Cerebral Water Research Articles

Correction of the disorders of the cerebral water metabolism

The new information, that has become available at present, makes it possible to outline a mechanism of brain water metabolism in the realization of which an important role belongs to AQP4, the main aquaporin of the brain. This aquaporin controls water transfer across the blood-brain barrier and water exchange between brain parenchyma and the cerebrospinal fluid. In the world literature, AQP4 is viewed as a molecular target for the drug action directed at correction of the brain water metabolism disorders in pathologies. The new knowledge made it possible to outline principal approaches to pharmacological correction of cerebral water metabolism disorders and edema.

Determining T2 relaxation time and stroke onset relationship in ischaemic stroke within apparent diffusion coefficient-defined lesions. A user-independent method for quantifying the impact of stroke in the human brain.

In hyperacute ischaemic stroke, T2 of cerebral water increases with time. Quantifying this change may be informative of the extent of tissue damage and onset time. Our objective was to develop a user-unbiased method to measure the effect of cerebral ischaemia on T2 to study stroke onset time-dependency in human acute stroke lesions. Six rats were subjected to permanent middle cerebral occlusion to induce focal ischaemia, and a consecutive cohort of acute stroke patients (n = 38) were recruited within 9 hours from symptom onset. T1-weighted structural, T2 relaxometry, and diffusion MRI for apparent diffusion coefficient (ADC) were acquired. Ischaemic lesions were defined as regions of lowered ADC. The median T2 difference (ΔT2) between lesion and contralateral non-ischaemic control region was determined by the newly-developed spherical reference method, and data compared to that obtained by the mirror reference method. Linear regressions and receiver operating characteristics (ROC) were compared between the two methods. ΔT2 increases linearly in rat brain ischaemia by 1.9 ± 0.8 ms/h during the first 6 hours, as determined by the spherical reference method. In patients, ΔT2 linearly increases by 1.6 ± 1.4 and 1.9 ± 0.9 ms/h in the lesion, as determined by the mirror reference and spherical reference method, respectively. ROC analyses produced areas under the curve of 0.83 and 0.71 for the spherical and mirror reference methods, respectively. Data from the spherical reference method showed that the median T2 increase in the ischaemic lesion is correlated with stroke onset time in a rat as well as in a human patient cohort, opening the possibility of using the approach as a timing tool in clinics.

Resveratrol downregulates the TLR4 signaling pathway to reduce brain damage in a rat model of focal cerebral ischemia.

Previous studies have demonstrated that inflammation and disruption of the blood-brain barrier (BBB) are important pathological processes during focal cerebral ischemia. Therefore, the present study evaluated the neuroprotective effects of resveratrol against brain damage, inflammation and BBB disruption in rats with focal cerebral ischemia and assessed the potential underlying molecular mechanisms. Sprague-Dawley rats underwent cerebral ischemia/reperfusion (IR) and then received intraperitoneal resveratrol (10 and 100 mg/kg) 2 h following the onset of ischemia. Following 24 h of ischemia, neurological deficit scores, cerebral infarctions, morphological characteristics, cerebral water content, myeloperoxidase (MPO) activity and Evans blue extravasation were assessed. Additionally, the protein expression levels of Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB p65 were detected using western blot analyses, the mRNA expression levels of cyclooxygenase-2 (COX-2) and matrix metalloproteinase-9 (MMP-9) were examined by reverse-transcription polymerase chain reaction, and tumor necrosis factor (TNF)-α and interleukin (IL)-1β blood levels were determined by ELISA. Resveratrol significantly reduced neurological deficit scores, cerebral infarct sizes, neuronal injury, MPO activity and EB content. Cerebral ischemia increased the expression levels of TLR4, NF-κB p65, COX-2, MMP-9, TNF-α and IL-1β, but all of these factors were reduced by resveratrol. In conclusion, the present data suggest that resveratrol reduces inflammation, BBB disruption and brain damage in rats following focal cerebral ischemia. Additionally, the neuroprotective effects of resveratrol against cerebral ischemia may be associated with downregulation of the TLR4 pathway.

