Molecular and biochemical mechanisms of perinatal brain injury

Neonatal Encephalopathy: Novel Phenotypes and Genotypes Identified by Genome Sequencing

Background and Objectives

Neonatal encephalopathy (NE) is characterized by an abnormal level of consciousness with or without seizures in the neonatal period. It affects 1-6/1,000 live term newborns. We applied genome sequencing (GS) in term newborns with NE to investigate the underlying genetic causes.

Methods

We enrolled term newborns according to inclusion/exclusion criteria during their Neonatal Intensive Care admission. We performed GS trio and applied bioinformatic tools. We developed pipelines for manual filters. We applied in silico prediction tools, protein 3D modeling, and functional characterization to assess the pathogenicity of variants.

Results

Seventeen newborns fulfilled inclusion criteria. We identified 12 variants in 10 genes. We classified 4 variants in PPP2R5D, BCOR, CFL2, and SCN2A (previously established disease genes) as pathogenic/likely pathogenic; 7 variants in DST (previously established disease gene), STAB2, CELF4, SORCS2, CTNND2, and ASTN1 (5 candidate genes) as variants of uncertain significance (VUS); and one variant in STAB2 as likely benign. The CELF4 and ASTN1 copy number variants (CNVs) resulted in structural changes in protein 3D models. The functional characterization of SORCS2 VUS revealed disruption of SorCS2 dimer formation and confirmed its pathogenicity. The functional characterization of STAB2 variants updated their characterization from VUS/likely benign to benign. The CTNND2 VUS resulted in a shift in 3D protein structure. We were not able to perform protein 3D modeling and functional characterization of two DST VUS. We are not certain whether CTNND2 and DST variants may be causative of NE in our study.

Discussion

The diagnostic rate of research GS was 41% in our prospective study. We broaden the phenotypic spectrum of PPP2R5D-associated Hogue-Janssens syndrome 1, CFL2-associated nemaline myopathy 7, and BCOR-associated oculo-facio-cardio-dental syndrome to include NE and/or neonatal seizures. We identified 3 candidate genes (SORCS2, CELF4, ASTN1) that may cause NE. We believe that protein 3D modeling is an important tool to assess the pathogenicity of CNVs and may advance the discoveries of novel genetic diseases. However, functional characterization of missense variants is essential for discoveries of novel genetic diseases. It seems that GS can help identify more candidate genes compared with ES.

Distinguishing Laterality in Brain Injury in Rabbit Fetal Magnetic Resonance Imaging Using Novel Volume Rendering Techniques

INTRODUCTION

Our laboratory has been exploring the MRI detection of fetal brain injury, which previously provided a prognostic biomarker for newborn hypertonia in an animal model of cerebral palsy (CP). The biomarker relies on distinct patterns of diffusion-weighted imaging-defined apparent diffusion coefficient (ADC) in fetal brains during uterine hypoxia-ischemia (H-I). Despite the challenges posed by small brains and tissue acquisition, our objective was to differentiate between left and right brain ADC changes.

METHODS

A novel aspect involved utilizing three-dimensional rendering techniques to refine ADC measurements within spheroids encompassing fetal brain tissue. 25-day gestation age of rabbit fetuses underwent global hypoxia due to maternal uterine ischemia.

RESULTS

Successful differentiation of left and right brain regions was achieved in 28% of the fetal brains. Ordinal analysis revealed predominantly higher ADC on the left side compared to the right at baseline and across the entire time series. During H-I and reperfusion-reoxygenation, the right side exhibited a favored percentage change. Among these fetal brains, 73% exhibited the ADC pattern predictive of hypertonia. No significant differences between left and right sides were observed in patterns predicting hypertonia, except for one timepoint during H-I. This study also highlights a balance between left-sided and right-sided alterations within the population.

CONCLUSION

This study emphasizes the importance of investigating laterality and asymmetric hemispheric lesions for early diagnosis of brain injury, leading to CP. The technological limitations in obtaining a clear picture of the entire fetal brain for every fetus mirror the challenges encountered in human studies.

INTRODUCTION

Our laboratory has been exploring the MRI detection of fetal brain injury, which previously provided a prognostic biomarker for newborn hypertonia in an animal model of cerebral palsy (CP). The biomarker relies on distinct patterns of diffusion-weighted imaging-defined apparent diffusion coefficient (ADC) in fetal brains during uterine hypoxia-ischemia (H-I). Despite the challenges posed by small brains and tissue acquisition, our objective was to differentiate between left and right brain ADC changes.

METHODS

A novel aspect involved utilizing three-dimensional rendering techniques to refine ADC measurements within spheroids encompassing fetal brain tissue. 25-day gestation age of rabbit fetuses underwent global hypoxia due to maternal uterine ischemia.

RESULTS

Successful differentiation of left and right brain regions was achieved in 28% of the fetal brains. Ordinal analysis revealed predominantly higher ADC on the left side compared to the right at baseline and across the entire time series. During H-I and reperfusion-reoxygenation, the right side exhibited a favored percentage change. Among these fetal brains, 73% exhibited the ADC pattern predictive of hypertonia. No significant differences between left and right sides were observed in patterns predicting hypertonia, except for one timepoint during H-I. This study also highlights a balance between left-sided and right-sided alterations within the population.

CONCLUSION

This study emphasizes the importance of investigating laterality and asymmetric hemispheric lesions for early diagnosis of brain injury, leading to CP. The technological limitations in obtaining a clear picture of the entire fetal brain for every fetus mirror the challenges encountered in human studies.

Development of a New Scoring System in Higher Animals for Testing Cognitive Function in the Newborn Period: Effect of Prenatal Hypoxia-Ischemia

INTRODUCTION

Enhanced models for assessing cognitive function in the neonatal period are imperative in higher animals. Postnatal motor deficits, characteristic of cerebral palsy, emerge in newborn kits within our prenatal rabbit model of hypoxia-ischemia (HI). In humans, prenatal HI leads to intellectual disability and cerebral palsy. In a study examining cognitive function in newborn rabbits, we explored several questions. Is there a distinction between conditioned and unconditioned kits? Can the kits discern the human face or the laboratory coat? Do motorically normal kits, born after prenatal HI, exhibit cognitive deficits?

METHODS

The conditioning protocol was randomly assigned to kits from each litter. For conditioning, the same human, wearing a laboratory coat, fed the rabbit kits for 9 days before the cognitive test. The 6-arm radial maze was chosen for its simplicity and ease of use. Normally appearing kits, born after uterine ischemia at 79% or 92% term in New Zealand White rabbits, were compared to naïve kits. On postpartum day 22/23 or 29/30, the 6-arm maze helped determine if the kits recognized the original feeder from bystander (test 1) or the laboratory coat on bystander (test 2). The use of masks of feeder/bystander (test 3) assessed confounding cues. A weighted score was devised to address variability in entry to maze arms, time, and repeated-trial learning.

RESULTS

In conditioned kits, both naïve and HI kits exhibited a significant preference for the face of the feeder but not the laboratory coat. Cognitive deficits were minimal in normal-appearing HI kits.

CONCLUSION

The weighted score was amenable to statistical manipulation.

INTRODUCTION

Enhanced models for assessing cognitive function in the neonatal period are imperative in higher animals. Postnatal motor deficits, characteristic of cerebral palsy, emerge in newborn kits within our prenatal rabbit model of hypoxia-ischemia (HI). In humans, prenatal HI leads to intellectual disability and cerebral palsy. In a study examining cognitive function in newborn rabbits, we explored several questions. Is there a distinction between conditioned and unconditioned kits? Can the kits discern the human face or the laboratory coat? Do motorically normal kits, born after prenatal HI, exhibit cognitive deficits?

METHODS

The conditioning protocol was randomly assigned to kits from each litter. For conditioning, the same human, wearing a laboratory coat, fed the rabbit kits for 9 days before the cognitive test. The 6-arm radial maze was chosen for its simplicity and ease of use. Normally appearing kits, born after uterine ischemia at 79% or 92% term in New Zealand White rabbits, were compared to naïve kits. On postpartum day 22/23 or 29/30, the 6-arm maze helped determine if the kits recognized the original feeder from bystander (test 1) or the laboratory coat on bystander (test 2). The use of masks of feeder/bystander (test 3) assessed confounding cues. A weighted score was devised to address variability in entry to maze arms, time, and repeated-trial learning.

