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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Reverse triiodothyronine (rT3) attenuates ischemia-reperfusion injury

Highlights: • rT3 mitigates IR injury in vivo. • rT3 mitigates IR injury in vitro. • rT3 reduced IR induced oxidative stress. Hypothyroidism has been associated with better recovery from cerebral ischemia-reperfusion (IR) injury in humans. However, any therapeutic advantage of inducing hypothyroidism for mitigating IR injury without invoking the adverse effect of whole body hypothyroidism remains a challenge. We hypothesize that a deiodinase II (D2) inhibitor reverse triiodothyronine (rT3) may render brain specific hypometabolic state to ensue reduced damage during an acute phase of cerebral ischemia without affecting circulating thyroid hormone levels. Preclinical efficacy of rT3 as a neuroprotective agent was determined in rat model of middle cerebral artery occlusion (MCAO) induced cerebral IR and in oxygen glucose deprivation/reoxygenation (OGD/R) model in vitro. rT3 administration in rats significantly reduced neuronal injury markers, infarct size and neurological deficit upon ischemic insult. Similarly, rT3 increased cellular survival in primary cerebral neurons under OGD/R stress. Based on our results from both in vivo as well as in vitro models of ischemia reperfusion injury we propose rT3 as a novel therapeutic agent in reducing neuronal damage and improving stroke outcome.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Engineered nanomedicine for neuroregeneration: light emitting diode-mediated superparamagnetic iron oxide-gold core-shell nanoparticles functionalized by nerve growth factor

This article reports nerve growth factor functionalized superparamagnetic iron oxide–gold core-shell nanoparticles (NGF-SPIO-Au NPs), an engineered nanomedicine for non-invasive neuron regeneration when irradiated by a low-intensity light-emitting diode (LED). NGF-SPIO-Au NPs of 20 μg/ml, were tested on PC-12 neuron-like cells, irradiated by LEDs (525 nm, 1.09, 1.44, and 1.90 mW/cm2). A remarkable Ca 2+ influx was detected in differentiated PC-12 cells treated with NPs, irradiated by LED of 1.90 and 1.44 mW/cm 2 with great cell viability (>84%) and proliferations. The strong heat generated through their plasmonic surface upon LED irradiation on NGF-SPIO-Au NPs was observed. For cells treated with LED (1.90 mW/cm 2 ) and NGF-SPIO-Au NPs, a dramatic enhancement of neuronal differentiation (83%) and neurite outgrowth (51%) was found, and the upregulation of both the neural differentiation specific marker (β3-tubulin) and the cell adhesive molecule (integrin β1) was observed by the reverse transcription-polymerase chain reaction and western blot analysis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Berberine, a natural antidiabetes drug, attenuates glucose neurotoxicity and promotes Nrf2-related neurite outgrowth