Inhibition of the PI3K/Akt signaling pathway impedes the restoration of neurological function following hypoxic-ischemic brain damage in a neonatal rabbit model.

Hypoxic-ischemic brain damage (HIBD), frequently occurring in infancy and childhood, is a major cause of mortality and severe neurologic impairment. This study was performed to examine the effect of the PI3K/Akt signaling pathway on HIBD in a neonatal rabbit model. Uterine artery occlusion was used to establish HIBD models in neonatal rabbits, which were then subjected to sham operation, dimethyl sulfoxide (2 mL) or LY294002 (inhibitor of PI3K/Akt signaling pathway, 6.4 μg/kg). Behavioral neurological assessment was performed in neonatal rabbits delivered by cesarean section, after which serum neuron-specific enolase (NSE) level and cerebral water content were determined. The level of cleaved caspase-3 level and apoptosis of neurons were observed by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Furthermore, the expression of PI3K/Akt signaling pathway- and apoptosis-related factors was examined. In neonatal rabbits, HIBD increased the fetal death rate; reduced neurological scores of posture, righting reflex, and deglutition reflex; elevated serum NSE levels, cerebral water content, cleaved caspase-3-positive expression in hippocampal CA1 region and apoptotic neurons; inactivated PI3K/Akt signaling pathway as well as reduced Bcl-2 expression and increased BAD and Bax expression. Notably, the treatment of LY294002 further aggravated neurological impairment in neonatal rabbits in response to HIBD. Following the HIBD caused by intrauterine asphyxia, the LY294002 administered through auricular vein infusion into pregnant rabbits exacerbates neurological impairment of neonatal rabbits, suggesting that inhibition of PI3K/Akt signaling pathway may serve as a candidate therapeutic target for neurological recovery.

Effects of icariside II on brain tissue oxidative stress and Nrf2/HO-1 expression in rats with cerebral ischemia-reperfusion injury1.

Purpose To investigate the effects of icariside II on brain tissue oxidative stress and Nrf2/HO-1 expression in rats with cerebral ischemia-reperfusion injury (CIRI). MethodsOne hundred SD rats were randomly divided into sham-operated, model, and 5, 10 and 20 mg/kg icariside II groups, 20 rats in each group. The middle cerebral artery occlusion model (ischemia for 2 h followed by reperfusion for 24 h) was established in the later 4 groups. In later 3 groups, at reperfusion beginning, the rats were intragastrically administrated with 5, 10 and 20 mg/kg icariside II, respectively. After 24 h of reperfusion, the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue oxidative stress indexes and Nrf2 and HO-1 protein expressions were determined. ResultsCompared with model group, in 20 mg/kg icariside II group the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue ROS content and MDA level were significantly decreased (P<0.05), and the brain tissue SOD, GSH-Px and catalase levels and Nrf2 and HO-1 protein levels were significantly increased (P<0.05). Conclusion Icariside II can alleviate the CIRI in rats through reducing brain tissue oxidative stress and improving Nrf2/HO-1 expression.

Protective effect of picroside Ⅱ on the brain tissue through antioxidation in stroke rats

Objective: To investigate the effect and mechanisms of picroside Ⅱ on the brain tissue after cerebral ischemia reperfusion(I/R) in rats. Methods: The middle cerebral artery occlusion(MCAO) rat model was established by inserting a monofilament into middle cerebral artery. The experimental rats were treated by injecting picroside Ⅱ intraperitoneally. The modified neurological severity score (mNSS) and body weight were determined before modeling and after reperfusion of 22 h. The cerebral infarct volume was measured by TTC staining and the cerebral water content was measured in rats. At the same time, ROS content and NADPH oxidase activity were detected. The structure of neurons was observed by electron microscope and the mRNA and protein levels of Rac-1 and Nox2 were detected by RT-PCR and Western blotting. Results: After modeling, the mNSS score was significantly increased (12.6±1.3 vs 0, P<0.001), while the body weight was lost (13.3%±2.5% vs 4.9%±0.8%, P<0.01). The cerebral infarct volume increased obviously (33.5%±3.4% vs 0, P<0.001), brain water content increased significantly (81.5%±0.9% vs 77.7%±0.9%, P<0.05) and the structure of neuron was damaged obviously. The protein and mRNA levels of Rac-1 and Nox2 were significantly increased (P<0.05). After treatment with picroside Ⅱ, mNSS score decreased significantly (7.9±0.8 vs 12.6±1.3, P<0.05) and the body weight increased obviously (9.3%±1.1% vs 13.3%±2.5%, P<0.05). The infarct volume of brain was significantly reduced (18.2%±1.9% vs 33.5%±3.4%, P<0.05), brain water content decreased obviously (79.1%±0.7% vs 81.5±0.9%, P<0.05), the morphological structures of neurons was restored, and the expressions of Rac-1 and Nox2 were significantly decreased (P<0.05). Conclusion: It is suggested that picroside Ⅱ could exert antioxidation to protect the brain tissue through inhibiting the expression of Rac-1 and Nox2.

