Mixed Glial Cell Research Articles

First description of pharmacoresistant epilepsy due to independent bilateral hypothalamic hamartomas

Hypothalamic hamartomas (HHs) are rare developmental malformations consisting of mixed neurons and glial cells, usually unilaterally attached to the tuber cinereum or mammillary bodies. We report on two patients, both suffering from pharmacoresistant epilepsy, behavioural and cognitive disturbances. Ictal and interictal electroencephalographic (EEG) abnormalities appeared bilaterally and multiregionally with right-sided preponderance. Magnetic-resonance imaging (MRI) revealed independent bilateral hypothalamic hamartomas, more prominently on the right side. Endoscopic surgery of the right HH was performed in each patient, resulting in a significant seizure reduction in both cases. To the best of our knowledge, there are no other reports of independent bilateral HHs in the literature.

Arrays of microLEDs and astrocytes: biological amplifiers to optogenetically modulate neuronal networks reducing light requirement.

In the modern view of synaptic transmission, astrocytes are no longer confined to the role of merely supportive cells. Although they do not generate action potentials, they nonetheless exhibit electrical activity and can influence surrounding neurons through gliotransmitter release. In this work, we explored whether optogenetic activation of glial cells could act as an amplification mechanism to optical neural stimulation via gliotransmission to the neural network. We studied the modulation of gliotransmission by selective photo-activation of channelrhodopsin-2 (ChR2) and by means of a matrix of individually addressable super-bright microLEDs (μLEDs) with an excitation peak at 470 nm. We combined Ca2+ imaging techniques and concurrent patch-clamp electrophysiology to obtain subsequent glia/neural activity. First, we tested the μLEDs efficacy in stimulating ChR2-transfected astrocyte. ChR2-induced astrocytic current did not desensitize overtime, and was linearly increased and prolonged by increasing μLED irradiance in terms of intensity and surface illumination. Subsequently, ChR2 astrocytic stimulation by broad-field LED illumination with the same spectral profile, increased both glial cells and neuronal calcium transient frequency and sEPSCs suggesting that few ChR2-transfected astrocytes were able to excite surrounding not-ChR2-transfected astrocytes and neurons. Finally, by using the μLEDs array to selectively light stimulate ChR2 positive astrocytes we were able to increase the synaptic activity of single neurons surrounding it. In conclusion, ChR2-transfected astrocytes and μLEDs system were shown to be an amplifier of synaptic activity in mixed corticalneuronal and glial cells culture.

TRIL is involved in cytokine production in the brain following Escherichia coli infection.

TLR4 interactor with leucine-rich repeats (TRIL) is a brain-enriched accessory protein that is important in TLR3 and TLR4 signaling. In this study, we generated Tril(-/-) mice and examined TLR responses in vitro and in vivo. We found a role for TRIL in both TLR4 and TLR3 signaling in mixed glial cells, consistent with the high level of expression of TRIL in these cells. We also found that TRIL is a modulator of the innate immune response to LPS challenge and Escherichia coli infection in vivo. Tril(-/-) mice produce lower levels of multiple proinflammatory cytokines and chemokines specifically within the brain after E. coli and LPS challenge. Collectively, these data uncover TRIL as a mediator of innate immune responses within the brain, where it enhances neuronal cytokine responses to infection.

Effect of iron deficiency on the expression of insulin-like growth factor-II and its receptor in neuronal and glial cells

