Cerebral Palsy

Preconditioning protects endothelial cells as well as neurons from ischemic injury. In 7-d-old rat pups, ligating the carotid artery 1 h before hypoxia damaged the ipsilateral cerebral hemisphere; in contrast, ligating the artery 24 h before hypoxia provided complete neuroprotection. The protective effect of the 24 h artery ligation preconditioning model requires the activation of cAMP response element-binding protein (CREB). We tested the hypothesis that vascular endothelial growth factor (VEGF)-A/VEGF receptor-2 (VEGFR-2) signaling that leads to CREB activation is the shared pathway underlying the protective effect of preconditioning in neurons and endothelial cells. VEGF-A, VEGFR-1, or VEGFR-2 was inhibited by antisense oligodeoxynucleotides (ODNs) in vivo and by a VEGF-A neutralizing antibody or VEGFR-2 inhibitor in vitro. CREB phosphorylation (pCREB) and VEGF-A and VEGFR-2 expression were increased and colocalized in vascular endothelial cells and neurons in the ipsilateral cerebral cortex 24 h after ligation. The antisense ODN blockades of VEGF-A and VEGFR-2 decreased pCREB and reduced the protection of 24 h ligation preconditioning. Furthermore, oxygen-glucose deprivation (OGD) preconditioning upregulated VEGF-A, VEGFR-2, and pCREB levels and protected immortalized H19-7 neuronal cells and b.End3 vascular endothelial cells against 24 h OGD cell death. Blocking VEGF-A or VEGFR-2 reduced CREB activation and the effects of OGD preconditioning in neuronal cells and endothelial cells. Transfecting a serine-133 phosphorylation mutant CREB also inhibited the protective effect of OGD preconditioning. We conclude that VEGF-A/VEGFR-2 signaling leading to CREB phosphorylation is the shared pathway underlying the preconditioning-induced protective effect in neurons and vascular endothelial cells in the developing brain.

Copper deficiency is associated with impaired brain development and mitochondrial dysfunction. Perinatal copper deficiency was produced in Holtzman rats. In vivo proton NMR spectroscopy was used to quantify 18 cerebellar and hippocampal metabolites on postnatal day 21 (P21). Copper status was evaluated in male copper-adequate (CuA) and copper-deficient (CuD) brothers at P19 and at P23, 2 days following NMR experiments, by metal and in vitro metabolite data. Compared to CuA pups, CuD pups had lower ascorbate concentration in both brain regions, confirming prior HPLC data. Both regions of CuD rats also had lower N-acetylaspartate levels consistent with delayed development or impaired mitochondrial function similar to prior work demonstrating elevated lactate and citrate. For other metabolites, the P21 neurochemical profile of CuD rats was remarkably similar to CuA rats but uniquely different from iron-deficient or chronic hypoxia models. Further research is needed to determine the neurochemical consequences of copper deficiency.

Hypoxia-ischemia constitutes a risk in infants by altering cerebral blood flow regulatory mechanisms and causing loss of cerebral vascular auto-regulation. Hypotension, cerebral ischemia, and reperfusion are the main events involved in vascular auto-regulation leading to cell death and tissue damage. Reperfusion could be critical since organ damage, particularly of the brain, may be amplified during this period. An exaggerated activation of vasoactive agents of calcium mediated effects could be responsible for reperfusion injury, which, in turns, leads to cerebral hemorrhage and damage. These dramatic phenomena represent a common repertoire in infants complicated by perinatal acute or chronic hypoxia or cardiovascular disorders treated by risky procedures such as open heart surgery and cardiopulmonary by-pass (CPB). To date, despite accurate perinatal and intra-operative monitoring, the post-insult period is crucial, since clinical symptoms and monitoring parameters may be of no avail and therapeutic window for pharmacological intervention (6-12 hours) may be limited, at a time when brain damage is already occurring. Therefore, the measurement of circulating biochemical markers of brain damage, such as vasoactive agents and nervous tissue peptides is eagerly awaited in clinical practice to detect high risk infants. The present review is aimed at investigating the role as circulating biochemical markers such as adrenomedullin, a vasoactive peptide; S100B, a calcium binding protein, activin A, a glycoprotein; neuronal specific enolase (NSE), a dimeric isoenzyme; glial fibrillary acid protein (GFAP), a astroglial protein, in the cascade of events leading to ischemia reperfusion injury in infants complicated by perinatal asphyxia or cardiovascular disorders requiring risky therapeutic strategies such as CPB and/or extracorporeal membrane oxygenation.