RESULTS

In conditioned kits, both naïve and HI kits exhibited a significant preference for the face of the feeder but not the laboratory coat. Cognitive deficits were minimal in normal-appearing HI kits.

CONCLUSION

The weighted score was amenable to statistical manipulation.

MR imaging and outcome in neonatal HIBD models are correlated with sex: the value of diffusion tensor MR imaging and diffusion kurtosis MR imaging

Objective

Hypoxic-ischemic encephalopathy can lead to lifelong morbidity and premature death in full-term newborns. Here, we aimed to determine the efficacy of diffusion kurtosis (DK) [mean kurtosis (MK)] and diffusion tensor (DT) [fractional anisotropy (FA), mean diffusion (MD), axial diffusion (AD), and radial diffusion (RD)] parameters for the early diagnosis of early brain histopathological changes and the prediction of neurodegenerative events in a full-term neonatal hypoxic-ischemic brain injury (HIBD) rat model.

Methods

The HIBD model was generated in postnatal day 7 Sprague-Dawley rats to assess the changes in DK and DT parameters in 10 specific brain structural regions involving the gray matter, white matter, and limbic system during acute (12 h) and subacute (3 d and 5 d) phases after hypoxic ischemia (HI), which were validated against histology. Sensory and cognitive parameters were assessed by the open field, novel object recognition, elevated plus maze, and CatWalk tests.

Results

Repeated-measures ANOVA revealed that specific brain structures showed similar trends to the lesion, and the temporal pattern of MK was substantially more varied than DT parameters, particularly in the deep gray matter. The change rate of MK in the acute phase (12 h) was significantly higher than that of DT parameters. We noted a delayed pseudo-normalization for MK. Additionally, MD, AD, and RD showed more pronounced differences between males and females after HI compared to MK, which was confirmed in behavioral tests. HI females exhibited anxiolytic hyperactivity-like baseline behavior, while the memory ability of HI males was affected in the novel object recognition test. CatWalk assessments revealed chronic deficits in limb gait parameters, particularly the left front paw and right hind paw, as well as poorer performance in HI males than HI females.

Conclusions

Our results suggested that DK and DT parameters were complementary in the immature brain and provided great value in assessing early tissue microstructural changes and predicting long-term neurobehavioral deficits, highlighting their ability to detect both acute and long-term changes. Thus, the various diffusion coefficient parameters estimated by the DKI model are powerful tools for early HIBD diagnosis and prognosis assessment, thus providing an experimental and theoretical basis for clinical treatment.

Therapeutic Effect of Nicotinamide Mononucleotide for Hypoxic-Ischemic Brain Injury in Neonatal Mice

SUMMARY STATEMENT

Neonatal hypoxia-ischemia reduces nicotinamide adenine dinucleotide (NAD+) and SIRT6 levels in the injured hippocampus.Hippocampal high mobility group box-1 (HMGB1) release is significantly increased after neonatal hypoxia-ischemia.Nicotinamide mononucleotide (NMN) treatment normalizes hippocampal NAD+ and SIRT6 levels, with significant decrease in caspase-3 activity and HMGB1 release.NMN improves early developmental behavior, as well as motor and memory function.

Imaging of Hypoxic-Ischemic Injury (in the Era of Cooling)

Hypoxic-ischemic injury (HII) is a major worldwide contributor of term neonatal mortality and long-term morbidity. At present, therapeutic hypothermia is the only therapy that has demonstrated efficacy in reducing severe disability or death in infants with moderate to severe encephalopathy. MRI and MRS performed during the first week of life are adequate to assess brain injury and offer prognosis. Patterns of injury will depend on the gestation age of the neonate, as well as the degree of hypotension.

Fetal Neuroprotective Strategies: Therapeutic Agents and Their Underlying Synaptic Pathways

Synaptic signaling is integral for proper brain function. During fetal development, exposure to inflammation or mild hypoxic-ischemic insult may lead to synaptic changes and neurological damage that impairs future brain function. Preterm neonates are most susceptible to these deleterious outcomes. Evaluating clinically used and novel fetal neuroprotective measures is essential for expanding treatment options to mitigate the short and long-term consequences of fetal brain injury. Magnesium sulfate is a clinical fetal neuroprotective agent utilized in cases of imminent preterm birth. By blocking N-methyl-D-aspartate receptors, magnesium sulfate reduces glutamatergic signaling, which alters calcium influx, leading to a decrease in excitotoxicity. Emerging evidence suggests that melatonin and N-acetyl-L-cysteine (NAC) may also serve as novel putative fetal neuroprotective candidates. Melatonin has important anti-inflammatory and antioxidant properties and is a known mediator of synaptic plasticity and neuronal generation. While NAC acts as an antioxidant and a precursor to glutathione, it also modulates the glutamate system. Glutamate excitotoxicity and dysregulation can induce perinatal preterm brain injury through damage to maturing oligodendrocytes and neurons. The improved drug efficacy and delivery of the dendrimer-bound NAC conjugate provides an opportunity for enhanced pharmacological intervention. Here, we review recent literature on the synaptic pathways underlying these therapeutic strategies, discuss the current gaps in knowledge, and propose future directions for the field of fetal neuroprotective agents.

Use of Melatonin in Oxidative Stress Related Neonatal Diseases

Reactive oxygen species have a crucial role in the pathogenesis of perinatal diseases. Exposure to inflammation, infections, or high oxygen concentrations is frequent in preterm infants, who have high free iron levels that enhance toxic radical generation and diminish antioxidant defense. The peculiar susceptibility of newborns to oxidative stress supports the prophylactic use of melatonin in preventing or decreasing oxidative stress-mediated diseases. Melatonin, an effective direct free-radical scavenger, easily diffuses through biological membranes and exerts pleiotropic activity everywhere. Multiple investigations have assessed the effectiveness of melatonin to reduce the “oxygen radical diseases of newborn” including perinatal brain injury, sepsis, chronic lung disease (CLD), and necrotizing enterocolitis (NEC). Further studies are still awaited to test melatonin activity during perinatal period.

Silencing of long non‑coding antisense RNA brain‑derived neurotrophic factor attenuates hypoxia/ischemia‑induced neonatal brain injury

Hypoxic/ischemic (HI) brain damage (HIBD) is a major cause of acute neonatal brain injury, leading to high mortality and serious neurological deficits. The antisense RNA of brain-derived neurotrophic factor (BDNF-AS) is transcribed from the opposite strand of the BDNF gene. The aim of the present study was to investigate the role of BDNF-AS in HI-induced neuronal cell injury in vivo and in vitro. Reverse transcription-quantitative PCR (RT-qPCR) assays indicated that BDNF-AS expression was significantly upregulated in HI-injured neonatal brains and hippocampal neurons. However, BDNF expression was downregulated in HI-injured neonatal brains and hippocampal neurons. Cell Counting Kit-8 assays, Hoechst staining, calcein-AM/PI staining, immunostaining, water maze tests and rotarod tests demonstrated that BDNF-AS silencing protected against hypoxia-induced primary hippocampal neuron injury in vitro and HI-induced brain injury in vivo. Mechanistically, RT-qPCR assays and western blotting indicated that BDNF-AS silencing led to increased expression of BDNF and activated the BDNF-mediated signaling pathway, as demonstrated by increased expression levels of BDNF, phosphorylated-Akt and phosphorylated-tropomyosin receptor kinase B. Collectively, the present study provides important insights into the pathogenesis of HIBD, and it was indicated that BDNF-AS silencing may be a promising approach for the treatment of neonatal HIBD.

Mining multi-site clinical data to develop machine learning MRI biomarkers: application to neonatal hypoxic ischemic encephalopathy

BACKGROUND

Secondary and retrospective use of hospital-hosted clinical data provides a time- and cost-efficient alternative to prospective clinical trials for biomarker development. This study aims to create a retrospective clinical dataset of Magnetic Resonance Images (MRI) and clinical records of neonatal hypoxic ischemic encephalopathy (HIE), from which clinically-relevant analytic algorithms can be developed for MRI-based HIE lesion detection and outcome prediction.

METHODS

This retrospective study will use clinical registries and big data informatics tools to build a multi-site dataset that contains structural and diffusion MRI, clinical information including hospital course, short-term outcomes (during infancy), and long-term outcomes (~ 2 years of age) for at least 300 patients from multiple hospitals.

