Animal models of hypoxic-ischemic brain damage in the newborn

Proteomic changes of the bilateral M1 and spinal cord in hemiplegic cerebral palsy mouse: Effects of constraint-induced movement therapy

Hemiplegic cerebral palsy (HCP) is a non-progressive movement and posture disorder that affects one side of the body. Constraint-induced movement therapy (CIMT) can improve the hand function of children with HCP. We used label-free proteomic quantification technology to evaluate proteomic changes in the bilateral M1 and spinal cord in HCP mouse induced by hypoxia/ischemia and CIMT. Nissl staining showed reduced neuron density in the HCP mice's lesioned and contralesional M1. The rotarod test and grip strength test showed motor dysfunction in mice with HCP and improved motor ability after CIMT. A total of 5147 proteins were identified. Fifty-one, five, and sixty common differentially expressed proteins (DEPs), which were co-regulated by HCP and CIMT, were found in the lesioned M1, the contralesional M1 and the spinal cord respectively. The significant proteins included alpha-centractin, metaxin complex, PKC, septin 11, choline transporter-like proteins, protein 4.1, teneurin-4, and so on, which mainly related to synapse stability, neuronal development and maintenance, axon development, and myelin formation. The KEGG pathways of HCP-induced DEPs mainly related to lipid metabolism, synaptic remodeling, SNARE interactions in vesicular transport and axon formation. The CIMT-induced DEPs were mainly related to synaptic remodeling and axon formation in the lesioned M1 and spinal cord. This study investigated the proteomic changes of the bilateral M1 and spinal cord as well as the CIMT-induced proteomic changes in HCP mice, which might provide new insights into the therapy of HCP.

An Inexpensive Open-Source Chamber for Controlled Hypoxia/Hyperoxia Exposure

Understanding hypoxia/hyperoxia exposure requires either a high-altitude research facility or a chamber in which gas concentrations are precisely and reproducibly controlled. Hypoxia-induced conditions such as hypoxic-ischemic encephalopathy (HIE), obstructive or central apneas, and ischemic stroke present unique challenges for the development of models with acute or chronic hypoxia exposure. Many murine models exist to study these conditions; however, there are a variety of different hypoxia exposure protocols used across laboratories. Experimental equipment for hypoxia exposure typically includes flow regulators, nitrogen concentrators, and premix oxygen/nitrogen tanks. Commercial hypoxia/hyperoxia chambers with environmental monitoring are incredibly expensive and require proprietary software with subscription fees or highly expensive software licenses. Limitations exist in these systems as most are single animal systems and not designed for extended or intermittent hypoxia exposure. We have developed a simple hypoxia chamber with off-the-shelf components, and controlled by open-source software for continuous data acquisition of oxygen levels and other environmental factors (temperature, humidity, pressure, light, sound, etc.). Our chamber can accommodate up to two mouse cages and one rat cage at any oxygen level needed, when using a nitrogen concentrator or premixed oxygen/nitrogen tank with a flow regulator, but is also scalable. Our system uses a Python-based script to save data in a text file using modules from the sensor vendor. We utilized Python or R scripts for data analysis, and we have provided examples of data analysis scripts and acquired data for extended exposure periods (≤7 days). By using FLOS (Free-Libre and open-source) software and hardware, we have developed a low-cost and customizable system that can be used for a variety of exposure protocols. This hypoxia/hyperoxia exposure chamber allows for reproducible and transparent data acquisition and increased consistency with a high degree of customization for each experimenter’s needs.

Treatments and therapeutic protocols for the recovery of an asphyxiated new-born: A review of pre-clinical and clinical studies in human neonates and in different animal models

The objective of this review is to ascertain the advantages and disadvantages of several treatments and therapeutic protocols that have been used for the prevention and treatment of perinatal asphyxia in human neonates and in different animal models. Perinatal asphyxia is one of the main causes of mortality worldwide and is an important factor in triggering physio-metabolic disorders that result in serious neurological consequences and learning disorders not only in human foetuses and neonates, but also in animals. In recent years, the search for new pharmacological protocols to prevent and reverse physio-metabolic disorders and brain damage derived from perinatal asphyxia has been and continues to be the subject of intense research. Currently, within these pharmacological protocols, therapeutic strategies have been evaluated that use respiratory and hormonal stimulants, as well as hypothermic therapies in combination with other putative neuroprotective agents. Similarly, energy supplements have been evaluated with the objective of preventing perinatal asphyxia and treating new-borns with this condition, and to decrease the incidence of neonatal and foetal deaths associated with it. However, despite these promising advances, this pathology has persisted, since the administration of these therapies in low doses may not exert a neuroprotective effect or, in high doses, can trigger adverse effects (such as reduced cardiac contractility, reduced cerebral blood flow, poor perfusion, sympathetic and neuroendocrine stimulation, and increased blood viscosity) in human foetuses and neonates as well as in different animal models (rats, piglets, sheep and rabbits). Therefore, it is important to determine the minimum effective dose with which these therapies exert a neuroprotective effect, as well as the mode of administration, the duration of therapy, etc. Therefore, until a powerful strategy is found to improve the consequences of suffocation, this topic will continue to be the subject of intensive research in the future.

Constraint-Induced Movement Therapy Promotes Neural Remodeling and Functional Reorganization by Overcoming Nogo-A/NgR/RhoA/ROCK Signals in Hemiplegic Cerebral Palsy Mice

Background. Little is known about the induction of functional and brain structural reorganization in hemiplegic cerebral palsy (HCP) by constraint-induced movement therapy (CIMT). Objective. We aimed to explore the specific molecular mechanism of functional and structural plasticity related to CIMT in HCP. Methods. The mice were divided into a control group and HCP groups with different interventions (unconstraint-induced movement therapy [UNCIMT], CIMT or siRNA-Nogo-A [SN] treatment): the HCP, HCP+UNCIMT, HCP+CIMT, HCP+SN, and HCP+SN+CIMT groups. Rotarod and front-limb suspension tests, immunohistochemistry, Golgi-Cox staining, transmission electron microscopy, and Western blot analyses were applied to measure motor function, neurons and neurofilament density, dendrites/axon areas, myelin integrity, and Nogo-A/NgR/RhoA/ROCK expression in the motor cortex. Results. The mice in the HCP+CIMT group had better motor function, greater neurons and neurofilament density, dendrites/axon areas, myelin integrity, and lower Nogo-A/NgR/RhoA/ROCK expression in the motor cortex than the HCP and HCP+UNCIMT groups (P < .05). Moreover, the expression of Nogo-A/NgR/RhoA/ROCK, the improvement of neural remodeling and motor function of mice in the HCP+SN group were similar to those in the HCP+CIMT group (P > .05). The neural remodeling and motor function of the HCP+SN+CIMT group were significantly greater than those in the HCP+SN and HCP+CIMT groups (P < .05). Motor function were positively correlated with the density of neurons (r = 0.450 and 0.309, respectively; P < .05) and neurofilament (r = 0.717 and 0.567, respectively; P < .05). Conclusions. CIMT might promote the remodeling of neurons, neurofilament, dendrites/axon areas, and myelin in the motor cortex by partially inhibiting the Nogo-A/NgR/RhoA/ROCK pathway, thereby promoting the improvement of motor function in HCP mice.