IntroductionMany studies have demonstrated that iron deficiency modifies the normal function of the central nervous system (CNS) and alters cognitive abilities. When cellular damage occurs in the CNS, neuroprotective mechanisms, such as the production of neurotrophic factors, are essential in order for nervous tissue to function correctly. Insulin-like growth factor II (IGF-II) is a neurotrophic factor that was recently shown to be involved in the normal functioning of cognitive processes in animal models. However, the impact of iron deficiency on the expression and function of this molecule has not yet been clarified. MethodsMixed primary cell cultures from the CNS were collected to simulate iron deficiency using deferoxamine. The expression of IGF-I, IGF-II, IGF-IR, and IGF-IIR was determined with the Western blot test. ResultsWe observed increased expression of IGF-II, along with a corresponding decrease in the expression of IGF-IIR, in iron-deficient (DFe) mixed primary cell cultures. We did not observe alterations in the expression of these proteins in isolated microglia or neuronal cultures under the same conditions. We did not detect differences in the expression of IGF-I and IGF-IR in DFe cultures. ConclusionsIn vitro iron deficiency increases the expression of IGF-II in mixed glial cell cultures, which may have a beneficial effect on brain tissue homeostasis in a situation in which iron availability is decreased.

Cytoprotective and anti-inflammatory effects of PAL31 overexpression in glial cells.

BackgroundAcute spinal cord injury (SCI) leads to a series of reactive changes and causes severe neurological deficits. A pronounced inflammation contributes to secondary pathology after SCI. Astroglia respond to SCI by proliferating, migrating, and altering phenotype. The impact of reactive gliosis on the pathogenesis of SCI is not fully understood. Our previous study has identified an inflammatory modulating protein, proliferation related acidic leucine-rich protein (PAL31) which is upregulated in the microglia/macrophage of injured cords. Because PAL31 participates in cell cycle progression and reactive astroglia often appears in the injured cord, we aim to examine whether PAL31 is involved in glial modulation after injury.ResultsEnhanced PAL31 expression was shown not only in microglia/macrophages but also in spinal astroglia after SCI. Cell culture study reveal that overexpression of PAL31 in mixed glial cells or in C6 astroglia significantly reduced LPS/IFNγ stimulation. Further, enhanced PAL31 expression in C6 astroglia protected cells from H2O2 toxicity; however, this did not affect its proliferative activity. The inhibiting effect of PAL31 on LPS/IFNγ stimulation was observed in glia or C6 after co-culture with neuronal cells. The results demonstrated that the overexpressed PAL31 in glial cells protected neuronal damages through inhibiting NF-kB signaling and iNOS.ConclusionsOur data suggest that PAL31upregulation might be beneficial after spinal cord injury. Reactive gliosis might become a good target for future therapeutic interventions.

Early release of high-mobility group box 1 (HMGB1) from neurons in experimental subarachnoid hemorrhage in vivo and in vitro.

BackgroundTranslocation of high-mobility group box 1 (HMGB1) from nucleus could trigger inflammation. Extracellular HMGB1 up-regulates inflammatory response in sepsis as a late mediator. However, little was known about its role in subarachnoid hemorrhage-inducible inflammation, especially in the early stage. This study aims to identify whether HMGB1 translocation occurred early after SAH and also to clarify the potential role of HMGB1 in brain injury following SAH.MethodsSprague-Dawley (SD) rats were randomly divided into sham group and SAH groups at 2 h, 12 h and on day 1, day 2. SAH groups suffered experimental subarachnoid hemorrhage by injection of 0.3 ml autoblood into the pre-chiasmatic cistern. Rats injected by recombinant HMGB1(rHMGB1) solution were divided into four groups according to different time points. Cultured neurons were assigned into control group and four hemoglobin (Hb) incubated groups. Mixed glial cells were cultured and stimulated in medium from neurons incubated by Hb. HMGB1 expression is measured by western blot analysis, real-time polymerase chain reaction (PCR), immunohistochemistry and immunofluorescence. Downstream nuclear factor kappa B (NF-κB) subunit P65 and inflammatory factor Interleukin 1β (IL-1β) were measured by western blot and real-time PCR, respectively. Brain injury was evaluated by cleaved caspase-3 staining.ResultsOur results demonstrated HMGB1 translocation occurred as early as 2 h after experimental SAH with mRNA and protein level increased. Immunohistochemistry and immunofluorescence results indicated cytosolic HMGB1 was mainly located in neurons while translocated HMGB1 could also be found in some microglia. After subarachnoid injection of rHMGB1, NF-κB, downstream inflammatory response and cleaved caspase-3 were up-regulated in the cortex compared to the saline control group. In-vitro, after Hb incubation, HMGB1 was also rapidly released from neurons to medium. Incubation with medium from neurons up-regulated IL-1β in mixed glial cells. This effect could be inhibited by HMGB1 specific inhibitor glycyrrhizic acid (GA) treatment.ConclusionHMGB1 was released from neurons early after SAH onset and might trigger inflammation as an upstream inflammatory mediator. Extracellular HMGB1 contributed to the brain injury after SAH. These results might have important implications during the administration of specific HMGB1 antagonists early in order to prevent or reduce inflammatory response following SAH.

