (LPS-stimulated murine BV2 microglial cells. Our results showed that anthocyanins significantly inhibited LPS-induced pro-inflammatory mediators, such as nitric oxide (NO and prostaglandin E2, and pro-inflammatory cytokines including tumor necrosis factor (TNF-α and interleukin (IL-1β, without significant cytotoxicity. Anthocyanins also downregulated excessive expression of inducible NO synthase, cyclooxygenase-2, TNF-α, and IL-1β in LPS-stimulated BV2 cells. Moreover, anthocyanins inhibited nuclear translocation of nuclear factor-kappa B (NF-κB by reducing inhibitor of NF-κB alpha degradation as well as phosphorylating extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and Akt. These findings suggest that anthocyanins may offer substantial therapeutic potential for treating inflammatory and neurodegenerative diseases accompanied by microglial activation.

Microglial Cells Prevent Hemorrhage in Neonatal Focal Arterial Stroke

OpenAIRE

Fernández-López, David; Faustino, Joel; Klibanov, Alexander L.; Derugin, Nikita; Blanchard, Elodie; Simon, Franziska; Leib, Stephen L.; Vexler, Zinaida S.

2016-01-01

Perinatal stroke leads to significant morbidity and long-term neurological and cognitive deficits. The pathophysiological mechanisms of brain damage depend on brain maturation at the time of stroke. To understand whether microglial cells limit injury after neonatal stroke by preserving neurovascular integrity, we subjected postnatal day 7 (P7) rats depleted of microglial cells, rats with inhibited microglial TGFbr2/ALK5 signaling, and corresponding controls, to transient middle cerebral arter...

Alpha-synuclein mutations impair axonal regeneration in models of Parkinson´s disease

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Lars eTönges

2014-09-01

Full Text Available The dopaminergic (DAergic nigrostriatal tract has an intrinsic regenerative capacity which can be impaired in Parkinson’s disease (PD. Alpha-synuclein (aSyn is a major pathogenic component in PD but its impact on DAergic axonal regeneration is largely unknown. In this study, we expressed pathogenic variants of human aSyn by means of recombinant adeno-associated viral vectors in experimental paradigms of DAergic regeneration. In a scratch lesion model in vitro, both aSyn(A30P and aSyn(A53T significantly reduced DAergic neurite regeneration and induced loss of TH-immunopositive cells while aSyn(WT showed only minor cellular neurotoxic effects. The striatal density of TH-immunopositive axons in the striatal 6-OHDA lesion mouse model was attenuated only by aSyn(A30P. However, striatal expression levels of the regeneration marker GAP-43 in TH-immunopositive fibers were reduced by both aSyn(A30P and aSyn(A53T, but not by aSyn(WT which was associated with an activation of the ROCK signaling pathway. Nigral DAergic cell loss was only mildly enhanced by additional overexpression of aSyn variants. Our findings indicate that mutations of aSyn have a strong impact on the regenerative capacity of DAergic neurons, which may contribute to their pathogenic effects.

REGENERATIVE GROWTH OF CORTICOSPINAL TRACT AXONS VIA THE VENTRAL COLUMN AFTER SPINAL CORD INJURY IN MICE

OpenAIRE

Steward, Oswald; Zheng, Binhai; Tessier-Lavigne, Marc; Hofstadter, Maura; Sharp, Kelli; Yee, Kelly Matsudaira

2008-01-01

Studies that have assessed regeneration of corticospinal tract (CST) axons in mice following genetic modifications or other treatments have tacitly assumed that there is little if any regeneration of CST axons in normal mice in the absence of some intervention. Here, we document a previously unrecognized capability for regenerative growth of CST axons in normal mice that involves growth past the lesion via the ventral column. Mice received dorsal hemisection injuries at thoracic level 6–7, wh...

Activation of microglial cells triggers a release of brain-derived neurotrophic factor (BDNF) inducing their proliferation in an adenosine A2A receptor-dependent manner: A2A receptor blockade prevents BDNF release and proliferation of microglia

Science.gov (United States)

2013-01-01

Background Brain-derived neurotrophic factor (BDNF) has been shown to control microglial responses in neuropathic pain. Since adenosine A2A receptors (A2ARs) control neuroinflammation, as well as the production and function of BDNF, we tested to see if A2AR controls the microglia-dependent secretion of BDNF and the proliferation of microglial cells, a crucial event in neuroinflammation. Methods Murine N9 microglial cells were challenged with lipopolysaccharide (LPS, 100 ng/mL) in the absence or in the presence of the A2AR antagonist, SCH58261 (50 nM), as well as other modulators of A2AR signaling. The BDNF cellular content and secretion were quantified by Western blotting and ELISA, A2AR density was probed by Western blotting and immunocytochemistry and cell proliferation was assessed by BrdU incorporation. Additionally, the A2AR modulation of LPS-driven cell proliferation was also tested in primary cultures of mouse microglia. Results LPS induced time-dependent changes of the intra- and extracellular levels of BDNF and increased microglial proliferation. The maximal LPS-induced BDNF release was time-coincident with an LPS-induced increase of the A2AR density. Notably, removing endogenous extracellular adenosine or blocking A2AR prevented the LPS-mediated increase of both BDNF secretion and proliferation, as well as exogenous BDNF-induced proliferation. Conclusions We conclude that A2AR activation plays a mandatory role controlling the release of BDNF from activated microglia, as well as the autocrine/paracrine proliferative role of BDNF. PMID:23363775

Lipoprotein Lipase Maintains Microglial Innate Immunity in Obesity

NARCIS (Netherlands)

Gao, Yuanqing; Vidal-Itriago, Andrés; Kalsbeek, Martin J; Layritz, Clarita; García-Cáceres, Cristina; Tom, Robby Zachariah; Eichmann, Thomas O; Vaz, Frédéric M; Houtkooper, Riekelt H; van der Wel, Nicole; Verhoeven, Arthur J; Yan, Jie; Kalsbeek, A.; Eckel, Robert H; Hofmann, Susanna M; Yi, Chun-Xia

2017-01-01

Consumption of a hypercaloric diet upregulates microglial innate immune reactivity along with a higher expression of lipoprotein lipase (Lpl) within the reactive microglia in the mouse brain. Here, we show that knockdown of the Lpl gene specifically in microglia resulted in deficient microglial

Acute ethanol exposure inhibits silencing of cerebellar Golgi cell firing induced by granule cell axon input

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Paolo eBotta

2014-02-01

Full Text Available Golgi cells (GoCs are specialized interneurons that provide inhibitory input to granule cells in the cerebellar cortex. GoCs are pacemaker neurons that spontaneously fire action potentials, triggering spontaneous inhibitory postsynaptic currents in granule cells and also contributing to the generation tonic GABAA receptor-mediated currents in granule cells. In turn, granule cell axons provide feedback glutamatergic input to GoCs. It has been shown that high frequency stimulation of granule cell axons induces a transient pause in GoC firing in a type 2-metabotropic glutamate receptor (mGluR2-dependent manner. Here, we investigated the effect ethanol on the pause of GoC firing induced by high frequency stimulation of granule cell axons. GoC electrophysiological recordings were performed in parasagittal cerebellar vermis slices from postnatal day 23 to 26 rats. Loose-patch cell-attached recordings revealed that ethanol (40 mM reversibly decreases the pause duration. An antagonist of mGluR2 reduced the pause duration but did not affect the effect of ethanol. Whole-cell voltage-clamp recordings showed that currents evoked by an mGluR2 agonist were not significantly affected by ethanol. Perforated-patch experiments in which hyperpolarizing and depolarizing currents were injected into GoCs demonstrated that there is an inverse relationship between spontaneous firing and pause duration. Slight inhibition of the Na+/K+ pump mimicked the effect of ethanol on pause duration. In conclusion, ethanol reduces the granule cell axon-mediated feedback mechanism by reducing the input responsiveness of GoCs. This would result in a transient increase of GABAA receptor-mediated inhibition of granule cells, limiting information flow at the input stage of the cerebellar cortex.

Dendrosomatic Sonic Hedgehog Signaling in Hippocampal Neurons Regulates Axon Elongation

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Petralia, Ronald S.; Ott, Carolyn; Wang, Ya-Xian; Lippincott-Schwartz, Jennifer; Mattson, Mark P.

2015-01-01

The presence of Sonic Hedgehog (Shh) and its signaling components in the neurons of the hippocampus raises a question about what role the Shh signaling pathway may play in these neurons. We show here that activation of the Shh signaling pathway stimulates axon elongation in rat hippocampal neurons. This Shh-induced effect depends on the pathway transducer Smoothened (Smo) and the transcription factor Gli1. The axon itself does not respond directly to Shh; instead, the Shh signal transduction originates from the somatodendritic region of the neurons and occurs in neurons with and without detectable primary cilia. Upon Shh stimulation, Smo localization to dendrites increases significantly. Shh pathway activation results in increased levels of profilin1 (Pfn1), an actin-binding protein. Mutations in Pfn1's actin-binding sites or reduction of Pfn1 eliminate the Shh-induced axon elongation. These findings indicate that Shh can regulate axon growth, which may be critical for development of hippocampal neurons. SIGNIFICANCE STATEMENT Although numerous signaling mechanisms have been identified that act directly on axons to regulate their outgrowth, it is not known whether signals transduced in dendrites may also affect axon outgrowth. We describe here a transcellular signaling pathway in embryonic hippocampal neurons in which activation of Sonic Hedgehog (Shh) receptors in dendrites stimulates axon growth. The pathway involves the dendritic-membrane-associated Shh signal transducer Smoothened (Smo) and the transcription factor Gli, which induces the expression of the gene encoding the actin-binding protein profilin 1. Our findings suggest scenarios in which stimulation of Shh in dendrites results in accelerated outgrowth of the axon, which therefore reaches its presumptive postsynaptic target cell more quickly. By this mechanism, Shh may play critical roles in the development of hippocampal neuronal circuits. PMID:26658865

Retinoic acid signaling in axonal regeneration

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Radhika ePuttagunta

2012-01-01

Full Text Available Following an acute central nervous system injury, axonal regeneration and functional recovery are extremely limited. This is due to an extrinsic inhibitory growth environment and the lack of intrinsic growth competence. Retinoic acid (RA signaling, essential in developmental dorsoventral patterning and specification of spinal motor neurons, has been shown through its receptor, the transcription factor RA receptor β2 (RARß2, to induce axonal regeneration following spinal cord injury (SCI. Recently, it has been shown that in dorsal root ganglia neurons, cAMP levels were greatly increased by lentiviral RARβ2 expression and contributed to neurite outgrowth. Moreover, RARβ agonists, in cerebellar granule neurons and in the brain in vivo, induced phosphoinositide 3-kinase dependent phosphorylation of AKT that was involved in RARβ-dependent neurite outgrowth. More recently, RA-RARß pathways were shown to directly transcriptionally repress a member of the inhibitory Nogo receptor complex, Lingo-1, under an axonal growth inhibitory environment in vitro as well as following spinal injury in vivo. This perspective focuses on these newly discovered molecular mechanisms and future directions in the field.

Trans-caryophyllene inhibits amyloid β (Aβ) oligomer-induced neuroinflammation in BV-2 microglial cells.

Science.gov (United States)

Hu, Yawei; Zeng, Ziling; Wang, Baojie; Guo, Shougang

2017-10-01

Amyloid β (Aβ) is the major component of senile plaques (SP) in the brains of Alzheimer's disease (AD) patients, and serves as an inflammatory stimulus for microglia. Trans-caryophyllene (TC), a major component in the essential oils derived from various species of medicinal plants, has displayed its neuro-protective effects in previous studies. However, whether TC has a protective role in AD remains unknown. In this study, the effects of TC on Aβ 1-42 -induced neuro-inflammation were investigated. We found that TC reduced the release of LDH in BV-2 microglial cells treated with Aβ 1-42 . In addition, pretreatment of BV2 microglia with TC at concentrations of 10, 25, and 50μM prior to Aβ stimulation led to significant inhibition of nitric oxide (NO) and prostaglandin E2 (PGE2) production, expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and secretion of pro-inflammatory cytokines. Notably, our results indicate that TC remarkably attenuated Aβ 1-42 -activated overexpression of toll-like receptor 4 (TLR4). We further demonstrated that TC markedly reversed Aβ 1-42 -induced phosphorylation and degradation of IκBα, nuclear translocation of p65, and NF-κB transcriptional activity. These findings suggest that TC may have therapeutic potential for the treatment of AD. Copyright © 2017. Published by Elsevier B.V.

Sulforaphane Inhibits Lipopolysaccharide-Induced Inflammation, Cytotoxicity, Oxidative Stress, and miR-155 Expression and Switches to Mox Phenotype through Activating Extracellular Signal-Regulated Kinase 1/2-Nuclear Factor Erythroid 2-Related Factor 2/Antioxidant Response Element Pathway in Murine Microglial Cells.

Science.gov (United States)

Eren, Erden; Tufekci, Kemal Ugur; Isci, Kamer Burak; Tastan, Bora; Genc, Kursad; Genc, Sermin

2018-01-01

Sulforaphane (SFN) is a natural product with cytoprotective, anti-inflammatory, and antioxidant effects. In this study, we evaluated the mechanisms of its effects on lipopolysaccharide (LPS)-induced cell death, inflammation, oxidative stress, and polarization in murine microglia. We found that SFN protects N9 microglial cells upon LPS-induced cell death and suppresses LPS-induced levels of secreted pro-inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6. SFN is also a potent inducer of redox sensitive transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2), which is responsible for the transcription of antioxidant, cytoprotective, and anti-inflammatory genes. SFN induced translocation of Nrf2 to the nucleus via extracellular signal-regulated kinase 1/2 (ERK1/2) pathway activation. siRNA-mediated knockdown study showed that the effects of SFN on LPS-induced reactive oxygen species, reactive nitrogen species, and pro-inflammatory cytokine production and cell death are partly Nrf2 dependent. Mox phenotype is a novel microglial phenotype that has roles in oxidative stress responses. Our results suggested that SFN induced the Mox phenotype in murine microglia through Nrf2 pathway. SFN also alleviated LPS-induced expression of inflammatory microRNA, miR-155. Finally, SFN inhibits microglia-mediated neurotoxicity as demonstrated by conditioned medium and co-culture experiments. In conclusion, SFN exerts protective effects on microglia and modulates the microglial activation state.

SCM-198 inhibits microglial overactivation and attenuates Aβ(1-40)-induced cognitive impairments in rats via JNK and NF-кB pathways.

Science.gov (United States)

Hong, Zhen-Yi; Shi, Xue-Ru; Zhu, Kai; Wu, Ting-Ting; Zhu, Yi-Zhun

2014-08-19

Neuroinflammation mediated by overactivated microglia plays a key role in many neurodegenerative diseases, including Alzheimer's disease (AD). In this study, we investigated for the first time the anti-neuroinflammatory effects and possible mechanisms of SCM-198 (an alkaloid extracted from Herbaleonuri), which was previously found highly cardioprotective, both in vitro and in vivo. For in vitro experiments, lipopolysaccharide (LPS) or β-amyloid(1-40) (Aβ(1-40)) was applied to induce microglial overactivation. Proinflammatory mediators were measured and activations of NF-κB and mitogen-activated protein kinases' (MAPKs) pathways were investigated. Further protective effect of SCM-198 was evaluated in microglia-neuron co-culture assay and Sprague-Dawley (SD) rats intrahippocampally-injected with Aβ(1-40). SCM-198 reduced expressions of nitric oxide (NO), TNF-α, IL-1β and IL-6 possibly via, at least partially, inhibiting c-Jun N-terminal kinase (JNK) and NF-κB signaling pathways in microglia. Co-culture assay showed that activated microglia pretreated with SCM-198 led to less neuron loss and decreased phosphorylation of tau and extracellular signal-regulated kinase (ERK) in neurons. Besides, SCM-198 also directly protected against Aβ(1-40)-induced neuronal death and lactate dehydrogenase (LDH) release in primary cortical neurons. For in vivo studies, SCM-198 significantly enhanced cognitive performances of rats 12 days after intrahippocampal injections of aged Aβ(1-40) peptides in the Morris water maze (MWM), accompanied by less hippocampal microglial activation, decreased synaptophysin loss and phosphorylation of ERK and tau. Co-administration of donepezil and SCM-198 resulted in a slight cognitive improvement in SD rats 50 days after intrahippocampal injections of aged Aβ(1-40) peptides as compared to only donepezil or SCM-198 treated group. Our findings are the first to report that SCM-198 has considerable anti-neuroinflammatory effects on inhibiting

Retrograde axonal transport of 125I-nerve growth factor in rat ileal mesenteric nerves. Effect of streptozocin diabetes

International Nuclear Information System (INIS)

Schmidt, R.E.; Plurad, S.B.; Saffitz, J.E.; Grabau, G.G.; Yip, H.K.

1985-01-01

The retrograde axonal transport of intravenously (i.v.) administered 125 I-nerve growth factor ( 125 I-NGF) was examined in mesenteric nerves innervating the small bowel of rats with streptozocin (STZ) diabetes using methods described in detail in the companion article. The accumulation of 125 I-NGF distal to a ligature on the ileal mesenteric nerves of diabetic animals was 30-40% less than in control animals. The inhibition of accumulation of 125 I-NGF in diabetic animals was greater at a ligature tied 2 h after i.v. administration than at a ligature tied after 14 h, which suggests that the diabetic animals may have a lag in initiation of NGF transport in the terminal axon or retardation of transport at some site along the axon. The 125 I-NGF transport defect was observed as early as 3 days after the induction of diabetes, a time before the development of structural axonal lesions, and did not worsen at later times when dystrophic axonopathy is present. Both the ileal mesenteric nerves, which eventually develop dystrophic axonopathy in experimental diabetes, and the jejunal mesenteric nerves, which never develop comparable structural alterations, showed similar 125 I-NGF transport deficits, suggesting that the existence of the transport abnormality does not predict the eventual development of dystrophic axonal lesions. Autoradiographic localization of 125 I-NGF in the ileal mesenteric nerves of animals that had been diabetic for 11-13 mo demonstrated decreased amounts of 125 I-NGF in transit in unligated paravascular nerve fascicles. There was, however, no evidence for focal retardation of transported 125 I-NGF at the sites of dystrophic axonal lesions

Regulatory Effects of Fisetin on Microglial Activation

OpenAIRE

Chuang, Jing-Yuan; Chang, Pei-Chun; Shen, Yi-Chun; Lin, Chingju; Tsai, Cheng-Fang; Chen, Jia-Hong; Yeh, Wei-Lan; Wu, Ling-Hsuan; Lin, Hsiao-Yun; Liu, Yu-Shu; Lu, Dah-Yuu

2014-01-01

Increasing evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play a key role in neurodegeneration. Fisetin, a plant flavonol commonly found in fruits and vegetables, is frequently added to nutritional supplements due to its antioxidant properties. In the present study, treatment with fisetin inhibited microglial cell migration and ROS (reactive oxygen species) production. Treatment with fisetin also effectively inhibited LPS...

Characterization of patients with head trauma and traumatic axonal injury

International Nuclear Information System (INIS)

Mosquera Betancourt, Dra.C. Gretel; Van Duc, Dr. Hanh; Casares Delgado, Dr. Jorge Alejandro; Hernández González, Dr. Erick Héctor

2016-01-01

Background: traumatic axonal injury is characterized by multifocal lesions, consequences of primary, secondary and tertiary damage which is able to cause varying degrees of disability. Objective: to characterize patients with traumatic axonal injury. Methods: a cross-sectional analytical study was conducted from January 2014 to December 2015. The target population was composed of 35 patients over age 18 whose diagnosis was traumatic axonal injury type I and IV of the Marshall computed tomographic (CT) classification. With the data collected from medical records revisions and direct observation, a database was created in SPSS for its processing through univariate and multivariate techniques. Results: male patients between 18 and 30 years old without bad habits prevailed. Most of the patients survived and death was associated with the presence of severe traumatic axonal injury, Marshall computed tomographic (CT) classification degree III, complications and presence of trauma in thorax, abdomen and cervical spine. Conclusions: diagnosis of traumatic axonal injury is based on the clinical radiological correlation based on images from tomography and it is confirmed by Magnetic resonance imaging (MRI). Histological study shows injuries that are not demonstrated in the most advanced radiological studies. Its prevention is the most fundamental base in medical assistance, followed by neurocritical attention oriented by neuromonitoring. (author)

Anti-Inflammatory Strategy for M2 Microglial Polarization Using Retinoic Acid-Loaded Nanoparticles

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Marta Machado-Pereira

2017-01-01

Full Text Available Inflammatory mechanisms triggered by microglial cells are involved in the pathophysiology of several brain disorders, hindering repair. Herein, we propose the use of retinoic acid-loaded polymeric nanoparticles (RA-NP as a means to modulate microglia response towards an anti-inflammatory and neuroprotective phenotype (M2. RA-NP were first confirmed to be internalized by N9 microglial cells; nanoparticles did not affect cell survival at concentrations below 100 μg/mL. Then, immunocytochemical studies were performed to assess the expression of pro- and anti-inflammatory mediators. Our results show that RA-NP inhibited LPS-induced release of nitric oxide and the expression of inducible nitric oxide synthase and promoted arginase-1 and interleukin-4 production. Additionally, RA-NP induced a ramified microglia morphology (indicative of M2 state, promoting tissue viability, particularly neuronal survival, and restored the expression of postsynaptic protein-95 in organotypic hippocampal slice cultures exposed to an inflammatory challenge. RA-NP also proved to be more efficient than the free equivalent RA concentration. Altogether, our data indicate that RA-NP may be envisioned as a promising therapeutic agent for brain inflammatory diseases.

A preconditioning nerve lesion inhibits mechanical pain hypersensitivity following subsequent neuropathic injury

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Wu Ann

2011-01-01

Full Text Available Abstract Background A preconditioning stimulus can trigger a neuroprotective phenotype in the nervous system - a preconditioning nerve lesion causes a significant increase in axonal regeneration, and cerebral preconditioning protects against subsequent ischemia. We hypothesized that a preconditioning nerve lesion induces gene/protein modifications, neuronal changes, and immune activation that may affect pain sensation following subsequent nerve injury. We examined whether a preconditioning lesion affects neuropathic pain and neuroinflammation after peripheral nerve injury. Results We found that a preconditioning crush injury to a terminal branch of the sciatic nerve seven days before partial ligation of the sciatic nerve (PSNL; a model of neuropathic pain induced a significant attenuation of pain hypersensitivity, particularly mechanical allodynia. A preconditioning lesion of the tibial nerve induced a long-term significant increase in paw-withdrawal threshold to mechanical stimuli and paw-withdrawal latency to thermal stimuli, after PSNL. A preconditioning lesion of the common peroneal induced a smaller but significant short-term increase in paw-withdrawal threshold to mechanical stimuli, after PSNL. There was no difference between preconditioned and unconditioned animals in neuronal damage and macrophage and T-cell infiltration into the dorsal root ganglia (DRGs or in astrocyte and microglia activation in the spinal dorsal and ventral horns. Conclusions These results suggest that prior exposure to a mild nerve lesion protects against adverse effects of subsequent neuropathic injury, and that this conditioning-induced inhibition of pain hypersensitivity is not dependent on neuroinflammation in DRGs and spinal cord. Identifying the underlying mechanisms may have important implications for the understanding of neuropathic pain due to nerve injury.

P2Y12R-Dependent Translocation Mechanisms Gate the Changing Microglial Landscape

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Ukpong B. Eyo

2018-04-01

Full Text Available Summary: Microglia are an exquisitely tiled and self-contained population in the CNS that do not receive contributions from circulating monocytes in the periphery. While microglia are long-lived cells, the extent to which their cell bodies are fixed and the molecular mechanisms by which the microglial landscape is regulated have not been determined. Using chronic in vivo two-photon imaging to follow the microglial population in young adult mice, we document a daily rearrangement of the microglial landscape. Furthermore, we show that the microglial landscape can be modulated by severe seizures, acute injury, and sensory deprivation. Finally, we demonstrate a critical role for microglial P2Y12Rs in regulating the microglial landscape through cellular translocation independent of proliferation. These findings suggest that microglial patrol the CNS through both process motility and soma translocation. : Using a chronic in vivo imaging approach, Eyo et al. show that the physical positions of brain microglia change daily and that these changes increase following certain experimental manipulations. The mechanism underlying these changes involves cell translocation controlled by microglial-specific P2Y12 receptors. Keywords: microglia, P2Y12, seizures, epilepsy, whisker trimming, microglial landscape, two photon chronic imaging

Variable laterality of corticospinal tract axons that regenerate after spinal cord injury as a result of PTEN deletion or knock-down

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Willenberg, Rafer; Zukor, Katherine; Liu, Kai; He, Zhigang; Steward, Oswald

2016-01-01

Corticospinal tract (CST) axons from one hemisphere normally extend and terminate predominantly in the contralateral spinal cord. We previously showed that deleting PTEN in the sensorimotor cortex enables CST axons to regenerate after spinal cord injury and that some regenerating axons extend along the “wrong” side. Here, we characterize the degree of specificity of regrowth in terms of laterality. PTEN was selectively deleted via cortical AAV-Cre injections in neonatal PTEN-floxed mice. As adults, mice received dorsal hemisection injuries at T12 or complete crush injuries at T9. CST axons from one hemisphere were traced by unilateral BDA injections in PTEN-deleted mice with spinal cord injury and in non-injured PTEN-floxed mice that had not received AAV-Cre. In non-injured mice, 97.9 ± 0.7% of BDA-labeled axons in white matter and 88.5 ± 1.0% of BDA-labeled axons in grey matter were contralateral to the cortex of origin. In contrast, laterality of CST axons that extended past a lesion due to PTEN deletion varied across animals. In some cases, regenerated axons extended predominantly on the ipsilateral side, in other cases, axons extended predominantly contralaterally, and in others, axons were similar in numbers on both sides. Similar results were seen in analyses of cases from previous studies using shRNA-mediated PTEN knock-down. These results indicate that CST axons that extend past a lesion due to PTEN deletion or knock-down do not maintain the contralateral rule of the non-injured CST, highlighting one aspect for how resultant circuitry from regenerating axons may differ from that of the uninjured CST. PMID:26878190

Slowing of axonal regeneration is correlated with increased axonal viscosity during aging

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Heidemann Steven R

2010-10-01

Full Text Available Abstract Background As we age, the speed of axonal regeneration declines. At the biophysical level, why this occurs is not well understood. Results To investigate we first measured the rate of axonal elongation of sensory neurons cultured from neonatal and adult rats. We found that neonatal axons grew 40% faster than adult axons (11.5 µm/hour vs. 8.2 µm/hour. To determine how the mechanical properties of axons change during maturation, we used force calibrated towing needles to measure the viscosity (stiffness and strength of substrate adhesion of neonatal and adult sensory axons. We found no significant difference in the strength of adhesions, but did find that adult axons were 3 times intrinsically stiffer than neonatal axons. Conclusions Taken together, our results suggest decreasing axonal stiffness may be part of an effective strategy to accelerate the regeneration of axons in the adult peripheral nervous system.

Inhibition of lipopolysaccharide-induced proinflammatory responses by Buddleja officinalis extract in BV-2 microglial cells via negative regulation of NF-kB and ERK1/2 signaling.

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Oh, Won-Jun; Jung, Uhee; Eom, Hyun-Soo; Shin, Hee-June; Park, Hae-Ran

2013-07-31

Buddleja officinalis has been traditionally used in the supportive treatment of inflammatory and neuronal diseases in Korea and China. Although several reports have shown the anti-inflammatory effects of Buddleja officinalis, the anti-neuroinflammatory effect has remained unclear. In this study, we aimed to investigate the inhibitory effects of flower buds of B. officinalis Maximowicz water extract (BOWE) on LPS-induced inflammatory processes in BV-2 microglial cells. BOWE dose-dependently inhibited the production of nitric oxide as well as iNOS mRNA expression. Moreover, BOWE prevented IL-1β and IL-6 mRNA expression. However, BOWE had no effect on LPS-induced COX-2 or TNF-a mRNA expression. The extract also had no effect on LPS-stimulated p38 MAPK, JNK, and c-Jun phosphorylation, whereas ERK1/2 phosphorylation was strongly inhibited by BOWE. BOWE also inhibited the LPS-induced degradation of IkB-α, and LPS-induced phosphorylation of p65 NF-kB protein. These data indicate that BOWE inhibited the nitric oxide production and pro-inflammatory gene expression in BV-2 microglial cells, possibly through a negative regulation of the NF-kB and ERK1/2 pathways. Further identification of the direct target molecule(s) of BOWE is required to support its use as an anti-neuroinflammatory agent against the neurodegenerative disorders.

Inhibition of Lipopolysaccharide-Induced Proinflammatory Responses by Buddleja officinalis Extract in BV-2 Microglial Cells via Negative Regulation of NF-kB and ERK1/2 Signaling

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Hae-Ran Park

2013-07-01

Full Text Available Buddleja officinalis has been traditionally used in the supportive treatment of inflammatory and neuronal diseases in Korea and China. Although several reports have shown the anti-inflammatory effects of Buddleja officinalis, the anti-neuroinflammatory effect has remained unclear. In this study, we aimed to investigate the inhibitory effects of flower buds of B. officinalis Maximowicz water extract (BOWE on LPS-induced inflammatory processes in BV-2 microglial cells. BOWE dose-dependently inhibited the production of nitric oxide as well as iNOS mRNA expression. Moreover, BOWE prevented IL-1β and IL-6 mRNA expression. However, BOWE had no effect on LPS-induced COX-2 or TNF-a mRNA expression. The extract also had no effect on LPS-stimulated p38 MAPK, JNK, and c-Jun phosphorylation, whereas ERK1/2 phosphorylation was strongly inhibited by BOWE. BOWE also inhibited the LPS-induced degradation of IkB-α, and LPS-induced phosphorylation of p65 NF-kB protein. These data indicate that BOWE inhibited the nitric oxide production and pro-inflammatory gene expression in BV-2 microglial cells, possibly through a negative regulation of the NF-kB and ERK1/2 pathways. Further identification of the direct target molecule(s of BOWE is required to support its use as an anti-neuroinflammatory agent against the neurodegenerative disorders.

Delineating neurotrophin-3 dependent signaling pathways underlying sympathetic axon growth along intermediate targets.

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Keeler, Austin B; Suo, Dong; Park, Juyeon; Deppmann, Christopher D

2017-07-01

Postganglionic sympathetic neurons detect vascular derived neurotrophin 3 (NT3) via the axonally expressed receptor tyrosine kinase, TrkA, to promote chemo-attraction along intermediate targets. Once axons arrive to their final target, a structurally related neurotrophic factor, nerve growth factor (NGF), also acts through TrkA to promote final target innervation. Does TrkA signal differently at these different locales? We previously found that Coronin-1 is upregulated in sympathetic neurons upon exposure to NGF, thereby endowing the NGF-TrkA complex with new signaling capabilities (i.e. calcium signaling), which dampens axon growth and branching. Based on the notion that axons do not express functional levels of Coronin-1 prior to final target innervation, we developed an in vitro model for axon growth and branching along intermediate targets using Coro1a -/- neurons grown in NT3. We found that, similar to NGF-TrkA, NT3-TrkA is capable of inducing MAPK and PI3K in the presence or absence of Coronin-1. However, unlike NGF, NT3 does not induce calcium release from intracellular stores. Using a combination of pharmacology, knockout neurons and in vitro functional assays, we suggest that the NT3-TrkA complex uses Ras/MAPK and/or PI3K-AKT signaling to induce axon growth and inhibit axon branching along intermediate targets. However, in the presence of Coronin-1, these signaling pathways lose their ability to impact NT3 dependent axon growth or branching. This is consistent with a role for Coronin-1 as a molecular switch for axon behavior and suggests that Coronin-1 suppresses NT3 dependent axon behavior. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon.

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Ma, Marek

2013-12-01

Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed. © 2013.

Vaccinium bracteatum Thunb. Exerts Anti-Inflammatory Activity by Inhibiting NF-κB Activation in BV-2 Microglial Cells.

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Kwon, Seung-Hwan; Ma, Shi-Xun; Ko, Yong-Hyun; Seo, Jee-Yeon; Lee, Bo-Ram; Lee, Taek Hwan; Kim, Sun Yeou; Lee, Seok-Yong; Jang, Choon-Gon

2016-09-01

This study was designed to evaluate the pharmacological effects of Vaccinium bracteatum Thunb. methanol extract (VBME) on microglial activation and to identify the underlying mechanisms of action of these effects. The anti-inflammatory properties of VBME were studied using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. We measured the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E₂ (PGE₂), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) as inflammatory parameters. We also examined the effect of VBME on intracellular reactive oxygen species (ROS) production and the activity of nuclear factor-kappa B p65 (NF-κB p65). VBME significantly inhibited LPS-induced production of NO and PGE2 and LPS-mediated upregulation of iNOS and COX-2 expression in a dose-dependent manner; importantly, VBME was not cytotoxic. VBME also significantly reduced the generation of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. In addition, VBME significantly dampened intracellular ROS production and suppressed NF-κB p65 translocation by blocking IκB-α phosphorylation and degradation in LPS-stimulated BV2 cells. Our findings indicate that VBME inhibits the production of inflammatory mediators in BV-2 microglial cells by suppressing NF-κB signaling. Thus, VBME may be useful in the treatment of neurodegenerative diseases due to its ability to inhibit inflammatory mediator production in activated BV-2 microglial cells.

The non-psychoactive plant cannabinoid, cannabidiol affects cholesterol metabolism-related genes in microglial cells.

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Rimmerman, Neta; Juknat, Ana; Kozela, Ewa; Levy, Rivka; Bradshaw, Heather B; Vogel, Zvi

2011-08-01

Cannabidiol (CBD) is a non-psychoactive plant cannabinoid that is clinically used in a 1:1 mixture with the psychoactive cannabinoid Δ(9)-tetrahydrocannabinol (THC) for the treatment of neuropathic pain and spasticity in multiple sclerosis. Our group previously reported that CBD exerts anti-inflammatory effects on microglial cells. In addition, we found that CBD treatment increases the accumulation of the endocannabinoid N-arachidonoyl ethanolamine (AEA), thus enhancing endocannabinoid signaling. Here we proceeded to investigate the effects of CBD on the modulation of lipid-related genes in microglial cells. Cell viability was tested using FACS analysis, AEA levels were measured using LC/MS/MS, gene array analysis was validated with real-time qPCR, and cytokine release was measured using ELISA. We report that CBD significantly upregulated the mRNAs of the enzymes sterol-O-acyl transferase (Soat2), which synthesizes cholesteryl esters, and of sterol 27-hydroxylase (Cyp27a1). In addition, CBD increased the mRNA of the lipid droplet-associated protein, perilipin2 (Plin2). Moreover, we found that pretreatment of the cells with the cholesterol chelating agent, methyl-β-cyclodextrin (MBCD), reversed the CBD-induced increase in Soat2 mRNA but not in Plin2 mRNA. Incubation with AEA increased the level of Plin2, but not of Soat2 mRNA. Furthermore, MBCD treatment did not affect the reduction by CBD of the LPS-induced release of the proinflammatory cytokine IL-1β. CBD treatment modulates cholesterol homeostasis in microglial cells, and pretreatment with MBCD reverses this effect without interfering with CBD's anti-inflammatory effects. The effects of the CBD-induced increase in AEA accumulation on lipid-gene expression are discussed.

Schwann cell transplantation improves reticulospinal axon growth and forelimb strength after severe cervical spinal cord contusion.

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Schaal, S M; Kitay, B M; Cho, K S; Lo, T P; Barakat, D J; Marcillo, A E; Sanchez, A R; Andrade, C M; Pearse, D D

2007-01-01

Schwann cell (SC) implantation alone has been shown to promote the growth of propriospinal and sensory axons, but not long-tract descending axons, after thoracic spinal cord injury (SCI). In the current study, we examined if an axotomy close to the cell body of origin (so as to enhance the intrinsic growth response) could permit supraspinal axons to grow onto SC grafts. Adult female Fischer rats received a severe (C5) cervical contusion (1.1 mm displacement, 3 KDyn). At 1 week postinjury, 2 million SCs ex vivo transduced with lentiviral vector encoding enhanced green fluorescent protein (EGFP) were implanted within media into the injury epicenter; injury-only animals served as controls. Animals were tested weekly using the BBB score for 7 weeks postimplantation and received at end point tests for upper body strength: self-supported forelimb hanging, forearm grip force, and the incline plane. Following behavioral assessment, animals were anterogradely traced bilaterally from the reticular formation using BDA-Texas Red. Stereological quantification revealed a twofold increase in the numbers of preserved NeuN+ neurons rostral and caudal to the injury/graft site in SC implanted animals, corroborating previous reports of their neuroprotective efficacy. Examination of labeled reticulospinal axon growth revealed that while rarely an axon was present within the lesion site of injury-only controls, numerous reticulospinal axons had penetrated the SC implant/lesion milieu. This has not been observed following implantation of SCs alone into the injured thoracic spinal cord. Significant behavioral improvements over injury-only controls in upper limb strength, including an enhanced grip strength (a 296% increase) and an increased self-supported forelimb hanging, accompanied SC-mediated neuroprotection and reticulospinal axon growth. The current study further supports the neuroprotective efficacy of SC implants after SCI and demonstrates that SCs alone are capable of supporting

Cromolyn Reduces Levels of the Alzheimer's Disease-Associated Amyloid β-Protein by Promoting Microglial Phagocytosis.

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Zhang, Can; Griciuc, Ana; Hudry, Eloise; Wan, Yu; Quinti, Luisa; Ward, Joseph; Forte, Angela M; Shen, Xunuo; Ran, ChongZhao; Elmaleh, David R; Tanzi, Rudolph E

2018-01-18

Amyloid-beta protein (Aβ) deposition is a pathological hallmark of Alzheimer's disease (AD). Aβ deposition triggers both pro-neuroinflammatory microglial activation and neurofibrillary tangle formation. Cromolyn sodium is an asthma therapeutic agent previously shown to reduce Aβ levels in transgenic AD mouse brains after one-week of treatment. Here, we further explored these effects as well as the mechanism of action of cromolyn, alone, and in combination with ibuprofen in APP Swedish -expressing Tg2576 mice. Mice were treated for 3 months starting at 5 months of age, when the earliest stages of β-amyloid deposition begin. Cromolyn, alone, or in combination with ibuprofen, almost completely abolished longer insoluble Aβ species, i.e. Aβ40 and Aβ42, but increased insoluble Aβ38 levels. In addition to its anti-aggregation effects on Aβ, cromolyn, alone, or plus ibuprofen, but not ibuprofen alone, increased microglial recruitment to, and phagocytosis of β-amyloid deposits in AD mice. Cromolyn also promoted Aβ42 uptake in microglial cell-based assays. Collectively, our data reveal robust effects of cromolyn, alone, or in combination with ibuprofen, in reducing aggregation-prone Aβ levels and inducing a neuroprotective microglial activation state favoring Aβ phagocytosis versus a pro-neuroinflammatory state. These findings support the use of cromolyn, alone, or with ibuprofen, as a potential AD therapeutic.

Loss of Fractalkine Signaling Exacerbates Axon Transport Dysfunction in a Chronic Model of Glaucoma.

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Breen, Kevin T; Anderson, Sarah R; Steele, Michael R; Calkins, David J; Bosco, Alejandra; Vetter, Monica L

2016-01-01

Neurodegeneration in glaucoma results in decline and loss of retinal ganglion cells (RGCs), and is associated with activation of myeloid cells such as microglia and macrophages. The chemokine fractalkine (FKN or Cx3cl1) mediates communication from neurons to myeloid cells. Signaling through its receptor Cx3cr1 has been implicated in multiple neurodegenerative diseases, but the effects on neuronal pathology are variable. Since it is unknown how FKN-mediated crosstalk influences RGC degeneration in glaucoma, we assessed this in a chronic mouse model, DBA/2J. We analyzed a DBA/2J substrain deficient in Cx3cr1, and compared compartmentalized RGC degeneration and myeloid cell responses to those in standard DBA/2J mice. We found that loss of FKN signaling exacerbates axon transport dysfunction, an early event in neurodegeneration, with a significant increase in RGCs with somal accumulation of the axonal protein phosphorylated neurofilament, and reduced retinal expression of genes involved in axon transport, Kif1b, and Atp8a2. There was no change in the loss of Brn3-positive RGCs, and no difference in the extent of damage to the proximal optic nerve, suggesting that the loss of fractalkine signaling primarily affects axon transport. Since Cx3cr1 is specifically expressed in myeloid cells, we assessed changes in retinal microglial number and activation, changes in gene expression, and the extent of macrophage infiltration. We found that loss of fractalkine signaling led to innate immune changes within the retina, including increased infiltration of peripheral macrophages and upregulated nitric oxide synthase-2 (Nos-2) expression in myeloid cells, which contributes to the production of NO and can promote axon transport deficits. In contrast, resident retinal microglia appeared unchanged either in number, morphology, or expression of the myeloid activation marker ionized calcium binding adaptor molecule 1 (Iba1). There was also no significant increase in the proinflammatory

Alginate-Derived Oligosaccharide Inhibits Neuroinflammation and Promotes Microglial Phagocytosis of β-Amyloid

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Rui Zhou

2015-09-01

Full Text Available Alginate from marine brown algae has been widely applied in biotechnology. In this work, the effects of alginate-derived oligosaccharide (AdO on lipopolysaccharide (LPS/β-amyloid (Aβ-induced neuroinflammation and microglial phagocytosis of Aβ were studied. We found that pretreatment of BV2 microglia with AdO prior to LPS/Aβ stimulation led to a significant inhibition of production of nitric oxide (NO and prostaglandin E2 (PGE2, expression of inducible nitric oxide synthase (iNOS and cyclooxygenase-2 (COX-2 and secretion of proinflammatory cytokines. We further demonstrated that AdO remarkably attenuated the LPS-activated overexpression of toll-like receptor 4 (TLR4 and nuclear factor (NF-κB in BV2 cells. In addition to the impressive inhibitory effect on neuroinflammation, we also found that AdO promoted the phagocytosis of Aβ through its interaction with TLR4 in microglia. Our results suggested that AdO exerted the inhibitory effect on neuroinflammation and the promotion effect on microglial phagocytosis, indicating its potential as a nutraceutical or therapeutic agent for neurodegenerative diseases, particularly Alzheimer’s disease (AD.

Plasminogen activator inhibitor type 1 regulates microglial motility and phagocytic activity

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Jeon Hyejin

2012-06-01

Full Text Available Abstract Background Plasminogen activator inhibitor type 1 (PAI-1 is the primary inhibitor of urokinase type plasminogen activators (uPA and tissue type plasminogen activators (tPA, which mediate fibrinolysis. PAI-1 is also involved in the innate immunity by regulating cell migration and phagocytosis. However, little is known about the role of PAI-1 in the central nervous system. Methods In this study, we identified PAI-1 in the culture medium of mouse mixed glial cells by liquid chromatography and tandem mass spectrometry. Secretion of PAI-1 from glial cultures was detected by ELISA and western blotting analysis. Cell migration was evaluated by in vitro scratch-wound healing assay or Boyden chamber assay and an in vivo stab wound injury model. Phagocytic activity was measured by uptake of zymosan particles. Results The levels of PAI-1 mRNA and protein expression were increased by lipopolysaccharide and interferon-γ stimulation in both microglia and astrocytes. PAI-1 promoted the migration of microglial cells in culture via the low-density lipoprotein receptor-related protein (LRP 1/Janus kinase (JAK/signal transducer and activator of transcription (STAT1 axis. PAI-1 also increased microglial migration in vivo when injected into mouse brain. PAI-1-mediated microglial migration was independent of protease inhibition, because an R346A mutant of PAI-1 with impaired PA inhibitory activity also promoted microglial migration. Moreover, PAI-1 was able to modulate microglial phagocytic activity. PAI-1 inhibited microglial engulfment of zymosan particles in a vitronectin- and Toll-like receptor 2/6-dependent manner. Conclusion Our results indicate that glia-derived PAI-1 may regulate microglial migration and phagocytosis in an autocrine or paracrine manner. This may have important implications in the regulation of brain microglial activities in health and disease.