Reactive oxygen intermediates production and apoptotic damage induced by high glucose are major causes of neuronal damage in diabetic neuropathy. Berberine (BBR), a natural antidiabetes drug with PI3K-activating activity, holds promise for diabetes because of its dual antioxidant and anti-apoptotic activities. We have previously reported that BBR attenuated H{sub 2}O{sub 2} neurotoxicity via activating the PI3K/Akt/Nrf2-dependent pathway. In this study, we further explored the novel protective mechanism of BBR on high glucose-induced apoptotic death and neurite damage of SH-SY5Y cells. Results indicated BBR (0.1–10 nM) significantly attenuated reactive oxygen species (ROS) production, nucleus condensation, and apoptotic death in high glucose-treated cells. However, AG1024, an inhibitor of insulin growth factor-1 (IGF-1) receptor, significantly abolished BBR protection against high glucose-induced neuronal death. BBR also increased Bcl-2 expression and decreased cytochrome c release. High glucose down-regulated IGF-1 receptor and phosphorylation of Akt and GSK-3β, the effects of which were attenuated by BBR treatment. BBR also activated nuclear erythroid 2-related factor 2 (Nrf2), the key antioxidative transcription factor, which is accompanied with up-regulation of hemeoxygenase-1 (HO-1). Furthermore, BBR markedly enhanced nerve growth factor (NGF) expression and promoted neurite outgrowth in high glucose-treated cells. To further determine the role of the Nrf2 in BBR neuroprotection, RNA interference directed against Nrf2 was used. Results indicated Nrf2 siRNA abolished BBR-induced HO-1, NGF, neurite outgrowth and ROS decrease. In conclusion, BBR attenuated high glucose-induced neurotoxicity, and we are the first to reveal this novel mechanism of BBR as an Nrf2 activator against glucose neurotoxicity, providing another potential therapeutic use of BBR on the treatment of diabetic complications. - Highlights: • BBR attenuates high glucose-induced ROS production and neuronal cell death. • BBR activates IGF-1/Akt/GSK-3β signaling under normal and high glucose conditions. • BBR enhances HO-1 and NGF expression through stimulating Nrf2 translocation. • BBR promotes neurite outgrowth through Nrf2-dependent pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Anti-neuroinflammatory efficacy of the aldose reductase inhibitor FMHM via phospholipase C/protein kinase C-dependent NF-κB and MAPK pathways

Aldose reductase (AR) has a key role in several inflammatory diseases: diabetes, cancer and cardiovascular diseases. Therefore, AR inhibition seems to be a useful strategy for anti-inflammation therapy. In the central nervous system (CNS), microglial over-activation is considered to be a central event in neuroinflammation. However, the effects of AR inhibition in CNS inflammation and its underlying mechanism of action remain unknown. In the present study, we found that FMHM (a naturally derived AR inhibitor from the roots of Polygala tricornis Gagnep.) showed potent anti-neuroinflammatory effects in vivo and in vitro by inhibiting microglial activation and expression of inflammatory mediators. Mechanistic studies showed that FMHM suppressed the activity of AR-dependent phospholipase C/protein kinase C signaling, which further resulted in downstream inactivation of the IκB kinase/IκB/nuclear factor-kappa B (NF-κB) inflammatory pathway. Therefore, AR inhibition-dependent NF-κB inactivation negatively regulated the transcription and expression of various inflammatory genes. AR inhibition by FMHM exerted neuroprotective effects in lipopolysaccharide-induced neuron–microglia co-cultures. These findings suggested that AR is a potential target for neuroinflammation inhibition and that FMHM could be an effective agent for treating or preventing neuroinflammatory diseases. - Highlights: • FMHM is a natural-derived aldose reductase (AR) inhibitor. • FMHM inhibits various neuroinflammatory mediator productions in vitro and in vivo. • FMHM inhibits neuroinflammation via aldose reductase/PLC/PKC-dependent NF-κB pathway. • FMHM inhibits neuroinflammation via aldose reductase/PLC/PKC-dependent MAPK pathway. • FMHM protects neurons against inflammatory injury in microglia-neuron co-cultures.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Subneurotoxic copper(II)-induced NF-κB-dependent microglial activation is associated with mitochondrial ROS

Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-α (TNF-α) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxic concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-α and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-α and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced IkB-α expression as well as phosphorylation and translocation of nuclear factor-κB (NF-κB) p65 and was blocked by NF-κB inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-α and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-κB-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation. - Highlights: • Subneurotoxic copper(II) triggers NF-κB-dependent microglial activation. • This activation leads to hippocampal neuronal death. • This activation may involve mitochondria-derived reactive oxygen species.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Oral intake of hydrogen-rich water ameliorated chlorpyrifos-induced neurotoxicity in rats