The existence of a primitive, elemental form of CNS arousal, “generalized arousal,” has been hypothesized; it has been given an operational definition, and a high throughput assay has been assayed for it in mice. Many of the ascending and descending neuroanatomical pathways are fairly well understood. To begin experiments that might have potential implications for therapeutic measures, mice were rendered anoxic and it was shown that the assay can demonstrate behavioral abnormalities not detected with a standard neurological screen. These behavioral deficiencies are reminiscent of “sundowning,” a form of dementia seen in hospitalized elderly patients. Electrical stimulation of neurons in medial thalamic cell groups can increase activity in the generalized arousal assay. Current studies include attempts to achieve temporal patterns of electrical stimulation that would take advantage of nonlinear properties of ascending arousal pathways.

Several protein phosphatases are involved in neuroprotection in response to ischemic brain injury. Here, we report that reactive oxygen species (ROS)-mediated oxidative stress promotes phosphorylation of endogenous SHP-2 through lipid rafts in rat primary astrocytes. SHP-2 was transiently phosphorylated during hypoxia/reoxygenation, an effect abrogated by a ROS scavenger and an NADPH oxidase inhibitor. Additionally, exogenous treatment with hydrogen peroxide (H(2)O(2)) triggered SHP-2 phosphorylation in a time- and dose-dependent manner and led to its translocation into lipid rafts. H(2)O(2)-mediated SHP-2 phosphorylation and translocation were inhibited by filipin III and methyl-beta-cyclodextrin (MCD), lipid-raft-disrupting agents. In the presence of H(2)O(2), SHP-2 formed a complex with STAT-3 and reduced the steady-state STAT-3 phosphorylation level. Interestingly, the effect of H(2)O(2) on SHP-2 phosphorylation was cell-type specific. Remarkably, SHP-2 phosphorylation was induced strongly by H(2)O(2) in astrocytes, but barely detectable in microglia. Our results collectively indicate that SHP-2 is activated by ROS-mediated oxidative stress in astrocytes and functions as a component of the raft-mediated signaling pathway that acts through dephosphorylation and inactivation of other phosphotyrosine proteins, such as STAT-3.

Neuroblasts produced by the neural stem cells of the adult subventricular zone (SVZ) migrate into damaged brain areas after stroke or other brain injuries, and previous data have suggested that they generate regionally appropriate new neurons. To classify the types of neurons produced subsequent to ischemic injury, we combined BrdU or virus labeling with multiple neuronal markers to characterize new cells at different times after the induction of stroke. We show that SVZ neuroblasts give rise almost exclusively to calretinin-expressing cells in the damaged striatum, resulting in the accumulation of these cells during long term recovery after stroke. The vast majority of SVZ neuroblasts as well as newly born young and mature neurons in the damaged striatum constitutively express the transcription factor Sp8, but do not express transcription factors characteristic of medium-sized spiny neurons, the primary striatal projection neurons lost after stroke. Our results suggest that adult neuroblasts do not alter their intrinsic differentiation potential after brain injury.

Although some of the COX-2 metabolites and prostaglandins have been implicated in stroke and excitotoxicity, the role of prostaglandin F(2alpha) (PGF(2alpha)) and its FP receptor have not been elucidated in the pathogenesis of ischemic-reperfusion (I/R) brain injury. Here we investigated the FP receptor's contribution in a unilateral middle cerebral artery (MCA) occlusion model of focal cerebral ischemia in mice. The MCA in wild type (WT) and FP knockout (FP(-/-)) C57BL/6 male mice was transiently occluded with a monofilament for 90 min. After 96 h of reperfusion, the FP(-/-) mice had 25.3% less neurological deficit (P < 0.05) and 34.4% smaller infarct volumes (P < 0.05) than those of the WT mice. In a separate cohort, physiological parameters were monitored before, during, and after ischemia, and the results revealed no differences between the groups. Because excitotoxicity is an acute mediator of stroke outcome, the effect of acute NMDA-induced neurotoxicity was also tested. Forty-eight hours after unilateral intrastriatal NMDA injection, excitotoxic brain damage was 20.8% less extensive in the FP(-/-) mice (P < 0.05) than in the WT counterparts, further supporting the toxic contribution of the FP receptor in I/R injury. Additionally, we investigated the effect of post-treatment with the FP agonist latanoprost in mice subjected to MCA occlusion; such treatment resulted in an increase in neurological deficit and infarct size in WT mice (P < 0.05), though no effects were observed in the latanoprost-treated FP(-/-) mice. Together, the results suggest that the PGF(2alpha) FP receptor significantly enhances cerebral ischemic and excitotoxic brain injury and that these results are of importance when planning for potential development of therapeutic drugs to treat stroke and its acute and/or long term consequences.