A new synthetic chalcone derivative, 2-hydroxy-3',5,5'-trimethoxychalcone (DK-139), suppresses the Toll-like receptor 4-mediated inflammatory response through inhibition of the Akt/NF-κB pathway in BV2 microglial cells.

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Lee, Young Han; Jeon, Seung-Hyun; Kim, Se Hyun; Kim, Changyoun; Lee, Seung-Jae; Koh, Dongsoo; Lim, Yoongho; Ha, Kyooseob; Shin, Soon Young

2012-06-30

Microglial cells are the resident innate immune cells that sense pathogens and tissue injury in the central nervous system (CNS). Microglial activation is critical for neuroinflammatory responses. The synthetic compound 2-hydroxy-3',5,5'-trimethoxychalcone (DK-139) is a novel chalcone-derived compound. In this study, we investigated the effects of DK-139 on Toll-like receptor 4 (TLR4)-mediated inflammatory responses in BV2 microglial cells. DK-139 inhibited lipopolysaccharide (LPS)-induced TLR4 activity, as determined using a cell-based assay. DK-139 blocked LPS-induced phosphorylation of IκB and p65/RelA NF-κB, resulting in inhibition of the nuclear translocation and trans-acting activity of NF-κB in BV2 microglial cells. We also found that DK-139 reduced the expression of NF-κB target genes, such as those for COX-2, iNOS, and IL-1β, in LPS-stimulated BV2 microglial cells. Interestingly, DK-139 blocked LPS-induced Akt phosphorylation. Inhibition of Akt abrogated LPS-induced phosphorylation of p65/RelA, while overexpression of dominant- active p110CAAX enhanced p65/RelA phosphorylation as well as iNOS and COX2 expression. These results suggest that DK-139 exerts an anti-inflammatory effect on microglial cells by inhibiting the Akt/IκB kinase (IKK)/NF-κB signaling pathway.

Involvement of both sodium influx and potassium efflux in ciguatoxin-induced nodal swelling of frog myelinated axons.

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Mattei, César; Molgó, Jordi; Benoit, Evelyne

2014-10-01

Ciguatoxins, mainly produced by benthic dinoflagellate Gambierdiscus species, are responsible for a complex human poisoning known as ciguatera. Previous pharmacological studies revealed that these toxins activate voltage-gated Na+ channels. In frog nodes of Ranvier, ciguatoxins induce spontaneous and repetitive action potentials (APs) and increase axonal volume that may explain alterations of nerve functioning in intoxicated humans. The present study aimed determining the ionic mechanisms involved in Pacific ciguatoxin-1B (P-CTX-1B)-induced membrane hyperexcitability and subsequent volume increase in frog nodes of Ranvier, using electrophysiology and confocal microscopy. The results reveal that P-CTX-1B action is not dependent on external Cl- ions since it was not affected by substituting Cl- by methylsulfate ions. In contrast, substitution of external Na+ by Li+ ions suppressed spontaneous APs and prevented nodal swelling. This suggests that P-CTX-1B-modified Na+ channels are not selective to Li+ ions and/or are blocked by these ions, and that Na+ influx through Na+ channels opened during spontaneous APs is required for axonal swelling. The fact that the K+ channel blocker tetraethylammonium modified, but did not suppress, spontaneous APs and greatly reduced nodal swelling induced by P-CTX-1B indicates that K+ efflux might also be involved. This is supported by the fact that P-CTX-1B, when tested in the presence of both tetraethylammonium and the K+ ionophore valinomycin, produced the characteristic nodal swelling. It is concluded that, during the action of P-CTX-1B, water movements responsible for axonal swelling depend on both Na+ influx and K+ efflux. These results pave the way for further studies regarding ciguatera treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamics of target recognition by interstitial axon branching along developing cortical axons.

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Bastmeyer, M; O'Leary, D D

1996-02-15

Corticospinal axons innervate their midbrain, hindbrain, and spinal targets by extending collateral branches interstitially along their length. To establish that the axon shaft rather than the axonal growth cone is responsible for target recognition in this system, and to characterize the dynamics of interstitial branch formation, we have studied this process in an in vivo-like setting using slice cultures from neonatal mice containing the entire pathway of corticospinal axons. Corticospinal axons labeled with the dye 1,1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (or Dil) were imaged using time-lapse video microscopy of their pathway overlying the basilar pons, their major hindbrain target. The axon shaft millimeters behind the growth cone exhibits several dynamic behaviors, including the de novo formation of varicosities and filopodia-like extensions, and a behavior that we term "pulsation," which is characterized by a variable thickening and thining of short segments of the axon. An individual axon can have multiple sites of branching activity, with many of the branches being transient. These dynamic behaviors occur along the portion of the axon shaft overlying the basilar pons, but not just caudal to it. Once the collaterals extend into the pontine neuropil, they branch further in the neuropil, while the parent axon becomes quiescent. Thus, the branching activity is spatially restricted to specific portions of the axon, as well as temporally restricted to a relatively brief time window. These findings provide definitive evidence that collateral branches form de novo along corticospinal axons and establish that the process of target recognition in this system is a property of the axon shaft rather than the leading growth cone.

Impact of cavitation on lesion formation induced by high intensity focused ultrasound

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Fan Pengfei; Jie Yu; Yang Xin; Tu Juan; Guo Xiasheng; Zhang Dong; Huang Pintong

2017-01-01

High intensity focused ultrasound (HIFU) has shown a great promise in noninvasive cancer therapy. The impact of acoustic cavitation on the lesion formation induced by HIFU is investigated both experimentally and theoretically in transparent protein-containing gel and ex vivo liver tissue samples. A numerical model that accounts for nonlinear acoustic propagation and heat transfer is used to simulate the lesion formation induced by the thermal effect. The results showed that lesions could be induced in the samples exposed to HIFU with various acoustic pressures and pulse lengths. The measured areas of lesions formed in the lateral direction were comparable to the simulated results, while much larger discrepancy was observed between the experimental and simulated data for the areas of longitudinal lesion cross-section. Meanwhile, a series of stripe-wiped-off B-mode pictures were obtained by using a special imaging processing method so that HIFU-induced cavitation bubble activities could be monitored in real-time and quantitatively analyzed as the functions of acoustic pressure and pulse length. The results indicated that, unlike the lateral area of HIFU-induced lesion that was less affected by the cavitation activity, the longitudinal cross-section of HIFU-induced lesion was significantly influenced by the generation of cavitation bubbles through the temperature elevation resulting from HIFU exposures. Therefore, considering the clinical safety in HIFU treatments, more attention should be paid on the lesion formation in the longitudinal direction to avoid uncontrollable variation resulting from HIFU-induced cavitation activity. (paper)

Time-dependent retinal ganglion cell loss, microglial activation and blood-retina-barrier tightness in an acute model of ocular hypertension.

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Trost, A; Motloch, K; Bruckner, D; Schroedl, F; Bogner, B; Kaser-Eichberger, A; Runge, C; Strohmaier, C; Klein, B; Aigner, L; Reitsamer, H A

2015-07-01

Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, and is the second leading cause of blindness worldwide. Elevated intraocular pressure is a well known risk factor for the development of glaucomatous optic neuropathy and pharmacological or surgical lowering of intraocular pressure represents a standard procedure in glaucoma treatment. However, the treatment options are limited and although lowering of intraocular pressure impedes disease progression, glaucoma cannot be cured by the currently available therapy concepts. In an acute short-term ocular hypertension model in rat, we characterize RGC loss, but also microglial cell activation and vascular alterations of the retina at certain time points. The combination of these three parameters might facilitate a better evaluation of the disease progression, and could further serve as a new model to test novel treatment strategies at certain time points. Acute ocular hypertension (OHT) was induced by the injection of magnetic microbeads into the rat anterior chamber angle (n = 22) with magnetic position control, leading to constant elevation of IOP. At certain time points post injection (4d, 7d, 10d, 14d and 21d), RGC loss, microglial activation, and microvascular pericyte (PC) coverage was analyzed using immunohistochemistry with corresponding specific markers (Brn3a, Iba1, NG2). Additionally, the tightness of the retinal vasculature was determined via injections of Texas Red labeled dextran (10 kDa) and subsequently analyzed for vascular leakage. For documentation, confocal laser-scanning microscopy was used, followed by cell counts, capillary length measurements and morphological and statistical analysis. The injection of magnetic microbeads led to a progressive loss of RGCs at the five time points investigated (20.07%, 29.52%, 41.80%, 61.40% and 76.57%). Microglial cells increased in number and displayed an activated morphology

Inhibition of CD200R1 expression by C/EBP beta in reactive microglial cells

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Dentesano Guido

2012-07-01

Full Text Available Abstract Background In physiological conditions, it is postulated that neurons control microglial reactivity through a series of inhibitory mechanisms, involving either cell contact-dependent, soluble-factor-dependent or neurotransmitter-associated pathways. In the current study, we focus on CD200R1, a microglial receptor involved in one of these cell contact-dependent mechanisms. CD200R1 activation by its ligand, CD200 (mainly expressed by neurons in the central nervous system,is postulated to inhibit the pro-inflammatory phenotype of microglial cells, while alterations in CD200-CD200R1 signalling potentiate this phenotype. Little is known about the regulation of CD200R1 expression in microglia or possible alterations in the presence of pro-inflammatory stimuli. Methods Murine primary microglial cultures, mixed glial cultures from wild-type and CCAAT/enhancer binding protein β (C/EBPβ-deficient mice, and the BV2 murine cell line overexpressing C/EBPβ were used to study the involvement of C/EBPβ transcription factor in the regulation of CD200R1 expression in response to a proinflammatory stimulus (lipopolysaccharide (LPS. Binding of C/EBPβ to the CD200R1 promoter was determined by quantitative chromatin immunoprecipitation (qChIP. The involvement of histone deacetylase 1 in the control of CD200R1 expression by C/EBPβ was also determined by co-immunoprecipitation and qChIP. Results LPS treatment induced a decrease in CD200R1 mRNA and protein expression in microglial cells, an effect that was not observed in the absence of C/EBPβ. C/EBPβ overexpression in BV2 cells resulted in a decrease in basal CD200R1 mRNA and protein expression. In addition, C/EBPβ binding to the CD200R1 promoter was observed in LPS-treated but not in control glial cells, and also in control BV2 cells overexpressing C/EBPβ. Finally, we observed that histone deacetylase 1 co-immunoprecipitated with C/EBPβ and showed binding to a C/EBPβ consensus sequence of the CD

A Combinatorial Approach to Induce Sensory Axon Regeneration into the Dorsal Root Avulsed Spinal Cord

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Hoeber, Jan; Konig, Niclas; Trolle, Carl

2017-01-01

Spinal root injuries result in newly formed glial scar formation, which prevents regeneration of sensory axons causing permanent sensory loss. Previous studies showed that delivery of trophic factors or implantation of human neural progenitor cells supports sensory axon regeneration and partly......MIM), supported sensory axon regeneration. However, when hscNSPC and MesoMIM were combined, sensory axon regeneration failed. Morphological and tracing analysis showed that sensory axons grow through the newly established glial scar along “bridges” formed by migrating stem cells. Coimplantation of Meso...... their level of differentiation. Our data show that (1) the ability of stem cells to migrate into the spinal cord and organize cellular “bridges” in the newly formed interface is crucial for successful sensory axon regeneration, (2) trophic factor mimetics delivered by mesoporous silica may be a convenient...

Axonal GABAA receptors.

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Trigo, Federico F; Marty, Alain; Stell, Brandon M

2008-09-01

Type A GABA receptors (GABA(A)Rs) are well established as the main inhibitory receptors in the mature mammalian forebrain. In recent years, evidence has accumulated showing that GABA(A)Rs are prevalent not only in the somatodendritic compartment of CNS neurons, but also in their axonal compartment. Evidence for axonal GABA(A)Rs includes new immunohistochemical and immunogold data: direct recording from single axonal terminals; and effects of local applications of GABA(A)R modulators on action potential generation, on axonal calcium signalling, and on neurotransmitter release. Strikingly, whereas presynaptic GABA(A)Rs have long been considered inhibitory, the new studies in the mammalian brain mostly indicate an excitatory action. Depending on the neuron that is under study, axonal GABA(A)Rs can be activated by ambient GABA, by GABA spillover, or by an autocrine action, to increase either action potential firing and/or transmitter release. In certain neurons, the excitatory effects of axonal GABA(A)Rs persist into adulthood. Altogether, axonal GABA(A)Rs appear as potent neuronal modulators of the mammalian CNS.

Cross-talk between KLF4 and STAT3 regulates axon regeneration

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Qin, Song; Zou, Yuhua; Zhang, Chun-Li

2013-10-01

Cytokine-induced activation of signal transducer and activator of transcription 3 (STAT3) promotes the regrowth of damaged axons in the adult central nervous system (CNS). Here we show that KLF4 physically interacts with STAT3 upon cytokine-induced phosphorylation of tyrosine 705 (Y705) on STAT3. This interaction suppresses STAT3-dependent gene expression by blocking its DNA-binding activity. The deletion of KLF4 in vivo induces axon regeneration of adult retinal ganglion cells (RGCs) via Janus kinase (JAK)-STAT3 signalling. This regeneration can be greatly enhanced by exogenous cytokine treatment, or removal of an endogenous JAK-STAT3 pathway inhibitor called suppressor of cytokine signalling 3 (SOCS3). These findings reveal an unexpected cross-talk between KLF4 and activated STAT3 in the regulation of axon regeneration that might have therapeutic implications in promoting repair of injured adult CNS.

Clearing the corpses: regulatory mechanisms, novel tools, and therapeutic potential of harnessing microglial phagocytosis in the diseased brain

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Irune Diaz-Aparicio

2016-01-01

Full Text Available Apoptosis is a widespread phenomenon that occurs in the brain in both physiological and pathological conditions. Dead cells must be quickly removed to avoid the further toxic effects they exert in the parenchyma, a process executed by microglia, the brain professional phagocytes. Although phagocytosis is critical to maintain tissue homeostasis, it has long been either overlooked or indirectly assessed based on microglial morphology, expression of classical activation markers, or engulfment of artificial phagocytic targets in vitro. Nevertheless, these indirect methods present several limitations and, thus, direct observation and quantification of microglial phagocytosis is still necessary to fully grasp its relevance in the diseased brain. To overcome these caveats and obtain a comprehensive, quantitative picture of microglial phagocytosis we have developed a novel set of parameters. These parameters have allowed us to identify the different strategies utilized by microglia to cope with apoptotic challenges induced by excitotoxicity or inflammation. In contrast, we discovered that in mouse and human epilepsy microglia failed to find and engulf apoptotic cells, resulting in accumulation of debris and inflammation. Herein, we advocate that the efficiency of microglial phagocytosis should be routinely tested in neurodegenerative and neurological disorders, in order to determine the extent to which it contributes to apoptosis and inflammation found in these conditions. Finally, our findings point towards enhancing microglial phagocytosis as a novel therapeutic strategy to control tissue damage and inflammation, and accelerate recovery in brain diseases.

Axonal degeneration stimulates the formation of NG2+ cells and oligodendrocytes in the mouse

DEFF Research Database (Denmark)

Nielsen, Helle Hvilsted; Ladeby, Rune; Drøjdahl, Nina

2006-01-01

the response of the NG2+ cells to the different components of demyelinating pathology, we investigated the response of adult NG2+ cells to axonal degeneration in the absence of primary myelin or oligodendrocyte pathology. Axonal degeneration was induced in the hippocampal dentate gyrus of adult mice...... by transection of the entorhino-dentate perforant path projection. The acutely induced degeneration of axons and terminals resulted in a prompt response of NG2+ cells, consisting of morphological transformation, cellular proliferation, and upregulation of NG2 expression days 2-3 after surgery. This was followed...

Lipoxin A4 inhibits microglial activation and reduces neuroinflammation and neuropathic pain after spinal cord hemisection.

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Martini, Alessandra Cadete; Berta, Temugin; Forner, Stefânia; Chen, Gang; Bento, Allisson Freire; Ji, Ru-Rong; Rae, Giles Alexander

2016-04-08

Spinal cord injury (SCI) is a severe neurological disorder with many disabling consequences, including persistent neuropathic pain, which develops in about 40 % of SCI patients and is induced and sustained by excessive and uncontrolled spinal neuroinflammation. Here, we have evaluated the effects of lipoxin A4 (LXA4), a member of a unique class of endogenous lipid mediators with both anti-inflammatory and analgesic properties, on spinal neuroinflammation and chronic pain in an experimental model of SCI. Spinal hemisection at T10 was carried out in adult male CD1 mice and Wistar rats. To test if LXA4 can reduce neuroinflammation and neuropathic pain, each animal received two intrathecal injections of LXA4 (300 pmol) or vehicle at 4 and 24 h after SCI. Sensitivity to mechanical stimulation of the hind paws was evaluated using von Frey monofilaments, and neuroinflammation was tested by measuring the mRNA and/or protein expression levels of glial markers and cytokines in the spinal cord samples after SCI. Also, microglia cultures prepared from murine cortical tissue were used to assess the direct effects of LXA4 on microglial activation and release of pro-inflammatory TNF-α. LXA4 treatment caused significant reductions in the intensity of mechanical pain hypersensitivity and spinal expression levels of microglial markers and pro-inflammatory cytokines induced by SCI, when compared to rodents receiving control vehicle injections. Notably, the increased expressions of the microglial marker IBA-1 and of the pro-inflammatory cytokine TNF-α were the most affected by the LXA4 treatment. Furthermore, cortical microglial cultures expressed ALX/FPR2 receptors for LXA4 and displayed potentially anti-inflammatory responses upon challenge with LXA4. Collectively, our results suggest that LXA4 can effectively modulate microglial activation and TNF-α release through ALX/FPR2 receptors, ultimately reducing neuropathic pain in rodents after spinal cord hemisection. The dual anti

N-docosahexaenoylethanolamine regulates Hedgehog signaling and promotes growth of cortical axons

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Giorgi Kharebava

2015-12-01

Full Text Available Axonogenesis, a process for the establishment of neuron connectivity, is central to brain function. The role of metabolites derived from docosahexaenoic acid (DHA, 22:6n-3 that is specifically enriched in the brain, has not been addressed in axon development. In this study, we tested if synaptamide (N-docosahexaenoylethanolamine, an endogenous metabolite of DHA, affects axon growth in cultured cortical neurons. We found that synaptamide increased the average axon length, inhibited GLI family zinc finger 1 (GLI1 transcription and sonic hedgehog (Shh target gene expression while inducing cAMP elevation. Similar effects were produced by cyclopamine, a regulator of the Shh pathway. Conversely, Shh antagonized elevation of cAMP and blocked synaptamide-mediated increase in axon length. Activation of Shh pathway by a smoothened (SMO agonist (SAG or overexpression of SMO did not inhibit axon growth mediated by synaptamide or cyclopamine. Instead, adenylate cyclase inhibitor SQ22536 abolished synaptamide-mediated axon growth indicating requirement of cAMP elevation for this process. Our findings establish that synaptamide promotes axon growth while Shh antagonizes synaptamide-mediated cAMP elevation and axon growth by a SMO-independent, non-canonical pathway.

Deciphering resting microglial morphology and process motility from a synaptic prospect

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Ines eHristovska

2016-01-01

Full Text Available Microglia, the resident immune cells of the central nervous system (CNS, were traditionally believed to be set into action only in case of injury or disease. Accordingly, microglia were assumed to be inactive or resting in the healthy brain. However, recent studies revealed that microglia carry out active tissue sampling in the intact brain by extending and retracting their ramified processes while periodically contacting synapses. Microglial morphology and motility as well as the frequency and duration of physical contacts with synaptic elements were found to be modulated by neuronal activity, sensory experience and neurotransmission; however findings have not been straightforward. Microglial cells are the most morphologically plastic element of the CNS. This unique feature confers them the possibility to locally sense activity, and to respond adequately by establishing synaptic contacts to regulate synaptic inputs by the secretion of signaling molecules. Indeed, microglial cells can hold new roles as critical players in maintaining brain homeostasis and regulating synaptic number, maturation and plasticity. For this reason, a better characterization of microglial cells and cues mediating neuron-to-microglia communication under physiological conditions may help advance our understanding of the microglial behavior and its regulation in the healthy brain. This review highlights recent findings on the instructive role of neuronal activity on microglial motility and microglia-synapse interactions, focusing on the main transmitters involved in this communication and including newly described communication at the tripartite synapse.

stimulated BV2 Microglial

African Journals Online (AJOL)

2012-03-26

Mar 26, 2012 ... 2), in LPS-stimulated BV2 microglial cells. The level of NO production was analyzed using Griess reaction. The release of PGE2 was determined using sandwich enzyme-linked immunosorbent assay. The DNA-binding activity of nuclear factor-κB (NF-κB) was measured by electrophoretic mobility shift assay ...

Excitability properties of motor axons in adults with cerebral palsy

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Cliff S. Klein

2015-06-01

Full Text Available Cerebral Palsy (CP is a permanent disorder caused by a lesion to the developing brain that significantly impairs motor function. The neurophysiological mechanisms underlying motor impairment are not well understood. Specifically, few have addressed whether motoneuron or peripheral axon properties are altered in CP, even though disruption of descending inputs to the spinal cord may cause them to change. In the present study, we have compared nerve excitability properties in seven adults with CP and fourteen healthy controls using threshold tracking techniques by stimulating the median nerve at the wrist and recording the compound muscle action potential (CMAP over the abductor pollicis brevis. The excitability properties in the CP subjects were found to be abnormal. Early and late depolarizing and hyperpolarizing threshold electrotonus was significantly larger (i.e., fanning out, and resting current-threshold (I/V slope was smaller, in CP compared to control. In addition resting threshold and rheobase tended to be larger in CP. According to a modeling analysis of the data, an increase in leakage current under or through the myelin sheath, i.e., the Barrett-Barrett conductance (GBB, combined with a slight hyperpolarization of the resting membrane potential, best explained the group differences in excitability properties. There was a trend for those with greater impairment in gross motor function to have more abnormal axon properties. The findings indicate plasticity of motor axon properties far removed from the site of the lesion. We suspect that this plasticity is caused by disruption of descending inputs to the motoneurons at an early age around the time of their injury.

NMNAT1 inhibits axon degeneration via blockade of SARM1-mediated NAD+ depletion

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Sasaki, Yo; Nakagawa, Takashi; Mao, Xianrong; DiAntonio, Aaron; Milbrandt, Jeffrey

2016-01-01

Overexpression of the NAD+ biosynthetic enzyme NMNAT1 leads to preservation of injured axons. While increased NAD+ or decreased NMN levels are thought to be critical to this process, the mechanism(s) of this axon protection remain obscure. Using steady-state and flux analysis of NAD+ metabolites in healthy and injured mouse dorsal root ganglion axons, we find that rather than altering NAD+ synthesis, NMNAT1 instead blocks the injury-induced, SARM1-dependent NAD+ consumption that is central to axon degeneration. DOI: http://dx.doi.org/10.7554/eLife.19749.001 PMID:27735788

Ascending Midbrain Dopaminergic Axons Require Descending GAD65 Axon Fascicles for Normal Pathfinding

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Claudia Marcela Garcia-Peña

2014-06-01

Full Text Available The Nigrostriatal pathway (NSP is formed by dopaminergic axons that project from the ventral midbrain to the dorsolateral striatum as part of the medial forebrain bundle. Previous studies have implicated chemotropic proteins in the formation of the NSP during development but little is known of the role of substrate-anchored signals in this process. We observed in mouse and rat embryos that midbrain dopaminergic axons ascend in close apposition to descending GAD65-positive axon bundles throughout their trajectory to the striatum. To test whether such interaction is important for dopaminergic axon pathfinding, we analyzed transgenic mouse embryos in which the GAD65 axon bundle was reduced by the conditional expression of the diphtheria toxin. In these embryos we observed dopaminergic misprojection into the hypothalamic region and abnormal projection in the striatum. In addition, analysis of Robo1/2 and Slit1/2 knockout embryos revealed that the previously described dopaminergic misprojection in these embryos is accompanied by severe alterations in the GAD65 axon scaffold. Additional studies with cultured dopaminergic neurons and whole embryos suggest that NCAM and Robo proteins are involved in the interaction of GAD65 and dopaminergic axons. These results indicate that the fasciculation between descending GAD65 axon bundles and ascending dopaminergic axons is required for the stereotypical NSP formation during brain development and that known guidance cues may determine this projection indirectly by instructing the pathfinding of the axons that are part of the GAD65 axon scaffold.

Intra-axonal Synthesis of SNAP25 Is Required for the Formation of Presynaptic Terminals

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Andreia F.R. Batista

2017-09-01

Full Text Available Localized protein synthesis is a mechanism for developing axons to react acutely and in a spatially restricted manner to extracellular signals. As such, it is important for many aspects of axonal development, but its role in the formation of presynapses remains poorly understood. We found that the induced assembly of presynaptic terminals required local protein synthesis. Newly synthesized proteins were detectable at nascent presynapses within 15 min of inducing synapse formation in isolated axons. The transcript for the t-SNARE protein SNAP25, which is required for the fusion of synaptic vesicles with the plasma membrane, was recruited to presynaptic sites and locally translated. Inhibition of intra-axonal SNAP25 synthesis affected the clustering of SNAP25 and other presynaptic proteins and interfered with the release of synaptic vesicles from presynaptic sites. This study reveals a critical role for the axonal synthesis of SNAP25 in the assembly of presynaptic terminals.

Cocaine promotes oxidative stress and microglial-macrophage activation in rat cerebellum

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Rosa M López-Pedrajas

2015-07-01

Full Text Available Different mechanisms have been suggested for cocaine neurotoxicity, including oxidative stress alterations. Nuclear factor kappa B (NF-κB, considered a sensor of oxidative stress and inflammation, is involved in drug toxicity and addiction. NF-κB is a key mediator for immune responses that induces microglial/macrophage activation under inflammatory processes and neuronal injury/degeneration. Although cerebellum is commonly associated to motor control, muscular tone and balance. Its relation with addiction is getting relevance, being associated to compulsive and perseverative behaviors. Some reports indicate that cerebellar microglial activation induced by cannabis or ethanol, promote cerebellar alterations and these alterations could be associated to addictive-related behaviors. After considering the effects of some drugs on cerebellum, the aim of the present work analyzes pro-inflammatory changes after cocaine exposure. Rats received daily 15 mg/kg cocaine i.p. for 18 days. Reduced and oxidized forms of glutathione (GSH and GSSG, glutathione peroxidase (GPx activity and glutamate were determined in cerebellar homogenates. NF-κB activity, CD68 and GFAP expression were determined.Cerebellar GPx activity and GSH/GSSG ratio are significantly decreased after cocaine exposure. A significant increase of glutamate concentration is also observed. Interestingly, increased NF-κB activity is also accompanied by an increased expression of the lysosomal mononuclear phagocytic marker ED1 without GFAP alterations.Current trends in addiction biology are focusing on the role of cerebellum on addictive behaviors. Cocaine-induced cerebellar changes described herein fit with previosus data showing cerebellar alterations on addict subjects and support the proposed role of cerebelum in addiction.

MRI findings in acute diffuse axonal injured patients

International Nuclear Information System (INIS)

Sato, Hidetaka

2001-01-01

Diffuse axonal injury (DAI) in the acute stage was clinically evaluated using magnetic resonance imaging (MRI), which is considered superior to computed tomography (CT) in detecting parenchymal brain lesions. MRI was disadvantageous, however, to patients suffering from acute severe head injury because of the long time required to construct imaging and unstable patient vital signs. We conducted MRI safely under a high magnetic field (1.5 tesla) in acute DAI by close observation and with nonmagnetic respirator and electrocardiographic monitoring. MRI was conducted in 95 patients diagnosed with DAI classified into mild (14), moderate (17) and severe (64) DAI by criteria established by Gennarelli (1986). In patients with mild or moderate DAI, CT revealed no lesion in the parenchymal area although MRI detected lesions in every case, mainly in cortical white matter or basal ganglia. In patients with severe DAI, CT revealed parenchymal lesions in 14 although MRI detected further lesions in cortical white matter, basal ganglia, corpus callosum and brainstem in every case. These results correspond well to the experimental model Gennarelli's. This study concluded that MRI was useful in assessing acute DAI patients. (author)

Molecular Analysis of Sensory Axon Branching Unraveled a cGMP-Dependent Signaling Cascade.

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Dumoulin, Alexandre; Ter-Avetisyan, Gohar; Schmidt, Hannes; Rathjen, Fritz G

2018-04-24

Axonal branching is a key process in the establishment of circuit connectivity within the nervous system. Molecular-genetic studies have shown that a specific form of axonal branching—the bifurcation of sensory neurons at the transition zone between the peripheral and the central nervous system—is regulated by a cyclic guanosine monophosphate (cGMP)-dependent signaling cascade which is composed of C-type natriuretic peptide (CNP), the receptor guanylyl cyclase Npr2, and cGMP-dependent protein kinase Iα (cGKIα). In the absence of any one of these components, neurons in dorsal root ganglia (DRG) and cranial sensory ganglia no longer bifurcate, and instead turn in either an ascending or a descending direction. In contrast, collateral axonal branch formation which represents a second type of axonal branch formation is not affected by inactivation of CNP, Npr2, or cGKI. Whereas axon bifurcation was lost in mouse mutants deficient for components of CNP-induced cGMP formation; the absence of the cGMP-degrading enzyme phosphodiesterase 2A had no effect on axon bifurcation. Adult mice that lack sensory axon bifurcation due to the conditional inactivation of Npr2-mediated cGMP signaling in DRG neurons demonstrated an altered shape of sensory axon terminal fields in the spinal cord, indicating that elaborate compensatory mechanisms reorganize neuronal circuits in the absence of bifurcation. On a functional level, these mice showed impaired heat sensation and nociception induced by chemical irritants, whereas responses to cold sensation, mechanical stimulation, and motor coordination are normal. These data point to a critical role of axon bifurcation for the processing of acute pain perception.

Molecular Analysis of Sensory Axon Branching Unraveled a cGMP-Dependent Signaling Cascade

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Alexandre Dumoulin

2018-04-01

Full Text Available Axonal branching is a key process in the establishment of circuit connectivity within the nervous system. Molecular-genetic studies have shown that a specific form of axonal branching—the bifurcation of sensory neurons at the transition zone between the peripheral and the central nervous system—is regulated by a cyclic guanosine monophosphate (cGMP-dependent signaling cascade which is composed of C-type natriuretic peptide (CNP, the receptor guanylyl cyclase Npr2, and cGMP-dependent protein kinase Iα (cGKIα. In the absence of any one of these components, neurons in dorsal root ganglia (DRG and cranial sensory ganglia no longer bifurcate, and instead turn in either an ascending or a descending direction. In contrast, collateral axonal branch formation which represents a second type of axonal branch formation is not affected by inactivation of CNP, Npr2, or cGKI. Whereas axon bifurcation was lost in mouse mutants deficient for components of CNP-induced cGMP formation; the absence of the cGMP-degrading enzyme phosphodiesterase 2A had no effect on axon bifurcation. Adult mice that lack sensory axon bifurcation due to the conditional inactivation of Npr2-mediated cGMP signaling in DRG neurons demonstrated an altered shape of sensory axon terminal fields in the spinal cord, indicating that elaborate compensatory mechanisms reorganize neuronal circuits in the absence of bifurcation. On a functional level, these mice showed impaired heat sensation and nociception induced by chemical irritants, whereas responses to cold sensation, mechanical stimulation, and motor coordination are normal. These data point to a critical role of axon bifurcation for the processing of acute pain perception.

Action Potential Dynamics in Fine Axons Probed with an Axonally Targeted Optical Voltage Sensor.

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Ma, Yihe; Bayguinov, Peter O; Jackson, Meyer B

2017-01-01

The complex and malleable conduction properties of axons determine how action potentials propagate through extensive axonal arbors to reach synaptic terminals. The excitability of axonal membranes plays a major role in neural circuit function, but because most axons are too thin for conventional electrical recording, their properties remain largely unexplored. To overcome this obstacle, we used a genetically encoded hybrid voltage sensor (hVOS) harboring an axonal targeting motif. Expressing this probe in transgenic mice enabled us to monitor voltage changes optically in two populations of axons in hippocampal slices, the large axons of dentate granule cells (mossy fibers) in the stratum lucidum of the CA3 region and the much finer axons of hilar mossy cells in the inner molecular layer of the dentate gyrus. Action potentials propagated with distinct velocities in each type of axon. Repetitive firing broadened action potentials in both populations, but at an intermediate frequency the degree of broadening differed. Repetitive firing also attenuated action potential amplitudes in both mossy cell and granule cell axons. These results indicate that the features of use-dependent action potential broadening, and possible failure, observed previously in large nerve terminals also appear in much finer unmyelinated axons. Subtle differences in the frequency dependences could influence the propagation of activity through different pathways to excite different populations of neurons. The axonally targeted hVOS probe used here opens up the diverse repertoire of neuronal processes to detailed biophysical study.

Axon-Axon Interactions Regulate Topographic Optic Tract Sorting via CYFIP2-Dependent WAVE Complex Function.

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Cioni, Jean-Michel; Wong, Hovy Ho-Wai; Bressan, Dario; Kodama, Lay; Harris, William A; Holt, Christine E

2018-03-07

The axons of retinal ganglion cells (RGCs) are topographically sorted before they arrive at the optic tectum. This pre-target sorting, typical of axon tracts throughout the brain, is poorly understood. Here, we show that cytoplasmic FMR1-interacting proteins (CYFIPs) fulfill non-redundant functions in RGCs, with CYFIP1 mediating axon growth and CYFIP2 specifically involved in axon sorting. We find that CYFIP2 mediates homotypic and heterotypic contact-triggered fasciculation and repulsion responses between dorsal and ventral axons. CYFIP2 associates with transporting ribonucleoprotein particles in axons and regulates translation. Axon-axon contact stimulates CYFIP2 to move into growth cones where it joins the actin nucleating WAVE regulatory complex (WRC) in the periphery and regulates actin remodeling and filopodial dynamics. CYFIP2's function in axon sorting is mediated by its binding to the WRC but not its translational regulation. Together, these findings uncover CYFIP2 as a key regulatory link between axon-axon interactions, filopodial dynamics, and optic tract sorting. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Chronic intermittent hypoxia exerts CNS region-specific effects on rat microglial inflammatory and TLR4 gene expression.

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Stephanie M C Smith

Full Text Available Intermittent hypoxia (IH during sleep is a hallmark of sleep apnea, causing significant neuronal apoptosis, and cognitive and behavioral deficits in CNS regions underlying memory processing and executive functions. IH-induced neuroinflammation is thought to contribute to cognitive deficits after IH. In the present studies, we tested the hypothesis that IH would differentially induce inflammatory factor gene expression in microglia in a CNS region-dependent manner, and that the effects of IH would differ temporally. To test this hypothesis, adult rats were exposed to intermittent hypoxia (2 min intervals of 10.5% O2 for 8 hours/day during their respective sleep cycles for 1, 3 or 14 days. Cortex, medulla and spinal cord tissues were dissected, microglia were immunomagnetically isolated and mRNA levels of the inflammatory genes iNOS, COX-2, TNFα, IL-1β and IL-6 and the innate immune receptor TLR4 were compared to levels in normoxia. Inflammatory gene expression was also assessed in tissue homogenates (containing all CNS cells. We found that microglia from different CNS regions responded to IH differently. Cortical microglia had longer lasting inflammatory gene expression whereas spinal microglial gene expression was rapid and transient. We also observed that inflammatory gene expression in microglia frequently differed from that in tissue homogenates from the same region, indicating that cells other than microglia also contribute to IH-induced neuroinflammation. Lastly, microglial TLR4 mRNA levels were strongly upregulated by IH in a region- and time-dependent manner, and the increase in TLR4 expression appeared to coincide with timing of peak inflammatory gene expression, suggesting that TLR4 may play a role in IH-induced neuroinflammation. Together, these data indicate that microglial-specific neuroinflammation may play distinct roles in the effects of intermittent hypoxia in different CNS regions.

Cell-type specific expression of constitutively-active Rheb promotes regeneration of bulbospinal respiratory axons following cervical SCI.

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Urban, Mark W; Ghosh, Biswarup; Strojny, Laura R; Block, Cole G; Blazejewski, Sara M; Wright, Megan C; Smith, George M; Lepore, Angelo C

2018-05-01

Damage to respiratory neural circuitry and consequent loss of diaphragm function is a major cause of morbidity and mortality in individuals suffering from traumatic cervical spinal cord injury (SCI). Repair of CNS axons after SCI remains a therapeutic challenge, despite current efforts. SCI disrupts inspiratory signals originating in the rostral ventral respiratory group (rVRG) of the medulla from their phrenic motor neuron (PhMN) targets, resulting in loss of diaphragm function. Using a rat model of cervical hemisection SCI, we aimed to restore rVRG-PhMN-diaphragm circuitry by stimulating regeneration of injured rVRG axons via targeted induction of Rheb (ras homolog enriched in brain), a signaling molecule that regulates neuronal-intrinsic axon growth potential. Following C2 hemisection, we performed intra-rVRG injection of an adeno-associated virus serotype-2 (AAV2) vector that drives expression of a constitutively-active form of Rheb (cRheb). rVRG neuron-specific cRheb expression robustly increased mTOR pathway activity within the transduced rVRG neuron population ipsilateral to the hemisection, as assessed by levels of phosphorylated ribosomal S6 kinase. By co-injecting our novel AAV2-mCherry/WGA anterograde/trans-synaptic axonal tracer into rVRG, we found that cRheb expression promoted regeneration of injured rVRG axons into the lesion site, while we observed no rVRG axon regrowth with AAV2-GFP control. AAV2-cRheb also significantly reduced rVRG axonal dieback within the intact spinal cord rostral to the lesion. However, cRheb expression did not promote any recovery of ipsilateral hemi-diaphragm function, as assessed by inspiratory electromyography (EMG) burst amplitudes. This lack of functional recovery was likely because regrowing rVRG fibers did not extend back into the caudal spinal cord to synaptically reinnervate PhMNs that we retrogradely-labeled with cholera toxin B from the ipsilateral hemi-diaphragm. Our findings demonstrate that enhancing neuronal

Persistent Increase in Microglial RAGE Contributes to Chronic Stress-Induced Priming of Depressive-like Behavior.

Science.gov (United States)

Franklin, Tina C; Wohleb, Eric S; Zhang, Yi; Fogaça, Manoela; Hare, Brendan; Duman, Ronald S

2018-01-01

Chronic stress-induced inflammatory responses occur in part via danger-associated molecular pattern (DAMP) molecules, such as high mobility group box 1 protein (HMGB1), but the receptor(s) underlying DAMP signaling have not been identified. Microglia morphology and DAMP signaling in enriched rat hippocampal microglia were examined during the development and expression of chronic unpredictable stress (CUS)-induced behavioral deficits, including long-term, persistent changes after CUS. The results show that CUS promotes significant morphological changes and causes robust upregulation of HMGB1 messenger RNA in enriched hippocampal microglia, an effect that persists for up to 6 weeks after CUS exposure. This coincides with robust and persistent upregulation of receptor for advanced glycation end products (RAGE) messenger RNA, but not toll-like receptor 4 in hippocampal microglia. CUS also increased surface expression of RAGE protein on hippocampal microglia as determined by flow cytometry and returned to basal levels 5 weeks after CUS. Importantly, exposure to short-term stress was sufficient to increase RAGE surface expression as well as anhedonic behavior, reflecting a primed state that results from a persistent increase in RAGE messenger RNA expression. Further evidence for DAMP signaling in behavioral responses is provided by evidence that HMGB1 infusion into the hippocampus was sufficient to cause anhedonic behavior and by evidence that RAGE knockout mice were resilient to stress-induced anhedonia. Together, the results provide evidence of persistent microglial HMGB1-RAGE expression that increases vulnerability to depressive-like behaviors long after chronic stress exposure. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Macrophages Promote Axon Regeneration with Concurrent Neurotoxicity

NARCIS (Netherlands)

Gensel, J.C.; Nakamura, S.; Guan, Z.; Rooijen, van N.; Ankeny, D.P.; Popovich, P.G.

2009-01-01

Activated macrophages can promote regeneration of CNS axons. However, macrophages also release factors that kill neurons. These opposing functions are likely induced simultaneously but are rarely considered together in the same experimental preparation. A goal of this study was to unequivocally

Chronic apocynin treatment attenuates beta amyloid plaque size and microglial number in hAPP(751(SL mice.

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Melinda E Lull

Full Text Available NADPH oxidase is implicated in neurotoxic microglial activation and the progressive nature of Alzheimer's Disease (AD. Here, we test the ability of two NADPH oxidase inhibitors, apocynin and dextromethorphan (DM, to reduce learning deficits and neuropathology in transgenic mice overexpressing human amyloid precursor protein with the Swedish and London mutations (hAPP(751(SL.Four month old hAPP(751(SL mice were treated daily with saline, 15 mg/kg DM, 7.5 mg/kg DM, or 10 mg/kg apocynin by gavage for four months.Only hAPP(751(SL mice treated with apocynin showed reduced plaque size and a reduction in the number of cortical microglia, when compared to the saline treated group. Analysis of whole brain homogenates from all treatments tested (saline, DM, and apocynin demonstrated low levels of TNFα, protein nitration, lipid peroxidation, and NADPH oxidase activation, indicating a low level of neuroinflammation and oxidative stress in hAPP(751(SL mice at 8 months of age that was not significantly affected by any drug treatment. Despite in vitro analyses demonstrating that apocynin and DM ameliorate Aβ-induced extracellular superoxide production and neurotoxicity, both DM and apocynin failed to significantly affect learning and memory tasks or synaptic density in hAPP(751(SL mice. To discern how apocynin was affecting plaque levels (plaque load and microglial number in vivo, in vitro analysis of microglia was performed, revealing no apocynin effects on beta-amyloid (Aβ phagocytosis, microglial proliferation, or microglial survival.Together, this study suggests that while hAPP(751(SL mice show increases in microglial number and plaque load, they fail to exhibit elevated markers of neuroinflammation consistent with AD at 8 months of age, which may be a limitation of this animal model. Despite absence of clear neuroinflammation, apocynin was still able to reduce both plaque size and microglial number, suggesting that apocynin may have additional

Integration and long distance axonal regeneration in the central nervous system from transplanted primitive neural stem cells.

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Zhao, Jiagang; Sun, Woong; Cho, Hyo Min; Ouyang, Hong; Li, Wenlin; Lin, Ying; Do, Jiun; Zhang, Liangfang; Ding, Sheng; Liu, Yizhi; Lu, Paul; Zhang, Kang

2013-01-04

Spinal cord injury (SCI) results in devastating motor and sensory deficits secondary to disrupted neuronal circuits and poor regenerative potential. Efforts to promote regeneration through cell extrinsic and intrinsic manipulations have met with limited success. Stem cells represent an as yet unrealized therapy in SCI. Recently, we identified novel culture methods to induce and maintain primitive neural stem cells (pNSCs) from human embryonic stem cells. We tested whether transplanted human pNSCs can integrate into the CNS of the developing chick neural tube and injured adult rat spinal cord. Following injection of pNSCs into the developing chick CNS, pNSCs integrated into the dorsal aspects of the neural tube, forming cell clusters that spontaneously differentiated into neurons. Furthermore, following transplantation of pNSCs into the lesioned rat spinal cord, grafted pNSCs survived, differentiated into neurons, and extended long distance axons through the scar tissue at the graft-host interface and into the host spinal cord to form terminal-like structures near host spinal neurons. Together, these findings suggest that pNSCs derived from human embryonic stem cells differentiate into neuronal cell types with the potential to extend axons that associate with circuits of the CNS and, more importantly, provide new insights into CNS integration and axonal regeneration, offering hope for repair in SCI.

