Minocycline-induced attenuation of iron overload and brain injury after experimental germinal matrix hemorrhage

The Role of Oxidative Stress in the Progression of Secondary Brain Injury Following Germinal Matrix Hemorrhage

Germinal matrix hemorrhage (GMH) can be a fatal condition responsible for the death of 1.7% of all neonates in the USA. The majority of GMH survivors develop long-term sequalae with debilitating comorbidities. Higher grade GMH is associated with higher mortality rates and higher prevalence of comorbidities. The pathophysiology of GMH can be broken down into two main titles: faulty hemodynamic autoregulation and structural weakness at the level of tissues and cells. Prematurity is the most significant risk factor for GMH, and it predisposes to both major pathophysiological mechanisms of the condition. Secondary brain injury is an important determinant of survival and comorbidities following GMH. Mechanisms of brain injury secondary to GMH include apoptosis, necrosis, neuroinflammation, and oxidative stress. This review will have a special focus on the mechanisms of oxidative stress following GMH, including but not limited to inflammation, mitochondrial reactive oxygen species, glutamate toxicity, and hemoglobin metabolic products. In addition, this review will explore treatment options of GMH, especially targeted therapy.

Application of LRG mechanism in normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a prevalent type of hydrocephalus, including secondary normal pressure hydrocephalus (SNPH) and idiopathic normal pressure hydrocephalus (INPH). However, its clinical diagnosis and pathological mechanism are still unclear. Leucine-rich α-2 glycoprotein (LRG) is involved in various human diseases, including cancer, diabetes, cardiovascular disease, and nervous system diseases. Now the physiological mechanism of LRG is still being explored. According to the current research results on LRG, we found that the agency of LRG has much to do with the known pathological process of NPH. This review focuses on analyzing the LRG signaling pathways and the pathological mechanism of NPH. According to the collected literature evidence, we speculated that LRG probably be involved in the pathological process of NPH. Finally, based on the mechanism of LRG and NPH, we also summarized the evidence of molecular targeted therapies for future research and clinical application.

Iron homeostasis and post-hemorrhagic hydrocephalus: a review

Iron physiology is regulated by a complex interplay of extracellular transport systems, coordinated transcriptional responses, and iron efflux mechanisms. Dysregulation of iron metabolism can result in defects in myelination, neurotransmitter synthesis, and neuronal maturation. In neonates, germinal matrix-intraventricular hemorrhage (GMH-IVH) causes iron overload as a result of blood breakdown in the ventricles and brain parenchyma which can lead to post-hemorrhagic hydrocephalus (PHH). However, the precise mechanisms by which GMH-IVH results in PHH remain elusive. Understanding the molecular determinants of iron homeostasis in the developing brain may lead to improved therapies. This manuscript reviews the various roles iron has in brain development, characterizes our understanding of iron transport in the developing brain, and describes potential mechanisms by which iron overload may cause PHH and brain injury. We also review novel preclinical treatments for IVH that specifically target iron. Understanding iron handling within the brain and central nervous system may provide a basis for preventative, targeted treatments for iron-mediated pathogenesis of GMH-IVH and PHH.

Minocycline attenuates hydrocephalus and inhibits iron accumulation, ependymal damage and epiplexus cell activation after intraventricular hemorrhage in aged rats

Intracerebral hemorrhage is primarily a disease of the elderly and it is frequently accompanied by intraventricular hemorrhage (IVH) which can lead to posthemorrhagic hydrocephalus and poor prognosis. Red blood cell iron has been implicated in brain injury after cerebral hemorrhage. The current study examined using T2* magnetic resonance imaging (MRI) to detect periventricular iron deposition after IVH and investigated the effects of minocycline on hydrocephalus in an aged rat IVH model. It had three parts. In part 1, male aged rats received a 200 μl injection of saline or autologous blood into the lateral ventricle and were euthanized at day 14. In parts 2 and 3, aged IVH rats were treated with vehicle or minocycline and euthanized at day 7 or 14. Rats underwent MRI to quantify hydrocephalus and iron deposition followed by brain histology and immunohistochemistry. Periventricular iron overload was found after IVH using T2* MRI and confirmed by histology. IVH also caused ventricular wall damage and increased the number of CD68(+) choroid plexus epiplexus cells. Minocycline administration reduced iron deposition and ventricular volume at days 7 and 14 after IVH, as well as ventricle wall damage and epiplexus cell activation. In summary, IVH-induced hydrocephalus is associated with periventricular iron deposition, ependymal damage and choroid plexus epiplexus cell activation in aged rats. Minocycline attenuated those effects and might be a potential treatment for posthemorrhagic hydrocephalus in the elderly.

Minocycline Protects PC12 Cells Against Cadmium-Induced Neurotoxicity by Modulating Apoptosis

Cadmium (Cd) is a well-known heavy metal and a neurotoxic agent. Minocycline (Mino) is an anti-microbial agent with a lipophilic structure that crosses the blood-brain barrier and enters the cerebral tissue. In recent studies, Mino has been introduced as an antioxidant and anti-apoptotic chemical compound, and therefore, it was examined as a protective candidate against Cd-induced neurotoxicity. In this study, PC12 cells were exposed to Cd alone, or after being pre-treated with Mino. Initially, the cell viability and oxidative stress were analyzed using the MTT assay and fluorimetry, respectively. Then, Cd-induced apoptosis and Mino anti-apoptotic effect were evaluated in both intrinsic and extrinsic pathways using western blot analysis. Exposing PC12 cells to Cd for 24 h decreased cell viability and increased production of reactive oxygen species in comparison with the control group. Cd (35 μM) also elevated the level of caspase-8, Bax/Bcl-2, and caspase-3 proteins in the cells. Mino pre-treatment for 2 h (100 nM) increased the number of viable cells and decreased the production of reactive oxygen species, and the level of all apoptotic markers in comparison to Cd-treated cells. Considering all the evidence, it appears that Mino holds promising antioxidant and anti-apoptotic activity and can protect cells against Cd-induced oxidative stress and prevent apoptotic cell death.

The Regulated Cell Death and Potential Interventions in Preterm Infants after Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) in preterm infants is one of the major co-morbidities of preterm birth and is associated with long-term neurodevelopmental deficits. There are currently no widely accepted treatments to prevent ICH or therapies for the neurological sequelae. With studies broadening the scope of cell death, the newly defined concept of regulated cell death has enriched our understanding of the underlying mechanisms of secondary brain injury after ICH and has suggested potential interventions in preterm infants. In this review, we will summarize the current evidence for regulated cell death pathways in preterm infants after ICH, including apoptosis, necroptosis, pyroptosis, ferroptosis, autophagy, and PANoptosis as well as several potential intervention strategies that may protect the immature brain from secondary injury after ICH through regulating regulated cell death.