Magnet-targeted delivery of bone marrow-derived mesenchymal stem cells improves therapeutic efficacy following hypoxic-ischemic brain injury

Stem cell transplantation may represent a feasible therapeutic option for the recovery of neurological function in children with hypoxic-ischemic brain injury; however, the therapeutic efficacy of bone marrow-derived mesenchymal stem cells largely depends on the number of cells that are successfully transferred to the target. Magnet-targeted drug delivery systems can use a specific magnetic field to attract the drug to the target site, increasing the drug concentration. In this study, we found that the double-labeling using superparamagnetic iron oxide nanoparticle and poly-L-lysine (SPIO-PLL) of bone marrow-derived mesenchymal stem cells had no effect on cell survival but decreased cell proliferation 48 hours after labeling. Rat models of hypoxic-ischemic brain injury were established by ligating the left common carotid artery. One day after modeling, intraventricular and caudal vein injections of 1 × 10⁵ SPIO-PLL-labeled bone marrow-derived mesenchymal stem cells were performed. Twenty-four hours after the intraventricular injection, magnets were fixed to the left side of the rats’ heads for 2 hours. Intravoxel incoherent motion magnetic resonance imaging revealed that the perfusion fraction and the diffusion coefficient of rat brain tissue were significantly increased in rats treated with SPIO-PLL-labeled cells through intraventricular injection combined with magnetic guidance, compared with those treated with SPIO-PLL-labeled cells through intraventricular or tail vein injections without magnetic guidance. Hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining revealed that in rats treated with SPIO-PLL-labeled cells through intraventricular injection under magnetic guidance, cerebral edema was alleviated, and apoptosis was decreased. These findings suggest that targeted magnetic guidance can be used to improve the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for hypoxic-ischemic brain injury. This study was approved by the Animal Care and Use Committee of The Second Hospital of Dalian Medical University, China (approval No. 2016-060) on March 2, 2016.

Electroacupuncture on the Scalp over the Motor Cortex Ameliorates Behavioral Deficits Following Neonatal Hypoxia-Ischemia in Rats via the Activation of Neural Stem Cells

Electroacupuncture (EA) therapy via alternating current stimulation on the scalp over the motor cortex is used for the treatment of brain disorders. Perinatal hypoxia-ischemia (HI), a brain injury in newborns, leads to long-term neurologic complications. Here, we investigated whether EA could promote functional improvements and neurogenesis in a neonatal HI rat model. A neonatal HI rat model was induced by permanent ligation of the left carotid artery in postnatal day 7 pups. EA for neonatal HI rats was performed at 2 Hz (1, 3, or 5 mA; 20 min) from 4–6 weeks after birth. HI rats undergoing EA had improved motor and memory function, with the greatest improvement after 3 mA EA. The corpus callosum was significantly thicker and showed a significant increase in proliferating astrocytes in the 3 mA EA group. We observed proliferating cells and a greater number of newly developed neurons and astrocytes in the subventricular zone and dentate gyrus of the 3 mA EA group than in those of the HI group. These results suggest that EA promotes functional improvements following neonatal HI assault via the proliferation and differentiation of neural stem cells. This effect was the strongest after 3 mA EA, suggesting that this is the optimal treatment dose.

Hypoxic-Ischemic Encephalopathy and Mitochondrial Dysfunction: Facts, Unknowns, and Challenges

Significance: Hypoxic-ischemic events due to intrapartum complications represent the second cause of neonatal mortality and initiate an acute brain disorder known as hypoxic-ischemic encephalopathy (HIE). In HIE, the brain undergoes primary and secondary energy failure phases separated by a latent phase in which partial neuronal recovery is observed. A hypoxic-ischemic event leads to oxygen restriction causing ATP depletion, neuronal oxidative stress, and cell death. Mitochondrial dysfunction and enhanced oxidant formation in brain cells are characteristic phenomena associated with energy failure. Recent Advances: Mitochondrial sources of oxidants in neurons include complex I of the mitochondrial respiratory chain, as a key contributor to O₂^•- production via succinate by a reverse electron transport mechanism. The reaction of O₂^•- with nitric oxide (^•NO) yields peroxynitrite, a mitochondrial and cellular toxin. Quantitation of the redox state of cytochrome c oxidase, through broadband near-infrared spectroscopy, represents a promising monitoring approach to evaluate mitochondrial dysfunction in vivo in humans, in conjunction with the determination of cerebral oxygenation and their correlation with the severity of brain injury. Critical Issues: The energetic failure being a key phenomenon in HIE connected with the severity of the encephalopathy, measurement of mitochondrial dysfunction in vivo provides an approach to assess evolution, prognosis, and adequate therapies. Restoration of mitochondrial redox homeostasis constitutes a key therapeutic goal. Future Directions: While hypothermia is the only currently accepted therapy in clinical management to preserve mitochondrial function, other mitochondria-targeted and/or redox-based treatments are likely to synergize to ensure further efficacy.

Usefulness of pathological examinations of the central nervous system for monitoring and controlling perinatal lamb mortality

Correct diagnosis of cause of death is necessary to suggest the most effective management interventions to reduce perinatal lamb mortality. Haemorrhage on the surface of the brain has been used as a field diagnostic tool to allocate lambs to a cause of death category, but the usefulness of this method was unclear. This study aimed to evaluate whether gross pathology was related to neuronal death and whether haemorrhage of the central nervous system (CNS) was distinct between differing causes of death, enabling indicators to be used in field diagnoses. Lambs dying from natural causes (n = 64) and from euthanasia (n = 7) underwent postmortem examination, then the brain and spinal cord were extracted and examined histologically. Histological changes consistent with neuronal death were not detected in any lamb. Haemorrhage of the meninges and/or parenchyma of the CNS occurred in all lambs. The age of the haemorrhage indicated that it occurred near the time of death in most lambs. Dilation of blood vessels varied in severity but appeared to be unrelated to causal diagnosis, severity of subcutaneous oedema, breathing or milk status. Moderate or severe dilation of blood vessels and haemorrhage of the CNS did not occur in all lambs with alternative clear indicators of dystocia and occurred in all death classifications, so it could not be used as diagnostic indicators for classification of cause of death. Dilation and haemorrhage were unrelated to neuronal damage and may have been artefactual. In conclusion, haemorrhage of the CNS was not indicative of neuronal damage and could not be used to distinguish between lambs with clear indicators of differing causes of death, so it is not recommended as a field diagnostic tool.

Oxymatrine protects neonatal rat against hypoxic-ischemic brain damage via PI3K/Akt/GSK3β pathway

AIMS

In this study we aimed to explore the specific effect and mechanism of oxymatrine on neonatal rats hypoxic-ischemic brain damage.

MATERIALS AND METHODS

Hypoxia-ischemia damage model was built by ligaturing the left common carotid artery in 7-day-old rat. Rat pups in OMT group received intraperitoneal injection with oxymatrine (120 mg/kg). Oxygen glucose deprivation/reperfusion model was created in hippocampal neurons. Neurological behavioral, histopathological alteration, cell viability, intracellular Ca²⁺ concentration, MMP and cell apoptosis were used in damage evaluation.

KEY FINDINGS

The results shown that oxymatrine regulated brain damage and cell apoptosis by controlling NR2B-PI3K/Akt/GSK3β signaling pathway.

SIGNIFICANCE

Neonatal hypoxic-ischemic brain damage is a destructive injury that leading to death and detrimental neurological deficits. Oxymatrine is a natural alkaloid compound that can alleviate the ischemic cerebral infarction. In the study, 120 mg/kg oxymatrine decreased neuroethology damage and neuronal damage in the cerebral cortex and the hippocampus CA3. Moreover, 0.2, 1, 5 μg/ml oxymatrine improved cell survival, decreased cell apoptosis. The utilization of LY293004 (PI3K signaling pathway inhibitor) also supported that oxymatrine ameliorated neonatal hypoxic-ischemic brain damage and cell injury by controlling NR2B-PI3K/Akt/GSK3β signaling pathway.

The Effect of Environmental Enrichment on Glutathione-Mediated Xenobiotic Metabolism and Antioxidation in Normal Adult Mice

Olfactory bulb (OB) plays an important role in protecting against harmful substances via the secretion of antioxidant and detoxifying enzymes. Environmental enrichment (EE) is a common rehabilitation method and known to have beneficial effects in the central nervous system. However, the effects of EE in the OB still remain unclear. At 6 weeks of age, CD-1® (ICR) mice were assigned to standard cages or EE cages. After 2 months, we performed proteomic analysis. Forty-four up-regulated proteins were identified in EE mice compared to the control mice. Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes Pathway demonstrated that the upregulated proteins were mainly involved in metabolic pathways against xenobiotics. Among those upregulated proteins, 9 proteins, which participate in phase I or II of the xenobiotic metabolizing process and are known to be responsible for ROS detoxification, were validated by qRT-PCR. To explore the effect of ROS detoxification mediated by EE, glutathione activity was measured by an ELISA assay. The ratio of reduced glutathione to oxidized glutathione was significantly increased in EE mice. Based on a linear regression analysis, GSTM2 and UGT2A1 were found to be the most influential genes in ROS detoxification. For further analysis of neuroprotection, the level of iNOS and the ratio of Bax to Bcl-2 were significantly decreased in EE mice. While TUNEL⁺ cells were significantly decreased, Ki67⁺ cells were significantly increased in EE mice, implicating that EE creates an optimal state for xenobiotic metabolism and antioxidant activity. Taken together, our results suggested that EE protects olfactory layers via the upregulation of glutathione-related antioxidant and xenobiotic metabolizing enzymes, eventually lowering ROS-mediated inflammation and apoptosis and increasing neurogenesis. This study may provide an opportunity for a better understanding of the beneficial effects of EE in the OB.