The aquaporin-4 inhibitor AER-271 blocks acute cerebral edema and improves early outcome in a pediatric model of asphyxial cardiac arrest.

Background:Cerebral edema after cardiac arrest (CA) is associated with increased mortality and unfavorable outcome in children and adults. Aquaporin-4 mediates cerebral water movement and its absence in models of ischemia improves outcome. We investigated early and selective pharmacologic inhibition of aquaporin-4 in a clinically relevant asphyxial CA model in immature rats in a threshold CA insult that produces primarily cytotoxic edema in the absence of blood brain barrier permeability.Methods:Postnatal day 16–18 Sprague-Dawley rats were studied in our established 9-min asphyxial CA model. Rats were randomized to aquaporin-4 inhibitor (AER-271) vs vehicle treatment, initiated at return of spontaneous circulation. Cerebral edema (% brain water) was the primary outcome with secondary assessments of the neurologic deficit score (NDS), hippocampal neuronal death, and neuroinflammation.Results:Treatment with AER-271 ameliorated early cerebral edema measured at 3 h after CA vs. vehicle treated rats. This treatment also attenuated early NDS. In contrast to rats treated with vehicle after CA, rats treated with AER-271 did not develop significant neuronal death or neuroinflammation as compared to sham.Conclusion:Early post-resuscitation aquaporin-4 inhibition blocks the development of early cerebral edema, reduces early neurologic deficit, and blunts neuronal death and neuroinflammation post-CA.

MiR-590-5p alleviates intracerebral hemorrhage-induced brain injury through targeting Peli1 gene expression

Intracerebral haemorrhage (ICH) is a common and devastating cerebrovascular disease with high morbidity and mortality, and its pathophysiological mechanisms were complex and still unclear. Increasing researches reported that microRNAs (miRNAs) played an important role in ICH-induced brain injury and microglial activation. In this study, we investigated the biological function of miR-590-5p and explored its molecular mechanism in ICH mice. The results of qRT-PCR showed that miR-590-5p expression level was down-regulated in perihematomal brain samples of ICH mice compared with that of sham group. In LPS-induced microglia cells, miR-590-5p level was also down-regulated at 24 h post-LPS compared with that of control group. Moreover, miR-590-5p overexpression remarkably increased the cerebral water content and neurological severity scores compared with that of scramble group in ICH mice. The production of inflammatory cytokine including IL-6, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α in ICH mice was notably inhibited by miR-590-5p overexpression. Furthermore, the results of dual-luciferase reporter assay indicated that Pellino-1 (Peli1) was a direct target of miR-590-5p. MiR-590-5p overexpression remarkably inhibited the Peli1 gene expression both mRNA and protein levels. In addition, Peli1 overexpression partly abrogated the inhibitory effect of miR-590-5p mimic. Taken together, these datas suggested that miR-590-5p attenuated brain injury in ICH mice through inhibiting Peli1 gene expression, indicating that miR-590-5p may be a promising molecular target for ICH treatment.