Novel therapeutic modulators of astrocytes for hydrocephalus

Hydrocephalus is mainly characterized by excessive production or impaired absorption of cerebrospinal fluid that causes ventricular dilation and intracranial hypertension. Astrocytes are the key response cells to inflammation in the central nervous system. In hydrocephalus, astrocytes are activated and show dual characteristics depending on the period of development of the disease. They can suppress the disease in the early stage and may aggravate it in the late stage. More evidence suggests that therapeutics targeting astrocytes may be promising for hydrocephalus. In this review, based on previous studies, we summarize different forms of hydrocephalus-induced astrocyte reactivity and the corresponding function of these responses in hydrocephalus. We also discuss the therapeutic effects of astrocyte regulation on hydrocephalus in experimental studies.

Memantine associated with ventricular-subcutaneous shunt promotes behavioral improvement, reduces reactive astrogliosis and cell death in juvenile hydrocephalic rats

Hydrocephalus is defined as the accumulation of cerebrospinal fluid in the brain ventricles. The usual treatment of hydrocephalus is surgical (shunt), but not all patients can undergo treatment immediately after diagnosis. Thus, neuroprotective measures were tested to minimize the tissue damage involved. Memantine is a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, which has shown a neuroprotective action in neurodegenerative diseases. This study aimed to evaluate the neuroprotective response of memantine in animals treated with or without a ventricular-subcutaneous shunt. Seven-day-old male Wistar rats induced by intracisternal injection of kaolin were used, divided into five groups: intact control (n=10), hydrocephalic (n=10), hydrocephalic treated with memantine (20mg/kg/day) (n=10), hydrocephalic treated with shunt (n=10), hydrocephalic treated with shunt and memantine (20mg/kg/day) (n=10). Memantine administration was started on the day after hydrocephalus induction and continued until the last day of the experimental period, totaling 21 consecutive days of drug application. The CSF shunt surgery was performed seven days after hydrocephalus induction. Behavioral tests (open field, and modified Morris water maze), histological, and immunohistochemical evaluations were performed. Treatment with memantine resulted in significant improvement (p<0.05) in sensorimotor development, preservation of spatial memory, reduction of astrocytic reaction in the corpus callosum, cortex, and germinal matrix. When associated with the shunt, it has also been shown to reduce the cell death cascade. It is concluded that memantine is a promising adjuvant drug with beneficial potential for the treatment of lesions secondary to hydrocephalus.

Cerebral gray matter injuries in infants with intraventricular hemorrhage

While intraventricular hemorrhage (IVH) predominantly damages the periventricular white matter, it induces substantial injury to the cerebral gray matter. IVH destroys the germinal matrix, suppresses neurogenesis, and disrupts corticogenesis, thereby reducing the number of neurons in the upper cortical layer and volume of the cerebral gray matter. The pathogenesis of gray matter injury is attributed to IVH-induced oxidative stress, inflammation, and mass effect damaging the germinal matrix as well as to post-hemorrhagic ventricular dilation (PHVD). The IVH-induced cerebral gray matter injury and PHVD contribute to cognitive deficits and neurobehavioral disorders. Neuroimaging has enhanced our understanding of cerebral gray matter injury and is a valuable predictor of neurodevelopmental outcomes. Evidence from therapies tested in preclinical models and clinical trials suggests that strategies to promote neurogenesis, reduce cerebral inflammation and oxidative stress, and remove blood clots from the ventricles might enhance the outcome of these infants. This review offers an integrated view of new insights into the mechanisms underlying gray matter injury in premature infants with IVH and highlights the imminent therapies to restore neurodevelopmental dysfunction in IVH survivors.

Post-hemorrhagic ventricular dilatation affects white matter maturation in extremely preterm infants

BACKGROUND

Data on microstructural white matter integrity in preterm infants with post-hemorrhagic ventricular dilatation (PHVD) using diffusion tensor imaging (DTI) are limited. Also, to date, no study has focused on the DTI changes in extremely preterm (EP) infants with PHVD.

METHODS

A case-control study of EP infants <28 weeks' gestation with PHVD was conducted. Diffusivity and fractional anisotropy (FA) values of corticospinal tracts (CST) and corpus callosum (CC) were measured using DTI at term-equivalent age. Outcomes were assessed at 2-years-corrected age.

RESULTS

Twenty-one infants with PHVD and 21 matched-controls were assessed. FA values in the CC were lower in infants with PHVD compared with controls (mean difference, 0.05 [95% confidence interval (CI), 0.02-0.08], p < 0.001). In infants with periventricular hemorrhagic infarction, FA values in the CC were lower than in controls (mean difference, 0.05 [95% CI, 0.02-0.09], p = 0.005). The composite cognitive and motor scores were associated with the FA value of the CC (coefficient 114, p = 0.01 and coefficient 147, p = 0.004; respectively).

CONCLUSIONS

Extremely preterm infants with PHVD showed lower FA values in CC. A positive correlation was also shown between the composite cognitive and motor scores and FA value of the CC at 2-years-corrected age.

IMPACT

Extremely preterm infants with post-hemorrhagic ventricular dilatation showed lower fractional anisotropy values in their corpus callosum compared with controls reflecting the impaired microstructure of these commissural nerve fibers that are adjacent to the dilated ventricles. Impaired microstructure of the corpus callosum was shown to be associated with cognitive and motor scores at 2-years-corrected age.

Ultrasound imaging of preterm brain injury: fundamentals and updates

Neurosonography has become an essential tool for diagnosis and serial monitoring of preterm brain injury. Preterm infants are at significantly higher risk of hypoxic-ischemic injury, intraventricular hemorrhage, periventricular leukomalacia and post-hemorrhagic hydrocephalus. Neonatologists have become increasingly dependent on neurosonography to initiate medical and surgical interventions because it can be used at the bedside. While brain MRI is regarded as the gold standard for detecting preterm brain injury, neurosonography offers distinct advantages such as its cost-effectiveness, diagnostic utility and convenience. Neurosonographic signatures associated with poor long-term outcomes shape decisions regarding supportive care, medical or behavioral interventions, and family members' expectations. Within the last decade substantial progress has been made in neurosonography techniques, prompting an updated review of the topic. In addition to the up-to-date summary of neurosonography, this review discusses the potential roles of emerging neurosonography techniques that offer new functional insights into the brain, such as superb microvessel imaging, elastography, three-dimensional ventricular volume assessment, and contrast-enhanced US.

Mechanisms of neuroinflammation in hydrocephalus after intraventricular hemorrhage: a review

Intraventricular hemorrhage (IVH) is a significant cause of morbidity and mortality in both neonatal and adult populations. IVH not only causes immediate damage to surrounding structures by way of mass effect and elevated intracranial pressure; the subsequent inflammation causes additional brain injury and edema. Of those neonates who experience severe IVH, 25-30% will go on to develop post-hemorrhagic hydrocephalus (PHH). PHH places neonates and adults at risk for white matter injury, seizures, and death. Unfortunately, the molecular determinants of PHH are not well understood. Within the past decade an emphasis has been placed on neuroinflammation in IVH and PHH. More information has come to light regarding inflammation-induced fibrosis and cerebrospinal fluid hypersecretion in response to IVH. The aim of this review is to discuss the role of neuroinflammation involving clot-derived neuroinflammatory factors including hemoglobin/iron, peroxiredoxin-2 and thrombin, as well as macrophages/microglia, cytokines and complement in the development of PHH. Understanding the mechanisms of neuroinflammation after IVH may highlight potential novel therapeutic targets for PHH.