Tert-butylhydroquinone post-treatment attenuates neonatal hypoxic-ischemic brain damage in rats

Hypoxic-ischemic (HI) encephalopathy is a leading cause of dire mortality and morbidity in neonates. Unfortunately, no effective therapies have been developed as of yet. Oxidative stress plays a critical role in pathogenesis and progression of neonatal HI. Previously, as a Nrf2 activator, tert-butylhydroquinone (TBHQ) has been demonstrated to exert neuroprotection on brain trauma and ischemic stroke models, as well as oxidative stress-induced cytotoxicity in neurons. It is, however, still unknown whether TBHQ administration can protect against oxidative stress in neonatal HI brain injury. This study was undertaken to determine the neuroprotective effects and mechanisms of TBHQ post-treatment on neonatal HI brain damage. Using a neonatal HI rat model, we demonstrated that TBHQ markedly abated oxidative stress compared to the HI group, as evidenced by decreased oxidative stress indexes, enhanced Nrf2 nuclear accumulation and DNA binding activity, and up-regulated expression of Nrf2 downstream antioxidative genes. Administration of TBHQ likewise significantly suppressed reactive gliosis and release of inflammatory cytokines, and inhibited apoptosis and neuronal degeneration in the neonatal rat cerebral cortex. In addition, infarct size and neuronal damage were attenuated distinctly. These beneficial effects were accompanied by improved neurological reflex and motor coordination as well as amelioration of spatial learning and memory deficits. Overall, our results provide the first documentation of the beneficial effects of TBHQ in neonatal HI model, in part conferred by activation of Nrf2 mediated antioxidative signaling pathways.

Combined therapy involving electroacupuncture and treadmill exercise attenuates demyelination in the corpus callosum by stimulating oligodendrogenesis in a rat model of neonatal hypoxia-ischemia

We investigated whether electroacupuncture (EA) and treadmill (TM) exercise improve behaviors related to motor and memory dysfunction in a cerebral palsy-like rat model via activation of oligodendrogenesis. A neonatal hypoxia-ischemia model was created using Sprague-Dawley rats (P7), and these underwent EA stimulation and treadmill training from 3 to 5weeks after hypoxia-ischemia induction. EA treatment was delivered via electrical stimulation (2Hz, 1mA) at two acupoints, Baihui (GV20) and Zusanli (ST36). Behavioral tests showed that EA alleviated motor dysfunction caused by hypoxia-ischemia on a rotarod test, and TM exercise alleviated motor and memory dysfunction seen on cylinder and passive avoidance tests. Combined therapy with EA and TM exercise showed synergistic effects on the cylinder, rotarod, and catwalk tests. TM exercise significantly restored corpus callosum thickness, and combined therapy with EA and TM restored myelin basic protein (MBP) levels in this region. While EA stimulation only increased activation of cAMP-response element binging protein (CREB) in oligodendrocytes of the corpus callosum, TM exercise increased newly generated oligodendrocyte progenitor cells or oligodendrocytes via activation of CREB. Synergistic effects on oligodendrogenesis were also observed by the combined therapy. Furthermore, the combined therapy induced mature brain-derived neurotrophic factor (BDNF) expression in the cerebral cortex. These results demonstrate that combined therapy with EA and TM exercise may restore myelin components following neonatal hypoxia-ischemia via upregulation of oligodendrogenesis involving CREB/BDNF signaling, which subsequently improves motor and memory function. Therefore, combined therapy with EA and TM exercise offers another treatment option for functional recovery from injuries caused by neonatal hypoxia-ischemia, such as cerebral palsy.

Neurobehavioral Assessments in a Mouse Model of Neonatal Hypoxic-ischemic Brain Injury

We performed unilateral carotid artery occlusion on CD-1 mice to create a neonatal hypoxic-ischemic (HI) model and investigated the effects of neonatal HI brain injury by studying neurobehavioral functions in these mice compared to non-operated (i.e., normal) mice. During the study, Rice-Vannucci's method was used to induce neonatal HI brain damage in postnatal day 7-10 (P7-10) mice. The HI operation was performed on the pups by unilateral carotid artery ligation and exposure to hypoxia (8% O2 and 92% N2 for 90 min). One week after the operation, the damaged brains were evaluated with the naked eye through the semi-transparent skull and were categorized into subgroups based on the absence ("no cortical injury" group) or presence ("cortical injury" group) of cortical injury, such as a lesion in the right hemisphere. On week 6, the following neurobehavioral tests were performed to evaluate the cognitive and motor functions: passive avoidance task (PAT), ladder walking test, and grip strength test. These behavioral tests are helpful in determining the effects of neonatal HI brain injury and are used in other mouse models of neurodegenerative diseases. In this study, neonatal HI brain injury mice showed motor deficits that corresponded to right hemisphere damage. The behavioral test results are relevant to the deficits observed in human neonatal HI patients, such as cerebral palsy or neonatal stroke patients. In this study, a mouse model of neonatal HI brain injury was established and showed different degrees of motor deficits and cognitive impairment compared to non-operated mice. This work provides basic information on the HI mouse model. MRI images demonstrate the different phenotypes, separated according to the severity of brain damage by motor and cognitive tests.

Comparative analysis of the beneficial effects of treadmill training and electroacupuncture in a rat model of neonatal hypoxia-ischemia

In the present study, we investigated whether treadmill training and electroacupuncture (EA) have autonomous or synergistic beneficial effects on deficits caused by neonatal hypoxia-ischemia in Sprague-Dawley rats. For this purpose, rats subjected to hypoxia-ischemia underwent treadmill training and EA stimulation from 4 to 8 weeks of age. Conventional EA (CEA) and scalp EA (SEA) were delivered by electrical stimulation (2 Hz, 1 mA) at traditional acupoints and at the scalp to the primary motor area, respectively. In the behavioral examination, markedly improved performances in the rotarod test were observed in the rats that underwent treadmill exercise, and in the rats that underwent treadmill exercise and CEA compared to the untreated rats subjected to hypoxia-ischemia. An improvement was also observed in the passive avoidance test in the rats that underwent treadmill training and EA. As shown by western blot analysis, the expression levels of neuronal nuclei (NeuN), 2′,3′-cyclic-nucleotide 3′-phosphodiesterase and myelin basic protein (MBP) exhibited a significant decrease in the contralateral subventricular zone (SVZ) of the rats subjected to hypoxia-ischemia compared to the controls; however, these expression levels increased following treadmill exercise and EA stimulation. As shown by immunohistochemical analyses, the thickness of the corpus callosum and the integrated optical density (IOD) of MBP were significantly increased in the rats subjected to treadmill exercise and EA compared to the untreated rats subjected to hypoxiaa-ischemia. The synergistic effects of treadmill training and EA were also observed in the protein levels and IOD of MBP. A marked increase in the number of bromodeoxyuridine (BrdU)- and BrdU/NeuN-positive cells in the contralateral SVZ was also observed in the rats that underwent treadmill training and EA; the number of BrdU-positive cells was synergistically affected by treadmill training and EA. These results suggest that treadmill training and EA stimulation contribute to the enhancement of behavioral recovery following hypoxia-ischemia via the upregulation of myelin components and neurogenesis. Thus, treatment with EA stimulation, as well as treadmill training offers another treatment option to promote functional recovery in cerebral palsy.