Resveratrol attenuates brain damage in permanent focal cerebral ischemia via activation of PI3K/Akt signaling pathway in rats

ABSTRACTObjective: The aim of this study was to evaluate the potential molecular mechanism of resveratrol (RSV) that attenuates brain damage from focal cerebral ischemia.Methods and materials: To investigate whether phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway was involved in RSV anti-inflammatory and neuroprotective properties. Middle cerebral artery occlusion (MCAO) animal model was used in this study. Adult male Sprague–Dawley (SD) rats underwent MCAO, and then received treatment with RSV or vehicle after the onset of ischemia. PI3K inhibitor LY294002 was injected intracerebroventricularly to inhibit the PI3K/Akt signaling pathway. Neurological deficit scores and cerebral water content were assessed 24 h after MCAO. The inflammatory factors interleukin (IL)-1β, tumor necrosis factor (TNFα), and cyclooxygenase-2 (COX2) mRNA level were examined by real-time PCR. The enzymatic activity of myeloperoxidase (MPO) was measured 24 h after MCAO. The protein expression of phospho-Akt and COX2 in ischemic brain were determined by western blot.Results: RSV significantly reduced neurological deficit scores, cerebral water content and the enzymatic activity of MPO, all of which were abolished by LY294002 administration. Real-time PCR showed that RSV significantly suppressed the upregulation of the inflammatory factors IL-1β, TNFα, COX2 mRNA levels. RSV significantly inhibited upregulated the protein expression of COX2 24 h after MCAO, which effect was abolished by LY294002 administration.Conclusion: RSV attenuated ischemic brain damage induced by cerebral artery occlusion mainly through PI3K/Akt signaling pathway.Abbreviation: MCAO: Middle cerebral artery occlusion; RSV: resveratrol; PI3K/Akt: phosphatidylinositol 3-kinase/Akt; TNF: tumor necrosis factor; COX2: cyclooxygenase-2; MPO: myeloperoxidase; IL: interleukin.

Simvastatin improves cerebrovascular injury caused by ischemia‑reperfusion through NF‑κB‑mediated apoptosis via MyD88/TRIF signaling

Cerebrovascular injury is the most prevalent human cerebrovascular disease and frequently results in ischemic stroke. Simvastatin may be a potential therapeutic agent for the treatment of patients with cerebrovascular injury. The present study aimed to investigate the efficacy of and the potential mechanisms regulated by simvastatin in a rat model of ischemia-reperfusion (I/R)-induced cerebrovascular injury. Cerebrovascular injury model rats were established and were subsequently treated with simvastatin or a vehicle control following I/R injury. Cell damage, neurological functions and neuronal apoptosis were examined, as well as the nuclear factor (NF)-κB-mediated myeloid differentiation primary response protein 88 (MyD88)/toll-interleukin-1 receptor domain-containing adapter molecule 1 (TRIF) signaling pathway following simvastatin treatment. The results of the present study demonstrated that simvastatin treatment led to a reduction in cell damage, improvement of neurological functions and decreased neuronal apoptosis compared with vehicle-treated I/R model rats, 14 days post-treatment. In addition, simvastatin treatment reduced cerebral water content and blood-brain barrier disruption in cerebrovascular injury induced by I/R. The results also revealed that simvastatin treatment inhibited neuronal apoptosis via the NF-κB-mediated MyD88/TRIF signaling pathway. In conclusion, simvastatin treatment may reduce I/R-induced neuronal apoptosis via inhibition of the NF-κB-mediated MyD88/TRIF signaling pathway.

Effects of physiological ischemic training on post-stroke neuroprotection and angiogenesis in adult rats

To examine potentially beneficial effects of physiological ischemic training (PIT) following stroke. Three hundred seventy-five adult male rats were subjected to 90-min transient middle cerebral artery occlusion (MCAO) and randomized into a PIT group and a non-PIT control group. A sham-operated group was used as negative control. After 1- and 2-weeks of PIT, brain infarct volume was measured by Triphenyl tetrazolium chloride (TTC) staining, and behavioral outcomes, presence of intact neurons, apoptosis, and cerebral edema were assessed with modified neurological severity score (mNSS), Nissl staining, TdT-mediated dUTP Nick-End Labeling (TUNEL) staining and cerebral water volume. The mRNA expression of vascular endothelial growth factor (VEGF) was assayed with RT-PCR and protein expression of VEGF was quantified with Western blot. Cerebral infarction, neurological deficits and neuronal apoptosis were reduced significantly in the PIT groups, while the presence of neurons was increased in comparison with MCAO controls. Moreover, mRNA and protein expression of VEGF were enhanced after 1 and 2 weeks of PIT. PIT may promote angiogenesis and neuroprotection during post-stroke rehabilitation and provide a novel strategy for rehabilitation of stroke patients.