Delayed Minocycline Treatment Ameliorates Hydrocephalus Development and Choroid Plexus Inflammation in Spontaneously Hypertensive Rats

Hydrocephalus is a complicated disorder that affects both adult and pediatric populations. The mechanism of hydrocephalus development, especially when there is no mass lesion present causing an obstructive, is poorly understood. Prior studies have demonstrated that spontaneously hypertensive rats (SHRs) develop hydrocephalus by week 7, which was attenuated with minocycline. The aim of this study was to determine sex differences in hydrocephalus development and to examine the effect of minocycline administration after hydrocephalus onset. Male and female Wistar-Kyoto rats (WKYs) and SHRs underwent magnetic resonance imaging at weeks 7 and 9 to determine ventricular volume. Choroid plexus epiplexus cell activation, cognitive deficits, white matter atrophy, and hippocampal neuronal loss were examined at week 9. In the second phase of the experiment, male SHRs (7 weeks old) were treated with either saline or minocycline (20 mg/kg) for 14 days, and similar radiologic, histologic, and behavior tests were performed. Hydrocephalus was present at week 7 and increased at week 9 in both male and female SHRs, which was associated with greater epiplexus cell activation than WKYs. Male SHRs had greater ventricular volume and epiplexus cell activation compared to female SHRs. Minocycline administration improved cognitive function, white matter atrophy, and hippocampal neuronal cell loss. In conclusion, while both male and female SHRs developed hydrocephalus and epiplexus cell activation by week 9, it was more severe in males. Delayed minocycline treatment alleviated hydrocephalus, epiplexus macrophage activation, brain pathology, and cognitive impairment in male SHRs.

Recovery of the brain after intraventricular hemorrhage

Intraventricular hemorrhage (IVH) remains a major complication of prematurity, worldwide. The severity of IVH is variable, ranging from a tiny germinal matrix bleed to a moderate-to-large ventricular hemorrhage or periventricular hemorrhagic infarction. Survivors with IVH often suffer from hydrocephalus and white matter injury. There is no tangible treatment to prevent post-hemorrhagic cerebral palsy, cognitive deficits, or hydrocephalus in these infants. White matter injury is attributed to blood-induced damage to axons and maturing oligodendrocyte precursors, resulting in reduced myelination and axonal loss. Hydrocephalus results from obstructed CSF circulation by blood clots, increased CSF production, and reduced CSF absorption by lymphatics and arachnoid villi. Several strategies to promote neurological recovery have shown promise in animal models, including the elimination of blood and blood products, alleviating cerebral inflammation and oxidative stress, as well as promoting survival and maturation of oligodendrocyte precursors. The present review integrates novel mechanisms of brain injury in IVH and the imminent therapies to alleviate post-hemorrhagic white matter injury and hydrocephalus in the survivors with IVH.

Neuroprotection of chromobox 7 knockout in the mouse after cerebral ischemia-reperfusion injury via nuclear factor E2-related factor 2/hemeoxygenase-1 signaling pathway

OBJECTIVE

To explore the mechanism of chromobox 7 (CBX7)-mediated nuclear factor E2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) signaling pathway in the cerebral ischemia/reperfusion (I/R) injury.

METHODS

The experimental wild-type (WT) and CBX7^-/- mice were used to establish cerebral I/R models using the middle cerebral artery occlusion (MCAO) surgery to determine CBX7 levels at different time points after MCAO injury. For all mice, neurological behavior, infarct size, water content, and oxidative stress-related indicators were determined, and transferase (TdT)-mediated dUTP-biotin nick-end labeling (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL)) staining method was employed to observe cell apoptosis, while Western blot to measure the expression of CBX7 and Nrf/HO-1 pathway-related proteins.

RESULTS

At 6 h, 12 h, 24 h, 3 days, and 7 days after mice with MCAO, CBX7 expression was gradually up-regulated and the peak level was reached at 24 h. Mice in the WT + MCAO group had increased infarct size, with significant increases in the modified neurological severity scores and water content in the brain, as well as the quantity of TUNEL-positive cells. For the oxidative stress-indicators, an increase was seen in the content of MDA (malondial dehyde), but the activity of SOD (superoxide dismutase) and content of GSH-PX (glutathione peroxidase) and CAT (catalase) were decreased; meanwhile, the protein expression of CBX7, HO-1, and nuclear Nrf2 was up-regulated, while the cytoplasmic Nrf2 was down-regulated. Moreover, CBX7 knockout attenuated I/R injury in mice.

CONCLUSION

Knockout of CBX7 may protect mice from cerebral I/R injury by reducing cell apoptosis and oxidative stress, possibly via activating the Nrf2/HO-1 pathway.

The association of Edaravone with shunt surgery improves behavioral performance, reduces astrocyte reaction and apoptosis, and promotes neuroprotection in young hydrocephalic rats

The neuroprotective effect of Edaravone in young hydrocephalic rats associated with a CSF derivation system was evaluated. The drug has already been shown to be beneficial in experimental hydrocephalus, but the combination of this drug with shunt surgery has not yet been investigated. Fifty-seven-day-old Wistar rats submitted to hydrocephalus by injection of kaolin in the cisterna magna were used and divided into five groups: control (n = 10), hydrocephalic (n = 10), hydrocephalic treated with Edaravone (20 mg/kg/day) (n = 10), hydrocephalic treated with shunt (n = 10) and hydrocephalic treated with shunt and Edaravone (n = 10). Administration of the Edaravone was started 24 h after hydrocephalus induction (P1) and continued until the experimental endpoint (P21). The CSF shunt surgery was performed seven days after hydrocephalus induction (P7). Open-field tests, histological evaluation by hematoxylin and eosin, immunohistochemistry by Caspase-3 and GFAP, and ELISA biochemistry by GFAP were performed. Edaravone reduced reactive astrogliosis in the corpus callosum and germinal matrix (p < 0.05). When used alone or associated with CSF shunt surgery, the drug decreased the cell death process (p < 0.0001) and improved the morphological aspect of the astroglia (p < 0.05). The results showed that Edaravone associated with CSF bypass surgery promotes neuroprotection in young hydrocephalic rats by reducing reactive astrogliosis and decreasing cell death.

Neuroprotection of chromobox 7 knockout in the mouse after cerebral ischemia-reperfusion injury via nuclear factor E2-related factor 2/hemeoxygenase-1 signaling pathway

OBJECTIVE

To explore the mechanism of chromobox 7 (CBX7)-mediated nuclear factor E2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) signaling pathway in the cerebral ischemia/reperfusion (I/R) injury.

METHODS

The experimental wild-type (WT) and CBX7^-/- mice were used to establish cerebral I/R models using the middle cerebral artery occlusion (MCAO) surgery to determine CBX7 levels at different time points after MCAO injury. For all mice, neurological behavior, infarct size, water content, and oxidative stress-related indicators were determined, and transferase (TdT)-mediated dUTP-biotin nick-end labeling (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL)) staining method was employed to observe cell apoptosis, while Western blot to measure the expression of CBX7 and Nrf/HO-1 pathway-related proteins.