Histological and functional assessment of the efficacy of constraint-induced movement therapy in rats following neonatal hypoxic-ischemic brain injury

Constraint-induced movement therapy (CIMT) is used in stroke rehabilitation to promote recovery of upper limb motor function. However, its efficacy in improving functional outcomes in children with hemiplegic cerebral palsy has not been clearly determined in clinical or experimental research. The aim of our study was to assess the efficacy of a new experimental model of CIMT, evaluated in terms of mortality, stress, motor and cognitive function in rats having undergone a neonatal hypoxic-ischemic (HI) brain injury. Neonatal HI injury was induced at post-natal day 7 through unilateral ligation of the common carotid artery followed by exposure to hypoxia for 2 h. CIMT was implemented at 3 weeks, post-HI injury, using a pouch to constrain the unimpaired forelimb and forcing use of the affected forelimb using a motorized treadmill. After HI injury, animals demonstrated motor and cognitive deficits, as well as volumetric decreases in the ipsilateral hemisphere to arterial occlusion. CIMT yielded a modest recovery of motor and cognitive function, with no effect in reducing the size of the HI lesion or post-HI volumetric decreases in brain tissue. Therefore, although animal models of stroke have identified benefits of CIMT, CIMT was not sufficient to enhance brain tissue development and functional outcomes in an animal model of hemiplegic cerebral palsy. Based on our outcomes, we suggest that CIMT can be used as an adjunct treatment to further enhance the efficacy of a program of rehabilitation in children with hemiplegic cerebral palsy.

Beneficial effects of Jiawei Shenqi-wan and treadmill training on deficits associated with neonatal hypoxic-ischemia in rats

Jiawei Shenqi-wan (JSQW), which comprises Shenqi-wan and two additional medicinal herbs, has been widely used for the treatment of various growth impairments, including cerebral palsy. In the present study, JSQW was administered to hypoxic-ischemic Sprague-Dawley rats that underwent treadmill training from 4-7 weeks of age to examine the beneficial effects of combined JSQW and treadmill therapy. Behavioral examinations were performed and a significant improvement in cylinder test performance was observed in rats treated with treadmill training compared with hypoxic-ischemia rats (P<0.05), as well as a significant improvement in passive avoidance test performance for rats treated with JSQW (P<0.05). The thickness of the corpus callosum and the integrated optical density (IOD) of myelin basic protein (MBP) were significantly increased by treatment with treadmill therapy alone (P<0.01 and P<0.001, respectively) and treatment with both JSQW and treadmill significantly increased the IOD of MBP compared with hypoxic-ischemia rats (P<0.001). Western blot analysis revealed that the expression of neuronal nuclei (NeuN) and doublecortin (Dcx) significantly decreased (P<0.001 and P<0.05, respectively) and MBP expression markedly decreased in the ipsilateral subventricular zone of hypoxic-ischemic rats compared with the control group; however, the expression of NeuN was significantly recovered by treatment with both JSQW and treadmill training (P<0.05). Furthermore, Dcx expression was significantly recovered by treatment with JSQW (P<0.05), and MBP expression was significantly restored by treatment with treadmill training (P<0.01). In the immunohistochemical analyses, a significant increase in the number of bromodeoxyuridine (BrdU) positive cells in this region was observed in treadmill-treated rats (P<0.05), whereas significant increases in the number of Brdu/Dcx or NeuN or glial fibrillary acidic protein double-positive cells were observed only in the group co-treated with JSQW and treadmill (P<0.01, P<0.05 and P<0.001, respectively). These results suggest that JSQW and treadmill training may contribute to behavior recovery following hypoxic-ischemia, and JSQW treatment was particularly effective in promoting memory function via enhancing the differentiation of neuronal progenitor cells. The results of the present study therefore suggest that JSQW may provide an additional treatment option for functional recovery with treadmill training in cerebral palsy.

In Vivo Expression of Reprogramming Factors Increases Hippocampal Neurogenesis and Synaptic Plasticity in Chronic Hypoxic-Ischemic Brain Injury

Neurogenesis and synaptic plasticity can be stimulated in vivo in the brain. In this study, we hypothesized that in vivo expression of reprogramming factors such as Klf4, Sox2, Oct4, and c-Myc would facilitate endogenous neurogenesis and functional recovery. CD-1® mice were induced at 1 week of age by unilaterally carotid artery ligation and exposure to hypoxia. At 6 weeks of age, mice were injected GFP only or both four reprogramming factors and GFP into lateral ventricle. Passive avoidance task and open field test were performed to evaluate neurobehavioral function. Neurogenesis and synaptic activity in the hippocampus were evaluated using immunohistochemistry, qRT-PCR, and/or western blot analyses. Whereas BrdU⁺GFAP⁺ cells in the subgranular zone of the hippocampus were not significantly different, the numbers of BrdU⁺βIII-tubulin⁺ and BrdU⁺NeuN⁺ cells were significantly higher in treatment group than control group. Expressions of synaptophysin and PSD-95 were also higher in treatment group than control group. Importantly, passive avoidance task and open field test showed improvement in long-term memory and decreased anxiety in treatment group. In conclusion, in vivo expression of reprogramming factors improved behavioral functions in chronic hypoxic-ischemic brain injury. The mechanisms underlying these repair processes included endogenous neurogenesis and synaptic plasticity in the hippocampus.

Effects of 3-h hypothermia after neonatal hyperthermic hypoxic-ischemic encephalopathy in rat models on behavioral prognosis and anatomical and histological features after growth

OBJECTIVE

To clarify the effects of 3-h hypothermia on learning ability and motor function after growth, employing neonatal rat models with hyperthermic hypoxic-ischemic encephalopathy (HIE).

METHODS

We divided all rats into three groups: N (adult rats after neonatal hyperthermic HIE without subsequent 3-h hypothermia), H (adult rats after neonatal hyperthermic HIE with subsequent 3-h hypothermia) and Sham (S) groups. We evaluated their malfunctions with the rota-rod test and the step-down passive avoidance test. We also analyzed the cerebrum width and the hippocampal CA1 area of the insulted hemisphere.

RESULTS

In the rota-rod test, the result of the N group was significantly worse than that of the S group. In the step-down passive avoidance test, the result of the N group was significantly worse than those of the S and H groups. The longest cerebrum width and the hippocampal CA1 area of the insulted hemisphere of the N group were significantly smaller than those of the S and H groups.

CONCLUSION

Neonatal hyperthermic hypoxic-ischemic insult restricts motor function and learning ability after growth, and such neuronal malfunctions can be relieved by hypothermia for 3 h soon after neonatal HIE.

Recapitulation of in vivo-like paracrine signals of human mesenchymal stem cells for functional neuronal differentiation of human neural stem cells in a 3D microfluidic system

Paracrine signals produced from stem cells influence tissue regeneration by inducing the differentiation of endogenous stem or progenitor cells. However, many recent studies that have investigated paracrine signaling of stem cells have relied on either two-dimensional transwell systems or conditioned medium culture, neither of which provide optimal culture microenvironments for elucidating the effects of paracrine signals in vivo. In this study, we recapitulated in vivo-like paracrine signaling of human mesenchymal stem cells (hMSCs) to enhance functional neuronal differentiation of human neural stem cells (hNSCs) in three-dimensional (3D) extracellular matrices (ECMs) within a microfluidic array platform. In order to amplify paracrine signaling, hMSCs were genetically engineered using cationic polymer nanoparticles to overexpress glial cell-derived neurotrophic factor (GDNF). hNSCs were cultured in 3D ECM hydrogel used to fill central channels of the microfluidic device, while GDNF-overexpressing hMSCs (GDNF-hMSCs) were cultured in channels located on both sides of the central channel. This setup allowed for mimicking of paracrine signaling between genetically engineered hMSCs and endogenous hNSCs in the brain. Co-culture of hNSCs with GDNF-hMSCs in the 3D microfluidic system yielded reduced glial differentiation of hNSCs while significantly enhancing differentiation into neuronal cells including dopaminergic neurons. Neuronal cells produced from hNSCs differentiating in the presence of GDNF-hMSCs exhibited functional neuron-like electrophysiological features. The enhanced paracrine ability of GDNF-hMSCs was finally confirmed using an animal model of hypoxic-ischemic brain injury. This study demonstrates the presented 3D microfluidic array device can provide an efficient co-culture platform and provide an environment for paracrine signals from transplanted stem cells to control endogenous neuronal behaviors in vivo.