Ghrelin attenuates septic brain damage in mice

Objective To research the effect of ghrelin on sepsis-induced brain damage and the underlying mechanism by examining the integrity of the blood-brain barrier, cerebral water content, inflammatory cytokines (tumor necrosis factor α or TNF-α and interleukin-1β or IL-1β), oxidative stress, neuronal apoptosis, and p-Akt and anti-apoptotic proteins (Bcl-20) in the PI3K/AKt pathway. Methods Two hundred and forty male C57BL/6J mice were randomized into four groups: the control group, the operation group, the operation+ ghrelin group, and the operation+ ghrelin+ LY294002 (LY) group.Cecal ligation and puncture were performed in male C57BL/6 J mice to establish the sepsis model.Ghrelin was administrated intraperitoneally at a dose of 80 g/kg.Blood brain barrier (BBB) integrity, brain water content, inflammatory cytokines (TNF-α and IL-1β), oxidative stress (SOD and MDA), and neuronal apoptosis were assessed.In addition, the expression levels of Akt, phospho-Akt (Ser473) (p-Akt), Bcl-2, and Bax were detected by Western blot. Results The 7-day survival rate in the control group was 100%.At day 7 after CLP surgery, the survival rate decreased dramatically to 28% (versus the control group, P< 0.05). The survival rate increased markedly to 50% in the CLP + ghrelin group (versus the CLP group, P < 0.05). LY administration nullified the protective effect of ghrelin, as indicated by the decreased survival rate (24%) in the CLP + ghrelin + LY group (versus the CLP+ ghrelin group, P< 0.05). Ghrelin attenuated brain edema and neuronal apoptosis, but enhanced BBB integrity (all P< 0.05). It also increased the activity of SOD, and decreased the production of TNF-α, the production of IL-1β, and the level of MDA (all P< 0.05). In addition, Western blotting detected increased expression of p-Akt and Bcl-2 and decreased expression of Bax by Ghrelin (all P< 0.05). The protective effects of ghrelin observed above were nullified by LY, a PI3K inhibitor(P< 0.05). Conclusions Ghrelin alleviates brain damage in sepsis via PI3K/Akt signaling activation. Key words: Ghrelin; Sepsis; PI3K/Akt

Anti-inflammatory and anti-apoptotic effects of the combination of Ligusticum chuanxiong and Radix Paeoniae against focal cerebral ischaemia via TLR4/MyD88/MAPK/NF-κB signalling pathway in MCAO rats.

This study was performed to assess the anti-inflammatory and anti-apoptotic effects of the combination of Ligusticum chuanxiong and Radix Paeoniae (XS) on focal cerebral ischaemic stroke. MCAO rats were used to evaluate the effect of XS on stroke. Cerebral water content was measured, and the levels of IFN-γ, IL-1β, IL-6 and IL-12 in serum and brain were assessed by ELISA kits. Protein expressions including p-p38, p-38, TLR-4, p-ERK, ERK, TLR-5, NF-κBp65, Myd88, Caspase-3 and Caspase-12 were examined by WB and IHC. Q-PCR was applied to examine IL-1β and IL-6 mRNA levels in the rat brain of each group. XS treatment remarkedly decreased the levels of IFN-γ, IL-1β, IL-6 and IL-12 in serum and brain tissues of MCAO rats. In the ischaemic brain, the expressions of TLR-4, TLR-5, p-p38, p-ERK, Myd88, NF-κBp65, Caspase-3 and Caspase-12 were increased significantly, while the treatment attenuated the activated expressions by MCAO. XS also downregulated Caspase-3 and Caspase-12 expressions. IL-1β and IL-6 mRNA levels in MCAO brain tissue were decreased by XS treatment. XS could protect MCAO rats by anti-inflammation and anti-apoptosis through TLR4/MyD88/MAPK/NF-κB signalling pathway. Furthermore, the combination has a more meaningful improvement on focal cerebral ischaemic stroke.