RESULTS

At 6 h, 12 h, 24 h, 3 days, and 7 days after mice with MCAO, CBX7 expression was gradually up-regulated and the peak level was reached at 24 h. Mice in the WT + MCAO group had increased infarct size, with significant increases in the modified neurological severity scores and water content in the brain, as well as the quantity of TUNEL-positive cells. For the oxidative stress-indicators, an increase was seen in the content of MDA (malondial dehyde), but the activity of SOD (superoxide dismutase) and content of GSH-PX (glutathione peroxidase) and CAT (catalase) were decreased; meanwhile, the protein expression of CBX7, HO-1, and nuclear Nrf2 was up-regulated, while the cytoplasmic Nrf2 was down-regulated. Moreover, CBX7 knockout attenuated I/R injury in mice.

CONCLUSION

Knockout of CBX7 may protect mice from cerebral I/R injury by reducing cell apoptosis and oxidative stress, possibly via activating the Nrf2/HO-1 pathway.

Effects of cannabinoid (CBD) on blood brain barrier permeability after brain injury in rats

Cannabidiol is a natural herbal medicine known to protect the brain from traumatic brain injury (TBI). Here, a TBI rat model was established, with cannabidiol administered intraperitoneally at doses of 5, 10, or 20 mg/kg, 30 min before surgery and 6 h after surgery until sacrifice. Brain water content, body weight, and modified neurological severity scores were determined, and enzyme-linked immunosorbent assay, immunofluorescence staining, hematoxylin and eosin staining, Nissl staining, Evans-blue dye extravasation, and western blotting were performed. Results showed that cannabidiol decreased the number of aquaporin-4-positive and glial fibrillary acidic protein-positive cells. Cannabidiol also significantly reduced the protein levels of proinflammatory cytokines (TNF-α and IL-1β) and significantly increased the expression of tight junction proteins (claudin-5 and occludin). Moreover, cannabidiol administration significantly mitigated water content in the brain after TBI and blood-brain barrier disruption and ameliorated the neurological deficit score after TBI. Cannabidiol administration improved the integrity and permeability of the blood-brain barrier and reduced edema in the brain after TBI.

Novel therapeutics for hydrocephalus: Insights from animal models

Hydrocephalus is a cerebrospinal fluid physiological disorder that causes ventricular dilation with normal or high intracranial pressure. The current regular treatment for hydrocephalus is cerebrospinal fluid shunting, which is frequently related to failure and complications. Meanwhile, considering that the current nonsurgical treatments of hydrocephalus can only relieve the symptoms but cannot eliminate this complication caused by primary brain injuries, the exploration of more effective therapies has become the focus for many researchers. In this article, the current research status and progress of nonsurgical treatment in animal models of hydrocephalus are reviewed to provide new orientations for animal research and clinical practice.

White matter injury in infants with intraventricular haemorrhage: mechanisms and therapies

Intraventricular haemorrhage (IVH) continues to be a major complication of prematurity that can result in cerebral palsy and cognitive impairment in survivors. No optimal therapy exists to prevent IVH or to treat its consequences. IVH varies in severity and can present as a bleed confined to the germinal matrix, small-to-large IVH or periventricular haemorrhagic infarction. Moderate-to-severe haemorrhage dilates the ventricle and damages the periventricular white matter. This white matter injury results from a constellation of blood-induced pathological reactions, including oxidative stress, glutamate excitotoxicity, inflammation, perturbed signalling pathways and remodelling of the extracellular matrix. Potential therapies for IVH are currently undergoing investigation in preclinical models and evidence from clinical trials suggests that stem cell treatment and/or endoscopic removal of clots from the cerebral ventricles could transform the outcome of infants with IVH. This Review presents an integrated view of new insights into the mechanisms underlying white matter injury in premature infants with IVH and highlights the importance of early detection of disability and immediate intervention in optimizing the outcomes of IVH survivors.

ATP Stimulation Promotes Functional Recovery after Intracerebral Haemorrhage by Increasing the mBDNF/proBDNF Ratio

Brain-derived neurotrophic factor (BDNF), including mature BDNF (mBDNF) and precursor BDNF (proBDNF), plays a pivotal role in neuronal survival, synaptic plasticity and neurogenesis. However, the functional effect of the mBDNF/proBDNF ratio in haemorrhagic stroke remains unclear. ATP is a known mediator of BDNF production in neurons and glia. Therefore, we hypothesized that ATP could facilitate BDNF production, increase the mBDNF/proBDNF ratio and thereby alleviate cerebral haemorrhage-induced injury. In this experiment, a model of intracerebral haemorrhage (ICH) was produced by injecting 50 μL autologous blood into the right corpus striatum in healthy male rats. ATP was injected to promote BDNF production and increase the mBDNF/proBDNF ratio. After ATP pretreatment, P2X4R-shRNA and SB203580 were used to inhibit P2X4R and p38-MAPK, respectively. We provide direct evidence that ATP administration was successful in promoting mBDNF expression and increasing the mBDNF/proBDNF ratio after ICH injury. Additionally, ATP stimulation could significantly improve cerebral neurological function and alleviate neuronal damage. Furthermore, ATP injection was able to upregulate the expression of P2X4R and p-p38-MAPK. Moreover, both P2X4R-shRNA and SB203580 could effectively abolish the effect of ATP injection on the levels of P2X4R and p-p38-MAPK and the mBDNF/proBDNF ratio. Together, these findings show that ATP stimulation contributes to functional recovery after cerebral haemorrhage and that neuroprotection induced by ATP administration in ICH rats is accompanied by a strong increase in the mBDNF/proBDNF ratio. Here, we also show a significant role of P2X4R-p38-MAPK signalling in the ATP-induced increase in the mBDNF/proBDNF ratio in ICH.

Germinal Matrix-Intraventricular Hemorrhage of the Preterm Newborn and Preclinical Models: Inflammatory Considerations

The germinal matrix-intraventricular hemorrhage (GM-IVH) is one of the most important complications of the preterm newborn. Since these children are born at a critical time in brain development, they can develop short and long term neurological, sensory, cognitive and motor disabilities depending on the severity of the GM-IVH. In addition, hemorrhage triggers a microglia-mediated inflammatory response that damages the tissue adjacent to the injury. Nevertheless, a neuroprotective and neuroreparative role of the microglia has also been described, suggesting that neonatal microglia may have unique functions. While the implication of the inflammatory process in GM-IVH is well established, the difficulty to access a very delicate population has lead to the development of animal models that resemble the pathological features of GM-IVH. Genetically modified models and lesions induced by local administration of glycerol, collagenase or blood have been used to study associated inflammatory mechanisms as well as therapeutic targets. In the present study we review the GM-IVH complications, with special interest in inflammatory response and the role of microglia, both in patients and animal models, and we analyze specific proteins and cytokines that are currently under study as feasible predictors of GM-IVH evolution and prognosis.