DISCUSSION

Within machine learning frameworks, we will test whether the quantified deviation from our recently-developed normative brain atlases can detect abnormal regions and predict outcomes for individual patients as accurately as, or even more accurately, than human experts. Trial Registration Not applicable. This study protocol mines existing clinical data thus does not meet the ICMJE definition of a clinical trial that requires registration.

Potential biomarkers for neuroinflammation and neurodegeneration at short and long term after neonatal hypoxic-ischemic insult in rat

BACKGROUND

Hypoxic-ischemic (HI) encephalopathy causes life-long morbidity and premature mortality in term neonates. Therapies in addition to whole-body cooling are under development to treat the neonate at risk for HI encephalopathy, but are not a quickly measured serum inflammatory or neuronal biomarkers to rapidly and accurately identify brain injury in order to follow the efficacy of therapies.

METHODS

In order to identify potential biomarkers for early inflammatory and neurodegenerative events after neonatal hypoxia-ischemia, both male and female Wistar rat pups at postnatal day 7 (P7) were used and had their right carotid artery permanently doubly occluded and exposed to 8% oxygen for 90 min. Sensory and cognitive parameters were assessed by open field, rotarod, CatWalk, and Morris water maze (MWM) test. Plasma and CSF biomarkers were investigated on the acute (24 h and 72 h) and chronic phase (4 weeks). Brains were assessed for gene expression analysis by quantitative RT-PCR Array.

RESULTS

We found a delay of neurological reflex maturation in HI rats. We observed anxiolytic-like baseline behavior in males more than females following HI injury. HI rats held on the rotarod for a shorter time comparing to sham. HI injury impaired spatial learning ability on MWM test. The CatWalk assessment demonstrated a long-term deficit in gait parameters related to the hind paw. Proinflammatory biomarkers such as IL-6 in plasma and CCL2 and TNF-α in CSF showed an upregulation at 24 h after HI while other cytokines, such as IL-17A and CCL5, were upregulated after 72 h in CSF. At 24 h post-injury, we observed an increase of Edn1, Hif1-α, and Mmp9 mRNA levels in the ipsilateral vs the contralateral hemisphere of HI rats. An upregulation of genes involved with clotting and hematopoietic processes was observed 72 h post-injury.

CONCLUSIONS

Our work showed that, in the immature brain, the HI injury induced an early increased production of several proinflammatory mediators detectable in plasma and CSF, followed by tissue damage in the hypoxic hemisphere and short-term as well as long-lasting neurobehavioral deficits.

Traumatic injury in female Drosophila melanogaster affects the development and induces behavioral abnormalities in the offspring

Traumatic injury (TI) during pregnancy increases the risk for developing neurological disorders in the infants. These disorders are a major concern for the well-being of children born after TI during pregnancy. TI during pregnancy may result in preterm labor and delivery, abruptio placentae, and/or fetomaternal hemorrhage. Drosophila melanogaster (fruit fly) is a widely used model to study brain and behavioral disorders in humans. In this study, we analyzed the effects of TI to female fruit flies on the development timing of larvae, social interaction and the behavior of offspring flies. TI to the female flies was found to affect the development of larvae and the behavior of offspring flies. There was a significant increase in the length of larvae delivered by traumatically injured maternal flies as compared to larvae from control maternal flies (without TI). The pupae formation from larvae, and the metamorphosis of pupae to the first generation of flies were faster in the TI group than the control group. Negative geotaxis and distance of the fly to its nearest neighbor are parameters of behavioral assessment in fruit flies. Negative geotaxis significantly decreased in the first generation of both male (p = 0.0021) and female (p = 0.0426) flies. The distance between the first generation of flies to its nearest neighbor was shorter in both male and female offspring flies in the TI group as compared to control group flies. These results indicate that TI to the female flies affected the development of larvae and resulted in early delivery, impaired social interaction and behavioral alterations in the offspring.

Fetal inflammation is associated with persistent systemic and hippocampal inflammation and dysregulation of hippocampal glutamatergic homeostasis

BACKGROUND

Inflammation is a major cause of preterm birth and often results in a fetal inflammatory response syndrome (FIRS). Preterm infants with FIRS have a higher childhood incidence of neurodevelopmental disability than preterm infants without FIRS. The mechanisms connecting FIRS to neurodevelopmental disability in formerly preterm infants are not fully understood, but the effect on premature gray matter may have an important role.

METHODS

Fetal rats were exposed to intra-amniotic (i.a.) LPS 2 days prior to birth to model FIRS. On postnatal day 7, expression of inflammatory mediators was measured in the liver, lung, and brain. Activation of microglia and expression of glutamatergic receptor subunits and transporters were measured in the hippocampus and cortex.

RESULTS

LPS caused persistent systemic inflammatory mediators gene expression. In the brain, there was corresponding activation of microglia in the hippocampus and cortex. Expression of inflammatory mediators persisted in the hippocampus, but not the cortex, and was associated with altered glutamatergic receptor subunits and transporters.

CONCLUSION

Hippocampal inflammation and dysregulation of glutamate metabolism persisted well into the postnatal period following i.a. LPS. Poor neurodevelopmental outcomes after FIRS in preterm infants may result in part through glutamatergically driven gray matter injury to the neonatal hippocampus.

Preventing childhood and lifelong disability: Maternal dietary supplementation for perinatal brain injury

The majority of brain injuries that lead to cerebral palsy, developmental disability, and mental health disorders have their onset in utero. These lifelong conditions come with great economic and emotional burden as they impact function in nearly all domains of affected individuals' lives. Unfortunately, current therapeutic options are limited. There remains a focus on rescue, rehabilitation, and regeneration after the injury has occurred, rather than aiming to prevent the initial injury. Prevention would imply treating the mother during pregnancy to alter the fetal environment and in turn, treat the fetus. Fear of harming the developing fetus remains as a result of errors of the past such as the release of thalidomide. In this review, we outline evidence from animal studies and clinical trials that have explored maternal dietary supplementation with natural health products (including nutraceuticals and functional foods) for perinatal brain injury prevention. Namely, we discuss magnesium sulphate, creatine, choline, melatonin, resveratrol and broccoli sprouts/sulforaphane. Although clinical trials have only been completed in this realm for magnesium sulphate, results in animal models have been promising, suggesting that this is a productive avenue for further research. Natural health products may provide safe, effective, affordable, and easily accessible prevention of fetal brain injury and resulting lifelong disabilities.

NMNAT3 is protective against the effects of neonatal cerebral hypoxia-ischemia

OBJECTIVE

To determine whether the NAD+ biosynthetic protein, nicotinamide mononucleotide adenylyltransferase-3 (NMNAT3), is a neuroprotective inducible enzyme capable of decreasing cerebral injury after neonatal hypoxia-ischemia (H-I) and reducing glutamate receptor-mediated excitotoxic neurodegeneration of immature neurons.

METHODS

Using NMNAT3-overexpressing mice we investigated whether increases in brain NMNAT3 reduced cerebral tissue loss following H-I. We then employed biochemical methods from injured neonatal brains to examine the inducibility of NMNAT3 and the mechanism of NMNAT3-dependent neuroprotection. Using AAV8-mediated vectors for in vitro neuronal NMNAT3 knockdown, we then examine the endogenous role of this protein on immature neuronal survival prior and following NMDA receptor-mediated excitotoxicity.

RESULTS

NMNAT3 mRNA and protein levels increased after neonatal H-I. In addition, NMNAT3 overexpression decreased cortical and hippocampal tissue loss 7 days following injury. We further show that the NMNAT3 neuroprotective mechanism involves a decrease in calpastatin degradation, and a decrease in caspase-3 activity and calpain-mediated cleavage. Conversely, NMNAT3 knockdown of cortical and hippocampal neurons in vitro caused neuronal degeneration and increased excitotoxic cell death. The neurodegenerative effects of NMNAT3 knockdown were counteracted by exogenous upregulation of NMNAT3.

CONCLUSIONS

Our observations provide new insights into the neuroprotective mechanisms of NMNATs in the injured developing brain, adding NMNAT3 as an important neuroprotective enzyme in neonatal H-I via inhibition of apoptotic and necrotic neurodegeneration. Interestingly, we find that endogenous NMNAT3 is an inducible protein important for maintaining the survival of immature neurons. Future studies aimed at uncovering the mechanisms of NMNAT3 upregulation and neuroprotection may offer new therapies against the effects of hypoxic-ischemic encephalopathy.