Apocynin promotes neural function recovery and suppresses neuronal apoptosis by inhibiting Tlr4/NF-κB signaling pathway in a rat model of cerebral infarction

Occlusion of arteries in the brain is a common cause of cerebral infarction which induces inflammatory response and oxidative stress resulting in neuronal apoptosis and disruption of neurological function. The present study investigated the protective roles of an nicotinamide adenine dinucleotide phosphate oxidase inhibitor, apocynin, against cerebral infarction. Rat went through a surgery of middle cerebral artery occlusion and a subset of rats was treated with apocynin by intraperitoneal injection. The volume of cerebral infarction and water content were measured. Neuronal apoptosis, inflammatory response, and oxidative stress were assessed following middle cerebral artery occlusion and apocynin treatment. We found that apocynin significantly improved neurological function, increased forelimb placement test scores, and suppressed balance beam walk latency in rats with cerebral infarction. Histological and biochemistry analysis revealed that apocynin lead to a significant reduction in the volume of cerebral infarction as well as cerebral water content, suppressed neuronal apoptosis, oxidative stress, and inflammatory response induced by middle cerebral artery occlusion. Finally, we found that apocynin suppressed Tlr4/nuclear factor-k-gene binding signaling pathway that was upregulated in rats with cerebral infarction. Our results indicate that apocynin may represent a potent therapeutic strategy in alleviating neurological dysfunctions in patients with cerebral infarction.

Noninvasive monitoring of brain edema after hypoxia in newborn piglets.

BackgroundDevelopment of cerebral edema after brain injury carries a high risk for brain damage and death. The present study tests the ability of a noninvasive cerebral edema monitoring system that uses near-infrared spectroscopy (NIRS) with water as the chromophore of interest to detect brain edema following hypoxia.MethodsVentilated piglets were exposed to hypoxia for 1 h, and then returned to normal oxygen levels for 4 h. An NIRS sensor was placed on the animal's head at baseline, and changes in light attenuation were converted to changes in H2O. Cerebral water content and aquaporin-4 protein (AQP4) expression were measured.ResultsThe system detected changes in NIRS-derived water signal as early as 2 h after hypoxia, and provided fivefold signal amplification, representing a 10% increase in brain water content and a sixfold increase in AQP4, 4 h after hypoxia. Changes in water signal correlated well with changes in cerebral water content (R=0.74) and AQP4 expression (R=0.97) in the piglet brain.ConclusionThe data show that NIRS can detect cerebral edema early in the injury process, thus providing an opportunity to initiate therapy at an earlier and more effective time-point after an insult than is available with current technology.

Simvastatin improves intracerebral hemorrhage through NF-κB-mediated apoptosis via the MyD88/TRIF signaling pathway.

The aim was to investigate the neuroprotective effects and potential mechanism mediated by simvastatin in a mouse model of intracerebral hemorrhage. CD-1 mice were subjected to infusion of collagenase type IV into the left striatum in order to induce intracerebral hemorrhage. Western blot analysis, the TUNEL assay and the modified neurological severity score were used in the present study to analyze the efficacy of simvastatin for intracerebral hemorrhage. The results demonstrated that simvastatin treatment improved the cerebral water content and blood-brain barrier disruption in the intracerebral hemorrhage animals. Intracerebral hemorrhage-induced neuronal cell death was downregulated by simvastatin treatment compared with the vehicle-treated model group. In addition, the expression levels of aquaporin-4, matrix metallopeptidase 9 and caspase-3 were downregulated and B-cell lymphoma-2 was upregulated by simvastatin treatment compared with the vehicle-treated model. Simvastatin treatment also significantly reduced the Evans blue leakage into the injured hemispheres and improved motor function. Mechanism analysis further indicated that simvastatin treatment downregulated nuclear factor (NF)-κB expression, and upregulated the myeloid differentiation primary response 88 (MyD88) and TIR domain-containing adaptor protein inducing interferon-β (TRIF) expression levels in neuronal cells in experimental mice. Furthermore, the results revealed that NF-κB overexpression abolished the simvastatin-downregulated MyD88 and TRIF expression levels, as well as the apoptosis of neuronal cells. In conclusion, these results indicated that simvastatin was able to attenuate brain edema and reduce cellular apoptosis by suppressing the NF-κB-mediated MyD88/TRIF signaling pathway subsequent to the induction of intracerebral hemorrhage in mice.