Broccoli sprout supplementation during pregnancy prevents brain injury in the newborn rat following placental insufficiency

Chronic placental insufficiency and subsequent intrauterine growth restriction (IUGR) increase the risk of hypoxic-ischemic encephalopathy in the newborn by 40 fold. The latter, in turn, increases the risk of cerebral palsy and developmental disabilities. This study seeks to determine the effectiveness of broccoli sprouts (BrSp), a rich source of the isothiocyanate sulforaphane, as a neuroprotectant in a rat model of chronic placental insufficiency and IUGR. Placental insufficiency and IUGR was induced by bilateral uterine artery ligation (BUAL) on day E20 of gestation. Dams were fed standard chow or chow supplemented with 200mg of dried BrSp from E15 - postnatal day 14 (PD14). Controls received Sham surgery and the same dietary regime. Pups underwent neurologic reflex testing and open field testing, following which they were euthanized and their brains frozen for neuropathologic assessment. Compared to Sham, IUGR pups were delayed in attaining early reflexes and performed worse in the open field, both of which were significantly improved by maternal supplementation of BrSp (p<0.05). Neuropathology revealed diminished white matter, ventricular dilation, astrogliosis and reduction in hippocampal neurons in IUGR animals compared to Sham, whereas broccoli sprout supplementation improved outcome in all histological assessments (p<0.05). Maternal dietary supplementation with BrSp prevented the detrimental neurocognitive and neuropathologic effects of chronic intrauterine ischemia. These findings suggest a novel approach for prevention of cerebral palsy and/or developmental disabilities associated with placental insufficiency.

Neurological outcomes of animal models of uterine artery ligation and relevance to human intrauterine growth restriction: a systematic review

AIM

This review explores the molecular, neurological, and behavioural outcomes in animal models of uterine artery ligation. We analyse the relevance of this type of model to the pathological and functional phenotypes that are consistent with cerebral palsy and its developmental comorbidities in humans.

METHOD

A literature search of the PubMed database was conducted for research using the uterine artery ligation model published between 1990 and 2013. From the studies included, any relevant neuroanatomical and behavioural deficits were then summarized from each document and used for further analysis.

RESULTS

There were 25 papers that met the criteria included for review, and several outcomes were summarized from the results of these papers. Fetuses with growth restriction demonstrated a gradient of reduced body weight with a relative sparing of brain mass. There was a significant reduction in the size of the somatosensory cortex, hippocampus, and corpus callosum. The motor cortex appeared to be spared of identifiable deficits. Apoptotic proteins were upregulated, while those important to neuronal survival, growth, and differentiation were downregulated. Neuronal apoptosis and astrogliosis occurred diffusely throughout the brain regions. White matter injury involved oligodendrocyte precursor maturation arrest, hypomyelination, and an aberrant organization of existing myelin. Animals with growth restriction demonstrated deficits in gait, memory, object recognition, and spatial processing.

INTERPRETATION

This review concludes that neuronal death, white matter injury, motor abnormalities, and cognitive deficits are important outcomes of uterine artery ligation in animal models. Therefore, this is a clinically relevant type of model, as these findings resemble deficits in human cerebral palsy.

Protective effect of polydatin on learning and memory impairments in neonatal rats with hypoxic‑ischemic brain injury by up‑regulating brain‑derived neurotrophic factor

Polydatin is a key component of Polygonum cuspidatum, a herb with medical and nutritional value. The present study investigated the protective effect of polydatin against learning and memory impairment in neonatal rats with hypoxic‑ischemic brain injury (HIBI). The unilateral common carotid artery ligation method was used to generate neonatal HIBI rats. Y‑maze testing revealed that rats with HIBI exhibited memory impairment, while rats with HIBI treated with polydatin displayed enhanced long‑term learning and memory. Of note, polydatin was found to upregulate the expression of hippocampal brain‑derived neurotrophic factor (BDNF) in rats with HIBI. BDNF has a role in protecting HIBI‑induced brain tissue injury and alleviating memory impairment. These findings showed that polydatin had a protective effect against learning and memory impairment in neonatal rats with HIBI and that the protective effect may be mediated through the upregulation of BDNF.

Role of immunoglobulin in neuronal apoptosis in a neonatal rat model of hypoxic ischemic brain injury

The objective of the present study was to evaluate the neuroprotective effects of immunoglobulin (Ig) in a neonatal hypoxic ischemic (HI) rat model. Seven-day-old rat pups were randomly assigned to control, hypoxia and hypoxia + Ig groups. The rats in the hypoxia +Ig group were intraperitoneally administered 1 g/kg Ig once, immediately after hypoxia. Saline was administered to the rats in the hypoxia group at the same time point. Eight rats from each of the Ig + hypoxia and hypoxia groups were sacrificed by decapitation 4 and 24 h following the administration of Ig or saline. The rats of the control group were sacrificed at the 4 h time-point. Caspase-3 activity, as well as IL-1β, IL-6 and TNF-α mRNA expression levels, were studied in the left ischemic hemispheres. Induction of cerebral ischemia increased the TNF-α, IL-6 and IL-1β mRNA expression levels significantly at 4 and 24 h in the left ischemic hemispheres in the hypoxia group compared with those in the control group. The systemic administration of Ig following HI encephalopathy significantly reduced the TNF-α, IL-6 and IL-1β mRNA expression levels in the ischemic tissue in the Ig + hypoxia group compared with those in the hypoxia group. In the hypoxia group, caspase-3 activity in the left half of the brain was found to be significantly increased compared with that in the control group. Caspase-3 activity in the Ig + hypoxia group was significantly lower than that in the hypoxia group. The observations of the present study indicate that Ig administration may be an efficient treatment approach for reducing cerebral apoptosis associated with hypoxic ischemia.

The effects of intraperitoneal pentoxifylline treatment in rat pups with hypoxic-ischemic encephalopathy

BACKGROUND

The aim of this study was to evaluate the effects of postischemic treatment with pentoxifylline on the cytokine gene expressions and neuronal apoptosis in neonatal rat model of hypoxic-ischemic encephalopathy.

METHODS

Seven-day-old Wistar rat pups (n = 40) of either sex, delivered spontaneously, were used in this experimental study. Control group (n = 8): after median neck incision was made, neither ligation nor hypoxia was performed, ischemia group (n = 16): 0.5 mL of saline was injected intraperitoneally immediately after hypoxia. Pentoxifylline and ischemia groups (n = 16): the rat pups were administered intraperitoneally 60 mg/kg of pentoxifylline immediately after hypoxia. Eight rats from ischemia and pentoxifylline + ischemia groups were sacrificed 4 and 24 hours after drug administration. Control group mice were decapitated 4 hours after hypoxia. Caspase-3 activity, interleukin-1β, and tumor necrosis factor-α messenger RNA expression levels were studied in the left half of the brain.

RESULTS

Induction of cerebral ischemia increased tumor necrosis factor-α and interleukin-1β messenger RNA expression levels significantly at 4 hours and 24 hours following ischemia in the left ischemic hemispheres in the ischemia group as compared with the control group. Systemic administration of pentoxifylline immediately after hypoxic-ischemic encephalopathy significantly reduced the tumor necrosis factor-α and interleukin-1β messenger RNA expression levels in ischemic tissue as compared with the ischemia group. Caspase-3 activities in the left half of the brains of ischemia group were found to be increased significantly as compared with control group. Caspase-3 activities in the brains of pentoxifylline + ischemia groups were significantly lower than in that of ischemia group.

CONCLUSIONS

Based on the significantly lower interleukin-1β and tumor necrosis factor-α gene expression measured after 4 and 24 hours and significantly reduced caspase-3 activity measured colorimetrically in the animals treated with pentoxifylline, our findings suggest that pentoxifylline may reduce brain damage due to hypoxic-ischemic injury.