Hyaluronic acid-based 3D culture model for in vitro testing of electrode biocompatibility.

This work describes the development of a robust and repeatable in vitro 3D culture model of glial scarring, which may be used to evaluate the foreign body response to electrodes and other implants in the central nervous system. The model is based on methacrylated hyaluronic acid, a hydrogel that may be photopolymerized to form an insoluble network. Hydrogel scaffolds were formed at four different macromer concentrations (0.50, 0.75, 1.00, and 1.50% (w/v)). As expected, the elastic modulus of the scaffolds increased with increasing macromer weight fraction. Adult rat brain tested under identical conditions had an elastic modulus range that spanned the elastic modulus of both the 0.50 and 0.75% (w/v) hydrogel samples. Gels formed with higher macromer weight fraction had decreased equilibrium swelling ratio and visibly thicker pore walls relative to gels formed with lower macromer weight fractions. Mixed glial cells (microglia and astrocytes) were then encapsulated in the HA scaffolds. Viability of the mixed cultures was most stable at a cell density of 1 × 10(7) cells/mL. Cell viability at the highest macromer weight fraction tested (1.50% (w/v)) was significantly lower than other tested gels (0.50, 0.75 and 1.00% (w/v)). The inflammatory response of microglia and astrocytes to a microelectrode inserted into the scaffold was assessed over a period of 2 weeks and closely represented that reported in vivo. Microglia responded first to the electrode (increased cell density at the electrode, and activated morphology) followed by astrocytes (appeared to line the electrode in a manner similar to glial scarring). All together, these results demonstrate the potential of the 3D in vitro model system to assess glial scarring in a robust and repeatable manner.

Involvement of CGRP in peripheral nerve injury-induced behavioral hypersensitivity and chemokine production (CCR5P.260)

Abstract Previously, we have observed increased expression of Calcitonin Gene Related Peptide (CGRP), a pro-nociceptive neuropeptide, along with selected cytokines and chemokines, in the lumbar spinal cord following spinal nerve L5 transection (L5Tx, a murine model of neuropathic pain) in BALB/c mice. To further study the effects of CGRP in neuropathic pain, we intrathecally (i.t.) injected a CGRP antagonist (CGRP8-37) into BABL/c mice following L5Tx. Mice injected with CGRP8-37 displayed a reduced L5Tx-induced mechanical hypersensitivity, but not heat hypersensitivity. CGRP8-37 also caused significant reduction of the level of lumbar spinal cord CCL5 (RANTES) post-L5Tx when compared to vehicle injected-mice and non-injected mice. i.t. injection of a CCL5 neutralizing antibody significantly inhibited L5Tx-induced mechanical hypersensitivity. To test whether CGRP played its pro-nociceptive role through stimulating glial response, mixed glial cells were treated with various doses of CGRP. CGRP induced a slight increase of CCL5 24 hours post-treatment, which was correlated with the increased expression of MAP Kinase (MAPK) signaling pathway molecules: p38 and JNK. Thus, CGRP may promote MAPK-mediated glial activation and the subsequent production of CCL5, which potentiate behavioral hypersensitivity following L5Tx.