Quantifying mechanical force in axonal growth and guidance

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Ahmad Ibrahim Mahmoud Athamneh

2015-09-01

Full Text Available Mechanical force plays a fundamental role in neuronal development, physiology, and regeneration. In particular, research has shown that force is involved in growth cone-mediated axonal growth and guidance as well as stretch-induced elongation when an organism increases in size after forming initial synaptic connections. However, much of the details about the exact role of force in these fundamental processes remain unknown. In this review, we highlight (1 standing questions concerning the role of mechanical force in axonal growth and guidance and (2 different experimental techniques used to quantify forces in axons and growth cones. We believe that satisfying answers to these questions will require quantitative information about the relationship between elongation, forces, cytoskeletal dynamics, axonal transport, signaling, substrate adhesion, and stiffness contributing to directional growth advance. Furthermore, we address why a wide range of force values have been reported in the literature, and what these values mean in the context of neuronal mechanics. We hope that this review will provide a guide for those interested in studying the role of force in development and regeneration of neuronal networks.

Clinical application of three dimensional ultrafast MR imaging to intracerebral traumatic lesions

International Nuclear Information System (INIS)

Enomoto, Kyoko; Amanuma, Makoto; Hasegawa, Makoto; Watabe, Tsuneya; Heshiki, Atsuko

1994-01-01

We applied a T1-weighted three-dimensional (3D) magnetization-prepared rapid gradient-echo sequence (MPRAGE) for the detection of intracerebral lesions associated with closed head injuries. Thirty-four patients underwent brain MR imaging on a 1.5 Tesla superconducting MR unit. We applied an MPRAGE sequence, together with spin echo (SE) and gradient echo (GRE) sequences, and evaluated the detectability of lesions with each sequence. A total of 100 intracerebral traumatic lesions (33 cortical contusion, 56 diffuse axonal injury, 11 subcortical gray matter injury) were found. Ninety-seven percent of all lesions were detected on MPRAGE images, and 67% on SE and GRE images. The detectability of lesions in each category was 91%, 98%, and 100% on MPRAGE images, and 88%, 54%, and 73% on either SE or GRE images. 3D MPRAGE is a promising method to detect intracerebral traumatic lesions, particularly those associated with diffuse axonal injury, because of its high quality of contrast and spatial resolution and the capability of image reconstruction in any plane. (author)

Hyaluronic acid hydrogels with IKVAV peptides for tissue repair and axonal regeneration in an injured rat brain

International Nuclear Information System (INIS)

Wei, Y T; Tian, W M; Yu, X; Cui, F Z; Hou, S P; Xu, Q Y; Lee, In-Seop

2007-01-01

A biocompatible hydrogel of hyaluronic acid with the neurite-promoting peptide sequence of IKVAV was synthesized. The characterization of the hydrogel shows an open porous structure and a large surface area available for cell interaction. Its ability to promote tissue repair and axonal regeneration in the lesioned rat cerebrum is also evaluated. After implantation, the polymer hydrogel repaired the tissue defect and formed a permissive interface with the host tissue. Axonal growth occurred within the microstructure of the network. Within 6 weeks the polymer implant was invaded by host-derived tissue, glial cells, blood vessels and axons. Such a hydrogel matrix showed the properties of neuron conduction. It has the potential to repair tissue defects in the central nervous system by promoting the formation of a tissue matrix and axonal growth by replacing the lost tissue

GSK3 controls axon growth via CLASP-mediated regulation of growth cone microtubules

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Hur, Eun-Mi; Saijilafu; Lee, Byoung Dae; Kim, Seong-Jin; Xu, Wen-Lin; Zhou, Feng-Quan

2011-01-01

Suppression of glycogen synthase kinase 3 (GSK3) activity in neurons yields pleiotropic outcomes, causing both axon growth promotion and inhibition. Previous studies have suggested that specific GSK3 substrates, such as adenomatous polyposis coli (APC) and collapsin response mediator protein 2 (CRMP2), support axon growth by regulating the stability of axonal microtubules (MTs), but the substrate(s) and mechanisms conveying axon growth inhibition remain elusive. Here we show that CLIP (cytoplasmic linker protein)-associated protein (CLASP), originally identified as a MT plus end-binding protein, displays both plus end-binding and lattice-binding activities in nerve growth cones, and reveal that the two MT-binding activities regulate axon growth in an opposing manner: The lattice-binding activity mediates axon growth inhibition induced by suppression of GSK3 activity via preventing MT protrusion into the growth cone periphery, whereas the plus end-binding property supports axon extension via stabilizing the growing ends of axonal MTs. We propose a model in which CLASP transduces GSK3 activity levels to differentially control axon growth by coordinating the stability and configuration of growth cone MTs. PMID:21937714

Glia to axon RNA transfer.

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Sotelo, José Roberto; Canclini, Lucía; Kun, Alejandra; Sotelo-Silveira, José Roberto; Calliari, Aldo; Cal, Karina; Bresque, Mariana; Dipaolo, Andrés; Farias, Joaquina; Mercer, John A

2014-03-01

The existence of RNA in axons has been a matter of dispute for decades. Evidence for RNA and ribosomes has now accumulated to a point at which it is difficult to question, much of the disputes turned to the origin of these axonal RNAs. In this review, we focus on studies addressing the origin of axonal RNAs and ribosomes. The neuronal soma as the source of most axonal RNAs has been demonstrated and is indisputable. However, the surrounding glial cells may be a supplemental source of axonal RNAs, a matter scarcely investigated in the literature. Here, we review the few papers that have demonstrated that glial-to-axon RNA transfer is not only feasible, but likely. We describe this process in both invertebrate axons and vertebrate axons. Schwann cell to axon ribosomes transfer was conclusively demonstrated (Court et al. [2008]: J. Neurosci 28:11024-11029; Court et al. [2011]: Glia 59:1529-1539). However, mRNA transfer still remains to be demonstrated in a conclusive way. The intercellular transport of mRNA has interesting implications, particularly with respect to the integration of glial and axonal function. This evolving field is likely to impact our understanding of the cell biology of the axon in both normal and pathological conditions. Most importantly, if the synthesis of proteins in the axon can be controlled by interacting glia, the possibilities for clinical interventions in injury and neurodegeneration are greatly increased. Copyright © 2013 Wiley Periodicals, Inc.

The genetics of axonal transport and axonal transport disorders.

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Jason E Duncan

2006-09-01

Full Text Available Neurons are specialized cells with a complex architecture that includes elaborate dendritic branches and a long, narrow axon that extends from the cell body to the synaptic terminal. The organized transport of essential biological materials throughout the neuron is required to support its growth, function, and viability. In this review, we focus on insights that have emerged from the genetic analysis of long-distance axonal transport between the cell body and the synaptic terminal. We also discuss recent genetic evidence that supports the hypothesis that disruptions in axonal transport may cause or dramatically contribute to neurodegenerative diseases.

Radiation-induced intestinal lesions. Prognosis and surgical management

International Nuclear Information System (INIS)

Van Haecke, P.; Vitaux, J.; Michot, F.; Hay, J.-M.; Flamant, Y.; Maillard, J.-N.

1981-01-01

Thirteen patients with intestinal lesions consecutive to radiotherapy for carcinoma of the uterus were operated upon between 1973 and 1979. The small bowel was involved in 9 patients and the colon and rectum in 4 patients. Urinary tract lesions were associated in 3 patients of each group. Intestinal necrosis, progression of the lesions and extensive pelvic fibrosis were the only criteria of poor prognosis. Twenty-two operations were performed: 4 for urinary tract lesions and 18 for intestinal lesions. Five patients died during the immediate post-operative period and five died within 2 to 30 months after surgery, including 4 whose carcinoma recurred. The operative technique should be selected according to the extent and severity of radiation-induced damage, as determined by pre-operative examination and thorough exploration of the abdominal cavity once opened. Limited lesions of the small bowel can be treated by resection, but intestinal bypass with latero-lateral anastomosis seems to be preferable in cases with extensive lesions. Patients with colorectal lesions should have defunctioning colostomy prior to any other procedure dictated by the state of affairs. Multiple anastomosis, extensive resections and excessive dissections should be avoided [fr

Self-Assembling Peptide Nanofiber Scaffold Enhanced with RhoA Inhibitor CT04 Improves Axonal Regrowth in the Transected Spinal Cord

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Weiwei Zhang

2012-01-01

Full Text Available The present study was designed to explore the therapeutic potential of self-assembling peptide nanofiber scaffold (SAPNS delivered RhoA inhibitor to ameliorate the hostile microenvironment of injured spinal cord for axonal regeneration. After a transection was applied to the thoracic spinal cord of mice, the combination of SAPNS and CT04 (a cell permeable RhoA inhibitor, single SAPNS with vehicle, or saline was transplanted into the lesion cavity. Results showed that SAPNS+CT04 implants achieved the best therapeutic outcomes among treatment groups. The novel combination not only reconstructed the injured nerve gap but also elicited significant axonal regeneration and motor functional recovery. Additionally, the combination also effectively reduced the apoptosis and infiltration of activated macrophages in the injured spinal cord. Collectively, the present study demonstrated that SAPNS-based delivery of RhoA inhibitor CT04 presented a highly potential therapeutic strategy for spinal cord injury with reknitting lesion gap, attenuating secondary injury, and improving axonal regrowth.

Self-Assembling Peptide Nanofiber Scaffold Enhanced with RhoA Inhibitor CT04 Improves Axonal Regrowth in the Transected Spinal Cord

International Nuclear Information System (INIS)

Weiwei, Z.; Xiaoduo, Z.; Zhongying, L.

2012-01-01

The present study was designed to explore the therapeutic potential of self-assembling peptide nano fiber scaffold (SAPNS) delivered RhoA inhibitor to ameliorate the hostile microenvironment of injured spinal cord for axonal regeneration. After a transection was applied to the thoracic spinal cord of mice, the combination of SAPNS and CT04 (a cell permeable RhoA inhibitor), single SAPNS with vehicle, or saline was transplanted into the lesion cavity. Results showed that SAPNS+CT04 implants achieved the best therapeutic outcomes among treatment groups. The novel combination not only reconstructed the injured nerve gap but also elicited significant axonal regeneration and motor functional recovery. Additionally, the combination also effectively reduced the apoptosis and infiltration of activated macrophages in the injured spinal cord. Collectively, the present study demonstrated that SAPNS-based delivery of RhoA inhibitor CT04 presented a highly potential therapeutic strategy for spinal cord injury with reknitting lesion gap, attenuating secondary injury, and improving axonal regrowth.

Lesion bacterial communities in American lobsters with diet-induced shell disease.

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Quinn, Robert A; Metzler, Anita; Tlusty, Michael; Smolowitz, Roxanna M; Leberg, Paul; Chistoserdov, Andrei Y

2012-04-26

In southern New England, USA, shell disease affects the profitability of the American lobster Homarus americanus fishery. In laboratory trials using juvenile lobsters, exclusive feeding of herring Clupea harengus induces shell disease typified initially by small melanized spots that progress into distinct lesions. Amongst a cohabitated, but segregated, cohort of 11 juvenile lobsters fed exclusively herring, bacterial communities colonizing spots and lesions were investigated by denaturing gradient gel electrophoresis of 16S rDNA amplified using 1 group-specific and 2 universal primer sets. The Bacteroidetes and Proteobacteria predominated in both spots and lesions and included members of the orders Flavobacteriales (Bacteriodetes), Rhodobacterales, Rhodospirillales and Rhizobiales (Alphaproteobacteria), Xanthomonadales (Gammaproteobacteria) and unclassified Gammaproteobacteria. Bacterial communities in spot lesions displayed more diversity than communities with larger (older) lesions, indicating that the lesion communities stabilize over time. At least 8 bacterial types persisted as lesions developed from spots. Aquimarina 'homaria', a species commonly cultured from lesions present on wild lobsters with epizootic shell disease, was found ubiquitously in spots and lesions, as was the 'Candidatus Kopriimonas aquarianus', implicating putative roles of these species in diet-induced shell disease of captive lobsters.

Neuroimmune regulation of microglial activity involved in neuroinflammation and neurodegenerative diseases.

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González, Hugo; Elgueta, Daniela; Montoya, Andro; Pacheco, Rodrigo

2014-09-15

Neuroinflammation constitutes a fundamental process involved in the progression of several neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis and multiple sclerosis. Microglial cells play a central role in neuroinflammation, promoting neuroprotective or neurotoxic microenvironments, thus controlling neuronal fate. Acquisition of different microglial functions is regulated by intercellular interactions with neurons, astrocytes, the blood-brain barrier, and T-cells infiltrating the central nervous system. In this study, an overview of the regulation of microglial function mediated by different intercellular communications is summarised and discussed. Afterward, we focus in T-cell-mediated regulation of neuroinflammation involved in neurodegenerative disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

Microglial Dysregulation in OCD, Tourette Syndrome, and PANDAS

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Luciana Frick

2016-01-01

Full Text Available There is accumulating evidence that immune dysregulation contributes to the pathophysiology of obsessive-compulsive disorder (OCD, Tourette syndrome, and Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS. The mechanistic details of this pathophysiology, however, remain unclear. Here we focus on one particular component of the immune system: microglia, the brain’s resident immune cells. The role of microglia in neurodegenerative diseases has been understood in terms of classic, inflammatory activation, which may be both a consequence and a cause of neuronal damage. In OCD and Tourette syndrome, which are not characterized by frank neural degeneration, the potential role of microglial dysregulation is much less clear. Here we review the evidence for a neuroinflammatory etiology and microglial dysregulation in OCD, Tourette syndrome, and PANDAS. We also explore new hypotheses as to the potential contributions of microglial abnormalities to pathophysiology, beyond neuroinflammation, including failures in neuroprotection, lack of support for neuronal survival, and abnormalities in synaptic pruning. Recent advances in neuroimaging and animal model work are creating new opportunities to elucidate these issues.

Microglial Dysregulation in OCD, Tourette Syndrome, and PANDAS

Science.gov (United States)

2016-01-01

There is accumulating evidence that immune dysregulation contributes to the pathophysiology of obsessive-compulsive disorder (OCD), Tourette syndrome, and Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). The mechanistic details of this pathophysiology, however, remain unclear. Here we focus on one particular component of the immune system: microglia, the brain's resident immune cells. The role of microglia in neurodegenerative diseases has been understood in terms of classic, inflammatory activation, which may be both a consequence and a cause of neuronal damage. In OCD and Tourette syndrome, which are not characterized by frank neural degeneration, the potential role of microglial dysregulation is much less clear. Here we review the evidence for a neuroinflammatory etiology and microglial dysregulation in OCD, Tourette syndrome, and PANDAS. We also explore new hypotheses as to the potential contributions of microglial abnormalities to pathophysiology, beyond neuroinflammation, including failures in neuroprotection, lack of support for neuronal survival, and abnormalities in synaptic pruning. Recent advances in neuroimaging and animal model work are creating new opportunities to elucidate these issues. PMID:28053994

Microglial responses to amyloid β peptide opsonization and indomethacin treatment

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Leonard Brian

2005-08-01

Full Text Available Abstract Background Recent studies have suggested that passive or active immunization with anti-amyloid β peptide (Aβ antibodies may enhance microglial clearance of Aβ deposits from the brain. However, in a human clinical trial, several patients developed secondary inflammatory responses in brain that were sufficient to halt the study. Methods We have used an in vitro culture system to model the responses of microglia, derived from rapid autopsies of Alzheimer's disease patients, to Aβ deposits. Results Opsonization of the deposits with anti-Aβ IgG 6E10 enhanced microglial chemotaxis to and phagocytosis of Aβ, as well as exacerbated microglial secretion of the pro-inflammatory cytokines TNF-α and IL-6. Indomethacin, a common nonsteroidal anti-inflammatory drug (NSAID, had no effect on microglial chemotaxis or phagocytosis, but did significantly inhibit the enhanced production of IL-6 after Aβ opsonization. Conclusion These results are consistent with well known, differential NSAID actions on immune cell functions, and suggest that concurrent NSAID administration might serve as a useful adjunct to Aβ immunization, permitting unfettered clearance of Aβ while dampening secondary, inflammation-related adverse events.

RECENT ADVANCES IN STRATEGIES FOR IMMUNOTHERAPY OF HUMAN PAPILLOMAVIRUS-INDUCED LESIONS

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Kanodia, Shreya; Da Silva, Diane M.; Kast, W. Martin

2016-01-01

Human papillomavirus (HPV)-induced lesions are distinct in that they have targetable foreign antigens, the expression of which is necessary to maintain the cancerous phenotype. Hence, they pose as a very attractive target for “proof of concept” studies in the development of therapeutic vaccines. This review will focus on the most recent clinical trials for the immunotherapy of mucosal and cutaneous HPV-induced lesions as well as emerging therapeutic strategies that have been tested in pre-clinical models for HPV-induced lesions. Progress in peptide-based vaccines, DNA-based vaccines, viral/bacterial vector-based vaccines, immune response modifiers, photodynamic therapy and T cell receptor based therapy for HPV will be discussed. PMID:17973257

CCL2/MCP-1 modulation of microglial activation and proliferation

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Garcia-Bueno Borja

2011-07-01

Full Text Available Abstract Background Monocyte chemoattractant protein (CCL2/MCP-1 is a chemokine that attracts cells involved in the immune/inflammatory response. As microglia are one of the main cell types sustaining inflammation in brain, we proposed here to analyze the direct effects of MCP-1 on cultured primary microglia. Methods Primary microglia and neuronal cultures were obtained from neonatal and embryonic Wistar rats, respectively. Microglia were incubated with different concentrations of recombinant MCP-1 and LPS. Cell proliferation was quantified by measuring incorporation of bromodeoxyuridine (BrdU. Nitrite accumulation was measured using the Griess assay. The expression and synthesis of different proteins was measured by RT-PCR and ELISA. Cell death was quantified by measuring release of LDH into the culture medium. Results MCP-1 treatment (50 ng/ml, 24 h did not induce morphological changes in microglial cultures. Protein and mRNA levels of different cytokines were measured, showing that MCP-1 was not able to induce proinflammatory cytokines (IL-1β, IL6, MIP-1α, either by itself or in combination with LPS. A similar lack of effect was observed when measuring inducible nitric oxide synthase (NOS2 expression or accumulation of nitrites in the culture media as a different indicator of microglial activation. MCP-1 was also unable to alter the expression of different trophic factors that were reduced by LPS treatment. In order to explore the possible release of other products by microglia and their potential neurotoxicity, neurons were co-cultured with microglia: no death of neurons could be detected when treated with MCP-1. However, the presence of MCP-1 induced proliferation of microglia, an effect opposite to that observed with LPS. Conclusion These data indicate that, while causing migration and proliferation of microglia, MCP-1 does not appear to directly activate an inflammatory response in this cell type, and therefore, other factors may be

The Molecular and Cellular Mechanisms of Axon Guidance in Mossy Fiber Sprouting

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Ryuta Koyama

2018-05-01

Full Text Available The question of whether mossy fiber sprouting is epileptogenic has not been resolved; both sprouting-induced recurrent excitatory and inhibitory circuit hypotheses have been experimentally (but not fully supported. Therefore, whether mossy fiber sprouting is a potential therapeutic target for epilepsy remains under debate. Moreover, the axon guidance mechanisms of mossy fiber sprouting have attracted the interest of neuroscientists. Sprouting of mossy fibers exhibits several uncommon axonal growth features in the basically non-plastic adult brain. For example, robust branching of axonal collaterals arises from pre-existing primary mossy fiber axons. Understanding the branching mechanisms in adulthood may contribute to axonal regeneration therapies in neuroregenerative medicine in which robust axonal re-growth is essential. Additionally, because granule cells are produced throughout life in the neurogenic dentate gyrus, it is interesting to examine whether the mossy fibers of newly generated granule cells follow the pre-existing trajectories of sprouted mossy fibers in the epileptic brain. Understanding these axon guidance mechanisms may contribute to neuron transplantation therapies, for which the incorporation of transplanted neurons into pre-existing neural circuits is essential. Thus, clarifying the axon guidance mechanisms of mossy fiber sprouting could lead to an understanding of central nervous system (CNS network reorganization and plasticity. Here, we review the molecular and cellular mechanisms of axon guidance in mossy fiber sprouting by discussing mainly in vitro studies.

Nephroprotective and anti-inflammatory effects of aqueous extract of Melissa officinalis L. on acetaminophen-induced and pleurisy-induced lesions in rats

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Denise Pereira Müzell

2013-06-01

Full Text Available This study assessed the bioactive properties of an aqueous extract of M. officinalis for its anti-inflammatory activity and its protection against hepatic and renal lesions induced by acetaminophen (APAP. Animals pre-treated with the crude extract in pleurisy induced by carrageenan showed a reduction in the amounts of exudate, in the numbers of leukocytes and polymorphonuclear cells. Intragastric administration of the extract for seven days prior to the APAP-induced lesion showed no protective effect on the liver. The treatment with the extract induced an increase of serum aspartate aminotransferase, indicating a rise of toxicity. Contrarily, the same treatment reduced the APAP induced lesion in kidney, with respect to ν-glutamyltransferase. The results suggested that the extract was not hepatoprotective and could lead to an increase in the lesions induced by the APAP. On the other hand, the extract was nephroprotective against the lesions induced by the APAP and showed an anti-inflammatory effect on pleurisy carrageenan-induced.

A Correlative Study of Smokeless Tobacco induced Lesion and Smoke-induced Leukoplakia in Various Aspects

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Parita K Chitroda

2011-01-01

Full Text Available Various oral mucosal lesions are attributed to tobacco use. The presence of these conditions vanes with particular type of tobacco used (smoking or smokeless and the form in which it is used, such as cigarettes, pipes, cigars and chewing moist snuff. The frequency and duration of use as well as the ways in which the tobacco product is used also contributes to the clinical presentation and seventy of the lesion. The present study is mainly focused on the correlation between the smokeless tobacco-induced lesion and smoke-induced leukoplakia on various aspects with an objective to determine smokeless tobacco as a possible cause for leukoplakia.

Dextromethorphan inhibition of voltage-gated proton currents in BV2 microglial cells.

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Song, Jin-Ho; Yeh, Jay Z

2012-05-10

Dextromethorphan, an antitussive drug, has a neuroprotective property as evidenced by its inhibition of microglial production of pro-inflammatory cytokines and reactive oxygen species. The microglial activation requires NADPH oxidase activity, which is sustained by voltage-gated proton channels in microglia as they dissipate an intracellular acid buildup. In the present study, we examined the effect of dextromethorphan on proton currents in microglial BV2 cells. Dextromethorphan reversibly inhibited proton currents with an IC(50) value of 51.7 μM at an intracellular/extracellular pH gradient of 5.5/7.3. Dextromethorphan did not change the reversal potential or the voltage dependence of the gating. Dextrorphan and 3-hydroxymorphinan, major metabolites of dextromethorphan, and dextromethorphan methiodide were ineffective in inhibiting proton currents. The results indicate that dextromethorphan inhibition of proton currents would suppress NADPH oxidase activity and, eventually, microglial activation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Photothermal lesions in soft tissue induced by optical fiber microheaters.

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Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

2016-04-01

Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy.

Classification of acquired lesions of the corpus callosum with MRI

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Friese, S.A.; Bitzer, M.; Voigt, K.; Kueker, W. [Tuebingen Univ. (Germany). Abt. fuer Neuroradiologie; Freudenstein, D. [Department of Neurosurgery, Eberhard-Karls-University Tuebingen (Germany)

2000-11-01

MRI has facilitated diagnostic assessment of the corpus callosum. Diagnostic classification of solitary or multiple lesions of the corpus callosum has not attracted much attention, although signal abnormalities are not uncommon. Our aim was to identify characteristic imaging features of lesions frequently encountered in practice. We reviewed the case histories of 59 patients with lesions shown on MRI. The nature of the lesions was based on clinical features and/or long term follow-up (ischaemic 20, Virchow-Robin spaces 3, diffuse axonal injury 7, multiple sclerosis 11, hydrocephalus 5, acute disseminated encephalomyelitis 5, Marchiafava-Bignami disease 4, lymphoma 2, glioblastoma hamartoma each 1). The location in the sagittal plane, the relationship to the borders of the corpus callosum and midline and the size were documented. The 20 ischaemic lesions were asymmetrical but adjacent to the midline; the latter was involved in new or large lesions. Diffuse axonal injury commonly resulted in large lesions, which tended to be asymmetrical; the midline and borders of the corpus callosum were always involved. Lesions in MS were small, at the lower border of the corpus callosum next to the septum pellucidum, and crossed the midline asymmetrically. Acute disseminated encephalomyelitis and the other perivenous inflammatory diseases caused relatively large, asymmetrical lesions. Hydrocephalus resulted in lesions of the upper part of the corpus callosum, and mostly in its posterior two thirds; they were found in the midline. Lesions in Marchiafava-Bignami disease were large, often symmetrically in the midline in the splenium and did not reach the edge of the corpus callosum. (orig.)

DNA lesions induced by replication stress trigger mitotic aberration and tetraploidy development.

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Yosuke Ichijima

Full Text Available During tumorigenesis, cells acquire immortality in association with the development of genomic instability. However, it is still elusive how genomic instability spontaneously generates during the process of tumorigenesis. Here, we show that precancerous DNA lesions induced by oncogene acceleration, which induce situations identical to the initial stages of cancer development, trigger tetraploidy/aneuploidy generation in association with mitotic aberration. Although oncogene acceleration primarily induces DNA replication stress and the resulting lesions in the S phase, these lesions are carried over into the M phase and cause cytokinesis failure and genomic instability. Unlike directly induced DNA double-strand breaks, DNA replication stress-associated lesions are cryptogenic and pass through cell-cycle checkpoints due to limited and ineffective activation of checkpoint factors. Furthermore, since damaged M-phase cells still progress in mitotic steps, these cells result in chromosomal mis-segregation, cytokinesis failure and the resulting tetraploidy generation. Thus, our results reveal a process of genomic instability generation triggered by precancerous DNA replication stress.

Calpain Inhibition Reduces Axolemmal Leakage in Traumatic Axonal Injury

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János Sándor

2009-12-01

Full Text Available Calcium-induced, calpain-mediated proteolysis (CMSP has recently been implicated to the pathogenesis of diffuse (traumatic axonal injury (TAI. Some studies suggested that subaxolemmal CMSP may contribute to axolemmal permeability (AP alterations observed in TAI. Seeking direct evidence for this premise we investigated whether subaxolemmal CMSP may contribute to axolemmal permeability alterations (APA and pre-injury calpain-inhibition could reduce AP in a rat model of TAI. Horseradish peroxidase (HRP, a tracer that accumulates in axons with APA was administered one hour prior to injury into the lateral ventricle; 30 min preinjury a single tail vein bolus injection of 30 mg/kg MDL-28170 (a calpain inhibitor or its vehicle was applied in Wistar rats exposed to impact acceleration brain injury. Histological detection of traumatically injured axonal segments accumulating HRP and statistical analysis revealed that pre-injury administration of the calpain inhibitor MDL-28170 significantly reduced the average length of HRP-labeled axonal segments. The axono-protective effect of pre-injury calpain inhibition recently demonstrated with classical immunohistochemical markers of TAI was further corroborated in this experiment; significant reduction of the length of labeled axons in the drug-treated rats implicate CMSP in the progression of altered AP in TAI.

Lesions of the lateral hypothalamus impair pilocarpine-induced salivation in rats.

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Renzi, A; De Luca, L A; Menani, J V

2002-09-15

In the present study we investigated the effects of electrolytic lesions of the lateral hypothalamus (LH) in the salivation induced by intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) injection of the cholinergic agonist pilocarpine. Rats with sham or LH lesions and stainless steel cannulas implanted into the lateral ventricle (LV) were used. In rats anesthetized with urethane (1.25mg/kg of body weight) saliva was collected using pre-weighed cotton balls inserted in the animal mouth during a period of 7 min following i.c.v. or i.p. injection of pilocarpine. Injection of pilocarpine (1mg/kg of body weight) i.p. in sham-operated rats (6h, 2, 7, and 15 days after the surgery) induced salivation (497+/-24, 452+/-26, 476+/-30, and 560+/-75 mg/7 min, respectively). The effects of i.p. pilocarpine was reduced 6h, 2 and 7 days after LH lesions (162+/-37, 190+/-32, and 229+/-27 mg/7 min, respectively), not 15 days after LH lesions (416+/-89 mg/7 min). Injection of pilocarpine (120 micro g/micro l) i.c.v., in sham-operated rats (6h, 2, 7, and 15 days after the surgery) also produced salivation (473+/-20, 382+/-16, 396+/-14, and 427+/-47 mg/7 min, respectively). The salivation induced by i.c.v. pilocarpine was also reduced 6h, 2 and 7 days after LH lesions (243+/-19, 278+/-24, and 295+/-27 mg/7 min, respectively), not 15 days after LH lesions (385+/-48 mg/7 min). The present results show the participation of the LH in the salivation induced by central or peripheral injection of pilocarpine in rats, reinforcing the involvement of central mechanisms on pilocarpine-induced salivation.

Lesion-induced pseudo-dominance at functional magnetic resonance imaging: implications for preoperative assessments.

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Ulmer, John L; Hacein-Bey, Lotfi; Mathews, Vincent P; Mueller, Wade M; DeYoe, Edgar A; Prost, Robert W; Meyer, Glenn A; Krouwer, Hendrikus G; Schmainda, Kathleen M

2004-09-01

To illustrate how lesion-induced neurovascular uncoupling at functional magnetic resonance imaging (fMRI) can mimic hemispheric dominance opposite the side of a lesion preoperatively. We retrospectively reviewed preoperative fMRI mapping data from 50 patients with focal brain abnormalities to establish patterns of hemispheric dominance of language, speech, visual, or motor system functions. Abnormalities included gliomas (31 patients), arteriovenous malformations (AVMs) (11 patients), other congenital lesions (4 patients), encephalomalacia (3 patients), and tumefactive encephalitis (1 patient). A laterality ratio of fMRI hemispheric dominance was compared with actual hemispheric dominance as verified by electrocortical stimulation, Wada testing, postoperative and posttreatment deficits, and/or lesion-induced deficits. fMRI activation maps were generated with cross-correlation (P frontal gyrus gliomas and in one patient with focal tumefactive meningoencephalitis, fMRI incorrectly suggested strong right hemispheric speech dominance. In two patients with lateral precentral gyrus region gliomas and one patient with a left central sulcus AVM, the fMRI pattern incorrectly suggested primary corticobulbar motor dominance contralateral to the side of the lesion. In a patient with a right superior frontal gyrus AVM, fMRI revealed pronounced left dominant supplementary motor area activity in response to a bilateral complex motor task, but right superior frontal gyrus perilesional hemorrhage and edema subsequently caused left upper-extremity plegia. Pathophysiological factors that might have caused neurovascular uncoupling and facilitated pseudo-dominance at fMRI in these patients included direct tumor infiltration, neovascularity, cerebrovascular inflammation, and AVM-induced hemodynamic effects. Sixteen patients had proven (1 patient), probable (2 patients), or possible (13 patients) but unproven lesion-induced homotopic cortical reorganization. Lesion-induced neurovascular

Piezoelectric ceramic (PZT) modulates axonal guidance growth of rat cortical neurons via RhoA, Rac1, and Cdc42 pathways.

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Wen, Jianqiang; Liu, Meili

2014-03-01

Electrical stimulation is critical for axonal connection, which can stimulate axonal migration and deformation to promote axonal growth in the nervous system. Netrin-1, an axonal guidance cue, can also promote axonal guidance growth, but the molecular mechanism of axonal guidance growth under indirect electric stimulation is still unknown. We investigated the molecular mechanism of axonal guidance growth under piezoelectric ceramic lead zirconate titanate (PZT) stimulation in the primary cultured cortical neurons. PZT induced marked axonal elongation. Moreover, PZT activated the excitatory postsynaptic currents (EPSCs) by increasing the frequency and amplitude of EPSCs of the cortical neurons in patch clamp assay. PZT downregulated the expression of Netrin-1 and its receptor Deleted in Colorectal Cancer (DCC). Rho GTPase signaling is involved in interactions of Netrin-1 and DCC. PZT activated RhoA. Dramatic decrease of Cdc42 and Rac1 was also observed after PZT treatment. RhoA inhibitor Clostridium botulinum C3 exoenzyme (C3-Exo) prevented the PZT-induced downregulation of Netrin-1 and DCC. We suggest that PZT can promote axonal guidance growth by downregulation of Netrin-1 and DCC to mediate axonal repulsive responses via the Rho GTPase signaling pathway. Obviously, piezoelectric materials may provide a new approach for axonal recovery and be beneficial for clinical therapy in the future.

Retinal ganglion cell survival and axon regeneration after optic nerve injury in naked mole-rats.

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Park, Kevin K; Luo, Xueting; Mooney, Skyler J; Yungher, Benjamin J; Belin, Stephane; Wang, Chen; Holmes, Melissa M; He, Zhigang

2017-02-01

In the adult mammalian central nervous system (CNS), axonal damage often triggers neuronal cell death and glial activation, with very limited spontaneous axon regeneration. In this study, we performed optic nerve injury in adult naked mole-rats, the longest living rodent, with a maximum life span exceeding 30 years, and found that injury responses in this species are quite distinct from those in other mammalian species. In contrast to what is seen in other mammals, the majority of injured retinal ganglion cells (RGCs) survive with relatively high spontaneous axon regeneration. Furthermore, injured RGCs display activated signal transducer and activator of transcription-3 (STAT3), whereas astrocytes in the optic nerve robustly occupy and fill the lesion area days after injury. These neuron-intrinsic and -extrinsic injury responses are reminiscent of those in "cold-blooded" animals, such as fish and amphibians, suggesting that the naked mole-rat is a powerful model for exploring the mechanisms of neuronal injury responses and axon regeneration in mammals. J. Comp. Neurol. 525:380-388, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Maternal immune activation results in complex microglial transcriptome signature in the adult offspring that is reversed by minocycline treatment

NARCIS (Netherlands)

Mattei, D.; Ivanov, A.; Ferrai, C.; Jordan, P.; Guneykaya, D.; Buonfiglioli, A.; Schaafsma, W.; Przanowski, P.; Deuther-Conrad, W.; Brust, P.; Hesse, S.; Patt, M.; Sabri, O.; Ross, T. L.; Eggen, B. J. L.; Boddeke, E. W. G. M.; Kaminska, B.; Beule, D.; Pombo, A.; Kettenmann, H.; Wolf, S. A.

2017-01-01

Maternal immune activation (MIA) during pregnancy has been linked to an increased risk of developing psychiatric pathologies in later life. This link may be bridged by a defective microglial phenotype in the offspring induced by MIA, as microglia have key roles in the development and maintenance of

Extracellular Tau Oligomers Induce Invasion of Endogenous Tau into the Somatodendritic Compartment and Axonal Transport Dysfunction

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Swanson, Eric; Breckenridge, Leigham; McMahon, Lloyd; Som, Sreemoyee; McConnell, Ian; Bloom, George S.

2017-01-01

Aggregates composed of the microtubule associated protein, tau, are a hallmark of Alzheimer’s disease and non-Alzheimer’s tauopathies. Extracellular tau can induce the accumulation and aggregation of intracellular tau, and tau pathology can be transmitted along neural networks over time. There are six splice variants of central nervous system tau, and various oligomeric and fibrillar forms are associated with neurodegeneration in vivo. The particular extracellular forms of tau capable of transferring tau pathology from neuron to neuron remain ill defined, however, as do the consequences of intracellular tau aggregation on neuronal physiology. The present study was undertaken to compare the effects of extracellular tau monomers, oligomers, and filaments comprising various tau isoforms on the behavior of cultured neurons. We found that 2N4R or 2N3R tau oligomers provoked aggregation of endogenous intracellular tau much more effectively than monomers or fibrils, or of oligomers made from other tau isoforms, and that a mixture of all six isoforms most potently provoked intracellular tau accumulation. These effects were associated with invasion of tau into the somatodendritic compartment. Finally, we observed that 2N4R oligomers perturbed fast axonal transport of membranous organelles along microtubules. Intracellular tau accumulation was often accompanied by increases in the run length, run time and instantaneous velocity of membranous cargo. This work indicates that extracellular tau oligomers can disrupt normal neuronal homeostasis by triggering axonal tau accumulation and loss of the polarized distribution of tau, and by impairing fast axonal transport. PMID:28482642

Glioma-secreted soluble factors stimulate microglial activation: The role of interleukin-1β and tumor necrosis factor-α.

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Hwang, Ji-Sun; Jung, Eun-Hye; Kwon, Mi-Youn; Han, Inn-Oc

2016-09-15

We aimed to elucidate the effect of soluble factors secreted by glioma on microglial activation. Conditioned medium (CM) from glioma cells, CRT-MG and C6, significantly induced nitric oxide (NO) production and stimulated the mRNA expression of inducible NO synthase (iNOS), interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha (TNF-α) and cyclooxygenase 2 (COX-2) in BV2 cells. Glioma CM stimulated p38 mitogen-activated protein kinase (MAPK) phosphorylation, and a p38 MAPK inhibitor, SB203580, suppressed CM-induced NO production in BV2 cells. In addition, CM stimulated nuclear factor-kappaB (NF-κB) DNA binding and transcriptional activity, which was repressed by SB203580. Gliomas displayed higher mRNA expression and release of TNF-α and IL-1β than primary astrocyte cells. Neutralization of TNF-α and IL-1β in C6-CM using a neutralizing antibody inhibited NO/iNOS expression in BV-2 cells. These results indicate potential contribution of diffusible tumor-derived factors to regulate microglial activation and subsequent tumor microenvironment. Copyright © 2016. Published by Elsevier B.V.

Functional Impact of Corticotropin-Releasing Factor Exposure on Tau Phosphorylation and Axon Transport.

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Michelle H Le

Full Text Available Stress exposure or increased levels of corticotropin-releasing factor (CRF induce hippocampal tau phosphorylation (tau-P in rodent models, a process that is dependent on the type-1 CRF receptor (CRFR1. Although these preclinical studies on stress-induced tau-P provide mechanistic insight for epidemiological work that identifies stress as a risk factor for Alzheimer's disease (AD, the actual impact of stress-induced tau-P on neuronal function remains unclear. To determine the functional consequences of stress-induced tau-P, we developed a novel mouse neuronal cell culture system to explore the impact of acute (0.5hr and chronic (2hr CRF treatment on tau-P and integral cell processes such as axon transport. Consistent with in vivo reports, we found that chronic CRF treatment increased tau-P levels and caused globular accumulations of phosphorylated tau in dendritic and axonal processes. Furthermore, while both acute and chronic CRF treatment led to significant reduction in CREB activation and axon transport of brain-derived neurotrophic factor (BDNF, this was not the case with mitochondrial transport. Acute CRF treatment caused increased mitochondrial velocity and distance traveled in neurons, while chronic CRF treatment modestly decreased mitochondrial velocity and greatly increased distance traveled. These results suggest that transport of cellular energetics may take priority over growth factors during stress. Tau-P was required for these changes, as co-treatment of CRF with a GSK kinase inhibitor prevented CRF-induced tau-P and all axon transport changes. Collectively, our results provide mechanistic insight into the consequences of stress peptide-induced tau-P and provide an explanation for how chronic stress via CRF may lead to neuronal vulnerability in AD.

Lesions induced in rodent pancreas by azaserine and other pancreatic carcinogens

Energy Technology Data Exchange (ETDEWEB)

Longnecker, D.S.

1984-06-01

Focal proliferative changes in the acinar cells of the pancreas of rats have been induced by several systemically administered carcinogens including azaserine, N-nitrosobis(2-oxopropyl)amine, N-nitroso(2-hydroxypropyl) (2-oxopropyl)amine, and Ndelta-(N-methyl-N-nitrosocarbamoyl)-L-ornithine (MNCO). Foci, nodules, and adenomas induced by these carcinogens are usually made up of atypical-appearing acinar cells that maintain a high degree of differentiation, but a minority of these lesions exhibit anaplastic cellular changes that suggest the development of malignant potential. Such anaplasia may occupy the whole of smaller lesions or may occur as a secondary focal change within larger nodules or adenomas. Many foci and nodules per pancreas have been induced by single or multiple exposures to these known genotoxic carcinogens, but relatively few of them develop into carcinomas. Azaserine and MNCO have induced acinar cell carcinomas in rats. Those induced by azaserine have exhibited a broad spectrum of histologic variants, including ductlike, cystic and undifferentiated patterns. Higher doses of MNCO have induced a second pattern of change in the pancreatic lobules of rats, which includes cystic and tubular ductlike structures that have been called cystic and tubular ductal complexes. MNCO has also induced focal acinar cell lesions, cystic and tubular ductal complexes, and adenocarcinomas in the pancreas of Syrian golden hamsters. In this species, ductal complexes are much more numerous than are proliferative lesions of acinar cells, and the histologic appearance of the carcinomas is ductlike. Hyperplasia and atypical changes were also seen in the epithelium of the intralobular ducts of hamsters. 20 references, 5 figures, 1 table.

Live Imaging of Calcium Dynamics during Axon Degeneration Reveals Two Functionally Distinct Phases of Calcium Influx

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Yamagishi, Yuya; Tessier-Lavigne, Marc

2015-01-01

Calcium is a key regulator of axon degeneration caused by trauma and disease, but its specific spatial and temporal dynamics in injured axons remain unclear. To clarify the function of calcium in axon degeneration, we observed calcium dynamics in single injured neurons in live zebrafish larvae and tested the temporal requirement for calcium in zebrafish neurons and cultured mouse DRG neurons. Using laser axotomy to induce Wallerian degeneration (WD) in zebrafish peripheral sensory axons, we monitored calcium dynamics from injury to fragmentation, revealing two stereotyped phases of axonal calcium influx. First, axotomy triggered a transient local calcium wave originating at the injury site. This initial calcium wave only disrupted mitochondria near the injury site and was not altered by expression of the protective WD slow (WldS) protein. Inducing multiple waves with additional axotomies did not change the kinetics of degeneration. In contrast, a second phase of calcium influx occurring minutes before fragmentation spread as a wave throughout the axon, entered mitochondria, and was abolished by WldS expression. In live zebrafish, chelating calcium after the first wave, but before the second wave, delayed the progress of fragmentation. In cultured DRG neurons, chelating calcium early in the process of WD did not alter degeneration, but chelating calcium late in WD delayed fragmentation. We propose that a terminal calcium wave is a key instructive component of the axon degeneration program. SIGNIFICANCE STATEMENT Axon degeneration resulting from trauma or neurodegenerative disease can cause devastating deficits in neural function. Understanding the molecular and cellular events that execute axon degeneration is essential for developing treatments to address these conditions. Calcium is known to contribute to axon degeneration, but its temporal requirements in this process have been unclear. Live calcium imaging in severed zebrafish neurons and temporally controlled

Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

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Patricia J Ward

Full Text Available Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2, we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2 to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555 was greater in mice that received optical treatment. Thus, the acute (1 hour, one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-. We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons.

Macrophage-independent T cell infiltration to the site of injury-induced brain inflammation

DEFF Research Database (Denmark)

Fux, Michaela; van Rooijen, Nico; Owens, Trevor

2008-01-01

We have addressed the role of macrophages in glial response and T cell entry to the CNS after axonal injury, by using intravenous injection of clodronate-loaded mannosylated liposomes, in C57BL6 mice. As expected, clodronate-liposome treatment resulted in depletion of peripheral macrophages which...... delay in the expansion of CD45(dim) CD11b(+) microglia in clodronate-liposome treated mice, but macrophage depletion had no effect on the percentage of infiltrating T cells in the lesion-reactive hippocampus. Lesion-induced TNFalpha mRNA expression was not affected by macrophage depletion, suggesting...... that activated glial cells are the primary source of this cytokine in the axonal injury-reactive brain. This identifies a potentially important distinction from inflammatory autoimmune infiltration in EAE, where macrophages are a prominent source of TNFalpha and their depletion prevents parenchymal T cell...