Fibroblast growth factor-2 induced by enriched environment enhances angiogenesis and motor function in chronic hypoxic-ischemic brain injury

This study aimed to investigate the effects of enriched environment (EE) on promoting angiogenesis and neurobehavioral function in an animal model of chronic hypoxic-ischemic (HI) brain injury. HI brain damage was induced in seven day-old CD-1® mice by unilateral carotid artery ligation and exposure to hypoxia (8% O2 for 90 min). At six weeks of age, the mice were randomly assigned to either EE or standard cages (SC) for two months. Rotarod, forelimb-use asymmetry, and grip strength tests were performed to evaluate neurobehavioral function. In order to identify angiogenic growth factors regulated by EE, an array-based multiplex ELISA assay was used to measure the expression in frontal cortex, striatum, and cerebellum. Among the growth factors, the expression of fibroblast growth factor-2 (FGF-2) was confirmed using western blotting. Platelet endothelial cell adhesion molecule-1 (PECAM-1) and α-smooth muscle actin (α-SMA) were also evaluated using immunohistochemistry. As a result, mice exposed to EE showed significant improvements in rotarod and ladder walking performances compared to SC controls. The level of FGF-2 was significantly higher in the frontal cortex of EE mice at 8 weeks after treatment in multiplex ELISA and western blot. On the other hand, FGF-2 in the striatum significantly increased at 2 weeks after exposure to EE earlier than in the frontal cortex. Expression of activin A was similarly upregulated as FGF-2 expression pattern. Particularly, all animals treated with FGF-2 neutralizing antibody abolished the beneficial effect of EE on motor performance relative to mice not given anti-FGF-2. Immunohistochemistry showed that densities of α-SMA⁺ and PECAM-1⁺ cells in frontal cortex, striatum, and hippocampus were significantly increased following EE, suggesting the histological findings exhibit a similar pattern to the upregulation of FGF-2 in the brain. In conclusion, EE enhances endogenous angiogenesis and neurobehavioral functions mediated by upregulation of FGF-2 in chronic hypoxic-ischemic brain injury.

Environmental Enrichment Synergistically Improves Functional Recovery by Transplanted Adipose Stem Cells in Chronic Hypoxic-Ischemic Brain Injury

We investigated the effects of environmental enrichment (EE) on the function of transplanted adipose stem cells (ASCs) and the combined effect of EE and ASC transplantation on neurobehavioral function in an animal model of chronic hypoxic-ischemic (HI) brain injury. HI brain damage was induced in 7-day-old mice by unilateral carotid artery ligation and exposure to hypoxia (8% O2 for 90 min). At 6 weeks of age, the mice were randomly injected with either ASCs or PBS into the striatum and were randomly assigned to either EE or standard cages (SC), comprising ASC-EE ( n = 18), ASC-SC ( n = 19), PBS-EE ( n = 12), PBS-SC ( n = 17), and untreated controls ( n = 23). Rotarod, forelimb-use asymmetry, and grip strength tests were performed to evaluate neurobehavioral function. The fate of transplanted cells and the levels of endogenous neurogenesis, astrocyte activation, and paracrine factors were also measured. As a result, EE and ASC transplantation synergistically improved rotarod latency, forelimb-use asymmetry, and grip strength compared to those of the other groups. The number of engrafted ASCs and βIII-tubulin+ neurons derived from the transplanted ASCs was significantly higher in mice in EE than those in SC. EE and ASC transplantation also synergistically increased BrdU+βIII-tubulin+ neurons, GFAP+ astrocytic density, and fibroblast growth factor 2 (FGF2) level but not the level of CS-56+ glial scarring in the striatum. In conclusion, EE and ASC transplantation synergistically improved neurobehavioral functions. The underlying mechanisms of this synergism included enhanced repair processes such as higher engraftment of the transplanted ASCs, increased endogenous neurogenesis and astrocytic activation coupled with upregulation of FGF2.

Cerebral blood volume combined with amplitude-integrated EEG can be a suitable guide to control hypoxic/ischemic insult in a piglet model

INTRODUCTION

The purposes of this study are to compare two hypoxic/ischemic (H/I) insults using amplitude-integrated EEG (aEEG), alone or combined with cerebral blood volume (CBV), as a guide to control hypoxia and to determine which protocol most effectively produces a consistent degree of survivable neuropathological damage in a newborn piglet model of perinatal asphyxia.

METHODS

Eighteen piglets were subjected to H/I insult of 20-min low aEEG (LAEEG). After the 20-min, the aEEG group was maintained with low mean arterial blood pressure for 10min. The procedure for the aEEG plus CBV group was stopped if CBV became the rated value after 20min of LAEEG. We measured changes in CBV using a near-infrared time-resolved spectroscopy (TRS) and cerebral electrocortical activity using aEEG until 6h post-insult. At 5days post insult, the piglets' brains were perfusion-fixed and stained with hematoxylin/eosin. Piglets were grouped as undamaged or damaged; piglets that did not survive to 5days were grouped separately as dead.

RESULTS

Among surviving piglets, CBV combined with aEEG resulted in significantly greater percentage of damaged piglets than aEEG alone.

CONCLUSIONS

We conclude that combining CBV with aEEG may be a more effective guide to control H/I insult in a newborn piglet model than aEEG alone.

A case-control study of hypoxic-ischemic encephalopathy in newborn infants at >36 weeks gestation

OBJECTIVE

The purpose of this study was to determine risk factors that are associated with hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

This was a case-control study that included newborn infants with HIE who were admitted to the hospital between January 2001 and December 2008. Two control newborn infants were chosen for each case. Logistic regression and classification and regression tree (CART) analysis that compared control infants and cases with grade 1 HIE and control infants and cases with grades 2 and 3 HIE was performed.

RESULTS

Two hundred thirty-seven cases (newborn infants with grade 1 encephalopathy, 155; newborn infants with grade 2 encephalopathy, 61; newborn infants with grade 3 encephalopathy, 21) and 489 control infants were included. Variables that were associated independently with HIE included higher grade meconium, growth restriction, large head circumference, oligohydramnios, male sex, fetal bradycardia, maternal pyrexia and increased uterine contractility. CART analysis ranked high-grade meconium, oligohydramnios, and the presence of obstetric complications as the most discriminating variables and defined distinct risk groups with HIE rates that ranged from 0-86%.

CONCLUSION

CART analysis provides information to help identify the time at which intervention in labor may be of benefit.

Neuroprotective therapies after perinatal hypoxic-ischemic brain injury

Hypoxic-ischemic (HI) brain injury is one of the main causes of disabilities in term-born infants. It is the result of a deprivation of oxygen and glucose in the neural tissue. As one of the most important causes of brain damage in the newborn period, the neonatal HI event is a devastating condition that can lead to long-term neurological deficits or even death. The pattern of this injury occurs in two phases, the first one is a primary energy failure related to the HI event and the second phase is an energy failure that takes place some hours later. Injuries that occur in response to these events are often manifested as severe cognitive and motor disturbances over time. Due to difficulties regarding the early diagnosis and treatment of HI injury, there is an increasing need to find effective therapies as new opportunities for the reduction of brain damage and its long term effects. Some of these therapies are focused on prevention of the production of reactive oxygen species, anti-inflammatory effects, anti-apoptotic interventions and in a later stage, the stimulation of neurotrophic properties in the neonatal brain which could be targeted to promote neuronal and oligodendrocyte regeneration.

Apoptotic cell death correlates with ROS overproduction and early cytokine expression after hypoxia-ischemia in fetal lambs

Despite advances in neonatology, the hypoxic-ischemic injury in the perinatal period remains the single most important cause of brain injury in the newborn, leading to death or lifelong sequelae. Using a sheep model of intrauterine asphyxia, we evaluated the correlation between reactive oxygen species (ROS) overproduction, cytokine expression, and apoptotic cell death. Fetal lambs were assigned to sham group, nonasphyctic animals; and hypoxia-ischemia (HI) group, lambs subjected to 60 minutes of HI) by partial cord occlusion and sacrificed 3 hours later. Different brain regions were separated to quantify the number of apoptotic cells and the same territories were dissociated for flow cytometry studies. Our results suggest that the overproduction of ROS and the early increase in cytokine production after HI in fetal lambs correlate in a significant manner with the apoptotic index, as well as with each brain region evaluated.