Anti-viral effects of CGRP in mixed glial cells infected with LP-BM5 virus (VIR5P.1022)

Abstract LP-BM5 retrovirus infection is an established murine model used to study HIV infection in humans due to that susceptible strains of mice (including C57BL/6(B6) mice) develop immunodeficiency syndrome (termed as MAIDS) following LP-BM5 infection. Previously, we observed that calcitonin gene related protein (CGRP), a neuropeptide produced primarily by sensory neurons, reduced LP-BM5 viral loads in infected mixed glial cells (primarily astrocytes and microglia). The mechanism through which CGRP decreases the viral loads is still not known. To elucidate the role of CGRP in glial LP-BM5 infection, we first determined that CGRP did not induce an increased cell death post-infection or directly decrease the viral infectivity. Then, we investigated whether CGRP could affect viral infectivity by enhancing the glycosylation of the cell receptor for viral attachment, murine cationic amino acid transporter 1 (mCAT-1). Our data indicate that blocking glycosylation by Tunicamycin did not affect CGRP’s anti-viral effects. Further, we tested the involvement of p38 MAPK pathway in CGRP-induced inhibitory effects. Preliminary experiment using a p38 inhibitor, SB203580, suggests a p38 mediated mechanism. Future studies will further elucidate the role of p38 and examine the role of other CGRP downstream pathways on LPBM5 infection.

Prenatal cocaine exposure initiates the release of TIMP‐1 and MMP‐9 in primary neuronal and glial cell cultures (651.21)

Drug addiction is a complex phenomenon that is mediated by biochemical events sequential to repeated exposure to a drug. The mechanisms underlying drug addiction include processes similar to those operating in forms of synaptic plasticity. Recently, pro‐addicitve cytokines, tissue inhibitors of matrix metalloproteinases (TIMPs) and matrix metalloproteinases (MMPs) have been shown to influence neuronal plasticity consequent to repeated cocaine injections in animal models. The present study was designed to investigate the role of TIMP‐1 and MMP‐9 in the addiction neurobiology of offspring exposed to cocaine during gestation. Time pregnant Sprague‐Dawley rats were treated with 40 mg/kg of cocaine HCl on gestational day (GD) 10‐21. On postnatal day (PND) 2, the brain tissue of the pups was harvested to yield mixed primary neuronal and glial cell cultures. Primary cell cultures were also exposed to a second sub‐lethal dose of cocaine in vitro and their response was measured. An increase in TIMP‐1 and MMP‐9 expression was observed in prenatally exposed primary neuronal and glial cell cultures. Through in vivo and in vitro studies, these findings suggest that exposure to cocaine in utero initiates the release of pro‐addictive cytokines increasing the incidence of addiction in the affected offspring.Grant Funding Source: NIH‐NIMHD G12MD007582

Imipramine and fluoxetine inhibit LPS-induced activation and affect morphology of microglial cells in the rat glial culture

BackgroundRecent evidence has suggested that antidepressants evoke neuroprotective and immunomodulatory effects in the brain, partly at least, by inhibiting glia activation. This study has been conducted on the lipopolysaccharide (LPS)-stimulated primary rat mixed glial cell culture in order to better recognize the influence of imipramine (a tricyclic antidepressant) and fluoxetine (a selective serotonin reuptake inhibitor) on the important balance between pro- and anti-inflammatory cytokines produced by the glial cells. Moreover, microscopic observations were made to describe the morphological alterations in the studied cell cultures exposed to the drugs. MethodsThe effect of both antidepressants on TNF-α, IL-1β and IL-10 levels was determined by ELISA. The mRNA levels of mentioned cytokines were evaluated by qRT-PCR assay. Moreover, drug influence on the LPS-stimulated level of NF-κB p65 subunit in nuclear fraction was determined by the colorimetric transcription factor assay. ResultsAfter LPS-stimulation both drugs decreased concentration of TNF-α and IL-1β in culture medium and expression of TNF-α and IL-1β mRNAs in cellular extracts. They also diminished the LPS-induced nuclear translocation of NF-κB p65 subunit. In contrast, imipramine and fluoxetine induced a few-fold weaker suppressing effect on the levels of IL-10. Parallelly to the inhibition of the LPS-induced inflammatory response, the antidepressants prevented the morphological alterations of cells elicited by LPS. Moreover, in unstimulated cultures imipramine but not fluoxetine caused transformation of microglia cells into cells with neuron-like morphology. ConclusionsImipramine and fluoxetine, by modulating glia activation, may exert anti-inflammatory effects in the CNS. It also seems that microglia cells are important target particularly for imipramine.