Chronic exposure to low-levels of organophosphate (OP) compounds, such as chlorpyrifos (CPF), induces oxidative stress and could be related to neurological disorders. Hydrogen has been identified as a novel antioxidant which could selectively scavenge hydroxyl radicals. We explore whether intake of hydrogen-rich water (HRW) can protect Wistar rats from CPF-induced neurotoxicity. Rats were gavaged daily with 6.75 mg/kg body weight (1/20 LD{sub 50}) of CPF and given HRW by oral intake. Nissl staining and electron microscopy results indicated that HRW intake had protective effects on the CPF-induced damage of hippocampal neurons and neuronal mitochondria. Immunostaining results showed that the increased glial fibrillary acidic protein (GFAP) expression in astrocytes induced by CPF exposure can be ameliorated by HRW intake. Moreover, HRW intake also attenuated CPF-induced oxidative stress as evidenced by enhanced level of MDA, accompanied by an increase in GSH level and SOD and CAT activity. Acetylcholinesterase (AChE) activity tests showed significant decrease in brain AChE activity after CPF exposure, and this effect can be ameliorated by HRW intake. An in vitro study demonstrated that AChE activity was more intense in HRW than in normal water with or without chlorpyrifos-oxon (CPO), the metabolically-activated form of CPF. These observations suggest that HRW intake can protect rats from CPF-induced neurotoxicity, and the protective effects of hydrogen may be mediated by regulating the oxidant and antioxidant status of rats. Furthermore, this work defines a novel mechanism of biological activity of hydrogen by directly increasing the AChE activity. - Highlights: • Hydrogen molecules protect rats from CPF-induced damage of hippocampal neurons. • The increased GFAP expression induced by CPF can also be ameliorated by hydrogen. • Hydrogen molecules attenuated the increase in CPF-induced oxidative stress. • Hydrogen molecules attenuated AChE inhibition in vivo and in vitro. • Hydrogen molecules have direct effect on the modulation of AChE activity in vitro.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Arsenic inhibits hedgehog signaling during P19 cell differentiation

Arsenic is a toxicant found in ground water around the world, and human exposure mainly comes from drinking water or from crops grown in areas containing arsenic in soils or water. Epidemiological studies have shown that arsenic exposure during development decreased intellectual function, reduced birth weight, and altered locomotor activity, while in vitro studies have shown that arsenite decreased muscle and neuronal cell differentiation. The sonic hedgehog (Shh) signaling pathway plays an important role during the differentiation of both neurons and skeletal muscle. The purpose of this study was to investigate whether arsenic can disrupt Shh signaling in P19 mouse embryonic stem cells, leading to changes muscle and neuronal cell differentiation. P19 embryonic stem cells were exposed to 0, 0.25, or 0.5 μM of sodium arsenite for up to 9 days during cell differentiation. We found that arsenite exposure significantly reduced transcript levels of genes in the Shh pathway in both a time and dose-dependent manner. This included the Shh ligand, which was decreased 2- to 3-fold, the Gli2 transcription factor, which was decreased 2- to 3-fold, and its downstream target gene Ascl1, which was decreased 5-fold. GLI2 protein levels and transcriptional activity were also reduced. However, arsenic did not alter GLI2 primary cilium accumulation or nuclear translocation. Moreover, additional extracellular SHH rescued the inhibitory effects of arsenic on cellular differentiation due to an increase in GLI binding activity. Taken together, we conclude that arsenic exposure affected Shh signaling, ultimately decreasing the expression of the Gli2 transcription factor. These results suggest a mechanism by which arsenic disrupts cell differentiation. - Highlights: • Arsenic exposure decreases sonic hedgehog pathway-related gene expression. • Arsenic decreases GLI2 protein levels and transcriptional activity in P19 cells. • Arsenic exposure does not alter the levels of SHH expression and GLI2 primary cilum accumulation. • Induction of the Shh pathway rescues arsenic's inhibitory effects on cell differentiation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Improving in vitro to in vivo extrapolation by incorporating toxicokinetic measurements: A case study of lindane-induced neurotoxicity