Bridging the gap: axonal fusion drives rapid functional recovery of the nervous system

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Jean-Sébastien Teoh

2018-01-01

Full Text Available Injuries to the central or peripheral nervous system frequently cause long-term disabilities because damaged neurons are unable to efficiently self-repair. This inherent deficiency necessitates the need for new treatment options aimed at restoring lost function to patients. Compared to humans, a number of species possess far greater regenerative capabilities, and can therefore provide important insights into how our own nervous systems can be repaired. In particular, several invertebrate species have been shown to rapidly initiate regeneration post-injury, allowing separated axon segments to re-join. This process, known as axonal fusion, represents a highly efficient repair mechanism as a regrowing axon needs to only bridge the site of damage and fuse with its separated counterpart in order to re-establish its original structure. Our recent findings in the nematode Caenorhabditis elegans have expanded the promise of axonal fusion by demonstrating that it can restore complete function to damaged neurons. Moreover, we revealed the importance of injury-induced changes in the composition of the axonal membrane for mediating axonal fusion, and discovered that the level of axonal fusion can be enhanced by promoting a neuron's intrinsic growth potential. A complete understanding of the molecular mechanisms controlling axonal fusion may permit similar approaches to be applied in a clinical setting.

Minocycline Rescues from Zinc-Induced Nigrostriatal Dopaminergic Neurodegeneration: Biochemical and Molecular Interventions.

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Kumar, Vinod; Singh, Brajesh Kumar; Chauhan, Amit Kumar; Singh, Deepali; Patel, Devendra Kumar; Singh, Chetna

2016-07-01

Accumulation of zinc (Zn) in dopaminergic neurons is implicated in Parkinson's disease (PD), and microglial activation plays a critical role in toxin-induced Parkinsonism. Oxidative stress is accused in Zn-induced dopaminergic neurodegeneration; however, its connection with microglial activation is still not known. This study was undertaken to elucidate the role and underlying mechanism of microglial activation in Zn-induced nigrostriatal dopaminergic neurodegeneration. Male Wistar rats were treated intraperitoneally with/without zinc sulphate (20 mg/kg) in the presence/absence of minocycline (30 mg/kg), a microglial activation inhibitor, for 2-12 weeks. While neurobehavioral and biochemical indexes of PD and number of dopaminergic neurons were reduced, the number of microglial cells was increased in the substantia nigra of the Zn-exposed animals. Similarly, Zn elevated lipid peroxidation (LPO) and activities of superoxide dismutase (SOD) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; however, catalase activity was reduced. Besides, Zn increased an association of NADPH oxidase subunit p67(phox) with membrane, cytochrome c release from the mitochondria and cleavage of pro-caspase 3. Zn attenuated the expression of tyrosine hydroxylase (TH) and vesicular monoamine transporter-2 (VMAT-2) while augmented the expression of dopamine transporter (DAT) and heme oxygenase-1 (HO-1). Minocycline alleviated Zn-induced behavioural impairments, loss of TH-positive neurons, activated microglial cells and biochemical indexes and modulated the expression of studied genes/proteins towards normalcy. The results demonstrate that minocycline reduces the number of activated microglial cells and oxidative stress, which rescue from Zn-induced changes in the expression of monoamine transporter and nigrostriatal dopaminergic neurodegeneration.

Regulatory Effects of Caffeic Acid Phenethyl Ester on Neuroinflammation in Microglial Cells

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Cheng-Fang Tsai

2015-03-01

Full Text Available Microglial activation has been widely demonstrated to mediate inflammatory processes that are crucial in several neurodegenerative disorders. Pharmaceuticals that can deliver direct inhibitory effects on microglia are therefore considered as a potential strategy to counter balance neurodegenerative progression. Caffeic acid phenethyl ester (CAPE, a natural phenol in honeybee propolis, is known to possess antioxidant, anti-inflammatory and anti-microbial properties. Accordingly, the current study intended to probe the effects of CAPE on microglia activation by using in vitro and in vivo models. Western blot and Griess reaction assay revealed CAPE significantly inhibited the expressions of inducible nitric oxide synthase (NOS, cyclooxygenase (COX-2 and the production of nitric oxide (NO. Administration of CAPE resulted in increased expressions of hemeoxygenase (HO-1and erythropoietin (EPO in microglia. The phosphorylated adenosine monophosphate-activated protein kinase (AMPK-α was further found to regulate the anti-inflammatory effects of caffeic acid. In vivo results from immunohistochemistry along with rotarod test also revealed the anti-neuroinflammatory effects of CAPE in microglia activation. The current study has evidenced several possible molecular determinants, AMPKα, EPO, and HO-1, in mediating anti-neuroinflammatory responses in microglial cells.

Inducible DNA-repair systems in yeast: competition for lesions.

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Mitchel, R E; Morrison, D P

1987-03-01

DNA lesions may be recognized and repaired by more than one DNA-repair process. If two repair systems with different error frequencies have overlapping lesion specificity and one or both is inducible, the resulting variable competition for the lesions can change the biological consequences of these lesions. This concept was demonstrated by observing mutation in yeast cells (Saccharomyces cerevisiae) exposed to combinations of mutagens under conditions which influenced the induction of error-free recombinational repair or error-prone repair. Total mutation frequency was reduced in a manner proportional to the dose of 60Co-gamma- or 254 nm UV radiation delivered prior to or subsequent to an MNNG exposure. Suppression was greater per unit radiation dose in cells gamma-irradiated in O2 as compared to N2. A rad3 (excision-repair) mutant gave results similar to wild-type but mutation in a rad52 (rec-) mutant exposed to MNNG was not suppressed by radiation. Protein-synthesis inhibition with heat shock or cycloheximide indicated that it was the mutation due to MNNG and not that due to radiation which had changed. These results indicate that MNNG lesions are recognized by both the recombinational repair system and the inducible error-prone system, but that gamma-radiation induction of error-free recombinational repair resulted in increased competition for the lesions, thereby reducing mutation. Similarly, gamma-radiation exposure resulted in a radiation dose-dependent reduction in mutation due to MNU, EMS, ENU and 8-MOP + UVA, but no reduction in mutation due to MMS. These results suggest that the number of mutational MMS lesions recognizable by the recombinational repair system must be very small relative to those produced by the other agents. MNNG induction of the inducible error-prone systems however, did not alter mutation frequencies due to ENU or MMS exposure but, in contrast to radiation, increased the mutagenic effectiveness of EMS. These experiments demonstrate

Polygalae Radix Extract Prevents Axonal Degeneration and Memory Deficits in a Transgenic Mouse Model of Alzheimer's Disease.

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Kuboyama, Tomoharu; Hirotsu, Keisuke; Arai, Tetsuya; Yamasaki, Hiroo; Tohda, Chihiro

2017-01-01

Memory impairments in Alzheimer's disease (AD) occur due to degenerated axons and disrupted neural networks. Since only limited recovery is possible after the destruction of neural networks, preventing axonal degeneration during the early stages of disease progression is necessary to prevent AD. Polygalae Radix (roots of Polygala tenuifolia ; PR) is a traditional herbal medicine used for sedation and amnesia. In this study, we aimed to clarify and analyze the preventive effects of PR against memory deficits in a transgenic AD mouse model, 5XFAD. 5XFAD mice demonstrated memory deficits at the age of 5 months. Thus, the water extract of Polygalae Radix (PR extract) was orally administered to 4-month-old 5XFAD mice that did not show signs of memory impairment. After consecutive administrations for 56 days, the PR extract prevented cognitive deficit and axon degeneration associated with the accumulation of amyloid β (Aβ) plaques in the perirhinal cortex of the 5XFAD mice. PR extract did not influence the formation of Aβ plaques in the brain of the 5XFAD mice. In cultured neurons, the PR extract prevented axonal growth cone collapse and axonal atrophy induced by Aβ. Additionally, it prevented Aβ-induced endocytosis at the growth cone of cultured neurons. Our previous study reported that endocytosis inhibition was enough to prevent Aβ-induced growth cone collapse, axonal degeneration, and memory impairments. Therefore, the PR extract possibly prevented axonal degeneration and memory impairment by inhibiting endocytosis. PR is the first preventive drug candidate for AD that inhibits endocytosis in neurons.

Identification of a novel dehydroergosterol enhancing microglial anti-inflammatory activity in a dairy product fermented with Penicillium candidum.

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Yasuhisa Ano

Full Text Available Despite the ever-increasing number of dementia patients worldwide, fundamental therapeutic approaches to treat this disease remain to be established. Preventive approaches such as diet, exercise and learning attract attention. Several epidemiological studies suggest that ingestion of fermented dairy products prevents cognitive decline in the elderly. These reports indicate that specific ingredients in the fermented dairy products elicit an anti-inflammatory or anti-oxidative activity that facilitates neuroprotection. The responsible components remain to be investigated. A number of studies have shown that inflammation caused by microglia is closely related to exaggeration of the pathology and cognitive decline seen in the elderly. Many researchers have proposed that controlling microglial activities could be effective in preventing and possibly curing dementia. In the present study, to elucidate specific compounds that regulate microglial activity from dairy products, repeated purification by HPLC, combined with evaluation using primary microglia, facilitated the identification of dehydroergosterol (DHE as a novel component of the extract that enhances microglial anti-inflammatory activity. DHE contains three conjugated double bonds in a steroid ring system and is an analogue of ergosterol. Despite their related chemical structures, the anti-inflammatory activity of DHE is markedly stronger than that of ergosterol. P. candidum for camembert cheese produces DHE, but P. Roqueforti for blue cheese and Aspergillus do not. DHE also induces CD11b-positive microglia cells into CD206-positive M2 type microglia. Neurotoxicity and neuronal cell death induced by excessively activated microglia is suppressed by treatment with DHE. Thus, this is the first report to demonstrate that DHE, identified as a responsible compound in dairy products, can induce microglia into a preferable phenotype for our brain environment and can be safely introduced into the body

Identification of a novel dehydroergosterol enhancing microglial anti-inflammatory activity in a dairy product fermented with Penicillium candidum.

Science.gov (United States)

Ano, Yasuhisa; Kutsukake, Toshiko; Hoshi, Ayaka; Yoshida, Aruto; Nakayama, Hiroyuki

2015-01-01

Despite the ever-increasing number of dementia patients worldwide, fundamental therapeutic approaches to treat this disease remain to be established. Preventive approaches such as diet, exercise and learning attract attention. Several epidemiological studies suggest that ingestion of fermented dairy products prevents cognitive decline in the elderly. These reports indicate that specific ingredients in the fermented dairy products elicit an anti-inflammatory or anti-oxidative activity that facilitates neuroprotection. The responsible components remain to be investigated. A number of studies have shown that inflammation caused by microglia is closely related to exaggeration of the pathology and cognitive decline seen in the elderly. Many researchers have proposed that controlling microglial activities could be effective in preventing and possibly curing dementia. In the present study, to elucidate specific compounds that regulate microglial activity from dairy products, repeated purification by HPLC, combined with evaluation using primary microglia, facilitated the identification of dehydroergosterol (DHE) as a novel component of the extract that enhances microglial anti-inflammatory activity. DHE contains three conjugated double bonds in a steroid ring system and is an analogue of ergosterol. Despite their related chemical structures, the anti-inflammatory activity of DHE is markedly stronger than that of ergosterol. P. candidum for camembert cheese produces DHE, but P. Roqueforti for blue cheese and Aspergillus do not. DHE also induces CD11b-positive microglia cells into CD206-positive M2 type microglia. Neurotoxicity and neuronal cell death induced by excessively activated microglia is suppressed by treatment with DHE. Thus, this is the first report to demonstrate that DHE, identified as a responsible compound in dairy products, can induce microglia into a preferable phenotype for our brain environment and can be safely introduced into the body by consumption of

Mouse Intermittent Hypoxia Mimicking Apnea of Prematurity: Effects on Myelinogenesis and Axonal Maturation

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CAI, JUN; TUONG, CHI MINH; ZHANG, YIPING; SHIELDS, CHRISTOPHER B.; GUO, GANG; FU, HUI; GOZAL, DAVID

2014-01-01

Premature babies are at high risk for both infantile apnea and long-term neurobehavioral deficits. Recent studies suggest that diffuse structural changes in brain white matter are a positive predictor of poor cognitive outcomes. Since oligodendrocyte maturation, myelination, axon development and synapse formation mainly occur in the 3rd trimester of gestation and 1st postnatal year, infantile apnea could lead to and/or exaggerate white matter impairments in preterm neonates. Therefore, we investigated oligodendroglia and axon development in a neonatal mouse model of intermittent hypoxia between postnatal days 2 to 10. During critical phases of central nervous system development, intermittent hypoxia induced hypomyelination in the corpus callosum, striatum, fornix and cerebellum, but not the pons or spinal cord. Intermittent hypoxia-elicited alterations in myelin-forming processes were reflected by decreased expression of myelin proteins, including MBP, PLP, MAG and CNPase, possibly due to arrested maturation of oligodendrocytes. Ultra-structural abnormalities were apparent in the myelin sheath and axon. Immature oligodendrocytes were more vulnerable to neonatal intermittent hypoxia exposures than developing axons, suggesting that hypomyelination may contribute, at least partially, to axonal deficits. Insufficient neurofilament synthesis with anomalous components of neurofilament subunits, β-tubulin and MAP2 isoforms indicated immaturity of axons in intermittent hypoxia-exposed mouse brains. In addition, down-regulation of Synapsin I, Synaptophysin and Gap-43 phosphorylation suggested a potential stunt in axonogenesis and synaptogenesis. The region-selective and complex impairment in brain white matter induced by intermittent hypoxia was further associated with electrophysiological changes that may underlie long-term neurobehavioral sequelae. PMID:21953180

LA EXTENSION DE RAMAS COLATERALES LUEGO DE UNA LESION A LA MEDULA ESPINAL ES GATILLADA POR LA DEGENERACION AXONAL Y DEPENDE DE LA EXPRESION DEL RECEPTOR DE NEUROTROFINAS P75

OpenAIRE

COLLYER SAAVEDRA, EILEEN TEHANI; COLLYER SAAVEDRA, EILEEN TEHANI

2013-01-01

Las lesiones a la médula espinal (LME) presentan un pronóstico de recuperación prácticamente nulo debido a la baja capacidad regenerativa que tiene el sistema nervioso central (SNC) de los mamíferos. Este hecho estaría determinado por factores restrictivos microambientales que impiden la regeneración y no por una incapacidad intrínseca regenerativa de las neuronas del SNC. A pesar de que los axones del SNC que han sido dañados no son capaces de regenerar, luego de una LME parcial se observ...

Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8.

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Eleanna Stamatakou

Full Text Available Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1 and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling.

A common carcinogen benzo[a]pyrene causes neuronal death in mouse via microglial activation.

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Kallol Dutta

Full Text Available BACKGROUND: Benzo[a]pyrene (B[a]P belongs to a class of polycyclic aromatic hydrocarbons that serve as micropollutants in the environment. B[a]P has been reported as a probable carcinogen in humans. Exposure to B[a]P can take place by ingestion of contaminated (especially grilled, roasted or smoked food or water, or inhalation of polluted air. There are reports available that also suggests neurotoxicity as a result of B[a]P exposure, but the exact mechanism of action is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using neuroblastoma cell line and primary cortical neuron culture, we demonstrated that B[a]P has no direct neurotoxic effect. We utilized both in vivo and in vitro systems to demonstrate that B[a]P causes microglial activation. Using microglial cell line and primary microglial culture, we showed for the first time that B[a]P administration results in elevation of reactive oxygen species within the microglia thereby causing depression of antioxidant protein levels; enhanced expression of inducible nitric oxide synthase, that results in increased production of NO from the cells. Synthesis and secretion of proinflammatory cytokines were also elevated within the microglia, possibly via the p38MAP kinase pathway. All these factors contributed to bystander death of neurons, in vitro. When administered to animals, B[a]P was found to cause microglial activation and astrogliosis in the brain with subsequent increase in proinflammatory cytokine levels. CONCLUSIONS/SIGNIFICANCE: Contrary to earlier published reports we found that B[a]P has no direct neurotoxic activity. However, it kills neurons in a bystander mechanism by activating the immune cells of the brain viz the microglia. For the first time, we have provided conclusive evidence regarding the mechanism by which the micropollutant B[a]P may actually cause damage to the central nervous system. In today's perspective, where rising pollution levels globally are a matter of grave concern, our

Conduction velocity is regulated by sodium channel inactivation in unmyelinated axons innervating the rat cranial meninges.

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De Col, Roberto; Messlinger, Karl; Carr, Richard W

2008-02-15

Axonal conduction velocity varies according to the level of preceding impulse activity. In unmyelinated axons this typically results in a slowing of conduction velocity and a parallel increase in threshold. It is currently held that Na(+)-K(+)-ATPase-dependent axonal hyperpolarization is responsible for this slowing but this has long been equivocal. We therefore examined conduction velocity changes during repetitive activation of single unmyelinated axons innervating the rat cranial meninges. In direct contradiction to the currently accepted postulate, Na(+)-K(+)-ATPase blockade actually enhanced activity-induced conduction velocity slowing, while the degree of velocity slowing was curtailed in the presence of lidocaine (10-300 microm) and carbamazepine (30-500 microm) but not tetrodotoxin (TTX, 10-80 nm). This suggests that a change in the number of available sodium channels is the most prominent factor responsible for activity-induced changes in conduction velocity in unmyelinated axons. At moderate stimulus frequencies, axonal conduction velocity is determined by an interaction between residual sodium channel inactivation following each impulse and the retrieval of channels from inactivation by a concomitant Na(+)-K(+)-ATPase-mediated hyperpolarization. Since the process is primarily dependent upon sodium channel availability, tracking conduction velocity provides a means of accessing relative changes in the excitability of nociceptive neurons.

Andrographolide Activates Keap1/Nrf2/ARE/HO-1 Pathway in HT22 Cells and Suppresses Microglial Activation by Aβ42 through Nrf2-Related Inflammatory Response.

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Seo, Ji Yeon; Pyo, Euisun; An, Jin-Pyo; Kim, Jinwoong; Sung, Sang Hyun; Oh, Won Keun

2017-01-01

Therapeutic approach of Alzheimer's disease (AD) has been gradually diversified. We examined the therapeutic and preventive potential of andrographolide, which is a lactone diterpenoid from Andrographis paniculata , and focused on the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated heme oxygenase (HO)-1-inducing effects and the inhibitory activity of amyloid beta (A β ) 42 -induced microglial activation related to Nrf2 and nuclear factor κ B (NF- κ B)-mediated inflammatory responses. Andrographolide induced the expression and translocation of Nrf2 from the cytoplasm to the nucleus, thereby activating antioxidant response element (ARE) gene transcription and HO-1 expression in murine hippocampal HT22 cells. Andrographolide eliminated intracellular A β 42 in BV-2 cells and decreased the production of interleukin (IL)-6, IL-1 β , prostaglandin (PG)E 2 , and nitric oxide (NO) because of artificial phagocytic A β 42 . It decreased pNF- κ B accumulation in the nucleus and the expression of inducible nitric oxide synthase (i-NOS) and cyclooxygenase II (COX-II) in the microglial BV-2 cell line. In summary, andrographolide activates Nrf2-mediated HO-1 expression and inhibits A β 42 -overexpressed microglial BV-2 cell activation. These results suggested that andrographolide might have the potential for further examination of the therapeutics of AD.

Andrographolide Activates Keap1/Nrf2/ARE/HO-1 Pathway in HT22 Cells and Suppresses Microglial Activation by Aβ42 through Nrf2-Related Inflammatory Response

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Ji Yeon Seo

2017-01-01

Full Text Available Therapeutic approach of Alzheimer’s disease (AD has been gradually diversified. We examined the therapeutic and preventive potential of andrographolide, which is a lactone diterpenoid from Andrographis paniculata, and focused on the Kelch-like ECH-associated protein 1 (Keap1/nuclear factor (erythroid-derived 2-like 2 (Nrf2-mediated heme oxygenase (HO-1-inducing effects and the inhibitory activity of amyloid beta (Aβ42-induced microglial activation related to Nrf2 and nuclear factor κB (NF-κB-mediated inflammatory responses. Andrographolide induced the expression and translocation of Nrf2 from the cytoplasm to the nucleus, thereby activating antioxidant response element (ARE gene transcription and HO-1 expression in murine hippocampal HT22 cells. Andrographolide eliminated intracellular Aβ42 in BV-2 cells and decreased the production of interleukin (IL-6, IL-1β, prostaglandin (PGE2, and nitric oxide (NO because of artificial phagocytic Aβ42. It decreased pNF-κB accumulation in the nucleus and the expression of inducible nitric oxide synthase (i-NOS and cyclooxygenase II (COX-II in the microglial BV-2 cell line. In summary, andrographolide activates Nrf2-mediated HO-1 expression and inhibits Aβ42-overexpressed microglial BV-2 cell activation. These results suggested that andrographolide might have the potential for further examination of the therapeutics of AD.

Signal propagation along the axon.

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Rama, Sylvain; Zbili, Mickaël; Debanne, Dominique

2018-03-08

Axons link distant brain regions and are usually considered as simple transmission cables in which reliable propagation occurs once an action potential has been generated. Safe propagation of action potentials relies on specific ion channel expression at strategic points of the axon such as nodes of Ranvier or axonal branch points. However, while action potentials are generally considered as the quantum of neuronal information, their signaling is not entirely digital. In fact, both their shape and their conduction speed have been shown to be modulated by activity, leading to regulations of synaptic latency and synaptic strength. We report here newly identified mechanisms of (1) safe spike propagation along the axon, (2) compartmentalization of action potential shape in the axon, (3) analog modulation of spike-evoked synaptic transmission and (4) alteration in conduction time after persistent regulation of axon morphology in central neurons. We discuss the contribution of these regulations in information processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

Polygalae Radix Extract Prevents Axonal Degeneration and Memory Deficits in a Transgenic Mouse Model of Alzheimer’s Disease

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Tomoharu Kuboyama

2017-11-01

Full Text Available Memory impairments in Alzheimer’s disease (AD occur due to degenerated axons and disrupted neural networks. Since only limited recovery is possible after the destruction of neural networks, preventing axonal degeneration during the early stages of disease progression is necessary to prevent AD. Polygalae Radix (roots of Polygala tenuifolia; PR is a traditional herbal medicine used for sedation and amnesia. In this study, we aimed to clarify and analyze the preventive effects of PR against memory deficits in a transgenic AD mouse model, 5XFAD. 5XFAD mice demonstrated memory deficits at the age of 5 months. Thus, the water extract of Polygalae Radix (PR extract was orally administered to 4-month-old 5XFAD mice that did not show signs of memory impairment. After consecutive administrations for 56 days, the PR extract prevented cognitive deficit and axon degeneration associated with the accumulation of amyloid β (Aβ plaques in the perirhinal cortex of the 5XFAD mice. PR extract did not influence the formation of Aβ plaques in the brain of the 5XFAD mice. In cultured neurons, the PR extract prevented axonal growth cone collapse and axonal atrophy induced by Aβ. Additionally, it prevented Aβ-induced endocytosis at the growth cone of cultured neurons. Our previous study reported that endocytosis inhibition was enough to prevent Aβ-induced growth cone collapse, axonal degeneration, and memory impairments. Therefore, the PR extract possibly prevented axonal degeneration and memory impairment by inhibiting endocytosis. PR is the first preventive drug candidate for AD that inhibits endocytosis in neurons.

HSP60 mediates the neuroprotective effects of curcumin by suppressing microglial activation.

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Ding, Feijia; Li, Fan; Li, Yunhong; Hou, Xiaolin; Ma, Yi; Zhang, Nan; Ma, Jiao; Zhang, Rui; Lang, Bing; Wang, Hongyan; Wang, Yin

2016-08-01

Curcumin has anti-inflammatory and antioxidant properties and has been widely used to treat or prevent neurodegenerative diseases. However, the mechanisms underlying the neuroprotective effects of curcumin are not well known. In the present study, the effect of curcumin on lipopolysaccharide (LPS)-stimulated BV2 mouse microglia cells was investigated using enzyme-linked immunosorbent assays of the culture medium and western blotting of cell lysates. The results showed that curcumin significantly inhibited the LPS-induced expression and release of heat shock protein 60 (HSP60) in the BV2 cells. The level of heat shock factor (HSF)-1 was upregulated in LPS-activated BV2 microglia, indicating that the increased expression of HSP60 was driven by HSF-1 activation. However, the increased HSF-1 level was downregulated by curcumin. Extracellular HSP60 is a ligand of Toll-like receptor 4 (TLR-4), and the level of the latter was increased in the LPS-activated BV2 microglia and inhibited by curcumin. The activation of TLR-4 is known to be associated with the activation of myeloid differentiation primary response 88 (MyD88) and nuclear factor (NF)-κB, with the subsequent production of proinflammatory and neurotoxic factors. In the present study, curcumin demonstrated marked suppression of the LPS-induced expression of MyD88, NF-κB, caspase-3, inducible nitric oxide synthase, tumor necrosis factor-α, interleukin (IL)-1β and IL-6 in the microglia. These results indicate that curcumin may exert its neuroprotective and anti-inflammatory effects by inhibiting microglial activation through the HSP60/TLR-4/MyD88/NF-κB signaling wpathway. Therefore, curcumin may be useful for the treatment of neurodegenerative diseases that are associated with microglial activation.

Diffuse vascular injury in fatal road traffic accident victims: its relationship to diffuse axonal injury.

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Pittella, José E H; Gusmão, Sebastião N S

2003-05-01

The authors have reported a macro- and microscopic study of brain lesions in 120 victims of fatal road traffic accidents, independent of the survival time. Diffuse vascular injury (DVI) was found in 14 patients (11.7%). All patients with DVI died within 24 h after the accident. The 14 patients with DVI also showed severe (Grade 2 or 3) diffuse axonal injury (DAI). Since DVI is restricted to road traffic accidents and incompatible with life, the high frequency observed in our series could be explained by the fact that all 120 patients were victims of road traffic accidents, and 69.2% had died within 24 h after the accident. The association between DVI and severe DAI (Grades 2 and 3) suggests that both lesions depend on the same mechanism, with the degree of axonal and vascular damage being determined by the intensity of the head acceleration. Our results show a relationship between DVI and DAI that suggest there may be a spectrum or at least a continuum between these entities as distinct from DVI being a separate entity.

System xC- is a mediator of microglial function and its deletion slows symptoms in amyotrophic lateral sclerosis mice.

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Mesci, Pinar; Zaïdi, Sakina; Lobsiger, Christian S; Millecamps, Stéphanie; Escartin, Carole; Seilhean, Danielle; Sato, Hideyo; Mallat, Michel; Boillée, Séverine

2015-01-01

Amyotrophic lateral sclerosis is the most common adult-onset motor neuron disease and evidence from mice expressing amyotrophic lateral sclerosis-causing SOD1 mutations suggest that neurodegeneration is a non-cell autonomous process where microglial cells influence disease progression. However, microglial-derived neurotoxic factors still remain largely unidentified in amyotrophic lateral sclerosis. With excitotoxicity being a major mechanism proposed to cause motor neuron death in amyotrophic lateral sclerosis, our hypothesis was that excessive glutamate release by activated microglia through their system [Formula: see text] (a cystine/glutamate antiporter with the specific subunit xCT/Slc7a11) could contribute to neurodegeneration. Here we show that xCT expression is enriched in microglia compared to total mouse spinal cord and absent from motor neurons. Activated microglia induced xCT expression and during disease, xCT levels were increased in both spinal cord and isolated microglia from mutant SOD1 amyotrophic lateral sclerosis mice. Expression of xCT was also detectable in spinal cord post-mortem tissues of patients with amyotrophic lateral sclerosis and correlated with increased inflammation. Genetic deletion of xCT in mice demonstrated that activated microglia released glutamate mainly through system [Formula: see text]. Interestingly, xCT deletion also led to decreased production of specific microglial pro-inflammatory/neurotoxic factors including nitric oxide, TNFa and IL6, whereas expression of anti-inflammatory/neuroprotective markers such as Ym1/Chil3 were increased, indicating that xCT regulates microglial functions. In amyotrophic lateral sclerosis mice, xCT deletion surprisingly led to earlier symptom onset but, importantly, this was followed by a significantly slowed progressive disease phase, which resulted in more surviving motor neurons. These results are consistent with a deleterious contribution of microglial-derived glutamate during symptomatic

[{sup 18}F]DPA-714 PET imaging of translocator protein TSPO (18 kDa) in the normal and excitotoxically-lesioned nonhuman primate brain

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Lavisse, S.; Inoue, K.; Jan, C.; Petit, F.; Dauguet, J.; Guillermier, M.; Rbah-Vidal, L.; Van Camp, N.; Aron-Badin, R.; Hantraye, P. [CEA, I2BM, MIRCen, Fontenay-aux-Roses (France); CEA, CNRS, URA2210, Fontenay-aux-Roses (France); Peyronneau, M.A.; Goutal, S.; Dolle, F. [CEA, I2BM, Service Hospitalier Frederic Joliot, Orsay (France); Remy, P. [CEA, I2BM, MIRCen, Fontenay-aux-Roses (France); CEA, CNRS, URA2210, Fontenay-aux-Roses (France); Service de Neurologie, CHU Henri Mondor, Creteil (France)

2014-12-09

We aimed to characterize pharmacologically the TSPO- radioligand [{sup 18}F]DPA-714 in the brain of healthy cynomolgus monkeys and evaluate the cellular origin of its binding in a model of neurodegeneration induced by intrastriatal injection of quinolinic acid (QA). [{sup 18}F]DPA-714 PET images were acquired before and at 2, 7, 14, 21, 49, 70, 91 days after putaminal lesioning. Blocking and displacement studies were carried out (PK11195). Different modelling approaches estimated rate constants and V{sub T} (total distribution volume) which was used to measure longitudinal changes in the lesioned putamen. Sections for immunohistochemical labelling were prepared at the same time-points to evaluate correlations between in vivo [{sup 18}F]DPA-714 binding and microglial/astrocytic activation. [{sup 18}F]DPA-714 showed a widespread distribution with a higher signal in the thalamus and occipital cortex and lower binding in the cerebellum. TSPO was expressed throughout the whole brain and about 73 % of [{sup 18}F]DPA-714 binding was specific for TSPO in vivo. The one-tissue compartment model (1-TCM) provided good and reproducible estimates of V{sub T} and rate constants, and V{sub T} values from the 1-TCM and the Logan approach were highly correlated (r {sup 2} = 0.85). QA lesioning induced an increase in V{sub T}, which was +17 %, +54 %, +157 % and +39 % higher than baseline on days 7, 14, 21 and 91 after QA injection, respectively. Immunohistochemistry revealed an early microglial and a delayed astrocytic activation after QA injection. [{sup 18}F]DPA-714 binding matched TSPO immunopositive areas and showed a stronger colocalization with CD68 microglia than with GFAP-activated astrocytes. [{sup 18}F]DPA-714 binds to TSPO with high specificity in the primate brain under normal conditions and in the QA model. This tracer provides a sensitive tool for assessing neuroinflammation in the human brain. (orig.)

Evidence for a novel chemotactic C1q domain-containing factor in the leech nerve cord.

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Tahtouh, Muriel; Croq, Françoise; Vizioli, Jacopo; Sautiere, Pierre-Eric; Van Camp, Christelle; Salzet, Michel; Daha, Mohamed R; Pestel, Joël; Lefebvre, Christophe

2009-02-01

In vertebrates, central nervous system (CNS) protection is dependent on many immune cells including microglial cells. Indeed, activated microglial cells are involved in neuroinflammation mechanisms by interacting with numerous immune factors. Unlike vertebrates, some lophotrochozoan invertebrates can fully repair their CNS following injury. In the medicinal leech Hirudo medicinalis, the recruitment of microglial cells at the lesion site is essential for sprouting of injured axons. Interestingly, a new molecule homologous to vertebrate C1q was characterized in leech, named HmC1q (for H. medicinalis) and detected in neurons and glial cells. In chemotaxis assays, leech microglial cells were demonstrated to respond to human C1q. The chemotactic activity was reduced when microglia was preincubated with signaling pathway inhibitors (Pertussis Toxin or wortmannin) or anti-human gC1qR antibody suggesting the involvement of gC1qR in C1q-mediated migration in leech. Assays using cells preincubated with NO chelator (cPTIO) showed that C1q-mediated migration was associated to NO production. Of interest, by using anti-HmC1q antibodies, HmC1q released in the culture medium was shown to exhibit a similar chemotactic effect on microglial cells as human C1q. In summary, we have identified, for the first time, a molecule homologous to mammalian C1q in leech CNS. Its chemoattractant activity on microglia highlights a new investigation field leading to better understand leech CNS repair mechanisms.

Craniocerebral trauma. Magnetic resonance imaging of diffuse axonal injury

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Mallouhi, A.

2014-01-01

Acceleration-deceleration rotational brain trauma is a common cause of disability or death in young adults and often leads to a focal destruction of axons. The resulting pathology, axonal shear injury is referred to as diffuse axonal injury (DAI). The DAI-associated lesions occur bilaterally, are widely dispersed and have been observed in the surface and deep white matter. They are found near to and far from the impact site. When DAI is clinically suspected, magnetic resonance imaging (MRI) is the method of choice for further clarification, especially in patients where cranial computed tomography (CT) is inconspicuous. To investigate the presence of DAI after traumatic brain injury (TBI), a multimodal MRI approach is applied including the common structural and also functional imaging sequences. For structural MRI, fluid-attenuated inversion recovery (FLAIR) weighted and susceptibility contrast imaging (SWI) are the sequences mainly used. The SWI technique is extremely sensitive to blood breakdown products, which appear as small signal voids at three locations, at the gray-white interface, in the corpus callosum and in the brain stem. Functional MRI comprises a group of constantly developing techniques that have great potential in optimal evaluation of the white matter in patients after craniocerebral trauma. These imaging techniques allow the visualization of changes associated with shear injuries, such as functional impairment of axons and decreased blood flow and abnormal metabolic activity of the brain parts affected. The multimodal MRI approach in patients with DAI results in a more detailed and differentiated representation of the underlying pathophysiological changes of the injured nerve tracts and helps to improve the diagnostic and prognostic accuracy of MRI. When DAI is suspected multimodal MRI should be performed as soon as possible after craniocerebral injury. (orig.) [de

Axons take a dive

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Tong, Cheuk Ka; Cebrián-Silla, Arantxa; Paredes, Mercedes F; Huang, Eric J; García-Verdugo, Jose Manuel; Alvarez-Buylla, Arturo

2015-01-01

In the walls of the lateral ventricles of the adult mammalian brain, neural stem cells (NSCs) and ependymal (E1) cells share the apical surface of the ventricular–subventricular zone (V–SVZ). In a recent article, we show that supraependymal serotonergic (5HT) axons originating from the raphe nuclei in mice form an extensive plexus on the walls of the lateral ventricles where they contact E1 cells and NSCs. Here we further characterize the contacts between 5HT supraependymal axons and E1 cells in mice, and show that suprependymal axons tightly associated to E1 cells are also present in the walls of the human lateral ventricles. These observations raise interesting questions about the function of supraependymal axons in the regulation of E1 cells. PMID:26413556

Microglial dystrophy in the aged and Alzheimer's disease brain is associated with ferritin immunoreactivity.

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Lopes, Kryslaine O; Sparks, D Larry; Streit, Wolfgang J

2008-08-01

Degeneration of microglial cells may be important for understanding the pathogenesis of aging-related neurodegeneration and neurodegenerative diseases. In this study, we analyzed the morphological characteristics of microglial cells in the nondemented and Alzheimer's disease (AD) human brain using ferritin immunohistochemistry. The central hypothesis was that expression of the iron storage protein ferritin increases the susceptibility of microglia to degeneration, particularly in the aged brain since senescent microglia might become less efficient in maintaining iron homeostasis and free iron can promote oxidative damage. In a primary set of 24 subjects (age range 34-97 years) examined, microglial cells immunoreactive for ferritin were found to constitute a subpopulation of the larger microglial pool labeled with an antibody for HLA-DR antigens. The majority of these ferritin-positive microglia exhibited aberrant morphological (dystrophic) changes in the aged and particularly in the AD brain. No spatial correlation was found between ferritin-positive dystrophic microglia and senile plaques in AD tissues. Analysis of a secondary set of human postmortem brain tissues with a wide range of postmortem intervals (PMI, average 10.94 +/- 5.69 h) showed that the occurrence of microglial dystrophy was independent of PMI and consequently not a product of tissue autolysis. Collectively, these results suggest that microglial involvement in iron storage and metabolism contributes to their degeneration, possibly through increased exposure of the cells to oxidative stress. We conclude that ferritin immunohistochemistry may be a useful method for detecting degenerating microglia in the human brain. (c) 2008 Wiley-Liss, Inc.

Establishment of mouse neuron and microglial cell co-cultured models and its action mechanism.

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Zhang, Bo; Yang, Yunfeng; Tang, Jun; Tao, Yihao; Jiang, Bing; Chen, Zhi; Feng, Hua; Yang, Liming; Zhu, Gang

2017-06-27

The objective of this study is to establish a co-culture model of mouse neurons and microglial cells, and to analyze the mechanism of action of oxygen glucose deprivation (OGD) and transient oxygen glucose deprivation (tOGD) preconditioning cell models. Mouse primary neurons and BV2 microglial cells were successfully cultured, and the OGD and tOGD models were also established. In the co-culture of mouse primary neurons and microglial cells, the cell number of tOGD mouse neurons and microglial cells was larger than the OGD cell number, observed by a microscope. CCK-8 assay result showed that at 1h after treatment, the OD value in the control group is lower compared to all the other three groups (P control group compared to other three groups (P neurons cells were cultured. In the meantime mouse BV2 microglia cells were cultured. Two types of cells were co-cultured, and OGD and tOGD cell models were established. There were four groups in the experiment: control group (OGD), treatment group (tOGD+OGD), placebo group (tOGD+OGD+saline) and minocycline intervention group (tOGD+OGD+minocycline). CCK-8 kit was used to detect cell viability and flow cytometry was used to detect apoptosis. In this study, mouse primary neurons and microglial cells were co-cultured. The OGD and tOGD models were established successfully. tOGD was able to effectively protect neurons and microglial cells from damage, and inhibit the apoptosis caused by oxygen glucose deprivation.

Regional Retinal Ganglion Cell Axon Loss in a Murine Glaucoma Model.

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Schaub, Julie A; Kimball, Elizabeth C; Steinhart, Matthew R; Nguyen, Cathy; Pease, Mary E; Oglesby, Ericka N; Jefferys, Joan L; Quigley, Harry A

2017-05-01

To determine if retinal ganglion cell (RGC) axon loss in experimental mouse glaucoma is uniform in the optic nerve. Experimental glaucoma was induced for 6 weeks with a microbead injection model in CD1 (n = 78) and C57BL/6 (B6, n = 68) mice. From epoxy-embedded sections of optic nerve 1 to 2 mm posterior to the globe, total nerve area and regional axon density (axons/1600 μm2) were measured in superior, inferior, nasal, and temporal zones. Control eyes of CD1 mice have higher axon density and more total RGCs than control B6 mice eyes. There were no significant differences in control regional axon density in all mice or by strain (all P > 0.2, mixed model). Exposure to elevated IOP caused loss of RGC in both strains. In CD1 mice, axon density declined without significant loss of nerve area, while B6 mice had less density loss, but greater decrease in nerve area. Axon density loss in glaucoma eyes was not significantly greater in any region in either mouse strain (both P > 0.2, mixed model). In moderately damaged CD1 glaucoma eyes, and CD1 eyes with the greatest IOP elevation exposure, density loss differed by region (P = 0.05, P = 0.03, mixed model) with the greatest loss in the temporal and superior regions, while in severely injured B6 nerves superior loss was greater than inferior loss (P = 0.01, mixed model, Bonferroni corrected). There was selectively greater loss of superior and temporal optic nerve axons of RGCs in mouse glaucoma at certain stages of damage. Differences in nerve area change suggest non-RGC responses differ between mouse strains.

Axonal regeneration in zebrafish spinal cord

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Hui, Subhra Prakash

2018-01-01

Abstract In the present review we discuss two interrelated events—axonal damage and repair—known to occur after spinal cord injury (SCI) in the zebrafish. Adult zebrafish are capable of regenerating axonal tracts and can restore full functionality after SCI. Unlike fish, axon regeneration in the adult mammalian central nervous system is extremely limited. As a consequence of an injury there is very little repair of disengaged axons and therefore functional deficit persists after SCI in adult mammals. In contrast, peripheral nervous system axons readily regenerate following injury and hence allow functional recovery both in mammals and fish. A better mechanistic understanding of these three scenarios could provide a more comprehensive insight into the success or failure of axonal regeneration after SCI. This review summarizes the present understanding of the cellular and molecular basis of axonal regeneration, in both the peripheral nervous system and the central nervous system, and large scale gene expression analysis is used to focus on different events during regeneration. The discovery and identification of genes involved in zebrafish spinal cord regeneration and subsequent functional experimentation will provide more insight into the endogenous mechanism of myelination and remyelination. Furthermore, precise knowledge of the mechanism underlying the extraordinary axonal regeneration process in zebrafish will also allow us to unravel the potential therapeutic strategies to be implemented for enhancing regrowth and remyelination of axons in mammals. PMID:29721326

Comprehensive Evaluation of Neuroprotection Achieved by Extended Selective Brain Cooling Therapy in a Rat Model of Penetrating Ballistic-Like Brain Injury

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Shear, Deborah A.; Deng-Bryant, Ying; Leung, Lai Yee; Wei, Guo; Chen, Zhiyong; Tortella, Frank C.

2016-01-01

Brain hypothermia has been considered as a promising alternative to whole-body hypothermia in treating acute neurological disease, for example, traumatic brain injury. Previously, we demonstrated that 2-hours selective brain cooling (SBC) effectively mitigated acute (≤24 hours postinjury) neurophysiological dysfunction induced by a penetrating ballistic-like brain injury (PBBI) in rats. This study evaluated neuroprotective effects of extended SBC (4 or 8 hours in duration) on sub-acute secondary injuries between 3 and 21 days postinjury (DPI). SBC (34°C) was achieved via extraluminal cooling of rats' bilateral common carotid arteries (CCA). Depending on the experimental design, SBC was introduced either immediately or with a 2- or 4-hour delay after PBBI and maintained for 4 or 8 hours. Neuroprotective effects of SBC were evaluated by measuring brain lesion volume, axonal injury, neuroinflammation, motor and cognitive functions, and post-traumatic seizures. Compared to untreated PBBI animals, 4 or 8 hours SBC treatment initiated immediately following PBBI produced comparable neuroprotective benefits against PBBI-induced early histopathology at 3 DPI as evidenced by significant reductions in brain lesion volume, axonal pathology (beta-amyloid precursor protein staining), neuroinflammation (glial fibrillary acetic protein stained-activated astrocytes and rat major histocompatibility complex class I stained activated microglial cell), and post-traumatic nonconvulsive seizures. In the later phase of the injury (7–21 DPI), significant improvement on motor function (rotarod test) was observed under most SBC protocols, including the 2-hour delay in SBC initiation. However, SBC treatment failed to improve cognitive performance (Morris water maze test) measured 13–17 DPI. The protective effects of SBC on delayed axonal injury (silver staining) were evident out to 14 DPI. In conclusion, the CCA cooling method of SBC produced neuroprotection measured across multiple

Meninges-derived cues control axon guidance.

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Suter, Tracey A C S; DeLoughery, Zachary J; Jaworski, Alexander

2017-10-01

The axons of developing neurons travel long distances along stereotyped pathways under the direction of extracellular cues sensed by the axonal growth cone. Guidance cues are either secreted proteins that diffuse freely or bind the extracellular matrix, or membrane-anchored proteins. Different populations of axons express distinct sets of receptors for guidance cues, which results in differential responses to specific ligands. The full repertoire of axon guidance cues and receptors and the identity of the tissues producing these cues remain to be elucidated. The meninges are connective tissue layers enveloping the vertebrate brain and spinal cord that serve to protect the central nervous system (CNS). The meninges also instruct nervous system development by regulating the generation and migration of neural progenitors, but it has not been determined whether they help guide axons to their targets. Here, we investigate a possible role for the meninges in neuronal wiring. Using mouse neural tissue explants, we show that developing spinal cord meninges produce secreted attractive and repulsive cues that can guide multiple types of axons in vitro. We find that motor and sensory neurons, which project axons across the CNS-peripheral nervous system (PNS) boundary, are attracted by meninges. Conversely, axons of both ipsi- and contralaterally projecting dorsal spinal cord interneurons are repelled by meninges. The responses of these axonal populations to the meninges are consistent with their trajectories relative to meninges in vivo, suggesting that meningeal guidance factors contribute to nervous system wiring and control which axons are able to traverse the CNS-PNS boundary. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental Demyelination and Axonal Loss Are Reduced in MicroRNA-146a Deficient Mice.

