Janc, Oliwia A.

[["dc.bibliographiccitation.artnumber","56"],["dc.bibliographiccitation.journal","Frontiers in Cellular Neuroscience"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Janc, Oliwia A."],["dc.contributor.author","Müller, Michael"],["dc.date.accessioned","2018-09-28T10:14:12Z"],["dc.date.available","2018-09-28T10:14:12Z"],["dc.date.issued","2014"],["dc.description.abstract","Rett syndrome (RS) causes severe cognitive impairment, loss of speech, epilepsy, and breathing disturbances with intermittent hypoxia. Also mitochondria are affected; a subunit of respiratory complex III is dysregulated, the inner mitochondrial membrane is leaking protons, and brain ATP levels seem reduced. Our recent assessment of mitochondrial function in MeCP2 (methyl-CpG-binding protein 2)-deficient mouse (Mecp2 (-) (/y)) hippocampus confirmed early metabolic alterations, an increased oxidative burden, and a more vulnerable cellular redox balance. As these changes may contribute to the manifestation of symptoms and disease progression, we now evaluated whether free radical scavengers are capable of improving neuronal and mitochondrial function in RS. Acute hippocampal slices of adult mice were incubated with the vitamin E derivative Trolox for 3-5 h. In Mecp2 (-) (/y) slices this treatment dampened neuronal hyperexcitability, improved synaptic short-term plasticity, and fully restored synaptic long-term potentiation (LTP). Furthermore, Trolox specifically attenuated the increased hypoxia susceptibility of Mecp2 (-) (/y) slices. Also, the anticonvulsive effects of Trolox were assessed, but the severity of 4-aminopyridine provoked seizure-like discharges was not significantly affected. Adverse side effects of Trolox on mitochondria can be excluded, but clear indications for an improvement of mitochondrial function were not found. Since several ion-channels and neurotransmitter receptors are redox modulated, the mitochondrial alterations and the associated oxidative burden may contribute to the neuronal dysfunction in RS. We confirmed in Mecp2 (-) (/y) hippocampus that Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves the hypoxia tolerance. Therefore, radical scavengers are promising compounds for the treatment of neuronal dysfunction in RS and deserve further detailed evaluation."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2014"],["dc.identifier.doi","10.3389/fncel.2014.00056"],["dc.identifier.pmid","24605086"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9944"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15854"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.rights","CC BY 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/3.0"],["dc.title","The free radical scavenger Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves hypoxia tolerance in a mouse model of Rett syndrome"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","53"],["dc.bibliographiccitation.journal","Frontiers in Pharmacology"],["dc.bibliographiccitation.volume","3"],["dc.contributor.author","Schnell, Christian"],["dc.contributor.author","Janc, Oliwia A."],["dc.contributor.author","Kempkes, Belinda"],["dc.contributor.author","Araya Callis, Carolina"],["dc.contributor.author","Flügge, Gabriele"],["dc.contributor.author","Hülsmann, Swen"],["dc.contributor.author","Müller, Michael"],["dc.date.accessioned","2018-09-28T10:22:20Z"],["dc.date.available","2018-09-28T10:22:20Z"],["dc.date.issued","2012"],["dc.description.abstract","Chronic stress affects neuronal networks by inducing dendritic retraction, modifying neuronal excitability and plasticity, and modulating glial cells. To elucidate the functional consequences of chronic stress for the hippocampal network, we submitted adult rats to daily restraint stress for 3 weeks (6 h/day). In acute hippocampal tissue slices of stressed rats, basal synaptic function and short-term plasticity at Schaffer collateral/CA1 neuron synapses were unchanged while long-term potentiation was markedly impaired. The spatiotemporal propagation pattern of hypoxia-induced spreading depression episodes was indistinguishable among control and stress slices. However, the duration of the extracellular direct current potential shift was shortened after stress. Moreover, K(+) fluxes early during hypoxia were more intense, and the postsynaptic recoveries of interstitial K(+) levels and synaptic function were slower. Morphometric analysis of immunohistochemically stained sections suggested hippocampal shrinkage in stressed rats, and the number of cells that are immunoreactive for glial fibrillary acidic protein was increased in the CA1 subfield indicating activation of astrocytes. Western blots showed a marked downregulation of the inwardly rectifying K(+) channel Kir4.1 in stressed rats. Yet, resting membrane potentials, input resistance, and K(+)-induced inward currents in CA1 astrocytes were indistinguishable from controls. These data indicate an intensified interstitial K(+) accumulation during hypoxia in the hippocampus of chronically stressed rats which seems to arise from a reduced interstitial volume fraction rather than impaired glial K(+) buffering. One may speculate that chronic stress aggravates hypoxia-induced pathophysiological processes in the hippocampal network and that this has implications for the ischemic brain."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2012"],["dc.identifier.doi","10.3389/fphar.2012.00053"],["dc.identifier.pmid","22470344"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/7501"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15856"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.relation.eissn","1663-9812"],["dc.rights","CC BY-NC 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/3.0"],["dc.title","Restraint Stress Intensifies Interstitial K(+) Accumulation during Severe Hypoxia"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","266"],["dc.bibliographiccitation.journal","Frontiers in Cellular Neuroscience"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Janc, Oliwia A."],["dc.contributor.author","Hüser, Marc A."],["dc.contributor.author","Dietrich, Katharina"],["dc.contributor.author","Kempkes, Belinda"],["dc.contributor.author","Menzfeld, Christiane"],["dc.contributor.author","Hülsmann, Swen"],["dc.contributor.author","Müller, Michael"],["dc.date.accessioned","2018-09-28T09:49:07Z"],["dc.date.available","2018-09-28T09:49:07Z"],["dc.date.issued","2016"],["dc.description.abstract","Rett syndrome (RTT) is a severe neurodevelopmental disorder typically arising from spontaneous mutations in the X-chromosomal methyl-CpG binding protein 2 (MECP2) gene. The almost exclusively female Rett patients show an apparently normal development during their first 6-18 months of life. Subsequently, cognitive- and motor-impairment, hand stereotypies, loss of learned skills, epilepsy and irregular breathing manifest. Early mitochondrial impairment and oxidative challenge are considered to facilitate disease progression. Along this line, we recently confirmed in vitro that acute treatment with the vitamin E-derivative Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, ameliorates cellular redox balance and improves hypoxia tolerance in male MeCP2-deficient (Mecp2-/y ) mouse hippocampus. Pursuing these promising findings, we performed a preclinical study to define the merit of systemic Trolox administration. Blinded, placebo-controlled in vivo treatment of male mice started at postnatal day (PD) 10-11 and continued for ~40 days. Compounds (vehicle only, 10 mg/kg or 40 mg/kg Trolox) were injected intraperitoneally every 48 h. Detailed phenotyping revealed that in Mecp2-/y mice, blood glucose levels, lipid peroxidation, synaptic short-term plasticity, hypoxia tolerance and certain forms of environmental exploration were improved by Trolox. Yet, body weight and size, motor function and the rate and regularity of breathing did not improve. In conclusion, in vivo Trolox treatment partially ameliorated a subset of symptoms of the complex Rett phenotype, thereby confirming a partial merit of the vitamin E-derivative based pharmacotherapy. Yet, it also became evident that frequent animal handling and the route of drug administration are critical issues to be optimized in future trials."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2016"],["dc.identifier.doi","10.3389/fncel.2016.00266"],["dc.identifier.pmid","27895554"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/13968"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15847"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","Systemic Radical Scavenger Treatment of a Mouse Model of Rett Syndrome: Merits and Limitations of the Vitamin E Derivative Trolox"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]