Oligodendrocytes are sensitive to ischemic damage. The Sonic hedgehog (Shh) pathway is critical in oligodendrogenesis; Gli1 is the principal effector of Shh signaling. We investigated oligodendrogenesis and Shh/Gli1 pathway activation after bone marrow stromal cell (BMSC) treatment of stroke in rats. Rats were subjected to the middle cerebral artery occlusion (MCAo). BMSCs have been shown to promote functional recovery post stroke. A therapeutic dose of BMSC (3 x 10(6) cells) treatment was initiated 1 day after MCAo. Immunohistochemistry was carried out to measure the oligodendrocyte progenitor cells, oligodendrocytes, myelin, and expressions of Shh and Gli1 at 14 days after MCAo. Gene expression of Shh and Gli1 was tested at 2 days after MCAo. An in vitro study was used to investigate the effects of BMSC on a premature oligodendrocyte cell line (N20.1 cells). BMSC treatment significantly increased O4(+) oligodendrocytes, MBP(+) area, and bromodeoxyuridine (BrdU)(+), NG2(+), BrdU(+)-NG2(+) cells, and mRNA and protein expressions of Shh and Gli1 in the ipsilateral brain of the MCAo rats than that in phosphate buffered saline (PBS)-treated rats. BMSCs promoted N20.1 cell proliferation and Gli1 mRNA expression, and these effects were abolished by the Shh pathway inhibitor cyclopamine. These data indicate that the BMSC treatment stimulates oligodendrogenesis by activation of the Shh/Gli1 pathway post stroke.Journal of Cerebral Blood Flow & Metabolism advance online publication, 22 April 2009; doi:10.1038/jcbfm.2009.41.

Cilostazol, an antiplatelet drug used to treat intermittent claudication, has been reported to offer neuroprotection and endothelial protection in animals with ischemic brain injury. Here, we evaluated the protection afforded by cilostazol against ischemic brain injury and hemorrhagic transformation. Mice subjected to a 2-h filamental middle cerebral artery (MCA) occlusion were treated with cilostazol (10mg/kg, intraperitoneally just after the occlusion) or with vehicle. Histological outcomes (infarct volume and hemorrhagic transformation) and Evans blue extravasation were assessed after reperfusion. Mean infarct volume, hemorrhagic transformation, and Evans blue extravasation were all significantly reduced in the cilostazol-treated group. Thus, cilostazol protected against ischemic brain injury and hemorrhagic transformation in mice subjected to transient focal cerebral ischemia.

BackgroundInsular cortex (Ic) has been suggested to be a key site in limbic-autonomic integration. Association of Ic damage with disruption of diurnal blood pressure (BP) variation and higher serum level of noradrenaline has been reported. We examined the relationships of Ic volume with ambulatory BP measures and noradrenaline concentration.MethodsAmbulatory BP monitoring and brain magnetic resonance imaging (MRI) were performed in 55 elderly never-treated hypertensives. Ic volumes were measured using an intensity contour mapping algorithm. Serum adrenaline and noradrenaline concentrations were evaluated.ResultsSubjects were classified into an Ic-atrophy group (n = 14) and non-Ic-atrophy group (n = 41) based on a total Ic volume (left and right side) of 12.6 cm(3) (lowest quartile). In the Ic-atrophy group, 24 h (145 mm Hg vs. 134 mm Hg, P < 0.05) and sleep (143 mm Hg vs. 127 mm Hg, P < 0.01) systolic BP (SBP) and nocturnal SBP dipping (1.30% vs. 8.54%, P < 0.05) were significantly different, and noradrenaline (373 pg/ml vs. 296 pg/ml, P = 0.08) was marginally different from those in the non-Ic-atrophy group. Left Ic volume was significantly correlated with 24 h (r = -0.277) and sleep (r = -0.499) SBP and nocturnal SBP dipping (r = 0.413), while right Ic volume was significantly correlated with 24 h (r = -0.261) and sleep (r = -0.430) SBP, nocturnal SBP dipping (r = 0.321) and noradrenaline (r = -0.335). In multiple linear regression analysis adjusted for age, gender and body mass index (BMI), left Ic volume was significantly negatively associated with sleep SBP (P < 0.01) and positively with nocturnal SBP dipping (P < 0.05).ConclusionIc atrophy, specifically in the left side, may partly contribute to disruption of diurnal ambulatory BP rhythm via central autonomic nervous system (ANS) dysregulation.American Journal of Hypertension 2009; doi:10.1038/ajh.2009.71American Journal of Hypertension 2009; doi:10.1038/ajh.2009.71.