Intraventricular Hemorrhage and White Matter Injury in Preclinical and Clinical Studies

Germinal matrix-intraventricular hemorrhage (IVH) occurs in nearly half of infants born at less than 26 weeks' gestation. Up to 50% of survivors with IVH develop cerebral palsy, cognitive deficits, behavioral disorders, posthemorrhagic ventricular dilatation, or a combination of these sequelae. After the initial bleeding and the primary brain injury, inflammation and secondary brain injury might lead to periventricular leukomalacia or diffuse white matter injury. Potential factors that are involved include microglia and astrocyte activation, degradation of blood components with release of "toxic" products, infiltration of the brain by systemic immune cells, death of neuronal and glial cells, and arrest of preoligodendrocyte maturation. In addition, impairment of the blood-brain barrier may play a major role in the pathophysiology. A wide range of animal models has been used to explore causes and mechanisms leading to IVH-induced brain injury. Preclinical studies have identified potential targets for enhancing brain repair. However, little has been elucidated about the effectiveness of potential interventions in clinical studies. A systematic review of available preclinical and clinical studies might help identify research gaps and which types of interventions may be prioritized. Future trials should report clinically robust and long-term outcomes after IVH.

Inflammation in acquired hydrocephalus: pathogenic mechanisms and therapeutic targets

Hydrocephalus is the most common neurosurgical disorder worldwide and is characterized by enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles resulting from failed CSF homeostasis. Since the 1840s, physicians have observed inflammation in the brain and the CSF spaces in both posthaemorrhagic hydrocephalus (PHH) and postinfectious hydrocephalus (PIH). Reparative inflammation is an important protective response that eliminates foreign organisms, damaged cells and physical irritants; however, inappropriately triggered or sustained inflammation can respectively initiate or propagate disease. Recent data have begun to uncover the molecular mechanisms by which inflammation - driven by Toll-like receptor 4-regulated cytokines, immune cells and signalling pathways - contributes to the pathogenesis of hydrocephalus. We propose that therapeutic approaches that target inflammatory mediators in both PHH and PIH could address the multiple drivers of disease, including choroid plexus CSF hypersecretion, ependymal denudation, and damage and scarring of intraventricular and parenchymal (glia-lymphatic) CSF pathways. Here, we review the evidence for a prominent role of inflammation in the pathogenic mechanism of PHH and PIH and highlight promising targets for therapeutic intervention. Focusing research efforts on inflammation could shift our view of hydrocephalus from that of a lifelong neurosurgical disorder to that of a preventable neuroinflammatory condition.

Suppression of iron mobilization from lysosomes to mitochondria attenuates liver injury after acetaminophen overdose in vivo in mice: Protection by minocycline

Acetaminophen (APAP) overdose causes hepatotoxicity involving mitochondrial dysfunction. Previous studies showed that translocation of Fe²⁺ from lysosomes into mitochondria by the mitochondrial Ca²⁺ uniporter (MCU) promotes the mitochondrial permeability transition (MPT) after APAP. Here, our Aim was to assess protection by iron chelation and MCU inhibition against APAP hepatotoxicity in mice. C57BL/6 mice and hepatocytes were administered toxic doses of APAP with and without starch-desferal (an iron chelator), minocycline (MCU inhibitor), or N-acetylcysteine (NAC). In mice, starch-desferal and minocycline pretreatment decreased ALT and liver necrosis after APAP by >60%. At 24 h after APAP, loss of fluorescence of mitochondrial rhodamine 123 occurred in pericentral hepatocytes often accompanied by propidium iodide labeling, indicating mitochondrial depolarization and cell death. Starch-desferal and minocycline pretreatment decreased mitochondrial depolarization and cell death by more than half. In cultured hepatocytes, cell killing at 10 h after APAP decreased from 83% to 49%, 35% and 27%, respectively, by 1 h posttreatment with minocycline, NAC, and minocycline plus NAC. With 4 h posttreatment in vivo, minocycline and minocycline plus NAC decreased ALT and necrosis by ~20% and ~50%, respectively, but NAC alone was not effective. In conclusion, minocycline and starch-desferal decrease mitochondrial dysfunction and severe liver injury after APAP overdose, suggesting that the MPT is likely triggered by iron uptake into mitochondria through MCU. In vivo, minocycline and minocycline plus NAC posttreatment after APAP protect at later time points than NAC alone, indicating that minocycline has a longer window of efficacy than NAC.

Effects of minocycline on epiplexus macrophage activation, choroid plexus injury and hydrocephalus development in spontaneous hypertensive rats

Hydrocephalus has been reported to occur in spontaneous hypertensive rats (SHRs). The purposes of this study were (1) to use T2 magnetic resonance imaging to examine time of onset, (2) to elucidate potential underlying mechanisms and (3) to determine whether minocycline could prevent hydrocephalus development. Ventriculomegaly was evaluated by T2 imaging in SHRs and Wistar-Kyoto rats from weeks 4 to 7 after birth. Brain histology and transmission electron microscopy were used to assess the periventricular and choroid plexus damage. SHRs were also treated with either vehicle or minocycline. We found that hydrocephalus was observed in SHRs but not in Wistar-Kyoto rats. It occurred at seven weeks of age but was not present at four and five weeks. The hydrocephalus was associated with epiplexus cell (macrophage) activation, choroid plexus cell death and damage to the ventricle wall. Treatment with minocycline from week 5 attenuated hydrocephalus development and pathological changes in choroid plexus and ventricular wall at week 7. The current study found that spontaneous hydrocephalus arises at ∼7 weeks in male SHRs. The early development of hydrocephalus (persistent ventricular dilatation) may result from epiplexus cell activation, choroid plexus cell death and periventricular damage, which can be ameliorated by treatment with minocycline.

The heme and radical scavenger α1-microglobulin (A1M) confers early protection of the immature brain following preterm intraventricular hemorrhage

Background

Germinal matrix intraventricular hemorrhage (GM-IVH) is associated with cerebro-cerebellar damage in very preterm infants, leading to neurodevelopmental impairment. Penetration, from the intraventricular space, of extravasated red blood cells and extracellular hemoglobin (Hb), to the periventricular parenchyma and the cerebellum has been shown to be causal in the development of brain injury following GM-IVH. Furthermore, the damage has been described to be associated with the cytotoxic nature of extracellular Hb-metabolites. To date, there is no therapy available to prevent infants from developing either hydrocephalus or serious neurological disability. Mechanisms previously described to cause brain damage following GM-IVH, i.e., oxidative stress and Hb-metabolite toxicity, suggest that the free radical and heme scavenger α₁-microglobulin (A1M) may constitute a potential neuroprotective intervention.

Methods

Using a preterm rabbit pup model of IVH, where IVH was induced shortly after birth in pups delivered by cesarean section at E29 (3 days prior to term), we investigated the brain distribution of recombinant A1M (rA1M) following intracerebroventricular (i.c.v.) administration at 24 h post-IVH induction. Further, short-term functional protection of i.c.v.-administered human A1M (hA1M) following IVH in the preterm rabbit pup model was evaluated.