Aortic Stiffness, Increased White Matter Free Water, and Altered Microstructural Integrity: A Continuum of Injury.

Previous reports from the Framingham Heart Study have identified cross-sectional associations of arterial stiffness, as reflected by carotid-femoral pulse wave velocity (CFPWV) and systolic blood pressure with vascular brain injury. The purpose of this study is to examine free water (FW), fractional anisotropy (FA), and white matter hyperintensities (WMH) in relation to arterial stiffness among subjects of the Framingham Offspring and Third-Generation cohorts. In 2422 participants aged 51.3±11.6 years, FA, FW, and WMH were related to CFPWV using voxel-based linear and generalized linear regressions, adjusting for relevant covariables. Mean FW, mean FA, and WMH burden (log transformed) were computed within white matter (WM) region and related to systolic blood pressure and CFPWV using multiple mediation analyses. CFPWV was found to be associated with higher FW, lower FA, and higher WMH incidence in WM areas covering, respectively, 356.1, 211.8, and 10.9 mL of the WM mask. Mediation analyses revealed that the effect of systolic blood pressure on FW was mediated by CFPWV (direct and indirect effects: a=0.040; P<0.001, and a'=0.020; P>0.05). Moreover, the effect of CFPWV on FA was mediated by FW (direct and indirect effects: b=-0.092; P<0.001, and b'=0.012; P>0.05), whose effect on WMH was, in turn, mediated by FA (direct and indirect effects: c=0.246; P<0.001, and c'=0.116; P>0.05). From these data, we propose a biomechanical hypothesis designed for future research experiments to explain how hemodynamic alteration may lead to WM injury by impacting cerebral water content and more subtly WM integrity, to finally lead to WMH development.

Extreme Mountain Ultra-Marathon Leads to Acute but Transient Increase in Cerebral Water Diffusivity and Plasma Biomarkers Levels Changes

Background: Pioneer studies demonstrate the impact of extreme sport load on the human brain, leading to threatening conditions for athlete's health such as cerebral edema. The investigation of brain water diffusivity, allowing the measurement of the intercellular water and the assessment of cerebral edema, can give a great contribution to the investigation of the effects of extreme sports on the brain. We therefore assessed the effect of supra-physiological effort (extreme distance and elevation changes) in mountain ultra-marathons (MUMs) athletes combining for the first time brain magnetic resonance imaging (MRI) and blood parameters.Methods:This longitudinal study included 19 volunteers (44.2 ± 9.5 years) finishing a MUM (330 km, elevation + 24000 m). Quantitative measurements of brain diffusion-weighted images (DWI) were performed at 3 time-points: Before the race, upon arrival and after 48 h. Multiple blood biomarkers were simultaneously investigated. Data analyses included brain apparent diffusion coefficient (ADC) and physiological data comparisons between three time-points.Results:The whole brain ADC significantly increased from baseline to arrival (p = 0.005) and then significantly decreased at recovery (p = 0.005) to lower values than at baseline (p = 0.005). While sodium, potassium, calcium, and chloride as well as hematocrit (HCT) changed over time, the serum osmolality remained constant. Significant correlations were found between whole brain ADC changes and osmolality (p = 0.01), cholesterol (p = 0.009), c-reactive protein (p = 0.04), sodium (p = 0.01), and chloride (p = 0.002) plasma level variations.Conclusions:These results suggest the relative increase of the inter-cellular volume upon arrival, and subsequently its reduction to lower values than at baseline, indicating that even after 48 h the brain has not fully recovered to its equilibrium state. Even though serum electrolytes may only indirectly indicate modifications at the brain level due to the blood brain barrier, the results concerning osmolality suggest that body water might directly influence the change in cerebral ADC. These findings establish therefore a direct link between general brain inter-cellular water content and physiological biomarkers modifications produced by extreme sport.