Effects of constraint-induced movement therapy on neurogenesis and functional recovery after early hypoxic-ischemic injury in mice

AIM

Constraint-induced movement therapy (CIMT) has emerged as a promising therapeutic strategy for improving affected upper limb function in children with hemiplegic cerebral palsy (CP). However, little is known about the changes in the brain that are induced by CIMT. This study was designed to investigate these changes and behavioural performance after CIMT intervention in mice with neonatal hypoxic-ischemic brain injury.

METHOD

We utilized the neonatal hypoxic-ischemic brain injury model established in mice pups. Three weeks after the injury, the mice were randomly assigned to the following three groups: the control group (n = 15), the enriched-environment group (n = 17), and the CIMT with an enriched-environment group (CIMT-EE, n = 15). 5-bromo-2-deoxyuridine (BrdU) was injected daily to label proliferating cells during the 2 weeks of intervention.

RESULTS

The CIMT-EE group showed better fall rate in the horizontal ladder rung walking test (mean 5.4%, SD 3.6%) than either the control (mean 14.3%, SD 7.3%; p = 0.001) or enriched-environment (mean 12.4%, SD 7.7%; p = 0.010) groups 2 weeks after the end of intervention. The CIMT-EE group also showed more neurogenesis (mean 7069 cells/mm³, SD 4017 cells/mm³) than either the control group (mean 1555 cells/mm³, SD 1422 cells/mm³; p < 0.001) or enriched-environment group (mean 2994 cells/mm³, SD 3498 cells/mm³; p = 0.001) in the subventricular zone. In the striatum, neurogenesis in the CIMT-EE group (mean 534 cells/mm³, SD 441 cells/mm³) was greater than in the control group (mean 95 cells/mm³, SD 133 cells/mm³; p = 0.001).

INTERPRETATION

There was CIMT-EE enhanced neurogenesis in the brain along with functional benefits in mice after early hypoxic-ischemic brain injury. This is the first study to demonstrate the effects of CIMT on neurogenesis and functional recovery after experimental injury to an immature brain.

Induction of striatal neurogenesis enhances functional recovery in an adult animal model of neonatal hypoxic-ischemic brain injury

While intraventricular administration of epidermal growth factor (EGF) expands the proliferation of neural stem/progenitor cells in the subventricular zone (SVZ), overexpression of brain-derived neurotrophic factor (BDNF) is particularly effective in enhancing striatal neurogenesis. We assessed the induction of striatal neurogenesis and consequent functional recovery after chronic infusion of BDNF and EGF in an adult animal model of neonatal hypoxic-ischemic (HI) brain injury. Permanent brain damage was induced in CD-1 (ICR) mice (P7) by applying the ligation of unilateral carotid artery and hypoxic condition. At 6 weeks of age, the mice were randomly assigned to groups receiving a continuous 2-week infusion of one of the following treatments into the ventricle: BDNF, EGF, BDNF/EGF, or phosphate buffered saline (PBS). Two weeks after treatment, immunohistochemical analysis revealed an increase in the number of BrdU(+) cells in the SVZ and striata of BDNF/EGF-treated mice. The number of new neurons co-stained with BrdU and betaIII-tubulin was also significantly increased in the neostriata of BDNF/EGF-treated mice, compared with PBS group. In addition, the newly generated cells were expressed as migrating neuroblasts labeled with PSA-NCAM or doublecortin in the SVZ and the ventricular side of neostriata. The new striatal neurons were also differentiated as mature neurons co-labeled with BrdU(+)/NeuN(+). When evaluated post-surgical 8 weeks, BDNF/EGF-treated mice exhibited significantly longer rotarod latencies at constant speed (48 rpm) and under accelerating condition (4-80 rpm), relative to PBS and untreated controls. In the forelimb-use asymmetry test, BDNF/EGF-treated mice showed significant improvement in the use of the contralateral forelimb. In contrast, this BDNF/EGF-associated functional recovery was abolished in mice receiving a co-infusion of 2% cytosine-b-d-arabinofuranoside (Ara-C), a mitotic inhibitor. Induction of striatal neurogenesis by the intraventricular administration of BDNF and EGF promoted functional recovery in an adult animal model of neonatal HI brain injury. The effect of Ara-C to completely block functional recovery indicates that the effect may be the result of newly generated neurons. Therefore, this treatment may offer a promising strategy for the restoration of motor function for adults with cerebral palsy (CP).

Hypothermia for hypoxic ischemic encephalopathy in infants > or =36 weeks

Hypoxic ischemic encephalopathy is a serious condition affecting infants which can result in death and disability. This is a summary of pathogenesis of HIE, animal studies of cooling for hypoxic and ischemic models, human hypothermia trials, and the American Academy of Pediatrics publication on hypothermia for HIE. Hypothermia for neonatal HIE is continuing to evolve as a therapy. Studies, gaps in knowledge and opportunities for research are presented herein.

Developmental motor deficits induced by combined fetal exposure to lipopolysaccharide and early neonatal hypoxia/ischemia: a novel animal model for cerebral palsy in very premature infants

A critical issue in animal models of perinatal brain injury is to adapt the pertinent pathophysiological scenarios to their corresponding developmental window in order to induce neuropathological and behavioral characteristics reminiscent to perinatal cerebral palsy (CP). A major problem in most of these animal models designed up to now is that they do not present motor deficits characteristic of CP. Using a unique rat paradigm of prenatal inflammation combined to an early postnatal hypoxia-ischemia pertinent to the context of very early premature human newborns, we were interested in finding out if such experimental conditions might reproduce both histological damages and behavioral deficits previously described in the human context. We showed that exposure to lipopolysaccharide (LPS) or hypoxia-ischemia (H/I) induced behavioral alterations in animals subjected to forced motor activity. When both LPS and H/I aggressions were combined, the motor deficits reached their highest intensity and affected both spontaneous and forced motor activities. LPS+H/I-exposed animals also showed extensive bilateral cortical and subcortical lesions of the motor networks affecting the frontal cortices and underlying white matters fascicles, lenticular nuclei and the substantia nigra. These neuropathological lesions and their associated motor behavioral deficits are reminiscent of those observed in very preterm human neonates affected by subsequent CP and validate the value of the present animal model to test new therapeutic strategies which might open horizons for perinatal neuroprotection.

New concepts in perinatal hypoxia ischemia encephalopathy

This article summarizes recent insights into perinatal hypoxic-ischemic brain injury in the neonate. Before effective treatments can be offered, diagnosis, timing, and an understanding of the pathogenesis are imperative. The analysis of appropriate animal models is also summarized in this review. These models have provided interesting evidence that after hypoxia ischemia, progenitor cells in the postnatal brain are stimulated to generate new neurons and oligodendrocytes. The role of these newly generated cells is unclear, and mechanisms of migration and survival are currently being elucidated. A discussion of more recent imaging techniques, such as diffusion tensor imaging, is provided. This allows for improved understanding of the microstructural organization of white matter and how this is altered by hypoxic-ischemic injury. Neuroprotection with hypothermia is now occurring in full-term neonates that meet clinical criteria; however, specific therapies such as inhibition of non-N-methyl-D-aspartate receptors may offer improved outcomes by targeting specific pathways and populations of cells.

Magnetic resonance imaging in cerebral ischemia: focus on neonates

Magnetic resonance imaging (MRI) has dramatically changed our ability to diagnose and treat stroke as well as follow its evolution and response to treatment. Early stroke and ischemia can be visualized using diffusion-weighted imaging (DWI), which utilizes proton diffusion within tissues as a reporter for evolving neuropathology that reflects cytotoxic edema, particularly during the first several days after injury. Historically, T2-weighted imaging (T2WI) has been used for evaluation of vasogenic edema and also is a reliable indicator of injured tissue late after injury. While visual analysis of MR data can provide information about the evolution of injury, quantitative analyses allow definitive and objective evaluations of injury size and location and the effectiveness of novel therapeutic strategies. We review the clinical basis of imaging for stroke and ischemia diagnosis and the methods for post-processing of MR data that could provide novel insights into the evolution and pathophysiology of stroke in the newborn.