Approaches for extrapolating in vitro toxicity testing results for prediction of human in vivo outcomes are needed. The purpose of this case study was to employ in vitro toxicokinetics and PBPK modeling to perform in vitro to in vivo extrapolation (IVIVE) of lindane neurotoxicity. Lindane cell and media concentrations in vitro, together with in vitro concentration-response data for lindane effects on neuronal network firing rates, were compared to in vivo data and model simulations as an exercise in extrapolation for chemical-induced neurotoxicity in rodents and humans. Time- and concentration-dependent lindane dosimetry was determined in primary cultures of rat cortical neurons in vitro using “faux” (without electrodes) microelectrode arrays (MEAs). In vivo data were derived from literature values, and physiologically based pharmacokinetic (PBPK) modeling was used to extrapolate from rat to human. The previously determined EC{sub 50} for increased firing rates in primary cultures of cortical neurons was 0.6 μg/ml. Media and cell lindane concentrations at the EC{sub 50} were 0.4 μg/ml and 7.1 μg/ml, respectively, and cellular lindane accumulation was time- and concentration-dependent. Rat blood and brain lindane levels during seizures were 1.7–1.9 μg/ml and 5–11 μg/ml, respectively. Brain lindane levels associated with seizures in rats and those predicted for humans (average = 7 μg/ml) by PBPK modeling were very similar to in vitro concentrations detected in cortical cells at the EC{sub 50} dose. PBPK model predictions matched literature data and timing. These findings indicate that in vitro MEA results are predictive of in vivo responses to lindane and demonstrate a successful modeling approach for IVIVE of rat and human neurotoxicity. - Highlights: • In vitro to in vivo extrapolation for lindane neurotoxicity was performed. • Dosimetry of lindane in a micro-electrode array (MEA) test system was assessed. • Cell concentrations at the MEA EC{sub 50} equaled rat brain levels associated with seizure. • PBPK-predicted human brain levels at seizure also equaled EC{sub 50} cell concentrations. • In vitro MEA results are predictive of lindane in vivo dose–response in rats/humans.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

17β-trenbolone, an anabolic–androgenic steroid as well as an environmental hormone, contributes to neurodegeneration

Both genetic and environmental factors contribute to neurodegenerative disorders. In a large number of neurodegenerative diseases (for example, Alzheimer's disease (AD)), patients do not carry the mutant genes. Other risk factors, for example the environmental factors, should be evaluated. 17β-trenbolone is a kind of environmental hormone as well as an anabolic–androgenic steroid. 17β-trenbolone is used as a growth promoter for livestock in the USA. Also, a large portion of recreational exercisers inject 17β-trenbolone in large doses and for very long time to increase muscle and strength. 17β-trenbolone is stable in the environment after being excreted. In the present study, 17β-trenbolone was administered to adult and pregnant rats and the primary hippocampal neurons. 17β-trenbolone's distribution and its effects on serum hormone levels and Aβ42 accumulation in vivo and its effects on AD related parameters in vitro were assessed. 17β-trenbolone accumulated in adult rat brain, especially in the hippocampus, and in the fetus brain. It altered Aβ42 accumulation. 17β-trenbolone induced apoptosis of primary hippocampal neurons in vitro and resisted neuroprotective function of testosterone. Presenilin-1 protein expression was down-regulated while β-amyloid peptide 42 (Aβ42) production and caspase-3 activities were increased. Both androgen and estrogen receptors mediated the processes. 17β-trenbolone played critical roles in neurodegeneration. Exercisers who inject large doses of trenbolone and common people who are exposed to 17β-trenbolone by various ways are all influenced chronically and continually. Identification of such environmental risk factors will help us take early prevention measure to slow down the onset of neurodegenerative disorders. - Highlights: • The widely used anabolic–androgenic steroid 17β-trenbolone has neurotoxicity. • 17β-trenbolone crosses the blood brain barrier and placental barrier. • Rat has high level of 17β-trenbolone in hippocampus after intramuscular injection. • 17β-trenbolone induces apoptosis of primary hippocampal neurons. • 17β-trenbolone affects Alzheimer's disease-related proteins Aβ42 and presenilin-1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Tunicamycin-induced unfolded protein response in the developing mouse brain

Accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) causes ER stress, resulting in the activation of the unfolded protein response (UPR). ER stress and UPR are associated with many neurodevelopmental and neurodegenerative disorders. The developing brain is particularly susceptible to environmental insults which may cause ER stress. We evaluated the UPR in the brain of postnatal mice. Tunicamycin, a commonly used ER stress inducer, was administered subcutaneously to mice of postnatal days (PDs) 4, 12 and 25. Tunicamycin caused UPR in the cerebral cortex, hippocampus and cerebellum of mice of PD4 and PD12, which was evident by the upregulation of ATF6, XBP1s, p-eIF2α, GRP78, GRP94 and MANF, but failed to induce UPR in the brain of PD25 mice. Tunicamycin-induced UPR in the liver was observed at all stages. In PD4 mice, tunicamycin-induced caspase-3 activation was observed in layer II of the parietal and optical cortex, CA1–CA3 and the subiculum of the hippocampus, the cerebellar external germinal layer and the superior/inferior colliculus. Tunicamycin-induced caspase-3 activation was also shown on PD12 but to a much lesser degree and mainly located in the dentate gyrus of the hippocampus, deep cerebellar nuclei and pons. Tunicamycin did not activate caspase-3 in the brain of PD25 mice and the liver of all stages. Similarly, immature cerebellar neurons were sensitive to tunicamycin-induced cell death in culture, but became resistant as they matured in vitro. These results suggest that the UPR is developmentally regulated and the immature brain is more susceptible to ER stress. - Highlights: • Tunicamycin caused a development-dependent UPR in the mouse brain. • Immature brain was more susceptible to tunicamycin-induced endoplasmic reticulum stress. • Tunicamycin caused more neuronal death in immature brain than mature brain. • Tunicamycin-induced neuronal death is region-specific.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Prenatal nicotinic exposure upregulates pulmonary C-fiber NK1R expression to prolong pulmonary C-fiber-mediated apneic response

Prenatal nicotinic exposure (PNE) prolongs bronchopulmonary C-fiber (PCF)-mediated apneic response to intra-atrial bolus injection of capsaicin in rat pups. The relevant mechanisms remain unclear. Pulmonary substance P and adenosine and their receptors (neurokinin-A receptor, NK1R and ADA{sub 1} receptor, ADA{sub 1}R) and transient receptor potential cation channel subfamily V member 1 (TRPV1) expressed on PCFs are critical for PCF sensitization and/or activation. Here, we compared substance P and adenosine in BALF and NK1R, ADA{sub 1}R, and TRPV1 expression in the nodose/jugular (N/J) ganglia (vagal pulmonary C-neurons retrogradely labeled) between Ctrl and PNE pups. We found that PNE failed to change BALF substance P and adenosine content, but significantly upregulated both mRNA and protein TRPV1 and NK1R in the N/J ganglia and only NK1R mRNA in pulmonary C-neurons. To define the role of NK1R in the PNE-induced PCF sensitization, the apneic response to capsaicin (i.v.) without or with pretreatment of SR140333 (a peripheral and selective NK1R antagonist) was compared and the prolonged apnea by PNE significantly shortened by SR140333. To clarify if the PNE-evoked responses depended on action of nicotinic acetylcholine receptors (nAChRs), particularly α7nAChR, mecamylamine or methyllycaconitine (a general nAChR or a selective α7nAChR antagonist) was administrated via another mini-pump over the PNE period. Mecamylamine or methyllycaconitine eliminated the PNE-evoked mRNA and protein responses. Our data suggest that PNE is able to elevate PCF NK1R expression via activation of nAChRs, especially α7nAChR, which likely contributes to sensitize PCFs and prolong the PCF-mediated apneic response to capsaicin. - Highlights: • PNE upregulated NK1R and TRPV1 gene and protein expression in the N/J ganglia. • PNE only elevated NK1R mRNA in vagal pulmonary C-neurons. • Blockage of peripheral NK1R reduced the PNE-induced PCF sensitization. • PNE induced gene and protein changes in NK1R and TRPV1 dependent on action of α7nAChR.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Investigation of the therapeutic potential of N-acetyl cysteine and the tools used to define nigrostriatal degeneration in vivo

