Oxygen impairs oligodendroglial development via oxidative stress and reduced expression of HIF-1α

The premature increase of oxygen tension may contribute to oligodendroglial precursor cell (OPC) damage in preterm infants. Fetal OPCs are exposed to low oxygen tissue tensions not matched when cells are cultured in room air. Maturation (A2B5, O4, O1, MBP, CNP, arborization), oxidative stress (nitrotyrosine Western blot, NRF2 and SOD2 expression), apoptosis (TUNEL), proliferation (Ki67), and expression of transcription factors regulated by Hypoxia-Inducible-Factor-1-alpha (Hif-1α) expressed in OPCs (Olig1, Olig2, Sox9, Sox10) were assessed in rat OPCs and OLN93 cells cultured at 5% O2 and 21% O2. Influences of Hif-1α were investigated by Hif-1α luciferase reporter assays and Hif-1α-knockdown experiments. At 21% O2, cell proliferation was decreased and process arborization of OPCs was reduced. Expression of MBP, CNP, Olig1, Sox9 and Sox10 was lower at 21% O2, while Nrf2, SOD2, nitrotyrosine were increased. Apoptosis was unchanged. Luciferease reporter assay in OLN93 cells indicated increased Hif-1α activity at 5% O2. In OLN93 cells at 5% O2, Hif-1α knockdown decreased the expression of MBP and CNP, similar to that observed at 21% O2. These data indicate that culturing OPCs at 21% O2 negatively affects development and maturation. Both enhanced oxidative stress and reduced expression of Hif-1α-regulated genes contribute to these hyperoxia-induced changes

Postnatal myelination of the immature rat cingulum is regulated by GABAB receptor activity

Myelination of axons in the neonatal brain is a highly complex process primarily achieved by oligodendroglial cells (OLs). OLs express receptors for gamma-aminobutyric acid (GABA) which is released from cortical interneurons on a basal level, while glial cells can be a source of GABA, too. We investigated GABA-induced oligodendroglial maturation, proliferation, apoptosis, and myelin production after pharmacological inhibition of GABA(A) and GABA(B) in the neonatal rat brain. Daily injections of the reverse GABA(A) receptor agonist (DMCM) and the GABA(B) receptor antagonist (CGP35348) were performed from postnatal day 6 (P6) to P11. MBP expression was examined by Western blots and immunohistochemistry. Furthermore, we determined the number of CC1(+)OLIG2(+) and CNP(+)OLIG2(+) cells to assess maturation, the number of PCNA(+)OLIG2(+) oligodendrocytes to assess proliferation, the number of oligodendrocyte precursor cells (PDGFR alpha(+)OLIG2(+)), and apoptosis of OLs (CASP3A(+)OLIG2(+)) as well as apoptotic cells in total (CASP3A(+)DAPI(+)) at P11 and P15. In addition, we analyzed the expression Pdgfr alpha and CNP. MBP expression was significantly reduced after CGP treatment at P15. In the same animal group, CNP expression and CNP(+)OLIG2(+) cells decreased temporarily at P11. At P15, the proliferation of PCNA(+)OLIG2(+) cells and the number of PDGFR alpha(+)OLIG2(+) cells increased after GABA(B) receptor antagonization whereas no significant differences were visible in the Pdgfr alpha gene expression. No changes in apoptotic cell death were observed. CGP treatment induced a transient maturational delay at P11 and deficits in myelin expression at P15 with increased oligodendroglial proliferation. Our in vivo study indicates GABA(B) receptor activity as a potential modulator of oligodendroglial development

In vitro P38MAPK inhibition in aged astrocytes decreases reactive astrocytes, inflammation and increases nutritive capacity after oxygen-glucose deprivation

Envelliment; Astròcits; P38MAPKEnvejecimiento; Astrocitos; P38MAPKAgeing; Atrocytes; P38MAPKProper astroglial functioning is essential for the development and survival of neurons and oligodendroglia under physiologic and pathological circumstances. Indeed, malfunctioning of astrocytes represents an important factor contributing to brain injury. However, the molecular pathways of this astroglial dysfunction are poorly defined. In this work we show that aging itself can drastically perturb astrocyte viability with an increase of inflammation, cell death and astrogliosis. Moreover, we demonstrate that oxygen glucose deprivation (OGD) has a higher impact on nutritive loss in aged astrocytes compared to young ones, whereas aged astrocytes have a higher activity of the anti-oxidant systems. P38MAPK signaling has been identified to be upregulated in neurons, astrocytes and microglia after ischemic stroke. By using a pharmacological p38α specific inhibitor (PH-797804), we show that p38MAPK pathway has an important role in aged astrocytes for inflammatory and oxidative stress responses with the subsequent cell death that occurs after OGD.Deutsche Forschungsgemeinschaft (SCHE 2078/2-1). Förderverein für frühgeborene Kinder an der Charité e.V. Basque Government Postdoc (2017_1_0095)