Antenatal and intrapartum interventions for preventing cerebral palsy: an overview of Cochrane systematic reviews

BACKGROUND

Cerebral palsy is an umbrella term encompassing disorders of movement and posture, attributed to non-progressive disturbances occurring in the developing fetal or infant brain. As there are diverse risk factors and causes, no one strategy will prevent all cerebral palsy. Therefore, there is a need to systematically consider all potentially relevant interventions for their contribution to prevention.

OBJECTIVES

To summarise the evidence from Cochrane reviews regarding the effects of antenatal and intrapartum interventions for preventing cerebral palsy.

METHODS

We searched the Cochrane Database of Systematic Reviews on 7 August 2016, for reviews of antenatal or intrapartum interventions reporting on cerebral palsy. Two authors assessed reviews for inclusion, extracted data, assessed review quality, using AMSTAR and ROBIS, and quality of the evidence, using the GRADE approach. We organised reviews by topic, and summarised findings in text and tables. We categorised interventions as effective (high-quality evidence of effectiveness); possibly effective (moderate-quality evidence of effectiveness); ineffective (high-quality evidence of harm or of lack of effectiveness); probably ineffective (moderate-quality evidence of harm or of lack of effectiveness); and no conclusions possible (low- to very low-quality evidence).

MAIN RESULTS

We included 15 Cochrane reviews. A further 62 reviews pre-specified the outcome cerebral palsy in their methods, but none of the included randomised controlled trials (RCTs) reported this outcome. The included reviews were high quality and at low risk of bias. They included 279 RCTs; data for cerebral palsy were available from 27 (10%) RCTs, involving 32,490 children. They considered interventions for: treating mild to moderate hypertension (two) and pre-eclampsia (two); diagnosing and preventing fetal compromise in labour (one); preventing preterm birth (four); preterm fetal maturation or neuroprotection (five); and managing preterm fetal compromise (one). Quality of evidence ranged from very low to high. Effective interventions: high-quality evidence of effectiveness There was a reduction in cerebral palsy in children born to women at risk of preterm birth who received magnesium sulphate for neuroprotection of the fetus compared with placebo (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.54 to 0.87; five RCTs; 6145 children). Probably ineffective interventions: moderate-quality evidence of harm There was an increase in cerebral palsy in children born to mothers in preterm labour with intact membranes who received any prophylactic antibiotics versus no antibiotics (RR 1.82, 95% CI 0.99 to 3.34; one RCT; 3173 children). There was an increase in cerebral palsy in children, who as preterm babies with suspected fetal compromise, were born immediately compared with those for whom birth was deferred (RR 5.88, 95% CI 1.33 to 26.02; one RCT; 507 children). Probably ineffective interventions: moderate-quality evidence of lack of effectiveness There was no clear difference in the presence of cerebral palsy in children born to women at risk of preterm birth who received repeat doses of corticosteroids compared with a single course (RR 1.03, 95% CI 0.71 to 1.50; four RCTs; 3800 children). No conclusions possible: low- to very low-quality evidence Low-quality evidence found there was a possible reduction in cerebral palsy for children born to women at risk of preterm birth who received antenatal corticosteroids for accelerating fetal lung maturation compared with placebo (RR 0.60, 95% CI 0.34 to 1.03; five RCTs; 904 children). There was no clear difference in the presence of cerebral palsy with interventionist care for severe pre-eclampsia versus expectant care (RR 6.01, 95% CI 0.75 to 48.14; one RCT; 262 children); magnesium sulphate for pre-eclampsia versus placebo (RR 0.34, 95% CI 0.09 to 1.26; one RCT; 2895 children); continuous cardiotocography for fetal assessment during labour versus intermittent auscultation (average RR 1.75, 95% CI 0.84 to 3.63; two RCTs; 13,252 children); prenatal progesterone for prevention of preterm birth versus placebo (RR 0.14, 95% CI 0.01 to 3.48; one RCT; 274 children); and betamimetics for inhibiting preterm labour versus placebo (RR 0.19, 95% CI 0.02 to 1.63; one RCT; 246 children).Very low-quality found no clear difference for the presence of cerebral palsy with any antihypertensive drug (oral beta-blockers) for treatment of mild to moderate hypertension versus placebo (RR 0.33, 95% CI 0.01 to 8.01; one RCT; 110 children); magnesium sulphate for prevention of preterm birth versus other tocolytic agents (RR 0.13, 95% CI 0.01 to 2.51; one RCT; 106 children); and vitamin K and phenobarbital prior to preterm birth for prevention of neonatal periventricular haemorrhage versus placebo (RR 0.77, 95% CI 0.33 to 1.76; one RCT; 299 children).

AUTHORS' CONCLUSIONS

This overview summarises evidence from Cochrane reviews on the effects of antenatal and intrapartum interventions on cerebral palsy, and can be used by researchers, funding bodies, policy makers, clinicians and consumers to aid decision-making and evidence translation. We recommend that readers consult the included Cochrane reviews to formally assess other benefits or harms of included interventions, including impacts on risk factors for cerebral palsy (such as the reduction in intraventricular haemorrhage for preterm babies following exposure to antenatal corticosteroids).Magnesium sulphate for women at risk of preterm birth for fetal neuroprotection can prevent cerebral palsy. Prophylactic antibiotics for women in preterm labour with intact membranes, and immediate rather than deferred birth of preterm babies with suspected fetal compromise, may increase the risk of cerebral palsy. Repeat doses compared with a single course of antenatal corticosteroids for women at risk of preterm birth do not clearly impact the risk of cerebral palsy.Cerebral palsy is rarely diagnosed at birth, has diverse risk factors and causes, and is diagnosed in approximately one in 500 children. To date, only a small proportion of Cochrane reviews assessing antenatal and intrapartum interventions have been able to report on this outcome. There is an urgent need for long-term follow-up of RCTs of interventions addressing risk factors for cerebral palsy, and consideration of the use of relatively new interim assessments (including the General Movements Assessment). Such RCTs must be rigorous in their design, and aim for consistency in cerebral palsy outcome measurement and reporting to facilitate pooling of data, to focus research efforts on prevention.

Functional Role of Intracellular Calcium Receptor Inositol 1,4,5-Trisphosphate Type 1 in Rat Hippocampus after Neonatal Anoxia

Anoxia is one of the most prevalent causes of neonatal morbidity and mortality, especially in preterm neonates, constituting an important public health problem due to permanent neurological sequelae observed in patients. Oxygen deprivation triggers a series of simultaneous cascades, culminating in cell death mainly located in more vulnerable metabolic brain regions, such as the hippocampus. In the process of cell death by oxygen deprivation, cytosolic calcium plays crucial roles. Intracellular inositol 1,4,5-trisphosphate receptors (IP3Rs) are important regulators of cytosolic calcium levels, although the role of these receptors in neonatal anoxia is completely unknown. This study focused on the functional role of inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) in rat hippocampus after neonatal anoxia. Quantitative real-time PCR revealed a decrease of IP3R1 gene expression 24 hours after neonatal anoxia. We detected that IP3R1 accumulates specially in CA1, and this spatial pattern did not change after neonatal anoxia. Interestingly, we observed that anoxia triggers translocation of IP3R1 to nucleus in hippocampal cells. We were able to observe that anoxia changes distribution of IP3R1 immunofluorescence signals, as revealed by cluster size analysis. We next examined the role of IP3R1 in the neuronal cell loss triggered by neonatal anoxia. Intrahippocampal injection of non-specific IP3R1 blocker 2-APB clearly reduced the number of Fluoro-Jade C and Tunel positive cells, revealing that activation of IP3R1 increases cell death after neonatal anoxia. Finally, we aimed to disclose mechanistics of IP3R1 in cell death. We were able to determine that blockade of IP3R1 did not reduced the distribution and pixel density of activated caspase 3-positive cells, indicating that the participation of IP3R1 in neuronal cell loss is not related to classical caspase-mediated apoptosis. In summary, this study may contribute to new perspectives in the investigation of neurodegenerative mechanisms triggered by oxygen deprivation.