Accelerated repair of demyelinated CNS lesions in the absence of non‐muscle myosin IIB

The oligodendrocyte (OL), the myelinating cell of the central nervous system, undergoes dramatic changes in the organization of its cytoskeleton as it differentiates from a precursor (oligodendrocyte precursor cells) to a myelin-forming cell. These changes include an increase in its branching cell processes, a phenomenon necessary for OL to myelinate multiple axon segments. We have previously shown that levels and activity of non-muscle myosin II (NMII), a regulator of cytoskeletal contractility, decrease as a function of differentiation and that inhibition of NMII increases branching and myelination of OL in coculture with neurons. We have also found that mixed glial cell cultures derived from NMIIB knockout mice display an increase in mature myelin basic protein-expressing OL compared with wild-type cultures. We have now extended our studies to investigate the role of NMIIB ablation on myelin repair following focal demyelination by lysolecithin. To this end, we generated an oligodendrocyte-specific inducible knockout model using a Plp-driven promoter in combination with a temporally activated CRE-ER fusion protein. Our data indicate that conditional ablation of NMII in adult mouse brain, expedites lesion resolution and remyelination by Plp+ oligodendrocyte-lineage cells when compared with that observed in control brains. Taken together, these data validate the function of NMII as that of a negative regulator of OL myelination in vivo and provide a novel target for promoting myelin repair in conditions such as multiple sclerosis.

Efecto de la deficiencia de hierro sobre la expresión de factor de crecimiento de insulina tipo II y su receptor en células neuronales y gliales

IntroductionMany studies have demonstrated that iron deficiency modifies the normal function of the central nervous system and alters cognitive abilities. When cellular damage occurs in the central nervous system, neuroprotective mechanisms, such as the production of neurotrophic factors, are essential in order for nervous tissue to function correctly. Insulin-like growth factor II (IGF- II) is a neurotrophic factor that was recently shown to be involved in the normal functioning of cognitive processes in animal models. However, the impact of iron deficiency on the expression and function of this molecule has not yet been clarified. MethodsMixed primary cell cultures from the central nervous system were collected to simulate iron deficiency using deferoxamine. The expression of IGF-I, IGF-II, IGF-IR, and IGF-IIR was determined with the western blot test. ResultsWe observed increased expression of IGF-II, along with a corresponding decrease in the expression of IGF-IIR, in iron-deficient mixed primary cell cultures. We did not observe alterations in the expression of these proteins in isolated microglia or neuronal cultures under the same conditions. We did not detect differences in the expression of IGF-I and IGF-IR in iron-deficient cultures. ConclusionsIn vitro iron deficiency increases the expression of IGF-II in mixed glial cell cultures, which may have a beneficial effect on brain tissue homeostasis in a situation in which iron availability is decreased.