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Martin, Nellie A; Molnar, Viktor; Szilagyi, Gabor T; Elkjaer, Maria L; Nawrocki, Arkadiusz; Okarmus, Justyna; Wlodarczyk, Agnieszka; Thygesen, Eva K; Palkovits, Miklos; Gallyas, Ferenc; Larsen, Martin R; Lassmann, Hans; Benedikz, Eirikur; Owens, Trevor; Svenningsen, Asa F; Illes, Zsolt

2018-01-01

The cuprizone (CPZ) model of multiple sclerosis (MS) was used to identify microRNAs (miRNAs) related to in vivo de- and remyelination. We further investigated the role of miR-146a in miR-146a-deficient (KO) mice: this miRNA is differentially expressed in MS lesions and promotes differentiation of oligodendrocyte precursor cells (OPCs) during remyelination, but its role has not been examined during demyelination. MicroRNAs were examined by Agilent Mouse miRNA Microarray in the corpus callosum during CPZ-induced demyelination and remyelination. Demyelination, axonal loss, changes in number of oligodendrocytes, OPCs, and macrophages/microglia was compared by histology/immunohistochemistry between KO and WT mice. Differential expression of target genes and proteins of miR-146a was analyzed in the transcriptome (4 × 44K Agilent Whole Mouse Genome Microarray) and proteome (liquid chromatography tandem mass spectrometry) of CPZ-induced de- and remyelination in WT mice. Levels of proinflammatory molecules in the corpus callosum were compared in WT versus KO mice by Meso Scale Discovery multiplex protein analysis. miR-146a was increasingly upregulated during CPZ-induced de- and remyelination. The absence of miR-146a in KO mice protected against demyelination, axonal loss, body weight loss, and atrophy of thymus and spleen. The number of CNP + oligodendrocytes was increased during demyelination in the miR-146a KO mice, while there was a trend of increased number of NG2 + OPCs in the WT mice. miR-146a target genes, SNAP25 and SMAD4, were downregulated in the proteome of demyelinating corpus callosum in WT mice. Higher levels of SNAP25 were measured by ELISA in the corpus callosum of miR-146a KO mice, but there was no difference between KO and WT mice during demyelination. Multiplex protein analysis of the corpus callosum lysate revealed upregulated TNF-RI, TNF-RII, and CCL2 in the WT mice in contrast to KO mice. The number of Mac3 + and Iba1 + macrophages/microglia was

Zinc is released by cultured astrocytes as a gliotransmitter under hypoosmotic stress-loaded conditions and regulates microglial activity.

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Segawa, Shohei; Nishiura, Takeshi; Furuta, Takahiro; Ohsato, Yuki; Tani, Misaki; Nishida, Kentaro; Nagasawa, Kazuki

2014-01-17

Astrocytes contribute to the maintenance of brain homeostasis via the release of gliotransmitters such as ATP and glutamate. Here we examined whether zinc was released from astrocytes under stress-loaded conditions, and was involved in the regulation of microglial activity as a gliotransmitter. Hypoosmotic stress was loaded to astrocytes using balanced salt solution prepared to 214-314 mOsmol/L, and then intra- and extra-cellular zinc levels were assessed using Newport Green DCF diacetate (NG) and ICP-MS, respectively. Microglial activation by the astrocytic supernatant was assessed by their morphological changes and poly(ADP-ribose) (PAR) polymer accumulation. Exposure of astrocytes to hypoosmotic buffer, increased the extracellular ATP level in osmolarity-dependent manners, indicating a load of hypoosmotic stress. In hypoosmotic stress-loaded astrocytes, there were apparent increases in the intra- and extra-cellular zinc levels. Incubation of microglia in the astrocytic conditioned medium transformed them into the activated "amoeboid" form and induced PAR formation. Administration of an extracellular zinc chelator, CaEDTA, to the astrocytic conditioned medium almost completely prevented the microglial activation. Treatment of astrocytes with an intracellular zinc chelator, TPEN, suppressed the hypoosmotic stress-increased intracellular, but not the extracellular, zinc level, and the increase in the intracellular zinc level was blocked partially by a nitric oxide synthase inhibitor, but not by CaEDTA, indicating that the mechanisms underlying the increases in the intra- and extra-cellular zinc levels might be different. These findings suggest that under hypoosmotic stress-loaded conditions, zinc is released from astrocytes and then plays a primary role in microglial activation as a gliotransmitter. Copyright © 2013 Elsevier Inc. All rights reserved.

RGM is a repulsive guidance molecule for retinal axons

DEFF Research Database (Denmark)

Monnier, Philippe P; Sierra, Ana; Macchi, Paolo

2002-01-01

with known guidance cues, and its messenger RNA is distributed in a gradient with increasing concentration from the anterior to posterior pole of the embryonic tectum. Recombinant RGM at low nanomolar concentration induces collapse of temporal but not of nasal growth cones and guides temporal retinal axons...

Immortalized sheep microglial cells are permissive to a diverse range of ruminant viruses.

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Stanton, James B; Swanson, Beryl; Orozco, Edith; Muñoz-Gutiérrez, Juan F; Evermann, James F; Ridpath, Julia F

2017-12-01

Ruminants, including sheep and goats (small ruminants), are key agricultural animals in many parts of the world. Infectious diseases, including many viral diseases, are significant problems to efficient production of ruminants. Unfortunately, reagents tailored to viruses of ruminants, and especially small ruminants, are lacking compared to other animals more typically used for biomedical research. The purpose of this study was to determine the permissibility of a stably immortalized, sheep microglial cell line to viruses that are reported to infect ruminants: bovine viral diarrhea virus (BVDV), bovine herpesvirus 1 (BoHV-1), small ruminant lentiviruses (SRLV), and bovine respiratory syncytial virus (BRSV). Sublines A and H of previously isolated, immortalized, and characterized (CD14-positive) ovine microglial cells were used. Bovine turbinate cells and goat synovial membrane cells were used for comparison. Cytopathic changes were used to confirm infection of individual wells, which were then counted and used to calculate the 50% tissue culture infectious dose. Uninoculated cells served as negative controls and confirmed that the cells were not previously infected with these viruses using polymerase chain reaction (PCR). Inoculation of the two microglial cell sublines with laboratory and field isolates of BVDV, BoHV-1, and BRSV resulted in viral infection in a manner similar to bovine turbinate cells. Immortalized microglia cells are also permissive to SRLV, similar to goat synovial membrane cells. These immortalized sheep microglial cells provide a new tool for the study of ruminant viruses in ruminant microglial cell line.

Microglial-derived miRNA let-7 and HMGB1 contribute to ethanol-induced neurotoxicity via TLR7.

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Coleman, Leon G; Zou, Jian; Crews, Fulton T

2017-01-25

Toll-like receptor (TLR) signaling is emerging as an important component of neurodegeneration. TLR7 senses viral RNA and certain endogenous miRNAs to initiate innate immune responses leading to neurodegeneration. Alcoholism is associated with hippocampal degeneration, with preclinical studies linking ethanol-induced neurodegeneration with central innate immune induction and TLR activation. The endogenous miRNA let-7b binds TLR7 to cause neurodegeneration. TLR7 and other immune markers were assessed in postmortem human hippocampal tissue that was obtained from the New South Wales Tissue Bank. Rat hippocampal-entorhinal cortex (HEC) slice culture was used to assess specific effects of ethanol on TLR7, let-7b, and microvesicles. We report here that hippocampal tissue from postmortem human alcoholic brains shows increased expression of TLR7 and increased microglial activation. Using HEC slice culture, we found that ethanol induces TLR7 and let-7b expression. Ethanol caused TLR7-associated neuroimmune gene induction and initiated the release let-7b in microvesicles (MVs), enhancing TLR7-mediated neurotoxicity. Further, ethanol increased let-7b binding to the danger signaling molecule high mobility group box-1 (HMGB1) in MVs, while reducing let-7 binding to classical chaperone protein argonaute (Ago2). Flow cytometric analysis of MVs from HEC media and analysis of MVs from brain cell culture lines found that microglia were the primary source of let-7b and HMGB1-containing MVs. Our results identify that ethanol induces neuroimmune pathology involving the release of let-7b/HMGB1 complexes in microglia-derived microvesicles. This contributes to hippocampal neurodegeneration and may play a role in the pathology of alcoholism.

Acute alcohol intoxication, diffuse axonal injury and intraventricular bleeding in patients with isolated blunt traumatic brain injury.

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Matsukawa, Hidetoshi; Shinoda, Masaki; Fujii, Motoharu; Takahashi, Osamu; Murakata, Atsushi; Yamamoto, Daisuke

2013-01-01

The influence of blood alcohol level (BAL) on outcome remains unclear. This study investigated the relationships between BAL, type and number of diffuse axonal injury (DAI), intraventricular bleeding (IVB) and 6-month outcome. This study reviewed 419 patients with isolated blunt traumatic brain injury. First, it compared clinical and radiological characteristics between patients with good recovery and disability. Second, it compared BAL among DAI lesions. Third, it evaluated the correlation between the BAL and severity of IVB, number of DAI and corpus callosum injury lesions. Regardless of BAL, older age, male gender, severe Glasgow Coma Scale score (injury lesions. Acute alcohol intoxication was not associated with type and number of DAI lesion, IVB and disability. This study suggested that a specific type of traumatic lesion, specifically lesion on genu of corpus callosum and IVB, might be more vital for outcome.

TMEM16F Regulates Spinal Microglial Function in Neuropathic Pain States

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Laura Batti

2016-06-01

Full Text Available Neuropathic pain is a widespread chronic pain state that results from injury to the nervous system. Spinal microglia play a causative role in the pathogenesis of neuropathic pain through secretion of growth factors and cytokines. Here, we investigated the contribution of TMEM16F, a protein that functions as a Ca2+-dependent ion channel and a phospholipid scramblase, to microglial activity during neuropathic pain. We demonstrate that mice with a conditional ablation of TMEM16F in microglia do not develop mechanical hypersensitivity upon nerve injury. In the absence of TMEM16F, microglia display deficits in process motility and phagocytosis. Moreover, loss of GABA immunoreactivity upon injury is spared in TMEM16F conditional knockout mice. Collectively, these data indicate that TMEM16F is an essential component of the microglial response to injury and suggest the importance of microglial phagocytosis in the pathogenesis of neuropathic pain.

Direct transfer of viral and cellular proteins from varicella-zoster virus-infected non-neuronal cells to human axons.

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Grigoryan, Sergei; Yee, Michael B; Glick, Yair; Gerber, Doron; Kepten, Eldad; Garini, Yuval; Yang, In Hong; Kinchington, Paul R; Goldstein, Ronald S

2015-01-01

Varicella Zoster Virus (VZV), the alphaherpesvirus that causes varicella upon primary infection and Herpes zoster (shingles) following reactivation in latently infected neurons, is known to be fusogenic. It forms polynuclear syncytia in culture, in varicella skin lesions and in infected fetal human ganglia xenografted to mice. After axonal infection using VZV expressing green fluorescent protein (GFP) in compartmentalized microfluidic cultures there is diffuse filling of axons with GFP as well as punctate fluorescence corresponding to capsids. Use of viruses with fluorescent fusions to VZV proteins reveals that both proteins encoded by VZV genes and those of the infecting cell are transferred in bulk from infecting non-neuronal cells to axons. Similar transfer of protein to axons was observed following cell associated HSV1 infection. Fluorescence recovery after photobleaching (FRAP) experiments provide evidence that this transfer is by diffusion of proteins from the infecting cells into axons. Time-lapse movies and immunocytochemical experiments in co-cultures demonstrate that non-neuronal cells fuse with neuronal somata and proteins from both cell types are present in the syncytia formed. The fusogenic nature of VZV therefore may enable not only conventional entry of virions and capsids into axonal endings in the skin by classical entry mechanisms, but also by cytoplasmic fusion that permits viral protein transfer to neurons in bulk.

Mecanismos involucrados en la promoción de crecimiento axonal por la glia envolvente del bulbo olfatorio

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Vilma C. Muñetón-Gómez

2001-06-01

Full Text Available La actividad que promueve el crecimiento de axones por la glia envolvente (GE del bulbo olfatorio depende de la expresión de diversas moléculas durante el desarrollo, la vida adulta y la reparación de lesiones nerviosas. Diversas moléculas tales como las neurotrofinas y sus receptores, los factores de crecimiento, las moléculas de adhesión celular, las moléculas de matriz extracelular y las moléculas asociadas con la mielinización son producidas por la glia del sistema olfatorio durante el desarrollo. Su expresión sostenida durante la vida adulta parece estar asociada con el reemplazo celular y la alta plasticidad de este sistema. A su vez, su expresión se involucra en procesos de reparación de lesiones mediados por trasplantes de glia. La migración de la GE, que acompaña axones en crecimiento, se observa durante el desarrollo y en procesos de regeneración luego de una lesión. Los trasplantes de,GE permiten la navegación de brotes regenerantes a través del tejido gliótico inhibidor formado luego de una lesión del sistema nervioso central. El propósito de esta revisión es profundizar en los mecanismos de actividad promotora de crecimiento axonal.

Genetic ablation of soluble TNF does not affect lesion size and functional recovery after moderate spinal cord injury in mice

DEFF Research Database (Denmark)

Ellman, Ditte Gry; Degn, Matilda; Lund, Minna Christiansen

2016-01-01

Traumatic spinal cord injury (SCI) is followed by an instant increase in expression of the microglial-derived proinflammatory cytokine tumor necrosis factor (TNF) within the lesioned cord. TNF exists both as membrane-anchored TNF (mTNF) and as cleaved soluble TNF (solTNF). We previously demonstra......, and MHCII), lesion size, and functional outcome after moderate SCI were comparable between genotypes. Collectively, our data demonstrate that genetic ablation of solTNF does not significantly modulate postlesion outcome after SCI....

Microglial cell dysregulation in Brain Aging and Neurodegeneration.

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Rommy eVon Bernhardi

2015-07-01

Full Text Available Aging is the main risk factor for neurodegenerative diseases. In aging, microglia undergo phenotypic changes compatible with their activation. Glial activation can lead to neuroinflammation, which is increasingly accepted as part of the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD. We hypothesize that in aging, aberrant microglia activation leads to a deleterious environment and neurodegeneration. In aged mice, microglia exhibit an increased expression of cytokines and an exacerbated inflammatory response to pathological changes. Whereas LPS increases nitric oxide secretion in microglia from young mice, induction of reactive oxygen species (ROS predominates in older mice. Furthermore, there is accumulation of DNA oxidative damage in mitochondria of microglia during aging, and also an increased intracellular ROS production. Increased ROS activates the redox-sensitive nuclear factor kappa B, which promotes more neuroinflammation, and can be translated in functional deficits, such as cognitive impairment. Mitochondria-derived ROS and cathepsin B, are also necessary for the microglial cell production of interleukin-1β, a key inflammatory cytokine. Interestingly, whereas the regulatory cytokine TGFβ1 is also increased in the aged brain, neuroinflammation persists. Assessing this apparent contradiction, we have reported that TGFβ1 induction and activation of Smad3 signaling after inflammatory stimulation are reduced in adult mice. Other protective functions, such as phagocytosis, although observed in aged animals, become not inducible by inflammatory stimuli and TGFβ1. Here, we discuss data suggesting that mitochondrial and endolysosomal dysfunction could at least partially mediate age-associated microglial cell changes, and, together with the impairment of the TGFβ1-Smad3 pathway, could result in a reduction of protective activation and a facilitation of cytotoxic activation of microglia, resulting in the

Radiation-induced vascular lesions of the skin: an overview

NARCIS (Netherlands)

Flucke, U.E.; Requena, L.; Mentzel, T.

2013-01-01

Radiation-induced cutaneous vascular neoplasms occur infrequently and comprise benign, so-called atypical vascular lesions (AVL) and angiosarcomas (AS), often being high-grade malignant tumors. Both arise most frequently within previously irradiated skin in breast-conserving-treated mammary cancer

Axonal Control of the Adult Neural Stem Cell Niche

Science.gov (United States)

Tong, Cheuk Ka; Chen, Jiadong; Cebrián-Silla, Arantxa; Mirzadeh, Zaman; Obernier, Kirsten; Guinto, Cristina D.; Tecott, Laurence H.; García-Verdugo, Jose Manuel; Kriegstein, Arnold; Alvarez-Buylla, Arturo

2014-01-01

SUMMARY The ventricular-subventricular zone (V-SVZ) is an extensive germinal niche containing neural stem cells (NSC) in the walls of the lateral ventricles of the adult brain. How the adult brain’s neural activity influences the behavior of adult NSCs remains largely unknown. We show that serotonergic (5HT) axons originating from a small group of neurons in the raphe form an extensive plexus on most of the ventricular walls. Electron microscopy revealed intimate contacts between 5HT axons and NSCs (B1) or ependymal cells (E1) and these cells were labeled by a transsynaptic viral tracer injected into the raphe. B1 cells express the 5HT receptors 2C and 5A. Electrophysiology showed that activation of these receptors in B1 cells induced small inward currents. Intraventricular infusion of 5HT2C agonist or antagonist increased or decreased V-SVZ proliferation, respectively. These results indicate that supraependymal 5HT axons directly interact with NSCs to regulate neurogenesis via 5HT2C. PMID:24561083

X-irradiation-induced nuclear lesions in cultured mammaliam cells: an ultrastructural analysis

International Nuclear Information System (INIS)

Barham, S.S.; Walters, R.A.

1978-01-01

Electron-dense chromatin aggregates, hereafter referred to as lesions, have been characterized morphologically within interphase nuclei of Chinese hamster cells (line CHO) after a single acute exposure to 400, 800, 1200, or 2000 rad of x irradiation. At all doses studied, lesions were observed only after termination of radiation-induced division delay. Cell profiles were scored by electron microscopy for the presence or absence of nuclear lesions at various times after irradiation. The mitotic fraction from each irradiated population was also scored for each sample by light and electron microscopy. From these data and from simultaneous cell-density counts for each sample, it is apparent that postirradiation cell division is a prerequisite to formation of interphase nuclear lesions. Irradiated cell populations blocked in mitosis by Colcemid beyond the normal period of postirradiation division-delay failed to display nuclear lesions until after Colcemid was removed and cell division was completed. Enzyme digestions of isolated nuclei from irradiated cells with DNase I, RNase A, and Pronase suggest that the nuclear lesions are comprised primarily of chromatin. Nucleolar lesions, as well as various aberrant morphological forms of nucleoli, were also observed in cell populations after the onset of postirradiation cell division during the first 72 hr following exposure to irradiation. Delayed radiation-induced ultrastructural alterations of the nucleus included the formation of cytoplasmic invaginations into the nuclear space and inclusions of membranes within nuclei

Acute nutritional axonal neuropathy.

Science.gov (United States)

Hamel, Johanna; Logigian, Eric L

2018-01-01

This study describes clinical, laboratory, and electrodiagnostic features of a severe acute axonal polyneuropathy common to patients with acute nutritional deficiency in the setting of alcoholism, bariatric surgery (BS), or anorexia. Retrospective analysis of clinical, electrodiagnostic, and laboratory data of patients with acute axonal neuropathy. Thirteen patients were identified with a severe, painful, sensory or sensorimotor axonal polyneuropathy that developed over 2-12 weeks with sensory ataxia, areflexia, variable muscle weakness, poor nutritional status, and weight loss, often with prolonged vomiting and normal cerebrospinal fluid protein. Vitamin B6 was low in half and thiamine was low in all patients when obtained before supplementation. Patients improved with weight gain and vitamin supplementation, with motor greater than sensory recovery. We suggest that acute or subacute axonal neuropathy in patients with weight loss or vomiting associated with alcohol abuse, BS, or dietary deficiency is one syndrome, caused by micronutrient deficiencies. Muscle Nerve 57: 33-39, 2018. © 2017 Wiley Periodicals, Inc.

A novel ALS-associated variant in UBQLN4 regulates motor axon morphogenesis

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Edens, Brittany M; Yan, Jianhua; Miller, Nimrod; Deng, Han-Xiang; Siddique, Teepu; Ma, Yongchao C

2017-01-01

The etiological underpinnings of amyotrophic lateral sclerosis (ALS) are complex and incompletely understood, although contributions to pathogenesis by regulators of proteolytic pathways have become increasingly apparent. Here, we present a novel variant in UBQLN4 that is associated with ALS and show that its expression compromises motor axon morphogenesis in mouse motor neurons and in zebrafish. We further demonstrate that the ALS-associated UBQLN4 variant impairs proteasomal function, and identify the Wnt signaling pathway effector beta-catenin as a UBQLN4 substrate. Inhibition of beta-catenin function rescues the UBQLN4 variant-induced motor axon phenotypes. These findings provide a strong link between the regulation of axonal morphogenesis and a new ALS-associated gene variant mediated by protein degradation pathways. DOI: http://dx.doi.org/10.7554/eLife.25453.001 PMID:28463112

Axonal transport and secretion of fibrillar forms of α-synuclein, Aβ42 peptide and HTTExon 1.

Science.gov (United States)

Brahic, Michel; Bousset, Luc; Bieri, Gregor; Melki, Ronald; Gitler, Aaron D

2016-04-01

Accruing evidence suggests that prion-like behavior of fibrillar forms of α-synuclein, β-amyloid peptide and mutant huntingtin are responsible for the spread of the lesions that characterize Parkinson disease, Alzheimer disease and Huntington disease, respectively. It is unknown whether these distinct protein assemblies are transported within and between neurons by similar or distinct mechanisms. It is also unclear if neuronal death or injury is required for neuron-to-neuron transfer. To address these questions, we used mouse primary cortical neurons grown in microfluidic devices to measure the amounts of α-synuclein, Aβ42 and HTTExon1 fibrils transported by axons in both directions (anterograde and retrograde), as well as to examine the mechanism of their release from axons after anterograde transport. We observed that the three fibrils were transported in both anterograde and retrograde directions but with strikingly different efficiencies. The amount of Aβ42 fibrils transported was ten times higher than that of the other two fibrils. HTTExon1 was efficiently transported in the retrograde direction but only marginally in the anterograde direction. Finally, using neurons from two distinct mutant mouse strains whose axons are highly resistant to neurodegeneration (Wld(S) and Sarm1(-/-)), we found that the three different fibrils were secreted by axons after anterograde transport, in the absence of axonal lysis, indicating that trans-neuronal spread can occur in intact healthy neurons. In summary, fibrils of α-synuclein, Aβ42 and HTTExon1 are all transported in axons but in directions and amounts that are specific of each fibril. After anterograde transport, the three fibrils were secreted in the medium in the absence of axon lysis. Continuous secretion could play an important role in the spread of pathology between neurons but may be amenable to pharmacological intervention.

The discovery of the growth cone and its influence on the study of axon guidance

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Elisa eTamariz

2015-05-01

Full Text Available For over a century, there has been a great deal of interest in understanding how neural connectivity is established during development and regeneration. Interest in the latter arises from the possibility that knowledge of this process can be used to reestablish lost connections after lesion or neurodegeneration. At the end of the XIX century, Santiago Ramón y Cajal discovered that the distal tip of growing axons contained a structure that he called the growth cone. He proposed that this structure enabled the axon’s oriented growth in response to attractants, now known as chemotropic molecules. He further proposed that the physical properties of the surrounding tissues could influence the growth cone and the direction of growth. This seminal discovery afforded a plausible explanation for directed axonal growth and has led to the discovery of axon guidance mechanisms that include diffusible attractants and repellants and guidance cues anchored to cell membranes or extracellular matrix. In this review the major events in the development of this field are discussed.

Evaluation of C.L.I.N.D.E. as potent peripheral-type benzodiazepine receptor tracer in a rat model of micro-glial activation

Energy Technology Data Exchange (ETDEWEB)

Arlicot, N.; Guilloteau, D.; Chalon, S. [Institut National de la Sante et de la Recherche Medicale (INSERM), U619, 37 - Tours (France); Universite Francois Rabelais de Tours, 37 (France); Katsifis, A.; Mattner, F. [ANSTO, Sydney (Australia)

2008-02-15

The peripheral-type benzodiazepine receptors (P.B.R.) are localized in mitochondria of glial cells and are very low expressed in normal brain. Their expression rises after micro-glial activation consecutive to brain injury. Accordingly, P.B.R. are potential targets to evaluate neuro inflammatory changes in a variety of C.N.S. disorders. To date no effective tool is available to explore P.B.R. by SPECT. We characterized here 6-chloro-2-(4 iodophenyl)-3-(N,N-diethyl)-imidazo[1,2-a]pyridine- 3-acetamide, C.L.I.N.D.E., in a rat model of excitotoxic lesion. Excitotoxicity was induced in male Wistar rats by unilateral intra striatal injection of different amounts of quinolinic acid (Q.A.: 75, 150 or 300 nmol). One week later, 2 groups of rats (n = 5-6/group) were i.v. injected with [{sup 125}I]-C.L.I.N.D.E. (0.4 MBq), one group being pre-injected with P.K.11195 (5 mg/kg). Brains were removed 30 min after tracer injection and the radioactivity of cerebral areas measured. Complementary ex vivo autoradiography and immunohistochemical studies using O.X.-42 were performed on brain sections In the control group, [{sup 125}I]-C.L.I.N.D.E. binding was significantly higher ( p < 0.001) in lesioned than that in intact side (striatum: 0.552 {+-} 0.109 vs. 0.123 {+-} 0.012% I.D./g tissue; cortex: 0.385 {+-} 0.126 vs. 0.131 {+-} 0.007% with 300 nmol Q.A.). This binding disappeared in rats pretreated with P.K.11195 ( p < 0.001), showing specific binding of C.L.I.N.D.E. to P.B.R.. Ex vivo autoradiography and immunohistochemistry were consistent with this, revealing a spatial correspondence between radioactivity signal and activated micro-glia. Regression analysis yielded a significant correlation ( p < 0.001) between the ligand binding and the dose of Q.A.. These results demonstrate that C.L.I.N.D.E. is suitable for P.B.R. in vivo SPECT imaging to explore their involvement in neuro degenerative disorders associated with micro-glial activation. (authors)

Effect of radiomodifying agents on the ratios of X-ray-induced lesions in cellular DNA: use in lethal lesion determination

International Nuclear Information System (INIS)

Radford, I.R.

1986-01-01

The effect of three radiomodifying agents, cysteamine, hyperthermia, and hypoxia, on the induction of the major classes of X-ray-induced DNA lesions, was studied using mouse L cells and Chinese hamster V79 cells. The use of filter elution techniques allowed most of these studies to be conducted at X-ray doses within the survival-curve range. Cysteamine was found to protect against DNA single-strand breakage (ssb), DNA base damage, and DNA-protein crosslinkage. Hyperthermia had no effect on the level of DNA ssb or DNA base damage, but in L cells (but not in V79 cells) it increased the level of DNA-protein crosslinkage relative to DNA ssb. Hypoxia protected against DNA ssb, had no significant effect on the level of DNA base damage, and enhanced the level of DNA-protein crosslinkage relative to DNA ssb. These results support the previous suggestion that the X-ray-induced lethal lesion is DNA double-strand breakage. Implications of these findings for the mechanisms of formation of X-ray-induced DNA lesions are also discussed. (author)

Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation.

Science.gov (United States)

Rocha, Sandra M; Saraiva, Tatiana; Cristóvão, Ana C; Ferreira, Raquel; Santos, Tiago; Esteves, Marta; Saraiva, Cláudia; Je, Goun; Cortes, Luísa; Valero, Jorge; Alves, Gilberto; Klibanov, Alexander; Kim, Yoon-Seong; Bernardino, Liliana

2016-06-04

Histamine is an amine widely known as a peripheral inflammatory mediator and as a neurotransmitter in the central nervous system. Recently, it has been suggested that histamine acts as an innate modulator of microglial activity. Herein, we aimed to disclose the role of histamine in microglial phagocytic activity and reactive oxygen species (ROS) production and to explore the consequences of histamine-induced neuroinflammation in dopaminergic (DA) neuronal survival. The effect of histamine on phagocytosis was assessed both in vitro by using a murine N9 microglial cell line and primary microglial cell cultures and in vivo. Cells were exposed to IgG-opsonized latex beads or phosphatidylserine (PS) liposomes to evaluate Fcγ or PS receptor-mediated microglial phagocytosis, respectively. ROS production and protein levels of NADPH oxidases and Rac1 were assessed as a measure of oxidative stress. DA neuronal survival was evaluated in vivo by counting the number of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) of mice. We found that histamine triggers microglial phagocytosis via histamine receptor 1 (H1R) activation and ROS production via H1R and H4R activation. By using apocynin, a broad NADPH oxidase (Nox) inhibitor, and Nox1 knockout mice, we found that the Nox1 signaling pathway is involved in both phagocytosis and ROS production induced by histamine in vitro. Interestingly, both apocynin and annexin V (used as inhibitor of PS-induced phagocytosis) fully abolished the DA neurotoxicity induced by the injection of histamine in the SN of adult mice in vivo. Blockade of H1R protected against histamine-induced Nox1 expression and death of DA neurons in vivo. Overall, our results highlight the relevance of histamine in the modulation of microglial activity that ultimately may interfere with neuronal survival in the context of Parkinson's disease (PD) and, eventually, other neurodegenerative diseases which are accompanied by microglia-induced

Redundant dopaminergic activity may enable compensatory axonal sprouting in Parkinson disease.

Science.gov (United States)

Arkadir, David; Bergman, Hagai; Fahn, Stanley

2014-03-25

Neurodegenerative diseases become clinically apparent only after a substantial population of neurons is lost. This raises the possibility of compensatory mechanisms in the early phase of these diseases. The importance of understanding these mechanisms cannot be underestimated because it may guide future disease-modifying strategies. Because the anatomy and physiology of the nigrostriatal dopaminergic pathways have been well described, the study of Parkinson disease can offer insight into these early compensatory mechanisms. Collateral axonal sprouting of dopaminergic terminals into the denervated striatum is the most studied compensatory mechanism in animal (almost exclusively rodent) models of Parkinson disease and is correlated with behavioral recovery after partial lesions. This sprouting, however, does not respect the normal anatomy of the original nigrostriatal pathways and leads to aberrant neuronal networks. We suggest here that the unique physiologic property of the dopaminergic innervation of the striatum, namely redundancy of information encoding, is crucial to the efficacy of compensatory axonal sprouting in the presence of aberrant anatomical connections. Redundant information encoding results from the similarity of representation of salient and rewarding events by many dopaminergic neurons, from the wide axonal field of a single dopaminergic neuron in the striatum, and from the nonspecific spatial effect of dopamine on striatal neurons (volume conductance). Finally, we discuss the relevance of these findings in animal models to human patients with Parkinson disease.

The Role of MAC1 in Diesel Exhaust Particle-induced Microglial Activation and Loss of Dopaminergic Neuron Function

OpenAIRE

Levesque, Shannon; Taetzsch, Thomas; Lull, Melinda E.; Johnson, Jo Anne; McGraw, Constance; Block, Michelle L.

2013-01-01

Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson’s disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (

Axon degeneration: make the Schwann cell great again

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Keit Men Wong

2017-01-01

Full Text Available Axonal degeneration is a pivotal feature of many neurodegenerative conditions and substantially accounts for neurological morbidity. A widely used experimental model to study the mechanisms of axonal degeneration is Wallerian degeneration (WD, which occurs after acute axonal injury. In the peripheral nervous system (PNS, WD is characterized by swift dismantling and clearance of injured axons with their myelin sheaths. This is a prerequisite for successful axonal regeneration. In the central nervous system (CNS, WD is much slower, which significantly contributes to failed axonal regeneration. Although it is well-documented that Schwann cells (SCs have a critical role in the regenerative potential of the PNS, to date we have only scarce knowledge as to how SCs 'sense' axonal injury and immediately respond to it. In this regard, it remains unknown as to whether SCs play the role of a passive bystander or an active director during the execution of the highly orchestrated disintegration program of axons. Older reports, together with more recent studies, suggest that SCs mount dynamic injury responses minutes after axonal injury, long before axonal breakdown occurs. The swift SC response to axonal injury could play either a pro-degenerative role, or alternatively a supportive role, to the integrity of distressed axons that have not yet committed to degenerate. Indeed, supporting the latter concept, recent findings in a chronic PNS neurodegeneration model indicate that deactivation of a key molecule promoting SC injury responses exacerbates axonal loss. If this holds true in a broader spectrum of conditions, it may provide the grounds for the development of new glia-centric therapeutic approaches to counteract axonal loss.

Npn-1 contributes to axon-axon interactions that differentially control sensory and motor innervation of the limb.

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Rosa-Eva Huettl

2011-02-01

Full Text Available The initiation, execution, and completion of complex locomotor behaviors are depending on precisely integrated neural circuitries consisting of motor pathways that activate muscles in the extremities and sensory afferents that deliver feedback to motoneurons. These projections form in tight temporal and spatial vicinities during development, yet the molecular mechanisms and cues coordinating these processes are not well understood. Using cell-type specific ablation of the axon guidance receptor Neuropilin-1 (Npn-1 in spinal motoneurons or in sensory neurons in the dorsal root ganglia (DRG, we have explored the contribution of this signaling pathway to correct innervation of the limb. We show that Npn-1 controls the fasciculation of both projections and mediates inter-axonal communication. Removal of Npn-1 from sensory neurons results in defasciculation of sensory axons and, surprisingly, also of motor axons. In addition, the tight coupling between these two heterotypic axonal populations is lifted with sensory fibers now leading the spinal nerve projection. These findings are corroborated by partial genetic elimination of sensory neurons, which causes defasciculation of motor projections to the limb. Deletion of Npn-1 from motoneurons leads to severe defasciculation of motor axons in the distal limb and dorsal-ventral pathfinding errors, while outgrowth and fasciculation of sensory trajectories into the limb remain unaffected. Genetic elimination of motoneurons, however, revealed that sensory axons need only minimal scaffolding by motor axons to establish their projections in the distal limb. Thus, motor and sensory axons are mutually dependent on each other for the generation of their trajectories and interact in part through Npn-1-mediated fasciculation before and within the plexus region of the limbs.

EFA6 regulates selective polarised transport and axon regeneration from the axon initial segment

Czech Academy of Sciences Publication Activity Database

Eva, R.; Koseki, H.; Kanamarlapudi, V.; Fawcett, James

2017-01-01

Roč. 130, č. 21 (2017), s. 3663-3675 ISSN 0021-9533 Institutional support: RVO:68378041 Keywords : axon regeneration * axon transport * neuronal polarisation Subject RIV: FH - Neurology OBOR OECD: Neuroscience s (including psychophysiology Impact factor: 4.431, year: 2016

Gastroprotective effect of esculin on ethanol-induced gastric lesion in mice.

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Li, Weifeng; Wang, Yu; Wang, Xiumei; Zhang, Hailin; He, Zehong; Zhi, Wenbing; Liu, Fang; Niu, Xiaofeng

2017-04-01

The gastroprotective effect of esculin was investigated in a mouse model of ethanol-induced gastric lesion. Administration of esculin at doses of 5, 10, and 20 mg/kg body weight prior to ethanol ingestion led to significant gastroprotection compared with untreated mice. Gastric mucosal lesions were evaluated by macroscopic and histopathological alterations, lesion index, and myeloperoxidase (MPO) activity. Pretreatment with esculin significantly reduced macroscopic and histopathological damage, gastric lesion index, and MPO activity in a dose-dependent manner. Moreover, esculin significantly reduced nitric oxide (NO) production, inducible NO synthase (iNOS) levels, and nuclear factor-kappa B (NF-κB) p65 protein expression in gastric tissues after ethanol challenge. Analysis of inflammatory cytokines indicated that esculin pretreatment markedly suppressed the increased expression of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in ethanol-treated mice. The results demonstrate a protective effect of esculin against gastric injury and suggest that the underlying mechanism might be associated with inhibition of NF-κB activation, which subsequently reduces expression of iNOS, TNF-α, and IL-6. © 2016 Société Française de Pharmacologie et de Thérapeutique.

Dynamics of mitochondrial transport in axons

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Robert Francis Niescier

2016-05-01

Full Text Available The polarized structure and long neurites of neurons pose a unique challenge for proper mitochondrial distribution. It is widely accepted that mitochondria move from the cell body to axon ends and vice versa; however, we have found that mitochondria originating from the axon ends moving in the retrograde direction never reach to the cell body, and only a limited number of mitochondria moving in the anterograde direction from the cell body arrive at the axon ends of mouse hippocampal neurons. Furthermore, we have derived a mathematical formula using the Fokker-Planck equation to characterize features of mitochondrial transport, and the equation could determine altered mitochondrial transport in axons overexpressing parkin. Our analysis will provide new insights into the dynamics of mitochondrial transport in axons of normal and unhealthy neurons.

Headmasters: Microglial regulation of learning and memory in health and disease

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Laetitia Weinhard

2018-03-01

Full Text Available Microglia are mononuclear phagocytes that reside throughout the lifetime of the animal in the central nervous system (CNS. Originating from the yolk sac, microglial progenitors infiltrate the developing brain anlage even before the formation of the neural network. Mature microglial cells persist by slow rates of self-renewal that vary across brain regions. Eminent studies in the recent decade have highlighted a role for steady state microglia in neurogenesis, synaptic pruning, and formation and maintenance of connectivity within the CNS, which are critical to learning and memory functions. Activity- and learning-dependent synaptic remodeling by microglia has been described in various contexts. Molecular pathways, including signaling through fractalkine CX3CL1 and its receptor CX3CR1, transforming growth factor-beta, classical complement system, colony-stimulating factor 1 receptor, adaptor protein DAP12, and brain-derived neurotropic factor, have been proposed to be important mediators of synaptic plasticity regulated by microglia. Reactive, dysfunctional, or aged microglia are thought to impact learning and memory, and are implicated in human neurodegenerative disorders in which dementia is a hallmark. These disorders include Nasu-Hakola disease, hereditary diffuse leukoencephaly with spheroids, Alzheimer’s disease, frontotemporal dementia, and Parkinson’s disease. Focusing on microglia, here we discuss the potential detrimental effects and risks presented by microglia-specific genetic variants, the environmental factors that target microglia, and microglial aging that likely lead to progressive memory loss in neurodegenerative diseases. Finally, we consider some caveats of the animal model systems that to date have advanced our understanding of microglial regulation of learning and memory.

Nebula/DSCR1 upregulation delays neurodegeneration and protects against APP-induced axonal transport defects by restoring calcineurin and GSK-3β signaling.

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Shaw, Jillian L; Chang, Karen T

2013-01-01

Post-mortem brains from Down syndrome (DS) and Alzheimer's disease (AD) patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1), but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP), which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3β signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3β signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD.

Oxidized low density lipoprotein induced caspase-1 mediated pyroptotic cell death in macrophages: implication in lesion instability?

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Jing Lin

Full Text Available BACKGROUND: Macrophage death in advanced lesion has been confirmed to play an important role in plaque instability. However, the mechanism underlying lesion macrophage death still remains largely unknown. METHODS AND RESULTS: Immunohistochemistry showed that caspase-1 activated in advanced lesion and co-located with macrophages and TUNEL positive reaction. In in-vitro experiments showed that ox-LDL induced caspase-1 activation and this activation was required for ox-LDL induced macrophages lysis, IL-1β and IL-18 production as well as DNA fragmentation. Mechanism experiments showed that CD36 and NLRP3/caspase-1/pathway involved in ox-LDL induced macrophage pyroptosis. CONCLUSION: Our study here identified a novel cell death, pyroptosis in ox-LDL induced human macrophage, which may be implicated in lesion macrophages death and play an important role in lesion instability.

Acetyl-L-Carnitine via Upegulating Dopamine D1 Receptor and Attenuating Microglial Activation Prevents Neuronal Loss and Improves Memory Functions in Parkinsonian Rats.

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Singh, Sonu; Mishra, Akanksha; Srivastava, Neha; Shukla, Rakesh; Shukla, Shubha

2018-01-01

Parkinson's disease is accompanied by nonmotor symptoms including cognitive impairment, which precede the onset of motor symptoms in patients and are regulated by dopamine (DA) receptors and the mesocorticolimbic pathway. The relative contribution of DA receptors and astrocytic glutamate transporter (GLT-1) in cognitive functions is largely unexplored. Similarly, whether microglia-derived increased immune response affects cognitive functions and neuronal survival is not yet understood. We have investigated the effect of acetyl-L-carnitine (ALCAR) on cognitive functions and its possible underlying mechanism of action in 6-hydroxydopamine (6-OHDA)-induced hemiparkinsonian rats. ALCAR treatment in 6-OHDA-lesioned rats improved memory functions as confirmed by decreased latency time and path length in the Morris water maze test. ALCAR further enhanced D1 receptor levels without altering D2 receptor levels in the hippocampus and prefrontal cortex (PFC) regions, suggesting that the D1 receptor is preferentially involved in the regulation of cognitive functions. ALCAR attenuated microglial activation and release of inflammatory mediators through balancing proinflammatory and anti-inflammatory cytokines, which subsequently enhanced the survival of mature neurons in the CA1, CA3, and PFC regions and improved cognitive functions in hemiparkinsonian rats. ALCAR treatment also improved glutathione (GSH) content, while decreasing oxidative stress indices, inducible nitrogen oxide synthase (iNOS) levels, and astrogliosis resulting in the upregulation of GLT-1 levels. Additionally, ALCAR prevented the loss of dopaminergic (DAergic) neurons in ventral tagmental area (VTA)/substantia nigra pars compacta (SNpc) regions of 6-OHDA-lesioned rats, thus maintaining the integrity of the nigrostriatal pathway. Together, these results demonstrate that ALCAR treatment in hemiparkinsonian rats ameliorates neurodegeneration and cognitive deficits, hence suggesting its therapeutic potential in

Nonhemorrhagic brain lesions detected by magnetic resonance imaging in closed head injured patients

International Nuclear Information System (INIS)

Kinoshita, Yoshihiro; Hiraide, Atsushi; Yoshioka, Toshiji; Sugimoto, Tadashi; Ichimura, Teruhisa; Saito, Akira; Ohno, Yoshioki.

1990-01-01

This study evaluated the diagnostic usefulness of magnetic resonance imaging (MRI) in 83 closed head injured patients in whom CT failed to detect focal intra or extraaxial hematoma and/or apparent brain contusion. The patients were divided into three groups on the basis of unconsciousness duration: Group 1 comprised 50 patients diagnosed as having classical cerebral concussion; group 2 comprised 19 patients who presented to the hospital with 6-hr unconsciousness and was recovered within a week; and group 3 comprised 14 patients whose unconsciousness persisted for a week or more. There was no CT evidence of abnormal findings for group 1; and intraventricular hemorrhage and subarachnoid hemorrhage were visualized on CT in 26% and 16%, respectively, for group 2 and 71% and 14% for group 3. Intraaxial nonhemorrhagic lesions were detected on T2-weighted MRI. According to high signal intensity, diffuse axonal injury and cortical contusion could be distinguished; i.e., in the former the corpus callosum, basal ganglia, or brain stem showed a high signal intensity, and in the latter the frontal, temporal, or parietal lobe adjacent to the skull showed a low signal intensity. T2-weighted MRI revealed cortical contusion in 6% for group 1, 37% for group 2, and 14% for group 3; and diffuse axonal injury in 42% for group 2 and 79% for group 3. For 62 patients with normal CT findings, diffuse axonal injury was detected in 88%. There was a good correlation between intraventricular hemorrhage on CT and diffuse axonal injury on MRI. In conclusion, T2-weighted MRI was significantly superior to CT in detecting nonhemorrhagic lesions, and it was of great help for predicting neurologic recovery in closed head injured patients without apparent focal lesions on CT. (N.K.)