The glutathione precursor N-acetyl-L-cysteine (NAC) is currently being tested on Parkinson's patients for its neuroprotective properties. Our studies have shown that NAC can elicit protection in glutathione-independent manners in vitro. Thus, the goal of the present study was to establish an animal model of NAC-mediated protection in which to dissect the underlying mechanism. Mice were infused intrastriatally with the oxidative neurotoxicant 6-hydroxydopamine (6-OHDA; 4 μg) and administered NAC intraperitoneally (100 mg/kg). NAC-treated animals exhibited higher levels of the dopaminergic terminal marker tyrosine hydroxylase (TH) in the striatum 10d after 6-OHDA. As TH expression is subject to stress-induced modulation, we infused the tracer FluoroGold into the striatum to retrogradely label nigrostriatal projection neurons. As expected, nigral FluoroGold staining and cell counts of FluoroGold{sup +} profiles were both more sensitive measures of nigrostriatal degeneration than measurements relying on TH alone. However, NAC failed to protect dopaminergic neurons 3 weeks following 6-OHDA, an effect verified by four measures: striatal TH levels, nigral TH levels, nigral TH{sup +} cell counts, and nigral FluoroGold levels. Some degree of mild toxicity of FluoroGold and NAC was evident, suggesting that caution must be exercised when relying on FluoroGold as a neuron-counting tool and when designing experiments with long-term delivery of NAC—such as clinical trials on patients with chronic disorders. Finally, the strengths and limitations of the tools used to define nigrostriatal degeneration are discussed. - Highlights: • N-acetyl cysteine (NAC) was injected into animals infused with the toxicant 6-OHDA. • Retrograde tracing with FluoroGold was used to define nigrostriatal cell loss. • Infrared Odyssey imaging and cell counts were used to screen for nigral cell loss. • NAC protected transiently against 6-OHDA but this effect waned over time. • Mildly toxic effects of chronic NAC delivery may influence future clinical trials.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Metformin, besides exhibiting strong in vivo anti-inflammatory properties, increases mptp-induced damage to the nigrostriatal dopaminergic system

Metformin is a widely used oral antidiabetic drug with known anti-inflammatory properties due to its action on AMPK protein. This drug has shown a protective effect on various tissues, including cortical neurons. The aim of this study was to determine the effect of metformin on the dopaminergic neurons of the substantia nigra of mice using the animal model of Parkinson's disease based on the injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, an inhibitor of the mitochondrial complex I. In vivo and in vitro experiments were used to study the activation of microglia and the damage of the dopaminergic neurons. Our results show that metformin reduced microglial activation measured both at cellular and molecular levels. Rather than protecting, metformin exacerbated dopaminergic damage in response to MPTP. Our data suggest that, contrary to other brain structures, metformin treatment could be deleterious for the dopaminergic system. Hence, metformin treatment may be considered as a risk factor for the development of Parkinson's disease. - Highlights: • Metformin treatment decreases microglial activation in the MPTP model of Parkinson's disease. • Metformin treatment increases the neurodegeneration in the MPTP model of Parkinson's disease, both in vivo and vitro. • Metformin treatment could be a risk factor for the development of Parkinson's disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Modulation of the heart's electrical properties by the anticonvulsant drug retigabine