Maternal inflammation leads to impaired glutamate homeostasis and up-regulation of glutamate carboxypeptidase II in activated microglia in the fetal/newborn rabbit brain

Astrocyte dysfunction and excessive activation of glutamatergic systems have been implicated in a number of neurologic disorders, including periventricular leukomalacia (PVL) and cerebral palsy (CP). However, the role of chorioamnionitis on glutamate homeostasis in the fetal and neonatal brains is not clearly understood. We have previously shown that intrauterine endotoxin administration results in intense microglial 'activation' and increased pro-inflammatory cytokines in the periventricular region (PVR) of the neonatal rabbit brain. In this study, we assessed the effect of maternal inflammation on key components of the glutamate pathway and its relationship to astrocyte and microglial activation in the fetal and neonatal New Zealand white rabbit brain. We found that intrauterine endotoxin exposure at gestational day 28 (G28) induced acute and prolonged glutamate elevation in the PVR of fetal (G29, 1day post-injury) and postnatal day 1 (PND1, 3days post-injury) brains along with prominent morphological changes in the astrocytes (soma hypertrophy and retracted processes) in the white matter tracts. There was a significant increase in glutaminase and N-Methyl-d-Aspartate receptor (NMDAR) NR2 subunit expression along with decreased glial L-glutamate transporter 1 (GLT-1) in the PVR at G29, that would promote acute dysregulation of glutamate homeostasis. This was accompanied with significantly decreased TGF-β1 at PND1 in CP kits indicating ongoing neuroinflammation. We also show for the first time that glutamate carboxypeptidase II (GCPII) was significantly increased in the activated microglia at the periventricular white matter area in both G29 and PND1 CP kits. This was confirmed by in vitro studies demonstrating that LPS activated primary microglia markedly upregulate GCPII enzymatic activity. These results suggest that maternal intrauterine endotoxin exposure results in early onset and long-lasting dysregulation of glutamate homeostasis, which may be mediated by impaired astrocyte function and GCPII upregulation in activated microglia.

HMGB1 Translocation After Ischemia in the Ovine Fetal Brain

Inflammation contributes to the evolution of hypoxic-ischemic (HI) brain injury. High-mobility group box-1 (HMGB1) is a nuclear protein that is translocated from the nucleus and released after ischemia in adult rodents and thereby initiates inflammatory responses. However, there is very little information regarding the effects of HI on HMGB1 in immature brains. To investigate the effects of HI on HMGB1 in the term-equivalent fetal brain, ovine fetuses at 127 days gestation were studied after 30 minutes of carotid occlusion. Groups were sham-control and ischemia with 48 hours and ischemia with 72 hours of reperfusion. By immunohistochemistry, HMGB1 was found to be localized primarily in cell nuclei and partially in cytoplasmic compartments in the cerebral cortex of controls. Ischemia increased the area fraction of neuronal cells with cytoplasmic HMGB1 staining, and Western immunoblot revealed that cytosolic HMGB1 expression increased after ischemia (p < 0.05) and decreased in nuclei in ischemic versus the sham-control brains (p < 0.05). These data indicate that HMGB1 translocates from the nuclear to cytosolic compartments after ischemic brain injury in fetal sheep. This translocation may enable the action of HMGB1 as a proinflammatory cytokine that contributes to HI injury in the developing brain.

Melatonin for women in pregnancy for neuroprotection of the fetus

BACKGROUND

Melatonin is an antioxidant with anti-inflammatory and anti-apoptotic effects. Animal studies have supported a fetal neuroprotective role for melatonin when administered maternally. It is important to assess whether melatonin, given to the mother, can reduce the risk of neurosensory disabilities (including cerebral palsy) and death, associated with fetal brain injury, for the preterm or term compromised fetus.

OBJECTIVES

To assess the effects of melatonin when used for neuroprotection of the fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2016).

SELECTION CRITERIA

We planned to include randomised controlled trials and quasi-randomised controlled trials comparing melatonin given to women in pregnancy (regardless of the route, timing, dose and duration of administration) for fetal neuroprotection with placebo, no treatment, or with an alternative agent aimed at providing fetal neuroprotection. We also planned to include comparisons of different regimens for administration of melatonin.

DATA COLLECTION AND ANALYSIS

Two review authors planned to independently assess trial eligibility, trial quality and extract the data.

MAIN RESULTS

We found no randomised trials for inclusion in this review. One study is ongoing.

AUTHORS' CONCLUSIONS

As we did not identify any randomised trials for inclusion in this review, we are unable to comment on implications for practice at this stage.Although evidence from animals studies has supported a fetal neuroprotective role for melatonin when administered to the mother during pregnancy, no trials assessing melatonin for fetal neuroprotection in pregnant women have been completed to date. However, there is currently one ongoing randomised controlled trial (with an estimated enrolment target of 60 pregnant women) which examines the dose of melatonin, administered to women at risk of imminent very preterm birth (less than 28 weeks' gestation) required to reduce brain damage in the white matter of the babies that were born very preterm.Further high-quality research is needed and research efforts should directed towards trials comparing melatonin with either no intervention (no treatment or placebo), or with alternative agents aimed at providing fetal neuroprotection (such as magnesium sulphate for the very preterm infant). Such trials should evaluate maternal and infant short- and longer-term outcomes (including neurosensory disabilities such as cerebral palsy), and consider the costs of care.

Delayed effect of prenatal exposure to hypoxia on the susceptibility of rats to electric seizures

We studied the delayed effects of prenatal exposure to hypoxia on the susceptibility of rats to seizures. The later was estimated using graded electroshock. The experiments were performed in two groups of 1.5-year-old male Wistar rats. The experimental group consisted of the animals that were exposed to hypoxia on day 14 of prenatal development, and the control group consisted of the animals that developed under the normal conditions. In the rats subjected to prenatal hypoxia, seizure episodes induced by weak currents in the range of 10-40 mA and their average duration were more pronounced as compared to the control animals.

Antioxidant Treatments Recover the Alteration of Auditory-Evoked Potentials and Reduce Morphological Damage in the Inferior Colliculus after Perinatal Asphyxia in Rat

Maturation of the auditory pathway is dependent on the central nervous system myelination and it can be affected by pathologies such as neonatal hypoxic ischemic (HI) encephalopathy. Our aim was to evaluate the functional integrity of the auditory pathway and to visualize, by histological and cellular methods, the damage to the brainstem using a neonatal rat model of HI brain injury. To carry out this morphofunctional evaluation, we studied the effects of the administration of the antioxidants nicotine, melatonin, resveratrol and docosahexaenoic acid after hypoxia-ischemia on the inferior colliculus and the auditory pathway. We found that the integrity of the auditory pathway in the brainstem was altered as a consequence of the HI insult. Thus, the auditory brainstem response (ABR) showed increased I-V and III-V wave latencies. At a histological level, HI altered the morphology of the inferior colliculus neurons, astrocytes and oligodendricytes, and at a molecular level, the mitochondria membrane potential and integrity was altered during the first hours after the HI and reactive oxygen species (ROS) activity is increased 12 h after the injury in the brainstem. Following antioxidant treatment, ABR interpeak latency intervals were restored and the body and brain weight was recovered as well as the morphology of the inferior colliculus that was similar to the control group. Our results support the hypothesis that antioxidant treatments have a protective effect on the functional changes of the auditory pathway and on the morphological damage which occurs after HI insult.