Results

Following i.c.v. administration, rA1M was distributed in periventricular white matter regions, throughout the fore- and midbrain and extending to the cerebellum. The regional distribution of rA1M was accompanied by a high co-existence of positive staining for extracellular Hb.

Administration of i.c.v.-injected hA1M was associated with decreased structural tissue and mitochondrial damage and with reduced mRNA expression for proinflammatory and inflammatory signaling-related genes induced by IVH in periventricular brain tissue.

Conclusions

The results of this study indicate that rA1M/hA1M is a potential candidate for neuroprotective treatment following preterm IVH.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1486-4) contains supplementary material, which is available to authorized users.

Intraventricular hemorrhage and posthemorrhagic hydrocephalus in preterm infants: diagnosis, classification, and treatment options

PURPOSE

Intraventricular hemorrhage is the most important adverse neurologic event for preterm and very low weight birth infants in the neonatal period. This pathology can lead to various delays in motor, language, and cognition development. The aim of this article is to give an overview of the knowledge in diagnosis, classification, and treatment options of this pathology.

METHOD

A systematic review has been made.

RESULTS

The cranial ultrasound can be used to identify the hemorrhage and grade it according to the modified Papile grading system. There is no standardized protocol of intervention as there are controversial results on which of the temporizing neurosurgical procedures is best and about the appropriate parameters to consider a conversion to ventriculoperitoneal shunt. However, it has been established that the most important prognosis factor is the involvement and damage of the white matter.

CONCLUSION

More evidence is required to create a standardized protocol that can ensure the best possible outcome for these patients.

Research Advances of Germinal Matrix Hemorrhage: An Update Review

Germinal matrix hemorrhage (GMH) refers to bleeding that derives from the subependymal (or periventricular) germinal region of the premature brain. GMH can induce severe and irreversible damage attributing to the vulnerable structure of germinal matrix and deleterious circumstances. Molecular mechanisms remain obscure so far. In this review, we summarized the newest preclinical discoveries recent years about GMH to distill a deeper understanding of the neuropathology, and then discuss the potential diagnostic or therapeutic targets among these pathways. GMH studies mostly in recent 5 years were sorted out and the authors generalized the newest discoveries and ideas into four parts of this essay. Intrinsic fragile structure of preterm germinal matrix is the fundamental cause leading to GMH. Many molecules have been found effective in the pathophysiological courses. Some of these molecules like minocycline are suggested active to reduce the damage in animal GMH model. However, researchers are still trying to find efficient diagnostic methods and remedies that are available in preterm infants to rehabilitate or cure the sequent injury. Merits have been obtained in the last several years on molecular pathways of GMH, but more work is required to further unravel the whole pathophysiology.

Cell Death Pathways: a Novel Therapeutic Approach for Neuroscientists

In the first part, the following mechanisms involved in different forms of cell death are considered, with a view to identifying potential therapeutic targets: tumour necrosis factor receptors (TNFRs) and their engagement by tumour necrosis factor-alpha (TNF-α); poly [ADP-ribose] polymerase (PARP)-1 cleavage; the apoptosis signalling kinase (ASK)-c-Jun N-terminal kinase (JNK) axis; lysosomal permeability; activation of programmed necrotic cell death; oxidative stress, caspase-3 inhibition and parthanatos; activation of inflammasomes by reactive oxygen species and the development of pyroptosis; oxidative stress, calcium dyshomeostasis and iron in the development of lysosomal-mediated necrosis and lysosomal membrane permeability; and oxidative stress, lipid peroxidation, iron dyshomeostasis and ferroptosis. In the second part, there is a consideration of the role of lethal and sub-lethal activation of these pathways in the pathogenesis and pathophysiology of neurodegenerative and neuroprogressive disorders, with particular reference to the TNF-α-TNFR signalling axis; dysregulation of ASK-1-JNK signalling; prolonged or chronic PARP-1 activation; the role of pyroptosis and chronic inflammasome activation; and the roles of lysosomal permeabilisation, necroptosis and ferroptosis. Finally, it is suggested that, in addition to targeting oxidative stress and inflammatory processes generally, neuropsychiatric disorders may respond to therapeutic targeting of TNF-α, PARP-1, the Nod-like receptor NLRP3 inflammasome and the necrosomal molecular switch receptor-interacting protein kinase-3, since their widespread activation can drive and/or exacerbate peripheral inflammation and neuroinflammation even in the absence of cell death. To this end, the use is proposed of a combination of the tetracycline derivative minocycline and N-acetylcysteine as adjunctive treatment for a range of neuropsychiatric disorders.

Opportunities in posthemorrhagic hydrocephalus research: outcomes of the Hydrocephalus Association Posthemorrhagic Hydrocephalus Workshop

The Hydrocephalus Association Posthemorrhagic Hydrocephalus Workshop was held on July 25 and 26, 2016 at the National Institutes of Health. The workshop brought together a diverse group of researchers including pediatric neurosurgeons, neurologists, and neuropsychologists with scientists in the fields of brain injury and development, cerebrospinal and interstitial fluid dynamics, and the blood-brain and blood-CSF barriers. The goals of the workshop were to identify areas of opportunity in posthemorrhagic hydrocephalus research and encourage scientific collaboration across a diverse set of fields. This report details the major themes discussed during the workshop and research opportunities identified for posthemorrhagic hydrocephalus. The primary areas include (1) preventing intraventricular hemorrhage, (2) stopping primary and secondary brain damage, (3) preventing hydrocephalus, (4) repairing brain damage, and (5) improving neurodevelopment outcomes in posthemorrhagic hydrocephalus.

Challenges for intraventricular hemorrhage research and emerging therapeutic targets

INTRODUCTION

Intraventricular hemorrhage (IVH) affects both premature infants and adults. In both demographics, it has high mortality and morbidity. There is no FDA approved therapy that improves neurological outcome in either population highlighting the need for additional focus on therapeutic targets and treatments emerging from preclinical studies. Areas covered: IVH induces both initial injury linked to the physical effects of the blood (mass effect) and secondary injury linked to the brain response to the hemorrhage. Preclinical studies have identified multiple secondary injury mechanisms following IVH, and particularly the role of blood components (e.g. hemoglobin, iron, thrombin). This review, with an emphasis on pre-clinical IVH research, highlights therapeutic targets and treatments that may be of use in prevention, acute care, or repair of damage. Expert opinion: An IVH is a potentially devastating event. Progress has been made in elucidating injury mechanisms, but this has still to translate to the clinic. Some pathways involved in injury also have beneficial effects (coagulation cascade/inflammation). A greater understanding of the downstream pathways involved in those pathways may allow therapeutic development. Iron chelation (deferoxamine) is in clinical trial for intracerebral hemorrhage and preclinical data suggest it may be a potential treatment for IVH.

Cerebellar Exposure to Cell-Free Hemoglobin Following Preterm Intraventricular Hemorrhage: Causal in Cerebellar Damage?