Radiation-induced lesions of the aorta

Energy Technology Data Exchange (ETDEWEB)

Doessing, M; Rasmussen, S [Medical Department C, Diakonissestiftelsen, Copenhagen (Denmark); Fischer-Hansen, B; Walbom-Joergensen, S

1977-04-09

A description is given of pathological changes detected in the aortic arch of a 21-year-old man. The patient died from an acute myocardial infarction 16 months after a dose of 3696 rads to a mantle field for Hodgkin's disease confined to the midcervical lymph nodes on the left side of the neck. Histological examination of the exposed part of the aortic arch showed the wall to be focally thickened owing to a pronounced fibrosis of the luminal third of the wall. The elastic lamellae in this area were reduced in number, broken up, and haphazardly arranged. The intima appeared normal. There was no leucocytic infiltration, no proliferation of vasa vasorum and no significant adventitial fibrosis. It is suggested that these noncharacteristic changes may have been early radiation-induced lesions which later might induce fibrotic scarring with perhaps clinically evident disease.

The PPARα Agonist Fenofibrate Preserves Hippocampal Neurogenesis and Inhibits Microglial Activation After Whole-Brain Irradiation

International Nuclear Information System (INIS)

Ramanan, Sriram; Kooshki, Mitra; Zhao Weiling; Hsu, F.-C.; Riddle, David R.; Robbins, Mike E.

2009-01-01

Purpose: Whole-brain irradiation (WBI) leads to cognitive impairment months to years after radiation. Numerous studies suggest that decreased hippocampal neurogenesis and microglial activation are involved in the pathogenesis of WBI-induced brain injury. The goal of this study was to investigate whether administration of the peroxisomal proliferator-activated receptor (PPAR) α agonist fenofibrate would prevent the detrimental effect of WBI on hippocampal neurogenesis. Methods and Materials: For this study, 129S1/SvImJ wild-type and PPARα knockout mice that were fed either regular or 0.2% wt/wt fenofibrate-containing chow received either sham irradiation or WBI (10-Gy single dose of 137 Cs γ-rays). Mice were injected intraperitoneally with bromodeoxyuridine to label the surviving cells at 1 month after WBI, and the newborn neurons were counted at 2 months after WBI by use of bromodeoxyuridine/neuronal nuclei double immunofluorescence. Proliferation in the subgranular zone and microglial activation were measured at 1 week and 2 months after WBI by use of Ki-67 and CD68 immunohistochemistry, respectively. Results: Whole-brain irradiation led to a significant decrease in the number of newborn hippocampal neurons 2 months after it was performed. Fenofibrate prevented this decrease by promoting the survival of newborn cells in the dentate gyrus. In addition, fenofibrate treatment was associated with decreased microglial activation in the dentate gyrus after WBI. The neuroprotective effects of fenofibrate were abolished in the knockout mice, indicating a PPARα-dependent mechanism or mechanisms. Conclusions: These data highlight a novel role for PPARα ligands in improving neurogenesis after WBI and offer the promise of improving the quality of life for brain cancer patients receiving radiotherapy.

Axonal degeneration in association with carpal tunnel syndrome Degeneração axonal na síndrome do túnel do carpo

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Marcelo Ribeiro Caetano

2003-03-01

Full Text Available Median nerve entrapment in the palm to wrist segment is known as carpal tunnel syndrome (CTS. Electromyography is the best evaluation test to confirm the disease, as it shows a median reduced conduction velocity and/or conduction block; however, the usual CTS electrodiagnostic tests do not separate segmental demyelination alone from segmental demyelination plus secondary axonal degeneration. We studied 100 hands from CTS patients (classified as mild, moderate, and severe, and 50 hands from normal subjects. The median palmar sensory nerve action potential (SNAP amplitude was measured and compared between the two groups. It would be expected that SNAP was normal if no axonal degeneration had occurred. The results showed that in mild CTS group and part of moderate CTS group SNAP amplitude was normal, whereas in severe CTS group, and part of moderate group SNAP amplitude was reduced, proving that axonal degeneration was involved. As it is well stated that axonal lesions have worse prognosis than segmental demyelinating ones, this simple test may help to preditic the CTS outcome and treatment.A compressão do nervo mediano no segmento punho-palma produz uma entidade clínica conhecida como síndrome do túnel do carpo (STC. A eletroneuromiografia é o exame de escolha para o diagnóstico da STC, através da identificação de diminuição de velocidade e/ou bloqueio de condução quando estudamos a neurocondução do nervo mediano, no trecho do punho. Entretanto, as técnicas comumente usadas não conseguem separar a lesão em mielínica focal com ou sem degeneração axonal secundária. Avaliamos 100 mãos de pacientes com STC e comparamos com 50 mãos de um grupo controle. Medimos a amplitude do potencial de ação do nervo sensitivo do mediano, com estímulo na palma e captação no dedo, e comparamos entre os grupos controle e de pacientes (o grupo de STC foi subdividido em leve, moderado e grave. Era esperado que a amplitude do potencial

Formation of longitudinal axon pathways in Caenorhabditis elegans.

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Hutter, Harald

2017-11-18

The small number of neurons and the simple architecture of the Caenorhabditis elegans (C. elegans) nervous system enables researchers to study axonal pathfinding at the level of individually identified axons. Axons in C. elegans extend predominantly along one of the two major body axes, the anterior-posterior axis and the dorso-ventral axis. This review will focus on axon navigation along the anterior-posterior axis, leading to the establishment of the longitudinal axon tracts, with a focus on the largest longitudinal axon tract, the ventral nerve cord (VNC). In the VNC, axons grow out in a stereotypic order, with early outgrowing axons (pioneers) playing an important role in guiding later outgrowing (follower) axons. Genetic screens have identified a number of genes specifically affecting the formation of longitudinal axon tracts. These genes include secreted proteins, putative receptors and adhesion molecules, as well as intracellular proteins regulating the cell's response to guidance cues. In contrast to dorso-ventral navigation, no major general guidance cues required for the establishment of longitudinal pathways have been identified so far. The limited penetrance of defects found in many mutants affecting longitudinal navigation suggests that guidance cues act redundantly in this process. The majority of the axon guidance genes identified in C. elegans are evolutionary conserved, i.e. have homologs in other animals, including vertebrates. For a number of these genes, a role in axon guidance has not been described outside C. elegans. Taken together, studies in C. elegans contribute to a fundamental understanding of the molecular basis of axonal navigation that can be extended to other animals, including vertebrates and probably humans as well. Copyright © 2017. Published by Elsevier Ltd.

Axonal Membranes and Their Domains: Assembly and Function of the Axon Initial Segment and Node of Ranvier

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Andrew D. Nelson

2017-05-01

Full Text Available Neurons are highly specialized cells of the nervous system that receive, process and transmit electrical signals critical for normal brain function. Here, we review the intricate organization of axonal membrane domains that facilitate rapid action potential conduction underlying communication between complex neuronal circuits. Two critical excitable domains of vertebrate axons are the axon initial segment (AIS and the nodes of Ranvier, which are characterized by the high concentrations of voltage-gated ion channels, cell adhesion molecules and specialized cytoskeletal networks. The AIS is located at the proximal region of the axon and serves as the site of action potential initiation, while nodes of Ranvier, gaps between adjacent myelin sheaths, allow rapid propagation of the action potential through saltatory conduction. The AIS and nodes of Ranvier are assembled by ankyrins, spectrins and their associated binding partners through the clustering of membrane proteins and connection to the underlying cytoskeleton network. Although the AIS and nodes of Ranvier share similar protein composition, their mechanisms of assembly are strikingly different. Here we will cover the mechanisms of formation and maintenance of these axonal excitable membrane domains, specifically highlighting the similarities and differences between them. We will also discuss recent advances in super resolution fluorescence imaging which have elucidated the arrangement of the submembranous axonal cytoskeleton revealing a surprising structural organization necessary to maintain axonal organization and function. Finally, human mutations in axonal domain components have been associated with a growing number of neurological disorders including severe cognitive dysfunction, epilepsy, autism, neurodegenerative diseases and psychiatric disorders. Overall, this review highlights the assembly, maintenance and function of axonal excitable domains, particularly the AIS and nodes of

Dystrophic (senescent) rather than activated microglial cells are associated with tau pathology and likely precede neurodegeneration in Alzheimer's disease.

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Streit, Wolfgang J; Braak, Heiko; Xue, Qing-Shan; Bechmann, Ingo

2009-10-01

The role of microglial cells in the pathogenesis of Alzheimer's disease (AD) neurodegeneration is unknown. Although several works suggest that chronic neuroinflammation caused by activated microglia contributes to neurofibrillary degeneration, anti-inflammatory drugs do not prevent or reverse neuronal tau pathology. This raises the question if indeed microglial activation occurs in the human brain at sites of neurofibrillary degeneration. In view of the recent work demonstrating presence of dystrophic (senescent) microglia in aged human brain, the purpose of this study was to investigate microglial cells in situ and at high resolution in the immediate vicinity of tau-positive structures in order to determine conclusively whether degenerating neuronal structures are associated with activated or with dystrophic microglia. We used a newly optimized immunohistochemical method for visualizing microglial cells in human archival brain together with Braak staging of neurofibrillary pathology to ascertain the morphology of microglia in the vicinity of tau-positive structures. We now report histopathological findings from 19 humans covering the spectrum from none to severe AD pathology, including patients with Down's syndrome, showing that degenerating neuronal structures positive for tau (neuropil threads, neurofibrillary tangles, neuritic plaques) are invariably colocalized with severely dystrophic (fragmented) rather than with activated microglial cells. Using Braak staging of Alzheimer neuropathology we demonstrate that microglial dystrophy precedes the spread of tau pathology. Deposits of amyloid-beta protein (Abeta) devoid of tau-positive structures were found to be colocalized with non-activated, ramified microglia, suggesting that Abeta does not trigger microglial activation. Our findings also indicate that when microglial activation does occur in the absence of an identifiable acute central nervous system insult, it is likely to be the result of systemic infectious

Antipsychotics, chlorpromazine and haloperidol inhibit voltage-gated proton currents in BV2 microglial cells.

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Shin, Hyewon; Song, Jin-Ho

2014-09-05

Microglial dysfunction and neuroinflammation are thought to contribute to the pathogenesis of schizophrenia. Some antipsychotic drugs have anti-inflammatory activity and can reduce the secretion of pro-inflammatory cytokines and reactive oxygen species from activated microglial cells. Voltage-gated proton channels on the microglial cells participate in the generation of reactive oxygen species and neuronal toxicity by supporting NADPH oxidase activity. In the present study, we examined the effects of two typical antipsychotics, chlorpromazine and haloperidol, on proton currents in microglial BV2 cells using the whole-cell patch clamp method. Chlorpromazine and haloperidol potently inhibited proton currents with IC50 values of 2.2 μM and 8.4 μM, respectively. Chlorpromazine and haloperidol are weak bases that can increase the intracellular pH, whereby they reduce the proton gradient and affect channel gating. Although the drugs caused a marginal positive shift of the activation voltage, they did not change the reversal potential. This suggested that proton current inhibition was not due to an alteration of the intracellular pH. Chlorpromazine and haloperidol are strong blockers of dopamine receptors. While dopamine itself did not affect proton currents, it also did not alter proton current inhibition by the two antipsychotics, indicating dopamine receptors are not likely to mediate the proton current inhibition. Given that proton channels are important for the production of reactive oxygen species and possibly pro-inflammatory cytokines, the anti-inflammatory and antipsychotic activities of chlorpromazine and haloperidol may be partly derived from their ability to inhibit microglial proton currents. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental Demyelination and Axonal Loss Are Reduced in MicroRNA-146a Deficient Mice

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Nellie A. Martin

2018-03-01

Full Text Available BackgroundThe cuprizone (CPZ model of multiple sclerosis (MS was used to identify microRNAs (miRNAs related to in vivo de- and remyelination. We further investigated the role of miR-146a in miR-146a-deficient (KO mice: this miRNA is differentially expressed in MS lesions and promotes differentiation of oligodendrocyte precursor cells (OPCs during remyelination, but its role has not been examined during demyelination.MethodsMicroRNAs were examined by Agilent Mouse miRNA Microarray in the corpus callosum during CPZ-induced demyelination and remyelination. Demyelination, axonal loss, changes in number of oligodendrocytes, OPCs, and macrophages/microglia was compared by histology/immunohistochemistry between KO and WT mice. Differential expression of target genes and proteins of miR-146a was analyzed in the transcriptome (4 × 44K Agilent Whole Mouse Genome Microarray and proteome (liquid chromatography tandem mass spectrometry of CPZ-induced de- and remyelination in WT mice. Levels of proinflammatory molecules in the corpus callosum were compared in WT versus KO mice by Meso Scale Discovery multiplex protein analysis.ResultsmiR-146a was increasingly upregulated during CPZ-induced de- and remyelination. The absence of miR-146a in KO mice protected against demyelination, axonal loss, body weight loss, and atrophy of thymus and spleen. The number of CNP+ oligodendrocytes was increased during demyelination in the miR-146a KO mice, while there was a trend of increased number of NG2+ OPCs in the WT mice. miR-146a target genes, SNAP25 and SMAD4, were downregulated in the proteome of demyelinating corpus callosum in WT mice. Higher levels of SNAP25 were measured by ELISA in the corpus callosum of miR-146a KO mice, but there was no difference between KO and WT mice during demyelination. Multiplex protein analysis of the corpus callosum lysate revealed upregulated TNF-RI, TNF-RII, and CCL2 in the WT mice in contrast to KO mice. The number of Mac3+ and

A Novel Growth-Promoting Pathway Formed by GDNF-Overexpressing Schwann Cells Promotes Propriospinal Axonal Regeneration, Synapse formation, and Partial Recovery of Function after Spinal Cord Injury

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Deng, Lingxiao; Deng, Ping; Ruan, Yiwen; Xu, Zao Cheng; Liu, Naikui; Wen, Xuejun; Smith, George M.; Xu, Xiao-Ming

2013-01-01

Descending propriospinal neurons (DPSN) are known to establish functional relays for supraspinal signals, and they display a greater growth response after injury than do the long projecting axons. However, their regenerative response is still deficient due to their failure to depart from growth supportive cellular transplants back into the host spinal cord, which contains numerous impediments to axon growth. Here we report the construction of a continuous growth-promoting pathway in adult rats, formed by grafted Schwann cells (SCs) overexpressing glial cell line-derived neurotrophic factor (GDNF). We demonstrate that such a growth-promoting pathway, extending from the axonal cut ends to the site of innervation in the distal spinal cord, promoted regeneration of DPSN axons through and beyond the lesion gap of a spinal cord hemisection. Within the distal host spinal cord, regenerated DPSN axons formed synapses with host neurons leading to the restoration of action potentials and partial recovery of function. PMID:23536080

Increased sensitivity of DNA damage response-deficient cells to stimulated microgravity-induced DNA lesions.

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Nan Li

Full Text Available Microgravity is a major stress factor that astronauts have to face in space. In the past, the effects of microgravity on genomic DNA damage were studied, and it seems that the effect on genomic DNA depends on cell types and the length of exposure time to microgravity or simulated microgravity (SMG. In this study we used mouse embryonic stem (MES and mouse embryonic fibroblast (MEF cells to assess the effects of SMG on DNA lesions. To acquire the insight into potential mechanisms by which cells resist and/or adapt to SMG, we also included Rad9-deleted MES and Mdc1-deleted MEF cells in addition to wild type cells in this study. We observed significant SMG-induced DNA double strand breaks (DSBs in Rad9-/- MES and Mdc1-/- MEF cells but not in their corresponding wild type cells. A similar pattern of DNA single strand break or modifications was also observed in Rad9-/- MES. As the exposure to SMG was prolonged, Rad9-/- MES cells adapted to the SMG disturbance by reducing the induced DNA lesions. The induced DNA lesions in Rad9-/- MES were due to SMG-induced reactive oxygen species (ROS. Interestingly, Mdc1-/- MEF cells were only partially adapted to the SMG disturbance. That is, the induced DNA lesions were reduced over time, but did not return to the control level while ROS returned to a control level. In addition, ROS was only partially responsible for the induced DNA lesions in Mdc1-/- MEF cells. Taken together, these data suggest that SMG is a weak genomic DNA stress and can aggravate genomic instability in cells with DNA damage response (DDR defects.

Impaired Mitochondrial Dynamics Underlie Axonal Defects in Hereditary Spastic Paraplegias.

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Denton, Kyle; Mou, Yongchao; Xu, Chong-Chong; Shah, Dhruvi; Chang, Jaerak; Blackstone, Craig; Li, Xue-Jun

2018-05-02

Mechanisms by which long corticospinal axons degenerate in hereditary spastic paraplegia (HSP) are largely unknown. Here, we have generated induced pluripotent stem cells (iPSCs) from patients with two autosomal recessive forms of HSP, SPG15 and SPG48, which are caused by mutations in the ZFYVE26 and AP5Z1 genes encoding proteins in the same complex, the spastizin and AP5Z1 proteins, respectively. In patient iPSC-derived telencephalic glutamatergic and midbrain dopaminergic neurons, neurite number, length and branching are significantly reduced, recapitulating disease-specific phenotypes. We analyzed mitochondrial morphology and noted a significant reduction in both mitochondrial length and their densities within axons of these HSP neurons. Mitochondrial membrane potential was also decreased, confirming functional mitochondrial defects. Notably, mdivi-1, an inhibitor of the mitochondrial fission GTPase DRP1, rescues mitochondrial morphology defects and suppresses the impairment in neurite outgrowth and late-onset apoptosis in HSP neurons. Furthermore, knockdown of these HSP genes causes similar axonal defects, also mitigated by treatment with mdivi-1. Finally, neurite outgrowth defects in SPG15 and SPG48 cortical neurons can be rescued by knocking down DRP1 directly. Thus, abnormal mitochondrial morphology caused by an imbalance of mitochondrial fission and fusion underlies specific axonal defects and serves as a potential therapeutic target for SPG15 and SPG48.

Impact of Lesion Placement on Efficacy and Safety of Catheter-Based Radiofrequency Renal Denervation.

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Mahfoud, Felix; Tunev, Stefan; Ewen, Sebastian; Cremers, Bodo; Ruwart, Jennifer; Schulz-Jander, Daniel; Linz, Dominik; Davies, Justin; Kandzari, David E; Whitbourn, Robert; Böhm, Michael; Melder, Robert J

2015-10-20

Insufficient procedural efficacy has been proposed to explain nonresponse to renal denervation (RDN). The aim of this study was to examine the impact of different patterns of lesion placements on the efficacy and consistency of catheter-based radiofrequency RDN in pigs. The impact of increasing number of lesions versus location of RDN was investigated in a porcine model (Group 1; n = 51). The effect of treating the main artery, the branches, and the 2 combined was compared in Group 2 (n = 48). The durability of response and safety of combined treatment of the main artery plus branches was examined in Group 3 (n = 16). Renal norepinephrine (NE) tissue content and renal cortical axon density were assessed. Increasing the number of RF lesions (4, 8, and 12) in the main renal artery was not sufficient to yield a clear dose-response relationship on NE content and axon density. In contrast, targeted treatment of the renal artery branches or distal segment of the main renal artery resulted in markedly less variability of response and significantly greater reduction of both NE and axon density than conventional treatment of only the main renal artery. Combination treatment (main artery plus branches) produced the greatest change in renal NE and axon density with the least heterogeneity. The changes were durable through 28 days post-treatment. These data provide the rationale for investigation of an optimized approach for RDN in future clinical studies. This may have profound implications for the clinical application of RDN, as this approach may not only achieve greater reductions in sympathetic activity but also reduce treatment effect variability. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Cargo distributions differentiate pathological axonal transport impairments.

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Mitchell, Cassie S; Lee, Robert H

2012-05-07

Axonal transport is an essential process in neurons, analogous to shipping goods, by which energetic and cellular building supplies are carried downstream (anterogradely) and wastes are carried upstream (retrogradely) by molecular motors, which act as cargo porters. Impairments in axonal transport have been linked to devastating and often lethal neurodegenerative diseases, such as Amyotrophic Lateral Sclerosis, Huntington's, and Alzheimer's. Axonal transport impairment types include a decrease in available motors for cargo transport (motor depletion), the presence of defective or non-functional motors (motor dilution), and the presence of increased or larger cargos (protein aggregation). An impediment to potential treatment identification has been the inability to determine what type(s) of axonal transport impairment candidates that could be present in a given disease. In this study, we utilize a computational model and common axonal transport experimental metrics to reveal the axonal transport impairment general characteristics or "signatures" that result from three general defect types of motor depletion, motor dilution, and protein aggregation. Our results not only provide a means to discern these general impairments types, they also reveal key dynamic and emergent features of axonal transport, which potentially underlie multiple impairment types. The identified characteristics, as well as the analytical method, can be used to help elucidate the axonal transport impairments observed in experimental and clinical data. For example, using the model-predicted defect signatures, we identify the defect candidates, which are most likely to be responsible for the axonal transport impairments in the G93A SOD1 mouse model of ALS. Copyright © 2012 Elsevier Ltd. All rights reserved.

Axon initial segment Kv1 channels control axonal action potential waveform and synaptic efficacy

NARCIS (Netherlands)

Kole, Maarten H. P.; Letzkus, Johannes J.; Stuart, Greg J.

2007-01-01

Action potentials are binary signals that transmit information via their rate and temporal pattern. In this context, the axon is thought of as a transmission line, devoid of a role in neuronal computation. Here, we show a highly localized role of axonal Kv1 potassium channels in shaping the action

Elucidation of axonal transport by radioautography

International Nuclear Information System (INIS)

Droz, Bernard.

1979-01-01

Radioautography permits to distinguish various pathways within the axons: the axoplasm which includes soluble enzymes and constituents of the cytoskeleton moving with slow axoplasmic flow; the mitochondria which are conveyed as organelles; the smooth endoplasmic reticulum which ensures the fast axonal transport of membrane constituents delivered to axolemma, synaptic vesicles, presynaptic membranes or mitochondria. Furthermore radioautography makes it possible to visualize intercellular exchanges of molecules between axon and glia

Genetic Ablation of Soluble TNF Does Not Affect Lesion Size and Functional Recovery after Moderate Spinal Cord Injury in Mice

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Ditte Gry Ellman

2016-01-01

Full Text Available Traumatic spinal cord injury (SCI is followed by an instant increase in expression of the microglial-derived proinflammatory cytokine tumor necrosis factor (TNF within the lesioned cord. TNF exists both as membrane-anchored TNF (mTNF and as cleaved soluble TNF (solTNF. We previously demonstrated that epidural administration of a dominant-negative inhibitor of solTNF, XPro1595, to the contused spinal cord resulted in changes in Iba1 protein expression in microglia/macrophages, decreased lesion volume, and improved locomotor function. Here, we extend our studies using mice expressing mTNF, but no solTNF (mTNFΔ/Δ, to study the effect of genetic ablation of solTNF on SCI. We demonstrate that TNF levels were significantly decreased within the lesioned spinal cord 3 days after SCI in mTNFΔ/Δ mice compared to littermates. This decrease did, however, not translate into significant changes in other pro- and anti-inflammatory cytokines (IL-10, IL-1β, IL-6, IL-5, IL-2, CXCL1, CCL2, or CCL5, despite a tendency towards increased IL-10 and decreased IL-1β, TNFR1, and TNFR2 levels in mTNFΔ/Δ mice. In addition, microglial and leukocyte infiltration, activation state (Iba1, CD11b, CD11c, CD45, and MHCII, lesion size, and functional outcome after moderate SCI were comparable between genotypes. Collectively, our data demonstrate that genetic ablation of solTNF does not significantly modulate postlesion outcome after SCI.

The axonal cytoskeleton : from organization to function

NARCIS (Netherlands)

Kevenaar, Josta T; Hoogenraad, Casper C

The axon is the single long fiber that extends from the neuron and transmits electrical signals away from the cell body. The neuronal cytoskeleton, composed of microtubules (MTs), actin filaments and neurofilaments, is not only required for axon formation and axonal transport but also provides the

Influence of caffeine on chromosome lesions induced by chemical mutagens and radiation. 2

International Nuclear Information System (INIS)

Dimitrov, B.

1977-01-01

The modifying influence of caffeine on γ-ray induced chromosome lesions was studied by chromosome aberration anaysis. Caffeine was applied as a pre- and post-treatment agent following seed (G 1 ) and root meristem (G 2 and S) irradiation of C.capillaris. The frequency of chromosome aberrations induced in G 1 was changed neither by post- nor by pre-treatment with caffeine. This fact proves the lack of caffeine modifying effect. Applied as a post-treatment agent caffeine enhances considerably the frequency of chromosome aberrations induced in root meristem cells. This is especially valid for G 2 irradiated cells, while in S cells no synergistic effect was established between induced chromosome lesions and caffeine. The enhancement of chromosome aberration frequency produced in G 2 shows a clearly manifested dependence on the time (moment) of caffeine application post irradiation. Most considerable enhancement was obtained following post-treatment with caffeine immediately after irradiation. In the following intervals - 15 and 30 min - it decreases progressively, while after 60, 180 and 300 min no enhancing effect is observed. The probable causes for the manifestation and the lack of synergistic effect between chromosome lesions induced in the various mitotic cycle phases and caffeine are discussed. (author)

Differential effects of myostatin deficiency on motor and sensory axons.

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Jones, Maria R; Villalón, Eric; Northcutt, Adam J; Calcutt, Nigel A; Garcia, Michael L

2017-12-01

Deletion of myostatin in mice (MSTN -/- ) alters structural properties of peripheral axons. However, properties like axon diameter and myelin thickness were analyzed in mixed nerves, so it is unclear whether loss of myostatin affects motor, sensory, or both types of axons. Using the MSTN -/- mouse model, we analyzed the effects of increasing the number of muscle fibers on axon diameter, myelin thickness, and internode length in motor and sensory axons. Axon diameter and myelin thickness were increased in motor axons of MSTN -/- mice without affecting internode length or axon number. The number of sensory axons was increased without affecting their structural properties. These results suggest that motor and sensory axons establish structural properties by independent mechanisms. Moreover, in motor axons, instructive cues from the neuromuscular junction may play a role in co-regulating axon diameter and myelin thickness, whereas internode length is established independently. Muscle Nerve 56: E100-E107, 2017. © 2017 Wiley Periodicals, Inc.

Nebula/DSCR1 upregulation delays neurodegeneration and protects against APP-induced axonal transport defects by restoring calcineurin and GSK-3β signaling.

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Jillian L Shaw

Full Text Available Post-mortem brains from Down syndrome (DS and Alzheimer's disease (AD patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1, but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP, which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3β signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3β signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD.

Paeoniflorin Attenuates Inflammatory Pain by Inhibiting Microglial Activation and Akt-NF-κB Signaling in the Central Nervous System

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Bo Hu

2018-05-01

Full Text Available Background/Aims: Paeoniflorin (PF is known to have anti-inflammatory and paregoric effects, but the mechanism underlying its analgesic effect remains unclear. The aim of this study was to clarify the effect of PF on Freund’s complete adjuvant (CFA-induced inflammatory pain and explore the underlying molecular mechanism. Methods: An inflammatory pain model was established by intraplantar injection of CFA in C57BL/6J mice. After intrathecal injection of PF daily for 8 consecutive days, thermal and mechanical withdrawal thresholds, the levels of inflammatory factors TNF-α, IL-1β and IL-6, microglial activity, and the expression of Akt-NF-κB signaling pathway in the spinal cord tissue were detected by animal ethological test, cell culture, enzyme-linked immunosorbent assay, immunofluorescence histochemistry, and western blot. Results: PF inhibited the spinal microglial activation in the CFA-induced pain model. The production of proinflammatory cytokines was decreased in the central nervous system after PF treatment both in vivo and in vitro. PF further displayed a remarkable effect on inhibiting the activation of Akt-NF-κB signaling pathway in vivo and in vitro. Conclusion: These results suggest that PF is a potential therapeutic agent for inflammatory pain and merits further investigation.

In vitro enzymatic studies on the nature and repair of x-ray induced lesions in DNA

International Nuclear Information System (INIS)

Wallace, S.S.

1979-01-01

Areas studied include: purification and properties of enzyme probes for x-ray induced DNA lesions using E. Coli x-ray endonuclease and S. cerevisiae endonuclease E; use of enzymes probes; and use of physical, chemical and enzymatic probes to quantify x-ray-induced lesions in viruses and cells

In Vitro Analysis of the Role of Schwann Cells on Axonal Degeneration and Regeneration Using Sensory Neurons from Dorsal Root Ganglia.

Science.gov (United States)

López-Leal, Rodrigo; Diaz, Paula; Court, Felipe A

2018-01-01

Sensory neurons from dorsal root ganglion efficiently regenerate after peripheral nerve injuries. These neurons are widely used as a model system to study degenerative mechanisms of the soma and axons, as well as regenerative axonal growth in the peripheral nervous system. This chapter describes techniques associated to the study of axonal degeneration and regeneration using explant cultures of dorsal root ganglion sensory neurons in vitro in the presence or absence of Schwann cells. Schwann cells are extremely important due to their involvement in tissue clearance during axonal degeneration as well as their known pro-regenerative effect during regeneration in the peripheral nervous system. We describe methods to induce and study axonal degeneration triggered by axotomy (mechanical separation of the axon from its soma) and treatment with vinblastine (which blocks axonal transport), which constitute clinically relevant mechanical and toxic models of axonal degeneration. In addition, we describe three different methods to evaluate axonal regeneration using quantitative methods. These protocols constitute a valuable tool to analyze in vitro mechanisms associated to axonal degeneration and regeneration of sensory neurons and the role of Schwann cells in these processes.

Prickly pear cactus (Opuntia ficus indica var. saboten) protects against stress-induced acute gastric lesions in rats.

Science.gov (United States)

Kim, Seung Hyun; Jeon, Byung Ju; Kim, Dae Hyun; Kim, Tae Il; Lee, Hee Kyoung; Han, Dae Seob; Lee, Jong-Hwan; Kim, Tae Bum; Kim, Jung Wha; Sung, Sang Hyun

2012-11-01

The protective activity of prickly pear cactus (Opuntia ficus indica var. saboten) fruit juice and its main constituent, betanin, were evaluated against stress-induced acute gastric lesions in rats. After 6 h of water immersion restraint stress (WIRS), gastric mucosal lesions with bleeding were induced in Sprague-Dawley rats. Pretreatment of a lyophilized powder containing O. ficus indica var. saboten fruit juice and maltodextrin (OFSM) and betanin significantly reduced stress lesions (800-1600 mg/kg). Both OFSM and betanin effectively prevented the decrease in gastric mucus content as detected by alcian blue staining. In addition, OFSM significantly suppressed WIRS-induced increases in the level of gastric mucosal tumor necrosis factor-α and myeloperoxidase (MPO). Betanin alone was only effective in decreasing MPO. These results revealed the protective activity of OFSM against stress-induced acute gastric lesions and that betanin may contribute to OFSM's gastric protective activity, at least in part. When OFSM and betanin were taken together, OFSM exerted gastroprotective activity against stress-induced gastric lesions by maintaining gastric mucus, which might be related to the attenuation of MPO-mediated damage and proinflammatory cytokine production.

Targeting Microglial Activation States as a Therapeutic Avenue in Parkinson’s Disease

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Sudhakar R. Subramaniam

2017-06-01

Full Text Available Parkinson’s disease (PD is a chronic and progressive disorder characterized neuropathologically by loss of dopamine neurons in the substantia nigra, intracellular proteinaceous inclusions, reduction of dopaminergic terminals in the striatum, and increased neuroinflammatory cells. The consequent reduction of dopamine in the basal ganglia results in the classical parkinsonian motor phenotype. A growing body of evidence suggest that neuroinflammation mediated by microglia, the resident macrophage-like immune cells in the brain, play a contributory role in PD pathogenesis. Microglia participate in both physiological and pathological conditions. In the former, microglia restore the integrity of the central nervous system and, in the latter, they promote disease progression. Microglia acquire different activation states to modulate these cellular functions. Upon activation to the M1 phenotype, microglia elaborate pro-inflammatory cytokines and neurotoxic molecules promoting inflammation and cytotoxic responses. In contrast, when adopting the M2 phenotype microglia secrete anti-inflammatory gene products and trophic factors that promote repair, regeneration, and restore homeostasis. Relatively little is known about the different microglial activation states in PD and a better understanding is essential for developing putative neuroprotective agents. Targeting microglial activation states by suppressing their deleterious pro-inflammatory neurotoxicity and/or simultaneously enhancing their beneficial anti-inflammatory protective functions appear as a valid therapeutic approach for PD treatment. In this review, we summarize microglial functions and, their dual neurotoxic and neuroprotective role in PD. We also review molecules that modulate microglial activation states as a therapeutic option for PD treatment.

Hypoxia-inducible factor-1α upregulation in microglia following hypoxia protects against ischemia-induced cerebral infarction.

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Huang, Tao; Huang, Weiyi; Zhang, Zhiqiang; Yu, Lei; Xie, Caijun; Zhu, Dongan; Peng, Zizhuang; Chen, Jiehan

2014-10-01

Activated microglia were considered to be the toxic inflammatory mediators that induce neuron degeneration after brain ischemia. Hypoxia can enhance the expression of hypoxia-inducible factor-1α (HIF-1α) in microglia and cause microglial activation. However, intermittent hypoxia has been reported recently to be capable of protecting the body from myocardial ischemia. We established a high-altitude environment as the hypoxic condition in this study. The hypoxic condition displayed a neuroprotective effect after brain ischemia, and mice exposed to this condition presented better neurological performance and smaller infarct size. At the same time, a high level of HIF-1α, low level of isoform of nitric oxide synthase, and a reduction in microglial activation were also seen in ischemic focus of hypoxic mice. However, this neuroprotective effect could be blocked by 2-methoxyestradiol, the HIF-1α inhibitor. Our finding suggested that HIF-1α expression was involved in microglial activation in vitro and was regulated by oxygen supply. The microglia were inactivated by re-exposure to hypoxia, which might be due to overexpression of HIF-1α. These results indicated that hypoxic conditions can be exploited to achieve maximum neuroprotection after brain ischemia. This mechanism possibly lies in microglial inactivation through regulation of the expression of HIF-1α.

The axon-protective WLD(S) protein partially rescues mitochondrial respiration and glycolysis after axonal injury.

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Godzik, Katharina; Coleman, Michael P

2015-04-01

The axon-protective Wallerian degeneration slow (WLD(S)) protein can ameliorate the decline in axonal ATP levels after neurite transection. Here, we tested the hypothesis that this effect is associated with maintenance of mitochondrial respiration and/or glycolysis. We used isolated neurites of superior cervical ganglion (SCG) cultures in the Seahorse XF-24 Metabolic Flux Analyser to determine mitochondrial respiration and glycolysis under different conditions. We observed that both mitochondrial respiration and glycolysis declined significantly during the latent phase of Wallerian degeneration. WLD(S) partially reduced the decline both in glycolysis and in mitochondrial respiration. In addition, we found that depleting NAD levels in uncut cultures led to changes in mitochondrial respiration and glycolysis similar to those rescued by WLD(S) after cut, suggesting that the maintenance of NAD levels in Wld(S) neurites after axonal injury at least partially underlies the maintenance of ATP levels. However, by using another axon-protective mutation (Sarm1(-/-)), we could demonstrate that rescue of basal ECAR (and hence probably glycolysis) rather than basal OCR (mitochondrial respiration) may be part of the protective phenotype to delay Wallerian degeneration. These findings open new routes to study glycolysis and the connection between NAD and ATP levels in axon degeneration, which may help to eventually develop therapeutic strategies to treat neurodegenerative diseases.

Creatine pretreatment protects cortical axons from energy depletion in vitro

Science.gov (United States)

Shen, Hua; Goldberg, Mark P.

2012-01-01

Creatine is a natural nitrogenous guanidino compound involved in bioenergy metabolism. Although creatine has been shown to protect neurons of the central nervous system (CNS) from experimental hypoxia/ischemia, it remains unclear if creatine may also protect CNS axons, and if the potential axonal protection depends on glial cells. To evaluate the direct impact of creatine on CNS axons, cortical axons were cultured in a separate compartment from their somas and proximal neurites using a modified two-compartment culture device. Axons in the axon compartment were subjected to acute energy depletion, an in vitro model of white matter ischemia, by exposure to 6 mM sodium azide for 30 min in the absence of glucose and pyruvate. Energy depletion reduced axonal ATP by 65%, depolarized axonal resting potential, and damaged 75% of axons. Application of creatine (10 mM) to both compartments of the culture at 24 h prior to energy depletion significantly reduced axonal damage by 50%. In line with the role of creatine in the bioenergy metabolism, this application also alleviated the axonal ATP loss and depolarization. Inhibition of axonal depolarization by blocking sodium influx with tetrodotoxin also effectively reduced the axonal damage caused by energy depletion. Further study revealed that the creatine effect was independent of glial cells, as axonal protection was sustained even when creatine was applied only to the axon compartment (free from somas and glial cells) for as little as 2 h. In contrast, application of creatine after energy depletion did not protect axons. The data provide the first evidence that creatine pretreatment may directly protect CNS axons from energy deficiency. PMID:22521466

Prevention of hypoglycemia-induced neuronal death by minocycline

Science.gov (United States)

2012-01-01

Diabetic patients who attempt strict management of blood glucose levels frequently experience hypoglycemia. Severe and prolonged hypoglycemia causes neuronal death and cognitive impairment. There is no effective tool for prevention of these unwanted clinical sequelae. Minocycline, a second-generation tetracycline derivative, has been recognized as an anti-inflammatory and neuroprotective agent in several animal models such as stroke and traumatic brain injury. In the present study, we tested whether minocycline also has protective effects on hypoglycemia-induced neuronal death and cognitive impairment. To test our hypothesis we used an animal model of insulin-induced acute hypoglycemia. Minocycline was injected intraperitoneally at 6 hours after hypoglycemia/glucose reperfusion and injected once per day for the following 1 week. Histological evaluation for neuronal death and microglial activation was performed from 1 day to 1 week after hypoglycemia. Cognitive evaluation was conducted 6 weeks after hypoglycemia. Microglial activation began to be evident in the hippocampal area at 1 day after hypoglycemia and persisted for 1 week. Minocycline injection significantly reduced hypoglycemia-induced microglial activation and myeloperoxidase (MPO) immunoreactivity. Neuronal death was significantly reduced by minocycline treatment when evaluated at 1 week after hypoglycemia. Hypoglycemia-induced cognitive impairment is also significantly prevented by the same minocycline regimen when subjects were evaluated at 6 weeks after hypoglycemia. Therefore, these results suggest that delayed treatment (6 hours post-insult) with minocycline protects against microglial activation, neuronal death and cognitive impairment caused by severe hypoglycemia. The present study suggests that minocycline has therapeutic potential to prevent hypoglycemia-induced brain injury in diabetic patients. PMID:22998689

Distribution of ultraviolet-induced lesions in Simian Virus 40 DNA

International Nuclear Information System (INIS)

Bourre, F.; Renault, G.; Sarasin, A.; Seawell, P.C.

1985-01-01

In order to analyze the molecular mechanisms of mutagenesis in mammalian cells, we devised an analytical assay using Simian Virus 40 as biological probe. To study the possible correlations between the distribution of the lesions on the treated DNA and the distribution of mutations, we have located and quantified the lesions induced by ultraviolet light (254 nm) on a SV40 DNA fragment. At a fluence of 2,000J/m 2 , our results show that the formation frequency of thymine-thymine dimers (TT) is three to four times higher than the formation frequency of the other types of dimers (TC, CT, CC). On the other hand, the formation frequency of a dimer is influenced by the adjacent sequence. In particular, a pyrimidine in the 5' position of a thymine-thymine dimer enhances its formation frequency. At the dose used the formation frequency of the pyrimidine (6-4) pyrimidone photoproducts is twenty times less than the formation frequency of pyrimidine dimers. This paper shows the distribution of the major lesions induced by UV-light on a defined fragment of SV40 genome after UV irradiation. This work is necessary to get an insight in the molecular mechanisms of UV-mutagenesis

Cerebellum tunes the excitability of the motor system: evidence from peripheral motor axons.

Science.gov (United States)

Nodera, Hiroyuki; Manto, Mario

2014-12-01

Cerebellum is highly connected with the contralateral cerebral cortex. So far, the motor deficits observed in acute focal cerebellar lesions in human have been mainly explained on the basis of a disruption of the cerebello-thalamo-cortical projections. Cerebellar circuits have also numerous anatomical and functional interactions with brainstem nuclei and projects also directly to the spinal cord. Cerebellar lesions alter the excitability of peripheral motor axons as demonstrated by peripheral motor threshold-tracking techniques in cerebellar stroke. The biophysical changes are correlated with the functional scores. Nerve excitability measurements represent an attractive tool to extract the rules underlying the tuning of excitability of the motor pathways by the cerebellum and to discover the contributions of each cerebellar nucleus in this key function, contributing to early plasticity and sensorimotor learning.

Modification of radiation-induced DNA lesions by oxygen

International Nuclear Information System (INIS)

Meyn, R.E.; Jenkins, W.T.

1984-01-01

The efficiency of DNA strand break production by radiation under aerated and hypoxic conditions was determined in CHO cells using the technique of alkaline elution. The resulting oxygen enhancement ratio was surprisingly high, 7.8. When the pH of the elution was increased from 12.1, the normally used pH, to 12.8, a substantial increase in the strand breaks produced in the hypoxic cells was observed, resulting in an OER of 4.8. This difference in susceptibility of DNA strand break detection as a function of pH suggested a difference in the type of lesions produced in DNA when irradiated under aerated and hypoxic conditions. Further experiments to examine the DNA-protein crosslinks produced by radiation suggested that the apparent lower level of strand breaks in hypoxic cells may be due to a higher level of DNA-protein crosslinks produced under hypoxic conditions. Thus, oxygen may not only act by modifying the quantity of radiation-induced DNA lesions but may also cause qualitative changes. If the different types of DNA lesions have different contributions to lethality, the OER for cell survival may represent a complex composite of these changes at the molecular level

CXCR3-dependent microglial recruitment is essential for dendrite loss after brain lesion

NARCIS (Netherlands)

Rappert, A; Bechmann, [No Value; Pivneva, T; Mahlo, J; Biber, K; Nolte, C; Kovac, AD; Gerard, C; Boddeke, HWGM; Nitsch, R; Kettenmann, H

2004-01-01

Microglia are the resident macrophage population of the CNS and are considered its major immunocompetent elements. They are activated by any type of brain pathology and can migrate to the lesion site. The chemokine CXCL10 is expressed in neurons in response to brain injury and is a signaling

Spinal motoneuron synaptic plasticity after axotomy in the absence of inducible nitric oxide synthase

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Zanon Renata G

2010-05-01

Full Text Available Abstract Background Astrocytes play a major role in preserving and restoring structural and physiological integrity following injury to the nervous system. After peripheral axotomy, reactive gliosis propagates within adjacent spinal segments, influenced by the local synthesis of nitric oxide (NO. The present work investigated the importance of inducible nitric oxide synthase (iNOS activity in acute and late glial responses after injury and in major histocompatibility complex class I (MHC I expression and synaptic plasticity of inputs to lesioned alpha motoneurons. Methods In vivo analyses were carried out using C57BL/6J-iNOS knockout (iNOS-/- and C57BL/6J mice. Glial response after axotomy, glial MHC I expression, and the effects of axotomy on synaptic contacts were measured using immunohistochemistry and transmission electron microscopy. For this purpose, 2-month-old animals were sacrificed and fixed one or two weeks after unilateral sciatic nerve transection, and spinal cord sections were incubated with antibodies against classical MHC I, GFAP (glial fibrillary acidic protein - an astroglial marker, Iba-1 (an ionized calcium binding adaptor protein and a microglial marker or synaptophysin (a presynaptic terminal marker. Western blotting analysis of MHC I and nNOS expression one week after lesion were also performed. The data were analyzed using a two-tailed Student's t test for parametric data or a two-tailed Mann-Whitney U test for nonparametric data. Results A statistical difference was shown with respect to astrogliosis between strains at the different time points studied. Also, MHC I expression by iNOS-/- microglial cells did not increase at one or two weeks after unilateral axotomy. There was a difference in synaptophysin expression reflecting synaptic elimination, in which iNOS-/- mice displayed a decreased number of the inputs to alpha motoneurons, in comparison to that of C57BL/6J. Conclusion The findings herein indicate that i

Axonal regeneration and development of de novo axons from distal dendrites of adult feline commissural interneurons after a proximal axotomy

DEFF Research Database (Denmark)

Fenrich, Keith K; Skelton, Nicole; MacDermid, Victoria E

2007-01-01

Following proximal axotomy, several types of neurons sprout de novo axons from distal dendrites. These processes may represent a means of forming new circuits following spinal cord injury. However, it is not know whether mammalian spinal interneurons, axotomized as a result of a spinal cord injury......, develop de novo axons. Our goal was to determine whether spinal commissural interneurons (CINs), axotomized by 3-4-mm midsagittal transection at C3, form de novo axons from distal dendrites. All experiments were performed on adult cats. CINs in C3 were stained with extracellular injections of Neurobiotin...... at 4-5 weeks post injury. The somata of axotomized CINs were identified by the presence of immunoreactivity for the axonal growth-associated protein-43 (GAP-43). Nearly half of the CINs had de novo axons that emerged from distal dendrites. These axons lacked immunoreactivity for the dendritic protein...