Neonatal anoxia in rats: hippocampal cellular and subcellular changes related to cell death and spatial memory

Neonatal anoxia in rodents has been used to understand brain changes and cognitive dysfunction following asphyxia. This study investigated the time-course of cellular and subcellular changes and hippocampal cell death in a non-invasive model of anoxia in neonatal rats, using Terminal deoxynucleotidyl transferase-mediated dUTP Nick End Labeling (TUNEL) to reveal DNA fragmentation, Fluoro-Jade® B (FJB) to show degenerating neurons, cleaved caspase-3 immunohistochemistry (IHC) to detect cells undergoing apoptosis, and transmission electron microscopy (TEM) to reveal fine ultrastructural changes related to cell death. Anoxia was induced by exposing postnatal day 1 (P1) pups to a flow of 100% gaseous nitrogen for 25 min in a chamber maintained at 37 °C. Control rats were similarly exposed to this chamber but with air flow instead of nitrogen. Brain changes following anoxia were evaluated at postnatal days 2, 14, 21 and 60 (P2, P14, P21 and P60). In addition, spatial reference memory following anoxia and control treatments was evaluated in the Morris water maze, starting at P60. Compared to their respective controls, P2 anoxic rats exhibited (1) higher TUNEL labeling in cornus ammonis (CA) 1 and the dentate gyrus (DG), (2) higher FJB-positive cells in the CA2-3, and (3) somato-dendritic swelling, mitochondrial injury and chromatin condensation in irregular bodies, as well as other subcellular features indicating apoptosis, necrosis, autophagy and excitotoxicity in the CA1, CA2-3 and DG, as revealed by TEM. At P14, P21 and P60, both groups showed small numbers of TUNEL-positive and FJB-positive cells. Stereological analysis at P2, P14, P21 and P60 revealed a lack of significant differences in cleaved caspase-3 IHC between anoxic and control subjects. These results suggest that the type of hippocampal cell death following neonatal anoxia is likely independent of caspase-3 activation. Neonatal anoxia induced deficits in acquisition and performance of spatial reference memory in the Morris water maze task. Compared to control subjects, anoxic animals exhibited increased latencies and path lengths to reach the platform, as well as decreased searching specifically for the platform location. In contrast, no significant differences were observed for swimming speeds and frequency within the target quadrant. Together, these behavioral results indicate that the poorer performance by anoxic subjects is related to spatial memory deficits and not to sensory or motor deficits. Therefore, this model of neonatal anoxia in rats induces hippocampal changes that result in cell losses and impaired hippocampal function, and these changes are likely related to spatial memory deficits in adulthood.

Effect of transient maternal hypotension on apoptotic cell death in foetal rat brain

BACKGROUND

Intrauterine perfusion insufficiency induced by transient maternal hypotension has been reported to be associated with foetal brain malformations. However, the effects of maternal hypotension on apoptotic processes in the foetal brain have not been investigated experimentally during the intrauterine period.

AIMS

The aim of this study was to investigate the effects of transient maternal hypotension on apoptotic cell death in the intrauterine foetal brain.

STUDY DESIGN

Animal experimentation.

METHODS

Three-month-old female Wistar albino rats were allocated into four groups (n=5 each). The impact of hypoxic/ischemic injury induced by transient maternal hypotension on the 15th day of pregnancy (late gestation) in rats was investigated at 48 (H17 group) or 96 hours (H19 group) after the insult. Control groups underwent the same procedure except for induction of hypotension (C17 and H17 groups). Brain sections of one randomly selected foetus from each pregnant rat were histopathologically evaluated for hypoxic/ischemic injury in the metencephalon, diencephalon, and telencephalon by terminal transferase-mediated dUTP nick end labelling and active cysteine-dependent aspartate-directed protease-3 (caspase-3) positivity for cell death.

RESULTS

The number of terminal transferase-mediated dUTP nick end labelling (+) cells in all the areas examined was comparable in both hypotension and control groups. The H17 group had active caspase-3 (+) cells in the metencephalon and telencephalon, sparing diencephalon, whereas the C19 and H19 groups had active caspase-3 (+) cells in all three regions. The number of active caspase-3 (+) cells in the telencephalon in the H19 group was higher compared with the metencephalon and diencephalon and compared with H17 group (p<0.05).

CONCLUSION

Our results suggest that prenatal hypoxic/ischemic injury triggers apoptotic mechanisms. Therefore, blockade of apoptotic pathways, considering the time pattern of the insult, may constitute a potential neuroprotective approach for the detrimental effects of prenatal hypoperfusion.

Protective role of melatonin in neonatal diseases

Oxidative stress contributes to the severity of several newborn conditions to the extent that Saugstad coined the phrase "oxygen radical diseases of neonatology." In order to counteract free radicals damage many strategies to augment antioxidant status in ill-term and preterm infants have been proposed and several medications have been experimented with mixed results. Several studies have tested the efficacy of melatonin to counteract oxidative damage in diseases of newborns such as chronic lung disease, perinatal brain injury, necrotizing enterocolitis, and retinopathy of prematurity, giving promising results. The peculiar perinatal susceptibility to oxidative stress indicates that prophylactic use of antioxidants as melatonin could help to prevent or at least reduce oxidative stress related diseases in newborns. However, more studies are needed to confirm these beneficial effects.

Death associated protein kinases: molecular structure and brain injury

Perinatal brain damage underlies an important share of motor and neurodevelopmental disabilities, such as cerebral palsy, cognitive impairment, visual dysfunction and epilepsy. Clinical, epidemiological, and experimental studies have revealed that factors such as inflammation, excitotoxicity and oxidative stress contribute considerably to both white and grey matter injury in the immature brain. A member of the death associated protein kinase (DAPk) family, DAPk1, has been implicated in cerebral ischemic damage, whereby DAPk1 potentiates NMDA receptor-mediated excitotoxicity through interaction with the NR2BR subunit. DAPk1 also mediate a range of activities from autophagy, membrane blebbing and DNA fragmentation ultimately leading to cell death. DAPk mRNA levels are particularly highly expressed in the developing brain and thus, we hypothesize that DAPk1 may play a role in perinatal brain injury. In addition to reviewing current knowledge, we present new aspects of the molecular structure of DAPk domains, and relate these findings to interacting partners of DAPk1, DAPk-regulation in NMDA-induced cerebral injury and novel approaches to blocking the injurious effects of DAPk1.

The endogenous regenerative capacity of the damaged newborn brain: boosting neurogenesis with mesenchymal stem cell treatment

Neurogenesis continues throughout adulthood. The neurogenic capacity of the brain increases after injury by, e.g., hypoxia-ischemia. However, it is well known that in many cases brain damage does not resolve spontaneously, indicating that the endogenous regenerative capacity of the brain is insufficient. Neonatal encephalopathy leads to high mortality rates and long-term neurologic deficits in babies worldwide. Therefore, there is an urgent need to develop more efficient therapeutic strategies. The latest findings indicate that stem cells represent a novel therapeutic possibility to improve outcome in models of neonatal encephalopathy. Transplanted stem cells secrete factors that stimulate and maintain neurogenesis, thereby increasing cell proliferation, neuronal differentiation, and functional integration. Understanding the molecular and cellular mechanisms underlying neurogenesis after an insult is crucial for developing tools to enhance the neurogenic capacity of the brain. The aim of this review is to discuss the endogenous capacity of the neonatal brain to regenerate after a cerebral ischemic insult. We present an overview of the molecular and cellular mechanisms underlying endogenous regenerative processes during development as well as after a cerebral ischemic insult. Furthermore, we will consider the potential to use stem cell transplantation as a means to boost endogenous neurogenesis and restore brain function.

Neonatal dexamethasone treatment exacerbates hypoxic-ischemic brain injury

Background

The synthetic glucocorticoid dexamethasone (DEX) is commonly used to prevent chronic lung disease in prematurely born infants. Treatment regimens usually consist of high doses of DEX for several weeks, notably during a critical period of brain development. Therefore, there is some concern about adverse effects of this clinical practice on fetal brain development. In this study, using a clinically relevant rat model, we examined the impact of neonatal DEX treatment on subsequent brain injury due to an episode of cerebral hypoxia-ischemia (HI).

Results

We found that a 3-day tapering course (0.5, 0.3 and 0.1 mg/kg) of DEX treatment in rat pups on postnatal days 1–3 (P1-3) exacerbated HI-induced brain injury on P7 by a glucocorticoid receptor-mediated mechanism. The aggravating effect of neonatal DEX treatment on HI-induced brain injury was correlated with decreased glutamate transporter-1 (GLT-1)-mediated glutamate reuptake. The expression levels of mRNA and protein of GLT-1 were significantly reduced by neonatal DEX treatment. We also found that the administration of β-lactam antibiotic ceftriaxone increased GLT-1 protein expression and significantly reduced HI-induced brain injury in neonatal DEX-treated rats.

Conclusions

These results suggest that early DEX exposure may lead the neonatal brain to be more vulnerable to subsequent HI injury, which can be ameliorated by administrating ceftriaxone.