Decreased cerebellar volume is associated with intraventricular hemorrhage (IVH) in very preterm infants and may be a principal component in neurodevelopmental impairment. Cerebellar deposition of blood products from the subarachnoid space has been suggested as a causal mechanism in cerebellar underdevelopment following IVH. Using the preterm rabbit pup IVH model, we evaluated the effects of IVH induced at E29 (3 days prior to term) on cerebellar development at term-equivalent postnatal day 0 (P0), term-equivalent postnatal day 2 (P2), and term-equivalent postnatal day 5 (P5). Furthermore, the presence of cell-free hemoglobin (Hb) in cerebellar tissue was characterized, and cell-free Hb was evaluated as a causal factor in the development of cerebellar damage following preterm IVH. IVH was associated with a decreased proliferative (Ki67-positive) portion of the external granular layer (EGL), delayed Purkinje cell maturation, and activated microglia in the cerebellar white matter. In pups with IVH, immunolabeling of the cerebellum at P0 demonstrated a widespread presence of cell-free Hb, primarily distributed in the white matter and the molecular layer. Intraventricular injection of the Hb scavenger haptoglobin (Hp) resulted in a corresponding distribution of immunolabeled Hp in the cerebellum and a partial reversal of the damaging effects observed following IVH. The results suggest that cell-free Hb is causally involved in cerebellar damage following IVH and that blocking cell-free Hb may have protective effects.

Biomarkers in adult posthemorrhagic hydrocephalus

Posthemorrhagic hydrocephalus is a severe complication following intracranial hemorrhage. Posthemorrhagic hydrocephalus is often associated with high morbidity and mortality and serves as an important clinical predictor of adverse outcomes after intracranial hemorrhage. Currently, no effective medical intervention exists to improve functional outcomes in posthemorrhagic hydrocephalus patients because little is still known about the mechanisms of posthemorrhagic hydrocephalus pathogenesis. Because a better understanding of the posthemorrhagic hydrocephalus pathogenesis would facilitate development of clinical treatments, this is an active research area. The purpose of this review is to describe recent progress in elucidation of molecular mechanisms that cause posthemorrhagic hydrocephalus. What we are certain of is that the entry of blood into the ventricular system and subarachnoid space results in release of lytic blood products which cause a series of physiological and pathological changes in the brain. Blood components that can be linked to pathology would serve as disease biomarkers. From studies of posthemorrhagic hydrocephalus, such biomarkers are known to mutually synergize to initiate and promote posthemorrhagic hydrocephalus progression. These findings suggest that modulation of biomarker expression or function may benefit posthemorrhagic hydrocephalus patients.

Inflammatory Regulation by Driving Microglial M2 Polarization: Neuroprotective Effects of Cannabinoid Receptor-2 Activation in Intracerebral Hemorrhage

The cannabinoid receptor-2 (CB2R) was initially thought to be the “peripheral cannabinoid receptor.” Recent studies, however, have documented CB2R expression in the brain in both glial and neuronal cells, and increasing evidence suggests an important role for CB2R in the central nervous system inflammatory response. Intracerebral hemorrhage (ICH), which occurs when a diseased cerebral vessel ruptures, accounts for 10–15% of all strokes. Although surgical techniques have significantly advanced in the past two decades, ICH continues to have a high mortality rate. The aim of this study was to investigate the therapeutic effects of CB2R stimulation in acute phase after experimental ICH in rats and its related mechanisms. Data showed that stimulation of CB2R using a selective agonist, JWH133, ameliorated brain edema, brain damage, and neuron death and improved neurobehavioral outcomes in acute phase after ICH. The neuroprotective effects were prevented by SR144528, a selective CB2R inhibitor. Additionally, JWH133 suppressed neuroinflammation and upregulated the expression of microglial M2-associated marker in both gene and protein level. Furthermore, the expression of phosphorylated cAMP-dependent protein kinase (pPKA) and its downstream effector, cAMP-response element binding protein (CREB), were facilitated. Knockdown of CREB significantly inversed the increase of M2 polarization in microglia, indicating that the JWH133-mediated anti-inflammatory effects are closely associated with PKA/CREB signaling pathway. These findings demonstrated that CB2R stimulation significantly protected the brain damage and suppressed neuroinflammation by promoting the acquisition of microglial M2 phenotype in acute stage after ICH. Taken together, this study provided mechanism insight into neuroprotective effects by CB2R stimulation after ICH.

Fingolimod confers neuroprotection through activation of Rac1 after experimental germinal matrix hemorrhage in rat pups

Fingolimod, a sphingosine-1-phosphate receptor (S1PR) agonist, is clinically available to treat multiple sclerosis and is showing promise in treating stroke. We investigated if fingolimod provides long-term protection from experimental neonatal germinal matrix hemorrhage (GMH), aiming to support a potential mechanism of acute fingolimod-induced protection. GMH was induced in P7 rats by infusion of collagenase (0.3 U) into the right ganglionic eminence. Animals killed at 4 weeks post-GMH received low- or high-dose fingolimod (0.25 or 1.0 mg/kg) or vehicle, and underwent neurocognitive testing before histopathological evaluation. Subsequently, a cohort of animals killed at 72 h post-GMH received 1.0 mg/kg fingolimod; the specific S1PR1 agonist, SEW2871; or fingolimod co-administered with the S1PR1/3/4 inhibitor, VPC23019, or the Rac1 inhibitor, EHT1864. All drugs were injected intraperitoneally 1, 24, and 48 h post-surgery. At 72 h post-GMH, brain water content, extravasated Evans blue dye, and hemoglobin were measured as well as the expression levels of phospho-Akt, Akt, GTP-Rac1, Total-Rac1, ZO1, occludin, and claudin-3 determined. Fingolimod significantly improved long-term neurocognitive performance and ameliorated brain tissue loss. At 72 h post-GMH, fingolimod reduced brain water content and Evans blue dye extravasation as well as reversed GMH-induced loss of tight junctional proteins. S1PR1 agonism showed similar protection, whereas S1PR or Rac1 inhibition abolished the protective effect of fingolimod. Fingolimod treatment improved functional and morphological outcomes after GMH, in part, by tempering acute post-hemorrhagic blood-brain barrier disruption via the activation of the S1PR1/Akt/Rac1 pathway.

Post-hemorrhagic hydrocephalus: Recent advances and new therapeutic insights

Post-hemorrhagic hydrocephalus (PHH), also referred to as progressive ventricular dilatation, is caused by disturbances in cerebrospinal fluid (CSF) flow or absorption following hemorrhage in the brain. As one of the most serious complications of neonatal/adult intraventricular hemorrhage (IVH), subarachnoid hemorrhage (SAH), and traumatic brain injury (TBI), PHH is associated with increased morbidity and disability of these events. Common sequelae of PHH include neurocognitive impairment, motor dysfunction, and growth impairment. Non-surgical measures to reduce increased intracranial pressure (ICP) in PHH have shown little success and most patients will ultimately require surgical management, such as external ventricular drainage and shunting which mostly by inserting a CSF drainage shunt. Unfortunately, shunt complications are common and the optimum time for intervention is unclear. To date, there remains no comprehensive strategy for PHH management and it becomes imperative that to explore new therapeutic targets and methods for PHH. Over past decades, increasing evidence have indicated that hemorrhage-derived blood and subsequent metabolic products may play a key role in the development of IVH-, SAH- and TBI-associated PHH. Several intervention strategies have recently been evaluated and cross-referenced. In this review, we summarized and discussed the common aspects of hydrocephalus following IVH, SAH and TBI, relevant experimental animal models, clinical translation of in vivo experiments, and potential preventive and therapeutic targets for PHH.