Retigabine, currently used as antiepileptic drug, has a wide range of potential medical uses. Administration of the drug in patients can lead to QT interval prolongation in the electrocardiogram and to cardiac arrhythmias in rare cases. This suggests that the drug may perturb the electrical properties of the heart, and the underlying mechanisms were investigated here. Effects of retigabine on currents through human cardiac ion channels, heterologously expressed in tsA-201 cells, were studied in whole-cell patch-clamp experiments. In addition, the drug's impact on the cardiac action potential was tested. This was done using ventricular cardiomyocytes isolated from Langendorff-perfused guinea pig hearts and cardiomyocytes derived from human induced pluripotent stem cells. Further, to unravel potential indirect effects of retigabine on the heart which might involve the autonomic nervous system, membrane potential and noradrenaline release from sympathetic ganglionic neurons were measured in the absence and presence of the drug. Retigabine significantly inhibited currents through hKv11.1 potassium, hNav1.5 sodium, as well as hCav1.2 calcium channels, but only in supra-therapeutic concentrations. In a similar concentration range, the drug shortened the action potential in both guinea pig and human cardiomyocytes. Therapeutic concentrations of retigabine, on the other hand, were sufficient to inhibit the activity of sympathetic ganglionic neurons. We conclude that retigabine- induced QT interval prolongation, and the reported cases of cardiac arrhythmias after application of the drug in a typical daily dose range, cannot be explained by a direct modulatory effect on cardiac ion channels. They are rather mediated by indirect actions at the level of the autonomic nervous system. - Highlights: • We study effects of anticonvulsant retigabine on the heart's electrical properties. • Retigabine does not modulate cardiac ion channels in therapeutic concentrations. • The activity of sympathetic ganglionic neurons is inhibited by retigabine. • Ganglionic block may generate QT interval prolongation and cardiac arrhythmias.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

High glucose-induced defective thrombospondin-1 release from astrocytes via TLR9 activation contributes to the synaptic protein loss

Highlights: • High glucose (30 mM) impaired TSP-1 secretion from astrocytes, resulting in neuronal synaptic proteins loss. • High glucose (30 mM) induced TLR9 activation and ROS generation in astrocytes. • Defective TSP-1 secretion from astrocytes was mediated by TLR9-ROS signaling. Diabetes, characterized by chronic hyperglycemia, is known to induce synaptic degeneration in the brain, thereby resulting in cognitive dysfunction. Thrombospondin-1(TSP-1), the secreted protein produced by astrocytes, plays a crucial role in promoting synapse formation. Toll-like receptor 9 (TLR9) has been widely known to initiate the innate immune response. We recently reported TLR9 activation in neurons results in tau hyperphosphorylation induced by HG in vitro. Its activation has been also considered to mediate oxidative stress and astrocytic dysfunction under pathological circumstance. However, whether astrocytic TSP-1 alteration plays a role in synaptic protein loss under high glucose condition and whether TLR9 activation is involved in this process have not been reported. In this study, we found that primary mouse astrocytes incubated in high glucose (30 mM) induced a significant decreased TSP-1 secretion and increased intracellular contents of TSP-1 without affecting transcription level. Addition of conditioned medium from high glucose (30 mM) treated astrocytes to the primary neurons exhibited reduced synaptic proteins expression, which was attenuated by treatment with exogenous rTSP-1. In addition, we demonstrated that TLR9 activation along with reactive oxygen species (ROS) generation in astrocytes was induced by high glucose (30 mM). Furthermore, we explored the relationship between TLR9 activation and TSP-1 production. Both TLR9 deficiency and the antioxidant N-acetyl-L-cysteine treatment improved altered intra- and extracellular TSP-1 levels under high glucose condition. Together, our findings suggest that high glucose (30 mM) impairs TSP-1 secretion from astrocytes, which depends on astrocytic dysfunction associated with TLR9 activation mediated ROS signaling, ultimately contributing to the synaptic proteins loss.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Cerebrospinal fluid from Alzheimer patients affects cell-mediated nerve growth factor production and cell survival in vitro