Enhanced NMDA receptor tyrosine phosphorylation and increased brain injury following neonatal hypoxia-ischemia in mice with neuronal Fyn overexpression

The Src family kinases (SFKs) Src and Fyn are implicated in hypoxic-ischemic (HI) injury in the developing brain. However, it is unclear how these particular SFKs contribute to brain injury. Using neuron-specific Fyn overexpressing (OE) mice, we investigated the role of neuronal Fyn in neonatal brain HI. Wild type (WT) and Fyn OE mice were subjected to HI using the Vannucci model at postnatal day 7. Brains were scored five days later for evaluation of damage using cresyl violet and iron staining. Western blotting with postsynaptic density (PSD)-associated synaptic membrane proteins and co-immunoprecipitation with cortical lysates were performed at various time points after HI to determine NMDA receptor tyrosine phosphorylation and Fyn kinase activity. Fyn OE mice had significantly higher mortality and brain injury compared to their WT littermates. Neuronal Fyn overexpression led to sustained NR2A and NR2B tyrosine phosphorylation and enhanced NR2B phosphorylation at tyrosine (Y) 1472 and Y1252 in synaptic membranes. These early changes correlated with higher calpain activity 24h after HI in Fyn OE mice relative to WT animals. Our findings suggest a role for Fyn kinase in neuronal death after neonatal HI, possibly via up-regulation of NMDA receptor tyrosine phosphorylation.

Pathophysiology of cerebral palsy

Cerebral palsy (CP), defined as a group of nonprogressive disorders of movement and posture, is the most common cause of severe neurodisability in children. Understanding its physiopathology is crucial to developing some protective strategies. Interruption of oxygen supply to the fetus or brain asphyxia was classically considered to be the main causal factor explaining later CP. However several ante-, peri-, and postnatal factors could be involved in the origins of CP syndromes. Congenital malformations are rarely identified. CP is most often the result of environmental factors, which might interact with genetic vulnerabilities, and could be severe enough to cause the destructive injuries visible with standard imaging (i.e., ultrasonographic study or MRI), predominantly in the white matter in preterm infants and in the gray matter and the brainstem nuclei in full-term newborns. Moreover they act on an immature brain and could alter the remarkable series of developmental events. Biochemical key factors originating in cell death or cell process loss, observed in hypoxic-ischemic as well as inflammatory conditions, are excessive production of proinflammatory cytokines, oxidative stress, maternal growth factor deprivation, extracellular matrix modifications, and excessive release of glutamate, triggering the excitotoxic cascade. Only two strategies have succeeded in decreasing CP in 2-year-old children: hypothermia in full-term newborns with moderate neonatal encephalopathy and administration of magnesium sulfate to mothers in preterm labor.

Bench to cribside: the path for developing a neuroprotectant

The consequences of perinatal brain injury include immeasurable anguish for families and substantial ongoing costs for care and support of effected children. Factors associated with perinatal brain injury in the preterm infant include inflammation and infection, and with increasing gestational age, a higher proportion is related to hypoxic-ischemic events, such as stroke and placental abruption. Over the past decade, we have acquired new insights in the mechanisms underpinning injury and many new tools to monitor outcome in perinatal brain injury in our experimental models. By embracing these new technologies, we can expedite the screening of novel therapies. This is critical as despite enormous efforts of the research community, hypothermia is the only viable neurotherapeutic, and this procedure is limited to term birth and postcardiac arrest hypoxic-ischemic events. Importantly, experimental and preliminary data in humans also indicate a considerable therapeutic potential for melatonin against perinatal brain injury. However, even if this suggested potential is proven, the complexity of the human condition means we are likely to need additional neuroprotective and regenerative strategies. Thus, within this review, we will outline what we consider the key stages of preclinical testing and development for a neuroprotectant or regenerative neurotherapy for perinatal brain injury. We will also highlight examples of novel small animal physiological and behavioral testing that gives small animal preclinical models greater clinical relevance. We hope these new tools and an integrated bench to cribside strategic plan will facilitate the fulfillment of our overarching goal, improving the long-term brain health and quality of life for infants suffering perinatal brain injury.

Endocannabinoids reduce cerebral damage after hypoxic-ischemic injury in perinatal rats

Hypoxic-ischemic (HI) insult during the perinatal period remains as one of the most common causes of brain injury and produces long-term neurological deficits, and there is a growing need for effective therapies. The aim of the present work was to perform a prospective study designed to assess the possible protector effect of two endocannabinoids: 2-arachidonoylglycerol (2AG) and anandamide (AEA) in the brain after HI injury in perinatal rat model. We evaluate their effects on cell death and check several cellular parameters. 7-days-old Wistar rats were assigned to four different experimental groups (n=7-10): Sham, HI, and HI treated with 2AG or AEA. The injury was induced by the left carotid artery ligature and subsequent exposure to 8% O(2) for 120 min. Immediately after the injury, treated groups received a single dose of 2AG (1mg/kg) or AEA (5mg/kg) and then animals were sacrificed 24, 72 h or 7 days after the HI event. Brains fixed by perfusion were stained with Nissl for morphological studies, and non-fixed brains were dissociated and analyzed by flow cytometry to quantify apoptosis, mitochondrial state, intracellular calcium and reactive oxygen species. Our results show that both 2AG and AEA have beneficial effects after HI injury in this rat model, producing a remarkable amelioration of brain injury, reducing apoptotic cell death, contributing to the maintenance of mitochondrial functionality, and improving cellular parameters such as the influx of calcium and ROS production.

Fetal stress and programming of hypoxic/ischemic-sensitive phenotype in the neonatal brain: mechanisms and possible interventions

Growing evidence of epidemiological, clinical and experimental studies has clearly shown a close link between adverse in utero environment and the increased risk of neurological, psychological and psychiatric disorders in later life. Fetal stresses, such as hypoxia, malnutrition, and fetal exposure to nicotine, alcohol, cocaine and glucocorticoids may directly or indirectly act at cellular and molecular levels to alter the brain development and result in programming of heightened brain vulnerability to hypoxic-ischemic encephalopathy and the development of neurological diseases in the postnatal life. The underlying mechanisms are not well understood. However, glucocorticoids may play a crucial role in epigenetic programming of neurological disorders of fetal origins. This review summarizes the recent studies about the effects of fetal stress on the abnormal brain development, focusing on the cellular, molecular and epigenetic mechanisms and highlighting the central effects of glucocorticoids on programming of hypoxic-ischemic-sensitive phenotype in the neonatal brain, which may enhance the understanding of brain pathophysiology resulting from fetal stress and help explore potential targets of timely diagnosis, prevention and intervention in neonatal hypoxic-ischemic encephalopathy and other brain disorders.

Effect of hypoxia on expression of selected proteins involved in regulation of apoptotic activity in striatum of newborn piglets

The levels of selected neuroregulatory proteins that inhibit or promote apoptotic cell death were measured in the striatum of piglets subjected to precisely controlled 1 h hypoxic insult followed by 0, 2 and 4 h recovery and compared to sham operated animals. The anti-apoptotic proteins: there were increases in Survivin at 0 (157%, P = 0.031) and 4 h (171%, P = 0.033), in Bcl-XL at 0 (138%, P = 0.028) and 4 h (143%, P = 0.007), in VEGF at 4 h (185%, P = 0.019) and Hsp27 at 2 h (144%, P = 0.05) and 4 h (143%, P = 0.05). The pro-apoptotic proteins: caspases-1 and 7 increased at 4 h (135%, P = 0.05) and (129%, P = 0.038), respectively. Bim increased after 4 h (115%, P = 0.028), Apoptosis Inducing Factor after 2 h (127%, P = 0.048) and Calpain after 4 h (143% of control, P = 0.04). Hypoxia causes increase in levels of both anti- and pro-apoptotic proteins. Their relative activity determines the outcome in terms of cell damage and neuronal deficit.

Neuroprotective multifunctional iron chelators: from redox-sensitive process to novel therapeutic opportunities

Accumulating evidence suggests that many cytotoxic signals occurring in the neurodegenerative brain can initiate neuronal death processes, including oxidative stress, inflammation, and accumulation of iron at the sites of the neuronal deterioration. Neuroprotection by iron chelators has been widely recognized with respect to their ability to prevent hydroxyl radical formation in the Fenton reaction by sequestering redox-active iron. An additional neuroprotective mechanism of iron chelators is associated with their ability to upregulate or stabilize the transcriptional activator, hypoxia-inducible factor-1alpha (HIF-1alpha). HIF-1alpha stability within the cells is under the control of a class of iron-dependent and oxygen-sensor enzymes, HIF prolyl-4-hydroxylases (PHDs) that target HIF-1alpha for degradation. Thus, an emerging novel target for neuroprotection is associated with the HIF system to promote stabilization of HIF-1alpha and increase transcription of HIF-1-related survival genes, which have been reported to be regulated in patient's brains afflicted with diverse neurodegenerative diseases. In accordance, a new potential therapeutic strategy for neurodegenerative diseases is explored, by which iron chelators would inhibit PHDs, target the HIF-1-signaling pathway and ultimately activate HIF-1-dependent neuroprotective genes. This review discusses two interrelated approaches concerning therapy targets in neurodegeneration, sharing in common the implementation of iron chelation activity: antioxidation and HIF-1-pathway activation.