Urokinase, a promising candidate for fibrinolytic therapy for intracerebral hemorrhage

OBJECTIVE Intracerebral hemorrhage (ICH) is associated with a high rate of mortality and severe disability, while fibrinolysis for ICH evacuation is a possible treatment. However, reported adverse effects can counteract the benefits of fibrinolysis and limit the use of tissue-type plasminogen activator (tPA). Identifying appropriate fibrinolytics is still needed. Therefore, the authors here compared the use of urokinase-type plasminogen activator (uPA), an alternate thrombolytic, with that of tPA in a preclinical study. METHODS Intracerebral hemorrhage was induced in adult male Sprague-Dawley rats by injecting autologous blood into the caudate, followed by intraclot fibrinolysis without drainage. Rats were randomized to receive uPA, tPA, or saline within the clot. Hematoma and perihematomal edema, brain water content, Evans blue fluorescence and neurological scores, matrix metalloproteinases (MMPs), MMP mRNA, blood-brain barrier (BBB) tight junction proteins, and nuclear factor-κB (NF-κB) activation were measured to evaluate the effects of these 2 drugs in ICH. RESULTS In comparison with tPA, uPA better ameliorated brain edema and promoted an improved outcome after ICH. In addition, uPA therapy more effectively upregulated BBB tight junction protein expression, which was partly attributed to the different effects of uPA and tPA on the regulation of MMPs and its related mRNA expression following ICH. CONCLUSIONS This study provided evidence supporting the use of uPA for fibrinolytic therapy after ICH. Large animal experiments and clinical trials are required to further explore the efficacy and safety of uPA in ICH fibrinolysis.

Nonsurgical therapy for hydrocephalus: a comprehensive and critical review

Pharmacological interventions have been tested experimentally and clinically to prevent hydrocephalus and avoid the need for shunting beginning in the 1950s. Clinical trials of varied quality have not demonstrated lasting and convincing protective effects through manipulation of cerebrospinal fluid production, diuresis, blood clot fibrinolysis, or manipulation of fibrosis in the subarachnoid compartment, although there remains some promise in the latter areas. Acetazolamide bolus seems to be useful for predicting shunt response in adults with hydrocephalus. Neuroprotection in the situation of established hydrocephalus has been tested experimentally beginning more recently. Therapies designed to modify blood flow or pulsation, reduce inflammation, reduce oxidative damage, or protect neurons are so far of limited success; more experimental work is needed in these areas. As has been recommended for preclinical studies in stroke and brain trauma, stringent conditions should be met for preclinical studies in hydrocephalus.

Pharmacological Preventions of Brain Injury Following Experimental Germinal Matrix Hemorrhage: an Up-to-Date Review

Germinal matrix hemorrhage (GMH) is defined as the rupture of immature blood vessels in the subependymal zone of premature infants with significant mortality and morbidity. Considering the notable social and ecological stress brought by GMH-induced brain injury and sequelae, safe and efficient pharmacological preventions are badly needed. Currently, several appropriate animal models are available to mimic the clinical outcomes of GMH in human patients. In the long run, hemorrhagic strokes are the research target. Previously, we found that minocycline was efficient to alleviate GMH-induced brain edema and posthemorrhagic hydrocephalus (PHH) in rats, which may be closely related to the activation of cannabinoid receptor 2 (CB2R). However, how the two molecules correlate and the underlined molecular pathway remain unknown. To extensively understand current experimental GMH treatment, this literature review critically evaluates existing therapeutic strategies, potential treatments, and potentially involved molecular mechanisms. Each strategy has its own advantages and disadvantages. Some of the mechanisms are still controversial, requiring an increasing number of animal experiments before the therapeutic strategy would be widely accepted.

Intracerebral Hematoma Contributes to Hydrocephalus After Intraventricular Hemorrhage via Aggravating Iron Accumulation

BACKGROUND AND PURPOSE

The intraventricular hemorrhage (IVH) secondary to intracerebral hemorrhage (ICH) was reported to be relevant to a higher incidence of hydrocephalus, which would result in poorer outcomes for patients with ICH. However, the mechanisms responsible for this relationship remain poorly characterized. Thus, this study was designed to further explore the development and progression of hydrocephalus after secondary IVH.

METHODS

Autologous blood injection model was induced to mimic ICH with ventricular extension (ICH/IVH) or primary IVH in Sprague-Dawley rats. Magnetic resonance imaging, Morris water maze, brain water content, Evans blue extravasation, immunohistochemistry staining, Western blot, iron determination, and electron microscopy were used in these rats. Then, deferoxamine treatment was used to clarify the involvement of iron in the development of hydrocephalus.

RESULTS

Despite the injection of equivalent blood volumes, ICH/IVH resulted in more significant ventricular dilation, ependymal cilia damage, and iron overload, as well as more severe early brain injury and neurological deficits compared with IVH alone. Systemic deferoxamine treatment more effectively reduced ventricular enlargement in ICH/IVH compared with primary IVH.

CONCLUSIONS

Our results show that ICH/IVH caused more significant chronic hydrocephalus and iron accumulation than primary IVH alone. Intracerebral hematoma plays a vital role in persistent iron overload and aggravated hydrocephalus after ICH/IVH.

Cannabinoid receptor 2 attenuates microglial accumulation and brain injury following germinal matrix hemorrhage via ERK dephosphorylation in vivo and in vitro

Microglia accumulation plays detrimental roles in the pathology of germinal matrix hemorrhage (GMH) in the immature preterm brain. However, the underlying mechanisms remain poorly defined. Here, we investigated the effects of a cannabinoid receptor 2 (CB2R) agonist on microglia proliferation and the possible involvement of the mitogen-activated protein kinase (MAPK) family pathway in a collagenase-induced GMH rat model and in thrombin-induced rat microglia cells. We demonstrated that activation of CB2R played a key role in attenuating brain edema, neuronal degeneration, microglial accumulation and the phosphorylated extracellular signal-regulated kinase (p-ERK) protein level 24 h following GMH. In vitro, Western blot analysis and immunostaining indicated that ERK and P38 phosphorylation levels in microglia stimulated by thrombin were decreased after JWH-133 (CB2R selective agonist) treatment in a concentration-dependent manner. Microglia proliferation (EDU + microglia) and inflammatory and oxidative stress responses were attenuated by UO126 (ERK pathway inhibitor) 24 h after thrombin stimulation, an activity that was prevented by AM630 (CB2R selective antagonist). Overall, these findings suggest that activation of the endocannabinoid system might attenuate inflammation-induced secondary brain injury after GMH in rats by reducing microglia accumulation through a mechanism involving ERK dephosphorylation. Enhancing CB2R activation is a potential treatment to slow down the course of GMH in preterm newborns.