In Vitro P38MAPK Inhibition in Aged Astrocytes Decreases Reactive Astrocytes, Inflammation and Increases Nutritive Capacity After Oxygen-Glucose Deprivation

Proper astroglial functioning is essential for the development and survival of neurons and oligodendroglia under physiologic and pathological circumstances. Indeed, malfunctioning of astrocytes represents an important factor contributing to brain injury. However, the molecular pathways of this astroglial dysfunction are poorly defined. In this work we show that aging itself can drastically perturb astrocyte viability with an increase of inflammation, cell death and astrogliosis. Moreover, we demonstrate that oxygen glucose deprivation (OGD) has a higher impact on nutritive loss in aged astrocytes compared to young ones, whereas aged astrocytes have a higher activity of the anti-oxidant systems. P38MAPK signaling has been identified to be upregulated in neurons, astrocytes and microglia after ischemic stroke. By using a pharmacological p38 alpha specific inhibitor (PH-797804), we show that p38MAPK pathway has an important role in aged astrocytes for inflammatory and oxidative stress responses with the subsequent cell death that occurs after OGD.Deutsche Forschungsgemeinschaft (SCHE 2078/2-1). Forderverein fur fruhgeborene Kinder an der Charite e.V. Basque Government Postdoc (2017_1_0095

A Narrative Review of Motor Competence in Children and Adolescents: What We Know and What We Need to Find Out

Lack of physical activity is a global public health problem causing not only morbidity and premature mortality, but it is also a major economic burden worldwide. One of the cornerstones of a physically active lifestyle is Motor Competence (MC). MC is a complex biocultural attribute and therefore, its study requires a multi-sectoral, multi-, inter- and transdisciplinary approach. MC is a growing area of research, especially in children and adolescents due to its positive association with a plethora of health and developmental outcomes. Many questions, however, remain to be answered in this field of research, with regard to: (i) Health and Developmental-related Associations of MC; (ii) Assessment of MC; (iii) Prevalence and Trends of MC; (iv) Correlates and Determinants of MC; (v) MC Interventions, and (vi) Translating MC Research into Practice and Policy. This paper presents a narrative review of the literature, summarizing current knowledge, identifying key research gaps and presenting questions for future investigation on MC in children and adolescents. This is a collaborative effort from the International Motor Competence Network (IMCNetwork) a network of academics and researchers aiming to promote international collaborative research and knowledge translation in the expansive field of MC. The knowledge and deliverables generated by addressing and answering the aforementioned research questions on MC presented in this review have the potential to shape the ways in which researchers and practitioners promote MC and physical activity in children and adolescents across the worl

Hyperoxia induced cerebellar injury in rats as model of brain injury in preterm infants