Glial Cell Response to 3,4-(±)-Methylenedioxymethamphetamine and Its Metabolites

3,4-(±)-Methylenedioxymethamphetamine (MDMA) and 3,4-(±)-methylenedioxyamphetamine (MDA), a primary metabolite of MDMA, are phenylethylamine derivatives that cause serotonergic neurotoxicity. Although several phenylethylamine derivatives activate microglia, little is known about the effects of MDMA on glial cells, and evidence of MDMA-induced microglial activation remains ambiguous. We initially determined microglial occupancy status of the parietal cortex in rats at various time points following a single neurotoxic dose of MDMA (20mg/kg, SC). A biphasic microglial response to MDMA was observed, with peak microglial occupancy occurring 12- and 72-h post-MDMA administration. Because direct injection of MDMA into the brain does not produce neurotoxicity, the glial response to MDMA metabolites was subsequently examined in vivo and in vitro. Rats were treated with MDA (20mg/kg, SC) followed by ex vivo biopsy culture to determine the activation of quiescent microglia. A reactive microglial response was observed 72 h after MDA administration that subsided by 7 days. In contrast, intracerebroventricular (ICV) administration of MDA failed to produce a microglial response. However, thioether metabolites of MDA derived from α-methyldopamine (α-MeDA) elicited a robust microglial response following icv injection. We subsequently determined the direct effects of various MDMA metabolites on primary cultures of E18 hippocampal mixed glial and neuronal cells. 5-(Glutathion-S-yl)-α-MeDA, 2,5-bis-(glutathion-S-yl)-α-MeDA, and 5-(N-acetylcystein-S-yl)-α-MeDA all stimulated the proliferation of glial fibrillary acidic protein-positive astrocytes at a dose of 10 µM. The findings indicate that glial cells are activated in response to MDMA/MDA and support a role for thioether metabolites of α-MeDA in the neurotoxicity.

Noradrenaline acting on astrocytic β2-adrenoceptors induces neurite outgrowth in primary cortical neurons

The neurotransmitter noradrenaline (NA) has anti-inflammatory properties and promotes expression of neurotrophic factors in the central nervous system (CNS) via activation of glial adrenoceptors. Here we examined the ability of conditioned media (CM) from NA-treated glial cells to impact upon neuronal complexity. Primary rat cortical neurons were treated either directly with NA (1–10 μM), or treated with CM from NA-stimulated primary mixed glial cells. Neuronal complexity was assessed using Sholl analysis. Exposure of neurons to CM from NA-stimulated glial cells increased all indices of neuronal complexity, whereas direct exposure of neurons to NA did not. CM from NA-stimulated astrocytes, but not microglia, also increased neuronal complexity indicating a key role for astrocytes. The β-adrenergic subtype was implicated in this response as the increase was blocked by the β-adrenoceptor antagonist propanolol, but not by the α-adrenoceptor antagonist phentolamine. CM from glial cells treated with the β2-adrenoceptor agonists salmeterol and clenbuterol, but not the β1-adrenoceptor agonist xamoterol, mimicked the ability of NA to increase neuronal complexity. NA induced expression of a range of growth factors (BDNF, NGF-β, GDNF, FGF-2 and IL-6) in glial cells. In addition to this, the phosphatidylinositol 3-kinase (PI3K), mitogen activated protein kinase (MAPK) and JAK-STAT signalling pathways are implicated in NA CM-induced neuritic growth as inhibition of these pathways attenuated NA CM-induced neuritic growth. In conclusion, this study indicates a novel role for NA acting at glial β2-adrenoceptors to induce neuritic growth through the expression of soluble factors that elicit a neurotrophic action and increase neuronal complexity.

Modulation of Rho‐Rock signaling pathway protects oligodendrocytes against cytokine toxicity via PPAR‐α‐dependent mechanism