Inhibition of the JNK/AP-1 pathway reduces neuronal death and improves behavioral outcome after neonatal hypoxic-ischemic brain injury

Perinatal hypoxic-ischemic (HI) brain damage continues to be a major clinical problem. We investigated the contribution of the MAP kinase c-Jun N-terminal kinase (JNK), to neonatal HI brain damage. JNK regulates several transcriptional (via AP-1 activation) and non-transcriptional processes involved in brain damage such as inflammation and cell death/survival. P7 rats were subjected to HI by unilateral carotid artery occlusion and hypoxia. HI-induced activation of cerebral AP-1 peaked at 3-6h post-HI. Intraperitoneal administration of the JNK-inhibitor TAT-JBD immediately after HI prevented AP-1 activation. TAT-JBD treatment within 3h after HI reduced early neuronal damage by approximately 30%. JNK/AP-1 inhibition did not reduce HI-induced cytokine/chemokine expression. Analysis of indicators of apoptotic cell death revealed that TAT-JBD markedly reduced the HI-induced increase in active caspase 3. However, the upstream mediators of apoptosis: active caspase 8, cleaved Bid, mitochondrial cytochrome c release and caspase 9 cleavage were not reduced after TAT-JBD. TAT-JBD inhibited the HI-induced increase in Smac/DIABLO, an inhibitor of IAPs that prevent activation of caspase 3. TAT-JBD treatment also reduced cleavage of alpha-fodrin, indicating that calpain-mediated brain damage was reduced. Neuroprotection by TAT-JBD treatment was long-lasting as gray- and white matter damage was diminished by approximately 50% at 14 weeks post-HI concomitantly with marked improvement of sensorimotor behavior and cognitive functioning. In conclusion, JNK inhibition by TAT-JBD treatment reduced neonatal HI brain damage with a therapeutic window of 3h and long-lasting anatomical and behavioral improvements. We propose that inhibition of mitochondrial Smac/DIABLO release and calpain activation contribute to neuroprotection by TAT-JBD.

Normobaric hyperoximia increases hypoxia-induced cerebral injury: DTI study in rats

Perinatal hypoxia affects normal neurological development and can lead to motor, behavioral and cognitive deficits. A common acute treatment for perinatal hypoxia is oxygen resuscitation (hyperoximia), a controversial treatment. Magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI), was performed in a P7 rat model of perinatal hypoxia to determine the effect of hyperoximia. These studies were performed on two groups of animals: 1) animals which were subjected to ischemia followed by hypoxia (HI), and 2) HI followed by hyperoximic treatment (HHI). Lesion volumes on high resolution MRI and DTI derived measures, fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivities (lambda(l) and lambda(t), respectively) were measured in vivo one day, one week, and three weeks after injury. Most significant differences in the MRI and DTI measures were found at three weeks after injury. Specifically, three weeks after HHI injury resulted in significantly larger hyperintense lesion volumes (95.26 +/- 50.42 mm(3)) compared to HI (22.25 +/- 17.62 mm(3)). The radial diffusivity lambda(t) of the genu of corpus callosum was significantly larger in HHI (681 +/- 330 x 10(-6) mm(2)/sec) than in HI (486 +/- 96 x 10(-6) mm(2)/sec). Over all, most significant differences in all the DTI metrics (FA, MD, lambda(t), lambda(l)) at all time points were found in the corpus callosum. Our results suggest that treatment of perinatal hypoxia with normobaric oxygen does not ameliorate, but exacerbates damage.

Free iron, total F-isoprostanes and total F-neuroprostanes in a model of neonatal hypoxic-ischemic encephalopathy: neuroprotective effect of melatonin

Oxidative stress due to free radical formation and initiation of abnormal oxidative reactions is involved in several diseases of newborns, such as hypoxic-ischemic encephalopathy. Melatonin, an endogenously produced indoleamine primarily formed in the pineal gland, is a potent free radical scavenger as well as an indirect antioxidant. The present study was conducted to evaluate the formation of oxidative damage mediators and the possible effect of melatonin treatment in a model of hypoxic-ischemic encephalopathy in 7-day-old rats. Pups were subjected to permanent ligation of the right common carotid artery and exposed for 2.5 hr to a nitrogen-oxygen mixture (92% and 8%, respectively) (hypoxia-ischemia, HI). Melatonin was injected intraperitoneally to a group of rats at the dose of 15 mg/kg 30 min before starting the ischemic procedure (HI-Melatonin). After 24 hr of treatment, in homogenized cerebral cortex, desferoxamine (DFO)-chelatable free iron, total F(2)-isoprostanes and total F(4)-neuroprostanes, originating from the free radical-catalyzed peroxidation of arachidonic and docosahexaenoic acids, respectively, were determined. HI induced a significant increase in DFO-chelatable iron, total F(2)-isoprostanes and F(4)-neuroprostanes in both right and left side of the cerebral cortex. In HI-Melatonin-treated animals the levels of free iron, F(2)-isoprostanes, and F(4)-neuroprostanes were significantly lower than that in HI rats and the values were similar to controls. These data show the important neuroprotective role of melatonin in reducing oxidative damage resulting from HI. Melatonin could represent a potential safe approach to perinatal brain damage in humans.

Effect of hyperoxia on serine phosphorylation of apoptotic proteins in mitochondrial membranes of the cerebral cortex of newborn piglets

Previous studies have shown that hyperoxia results in cerebral cortical neuronal apoptosis. Studies have also shown that phosphorylation of anti-apoptotic proteins Bcl-2 and Bcl-xl results in loss of their anti-apoptotic potential leading to alteration in mitochondrial membrane permeability and the release of apoptogenic proteins in the neuronal cell of the newborn piglets. The present study tests the hypothesis that cerebral hyperoxia will result in increased serine phosphorylation of apoptotic proteins Bcl-2, Bcl-xl, Bax, and Bad in the mitochondrial membranes of the cerebral cortex of newborn piglets. Twelve newborn piglets were divided into normoxic (Nx, n = 6) exposed to an FiO(2) of 0.21 for 1 h and hyperoxic (Hyx, n = 6) exposed to FiO(2) of 1.0 for 1 h. In the Hyx group, PaO(2) was maintained above 400 mmHg while the Nx group was kept at 80-100 mmHg. Cerebral cortical tissue was harvested and mitochondrial fractions were isolated. Mitochondrial membrane proteins were separated using 12% SDS-PAGE, and probed with anti-serine phosphorylated Bcl-2, Bcl-xl, Bax, and Bad antibodies. Protein bands were detected, analyzed by imaging densitometry and density expressed as absorbance (OD x mm(2)). Phosphorylated Bcl-2 (p-Bcl-2) protein density (OD x mm(2)) was 81.81 +/- 9.24 in Nx and 158.34 +/- 10.66 in Hyx (P < 0.05). Phosphorylated Bcl-xl (p-Bcl-xl) protein density was 52.98 +/- 3.59 in Nx and 99.62 +/- 18.22 in Hyx (P < 0.05). Phosphorylated Bax (p-Bax) protein was 161.13 +/- 6.27 in Nx and 174.21 +/- 15.95 in Hyx (P = NS). Phosphorylated Bad (p-Bad) protein was 166.24 +/- 9.47 in Nx 155.38 +/- 12.32 in Hyx (P = NS). The data show that there is a significant increase in serine phosphorylation of Bcl-2 and Bcl-xl proteins while phosphorylation of Bad and Bax proteins were not altered during hyperoxia in the mitochondrial fraction of the cerebral cortex of newborn piglets. We conclude that hyperoxia results in differential post-translational modification of anti-apoptotic proteins Bcl-2 and Bcl-xl as compared to pro-apoptotic proteins Bax and Bad in mitochondria. We speculate that phosphorylation of Bcl-2 and Bcl-xl will result in loss of their anti-apoptotic potential by preventing their dimerization with Bax leading to activation of the caspase cascade of neuronal death.