Highlights: • Alzheimer's disease is characterized by early degeneration of cholinergic neurons and decreased levels of nerve growth factor. • Encapsulated cell bio-delivery (ECB) is a potential treatment strategy. • Neither Aβ{sub 40} nor Aβ{sub 42} had any major impact on cell viability or NGF-production. • IL-1β dose-dependently affected NGF-production over time. • Proteins involved in inflammatory pathways may have negative effect on ECB cells. Alzheimer's disease (AD) is characterized by early degeneration of cholinergic neurons and decreased levels of nerve growth factor (NGF). Thus, increasing the NGF levels by for instance encapsulated cell bio-delivery (ECB) is a potential treatment strategy. The results from our previous first-in-human studies on ECB of NGF to the basal forebrain cholinergic neurons were promising, but indicated some variability of long-term viability of the encapsulated cells and associated reduced NGF-release. Here we studied the effect of amyloid beta-peptides (Aβ), interleukin 1-beta (IL-1β), and CSF from AD, Lewy body dementia (LBD) or subjective cognitive impairment (SCI) patients on the NGF overproducing cell line NGC-0295. At physiological concentrations, neither Aβ{sub 40} nor Aβ{sub 42} had any major impact on cell viability or NGF-production. In contrast, IL-1β dose-dependently affected NGF-production over time. Exposure of NGF-producing cells to CSF from AD patients showed significantly reduced NGF-release as compared to CSF from LBD or SCI patients. By mass spectrometry we found 3 proteins involved in inflammatory pathways to have an altered expression in AD CSF compared to LBD and SCI. Cell survival and NGF-release were not affected by Aβ. NGF-release was affected by IL-1β, suggesting that inflammation has a negative effect on ECB cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Electron microscopy techniques employed to explore mitochondrial defects in the developing rat brain following ketamine treatment

Ketamine, an FDA-approved N-methyl-D-aspartate (NMDA) receptor antagonist, is commonly used for general pediatric anesthesia. Accumulating evidence has indicated that prolonged exposure to ketamine induces widespread apoptotic cell death in the developing brains of experimental animals. Although mitochondria are known to play a pivotal role in cell death, little is known about the alterations in mitochondrial ultrastructure that occur during ketamine-induced neurotoxicity. The objective of this pilot study was to utilize classic and contemporary methods in electron microscopy to study the impact of ketamine on the structure of mitochondria in the developing rat brain. While transmission electron microscopy (TEM) was employed to comprehensively study mitochondrial inner membrane topology, serial block-face scanning electron microscopy (SBF-SEM) was used as a complementary technique to compare the overall mitochondrial morphology from a representative treated and untreated neuron. In this study, postnatal day 7 (PND-7) Sprague-Dawley rats were treated with ketamine or saline (6 subcutaneous injections × 20 mg/kg or 10 ml/kg, respectively, at 2-h intervals with a 6-h withdrawal period after the last injection, n=6 each group). Samples from the frontal cortex were harvested and analyzed using TEM or SBF-SEM. While classic TEM revealed that repeated ketamine exposure induces significant mitochondrial swelling in neurons, the newer technique of SBF-SEM confirmed the mitochondrial swelling in three dimensions (3D) and showed that ketamine exposure may also induce mitochondrial fission, which was not observable in the two dimensions (2D) of TEM. Furthermore, 3D statistical analysis of these reconstructed mitochondria appeared to show that ketamine-treated mitochondria had significantly larger volumes per unit surface area than mitochondria from the untreated neuron. The ultrastructural mitochondrial alterations demonstrated here by TEM and SBF-SEM support ketamine’s proposed mechanism of neurotoxicity in the developing rat brain.

60 APPLIED LIFE SCIENCES↗