MRI of peripheral nerve lesions of the lower limbs

Energy Technology Data Exchange (ETDEWEB)

Lacour-Petit, M.C.; Ducreux, D. [Dept. of Neuroradiology, Hopital Bicetre, Kremlin-Bicetre (France); Lozeron, P. [Dept. of Neurology, Hopital Bicetre, Kremlin-Bicetre (France)

2003-03-01

Our aim is to illustrate the contribution of MRI to diagnosis of lesions of the lower-limb nerve trunks. We report six patients who had clinical and electrophysiological examination for a peroneal or tibial nerve palsy. MRI of the knee showed in three cases a nonenhancing cystic lesion of the peroneal nerve suggesting an intraneural ganglion cyst, confirmed by histological study in one case. One patient with known neurofibromatosis had an enhancing nodular lesion of the peroneal nerve compatible with a neurofibroma. Two patients had diffuse hypertrophy with high signal on T2-weighted images, without contrast enhancement of the sciatic nerve or its branches. These lesions were compatible with localised hypertrophic neuropathy. In one case, biopsy of the superficial branch of the peroneal nerve showed insignificant axonal degeneration. MRI can provide information about the size and site of the abnormal segment of a nerve before treatment and can be used to distinguish different patterns of focal lesion. (orig.)

Targeting Microglial KATP Channels to Treat Neurodegenerative Diseases: A Mitochondrial Issue

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Manuel J. Rodríguez

2013-01-01

Full Text Available Neurodegeneration is a complex process involving different cell types and neurotransmitters. A common characteristic of neurodegenerative disorders is the occurrence of a neuroinflammatory reaction in which cellular processes involving glial cells, mainly microglia and astrocytes, are activated in response to neuronal death. Microglia do not constitute a unique cell population but rather present a range of phenotypes closely related to the evolution of neurodegeneration. In a dynamic equilibrium with the lesion microenvironment, microglia phenotypes cover from a proinflammatory activation state to a neurotrophic one directly involved in cell repair and extracellular matrix remodeling. At each moment, the microglial phenotype is likely to depend on the diversity of signals from the environment and of its response capacity. As a consequence, microglia present a high energy demand, for which the mitochondria activity determines the microglia participation in the neurodegenerative process. As such, modulation of microglia activity by controlling microglia mitochondrial activity constitutes an innovative approach to interfere in the neurodegenerative process. In this review, we discuss the mitochondrial KATP channel as a new target to control microglia activity, avoid its toxic phenotype, and facilitate a positive disease outcome.

Modeling of axonal endoplasmic reticulum network by spastic paraplegia proteins.

Science.gov (United States)

Yalçın, Belgin; Zhao, Lu; Stofanko, Martin; O'Sullivan, Niamh C; Kang, Zi Han; Roost, Annika; Thomas, Matthew R; Zaessinger, Sophie; Blard, Olivier; Patto, Alex L; Sohail, Anood; Baena, Valentina; Terasaki, Mark; O'Kane, Cahir J

2017-07-25

Axons contain a smooth tubular endoplasmic reticulum (ER) network that is thought to be continuous with ER throughout the neuron; the mechanisms that form this axonal network are unknown. Mutations affecting reticulon or REEP proteins, with intramembrane hairpin domains that model ER membranes, cause an axon degenerative disease, hereditary spastic paraplegia (HSP). We show that Drosophila axons have a dynamic axonal ER network, which these proteins help to model. Loss of HSP hairpin proteins causes ER sheet expansion, partial loss of ER from distal motor axons, and occasional discontinuities in axonal ER. Ultrastructural analysis reveals an extensive ER network in axons, which shows larger and fewer tubules in larvae that lack reticulon and REEP proteins, consistent with loss of membrane curvature. Therefore HSP hairpin-containing proteins are required for shaping and continuity of axonal ER, thus suggesting roles for ER modeling in axon maintenance and function.

Endodontic periapical lesion-induced mental nerve paresthesia

Science.gov (United States)

Shadmehr, Elham; Shekarchizade, Neda

2015-01-01

Paresthesia is a burning or prickling sensation or partial numbness, resulting from neural injury. The symptoms can vary from mild neurosensory dysfunction to total loss of sensation in the innervated area. Only a few cases have described apical periodontitis to be the etiological factor of impaired sensation in the area innervated by the inferior alveolar and mental nerves. The aim of the present paper is to report a case of periapical lesion-induced paresthesia in the innervation area of the mental nerve, which was successfully treated with endodontic retreatment. PMID:25878687

Schwann Cell Glycogen Selectively Supports Myelinated Axon Function

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Brown, Angus M; Evans, Richard D; Black, Joel; Ransom, Bruce R

2012-01-01

Objectives Interruption of energy supply to peripheral axons is a cause of axon loss. We determined if glycogen was present in mammalian peripheral nerve, and if it supported axon conduction during aglycemia. Methods We used biochemical assay and electron microscopy to determine the presence of glycogen, and electrophysiology to monitor axon function. Results Glycogen was present in sciatic nerve, its concentration varying directly with ambient [glucose]. Electron microscopy detected glycogen granules primarily in myelinating Schwann cell cytoplasm and these diminished after exposure to aglycemia. During aglycemia, conduction failure in large myelinated axons (A fibers) mirrored the time-course of glycogen loss. Latency to CAP failure was directly related to nerve glycogen content at aglycemia onset. Glycogen did not benefit the function of slow-conducting, small diameter unmyelinated axons (C fibers) during aglycemia. Blocking glycogen breakdown pharmacologically accelerated CAP failure during aglycemia in A fibers, but not in C fibers. Lactate was as effective as glucose in supporting sciatic nerve function, and was continuously released into the extracellular space in the presence of glucose and fell rapidly during aglycemia. Interpretation Our findings indicated that glycogen is present in peripheral nerve, primarily in myelinating Schwann cells, and exclusively supports large diameter, myelinated axon conduction during aglycemia. Available evidence suggests that peripheral nerve glycogen breaks down during aglycemia and is passed, probably as lactate, to myelinated axons to support function. Unmyelinated axons are not protected by glycogen and are more vulnerable to dysfunction during periods of hypoglycemia. PMID:23034913

Ammonium-induced impairment of axonal growth is prevented through glial creatine.

OpenAIRE

Braissant, O.; Henry, H.; Villard, A.M.; Zurich, M.G.; Loup, M.; Eilers, B.; Parlascino, G.; Matter, E.; Boulat, O.; Honegger, P.; Bachmann, C.

2002-01-01

Hyperammonemia in neonates and infants affects brain development and causes mental retardation. We report that ammonium impaired cholinergic axonal growth and altered localization and phosphorylation of intermediate neurofilament protein in rat reaggregated brain cell primary cultures. This effect was restricted to the phase of early maturation but did not occur after synaptogenesis. Exposure to NH4Cl decreased intracellular creatine, phosphocreatine, and ADP. We demonstrate that creatine cot...

Optical Coherence Tomography-A New Diagnostic Tool to Evaluate Axonal Degeneration in Multiple Sclerosis: A Review

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Nilüfer Kale

2010-09-01

Full Text Available Multiple sclerosis is an inflammatory demyelinating disorder of the central nervous system with a wide spectrum of clinical signs and symptoms. Multiple sclerosis lesions have a predilection for the optic nerves, periventricular white matter, brainstem, spinal cord, and cerebellum. The mechanisms responsible for multiple sclerosis are complex and heterogeneous across patients and disease stages. No specific markers exist for the definite diagnosis and prognosis of multiple sclerosis. The afferent visual pathway, which extends from the retina to the primary visual cortex including the optic nerve, is one of the most commonly affected sites in multiple sclerosis (94-99%. Pathology of affected optic nerves exhibits inflammation, demyelination, gliosis, axonal injury, and thinning of the retinal nerve fiber layer (RNFL. The RNFL is composed of unmyelinated axons, and measuring RNFL thickness is a viable method to monitor axonal loss reflecting disease progression. Optical coherence tomography is a noninvasive and reproducible tool in assessing the impact of multiple sclerosis on the thickness of the RNFL. Assessment of the afferent visual pathway using clinical, imaging and electrophysiological methods provides insights into the pathophysiology of multiple sclerosis and may also serve a prognostic role in multiple sclerosis

Cannabinoid receptor CB2 modulates axon guidance

DEFF Research Database (Denmark)

Duff, Gabriel; Argaw, Anteneh; Cecyre, Bruno

2013-01-01

on axon guidance. These effects are specific to CB2R since no changes were observed in mice where the gene coding for this receptor was altered (cnr2 (-/-)). The CB2R induced morphological changes observed at the growth cone are PKA dependent and require the presence of the netrin-1 receptor, Deleted...... CB2R's implication in retinothalamic development. Overall, this study demonstrates that the contribution of endocannabinoids to brain development is not solely mediated by CB1R, but also involves CB2R....

Data from SILAC-based quantitative analysis of lysates from mouse microglial cells treated with Withaferin A (WA).

Science.gov (United States)

Narayan, Malathi; Seeley, Kent W; Jinwal, Umesh K

2016-06-01

Mass spectrometry data collected in a study analyzing the effect of withaferin A (WA) on a mouse microglial (N9) cell line is presented in this article. Data was collected from SILAC-based quantitative analysis of lysates from mouse microglial cells treated with either WA or DMSO vehicle control. This article reports all the proteins that were identified in this analysis. The data presented here is related to the published research article on the effect of WA on the differential regulation of proteins in mouse microglial cells [1]. Mass spectrometry data has also been deposited in the ProteomeXchange with the identifier PXD003032.

Death Receptor 6 Promotes Wallerian Degeneration in Peripheral Axons.

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Gamage, Kanchana K; Cheng, Irene; Park, Rachel E; Karim, Mardeen S; Edamura, Kazusa; Hughes, Christopher; Spano, Anthony J; Erisir, Alev; Deppmann, Christopher D

2017-03-20

Axon degeneration during development is required to sculpt a functional nervous system and is also a hallmark of pathological insult, such as injury [1, 2]. Despite similar morphological characteristics, very little overlap in molecular mechanisms has been reported between pathological and developmental degeneration [3-5]. In the peripheral nervous system (PNS), developmental axon pruning relies on receptor-mediated extrinsic degeneration mechanisms to determine which axons are maintained or degenerated [5-7]. Receptors have not been implicated in Wallerian axon degeneration; instead, axon autonomous, intrinsic mechanisms are thought to be the primary driver for this type of axon disintegration [8-10]. Here we survey the role of neuronally expressed, paralogous tumor necrosis factor receptor super family (TNFRSF) members in Wallerian degeneration. We find that an orphan receptor, death receptor 6 (DR6), is required to drive axon degeneration after axotomy in sympathetic and sensory neurons cultured in microfluidic devices. We sought to validate these in vitro findings in vivo using a transected sciatic nerve model. Consistent with the in vitro findings, DR6 -/- animals displayed preserved axons up to 4 weeks after injury. In contrast to phenotypes observed in Wld s and Sarm1 -/- mice, preserved axons in DR6 -/- animals display profound myelin remodeling. This indicates that deterioration of axons and myelin after axotomy are mechanistically distinct processes. Finally, we find that JNK signaling after injury requires DR6, suggesting a link between this novel extrinsic pathway and the axon autonomous, intrinsic pathways that have become established for Wallerian degeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

A γ-secretase inhibitor, but not a γ-secretase modulator, induced defects in BDNF axonal trafficking and signaling: evidence for a role for APP.

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April M Weissmiller

Full Text Available Clues to Alzheimer disease (AD pathogenesis come from a variety of different sources including studies of clinical and neuropathological features, biomarkers, genomics and animal and cellular models. An important role for amyloid precursor protein (APP and its processing has emerged and considerable interest has been directed at the hypothesis that Aβ peptides induce changes central to pathogenesis. Accordingly, molecules that reduce the levels of Aβ peptides have been discovered such as γ-secretase inhibitors (GSIs and modulators (GSMs. GSIs and GSMs reduce Aβ levels through very different mechanisms. However, GSIs, but not GSMs, markedly increase the levels of APP CTFs that are increasingly viewed as disrupting neuronal function. Here, we evaluated the effects of GSIs and GSMs on a number of neuronal phenotypes possibly relevant to their use in treatment of AD. We report that GSI disrupted retrograde axonal trafficking of brain-derived neurotrophic factor (BDNF, suppressed BDNF-induced downstream signaling pathways and induced changes in the distribution within neuronal processes of mitochondria and synaptic vesicles. In contrast, treatment with a novel class of GSMs had no significant effect on these measures. Since knockdown of APP by specific siRNA prevented GSI-induced changes in BDNF axonal trafficking and signaling, we concluded that GSI effects on APP processing were responsible, at least in part, for BDNF trafficking and signaling deficits. Our findings argue that with respect to anti-amyloid treatments, even an APP-specific GSI may have deleterious effects and GSMs may serve as a better alternative.

Delayed xenon post-conditioning mitigates spinal cord ischemia/reperfusion injury in rabbits by regulating microglial activation and inflammatory factors.

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Yang, Yan-Wei; Wang, Yun-Lu; Lu, Jia-Kai; Tian, Lei; Jin, Mu; Cheng, Wei-Ping

2018-03-01

The neuroprotective effect against spinal cord ischemia/reperfusion injury in rats exerted by delayed xenon post-conditioning is stronger than that produced by immediate xenon post-conditioning. However, the mechanisms underlying this process remain unclear. Activated microglia are the main inflammatory cell type in the nervous system. The release of pro-inflammatory factors following microglial activation can lead to spinal cord damage, and inhibition of microglial activation can relieve spinal cord ischemia/reperfusion injury. To investigate how xenon regulates microglial activation and the release of inflammatory factors, a rabbit model of spinal cord ischemia/reperfusion injury was induced by balloon occlusion of the infrarenal aorta. After establishment of the model, two interventions were given: (1) immediate xenon post-conditioning-after reperfusion, inhalation of 50% xenon for 1 hour, 50% N 2 /50%O 2 for 2 hours; (2) delayed xenon post-conditioning-after reperfusion, inhalation of 50% N 2 /50%O 2 for 2 hours, 50% xenon for 1 hour. At 4, 8, 24, 48 and 72 hours after reperfusion, hindlimb locomotor function was scored using the Jacobs locomotor scale. At 72 hours after reperfusion, interleukin 6 and interleukin 10 levels in the spinal cord of each group were measured using western blot assays. Iba1 levels were determined using immunohistochemistry and a western blot assay. The number of normal neurons at the injury site was quantified using hematoxylin-eosin staining. At 72 hours after reperfusion, delayed xenon post-conditioning remarkably enhanced hindlimb motor function, increased the number of normal neurons at the injury site, decreased Iba1 levels, and inhibited interleukin-6 and interleukin-10 levels in the spinal cord. Immediate xenon post-conditioning did not noticeably affect the above-mentioned indexes. These findings indicate that delayed xenon post-conditioning after spinal cord injury improves the recovery of neurological function by reducing

Astroglia-Microglia Cross Talk during Neurodegeneration in the Rat Hippocampus

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Montserrat Batlle

2015-01-01

Full Text Available Brain injury triggers a progressive inflammatory response supported by a dynamic astroglia-microglia interplay. We investigated the progressive chronic features of the astroglia-microglia cross talk in the perspective of neuronal effects in a rat model of hippocampal excitotoxic injury. N-Methyl-D-aspartate (NMDA injection triggered a process characterized within 38 days by atrophy, neuronal loss, and fast astroglia-mediated S100B increase. Microglia reaction varied with the lesion progression. It presented a peak of tumor necrosis factor-α (TNF-α secretion at one day after the lesion, and a transient YM1 secretion within the first three days. Microglial glucocorticoid receptor expression increased up to day 5, before returning progressively to sham values. To further investigate the astroglia role in the microglia reaction, we performed concomitant transient astroglia ablation with L-α-aminoadipate and NMDA-induced lesion. We observed a striking maintenance of neuronal death associated with enhanced microglial reaction and proliferation, increased YM1 concentration, and decreased TNF-α secretion and glucocorticoid receptor expression. S100B reactivity only increased after astroglia recovery. Our results argue for an initial neuroprotective microglial reaction, with a direct astroglial control of the microglial cytotoxic response. We propose the recovery of the astroglia-microglia cross talk as a tissue priority conducted to ensure a proper cellular coordination that retails brain damage.

Astroglia-Microglia Cross Talk during Neurodegeneration in the Rat Hippocampus

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Batlle, Montserrat; Ferri, Lorenzo; Andrade, Carmen; Ortega, Francisco-Javier; Vidal-Taboada, Jose M.; Pugliese, Marco; Mahy, Nicole; Rodríguez, Manuel J.

2015-01-01

Brain injury triggers a progressive inflammatory response supported by a dynamic astroglia-microglia interplay. We investigated the progressive chronic features of the astroglia-microglia cross talk in the perspective of neuronal effects in a rat model of hippocampal excitotoxic injury. N-Methyl-D-aspartate (NMDA) injection triggered a process characterized within 38 days by atrophy, neuronal loss, and fast astroglia-mediated S100B increase. Microglia reaction varied with the lesion progression. It presented a peak of tumor necrosis factor-α (TNF-α) secretion at one day after the lesion, and a transient YM1 secretion within the first three days. Microglial glucocorticoid receptor expression increased up to day 5, before returning progressively to sham values. To further investigate the astroglia role in the microglia reaction, we performed concomitant transient astroglia ablation with L-α-aminoadipate and NMDA-induced lesion. We observed a striking maintenance of neuronal death associated with enhanced microglial reaction and proliferation, increased YM1 concentration, and decreased TNF-α secretion and glucocorticoid receptor expression. S100B reactivity only increased after astroglia recovery. Our results argue for an initial neuroprotective microglial reaction, with a direct astroglial control of the microglial cytotoxic response. We propose the recovery of the astroglia-microglia cross talk as a tissue priority conducted to ensure a proper cellular coordination that retails brain damage. PMID:25977914

Transplantation of hamster lung lesions induced by 239PuO2 or benz(a)pyrene

International Nuclear Information System (INIS)

McDonald, K.E.; Sanders, C.L.

1980-01-01

None(0%) of 1000 recipients of lung lesions for 239 PuO 2 -exposed hamsters that were transplanted into other hamsters' cheek pouches, developed tumors, whereas 90% of transplants from benz(a)pyrene-induced lung lesions were malignant

Electrophysiology of Axonal Constrictions

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Johnson, Christopher; Jung, Peter; Brown, Anthony

2013-03-01

Axons of myelinated neurons are constricted at the nodes of Ranvier, where they are directly exposed to the extracellular space and where the vast majority of the ion channels are located. These constrictions are generated by local regulation of the kinetics of neurofilaments the most important cytoskeletal elements of the axon. In this paper we discuss how this shape affects the electrophysiological function of the neuron. Specifically, although the nodes are short (about 1 μm) in comparison to the distance between nodes (hundreds of μm) they have a substantial influence on the conduction velocity of neurons. We show through computational modeling that nodal constrictions (all other features such as numbers of ion channels left constant) reduce the required fiber diameter for a given target conduction velocity by up to 50% in comparison to an unconstricted axon. We further show that the predicted optimal fiber morphologies closely match reported fiber morphologies. Supported by The National Science Foundation (IOS 1146789)

Combination therapies in adjuvant with topical ALA-mediated photodynamic therapy for DMBA-induced hamster buccal pouch premalignant lesions

Science.gov (United States)

Yang, Deng-Fu; Hsu, Yih-Chih

2012-03-01

In Taiwan, oral cancer has becomes the fastest growth male cancer disease due to the betel nut chewing habit combing with smoking and alcohol-drinking lifestyle of people. In order to eliminate the systemic phototoxic effect of 5-aminolevulinic acid (ALA), this study was designed to use a topical ALA-mediated PDT for treatment of DMBA-induced hamster buccal pouch precancerous lesions. DMBA was applied to one of the buccal pouches of hamsters thrice a week for 10 to 12 weeks. Cancerous lesions were induced and proven by histological examination. These DMBA-induced cancerous lesions were used for testing the efficacy of topical ALA-mediated PDT. Before PDT, fluorescence spectroscopy was used to determine when ALA reached its peak level in the lesional epithelial cells after topical application of ALA gel. We found that ALA reached its peak level in precancerous lesions about 2.5 hrs after topical application of ALA gel. The cancerous lesions in hamsters were then treated with topical ALA -mediated PDT with light exposure dose of 150 J/cm2 using LED 635 nm fiber-guided light device. Visual examination demonstrated that adjuvant topical ALA -mediated PDT group has shown better therapeutic results in compared to those of non-adjuvant topical ALA-mediated PDT group for DMBA-induced hamster buccal pouch precancerous lesions.

Involvement of PKA and HO-1 signaling in anti-inflammatory effects of surfactin in BV-2 microglial cells

Energy Technology Data Exchange (ETDEWEB)

Park, Sun Young; Kim, Ji-Hee [Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735 (Korea, Republic of); Lee, Sang Joon [Department of Microbiology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735 (Korea, Republic of); Kim, YoungHee, E-mail: yheekim@pusan.ac.kr [Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735 (Korea, Republic of)

2013-04-01

Surfactin, one of the most powerful biosurfactants, is a bacterial cyclic lipopeptide. Here, we investigated the anti-neuroinflammatory properties of surfactin in lipoteichoic acid (LTA)-stimulated BV-2 microglial cells. Surfactin significantly inhibited excessive production of the pro-inflammatory mediators TNF-α, IL-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), prostaglandin E{sub 2} (PGE{sub 2}), nitric oxide (NO) and reactive oxygen species (ROS), and suppressed the expression of matrix metalloproteinase-9 (MMP-9), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). Subsequent mechanistic studies revealed that surfactin inhibited LTA-induced nuclear factor-kappaB (NF-κB) and signal transducer and activator of transcription-1 (STAT-1) activation. However, surfactin increases the phosphorylation of the STAT-3, a component of the homeostatic mechanism causing anti-inflammatory events. We also demonstrated that surfactin induces heme oxygenase-1 (HO-1) expression and nuclear factor-regulated factor-2 (Nrf-2) activation, and that the anti-inflammatory effects of surfactin are abrogated by small interfering RNA-mediated knock-down of HO-1 or Nrf-2. Interestingly, we found that surfactin increased the level of cAMP and induced phosphorylation of cAMP responsive element binding protein (CREB) in microglial cells. Furthermore, treatment with the protein kinase A (PKA) inhibitor, H-89, blocked HO-1 induction by surfactin and abolished surfactin's suppressive effects on ROS and NO production. These results indicate that HO-1 and its upstream effector, PKA, play a pivotal role in the anti-neuroinflammatory response of surfactin in LTA-stimulated microglia. Therefore, surfactin might have therapeutic potential for neuroprotective agents to treat inflammatory and neurodegenerative diseases. - Highlights: ► Surfactin inhibits proinflammatory mediator synthesis in LTA-activated BV-2 cells. ► Surfactin suppresses NF-κB and STAT-1, but potentiates

Involvement of PKA and HO-1 signaling in anti-inflammatory effects of surfactin in BV-2 microglial cells

International Nuclear Information System (INIS)

Park, Sun Young; Kim, Ji-Hee; Lee, Sang Joon; Kim, YoungHee

2013-01-01

Surfactin, one of the most powerful biosurfactants, is a bacterial cyclic lipopeptide. Here, we investigated the anti-neuroinflammatory properties of surfactin in lipoteichoic acid (LTA)-stimulated BV-2 microglial cells. Surfactin significantly inhibited excessive production of the pro-inflammatory mediators TNF-α, IL-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), prostaglandin E 2 (PGE 2 ), nitric oxide (NO) and reactive oxygen species (ROS), and suppressed the expression of matrix metalloproteinase-9 (MMP-9), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). Subsequent mechanistic studies revealed that surfactin inhibited LTA-induced nuclear factor-kappaB (NF-κB) and signal transducer and activator of transcription-1 (STAT-1) activation. However, surfactin increases the phosphorylation of the STAT-3, a component of the homeostatic mechanism causing anti-inflammatory events. We also demonstrated that surfactin induces heme oxygenase-1 (HO-1) expression and nuclear factor-regulated factor-2 (Nrf-2) activation, and that the anti-inflammatory effects of surfactin are abrogated by small interfering RNA-mediated knock-down of HO-1 or Nrf-2. Interestingly, we found that surfactin increased the level of cAMP and induced phosphorylation of cAMP responsive element binding protein (CREB) in microglial cells. Furthermore, treatment with the protein kinase A (PKA) inhibitor, H-89, blocked HO-1 induction by surfactin and abolished surfactin's suppressive effects on ROS and NO production. These results indicate that HO-1 and its upstream effector, PKA, play a pivotal role in the anti-neuroinflammatory response of surfactin in LTA-stimulated microglia. Therefore, surfactin might have therapeutic potential for neuroprotective agents to treat inflammatory and neurodegenerative diseases. - Highlights: ► Surfactin inhibits proinflammatory mediator synthesis in LTA-activated BV-2 cells. ► Surfactin suppresses NF-κB and STAT-1, but potentiates phosphorylation

Oxidative stress and proinflammatory cytokines contribute to demyelination and axonal damage in a cerebellar culture model of neuroinflammation.

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di Penta, Alessandra; Moreno, Beatriz; Reix, Stephanie; Fernandez-Diez, Begoña; Villanueva, Maite; Errea, Oihana; Escala, Nagore; Vandenbroeck, Koen; Comella, Joan X; Villoslada, Pablo

2013-01-01

Demyelination and axonal damage are critical processes in the pathogenesis of multiple sclerosis (MS). Oxidative stress and pro-inflammatory cytokines elicited by inflammation mediates tissue damage. To monitor the demyelination and axonal injury associated with microglia activation we employed a model using cerebellar organotypic cultures stimulated with lipopolysaccharide (LPS). Microglia activated by LPS released pro-inflammatory cytokines (IL-1β, IL-6 and TNFα), and increased the expression of inducible nitric oxide synthase (iNOS) and production of reactive oxygen species (ROS). This activation was associated with demyelination and axonal damage in cerebellar cultures. Axonal damage, as revealed by the presence of non-phosphorylated neurofilaments, mitochondrial accumulation in axonal spheroids, and axonal transection, was associated with stronger iNOS expression and concomitant increases in ROS. Moreover, we analyzed the contribution of pro-inflammatory cytokines and oxidative stress in demyelination and axonal degeneration using the iNOS inhibitor ethyl pyruvate, a free-scavenger and xanthine oxidase inhibitor allopurinol, as well as via blockage of pro-inflammatory cytokines using a Fc-TNFR1 construct. We found that blocking microglia activation with ethyl pyruvate or allopurinol significantly decreased axonal damage, and to a lesser extent, demyelination. Blocking TNFα significantly decreased demyelination but did not prevented axonal damage. Moreover, the most common therapy for MS, interferon-beta, was used as an example of an immunomodulator compound that can be tested in this model. In vitro, interferon-beta treatment decreased oxidative stress (iNOS and ROS levels) and the release of pro-inflammatory cytokines after LPS stimulation, reducing axonal damage. The model of neuroinflammation using cerebellar culture stimulated with endotoxin mimicked myelin and axonal damage mediated by the combination of oxidative stress and pro-inflammatory cytokines

Data from SILAC-based quantitative analysis of lysates from mouse microglial cells treated with Withaferin A (WA

Directory of Open Access Journals (Sweden)

Malathi Narayan

2016-06-01

Full Text Available Mass spectrometry data collected in a study analyzing the effect of withaferin A (WA on a mouse microglial (N9 cell line is presented in this article. Data was collected from SILAC-based quantitative analysis of lysates from mouse microglial cells treated with either WA or DMSO vehicle control. This article reports all the proteins that were identified in this analysis. The data presented here is related to the published research article on the effect of WA on the differential regulation of proteins in mouse microglial cells [1]. Mass spectrometry data has also been deposited in the ProteomeXchange with the identifier http://www.ebi.ac.uk/pride/archive/projects/PXD003032.

Internodal function in normal and regenerated mammalian axons

DEFF Research Database (Denmark)

Moldovan, M; Krarup, C

2007-01-01

AIM: Following Wallerian degeneration, peripheral myelinated axons have the ability to regenerate and, given a proper pathway, establish functional connections with targets. In spite of this capacity, the clinical outcome of nerve regeneration remains unsatisfactory. Early studies have found...... that regenerated internodes remain persistently short though this abnormality did not seem to influence recovery in conduction. It remains unclear to which extent abnormalities in axonal function itself may contribute to the poor outcome of nerve regeneration. METHODS: We review experimental evidence indicating...... that internodes play an active role in axonal function. RESULTS: By investigating internodal contribution to axonal excitability we have found evidence that axonal function may be permanently compromised in regenerated nerves. Furthermore, we illustrate that internodal function is also abnormal in regenerated...

Relationships between selective neuronal loss and microglial activation after ischaemic stroke in man.

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Morris, Rhiannon S; Simon Jones, P; Alawneh, Josef A; Hong, Young T; Fryer, Tim D; Aigbirhio, Franklin I; Warburton, Elizabeth A; Baron, Jean-Claude

2018-05-09

Modern ischaemic stroke management involves intravenous thrombolysis followed by mechanical thrombectomy, which allows markedly higher rates of recanalization and penumbral salvage than thrombolysis alone. However, <50% of treated patients eventually enjoy independent life. It is therefore important to identify complementary therapeutic targets. In rodent models, the salvaged penumbra is consistently affected by selective neuronal loss, which may hinder recovery by interfering with plastic processes, as well as by microglial activation, which may exacerbate neuronal death. However, whether the salvaged penumbra in man is similarly affected is still unclear. Here we determined whether these two processes affect the non-infarcted penumbra in man and, if so, whether they are inter-related. We prospectively recruited patients with (i) acute middle-cerebral artery stroke; (ii) penumbra present on CT perfusion obtained <4.5 h of stroke onset; and (iii) early neurological recovery as a marker of penumbral salvage. PET with 11C-flumazenil and 11C-PK11195, as well as MRI to map the final infarct, were obtained at predefined follow-up times. The presence of selective neuronal loss and microglial activation was determined voxel-wise within the MRI normal-appearing ipsilateral non-infarcted zone and surviving penumbra masks, and their inter-relationship was assessed both across and within patients. Dilated infarct contours were consistently excluded to control for partial volume effects. Across the 16 recruited patients, there was reduced 11C-flumazenil and increased 11C-PK11195 binding in the whole ipsilateral non-infarcted zone (P = 0.04 and 0.02, respectively). Within the non-infarcted penumbra, 11C-flumazenil was also reduced (P = 0.001), but without clear increase in 11C-PK11195 (P = 0.18). There was no significant correlation between 11C-flumazenil and 11C-PK11195 in either compartment. This mechanistic study provides direct evidence for the presence of both neuronal

Studies in the development of a bridging device for guiding regenerating axons

Science.gov (United States)

Wen, Xuejun

At present there is no clinically effective treatment for injuries or pathological processes that disrupt the continuity of axons in the mature central nervous system. However, a number of studies suggest that a tremendous potential exists for developing therapies. In particular biomaterials in the form of bridging substrates been shown to support at least some level of axonal regeneration across the lesion site, but display a limited capacity for directing axons toward their targets. To influence the directionality of the regeneration process filaments and tubes appear promising but the technology is far from optimized. As a step toward optimization, we investigated various components of a tissue-engineered bridging device consisting of numerous filaments surrounded by a semipermeable biodegradable hollow fiber membrane (HFM). In the first part of the thesis, we studied the influence of filament diameter and various extracellular matrix coatings on neuron regeneration suing a dorsal root ganglion explant model. We found that laminin surface treated filaments that approached the size of spinal axons support significantly longer regenerative outgrowth than similarly treated filaments of larger diameter, and exceed outgrowth distance on similarly sized filaments treated with fibronectin. Such substrates also consistently supported the attachment and alignment of glial cells and directed the outgrowth of regenerating axons along the long axis of the filaments. In the last part of the thesis, biodegradable hollow fiber membranes were fabricated and their physical, chemical and degradation properties were analyzed. We found that it is possible to use phase inversion methods to fabricate hollow fiber membranes of widely varying properties that degrade of the course of several months. We then evaluated the biocompatibility of the new materials after implantation in the CNS using an adult rat model. We found that the implants were well tolerated and elicited a reaction

Optofluidic control of axonal guidance

Science.gov (United States)

Gu, Ling; Ordonez, Simon; Black, Bryan; Mohanty, Samarendra K.

2013-03-01

Significant efforts are being made for control on axonal guidance due to its importance in nerve regeneration and in the formation of functional neuronal circuitry in-vitro. These include several physical (topographic modification, optical force, and electric field), chemical (surface functionalization cues) and hybrid (electro-chemical, photochemical etc) methods. Here, we report comparison of the effect of linear flow versus microfluidic flow produced by an opticallydriven micromotor in guiding retinal ganglion axons. A circularly polarized laser tweezers was used to hold, position and spin birefringent calcite particle near growth cone, which in turn resulted in microfluidic flow. The flow rate and resulting shear-force on axons could be controlled by a varying the power of the laser tweezers beam. The calcite particles were placed separately in one chamber and single particle was transported through microfluidic channel to another chamber containing the retina explant. In presence of flow, the turning of axons was found to strongly correlate with the direction of flow. Turning angle as high as 90° was achieved. Optofluidic-manipulation can be applied to other types of mammalian neurons and also can be extended to stimulate mechano-sensing neurons.

Can injured adult CNS axons regenerate by recapitulating development?

Science.gov (United States)

Hilton, Brett J; Bradke, Frank

2017-10-01

In the adult mammalian central nervous system (CNS), neurons typically fail to regenerate their axons after injury. During development, by contrast, neurons extend axons effectively. A variety of intracellular mechanisms mediate this difference, including changes in gene expression, the ability to form a growth cone, differences in mitochondrial function/axonal transport and the efficacy of synaptic transmission. In turn, these intracellular processes are linked to extracellular differences between the developing and adult CNS. During development, the extracellular environment directs axon growth and circuit formation. In adulthood, by contrast, extracellular factors, such as myelin and the extracellular matrix, restrict axon growth. Here, we discuss whether the reactivation of developmental processes can elicit axon regeneration in the injured CNS. © 2017. Published by The Company of Biologists Ltd.

Regulation of Adult CNS Axonal Regeneration by the Post-transcriptional Regulator Cpeb1

Directory of Open Access Journals (Sweden)

Wilson Pak-Kin Lou

2018-01-01

Full Text Available Adult mammalian central nervous system (CNS neurons are unable to regenerate following axonal injury, leading to permanent functional impairments. Yet, the reasons underlying this regeneration failure are not fully understood. Here, we studied the transcriptome and translatome shortly after spinal cord injury. Profiling of the total and ribosome-bound RNA in injured and naïve spinal cords identified a substantial post-transcriptional regulation of gene expression. In particular, transcripts associated with nervous system development were down-regulated in the total RNA fraction while remaining stably loaded onto ribosomes. Interestingly, motif association analysis of post-transcriptionally regulated transcripts identified the cytoplasmic polyadenylation element (CPE as enriched in a subset of these transcripts that was more resistant to injury-induced reduction at the transcriptome level. Modulation of these transcripts by overexpression of the CPE binding protein, Cpeb1, in mouse and Drosophila CNS neurons promoted axonal regeneration following injury. Our study uncovered a global evolutionarily conserved post-transcriptional mechanism enhancing regeneration of injured CNS axons.

A single-strand specific lesion drives MMS-induced hyper-mutability at a double-strand break in yeast.

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Yang, Yong; Gordenin, Dmitry A; Resnick, Michael A

2010-08-05

Localized hyper-mutability (LHM) can be important in evolution, immunity, and genetic diseases. We previously reported that single-strand DNA (ssDNA) can be an important source of damage-induced LHM in yeast. Here, we establish that the generation of LHM by methyl methanesulfonate (MMS) during repair of a chromosomal double-strand break (DSB) can result in over 0.2 mutations/kb, which is approximately 20,000-fold higher than the MMS-induced mutation density without a DSB. The MMS-induced mutations associated with DSB repair were primarily due to substitutions via translesion DNA synthesis at damaged cytosines, even though there are nearly 10 times more MMS-induced lesions at other bases. Based on this mutation bias, the promutagenic lesion dominating LHM is likely 3-methylcytosine, which is single-strand specific. Thus, the dramatic increase in mutagenesis at a DSB is concluded to result primarily from the generation of non-repairable lesions in ssDNA associated with DSB repair along with efficient induction of highly mutagenic ssDNA-specific lesions. These findings with MMS-induced LHM have broad biological implications for unrepaired damage generated in ssDNA and possibly ssRNA. Published by Elsevier B.V.

DNA radio-induced tandem lesions: formation, introduction in oligonucleotides and repair

International Nuclear Information System (INIS)

Bourdat, Anne-Gaelle

2000-01-01

Cell killing induced by excited photosensitizers, ionizing radiation or radiomimetic drugs can not be only explained by the formation of single DNA lesions. Thus, multiply damaged sites, are likely to have harmful biological consequences. One example of tandem base damage induced by ".OH radical in X-irradiated aqueous solution of DNA oligomers is N-(2-deoxy-β-D-erythro-pentofuranosyl)-formyl-amine (dβF)/8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). In order to investigate the biological significance of such a tandem lesion, both 8-oxodGuo and dβF were introduced in synthetic oligonucleotides at vicinal positions using the solid phase phosphoramidite method with the 'Pac phosphoramidite' chemistry. The purity of the synthetic DNA fragments and the integrity of modified nucleosides was confirmed using different complementary techniques: HPLC, PAGE, ESI MS, MALDI-TOF MS and capillary electrophoresis. Using the above synthetic substrates, investigations were carried out in order to determine the substrate specificity and the excision mechanism of three glycosylases involved in the base excision repair pathway: endonuclease III, Fpg and yOggl. Both tandem lesions were substrates for the BER enzymes. However, the tandem lesion are not completely excised by the repair enzymes. The rates of excision as inferred from the determination of the ratios of Vm/Km Michaelis kinetics constants were not found to be significantly affected by the presence of the tandem lesions. MALDI-TOF mass spectrometry was used in order to gain insights into mechanistic aspects of oligonucleotide cleavage by the BER enzymes. During in vitro DNA synthesis by Taq DNA polymerase, Klenow fragment exo- and DNA polymerase β, tandem base damage were found to block the progression of the enzymes. Finally, the level of tandem base damage in the DNA exposed to γ-ray using the liquid chromatography coupled to electro-spray ionization tandem mass spectrometry was determined. Both dβF-8-oxodGuo and 8

γ-diketone central neuropathy: quantitative morphometric analysis of axons in rat spinal cord white matter regions and nerve roots

International Nuclear Information System (INIS)

LoPachin, Richard M.; Jortner, Bernard S.; Reid, Maria L.; Das, Soma

2003-01-01

A quantitative analytical method was used to measure myelinated axon morphometric parameters (e.g., axon area, ratio of axon area/fiber area, and index of circularity) in rat nervous tissue during intoxication with 2,5-hexanedione (HD). Parameters were assessed in nerve roots (dorsal and ventral) and in ascending (gracile fasciculus and spinocerebellar tract) and descending (corticospinal and rubrospinal tracts) spinal cord white matter tracts (L4-L5) of rats intoxicated with HD at two different daily dose-rates (175 or 400 mg HD/kg/day, gavage). For each dose-rate, tissue was sampled at four neurological endpoints: unaffected, slight, moderate, and severe toxicity, as determined by gait analysis and measurements of grip strength. Results indicate that, regardless of the HD dose-rate, axon atrophy (reduced axon area) was a widespread, abundant effect that developed in concert with neurological deficits. The atrophy response occurred contemporaneously in both ascending and descending spinal tracts, which suggests that loss of caliber developed simultaneously along the proximodistal axon axis. In contrast, swollen axons were a numerically small component and were present in nerve roots and spinal tracts only during subchronic intoxication at the lower HD dose-rate (i.e., 175 mg/kg/day). Intoxication at the higher dose-rate (400 mg/kg/day) produced neurological deficits in the absence of axonal swellings. These observations in conjunction with our previous studies of HD-induced peripheral neuropathy (Toxicol. Appl. Pharmacol. 135 (1995) 58; and Toxicol. Appl. Pharmacol. 165 (2000) 127) indicate that axon atrophy, and not axonal swelling, is a primary neuropathic phenomenon

The protection of acetylcholinesterase inhibitor on β-amyloid-induced injury of neurite outgrowth via regulating axon guidance related genes expression in neuronal cells

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Shen, Jiao-Ning; Wang, Deng-Shun; Wang, Rui

2012-01-01

Cognitive deficits in AD correlate with progressive synaptic dysfunction and loss. The Rho family of small GTPases, including Rho, Rac, and Cdc42, has a central role in cellular motility and cytokinesis. Acetylcholinesterase inhibitor has been found to protect cells against a broad range of reagents-induced injuries. Present studies examined if the effect of HupA on neurite outgrowth in Aβ-treated neuronal cells executed via regulating Rho-GTPase mediated axon guidance relative gene expressio...

Histopathology of cryoballoon ablation-induced phrenic nerve injury.

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Andrade, Jason G; Dubuc, Marc; Ferreira, Jose; Guerra, Peter G; Landry, Evelyn; Coulombe, Nicolas; Rivard, Lena; Macle, Laurent; Thibault, Bernard; Talajic, Mario; Roy, Denis; Khairy, Paul

2014-02-01

Hemi-diaphragmatic paralysis is the most common complication associated with cryoballoon ablation for atrial fibrillation, yet the histopathology of phrenic nerve injury has not been well described. A preclinical randomized study was conducted to characterize the histopathology of phrenic nerve injury induced by cryoballoon ablation and assess the potential for electromyographic (EMG) monitoring to limit phrenic nerve damage. Thirty-two dogs underwent cryoballoon ablation of the right superior pulmonary vein with the objective of inducing phrenic nerve injury. Animals were randomized 1:1 to standard monitoring (i.e., interruption of ablation upon reduction in diaphragmatic motion) versus EMG guidance (i.e., cessation of ablation upon a 30% reduction in the diaphragmatic compound motor action potential [CMAP] amplitude). The acute procedural endpoint was achieved in all dogs. Phrenic nerve injury was characterized by Wallerian degeneration, with subperineural injury to large myelinated axons and evidence of axonal regeneration. The degree of phrenic nerve injury paralleled the reduction in CMAP amplitude (P = 0.007). Animals randomized to EMG guidance had a lower incidence of acute hemi-diaphragmatic paralysis (50% vs 100%; P = 0.001), persistent paralysis at 30 days (21% vs 75%; multivariate odds ratio 0.12, 95% confidence interval [0.02, 0.69], P = 0.017), and a lesser severity of histologic injury (P = 0.001). Mature pulmonary vein ablation lesion characteristics, including circumferentiality and transmurality, were similar in both groups. Phrenic nerve injury induced by cryoballoon ablation is axonal in nature and characterized by Wallerian degeneration, with potential for recovery. An EMG-guided approach is superior to standard monitoring in limiting phrenic nerve damage. © 2013 Wiley Periodicals, Inc.