Former preterm infants often suffer from impaired postnatal brain development. In general, brain injury is reported to be caused by hypoxia/ischemia, infection/inflammation and hyperoxia. Due to recent insights, pathologies of the cerebellum can often be found, too. Preterm birth seems to be associated with a reduction of the cerebellar volume and decreased cell density in the cerebellar cortex. However, the mechanisms of cerebellar injuries are poorly understood. Directly after human birth, the arterial oxygen tension of the newborn increases by three- to fourfold. In preterm infants, the rise of oxygen concentration caused by premature birth into room air hits the immature cerebellum at a vulnerable phase of dynamic growth nearly unparalleled elsewhere in the brain with highly increased precursor proliferation. In this study, it was analyzed whether postnatal hyperoxia perturbs cerebellar growth and affects white matter and neuronal development. Newborn rats were exposed to 24 hours 80% O2 from postnatal day 6 (P6) to postnatal day 7 (P7) to mimic the sharp increase of oxygen tension. Cerebellar injury was analyzed by Magnetic Resonance Imaging, quantitative Real-time PCR, Western blot, ELISA and immunohistochemistry at the ages P7, P11 and P30. Hyperoxia resulted in a reduction of cerebellar volume together with long term white matter damage and impaired neuronal development. Decreased proliferation and increased cell death of oligodendroglial precursor cells led to a myelination deficit. A lack in granule cell survival and impaired granule cell precursor proliferation resulted in a long-term injury of cerebellar granule cells. Cerebellar injury was triggered by impaired astrocytic growth factor supply, as indicated by results of cell culture experiments and ex vivo analysis with a reduction of PDGFA and BDNF as important regulating factors. The affection of the cerebellar Purkinje cells by hyperoxia resulted in delayed development including impairment of dendrite growth and neuronal branching. Moreover, Purkinje cell SHH expression and GABA secretion were reduced by postnatal hyperoxia. In the cerebellum postnatal precursor proliferation is regulated by SHH. These results indicate that reduction of SHH expression contributed at least partially to the impaired precursor proliferation and that cerebellar morphogenesis is altered by the lower GABA level. Neonatal injury induced by hyperoxia alters the regulatory program of the postnatal cerebellar development by the inhibition of Purkinje cell function and the impairment of glial and neuronal crosstalk. As a conclusion, the maldevelopment of the cerebellum found in preterm infants can be caused by postnatal oxygen toxicity.Frühgeborene Kinder leiden im Laufe ihrer Entwicklung häufig an einer Störung der funktionellen und strukturellen Reifung des Gehirns. Diese Defizite werden im Allgemeinen durch Hypoxie/Ischämie, Infektionen und Endzündungen, aber auch durch Hyperoxie verursacht. Bei vielen unreif geborenen Kindern kommt es dabei auch zu einer Beeinträchtigung des Kleinhirns in Form einer Volumenreduktion und einer veränderten Zelldichte in der Kleinhirnrinde. Die Ursachen für diese Entwicklungsstörung sind kaum beschrieben. Als eine mögliche Ursache kommt eine Toxizität oder Dysregulation durch den zu früh eintreffenden Anstieg des arteriellen Sauerstoffpartialdrucks direkt nach der Geburt infrage. Zu diesem Zeitpunkt befindet sich das unreife Kleinhirn des Fötus bzw. von extrem frühgeborenen Kindern in einer Wachstumsphase, die in keiner anderen Hirnregion zu finden ist. Eine hohe Anzahl unreifer Vorläuferzellen zeigt eine hohe Proliferationsaktivität, unreife Vorläuferzellen sind gegenüber drastischen Umweltveränderungen sehr vulnerabel. Um den starken Anstieg des Sauerstoffangebots, der im Fötus bei Frühgeburt unter Raumluft auftreten kann, im experimentellen Modell zu imitieren, wurden neugeborene Ratten von Tag sechs bis Tag sieben nach der Geburt (P6 bis P7) mit 80% Sauerstoff inkubiert. Der sehr unreife Zustand des Gehirns wird in diesem Alter der Tiere oftmals verglichen mit der Unreife der Gehirne von extrem Frühgeborenen. In der aktuellen Studie im Hyperoxiemodell wurde eine Beeinträchtigung der Kleinhirnentwicklung mittels Magnetresonanztomographie, quantitativer Real Time PCR, Western Blot, ELISA und Immunhistochemie zu den Entwicklungszeitpunkten P7, P11 und P30 analysiert. Der Hauptfokus lag hierbei zum einen auf der Entwicklung der weißen Substanz und zum anderen auf der neuronalen Entwicklung der Kleinhirnrinde. Die neonatale Hyperoxie induzierte bei den Ratten eine Verminderung des Kleinhirnvolumens, die von einer andauernden Schädigung der weißen Substanz und einer gestörten Entwicklung der Kleinhirnneurone begleitet wurde. Durch eine verminderte Proliferationsrate und einem erhöhten Zelltod von Vorläuferzellen der für die Myelinisierung verantwortlichen Oligodendrozyten kam es zu einem signifikanten Myelinisierungsdefizit. Die erhöhte Apoptose von unreifen Körnerzellen sowie die verminderte Proliferation der Vorläufer der Körnerzellen führten zu einer dauerhaften Schädigung dieser neuronalen Population. Die gestörte Entwicklung des Kleinhirns wurde durch eine verminderte Expression von astrozytären Wachstumsfaktoren mit induziert. Die in vivo detektierte Reduktion von PDGFA und BDNF konnte in vitro, sowie ex vivo in Astrozyten bestätigt werden. Die zusätzlich verzögerte Reifung der Purkinjezellen, mit einer gestörten neuronalen Verzweigung und einem verzögerten Auswuchs der Dendriten, führte zu einer verminderten Expression von SHH sowie einer reduzierten Sekretion von GABA. Zu diesem Entwicklungszeitpunkt wird die Proliferation von Vorläuferzellen im Kleinhirn von SHH stimuliert. Die verminderte Expression von SHH konnte demnach mit der gestörten Proliferation der Vorläuferzellen in Verbindung gebracht werden. Zusätzlich kann die allgemeine Entwicklung des Kleinhirns durch die reduzierte GABA-Konzentration beeinträchtigt worden sein. Die durch Hyperoxie induzierte Schädigung hemmt die Funktion der Purkinjezellen und stört die Interaktion von Gliazellen und Neuronen. Sauerstoff kann demnach eine Ursache der gestörten Kleinhirnentwicklung bei sehr unreifen Frühgeborenen sein