Danqi Piantan Jiaonang does not modify hemostasis, hematology, and biochemistry in normal subjects and stroke patients

BACKGROUND AND OBJECTIVE

Previous studies on Danqi Piantan Jiaonang (DPJ, NeuroAid), a traditional Chinese medicine, in stroke patients showed promising results. Our aim was to determine the safety of DPJ in normal subjects and stroke patients through a series of studies assessing its immediate and long-term effects, alone and in combination with aspirin, on hematological, hemostatic, and biochemical parameters.

METHODS

We conducted 3 studies from December 2004 to May 2006. Study 1 was a case series which recruited 32 healthy volunteers who were given 2 oral doses of 4 DPJ capsules (0.4 g/capsule) 6 h apart. Study 2 was a randomized controlled trial of 22 healthy volunteers who received either 1 oral dose of aspirin 300 mg alone or a combination of 1 dose of aspirin 300 mg and 2 doses of 4 DPJ capsules taken 6 h apart. For both studies 1 and 2, hemostatic parameters (prothrombin time, activated partial thromboplastin time, fibrinogen, platelet aggregation, D-dimer) were tested at baseline, and after 2 and 8 h. Study 3 was a case series which recruited 10 patients with recent ischemic stroke (within 7 days) who were given 4 DPJ capsules taken orally 3 times a day for 1 month. Blood tests for hemostatic, hematological (complete blood count), and biochemical parameters (glucose, creatinine, alanine aminotransferase, aspartate transaminase, C-reactive protein) were performed at baseline, and after 1 and 4 weeks.

RESULTS

Apart from the expected changes in platelet aggregation in subjects taking aspirin, no significant differences were detected in hemostatic parameters at baseline, and 2 and 8 h after oral intake of DPJ alone or in combination with aspirin. Likewise, no significant differences were observed in hematological, hemostatic, and biochemical parameters at baseline, and after 1 and 4 weeks of oral intake of DPJ.

CONCLUSION

DPJ does not significantly modify hematological, hemostatic, and biochemical parameters in normal subjects and stroke patients.

Comparison of two neonatal ischemic injury models using magnetic resonance imaging

Using an 11.7-Tesla magnetic resonance imaging (MRI) scanner in 10-d-old rat pups we report on the evolution of injury over 28 d in a model of neonatal stroke (transient filament middle cerebral artery occlusion, tfMCAO) and a model of hypoxic-ischemic injury (Rice-Vannucci model, RVM). In both models, diffusion-weighted imaging (DWI) was more sensitive in the early detection of ischemia than T2-weighted imaging (T2WI). Injury volumes in both models were greater on d 1 for DWI and d 3 for T2WI, decreased over time and by d 28 T2WI injury volumes (tfMCAO 10.3% of ipsilateral hemisphere; RVM 23.9%) were definable. The distribution of injury with tfMCAO was confined to the vascular territory of the middle cerebral artery and a definable core and penumbra evolved over time. Ischemic injury in the RVM was more generalized and greater in cortical regions. Contralateral hemispheric involvement was only observed in the RVM. Our findings demonstrate that high-field MRI over extended periods of time is possible in a small animal model of neonatal brain injury and that the tfMCAO model should be used for studies of neonatal stroke and that the RVM does not reflect the vascular distribution of injury seen with focal ischemia.

Brief update on animal models of hypoxic-ischemic encephalopathy and neonatal stroke

The discovery of safe and effective therapies for perinatal hypoxia ischemia (HI) and stroke remains an unmet goal of neonatal-perinatal medicine. Because of the many developmental and functional differences between the neonatal brain and the adult brain, the ability to extrapolate adult data to the neonatal condition is very limited. For this reason, it is incumbent on scientists in the field of neonatal brain injury to address the questions of therapeutic efficacy of an array of potential therapies in a developmentally appropriate model. Toward that end, a number of new models of neonatal HI and stroke have been introduced recently. Additionally, some of the established models have been adapted to different species and different ages, giving scientists a greater choice of models for the study of neonatal HI and stroke. Many of these models are now also being used for functional and behavioral testing, an absolute necessity for preclinical therapeutic trials. This review focuses primarily on the newly developed models, recent adaptations to established models, and the studies of functional outcome that have been published since 2000.

Effects of daily environmental enrichment on memory deficits and brain injury following neonatal hypoxia-ischemia in the rat

Environmental enrichment (EE) results in improved learning and spatial memory, as well as attenuates morphological changes resulting from cerebral ischemia in adult animals. This study examined the effects of daily EE on memory deficits in the water maze and cerebral damage, assessed in the hippocampus and cerebral cortex, caused by neonatal hypoxia-ischemia. Male Wistar rats in the 7th postnatal day were submitted to the Levine-Rice model of neonatal hypoxia-ischemia (HI), comprising permanent occlusion of the right common carotid artery and a period of hypoxia (90 min, 8%O(2)-92%N(2)). Starting two weeks after the HI event, animals were stimulated by the enriched environment (1h/day for 9 weeks); subsequent to the stimulation, performance of animals in the water maze was assessed. HI resulted in spatial reference and working memory impairments that were completely reversed by EE. Following the behavioral study, animals were killed and the hippocampal volume and cortical area were estimated. There was a significant reduction of both hippocampal volume and cortical area, ipsilateral to arterial occlusion, in HI animals; environmental stimulation had no effect on these morphological measurements. Presented data indicate that stimulation by the daily environmental enrichment recovers spatial memory deficits caused by neonatal hypoxia-ischemia without affecting tissue atrophy in either hippocampus or cortex.

Hypoxic/Ischemic models in newborn piglet: Comparison of constant FiO2 versus variable FiO2 delivery

A comparison of a constant (continuous delivery of 4% FiO2) and a variable (initial 5% FiO2 with adjustments to induce low amplitude EEG (LAEEG) and hypotension) hypoxic/ischemic insult was performed to determine which insult was more effective in producing a consistent degree of survivable neuropathological damage in a newborn piglet model of perinatal asphyxia. We also examined which physiological responses contributed to this outcome. Thirty-nine 1-day-old piglets were subjected to either a constant hypoxic/ischemic insult of 30- to 37-min duration or a variable hypoxic/ischemic insult of 30-min low peak amplitude EEG (LAEEG <5 microV) including 10 min of low mean arterial blood pressure (MABP <70% of baseline). Control animals (n = 6) received 21% FiO2 for the duration of the experiment. At 72 h, the piglets were euthanased, their brains removed and fixed in 4% paraformaldehyde and assessed for hypoxic/ischemic injury by histological analysis. Based on neuropathology scores, piglets were grouped as undamaged or damaged; piglets that did not survive to 72 h were grouped separately as dead. The variable insult resulted in a greater number of piglets with neuropathological damage (undamaged = 12.5%, damaged = 68.75%, dead = 18.75%) while the constant insult resulted in a large proportion of undamaged piglets (undamaged = 50%, damaged = 22.2%, dead = 27.8%). A hypoxic insult varied to maintain peak amplitude EEG <5 microV results in a greater number of survivors with a consistent degree of neuropathological damage than a constant hypoxic insult. Physiological variables MABP, LAEEG, pH and arterial base excess were found to be significantly associated with neuropathological outcome.

Apoptosis in perinatal hypoxic-ischemic brain injury: how important is it and should it be inhibited?

The discovery of safe and effective therapies for perinatal hypoxia-ischemia (HI) and stroke remains an unmet goal of perinatal medicine. Hypothermia and antioxidants such as allopurinol are currently under investigation as treatments for neonatal HI. Drugs targeting apoptotic mechanisms are currently being studied in adult diseases such as cancer, stroke, and trauma and have been proposed as potential therapies for perinatal HI and stroke. Before developing antiapoptosis therapies for perinatal brain injury, we must determine whether this form of cell death plays an important role in these injuries and if the inhibition of these pathways promotes more benefit than harm. This review summarizes current evidence for apoptotic mechanisms in perinatal brain injury and addresses issues pertinent to the development of antiapoptosis therapies for perinatal HI and stroke.