The Absence of Sensory Axon Bifurcation Affects Nociception and Termination Fields of Afferents in the Spinal Cord

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Philip Tröster

2018-02-01

Full Text Available A cGMP signaling cascade composed of C-type natriuretic peptide, the guanylyl cyclase receptor Npr2 and cGMP-dependent protein kinase I (cGKI controls the bifurcation of sensory axons upon entering the spinal cord during embryonic development. However, the impact of axon bifurcation on sensory processing in adulthood remains poorly understood. To investigate the functional consequences of impaired axon bifurcation during adult stages we generated conditional mouse mutants of Npr2 and cGKI (Npr2fl/fl;Wnt1Cre and cGKIKO/fl;Wnt1Cre that lack sensory axon bifurcation in the absence of additional phenotypes observed in the global knockout mice. Cholera toxin labeling in digits of the hind paw demonstrated an altered shape of sensory neuron termination fields in the spinal cord of conditional Npr2 mouse mutants. Behavioral testing of both sexes indicated that noxious heat sensation and nociception induced by chemical irritants are impaired in the mutants, whereas responses to cold sensation, mechanical stimulation, and motor coordination are not affected. Recordings from C-fiber nociceptors in the hind limb skin showed that Npr2 function was not required to maintain normal heat sensitivity of peripheral nociceptors. Thus, the altered behavioral responses to noxious heat found in Npr2fl/fl;Wnt1Cre mice is not due to an impaired C-fiber function. Overall, these data point to a critical role of axonal bifurcation for the processing of pain induced by heat or chemical stimuli.

Protective Effects of α-Tocopherol, γ-Tocopherol and Oleic Acid, Three Compounds of Olive Oils, and No Effect of Trolox, on 7-Ketocholesterol-Induced Mitochondrial and Peroxisomal Dysfunction in Microglial BV-2 Cells

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Meryam Debbabi

2016-11-01

Full Text Available Lipid peroxidation products, such as 7-ketocholesterol (7KC, may be increased in the body fluids and tissues of patients with neurodegenerative diseases and trigger microglial dysfunction involved in neurodegeneration. It is therefore important to identify synthetic and natural molecules able to impair the toxic effects of 7KC. We determined the impact of 7KC on murine microglial BV-2 cells, especially its ability to trigger mitochondrial and peroxisomal dysfunction, and evaluated the protective effects of α- and γ-tocopherol, Trolox, and oleic acid (OA. Multiple complementary chemical assays, flow cytometric and biochemical methods were used to evaluate the antioxidant and cytoprotective properties of these molecules. According to various complementary assays to estimate antioxidant activity, only α-, and γ-tocopherol, and Trolox had antioxidant properties. However, only α-tocopherol, γ-tocopherol and OA were able to impair 7KC-induced loss of mitochondrial transmembrane potential, which is associated with increased permeability to propidium iodide, an indicator of cell death. In addition, α-and γ-tocopherol, and OA were able to prevent the decrease in Abcd3 protein levels, which allows the measurement of peroxisomal mass, and in mRNA levels of Abcd1 and Abcd2, which encode for two transporters involved in peroxisomal β-oxidation. Thus, 7KC-induced side effects are associated with mitochondrial and peroxisomal dysfunction which can be inversed by natural compounds, thus supporting the hypothesis that the composition of the diet can act on the function of organelles involved in neurodegenerative diseases.

Detection and repair of a UV-induced photosensitive lesion in the DNA of human cells

International Nuclear Information System (INIS)

Francis, A.A.; Regan, J.D.

1986-01-01

Irradiation with UV light results in damage to the DNA of human cells. The most numerous lesions are pyrimidine dimers; however, other lesions are known to occur and may contribute to the overall deleterious effect of UV irradiation. The authors have observed evidence of a UV-induced lesion other than pyrimidine dimers in the DNA of human cells by measuring DNA strand breaks induced by irradiating with 313-nm light following UV (254-nm) irradiation. The data suggest that, in normal cells, the lesion responsible for this effect is rapidly repaired or altered; whereas, in xeroderma pigmentosum variant cells it seems to remain unchanged. Some change apparently occurs in the DNA of xeroderma pigmentosum group A cells which results in an increase in photolability. These data indicate a deficiency in DNA repair of xeroderma pigmentosum variant cells as well as in xeroderma pigmentosum group A cells. (Auth.)

Peripheral Nerve Injuries and Transplantation of Olfactory Ensheathing Cells for Axonal Regeneration and Remyelination: Fact or Fiction?

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Christine Radtke

2012-10-01

Full Text Available Successful nerve regeneration after nerve trauma is not only important for the restoration of motor and sensory functions, but also to reduce the potential for abnormal sensory impulse generation that can occur following neuroma formation. Satisfying functional results after severe lesions are difficult to achieve and the development of interventional methods to achieve optimal functional recovery after peripheral nerve injury is of increasing clinical interest. Olfactory ensheathing cells (OECs have been used to improve axonal regeneration and functional outcome in a number of studies in spinal cord injury models. The rationale is that the OECs may provide trophic support and a permissive environment for axonal regeneration. The experimental transplantation of OECs to support and enhance peripheral nerve regeneration is much more limited. This chapter reviews studies using OECs as an experimental cell therapy to improve peripheral nerve regeneration.

Uncoupling nicotine mediated motoneuron axonal pathfinding errors and muscle degeneration in zebrafish

International Nuclear Information System (INIS)

Welsh, Lillian; Tanguay, Robert L.; Svoboda, Kurt R.

2009-01-01

Zebrafish embryos offer a unique opportunity to investigate the mechanisms by which nicotine exposure impacts early vertebrate development. Embryos exposed to nicotine become functionally paralyzed by 42 hpf suggesting that the neuromuscular system is compromised in exposed embryos. We previously demonstrated that secondary spinal motoneurons in nicotine-exposed embryos were delayed in development and that their axons made pathfinding errors (Svoboda, K.R., Vijayaraghaven, S., Tanguay, R.L., 2002. Nicotinic receptors mediate changes in spinal motoneuron development and axonal pathfinding in embryonic zebrafish exposed to nicotine. J. Neurosci. 22, 10731-10741). In that study, we did not consider the potential role that altered skeletal muscle development caused by nicotine exposure could play in contributing to the errors in spinal motoneuron axon pathfinding. In this study, we show that an alteration in skeletal muscle development occurs in tandem with alterations in spinal motoneuron development upon exposure to nicotine. The alteration in the muscle involves the binding of nicotine to the muscle-specific AChRs. The nicotine-induced alteration in muscle development does not occur in the zebrafish mutant (sofa potato, [sop]), which lacks muscle-specific AChRs. Even though muscle development is unaffected by nicotine exposure in sop mutants, motoneuron axonal pathfinding errors still occur in these mutants, indicating a direct effect of nicotine exposure on nervous system development.

Topical photosan-mediated photodynamic therapy for DMBA-induced hamster buccal pouch early cancer lesions: an in vivo study

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Hsu, Yih-Chih; Chang, Walter Hong-Shong; Chang, Junn-Liang; Liu, Kuang-Ting; Chiang, Chun-Pin; Liu, Chung-Ji; Chen, Chih-Ping

2011-03-01

Oral cancer has becomes the most prominent cancer disease in recent years in Taiwan. The reason is the betel nut chewing habit combing with smoking and alcohol-drinking lifestyle of people results in oral cancer becomes the fastest growth incident cancer amongst other major cancer diseases. In previous studies showed that photosan, haematoporphyrin derivative (HPD), has demonstrated effective PDT results on human head and neck disease studies. To avoid the systemic phototoxic effect of photosan, this study was designed to use a topical photosan-mediated PDT for treatment of DMBA-induced hamster buccal pouch cancerous lesions. DMBA was applied to one of the buccal pouches of hamsters thrice a week for 10 to 12 weeks. Cancerous lesions were induced and proven by histological examination. These DMBA-induced cancerous lesions were used for testing the efficacy of topical photosan-mediated PDT. Before PDT, fluorescence spectroscopy was used to determine when photosan reached its peak level in the lesional epithelial cells after topical application of photosan gel. We found that photosan reached its peak level in cancerous lesions about 13.5 min after topical application of photosan gel. The cancerous lesions in hamsters were then treated with topical photosan-mediated PDT (fluence rate: 600 mW/cm2; light exposure dose 200 J/cm2) using the portable Lumacare 635 nm fiber-guided light device. Visual examination demonstrated that topical photosan-mediated PDT was an applicable treatment modality for DMBA-induced hamster buccal pouch cancerous lesions.

A model for mild traumatic brain injury that induces limited transient memory impairment and increased levels of axon related serum biomarkers

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Elham eRostami

2012-07-01

Full Text Available Mild traumatic brain injury (mTBI is one of the most common neuronal insults and can lead to long-term disabilities. mTBI occurs when the head is exposed to a rapid acceleration-deceleration movement triggering axonal injuries. Our limited understanding of the underlying pathological changes makes it difficult to predict the outcome of mTBI. In this study we used a scalable rat model for rotational acceleration TBI, previously characterized for the threshold of axonal pathology. We have analyzed whether a TBI just above the defined threshold would induce any detectable behavioral changes and/or changes in serum biomarkers. The effect of injury on sensory motor functions, memory and anxiety were assessed by beam walking, radial arms maze and elevated plus maze at 3 to 7 days following TBI. The only behavioral deficits found were transient impairments in working and reference memory. Blood serum was analyzed at 1, 3 and 14 days after injury for changes in selected protein biomarkers. Serum levels of neurofilament heavy chain (NF-H and Tau, as well as S100B and myelin basic protein (MBP showed significant increases in the injured animals at all time points. No signs of macroscopic injuries such as intracerebral hematomas or contusions were found. Amyloid precursor protein (APP immunostaining indicated axonal injuries at all time points analyzed. In summary, this model mimics some of the key symptoms of mTBI, such as transient memory impairment, which is paralleled by an increase in serum biomarkers. Our findings suggest that serum biomarkers may be used to detect mTBI. The model provides a suitable foundation for further investigation of the underlying pathology of mTBI.

Brief electrical stimulation accelerates axon regeneration in the peripheral nervous system and promotes sensory axon regeneration in the central nervous system.

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Gordon, Tessa; Udina, Esther; Verge, Valerie M K; de Chaves, Elena I Posse

2009-10-01

Injured peripheral but not central nerves regenerate their axons but functional recovery is often poor. We demonstrate that prolonged periods of axon separation from targets and Schwann cell denervation eliminate regenerative capacity in the peripheral nervous system (PNS). A substantial delay of 4 weeks for all regenerating axons to cross a site of repair of sectioned nerve contributes to the long period of separation. Findings that 1h 20Hz bipolar electrical stimulation accelerates axon outgrowth across the repair site and the downstream reinnervation of denervated muscles in rats and human patients, provides a new and exciting method to improve functional recovery after nerve injuries. Drugs that elevate neuronal cAMP and activate PKA promote axon outgrowth in vivo and in vitro, mimicking the electrical stimulation effect. Rapid expression of neurotrophic factors and their receptors and then of growth associated proteins thereafter via cAMP, is the likely mechanism by which electrical stimulation accelerates axon outgrowth from the site of injury in both peripheral and central nervous systems.

Lesions of the lateral habenula increase voluntary ethanol consumption and operant self-administration, block yohimbine-induced reinstatement of ethanol seeking, and attenuate ethanol-induced conditioned taste aversion.

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Andrew K Haack

Full Text Available The lateral habenula (LHb plays an important role in learning driven by negative outcomes. Many drugs of abuse, including ethanol, have dose-dependent aversive effects that act to limit intake of the drug. However, the role of the LHb in regulating ethanol intake is unknown. In the present study, we compared voluntary ethanol consumption and self-administration, yohimbine-induced reinstatement of ethanol seeking, and ethanol-induced conditioned taste aversion in rats with sham or LHb lesions. In rats given home cage access to 20% ethanol in an intermittent access two bottle choice paradigm, lesioned animals escalated their voluntary ethanol consumption more rapidly than sham-lesioned control animals and maintained higher stable rates of voluntary ethanol intake. Similarly, lesioned animals exhibited higher rates of responding for ethanol in operant self-administration sessions. In addition, LHb lesion blocked yohimbine-induced reinstatement of ethanol seeking after extinction. Finally, LHb lesion significantly attenuated an ethanol-induced conditioned taste aversion. Our results demonstrate an important role for the LHb in multiple facets of ethanol-directed behavior, and further suggest that the LHb may contribute to ethanol-directed behaviors by mediating learning driven by the aversive effects of the drug.

4S RNA is transported axonally in normal and regenerating axons of the sciatic nerves of rats

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Lindquist, T D; Ingoglia, N A; Gould, R M [Departments of Physiology and Neuroscience, New Jersey Medical School, Newark, NJ, USA

1982-12-28

Experiments were designed to determine if following injection of (/sup 3/H)uridine into the lumbar spinal cord of the rat, (/sup 3/H)RNA could be demonstrated within axons of the sciatic nerve, and if 4S RNA is the predominant predominant RNA species present in these axons.

SAD kinases sculpt axonal arbors of sensory neurons through long and short-term responses to neurotrophin signals

Science.gov (United States)

Lilley, Brendan N.; Pan, Y. Albert; Sanes, Joshua R.

2013-01-01

SUMMARY Extrinsic cues activate intrinsic signaling mechanisms to pattern neuronal shape and connectivity. We showed previously that three cytoplasmic Ser/Thr kinases, LKB1, SAD-A and SAD-B, control early axon-dendrite polarization in forebrain neurons. Here we assess their role in other neuronal types. We found that all three kinases are dispensable for axon formation outside of the cortex, but that SAD kinases are required for formation of central axonal arbors by subsets of sensory neurons. The requirement for SAD kinases is most prominent in NT-3 dependent neurons. SAD kinases transduce NT-3 signals in two ways through distinct pathways. First, sustained NT-3/TrkC signaling increases SAD protein levels. Second, short duration NT-3/TrkC signals transiently activate SADs by inducing dephosphorylation of C-terminal domains, thereby allowing activating phosphorylation of the kinase domain. We propose that SAD kinases integrate long- and short duration signals from extrinsic cues to sculpt axon arbors within the CNS. PMID:23790753

A novel Drosophila injury model reveals severed axons are cleared through a Draper/MMP-1 signaling cascade

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Purice, Maria D; Ray, Arpita; Münzel, Eva Jolanda; Pope, Bernard J; Park, Daniel J; Speese, Sean D; Logan, Mary A

2017-01-01

Neural injury triggers swift responses from glia, including glial migration and phagocytic clearance of damaged neurons. The transcriptional programs governing these complex innate glial immune responses are still unclear. Here, we describe a novel injury assay in adult Drosophila that elicits widespread glial responses in the ventral nerve cord (VNC). We profiled injury-induced changes in VNC gene expression by RNA sequencing (RNA-seq) and found that responsive genes fall into diverse signaling classes. One factor, matrix metalloproteinase-1 (MMP-1), is induced in Drosophila ensheathing glia responding to severed axons. Interestingly, glial induction of MMP-1 requires the highly conserved engulfment receptor Draper, as well as AP-1 and STAT92E. In MMP-1 depleted flies, glia do not properly infiltrate neuropil regions after axotomy and, as a consequence, fail to clear degenerating axonal debris. This work identifies Draper-dependent activation of MMP-1 as a novel cascade required for proper glial clearance of severed axons. DOI: http://dx.doi.org/10.7554/eLife.23611.001 PMID:28825401

Outer Electrospun Polycaprolactone Shell Induces Massive Foreign Body Reaction and Impairs Axonal Regeneration through 3D Multichannel Chitosan Nerve Guides

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Sven Duda

2014-01-01

Full Text Available We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT. The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.

Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides.

Science.gov (United States)

Duda, Sven; Dreyer, Lutz; Behrens, Peter; Wienecke, Soenke; Chakradeo, Tanmay; Glasmacher, Birgit; Haastert-Talini, Kirsten

2014-01-01

We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.

Functional remineralization of dentin lesions using polymer-induced liquid-precursor process.

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Anora K Burwell

Full Text Available It was hypothesized that applying the polymer-induced liquid-precursor (PILP system to artificial lesions would result in time-dependent functional remineralization of carious dentin lesions that restores the mechanical properties of demineralized dentin matrix. 140 µm deep artificial caries lesions were remineralized via the PILP process for 7-28 days at 37°C to determine temporal remineralization characteristics. Poly-L-aspartic acid (27 KDa was used as the polymeric process-directing agent and was added to the remineralization solution at a calcium-to-phosphate ratio of 2.14 (mol/mol. Nanomechanical properties of hydrated artificial lesions had a low reduced elastic modulus (E(R = 0.2 GPa region extending about 70 μm into the lesion, with a sloped region to about 140 μm where values reached normal dentin (18-20 GPa. After 7 days specimens recovered mechanical properties in the sloped region by 51% compared to the artificial lesion. Between 7-14 days, recovery of the outer portion of the lesion continued to a level of about 10 GPa with 74% improvement. 28 days of PILP mineralization resulted in 91% improvement of E(R compared to the artificial lesion. These differences were statistically significant as determined from change-point diagrams. Mineral profiles determined by micro x-ray computed tomography were shallower than those determined by nanoindentation, and showed similar changes over time, but full mineral recovery occurred after 14 days in both the outer and sloped portions of the lesion. Scanning electron microscopy and energy dispersive x-ray analysis showed similar morphologies that were distinct from normal dentin with a clear line of demarcation between the outer and sloped portions of the lesion. Transmission electron microscopy and selected area electron diffraction showed that the starting lesions contained some residual mineral in the outer portions, which exhibited poor crystallinity. During remineralization

Guidance of retinal axons in mammals.

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Herrera, Eloísa; Erskine, Lynda; Morenilla-Palao, Cruz

2017-11-26

In order to navigate through the surrounding environment many mammals, including humans, primarily rely on vision. The eye, composed of the choroid, sclera, retinal pigmented epithelium, cornea, lens, iris and retina, is the structure that receives the light and converts it into electrical impulses. The retina contains six major types of neurons involving in receiving and modifying visual information and passing it onto higher visual processing centres in the brain. Visual information is relayed to the brain via the axons of retinal ganglion cells (RGCs), a projection known as the optic pathway. The proper formation of this pathway during development is essential for normal vision in the adult individual. Along this pathway there are several points where visual axons face 'choices' in their direction of growth. Understanding how these choices are made has advanced significantly our knowledge of axon guidance mechanisms. Thus, the development of the visual pathway has served as an extremely useful model to reveal general principles of axon pathfinding throughout the nervous system. However, due to its particularities, some cellular and molecular mechanisms are specific for the visual circuit. Here we review both general and specific mechanisms involved in the guidance of mammalian RGC axons when they are traveling from the retina to the brain to establish precise and stereotyped connections that will sustain vision. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of multinucleated giant cells and microglial degeneration in rats expressing a mutant Cu/Zn superoxide dismutase gene

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Streit Wolfgang J

2007-02-01

Full Text Available Abstract Background Microglial neuroinflammation is thought to play a role in the pathogenesis of amyotrophic lateral sclerosis (ALS. The purpose of this study was to provide a histopathological evaluation of the microglial neuroinflammatory response in a rodent model of ALS, the SOD1G93A transgenic rat. Methods Multiple levels of the CNS from spinal cord to cerebral cortex were studied in SOD1G93A transgenic rats during three stages of natural disease progression, including presymptomatic, early symptomatic (onset, and late symptomatic (end stage, using immuno- and lectin histochemical markers for microglia, such as OX-42, OX-6, and Griffonia simplicifolia isolectin B4. Results Our studies revealed abnormal aggregates of microglia forming in the spinal cord as early as the presymptomatic stage. During the symptomatic stages there was prominent formation of multinucleated giant cells through fusion of microglial cells in the spinal cord, brainstem, and red nucleus of the midbrain. Other brain regions, including substantia nigra, cranial nerve nuclei, hippocampus and cortex showed normal appearing microglia. In animals during end stage disease at 4–5 months of age virtually all microglia in the spinal cord gray matter showed extensive fragmentation of their cytoplasm (cytorrhexis, indicative of widespread microglial degeneration. Few microglia exhibiting nuclear fragmentation (karyorrhexis indicative of apoptosis were identified at any stage. Conclusion The current findings demonstrate the occurrence of severe abnormalities in microglia, such as cell fusions and cytorrhexis, which may be the result of expression of mutant SOD1 in these cells. The microglial changes observed are different from those that accompany normal microglial activation, and they demonstrate that aberrant activation and degeneration of microglia is part of the pathogenesis of motor neuron disease.

Appearance of radiation-induced lesions after radiotherapy for Hodgkin's disease of the mediastinum and lungs

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Zomer-Drozda, J [Instytut Onkologii, Warsaw (Poland)

1976-01-01

The incidence of radiation-induced lesions of lung tissue adjacent to the mediastinum and covered by radiation was established on the basis of a retrospective analysis of radiograms of 245 patients treated at the Institute of Oncology in Warsaw in the years 1951-1968, who received radiotherapy to the mediastinal lymph nodes. The radiation-induced lesions were divided into 4 grades depending on their extent and intensity of pulmonary tissue damage. Criteria for classification of radiation-induced fibrosis into the above mentioned grades were established. The correlation between radiation-induced injury and the doses of X-rays applied to the mediastinal lymph nodes was analysed. The importance of radiation-induced changes in the mediastinum and lungs for the diagnosis of recurrences in the irradiated fields, in the marginal areas and granulomatous infiltrations in pulmonary tissue is discussed.

A Mechanism of Virus-Induced Demyelination

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Jayasri Das Sarma

2010-01-01

Full Text Available Myelin forms an insulating sheath surrounding axons in the central and peripheral nervous systems and is essential for rapid propagation of neuronal action potentials. Demyelination is an acquired disorder in which normally formed myelin degenerates, exposing axons to the extracellular environment. The result is dysfunction of normal neuron-to-neuron communication and in many cases, varying degrees of axonal degeneration. Numerous central nervous system demyelinating disorders exist, including multiple sclerosis. Although demyelination is the major manifestation of most of the demyelinating diseases, recent studies have clearly documented concomitant axonal loss to varying degrees resulting in long-term disability. Axonal injury may occur secondary to myelin damage (outside-in model or myelin damage may occur secondary to axonal injury (inside-out model. Viral induced demyelination models, has provided unique imminent into the cellular mechanisms of myelin destruction. They illustrate mechanisms of viral persistence, including latent infections, virus reactivation and viral-induced tissue damage. These studies have also provided excellent paradigms to study the interactions between the immune system and the central nervous system (CNS. In this review we will discuss potential cellular and molecular mechanism of central nervous system axonal loss and demyelination in a viral induced mouse model of multiple sclerosis.

A novel pleiotropic effect of aspirin: Beneficial regulation of pro- and anti-inflammatory mechanisms in microglial cells.

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Kata, Diana; Földesi, Imre; Feher, Liliana Z; Hackler, Laszlo; Puskas, Laszlo G; Gulya, Karoly

2017-06-01

Aspirin, one of the most widely used non-steroidal anti-inflammatory drugs, has extensively studied effects on the cardiovascular system. To reveal further pleiotropic, beneficial effects of aspirin on a number of pro- and anti-inflammatory microglial mechanisms, we performed morphometric and functional studies relating to phagocytosis, pro- and anti-inflammatory cytokine production (IL-1β, tumor necrosis factor-α (TNF-α) and IL-10, respectively) and analyzed the expression of a number of inflammation-related genes, including those related to the above functions, in pure microglial cells. We examined the effects of aspirin (0.1mM and 1mM) in unchallenged (control) and bacterial lipopolysaccharide (LPS)-challenged secondary microglial cultures. Aspirin affected microglial morphology and functions in a dose-dependent manner as it inhibited LPS-elicited microglial activation by promoting ramification and the inhibition of phagocytosis in both concentrations. Remarkably, aspirin strongly reduced the pro-inflammatory IL-1β and TNF-α production, while it increased the anti-inflammatory IL-10 level in LPS-challenged cells. Moreover, aspirin differentially regulated the expression of a number of inflammation-related genes as it downregulated such pro-inflammatory genes as Nos2, Kng1, IL1β, Ptgs2 or Ccr1, while it upregulated some anti-inflammatory genes such as IL10, Csf2, Cxcl1, Ccl5 or Tgfb1. Thus, the use of aspirin could be beneficial for the prophylaxis of certain neurodegenerative disorders as it effectively ameliorates inflammation in the brain. Copyright © 2017 Elsevier Inc. All rights reserved.

Annexin-1 Mediates Microglial Activation and Migration via the CK2 Pathway during Oxygen–Glucose Deprivation/Reperfusion

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Shuangxi Liu

2016-10-01

Full Text Available Annexin-1 (ANXA1 has shown neuroprotective effects and microglia play significant roles during central nervous system injury, yet the underlying mechanisms remain unclear. This study sought to determine whether ANXA1 regulates microglial response to oxygen–glucose deprivation/reperfusion (OGD/R treatment and to clarify the downstream molecular mechanism. In rat hippocampal slices, OGD/R treatment enhanced the ANXA1 expression in neuron, the formyl peptide receptor (FPRs expression in microglia, and the microglial activation in the CA1 region (cornu ammonis 1. These effects were reversed by the FPRs antagonist Boc1. The cell membrane currents amplitude of BV-2 microglia (the microglial like cell-line was increased when treated with Ac2-26, the N-terminal peptide of ANXA1. Ac2-26 treatment enhanced BV-2 microglial migration whereas Boc1 treatment inhibited the migration. In BV-2 microglia, both the expression of the CK2 target phosphorylated α-E-catenin and the binding of casein kinase II (CK2 with α-E-catenin were elevated by Ac2-26, these effects were counteracted by the CK2 inhibitor TBB and small interfering (si RNA directed against transcripts of CK2 and FPRs. Moreover, both TBB and siRNA-mediated inhibition of CK2 blocked Ac2-26-mediated BV-2 microglia migration. Our findings indicate that ANXA1 promotes microglial activation and migration during OGD/R via FPRs, and CK2 target α-E-catenin phosphorylation is involved in this process.

Axonal Conduction Delays, Brain State, and Corticogeniculate Communication.

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Stoelzel, Carl R; Bereshpolova, Yulia; Alonso, Jose-Manuel; Swadlow, Harvey A

2017-06-28

Thalamocortical conduction times are short, but layer 6 corticothalamic axons display an enormous range of conduction times, some exceeding 40-50 ms. Here, we investigate (1) how axonal conduction times of corticogeniculate (CG) neurons are related to the visual information conveyed to the thalamus, and (2) how alert versus nonalert awake brain states affect visual processing across the spectrum of CG conduction times. In awake female Dutch-Belted rabbits, we found 58% of CG neurons to be visually responsive, and 42% to be unresponsive. All responsive CG neurons had simple, orientation-selective receptive fields, and generated sustained responses to stationary stimuli. CG axonal conduction times were strongly related to modulated firing rates (F1 values) generated by drifting grating stimuli, and their associated interspike interval distributions, suggesting a continuum of visual responsiveness spanning the spectrum of axonal conduction times. CG conduction times were also significantly related to visual response latency, contrast sensitivity (C-50 values), directional selectivity, and optimal stimulus velocity. Increasing alertness did not cause visually unresponsive CG neurons to become responsive and did not change the response linearity (F1/F0 ratios) of visually responsive CG neurons. However, for visually responsive CG neurons, increased alertness nearly doubled the modulated response amplitude to optimal visual stimulation (F1 values), significantly shortened response latency, and dramatically increased response reliability. These effects of alertness were uniform across the broad spectrum of CG axonal conduction times. SIGNIFICANCE STATEMENT Corticothalamic neurons of layer 6 send a dense feedback projection to thalamic nuclei that provide input to sensory neocortex. While sensory information reaches the cortex after brief thalamocortical axonal delays, corticothalamic axons can exhibit conduction delays of <2 ms to 40-50 ms. Here, in the corticogeniculate

Fcγ receptor-mediated inflammation inhibits axon regeneration.

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Gang Zhang

Full Text Available Anti-glycan/ganglioside antibodies are the most common immune effectors found in patients with Guillain-Barré Syndrome, which is a peripheral autoimmune neuropathy. We previously reported that disease-relevant anti-glycan autoantibodies inhibited axon regeneration, which echo the clinical association of these antibodies and poor recovery in Guillain-Barré Syndrome. However, the specific molecular and cellular elements involved in this antibody-mediated inhibition of axon regeneration are not previously defined. This study examined the role of Fcγ receptors and macrophages in the antibody-mediated inhibition of axon regeneration. A well characterized antibody passive transfer sciatic nerve crush and transplant models were used to study the anti-ganglioside antibody-mediated inhibition of axon regeneration in wild type and various mutant and transgenic mice with altered expression of specific Fcγ receptors and macrophage/microglia populations. Outcome measures included behavior, electrophysiology, morphometry, immunocytochemistry, quantitative real-time PCR, and western blotting. We demonstrate that the presence of autoantibodies, directed against neuronal/axonal cell surface gangliosides, in the injured mammalian peripheral nerves switch the proregenerative inflammatory environment to growth inhibitory milieu by engaging specific activating Fcγ receptors on recruited monocyte-derived macrophages to cause severe inhibition of axon regeneration. Our data demonstrate that the antibody orchestrated Fcγ receptor-mediated switch in inflammation is one mechanism underlying inhibition of axon regeneration. These findings have clinical implications for nerve repair and recovery in antibody-mediated immune neuropathies. Our results add to the complexity of axon regeneration in injured peripheral and central nervous systems as adverse effects of B cells and autoantibodies on neural injury and repair are increasingly recognized.

Cholesterol Perturbation in Mice Results in p53 Degradation and Axonal Pathology through p38 MAPK and Mdm2 Activation.

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Qingyu Qin

Full Text Available Perturbation of lipid metabolism, especially of cholesterol homeostasis, can be catastrophic to mammalian brain, as it has the highest level of cholesterol in the body. This notion is best illustrated by the severe progressive neurodegeneration in Niemann-Pick Type C (NPC disease, one of the lysosomal storage diseases, caused by mutations in the NPC1 or NPC2 gene. In this study, we found that growth cone collapse induced by genetic or pharmacological disruption of cholesterol egress from late endosomes/lysosomes was directly related to a decrease in axonal and growth cone levels of the phosphorylated form of the tumor suppressor factor p53. Cholesterol perturbation-induced growth cone collapse and decrease in phosphorylated p53 were reduced by inhibition of p38 mitogen-activated protein kinase (MAPK and murine double minute (Mdm2 E3 ligase. Growth cone collapse induced by genetic (npc1-/- or pharmacological modification of cholesterol metabolism was Rho kinase (ROCK-dependent and associated with increased RhoA protein synthesis; both processes were significantly reduced by P38 MAPK or Mdm2 inhibition. Finally, in vivo ROCK inhibition significantly increased phosphorylated p53 levels and neurofilaments in axons, and axonal bundle size in npc1-/- mice. These results indicate that NPC-related and cholesterol perturbation-induced axonal pathology is associated with an abnormal signaling pathway consisting in p38 MAPK activation leading to Mdm2-mediated p53 degradation, followed by ROCK activation. These results also suggest new targets for pharmacological treatment of NPC disease and other diseases associated with disruption of cholesterol metabolism.

Induction of neuronal axon outgrowth by Shati/Nat8l by energy metabolism in mice cultured neurons.

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Sumi, Kazuyuki; Uno, Kyosuke; Matsumura, Shohei; Miyamoto, Yoshiaki; Furukawa-Hibi, Yoko; Muramatsu, Shin-Ichi; Nabeshima, Toshitaka; Nitta, Atsumi

2015-09-09

A novel N-acetyltransferase, Shati/Nat8l, was identified in the nucleus accumbens of mice repeatedly treated with methamphetamine (METH). Shati/Nat8l has been reported to inhibit the pharmacological action induced by METH. Shati/Nat8l produces N-acetylaspartate from aspartate and acetyl-CoA. Previously, we reported that overexpression of Shati/Nat8l in nucleus accumbens attenuates the response to METH by N-acetylaspartylglutamate (which is derived from N-acetylaspartate)-mGluR3 signaling in the mice brain. In the present study, to clarify the type of cells that produce Shati/Nat8l, we carried out in-situ hybridization for the detection of Shati/Nat8l mRNA along with immunohistochemical studies using serial sections of mice brain. Shati/Nat8l mRNA was detected in neuronal cells, but not in astrocytes or microglia cells. Next, we investigated the function of Shati/Nat8l in the neuronal cells in mice brain; then, we used an adeno-associated virus vector containing Shati/Nat8l for transfection and overexpression of Shati/Nat8l protein into the primary cultured neurons to investigate the contribution toward the neuronal activity of Shati/Nat8l. Overexpression of Shati/Nat8l in the mice primary cultured neurons induced axonal growth, but not dendrite elongation at day 1.5 (DIV). This finding indicated that Shati/Nat8l contributes toward neuronal development. LY341495, a selective group II mGluRs antagonist, did not abolish this axonal growth, and N-acetylaspartylglutamate itself did not abolish axon outgrowth in the same cultured system. The cultured neurons overexpressing Shati/Nat8l contained high ATP, suggesting that axon outgrowth is dependent on energy metabolism. This study shows that Shati/Nat8l in the neuron may induce axon outgrowth by ATP synthesis and not through mGluR3 signaling.

Protective Effect of Repeatedly Preadministered Brazilian Propolis Ethanol Extract against Stress-Induced Gastric Mucosal Lesions in Rats

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Tadashi Nakamura

2014-01-01

Full Text Available The present study was conducted to clarify the protective effect of Brazilian propolis ethanol extract (BPEE against stress-induced gastric mucosal lesions in rats. The protective effect of BPEE against gastric mucosal lesions in male Wistar rats exposed to water-immersion restraint stress (WIRS for 6 h was compared between its repeated preadministration (50 mg/kg/day, 7 days and its single preadministration (50 mg/kg. The repeated BPEE preadministration attenuated WIRS-induced gastric mucosal lesions and gastric mucosal oxidative stress more largely than the single BPEE preadministration. In addition, the repeated BPEE preadministration attenuated neutrophil infiltration in the gastric mucosa of rats exposed to WIRS. The protective effect of the repeated preadministration of BPEE against WIRS-induced gastric mucosal lesions was similar to that of a single preadministration of vitamin E (250 mg/kg in terms of the extent and manner of protection. From these findings, it is concluded that BPEE preadministered in a repeated manner protects against gastric mucosal lesions in rats exposed to WIRS more effectively than BPEE preadministered in a single manner possibly through its antioxidant and anti-inflammatory actions.

Splenial lesions of the corpus callosum: Disease Spectrum and MRI findings

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Park, Sung Eun; Choi, Dae Seob; Shin, Hwa Seon; Baek, Hye Jin; Choi, Ho Cheol; Kim, Ji Eun; Choi, Hye Young; Park, Min Jung [Dept. of Radiology, Gyeongsang National University School of Medicine, Jinju (Korea, Republic of)

2017-08-01

The corpus callosum (CC) is the largest white matter structure in the brain, consisting of more than 200–250 million axons that provide a large connection mainly between homologous cerebral cortical areas in mirror image sites. The posterior end of the CC is the thickest part, which is called the slenium. Various diseases including congenital to acquired lesions including congenital anomalies, traumatic lesions, ischemic diseases, tumors, metabolic, toxic, degenerative, and demyelinating diseases, can involve the splenium of the CC and their clinical symptoms and signs are also variable. Therefore, knowledge of the disease entities and the imaging findings of lesions involving the splenium is valuable in clinical practice. MR imaging is useful for the detection and differential diagnosis of splenial lesions of the CC. In this study, we classify the disease entities and describe imaging findings of lesions involving the splenium of the CC based on our experiences and a review of the literature.

Protective effects of cannabidiol on lesion-induced intervertebral disc degeneration.

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João W Silveira

Full Text Available Disc degeneration is a multifactorial process that involves hypoxia, inflammation, neoinnervation, accelerated catabolism, and reduction in water and glycosaminoglycan content. Cannabidiol is the main non-psychotropic component of the Cannabis sativa with protective and anti-inflammatory properties. However, possible therapeutic effects of cannabidiol on intervertebral disc degeneration have not been investigated yet. The present study investigated the effects of cannabidiol intradiscal injection in the coccygeal intervertebral disc degeneration induced by the needle puncture model using magnetic resonance imaging (MRI and histological analyses. Disc injury was induced in the tail of male Wistar rats via a single needle puncture. The discs selected for injury were punctured percutaneously using a 21-gauge needle. MRI and histological evaluation were employed to assess the results. The effects of intradiscal injection of cannabidiol (30, 60 or 120 nmol injected immediately after lesion were analyzed acutely (2 days by MRI. The experimental group that received cannabidiol 120 nmol was resubmitted to MRI examination and then to histological analyses 15 days after lesion/cannabidiol injection. The needle puncture produced a significant disc injury detected both by MRI and histological analyses. Cannabidiol significantly attenuated the effects of disc injury induced by the needle puncture. Considering that cannabidiol presents an extremely safe profile and is currently being used clinically, these results suggest that this compound could be useful in the treatment of intervertebral disc degeneration.

Spinal muscular atrophy pathogenic mutations impair the axonogenic properties of axonal-survival of motor neuron.

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Locatelli, Denise; d'Errico, Paolo; Capra, Silvia; Finardi, Adele; Colciaghi, Francesca; Setola, Veronica; Terao, Mineko; Garattini, Enrico; Battaglia, Giorgio

2012-05-01

The axonal survival of motor neuron (a-SMN) protein is a truncated isoform of SMN1, the spinal muscular atrophy (SMA) disease gene. a-SMN is selectively localized in axons and endowed with remarkable axonogenic properties. At present, the role of a-SMN in SMA is unknown. As a first step to verify a link between a-SMN and SMA, we investigated by means of over-expression experiments in neuroblastoma-spinal cord hybrid cell line (NSC34) whether SMA pathogenic mutations located in the N-terminal part of the protein affected a-SMN function. We demonstrated here that either SMN1 missense mutations or small intragenic re-arrangements located in the Tudor domain consistently altered the a-SMN capability of inducing axonal elongation in vitro. Mutated human a-SMN proteins determined in almost all NSC34 motor neurons the growth of short axons with prominent morphologic abnormalities. Our data indicate that the Tudor domain is critical in dictating a-SMN function possibly because it is an association domain for proteins involved in axon growth. They also indicate that Tudor domain mutations are functionally relevant not only for FL-SMN but also for a-SMN, raising the possibility that also a-SMN loss of function may contribute to the pathogenic steps leading to SMA. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Hindsight regulates photoreceptor axon targeting through transcriptional control of jitterbug/Filamin and multiple genes involved in axon guidance in Drosophila.

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Oliva, Carlos; Molina-Fernandez, Claudia; Maureira, Miguel; Candia, Noemi; López, Estefanía; Hassan, Bassem; Aerts, Stein; Cánovas, José; Olguín, Patricio; Sierralta, Jimena

2015-09-01

During axon targeting, a stereotyped pattern of connectivity is achieved by the integration of intrinsic genetic programs and the response to extrinsic long and short-range directional cues. How this coordination occurs is the subject of intense study. Transcription factors play a central role due to their ability to regulate the expression of multiple genes required to sense and respond to these cues during development. Here we show that the transcription factor HNT regulates layer-specific photoreceptor axon targeting in Drosophila through transcriptional control of jbug/Filamin and multiple genes involved in axon guidance and cytoskeleton organization.Using a microarray analysis we identified 235 genes whose expression levels were changed by HNT overexpression in the eye primordia. We analyzed nine candidate genes involved in cytoskeleton regulation and axon guidance, six of which displayed significantly altered gene expression levels in hnt mutant retinas. Functional analysis confirmed the role of OTK/PTK7 in photoreceptor axon targeting and uncovered Tiggrin, an integrin ligand, and Jbug/Filamin, a conserved actin- binding protein, as new factors that participate of photoreceptor axon targeting. Moreover, we provided in silico and molecular evidence that supports jbug/Filamin as a direct transcriptional target of HNT and that HNT acts partially through Jbug/Filamin in vivo to regulate axon guidance. Our work broadens the understanding of how HNT regulates the coordinated expression of a group of genes to achieve the correct connectivity pattern in the Drosophila visual system. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 75: 1018-1032, 2015. © 2015 Wiley Periodicals, Inc.

Oxidative Stress and Proinflammatory Cytokines Contribute to Demyelination and Axonal Damage in a Cerebellar Culture Model of Neuroinflammation

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di Penta, Alessandra; Moreno, Beatriz; Reix, Stephanie; Fernandez-Diez, Begoña; Villanueva, Maite; Errea, Oihana; Escala, Nagore; Vandenbroeck, Koen; Comella, Joan X.; Villoslada, Pablo

2013-01-01

Background Demyelination and axonal damage are critical processes in the pathogenesis of multiple sclerosis (MS). Oxidative stress and pro-inflammatory cytokines elicited by inflammation mediates tissue damage. Methods/Principal Findings To monitor the demyelination and axonal injury associated with microglia activation we employed a model using cerebellar organotypic cultures stimulated with lipopolysaccharide (LPS). Microglia activated by LPS released pro-inflammatory cytokines (IL-1β, IL-6 and TNFα), and increased the expression of inducible nitric oxide synthase (iNOS) and production of reactive oxygen species (ROS). This activation was associated with demyelination and axonal damage in cerebellar cultures. Axonal damage, as revealed by the presence of non-phosphorylated neurofilaments, mitochondrial accumulation in axonal spheroids, and axonal transection, was associated with stronger iNOS expression and concomitant increases in ROS. Moreover, we analyzed the contribution of pro-inflammatory cytokines and oxidative stress in demyelination and axonal degeneration using the iNOS inhibitor ethyl pyruvate, a free-scavenger and xanthine oxidase inhibitor allopurinol, as well as via blockage of pro-inflammatory cytokines using a Fc-TNFR1 construct. We found that blocking microglia activation with ethyl pyruvate or allopurinol significantly decreased axonal damage, and to a lesser extent, demyelination. Blocking TNFα significantly decreased demyelination but did not prevented axonal damage. Moreover, the most common therapy for MS, interferon-beta, was used as an example of an immunomodulator compound that can be tested in this model. In vitro, interferon-beta treatment decreased oxidative stress (iNOS and ROS levels) and the release of pro-inflammatory cytokines after LPS stimulation, reducing axonal damage. Conclusion The model of neuroinflammation using cerebellar culture stimulated with endotoxin mimicked myelin and axonal damage mediated by the combination of

Neurotrophin Signaling via Long-Distance Axonal Transport

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Chowdary, Praveen D.; Che, Dung L.; Cui, Bianxiao

2012-05-01

Neurotrophins are a family of target-derived growth factors that support survival, development, and maintenance of innervating neurons. Owing to the unique architecture of neurons, neurotrophins that act locally on the axonal terminals must convey their signals across the entire axon for subsequent regulation of gene transcription in the cell nucleus. This long-distance retrograde signaling, a motor-driven process that can take hours or days, has been a subject of intense interest. In the last decade, live-cell imaging with high sensitivity has significantly increased our capability to track the transport of neurotrophins, their receptors, and subsequent signals in real time. This review summarizes recent research progress in understanding neurotrophin-receptor interactions at the axonal terminal and their transport dynamics along the axon. We emphasize high-resolution studies at the single-molecule level and also discuss recent technical advances in the field.

Axonal inclusions in the crab Hemigrapsus nudus.