Die Schädigung des unreifen Kleinhirns durch Hyperoxie in Ratten als Modell der Hirnschädigung bei Frühgeborenen

Former preterm infants often suffer from impaired postnatal brain development. In general, brain injury is reported to be caused by hypoxia/ischemia, infection/inflammation and hyperoxia. Due to recent insights, pathologies of the cerebellum can often be found, too. Preterm birth seems to be associated with a reduction of the cerebellar volume and decreased cell density in the cerebellar cortex. However, the mechanisms of cerebellar injuries are poorly understood. Directly after human birth, the arterial oxygen tension of the newborn increases by three- to fourfold. In preterm infants, the rise of oxygen concentration caused by premature birth into room air hits the immature cerebellum at a vulnerable phase of dynamic growth nearly unparalleled elsewhere in the brain with highly increased precursor proliferation. In this study, it was analyzed whether postnatal hyperoxia perturbs cerebellar growth and affects white matter and neuronal development. Newborn rats were exposed to 24 hours 80% O2 from postnatal day 6 (P6) to postnatal day 7 (P7) to mimic the sharp increase of oxygen tension. Cerebellar injury was analyzed by Magnetic Resonance Imaging, quantitative Real-time PCR, Western blot, ELISA and immunohistochemistry at the ages P7, P11 and P30. Hyperoxia resulted in a reduction of cerebellar volume together with long term white matter damage and impaired neuronal development. Decreased proliferation and increased cell death of oligodendroglial precursor cells led to a myelination deficit. A lack in granule cell survival and impaired granule cell precursor proliferation resulted in a long-term injury of cerebellar granule cells. Cerebellar injury was triggered by impaired astrocytic growth factor supply, as indicated by results of cell culture experiments and ex vivo analysis with a reduction of PDGFA and BDNF as important regulating factors. The affection of the cerebellar Purkinje cells by hyperoxia resulted in delayed development including impairment of dendrite growth and neuronal branching. Moreover, Purkinje cell SHH expression and GABA secretion were reduced by postnatal hyperoxia. In the cerebellum postnatal precursor proliferation is regulated by SHH. These results indicate that reduction of SHH expression contributed at least partially to the impaired precursor proliferation and that cerebellar morphogenesis is altered by the lower GABA level. Neonatal injury induced by hyperoxia alters the regulatory program of the postnatal cerebellar development by the inhibition of Purkinje cell function and the impairment of glial and neuronal crosstalk. As a conclusion, the maldevelopment of the cerebellum found in preterm infants can be caused by postnatal oxygen toxicity

Glial Factors Regulating White Matter Development and Pathologies of the Cerebellum.

The cerebellum is a brain region that undergoes extremely dynamic growth during perinatal and postnatal development which is regulated by the proper interaction between glial cells and neurons with a complex concert of growth factors, chemokines, cytokines, neurotransmitters and transcriptions factors. The relevance of cerebellar functions for not only motor performance but also for cognition, emotion, memory and attention is increasingly being recognized and acknowledged. Since perturbed circuitry of cerebro-cerebellar trajectories can play a role in many central nervous system pathologies and thereby contribute to neurological symptoms in distinct neurodevelopmental and neurodegenerative diseases, is it the aim with this mini-review to highlight the pathways of glia–glia interplay being involved. The designs of future treatment strategies may hence be targeted to molecular pathways also playing a role in development and disease of the cerebellum

Antioxidative effects of caffeine in a hyperoxia-based rat model of bronchopulmonary dysplasia