MiR-124 contributes to M2 polarization of microglia and confers brain inflammatory protection via the C/EBP-α pathway in intracerebral hemorrhage

Microglia mediated inflammation contributes to intracerebral hemorrhage (ICH) induced secondary injury. Activated microglia has dual functions as pro-inflammatory (M1) and anti-inflammatory (M2) factors in brain injury and repair. MiR-124 is a potent anti-inflammatory agent which affects microglia after brain injury. However, the potential of modulating the M1/M2 polarization of microglia after ICH has not been reported. In this experiment, we detected the effect of miR-124 on the M1/M2 polarization state. In addition, the ability miR-124 to subsequently impacted neurological deficit and cerebral water content of ICH mice were studied. Furthermore, the relationship between miR-124 and C/EBP-α target was detected. We found that miR-124 significantly increased in M2-polarized microglia. Transduction of miR-124 mimics decreased proinflammatory cytokine levels. A coculture model of microglia and neuron indicated that M2-polarized microglia protected neuron damage. Furthermore, miR-124 banded to the 3-untranslated region of C/EBP-α and downregulated its protein levels. In vivo, infusion of miR-124 decreased brain levels of C/EBP-α and significantly reduced brain injury in ICH mice. Thus, miR-124 ameliorated ICH-induced inflammatory injury by modulating microglia polarization toward the M2 phenotype via C/EBP-α. MiR-124 regulatory mechanisms also might represent new therapeutic strategy in ICH.

Unfractionated heparin after TBI reduces in vivo cerebrovascular inflammation, brain edema and accelerates cognitive recovery.

Severe traumatic brain injury (TBI) may increase the risk of venous thromboembolic complications; however, early prevention with heparinoids is often withheld for its anticoagulant effect. New evidence suggests low molecular weight heparin reduces cerebral edema and improves neurological recovery after stroke and TBI, through blunting of cerebral leukocyte (LEU) recruitment. It remains unknown if unfractionated heparin (UFH) similarly affects brain inflammation and neurological recovery post-TBI. We hypothesized that UFH after TBI reduces cerebral edema by reducing LEU-mediated inflammation and improves neurological recovery. CD1 male mice underwent either TBI by controlled cortical impact (CCI) or sham craniotomy. UFH (75 U/kg or 225 U/kg) or vehicle (VEH, 0.9% saline) was administered 2, 11, 20, 27, and 34 hours after TBI. At 48 hours, pial intravital microscopy through a craniotomy was used to visualize live brain LEUs interacting with endothelium and microvascular fluorescein isothiocyanate-albumin leakage. Neurologic function (Garcia Neurological Test, GNT) and body weight loss ratios were evaluated 24 and 48 hours after TBI. Cerebral and lung wet-to-dry ratios were evaluated post mortem. ANOVA with Bonferroni correction was used to determine significance (p < 0.05). Compared to positive controls (CCI), both UFH doses reduced post-TBI in vivo LEU rolling on endothelium, concurrent cerebrovascular albumin leakage, and ipsilateral cerebral water content after TBI. Additionally, only low dose UFH (75 U/kg) improved GNT at both 24 and 48 hours after TBI. High dose UFH (225 U/kg) significantly increased body weight loss above sham at 48 hours. Differences in lung water content and blood pressure between groups were not significant. UFH after TBI reduces LEU recruitment, microvascular permeability, and brain edema to injured brain. Lower UFH doses concurrently improve neurological recovery whereas higher UFH may worsen functional recovery. Further study is needed to determine if this is caused by increased bleeding from injured brain with higher UFH doses.