We earlier documented that lovastatin (LOV)-mediated inhibition of small Rho GTPases activity protects vulnerable oligodendrocytes (OLs) in mixed glial cell cultures stimulated with Th1 cytokines and in a murine model of multiple sclerosis (MS). However, the precise mechanism of OL protection remains unclear. We here employed genetic and biochemical approaches to elucidate the underlying mechanism that protects LOV treated OLs from Th1 (tumor necrosis factor-α) and Th17 (interleukin-17) cytokines toxicity in in vitro. Cytokines enhanced the reactive oxygen species (ROS) generation and mitochondrial membrane depolarization with corresponding lowering of glutathione (reduced) level in OLs and that were reverted by LOV. In addition, the expression of ROS detoxifying enzymes (catalase and superoxide-dismutase 2) and the transactivation of peroxisome proliferators-activated receptor (PPAR)-α/-β/-γ including PPAR-γ coactivator-1α were enhanced by LOV in similarly treated OLs. Interestingly, LOV-mediated inhibition of small Rho GTPases, i.e., RhoA and cdc42, and Rho-associated kinase (ROCK) activity enhanced the levels of PPAR ligands in OLs via extracellular signal regulated kinase (1/2)/p38 mitogen-activated protein kinase/cytoplasmic phospholipase 2/cyclooxygenase-2 signaling cascade activation. Small hairpin RNA transfection-based studies established that LOV mainly enhances PPAR-α and less so of PPAR-β and PPAR-γ transactivation that enhances ROS detoxifying defense in OLs. In support of this, the observed LOV-mediated protection was lacking in PPAR-α-deficient OLs exposed to cytokines. Collectively, these data provide unprecedented evidence that LOV-mediated inhibition of the Rho-ROCK signaling pathway boosts ROS detoxifying defense in OLs via PPAR-α-dependent mechanism that has implication in neurodegenerative disorders including MS.

AMP-Activated Protein Kinase Signaling Protects Oligodendrocytes that Restore Central Nervous System Functions in an Experimental Autoimmune Encephalomyelitis Model

AMP-activated protein kinase (AMPK) signaling is reported to protect neurons under pathologic conditions; however, its effect on oligodendrocytes (OLs) remains to be elucidated. We investigated whether AMPK signaling protects OLs to restore central nervous system (CNS) functions in an experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. Increased inflammation and demyelination in the CNS and peripheral immune responses were consistent with the observed clinical impairments in EAE animals, which were attenuated by treatment with metformin compared with vehicle. In addition, expressions of neurotrophic factors and of signatory genes of OL lineages were increased in the CNS of metformin-treated EAE animals. Likewise, metformin attenuated inflammatory response and enhanced expressions of neurotrophic factors, thereby protecting OLs via AMPK activation in mixed glial cultures stimulated with lipopolysaccharide/interferon γ invitro, as evidenced by analysis of the expression of signatory genes of O1(+)/MBP(+) OLs and their cellular populations. Metformin also attenuated oxidative stress and malondialdehyde-containing protein levels, with corresponding induction of antioxidative defenses in OLs exposed to cytokines via AMPK activation. These effects of metformin were evident in the CNS of EAE animals. These data provide evidence that AMPK signaling is crucial to protect OLs and, thus, CNS functions in EAE animals. We conclude that AMPK activators, including metformin, have the potential to limit neurologic deficits in multiple sclerosis and related neurodegenerative disorders.

Prenatal Cocaine Exposure Inhibits Neurite Outgrowth Through RAGE Pathway and Activates Altered Expression of Pro‐addictive Cytokines in Primary Neuronal and Glial Cell Cultures

BackgroundThe prevalence of neonates exposed to cociane continues to be an endemic within the U.S. An overwhelming amount of evidence has shown that prenatal cocaine exposure is associated with numerous neurological and behavioral abnormalities, as well as structural damage and a deficiency in neurodevelopment with no established underlying mechanisms.PurposeThe present study was designed to investigate biochemical events coupled to cocaine‐induced cytotoxicity of neurons and glial cells seen in exposed offspring.Research Approach:Time pregnant Sprague‐Dawley rats were treated with 40 mg/kg of cocaine HCl on gestational day (GD) 10–21. On postnatal day (PND) 3 the brain tissue of the pups was harvested to yield mixed neuronal and glial cell cultures. A cytokine antibody array determined a decrease in RAGE expression and an increase in TIMP‐1 expression in prenatally exposed pups. Immunocytochemistry (ICC) showed decreased neurite outgrowth in prenatally exposed neurons. ICC also determined there was an increase in dopamine (DA) in prenatally exposed primary cell cultures indicating the presence of DA receptors on astrocytes and oligodendrocytes.. Western Blot analysis quantitatively determined a variation of amphoterin (HMGB1) which is necessary for RAGE activation and pro‐inflammatory cytokine matrix metalloproteinase 9 (MMP‐9) protein expressions between the control and cocaine treated pups.ConclusionThrough in vivo and in vitro studies exposure to cocaine during gestation leads to marked alterations in morphology and function of primary neuronal and glial cell cultures. These findings suggest that exposure to cocaine in utero can ultimately increase the incidence of addiction and development of neurodegenerative diseases and neuropathologies in the affected offspring.