Abstract Background While additional oxygen supply is often required for the survival of very premature infants in intensive care, this also brings an increasing risk of progressive lung diseases and poor long-term lung outcomes. Caffeine is administered to neonates in neonatal intensive care for the prevention and treatment of apneas and has been shown to reduce BPD incidence and the need for mechanical ventilation, although it is still unclear whether this is due to a direct pulmonary action via antagonism of adenosine receptors and/or an indirect action. This experimental study aims to investigate the action of caffeine on the oxidative stress response in pulmonary tissue in a hyperoxia-based model of bronchopulmonary dysplasia in newborn rats. Methods Newborn Wistar rats were exposed to 21% or 80% oxygen for 3 (P3) or 5 (P5) postnatal days with or without recovery on room air until postnatal day 15 (P15) and treated with vehicle or caffeine (10 mg/kg) every 48 h beginning on the day of birth. The lung tissue of the rat pups was examined for oxidative stress response at P3 and P5 immediately after oxygen exposure or after recovery in ambient air (P15) by immunohistological staining and analysis of lung homogenates by ELISA and qPCR. Results Lungs of newborn rats, corresponding to the saccular stage of lung development and to the human lung developmental stage of preterms, showed increased rates of total glutathione and hydrogen peroxide, oxidative damage to DNA and lipids, and induction of second-phase mediators of antioxidative stress response (superoxide dismutase, heme oxygenase-1, and the Nrf2/Keap1 system) in response to hyperoxia. Caffeine reduced oxidative DNA damage and had a protective interference with the oxidative stress response. Conclusion In addition to the pharmacological antagonism of adenosine receptors, caffeine appears to be a potent antioxidant and modulates the hyperoxia-induced pulmonary oxidative stress response and thus protective properties in the BPD-associated animal model. Free-radical-induced damage caused by oxidative stress seems to be a biological mechanism progress of newborn diseases. New aspects of antioxidative therapeutic strategies to passivate oxidative stress-related injury should be in focus of further investigations

GABAB Receptor-Mediated Impairment of Intermediate Progenitor Maturation During Postnatal Hippocampal Neurogenesis of Newborn Rats

The neurotransmitter GABA and its receptors assume essential functions during fetal and postnatal brain development. The last trimester of a human pregnancy and early postnatal life involves a vulnerable period of brain development. In the second half of gestation, there is a developmental shift from depolarizing to hyperpolarizing in the GABAergic system, which might be disturbed by preterm birth. Alterations of the postnatal GABA shift are associated with several neurodevelopmental disorders. In this in vivo study, we investigated neurogenesis in the dentate gyrus (DG) in response to daily administration of pharmacological GABAA (DMCM) and GABAB (CGP 35348) receptor inhibitors to newborn rats. Six-day-old Wistar rats (P6) were daily injected (i.p.) to postnatal day 11 (P11) with DMCM, CGP 35348, or vehicle to determine the effects of both antagonists on postnatal neurogenesis. Due to GABAB receptor blockade by CGP 35348, immunohistochemistry revealed a decrease in the number of NeuroD1 positive intermediate progenitor cells and a reduction of proliferative Nestin-positive neuronal stem cells at the DG. The impairment of hippocampal neurogenesis at this stage of differentiation is in line with a significantly decreased RNA expression of the transcription factors Pax6, Ascl1, and NeuroD1. Interestingly, the number of NeuN-positive postmitotic neurons was not affected by GABAB receptor blockade, although strictly associated transcription factors for postmitotic neurons, Tbr1, Prox1, and NeuroD2, displayed reduced expression levels, suggesting impairment by GABAB receptor antagonization at this stage of neurogenesis. Antagonization of GABAB receptors decreased the expression of neurotrophins (BDNF, NT-3, and NGF). In contrast to the GABAB receptor blockade, the GABAA receptor antagonization revealed no significant changes in cell counts, but an increased transcriptional expression of Tbr1 and Tbr2. We conclude that GABAergic signaling via the metabotropic GABAB receptor is crucial for hippocampal neurogenesis at the time of rapid brain growth and of the postnatal GABA shift. Differentiation and proliferation of intermediate progenitor cells are dependent on GABA. These insights become more pertinent in preterm infants whose developing brains are prematurely exposed to spostnatal stress and predisposed to poor neurodevelopmental disorders, possibly as sequelae of early disruption in GABAergic signaling