Abstract TMP109: Poly-ICLC-induced Blood Brain Barrier protection is independent of Toll-like Receptor 3 Signaling

Introduction: Preconditioning with a TLR3 ligand, polyinosinic polycytidylic acid (poly-ICLC), a synthetic dsRNA, protects against middle cerebral artery occlusion (MCAO). Using an in vitro model of the blood brain barrier (BBB) we found that Poly-ICLC stabilizes the BBB during ischemia through a mechanism involving IFNβ production from glial cells. We assessed the hypothesis that Poly-ICLC stabilization of the BBB and subsequent reduction of ischemic injury requires the presence of TLR3 on both endothelial and glial cells. Methods: BBB was modeled using a transwell co-culture system with primary brain microvascular endothelial cells (BMECs) in the upper chamber and primary mixed glial cells in the lower chamber. Poly-ICLC was administered 24h prior to 5h of oxygen glucose deprivation (OGD), which models stroke in vitro. Transendothelial electric resistance (TEER) and endothelial permeability were evaluated 24h after OGD and IFNβ secretion was assessed by ELISA. For in vivo studies, WT and TLR3 -/- mice were treated with poly-ICLC or vehicle 72h prior to MCAO and infarct volume was determined after 24h of reperfusion. Results: Poly-ICLC administered exclusively to the upper chamber containing BMECs, results in secretion of IFNβ from glial cells in the lower chamber and significant protection against OGD. To determine whether BMEC or glial expression of TLR3 was required for protection we generated BBB models with TLR3 deficient (TLR3-/-) BMECs in co-culture with WT mixed glial cells as well as WT BMECs in co-culture with TLR3 -/- mixed glial cells. Poly-ICLC preconditioning induced protection in the presence or absence of TLR3 suggesting that TLR3 signaling is not required for protection. This finding was supported further by in vivo data showing that poly-ICLC preconditioning protects TLR3 -/- mice against ischemic injury. Conclusions: Our results showed that poly-ICLC interaction with endothelial cells induces IFNβ production in glial cells to confer protection. This process does not require TLR3 expression on endothelial or glial cells suggesting that other dsRNA receptors (MDA5 and RIGI) may be important in poly-ICLC-induced protection.

Cobalt Chloride-induced Hypoxia Ameliorates NLRP3-Mediated Caspase-1 Activation in Mixed Glial Cultures

Hypoxia has been shown to promote inflammation, including the release of proinflammatory cytokines, but it is poorly investigated how hypoxia directly affects inflammasome signaling pathways. To explore whether hypoxic stress modulates inflammasome activity, we examined the effect of cobalt chloride (CoCl2)-induced hypoxia on caspase-1 activation in primary mixed glial cultures of the neonatal mouse brain. Unexpectedly, hypoxia induced by oxygen-glucose deprivation or CoCl2 treatment failed to activate caspase-1 in microglial BV-2 cells and primary mixed glial cultures. Of particular interest, CoCl2-induced hypoxic condition considerably inhibited NLRP3-dependent caspase-1 activation in mixed glial cells, but not in bone marrow-derived macrophages. CoCl2-mediated inhibition of NLRP3 inflammasome activity was also observed in the isolated brain microglial cells, but CoCl2 did not affect poly dA:dT-triggered AIM2 inflammasome activity in mixed glial cells. Our results collectively demonstrate that CoCl2-induced hypoxia may negatively regulate NLRP3 inflammasome signaling in brain glial cells, but its physiological significance remains to be determined.